* [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev()
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 8:14 ` Max Reitz
2020-08-19 18:13 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 02/22] qapi: Create block-export module Kevin Wolf
` (20 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/nbd.h | 2 --
nbd/server.c | 5 -----
2 files changed, 7 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 9bc3bfaeec..0451683d03 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -338,8 +338,6 @@ void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
void nbd_export_get(NBDExport *exp);
void nbd_export_put(NBDExport *exp);
-BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
-
AioContext *nbd_export_aio_context(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);
void nbd_export_close_all(void);
diff --git a/nbd/server.c b/nbd/server.c
index 4752a6c8bc..bee2ef8bd1 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1731,11 +1731,6 @@ void nbd_export_put(NBDExport *exp)
}
}
-BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
-{
- return exp->blk;
-}
-
void nbd_export_close_all(void)
{
NBDExport *exp, *next;
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev()
2020-08-13 16:29 ` [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev() Kevin Wolf
@ 2020-08-17 8:14 ` Max Reitz
2020-08-19 18:13 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 8:14 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 242 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 2 --
> nbd/server.c | 5 -----
> 2 files changed, 7 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev()
2020-08-13 16:29 ` [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev() Kevin Wolf
2020-08-17 8:14 ` Max Reitz
@ 2020-08-19 18:13 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 18:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 2 --
> nbd/server.c | 5 -----
> 2 files changed, 7 deletions(-)
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 02/22] qapi: Create block-export module
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
2020-08-13 16:29 ` [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev() Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 8:50 ` Max Reitz
2020-08-19 18:17 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions Kevin Wolf
` (19 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Move all block export related types and commands from block-core to the
new QAPI module block-export.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-core.json | 166 --------------------------
qapi/block-export.json | 172 +++++++++++++++++++++++++++
qapi/qapi-schema.json | 1 +
include/block/nbd.h | 2 +-
block/monitor/block-hmp-cmds.c | 1 +
blockdev-nbd.c | 2 +-
qemu-storage-daemon.c | 2 +-
qapi/Makefile.objs | 5 +-
storage-daemon/qapi/qapi-schema.json | 1 +
9 files changed, 181 insertions(+), 171 deletions(-)
create mode 100644 qapi/block-export.json
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ab7bf3c612..5c491d4cbd 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -5176,172 +5176,6 @@
'iothread': 'StrOrNull',
'*force': 'bool' } }
-##
-# @NbdServerOptions:
-#
-# @addr: Address on which to listen.
-# @tls-creds: ID of the TLS credentials object (since 2.6).
-# @tls-authz: ID of the QAuthZ authorization object used to validate
-# the client's x509 distinguished name. This object is
-# is only resolved at time of use, so can be deleted and
-# recreated on the fly while the NBD server is active.
-# If missing, it will default to denying access (since 4.0).
-#
-# Keep this type consistent with the nbd-server-start arguments. The only
-# intended difference is using SocketAddress instead of SocketAddressLegacy.
-#
-# Since: 4.2
-##
-{ 'struct': 'NbdServerOptions',
- 'data': { 'addr': 'SocketAddress',
- '*tls-creds': 'str',
- '*tls-authz': 'str'} }
-
-##
-# @nbd-server-start:
-#
-# Start an NBD server listening on the given host and port. Block
-# devices can then be exported using @nbd-server-add. The NBD
-# server will present them as named exports; for example, another
-# QEMU instance could refer to them as "nbd:HOST:PORT:exportname=NAME".
-#
-# @addr: Address on which to listen.
-# @tls-creds: ID of the TLS credentials object (since 2.6).
-# @tls-authz: ID of the QAuthZ authorization object used to validate
-# the client's x509 distinguished name. This object is
-# is only resolved at time of use, so can be deleted and
-# recreated on the fly while the NBD server is active.
-# If missing, it will default to denying access (since 4.0).
-#
-# Returns: error if the server is already running.
-#
-# Keep this type consistent with the NbdServerOptions type. The only intended
-# difference is using SocketAddressLegacy instead of SocketAddress.
-#
-# Since: 1.3.0
-##
-{ 'command': 'nbd-server-start',
- 'data': { 'addr': 'SocketAddressLegacy',
- '*tls-creds': 'str',
- '*tls-authz': 'str'} }
-
-##
-# @BlockExportNbd:
-#
-# An NBD block export.
-#
-# @device: The device name or node name of the node to be exported
-#
-# @name: Export name. If unspecified, the @device parameter is used as the
-# export name. (Since 2.12)
-#
-# @description: Free-form description of the export, up to 4096 bytes.
-# (Since 5.0)
-#
-# @writable: Whether clients should be able to write to the device via the
-# NBD connection (default false).
-#
-# @bitmap: Also export the dirty bitmap reachable from @device, so the
-# NBD client can use NBD_OPT_SET_META_CONTEXT with
-# "qemu:dirty-bitmap:NAME" to inspect the bitmap. (since 4.0)
-#
-# Since: 5.0
-##
-{ 'struct': 'BlockExportNbd',
- 'data': {'device': 'str', '*name': 'str', '*description': 'str',
- '*writable': 'bool', '*bitmap': 'str' } }
-
-##
-# @nbd-server-add:
-#
-# Export a block node to QEMU's embedded NBD server.
-#
-# Returns: error if the server is not running, or export with the same name
-# already exists.
-#
-# Since: 1.3.0
-##
-{ 'command': 'nbd-server-add',
- 'data': 'BlockExportNbd', 'boxed': true }
-
-##
-# @NbdServerRemoveMode:
-#
-# Mode for removing an NBD export.
-#
-# @safe: Remove export if there are no existing connections, fail otherwise.
-#
-# @hard: Drop all connections immediately and remove export.
-#
-# Potential additional modes to be added in the future:
-#
-# hide: Just hide export from new clients, leave existing connections as is.
-# Remove export after all clients are disconnected.
-#
-# soft: Hide export from new clients, answer with ESHUTDOWN for all further
-# requests from existing clients.
-#
-# Since: 2.12
-##
-{'enum': 'NbdServerRemoveMode', 'data': ['safe', 'hard']}
-
-##
-# @nbd-server-remove:
-#
-# Remove NBD export by name.
-#
-# @name: Export name.
-#
-# @mode: Mode of command operation. See @NbdServerRemoveMode description.
-# Default is 'safe'.
-#
-# Returns: error if
-# - the server is not running
-# - export is not found
-# - mode is 'safe' and there are existing connections
-#
-# Since: 2.12
-##
-{ 'command': 'nbd-server-remove',
- 'data': {'name': 'str', '*mode': 'NbdServerRemoveMode'} }
-
-##
-# @nbd-server-stop:
-#
-# Stop QEMU's embedded NBD server, and unregister all devices previously
-# added via @nbd-server-add.
-#
-# Since: 1.3.0
-##
-{ 'command': 'nbd-server-stop' }
-
-##
-# @BlockExportType:
-#
-# An enumeration of block export types
-#
-# @nbd: NBD export
-#
-# Since: 4.2
-##
-{ 'enum': 'BlockExportType',
- 'data': [ 'nbd' ] }
-
-##
-# @BlockExport:
-#
-# Describes a block export, i.e. how single node should be exported on an
-# external interface.
-#
-# Since: 4.2
-##
-{ 'union': 'BlockExport',
- 'base': { 'type': 'BlockExportType' },
- 'discriminator': 'type',
- 'data': {
- 'nbd': 'BlockExportNbd'
- } }
-
##
# @QuorumOpType:
#
diff --git a/qapi/block-export.json b/qapi/block-export.json
new file mode 100644
index 0000000000..62f4938e83
--- /dev/null
+++ b/qapi/block-export.json
@@ -0,0 +1,172 @@
+##
+# == Block device exports
+##
+
+{ 'include': 'sockets.json' }
+
+##
+# @NbdServerOptions:
+#
+# @addr: Address on which to listen.
+# @tls-creds: ID of the TLS credentials object (since 2.6).
+# @tls-authz: ID of the QAuthZ authorization object used to validate
+# the client's x509 distinguished name. This object is
+# is only resolved at time of use, so can be deleted and
+# recreated on the fly while the NBD server is active.
+# If missing, it will default to denying access (since 4.0).
+#
+# Keep this type consistent with the nbd-server-start arguments. The only
+# intended difference is using SocketAddress instead of SocketAddressLegacy.
+#
+# Since: 4.2
+##
+{ 'struct': 'NbdServerOptions',
+ 'data': { 'addr': 'SocketAddress',
+ '*tls-creds': 'str',
+ '*tls-authz': 'str'} }
+
+##
+# @nbd-server-start:
+#
+# Start an NBD server listening on the given host and port. Block
+# devices can then be exported using @nbd-server-add. The NBD
+# server will present them as named exports; for example, another
+# QEMU instance could refer to them as "nbd:HOST:PORT:exportname=NAME".
+#
+# @addr: Address on which to listen.
+# @tls-creds: ID of the TLS credentials object (since 2.6).
+# @tls-authz: ID of the QAuthZ authorization object used to validate
+# the client's x509 distinguished name. This object is
+# is only resolved at time of use, so can be deleted and
+# recreated on the fly while the NBD server is active.
+# If missing, it will default to denying access (since 4.0).
+#
+# Returns: error if the server is already running.
+#
+# Keep this type consistent with the NbdServerOptions type. The only intended
+# difference is using SocketAddressLegacy instead of SocketAddress.
+#
+# Since: 1.3.0
+##
+{ 'command': 'nbd-server-start',
+ 'data': { 'addr': 'SocketAddressLegacy',
+ '*tls-creds': 'str',
+ '*tls-authz': 'str'} }
+
+##
+# @BlockExportNbd:
+#
+# An NBD block export.
+#
+# @device: The device name or node name of the node to be exported
+#
+# @name: Export name. If unspecified, the @device parameter is used as the
+# export name. (Since 2.12)
+#
+# @description: Free-form description of the export, up to 4096 bytes.
+# (Since 5.0)
+#
+# @writable: Whether clients should be able to write to the device via the
+# NBD connection (default false).
+#
+# @bitmap: Also export the dirty bitmap reachable from @device, so the
+# NBD client can use NBD_OPT_SET_META_CONTEXT with
+# "qemu:dirty-bitmap:NAME" to inspect the bitmap. (since 4.0)
+#
+# Since: 5.0
+##
+{ 'struct': 'BlockExportNbd',
+ 'data': {'device': 'str', '*name': 'str', '*description': 'str',
+ '*writable': 'bool', '*bitmap': 'str' } }
+
+##
+# @nbd-server-add:
+#
+# Export a block node to QEMU's embedded NBD server.
+#
+# Returns: error if the server is not running, or export with the same name
+# already exists.
+#
+# Since: 1.3.0
+##
+{ 'command': 'nbd-server-add',
+ 'data': 'BlockExportNbd', 'boxed': true }
+
+##
+# @NbdServerRemoveMode:
+#
+# Mode for removing an NBD export.
+#
+# @safe: Remove export if there are no existing connections, fail otherwise.
+#
+# @hard: Drop all connections immediately and remove export.
+#
+# Potential additional modes to be added in the future:
+#
+# hide: Just hide export from new clients, leave existing connections as is.
+# Remove export after all clients are disconnected.
+#
+# soft: Hide export from new clients, answer with ESHUTDOWN for all further
+# requests from existing clients.
+#
+# Since: 2.12
+##
+{'enum': 'NbdServerRemoveMode', 'data': ['safe', 'hard']}
+
+##
+# @nbd-server-remove:
+#
+# Remove NBD export by name.
+#
+# @name: Export name.
+#
+# @mode: Mode of command operation. See @NbdServerRemoveMode description.
+# Default is 'safe'.
+#
+# Returns: error if
+# - the server is not running
+# - export is not found
+# - mode is 'safe' and there are existing connections
+#
+# Since: 2.12
+##
+{ 'command': 'nbd-server-remove',
+ 'data': {'name': 'str', '*mode': 'NbdServerRemoveMode'} }
+
+##
+# @nbd-server-stop:
+#
+# Stop QEMU's embedded NBD server, and unregister all devices previously
+# added via @nbd-server-add.
+#
+# Since: 1.3.0
+##
+{ 'command': 'nbd-server-stop' }
+
+##
+# @BlockExportType:
+#
+# An enumeration of block export types
+#
+# @nbd: NBD export
+#
+# Since: 4.2
+##
+{ 'enum': 'BlockExportType',
+ 'data': [ 'nbd' ] }
+
+##
+# @BlockExport:
+#
+# Describes a block export, i.e. how single node should be exported on an
+# external interface.
+#
+# Since: 4.2
+##
+{ 'union': 'BlockExport',
+ 'base': { 'type': 'BlockExportType' },
+ 'discriminator': 'type',
+ 'data': {
+ 'nbd': 'BlockExportNbd'
+ } }
+
diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
index 43b0ba0dea..2b37f6eb88 100644
--- a/qapi/qapi-schema.json
+++ b/qapi/qapi-schema.json
@@ -63,6 +63,7 @@
{ 'include': 'run-state.json' }
{ 'include': 'crypto.json' }
{ 'include': 'block.json' }
+{ 'include': 'block-export.json' }
{ 'include': 'char.json' }
{ 'include': 'dump.json' }
{ 'include': 'job.json' }
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 0451683d03..262f6da2ce 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -20,7 +20,7 @@
#ifndef NBD_H
#define NBD_H
-#include "qapi/qapi-types-block.h"
+#include "qapi/qapi-types-block-export.h"
#include "io/channel-socket.h"
#include "crypto/tlscreds.h"
#include "qapi/error.h"
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index 4c8c375172..fb9d87ee89 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -40,6 +40,7 @@
#include "sysemu/block-backend.h"
#include "sysemu/blockdev.h"
#include "qapi/qapi-commands-block.h"
+#include "qapi/qapi-commands-block-export.h"
#include "qapi/qmp/qdict.h"
#include "qapi/error.h"
#include "qapi/qmp/qerror.h"
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 1a95d89f00..0f6b80c58f 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -14,7 +14,7 @@
#include "sysemu/block-backend.h"
#include "hw/block/block.h"
#include "qapi/error.h"
-#include "qapi/qapi-commands-block.h"
+#include "qapi/qapi-commands-block-export.h"
#include "block/nbd.h"
#include "io/channel-socket.h"
#include "io/net-listener.h"
diff --git a/qemu-storage-daemon.c b/qemu-storage-daemon.c
index 7e9b0e0d3f..ed9d2afcf3 100644
--- a/qemu-storage-daemon.c
+++ b/qemu-storage-daemon.c
@@ -35,8 +35,8 @@
#include "monitor/monitor-internal.h"
#include "qapi/error.h"
-#include "qapi/qapi-visit-block.h"
#include "qapi/qapi-visit-block-core.h"
+#include "qapi/qapi-visit-block-export.h"
#include "qapi/qapi-visit-control.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.h"
diff --git a/qapi/Makefile.objs b/qapi/Makefile.objs
index 4673ab7490..c5093b4d61 100644
--- a/qapi/Makefile.objs
+++ b/qapi/Makefile.objs
@@ -5,7 +5,8 @@ util-obj-y += opts-visitor.o qapi-clone-visitor.o
util-obj-y += qmp-event.o
util-obj-y += qapi-util.o
-QAPI_COMMON_MODULES = audio authz block-core block char common control crypto
+QAPI_COMMON_MODULES = audio authz block-core block-export block char common
+QAPI_COMMON_MODULES += control crypto
QAPI_COMMON_MODULES += dump error introspect job machine migration misc
QAPI_COMMON_MODULES += net pragma qdev qom rdma rocker run-state sockets tpm
QAPI_COMMON_MODULES += trace transaction ui
@@ -32,7 +33,7 @@ obj-y += $(QAPI_TARGET_MODULES:%=qapi-commands-%.o)
obj-y += qapi-commands.o
obj-y += qapi-init-commands.o
-QAPI_MODULES_STORAGE_DAEMON = block-core char common control crypto
+QAPI_MODULES_STORAGE_DAEMON = block-core block-export char common control crypto
QAPI_MODULES_STORAGE_DAEMON += introspect job qom sockets pragma transaction
storage-daemon-obj-y += $(QAPI_MODULES_STORAGE_DAEMON:%=qapi-commands-%.o)
diff --git a/storage-daemon/qapi/qapi-schema.json b/storage-daemon/qapi/qapi-schema.json
index 14f4f8fe61..9c7133724a 100644
--- a/storage-daemon/qapi/qapi-schema.json
+++ b/storage-daemon/qapi/qapi-schema.json
@@ -15,6 +15,7 @@
{ 'include': '../../qapi/pragma.json' }
{ 'include': '../../qapi/block-core.json' }
+{ 'include': '../../qapi/block-export.json' }
{ 'include': '../../qapi/char.json' }
{ 'include': '../../qapi/common.json' }
{ 'include': '../../qapi/control.json' }
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 02/22] qapi: Create block-export module
2020-08-13 16:29 ` [RFC PATCH 02/22] qapi: Create block-export module Kevin Wolf
@ 2020-08-17 8:50 ` Max Reitz
2020-08-19 18:17 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 8:50 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1183 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Move all block export related types and commands from block-core to the
> new QAPI module block-export.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-core.json | 166 --------------------------
> qapi/block-export.json | 172 +++++++++++++++++++++++++++
> qapi/qapi-schema.json | 1 +
> include/block/nbd.h | 2 +-
> block/monitor/block-hmp-cmds.c | 1 +
> blockdev-nbd.c | 2 +-
> qemu-storage-daemon.c | 2 +-
> qapi/Makefile.objs | 5 +-
> storage-daemon/qapi/qapi-schema.json | 1 +
> 9 files changed, 181 insertions(+), 171 deletions(-)
> create mode 100644 qapi/block-export.json
[...]
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> new file mode 100644
> index 0000000000..62f4938e83
> --- /dev/null
> +++ b/qapi/block-export.json
> @@ -0,0 +1,172 @@
There should probably be a filetype modeline here (not trying to get
into any hornets’ nest here, but... :)).
With that:
Reviewed-by: Max Reitz <mreitz@redhat.com>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 02/22] qapi: Create block-export module
2020-08-13 16:29 ` [RFC PATCH 02/22] qapi: Create block-export module Kevin Wolf
2020-08-17 8:50 ` Max Reitz
@ 2020-08-19 18:17 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 18:17 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Move all block export related types and commands from block-core to the
> new QAPI module block-export.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> +++ b/qapi/block-export.json
> @@ -0,0 +1,172 @@
> +##
> +# == Block device exports
> +##
> +
> +{ 'include': 'sockets.json' }
> +
> +++ b/qapi/Makefile.objs
> @@ -5,7 +5,8 @@ util-obj-y += opts-visitor.o qapi-clone-visitor.o
> util-obj-y += qmp-event.o
> util-obj-y += qapi-util.o
>
> -QAPI_COMMON_MODULES = audio authz block-core block char common control crypto
> +QAPI_COMMON_MODULES = audio authz block-core block-export block char common
> +QAPI_COMMON_MODULES += control crypto
I don't know what Paolo's Meson conversion will affect here, but even if
it changes how this hunk looks, the intent is obvious.
Looks like a straightforward refactoring. I agree with Max's comment on
the missing modeline, but that doesn't stop me from:
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
2020-08-13 16:29 ` [RFC PATCH 01/22] nbd: Remove unused nbd_export_get_blockdev() Kevin Wolf
2020-08-13 16:29 ` [RFC PATCH 02/22] qapi: Create block-export module Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 9:13 ` Max Reitz
2020-08-19 18:19 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add Kevin Wolf
` (18 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
The name BlockExport will be used for the struct containing the runtime
state of block exports, so change the name of export creation options.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 12 ++++++------
block/monitor/block-hmp-cmds.c | 6 +++---
blockdev-nbd.c | 2 +-
qemu-storage-daemon.c | 8 ++++----
4 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 62f4938e83..9332076a05 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -54,7 +54,7 @@
'*tls-authz': 'str'} }
##
-# @BlockExportNbd:
+# @BlockExportOptionsNbd:
#
# An NBD block export.
#
@@ -75,7 +75,7 @@
#
# Since: 5.0
##
-{ 'struct': 'BlockExportNbd',
+{ 'struct': 'BlockExportOptionsNbd',
'data': {'device': 'str', '*name': 'str', '*description': 'str',
'*writable': 'bool', '*bitmap': 'str' } }
@@ -90,7 +90,7 @@
# Since: 1.3.0
##
{ 'command': 'nbd-server-add',
- 'data': 'BlockExportNbd', 'boxed': true }
+ 'data': 'BlockExportOptionsNbd', 'boxed': true }
##
# @NbdServerRemoveMode:
@@ -156,17 +156,17 @@
'data': [ 'nbd' ] }
##
-# @BlockExport:
+# @BlockExportOptions:
#
# Describes a block export, i.e. how single node should be exported on an
# external interface.
#
# Since: 4.2
##
-{ 'union': 'BlockExport',
+{ 'union': 'BlockExportOptions',
'base': { 'type': 'BlockExportType' },
'discriminator': 'type',
'data': {
- 'nbd': 'BlockExportNbd'
+ 'nbd': 'BlockExportOptionsNbd'
} }
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index fb9d87ee89..56bc83ac97 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -398,7 +398,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
Error *local_err = NULL;
BlockInfoList *block_list, *info;
SocketAddress *addr;
- BlockExportNbd export;
+ BlockExportOptionsNbd export;
if (writable && !all) {
error_setg(&local_err, "-w only valid together with -a");
@@ -431,7 +431,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
continue;
}
- export = (BlockExportNbd) {
+ export = (BlockExportOptionsNbd) {
.device = info->value->device,
.has_writable = true,
.writable = writable,
@@ -458,7 +458,7 @@ void hmp_nbd_server_add(Monitor *mon, const QDict *qdict)
bool writable = qdict_get_try_bool(qdict, "writable", false);
Error *local_err = NULL;
- BlockExportNbd export = {
+ BlockExportOptionsNbd export = {
.device = (char *) device,
.has_name = !!name,
.name = (char *) name,
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 0f6b80c58f..98ee1b6170 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -148,7 +148,7 @@ void qmp_nbd_server_start(SocketAddressLegacy *addr,
qapi_free_SocketAddress(addr_flat);
}
-void qmp_nbd_server_add(BlockExportNbd *arg, Error **errp)
+void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
{
BlockDriverState *bs = NULL;
BlockBackend *on_eject_blk;
diff --git a/qemu-storage-daemon.c b/qemu-storage-daemon.c
index ed9d2afcf3..ed26097254 100644
--- a/qemu-storage-daemon.c
+++ b/qemu-storage-daemon.c
@@ -150,7 +150,7 @@ static void init_qmp_commands(void)
qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
}
-static void init_export(BlockExport *export, Error **errp)
+static void init_export(BlockExportOptions *export, Error **errp)
{
switch (export->type) {
case BLOCK_EXPORT_TYPE_NBD:
@@ -235,14 +235,14 @@ static void process_options(int argc, char *argv[])
case OPTION_EXPORT:
{
Visitor *v;
- BlockExport *export;
+ BlockExportOptions *export;
v = qobject_input_visitor_new_str(optarg, "type", &error_fatal);
- visit_type_BlockExport(v, NULL, &export, &error_fatal);
+ visit_type_BlockExportOptions(v, NULL, &export, &error_fatal);
visit_free(v);
init_export(export, &error_fatal);
- qapi_free_BlockExport(export);
+ qapi_free_BlockExportOptions(export);
break;
}
case OPTION_MONITOR:
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions
2020-08-13 16:29 ` [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions Kevin Wolf
@ 2020-08-17 9:13 ` Max Reitz
2020-08-19 18:19 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 9:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 541 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> The name BlockExport will be used for the struct containing the runtime
> state of block exports, so change the name of export creation options.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 12 ++++++------
> block/monitor/block-hmp-cmds.c | 6 +++---
> blockdev-nbd.c | 2 +-
> qemu-storage-daemon.c | 8 ++++----
> 4 files changed, 14 insertions(+), 14 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions
2020-08-13 16:29 ` [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions Kevin Wolf
2020-08-17 9:13 ` Max Reitz
@ 2020-08-19 18:19 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 18:19 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> The name BlockExport will be used for the struct containing the runtime
> state of block exports, so change the name of export creation options.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 12 ++++++------
> block/monitor/block-hmp-cmds.c | 6 +++---
> blockdev-nbd.c | 2 +-
> qemu-storage-daemon.c | 8 ++++----
> 4 files changed, 14 insertions(+), 14 deletions(-)
Mechanical, and doesn't impact introspection.
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (2 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 03/22] qapi: Rename BlockExport to BlockExportOptions Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 10:03 ` Max Reitz
2020-08-19 18:31 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add() Kevin Wolf
` (17 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
We want to have a common set of commands for all types of block exports.
Currently, this is only NBD, but we're going to add more types.
This patch adds the basic BlockExport and BlockExportDriver structs and
a QMP command block-export-add that creates a new export based on the
given BlockExportOptions.
qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 9 ++++++
include/block/export.h | 32 +++++++++++++++++++++
include/block/nbd.h | 3 +-
block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
blockdev-nbd.c | 19 ++++++++-----
nbd/server.c | 15 +++++++++-
Makefile.objs | 6 ++--
block/Makefile.objs | 2 ++
block/export/Makefile.objs | 1 +
9 files changed, 132 insertions(+), 12 deletions(-)
create mode 100644 include/block/export.h
create mode 100644 block/export/export.c
create mode 100644 block/export/Makefile.objs
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 9332076a05..40369814b4 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -170,3 +170,12 @@
'nbd': 'BlockExportOptionsNbd'
} }
+##
+# @block-export-add:
+#
+# Creates a new block export.
+#
+# Since: 5.2
+##
+{ 'command': 'block-export-add',
+ 'data': 'BlockExportOptions', 'boxed': true }
diff --git a/include/block/export.h b/include/block/export.h
new file mode 100644
index 0000000000..b1d7325403
--- /dev/null
+++ b/include/block/export.h
@@ -0,0 +1,32 @@
+/*
+ * Declarations for block exports
+ *
+ * Copyright (c) 2012, 2020 Red Hat, Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ */
+
+#ifndef BLOCK_EXPORT_H
+#define BLOCK_EXPORT_H
+
+#include "qapi/qapi-types-block-export.h"
+
+typedef struct BlockExport BlockExport;
+
+typedef struct BlockExportDriver {
+ BlockExportType type;
+ BlockExport *(*create)(BlockExportOptions *, Error **);
+} BlockExportDriver;
+
+struct BlockExport {
+ const BlockExportDriver *drv;
+};
+
+extern const BlockExportDriver blk_exp_nbd;
+
+#endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 262f6da2ce..c8c5cb6b61 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -20,7 +20,7 @@
#ifndef NBD_H
#define NBD_H
-#include "qapi/qapi-types-block-export.h"
+#include "block/export.h"
#include "io/channel-socket.h"
#include "crypto/tlscreds.h"
#include "qapi/error.h"
@@ -328,6 +328,7 @@ int nbd_errno_to_system_errno(int err);
typedef struct NBDExport NBDExport;
typedef struct NBDClient NBDClient;
+BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp);
NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
uint64_t size, const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
diff --git a/block/export/export.c b/block/export/export.c
new file mode 100644
index 0000000000..3d0dacb3f2
--- /dev/null
+++ b/block/export/export.c
@@ -0,0 +1,57 @@
+/*
+ * Common block export infrastructure
+ *
+ * Copyright (c) 2012, 2020 Red Hat, Inc.
+ *
+ * Authors:
+ * Paolo Bonzini <pbonzini@redhat.com>
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later. See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include "block/export.h"
+#include "block/nbd.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-block-export.h"
+
+static const BlockExportDriver* blk_exp_drivers[] = {
+ &blk_exp_nbd,
+};
+
+static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
+ if (blk_exp_drivers[i]->type == type) {
+ return blk_exp_drivers[i];
+ }
+ }
+ return NULL;
+}
+
+void qmp_block_export_add(BlockExportOptions *export, Error **errp)
+{
+ const BlockExportDriver *drv;
+
+ drv = blk_exp_find_driver(export->type);
+ if (!drv) {
+ error_setg(errp, "No driver found for the requested export type");
+ return;
+ }
+
+ drv->create(export, errp);
+}
+
+void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
+{
+ BlockExportOptions export = {
+ .type = BLOCK_EXPORT_TYPE_NBD,
+ .u.nbd = *arg,
+ };
+ qmp_block_export_add(&export, errp);
+}
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 98ee1b6170..a1dc11bdd7 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -148,17 +148,20 @@ void qmp_nbd_server_start(SocketAddressLegacy *addr,
qapi_free_SocketAddress(addr_flat);
}
-void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
+BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
{
+ BlockExportOptionsNbd *arg = &exp_args->u.nbd;
BlockDriverState *bs = NULL;
BlockBackend *on_eject_blk;
- NBDExport *exp;
+ NBDExport *exp = NULL;
int64_t len;
AioContext *aio_context;
+ assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
+
if (!nbd_server) {
error_setg(errp, "NBD server not running");
- return;
+ return NULL;
}
if (!arg->has_name) {
@@ -167,24 +170,24 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "export name '%s' too long", arg->name);
- return;
+ return NULL;
}
if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "description '%s' too long", arg->description);
- return;
+ return NULL;
}
if (nbd_export_find(arg->name)) {
error_setg(errp, "NBD server already has export named '%s'", arg->name);
- return;
+ return NULL;
}
on_eject_blk = blk_by_name(arg->device);
bs = bdrv_lookup_bs(arg->device, arg->device, errp);
if (!bs) {
- return;
+ return NULL;
}
aio_context = bdrv_get_aio_context(bs);
@@ -217,6 +220,8 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
out:
aio_context_release(aio_context);
+ /* TODO Remove the cast: Move to server.c which can access fields of exp */
+ return (BlockExport*) exp;
}
void qmp_nbd_server_remove(const char *name,
diff --git a/nbd/server.c b/nbd/server.c
index bee2ef8bd1..774325dbe5 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -18,6 +18,8 @@
*/
#include "qemu/osdep.h"
+
+#include "block/export.h"
#include "qapi/error.h"
#include "qemu/queue.h"
#include "trace.h"
@@ -80,6 +82,7 @@ struct NBDRequestData {
};
struct NBDExport {
+ BlockExport common;
int refcount;
void (*close)(NBDExport *exp);
@@ -1512,10 +1515,15 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
{
AioContext *ctx;
BlockBackend *blk;
- NBDExport *exp = g_new0(NBDExport, 1);
+ NBDExport *exp;
uint64_t perm;
int ret;
+ exp = g_new0(NBDExport, 1);
+ exp->common = (BlockExport) {
+ .drv = &blk_exp_nbd,
+ };
+
/*
* NBD exports are used for non-shared storage migration. Make sure
* that BDRV_O_INACTIVE is cleared and the image is ready for write
@@ -1731,6 +1739,11 @@ void nbd_export_put(NBDExport *exp)
}
}
+const BlockExportDriver blk_exp_nbd = {
+ .type = BLOCK_EXPORT_TYPE_NBD,
+ .create = nbd_export_create,
+};
+
void nbd_export_close_all(void)
{
NBDExport *exp, *next;
diff --git a/Makefile.objs b/Makefile.objs
index d22b3b45d7..9b864ca046 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -14,7 +14,7 @@ chardev-obj-y = chardev/
authz-obj-y = authz/
block-obj-y = block/ nbd/ scsi/
-block-obj-y += block.o blockjob.o job.o
+block-obj-y += block.o blockjob.o job.o blockdev-nbd.o
block-obj-y += qemu-io-cmds.o
block-obj-$(CONFIG_REPLICATION) += replication.o
@@ -31,7 +31,7 @@ endif # CONFIG_SOFTMMU or CONFIG_TOOLS
# used for system emulation, too, but specified separately there)
storage-daemon-obj-y = block/ monitor/ qapi/ qom/ storage-daemon/
-storage-daemon-obj-y += blockdev.o blockdev-nbd.o iothread.o job-qmp.o
+storage-daemon-obj-y += blockdev.o iothread.o job-qmp.o
storage-daemon-obj-$(CONFIG_WIN32) += os-win32.o
storage-daemon-obj-$(CONFIG_POSIX) += os-posix.o
@@ -41,7 +41,7 @@ storage-daemon-obj-$(CONFIG_POSIX) += os-posix.o
# single QEMU executable should support all CPUs and machines.
ifeq ($(CONFIG_SOFTMMU),y)
-common-obj-y = blockdev.o blockdev-nbd.o block/
+common-obj-y = blockdev.o block/
common-obj-y += bootdevice.o iothread.o
common-obj-y += dump/
common-obj-y += job-qmp.o
diff --git a/block/Makefile.objs b/block/Makefile.objs
index 19c6f371c9..55b45c2f7d 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -44,6 +44,8 @@ block-obj-y += crypto.o
block-obj-y += aio_task.o
block-obj-y += backup-top.o
block-obj-y += filter-compress.o
+
+block-obj-y += export/
common-obj-y += monitor/
block-obj-y += monitor/
diff --git a/block/export/Makefile.objs b/block/export/Makefile.objs
new file mode 100644
index 0000000000..0c170ee6f1
--- /dev/null
+++ b/block/export/Makefile.objs
@@ -0,0 +1 @@
+block-obj-y += export.o
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-13 16:29 ` [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add Kevin Wolf
@ 2020-08-17 10:03 ` Max Reitz
2020-08-17 12:45 ` Kevin Wolf
2020-08-19 18:31 ` Eric Blake
1 sibling, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 10:03 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 4354 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> We want to have a common set of commands for all types of block exports.
> Currently, this is only NBD, but we're going to add more types.
>
> This patch adds the basic BlockExport and BlockExportDriver structs and
> a QMP command block-export-add that creates a new export based on the
> given BlockExportOptions.
>
> qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 9 ++++++
> include/block/export.h | 32 +++++++++++++++++++++
> include/block/nbd.h | 3 +-
> block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
> blockdev-nbd.c | 19 ++++++++-----
> nbd/server.c | 15 +++++++++-
> Makefile.objs | 6 ++--
> block/Makefile.objs | 2 ++
> block/export/Makefile.objs | 1 +
> 9 files changed, 132 insertions(+), 12 deletions(-)
> create mode 100644 include/block/export.h
> create mode 100644 block/export/export.c
> create mode 100644 block/export/Makefile.objs
Nothing of too great importance below. But it’s an RFC, so comments I
will give.
> diff --git a/block/export/export.c b/block/export/export.c
> new file mode 100644
> index 0000000000..3d0dacb3f2
> --- /dev/null
> +++ b/block/export/export.c
> @@ -0,0 +1,57 @@
> +/*
> + * Common block export infrastructure
> + *
> + * Copyright (c) 2012, 2020 Red Hat, Inc.
> + *
> + * Authors:
> + * Paolo Bonzini <pbonzini@redhat.com>
> + * Kevin Wolf <kwolf@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * later. See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +
> +#include "block/export.h"
> +#include "block/nbd.h"
> +#include "qapi/error.h"
> +#include "qapi/qapi-commands-block-export.h"
> +
> +static const BlockExportDriver* blk_exp_drivers[] = {
^^
Sternenplatzierung *hust*
> + &blk_exp_nbd,
> +};
Not sure whether I like this better than the block driver way of
registering block drivers with a constructor. It requires writing less
code, at the expense of making the variable global. So I think there’s
no good reason to prefer the block driver approach.
Maybe my hesitance comes from the variable being declared (as extern) in
a header file (block/export.h). I think I would prefer it if we put
that external reference only here in this file. Would that work, or do
you have other plans that require blk_exp_nbd to be visible outside of
nbd/server.c and this file here?
> +static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
> + if (blk_exp_drivers[i]->type == type) {
> + return blk_exp_drivers[i];
> + }
> + }
How bad would it be to define blk_exp_drivers as
blk_exp_drivers[BLOCK_EXPORT_TYPE__MAX] and use the BlockExportType as
the driver index so we don’t have to loop here?
Not that it matters performance-wise. Just something I wondered.
> + return NULL;
Why not e.g. g_assert_not_reached()?
(If the BlockExportType were used as the index, I’d assert that
type < ARRAY_SIZE(blk_exp_drivers) && blk_exp_drivers[type] != NULL. I
don’t think there’s a reason for graceful handling.)
> +}
[...]
> +void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> +{
> + BlockExportOptions export = {
> + .type = BLOCK_EXPORT_TYPE_NBD,
> + .u.nbd = *arg,
> + };
> + qmp_block_export_add(&export, errp);
> +}
Hm. I think I’d’ve kept this in blockdev-nbd.c, actually, but, well.
It’ll stay a one-off.
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index 98ee1b6170..a1dc11bdd7 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
[...]
> @@ -217,6 +220,8 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
>
> out:
> aio_context_release(aio_context);
> + /* TODO Remove the cast: Move to server.c which can access fields of exp */
> + return (BlockExport*) exp;
*hust*
(But if it’s moved soon anyway so we can use &exp->common, then whatever.)
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-17 10:03 ` Max Reitz
@ 2020-08-17 12:45 ` Kevin Wolf
2020-08-17 13:19 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 12:45 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
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Am 17.08.2020 um 12:03 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > We want to have a common set of commands for all types of block exports.
> > Currently, this is only NBD, but we're going to add more types.
> >
> > This patch adds the basic BlockExport and BlockExportDriver structs and
> > a QMP command block-export-add that creates a new export based on the
> > given BlockExportOptions.
> >
> > qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 9 ++++++
> > include/block/export.h | 32 +++++++++++++++++++++
> > include/block/nbd.h | 3 +-
> > block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
> > blockdev-nbd.c | 19 ++++++++-----
> > nbd/server.c | 15 +++++++++-
> > Makefile.objs | 6 ++--
> > block/Makefile.objs | 2 ++
> > block/export/Makefile.objs | 1 +
> > 9 files changed, 132 insertions(+), 12 deletions(-)
> > create mode 100644 include/block/export.h
> > create mode 100644 block/export/export.c
> > create mode 100644 block/export/Makefile.objs
>
> Nothing of too great importance below. But it’s an RFC, so comments I
> will give.
>
> > diff --git a/block/export/export.c b/block/export/export.c
> > new file mode 100644
> > index 0000000000..3d0dacb3f2
> > --- /dev/null
> > +++ b/block/export/export.c
> > @@ -0,0 +1,57 @@
> > +/*
> > + * Common block export infrastructure
> > + *
> > + * Copyright (c) 2012, 2020 Red Hat, Inc.
> > + *
> > + * Authors:
> > + * Paolo Bonzini <pbonzini@redhat.com>
> > + * Kevin Wolf <kwolf@redhat.com>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> > + * later. See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +
> > +#include "block/export.h"
> > +#include "block/nbd.h"
> > +#include "qapi/error.h"
> > +#include "qapi/qapi-commands-block-export.h"
> > +
> > +static const BlockExportDriver* blk_exp_drivers[] = {
> ^^
> Sternenplatzierung *hust*
>
> > + &blk_exp_nbd,
> > +};
>
> Not sure whether I like this better than the block driver way of
> registering block drivers with a constructor. It requires writing less
> code, at the expense of making the variable global. So I think there’s
> no good reason to prefer the block driver approach.
I guess I can see one reason why we may want to switch to the
registration style eventually: If we we want to make export drivers
optional modules which may or may not be present.
> Maybe my hesitance comes from the variable being declared (as extern) in
> a header file (block/export.h). I think I would prefer it if we put
> that external reference only here in this file. Would that work, or do
> you have other plans that require blk_exp_nbd to be visible outside of
> nbd/server.c and this file here?
Hm, do we have precedence for "public, but not really" variables?
Normally I expect public symbols to be declared in a header file.
> > +static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
> > + if (blk_exp_drivers[i]->type == type) {
> > + return blk_exp_drivers[i];
> > + }
> > + }
>
> How bad would it be to define blk_exp_drivers as
> blk_exp_drivers[BLOCK_EXPORT_TYPE__MAX] and use the BlockExportType as
> the driver index so we don’t have to loop here?
>
> Not that it matters performance-wise. Just something I wondered.
Might be nicer indeed. It would be incompatible with a registration
model, though, so if we're not sure yet what we want to have in the long
term, maybe the more neutral way is to leave it as it is.
> > + return NULL;
>
> Why not e.g. g_assert_not_reached()?
>
> (If the BlockExportType were used as the index, I’d assert that
> type < ARRAY_SIZE(blk_exp_drivers) && blk_exp_drivers[type] != NULL. I
> don’t think there’s a reason for graceful handling.)
Same thing actually. This works as long as all drivers are always
present.
Now I understand that the current state is somewhat inconsistent in that
it uses a simple array of things that are always present, but has
functions that work as if it were dynamic. I don't mind this
inconsistency very much, but if you do, I guess I could implement a
registration type thing right away.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-17 12:45 ` Kevin Wolf
@ 2020-08-17 13:19 ` Max Reitz
2020-08-17 13:29 ` Kevin Wolf
0 siblings, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 13:19 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
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On 17.08.20 14:45, Kevin Wolf wrote:
> Am 17.08.2020 um 12:03 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> We want to have a common set of commands for all types of block exports.
>>> Currently, this is only NBD, but we're going to add more types.
>>>
>>> This patch adds the basic BlockExport and BlockExportDriver structs and
>>> a QMP command block-export-add that creates a new export based on the
>>> given BlockExportOptions.
>>>
>>> qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> qapi/block-export.json | 9 ++++++
>>> include/block/export.h | 32 +++++++++++++++++++++
>>> include/block/nbd.h | 3 +-
>>> block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
>>> blockdev-nbd.c | 19 ++++++++-----
>>> nbd/server.c | 15 +++++++++-
>>> Makefile.objs | 6 ++--
>>> block/Makefile.objs | 2 ++
>>> block/export/Makefile.objs | 1 +
>>> 9 files changed, 132 insertions(+), 12 deletions(-)
>>> create mode 100644 include/block/export.h
>>> create mode 100644 block/export/export.c
>>> create mode 100644 block/export/Makefile.objs
>>
>> Nothing of too great importance below. But it’s an RFC, so comments I
>> will give.
>>
>>> diff --git a/block/export/export.c b/block/export/export.c
>>> new file mode 100644
>>> index 0000000000..3d0dacb3f2
>>> --- /dev/null
>>> +++ b/block/export/export.c
>>> @@ -0,0 +1,57 @@
>>> +/*
>>> + * Common block export infrastructure
>>> + *
>>> + * Copyright (c) 2012, 2020 Red Hat, Inc.
>>> + *
>>> + * Authors:
>>> + * Paolo Bonzini <pbonzini@redhat.com>
>>> + * Kevin Wolf <kwolf@redhat.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later. See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "qemu/osdep.h"
>>> +
>>> +#include "block/export.h"
>>> +#include "block/nbd.h"
>>> +#include "qapi/error.h"
>>> +#include "qapi/qapi-commands-block-export.h"
>>> +
>>> +static const BlockExportDriver* blk_exp_drivers[] = {
>> ^^
>> Sternenplatzierung *hust*
>>
>>> + &blk_exp_nbd,
>>> +};
>>
>> Not sure whether I like this better than the block driver way of
>> registering block drivers with a constructor. It requires writing less
>> code, at the expense of making the variable global. So I think there’s
>> no good reason to prefer the block driver approach.
>
> I guess I can see one reason why we may want to switch to the
> registration style eventually: If we we want to make export drivers
> optional modules which may or may not be present.
Good point.
>> Maybe my hesitance comes from the variable being declared (as extern) in
>> a header file (block/export.h). I think I would prefer it if we put
>> that external reference only here in this file. Would that work, or do
>> you have other plans that require blk_exp_nbd to be visible outside of
>> nbd/server.c and this file here?
>
> Hm, do we have precedence for "public, but not really" variables?
> Normally I expect public symbols to be declared in a header file.
Hm, yes.
tl;dr: I was wrong about a local external reference being nicer. But I
believe there is a difference between externally-facing header files
(e.g. block.h) and internal header files (e.g. block_int.h). I don’t
know which of those block/export.h is supposed to be.
(And of course it doesn’t even matter at all, really.)
non-tl;dr:
We have a similar case for bdrv_{file,raw,qcow2}, but those are at least
in a *_int.h. I can’t say I like that style.
OK, let me try to figure out what my problem with this is.
I think if a module (in this case the NBD export code) exports
something, it should be available in the respective header (i.e., some
NBD header), not in some other header. A module’s header should present
what it exports to the rest of the code. The export code probably
doesn’t want to export the NBD driver object, it wants to import it,
actually. So if it should be in a header file, it should be in an NBD
header.
Now none of our block drivers has a header file for exporting symbols to
the rest of the block code, which is why their symbols have been put
into block_int.h. I think that’s cutting corners, but can be defended
by saying that block_int.h is not for exporting anything, but just
collects stuff internal to the block layer, so it kind of fits there.
(Still, technically, I believe bdrv_{file,raw,qcow2} should be exported
by each respective block driver in a driver-specific header file. If
that isn’t the case, it doesn’t really matter to me whether it’s put
into a dedicated header file to collect internal stuff (block_int.h) or
just imported locally (with an external declaration) where it’s used.
Probably the dedicated header file is cleaner after all, right.)
Maybe block/export.h is the same in that it’s just supposed to collect
symbols used internally by the export code, then it isn’t wrong to put
it there. But if it’s a header file that may be used by non-export code
to use export functionality, then it would be wrong.
But whatever.
Now I have sorted out my feelings, and they don’t give any result at
all, but it was kind of therapeutic for me.
>>> +static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
>>> +{
>>> + int i;
>>> +
>>> + for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
>>> + if (blk_exp_drivers[i]->type == type) {
>>> + return blk_exp_drivers[i];
>>> + }
>>> + }
>>
>> How bad would it be to define blk_exp_drivers as
>> blk_exp_drivers[BLOCK_EXPORT_TYPE__MAX] and use the BlockExportType as
>> the driver index so we don’t have to loop here?
>>
>> Not that it matters performance-wise. Just something I wondered.
>
> Might be nicer indeed. It would be incompatible with a registration
> model, though, so if we're not sure yet what we want to have in the long
> term, maybe the more neutral way is to leave it as it is.
Yes, true.
>>> + return NULL;
>>
>> Why not e.g. g_assert_not_reached()?
>>
>> (If the BlockExportType were used as the index, I’d assert that
>> type < ARRAY_SIZE(blk_exp_drivers) && blk_exp_drivers[type] != NULL. I
>> don’t think there’s a reason for graceful handling.)
>
> Same thing actually. This works as long as all drivers are always
> present.
>
> Now I understand that the current state is somewhat inconsistent in that
> it uses a simple array of things that are always present, but has
> functions that work as if it were dynamic. I don't mind this
> inconsistency very much, but if you do, I guess I could implement a
> registration type thing right away.
Sounds all reasonable. Thus, I’d leave it like you did it and care
about a registration model if/when we need it.
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-17 13:19 ` Max Reitz
@ 2020-08-17 13:29 ` Kevin Wolf
2020-08-17 13:53 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 13:29 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 6280 bytes --]
Am 17.08.2020 um 15:19 hat Max Reitz geschrieben:
> On 17.08.20 14:45, Kevin Wolf wrote:
> > Am 17.08.2020 um 12:03 hat Max Reitz geschrieben:
> >> On 13.08.20 18:29, Kevin Wolf wrote:
> >>> We want to have a common set of commands for all types of block exports.
> >>> Currently, this is only NBD, but we're going to add more types.
> >>>
> >>> This patch adds the basic BlockExport and BlockExportDriver structs and
> >>> a QMP command block-export-add that creates a new export based on the
> >>> given BlockExportOptions.
> >>>
> >>> qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
> >>>
> >>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> >>> ---
> >>> qapi/block-export.json | 9 ++++++
> >>> include/block/export.h | 32 +++++++++++++++++++++
> >>> include/block/nbd.h | 3 +-
> >>> block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
> >>> blockdev-nbd.c | 19 ++++++++-----
> >>> nbd/server.c | 15 +++++++++-
> >>> Makefile.objs | 6 ++--
> >>> block/Makefile.objs | 2 ++
> >>> block/export/Makefile.objs | 1 +
> >>> 9 files changed, 132 insertions(+), 12 deletions(-)
> >>> create mode 100644 include/block/export.h
> >>> create mode 100644 block/export/export.c
> >>> create mode 100644 block/export/Makefile.objs
> >>
> >> Nothing of too great importance below. But it’s an RFC, so comments I
> >> will give.
> >>
> >>> diff --git a/block/export/export.c b/block/export/export.c
> >>> new file mode 100644
> >>> index 0000000000..3d0dacb3f2
> >>> --- /dev/null
> >>> +++ b/block/export/export.c
> >>> @@ -0,0 +1,57 @@
> >>> +/*
> >>> + * Common block export infrastructure
> >>> + *
> >>> + * Copyright (c) 2012, 2020 Red Hat, Inc.
> >>> + *
> >>> + * Authors:
> >>> + * Paolo Bonzini <pbonzini@redhat.com>
> >>> + * Kevin Wolf <kwolf@redhat.com>
> >>> + *
> >>> + * This work is licensed under the terms of the GNU GPL, version 2 or
> >>> + * later. See the COPYING file in the top-level directory.
> >>> + */
> >>> +
> >>> +#include "qemu/osdep.h"
> >>> +
> >>> +#include "block/export.h"
> >>> +#include "block/nbd.h"
> >>> +#include "qapi/error.h"
> >>> +#include "qapi/qapi-commands-block-export.h"
> >>> +
> >>> +static const BlockExportDriver* blk_exp_drivers[] = {
> >> ^^
> >> Sternenplatzierung *hust*
> >>
> >>> + &blk_exp_nbd,
> >>> +};
> >>
> >> Not sure whether I like this better than the block driver way of
> >> registering block drivers with a constructor. It requires writing less
> >> code, at the expense of making the variable global. So I think there’s
> >> no good reason to prefer the block driver approach.
> >
> > I guess I can see one reason why we may want to switch to the
> > registration style eventually: If we we want to make export drivers
> > optional modules which may or may not be present.
>
> Good point.
>
> >> Maybe my hesitance comes from the variable being declared (as extern) in
> >> a header file (block/export.h). I think I would prefer it if we put
> >> that external reference only here in this file. Would that work, or do
> >> you have other plans that require blk_exp_nbd to be visible outside of
> >> nbd/server.c and this file here?
> >
> > Hm, do we have precedence for "public, but not really" variables?
> > Normally I expect public symbols to be declared in a header file.
>
> Hm, yes.
>
> tl;dr: I was wrong about a local external reference being nicer. But I
> believe there is a difference between externally-facing header files
> (e.g. block.h) and internal header files (e.g. block_int.h). I don’t
> know which of those block/export.h is supposed to be.
>
> (And of course it doesn’t even matter at all, really.)
>
>
> non-tl;dr:
>
> We have a similar case for bdrv_{file,raw,qcow2}, but those are at least
> in a *_int.h. I can’t say I like that style.
>
> OK, let me try to figure out what my problem with this is.
>
> I think if a module (in this case the NBD export code) exports
> something, it should be available in the respective header (i.e., some
> NBD header), not in some other header. A module’s header should present
> what it exports to the rest of the code. The export code probably
> doesn’t want to export the NBD driver object, it wants to import it,
> actually. So if it should be in a header file, it should be in an NBD
> header.
>
> Now none of our block drivers has a header file for exporting symbols to
> the rest of the block code, which is why their symbols have been put
> into block_int.h. I think that’s cutting corners, but can be defended
> by saying that block_int.h is not for exporting anything, but just
> collects stuff internal to the block layer, so it kind of fits there.
>
> (Still, technically, I believe bdrv_{file,raw,qcow2} should be exported
> by each respective block driver in a driver-specific header file. If
> that isn’t the case, it doesn’t really matter to me whether it’s put
> into a dedicated header file to collect internal stuff (block_int.h) or
> just imported locally (with an external declaration) where it’s used.
> Probably the dedicated header file is cleaner after all, right.)
>
> Maybe block/export.h is the same in that it’s just supposed to collect
> symbols used internally by the export code, then it isn’t wrong to put
> it there. But if it’s a header file that may be used by non-export code
> to use export functionality, then it would be wrong.
>
> But whatever.
>
> Now I have sorted out my feelings, and they don’t give any result at
> all, but it was kind of therapeutic for me.
Actually, there could be a conclusion: The declaration shouldn't be in
include/block/export.h, but in include/block/nbd.h. We already include
both headers in block/export/export.c because of qmp_nbd_*().
Of course, you already requests that I leave the other NBD-related stuff
in blockdev-nbd.c rather than moving it there, so the use of blk_exp_nbd
would be the only reason that remains for export.c to include nbd.h.
But it might still be better than having it in export.h.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-17 13:29 ` Kevin Wolf
@ 2020-08-17 13:53 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 13:53 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 6467 bytes --]
On 17.08.20 15:29, Kevin Wolf wrote:
> Am 17.08.2020 um 15:19 hat Max Reitz geschrieben:
>> On 17.08.20 14:45, Kevin Wolf wrote:
>>> Am 17.08.2020 um 12:03 hat Max Reitz geschrieben:
>>>> On 13.08.20 18:29, Kevin Wolf wrote:
>>>>> We want to have a common set of commands for all types of block exports.
>>>>> Currently, this is only NBD, but we're going to add more types.
>>>>>
>>>>> This patch adds the basic BlockExport and BlockExportDriver structs and
>>>>> a QMP command block-export-add that creates a new export based on the
>>>>> given BlockExportOptions.
>>>>>
>>>>> qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
>>>>>
>>>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>>>> ---
>>>>> qapi/block-export.json | 9 ++++++
>>>>> include/block/export.h | 32 +++++++++++++++++++++
>>>>> include/block/nbd.h | 3 +-
>>>>> block/export/export.c | 57 ++++++++++++++++++++++++++++++++++++++
>>>>> blockdev-nbd.c | 19 ++++++++-----
>>>>> nbd/server.c | 15 +++++++++-
>>>>> Makefile.objs | 6 ++--
>>>>> block/Makefile.objs | 2 ++
>>>>> block/export/Makefile.objs | 1 +
>>>>> 9 files changed, 132 insertions(+), 12 deletions(-)
>>>>> create mode 100644 include/block/export.h
>>>>> create mode 100644 block/export/export.c
>>>>> create mode 100644 block/export/Makefile.objs
>>>>
>>>> Nothing of too great importance below. But it’s an RFC, so comments I
>>>> will give.
>>>>
>>>>> diff --git a/block/export/export.c b/block/export/export.c
>>>>> new file mode 100644
>>>>> index 0000000000..3d0dacb3f2
>>>>> --- /dev/null
>>>>> +++ b/block/export/export.c
>>>>> @@ -0,0 +1,57 @@
>>>>> +/*
>>>>> + * Common block export infrastructure
>>>>> + *
>>>>> + * Copyright (c) 2012, 2020 Red Hat, Inc.
>>>>> + *
>>>>> + * Authors:
>>>>> + * Paolo Bonzini <pbonzini@redhat.com>
>>>>> + * Kevin Wolf <kwolf@redhat.com>
>>>>> + *
>>>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>>>> + * later. See the COPYING file in the top-level directory.
>>>>> + */
>>>>> +
>>>>> +#include "qemu/osdep.h"
>>>>> +
>>>>> +#include "block/export.h"
>>>>> +#include "block/nbd.h"
>>>>> +#include "qapi/error.h"
>>>>> +#include "qapi/qapi-commands-block-export.h"
>>>>> +
>>>>> +static const BlockExportDriver* blk_exp_drivers[] = {
>>>> ^^
>>>> Sternenplatzierung *hust*
>>>>
>>>>> + &blk_exp_nbd,
>>>>> +};
>>>>
>>>> Not sure whether I like this better than the block driver way of
>>>> registering block drivers with a constructor. It requires writing less
>>>> code, at the expense of making the variable global. So I think there’s
>>>> no good reason to prefer the block driver approach.
>>>
>>> I guess I can see one reason why we may want to switch to the
>>> registration style eventually: If we we want to make export drivers
>>> optional modules which may or may not be present.
>>
>> Good point.
>>
>>>> Maybe my hesitance comes from the variable being declared (as extern) in
>>>> a header file (block/export.h). I think I would prefer it if we put
>>>> that external reference only here in this file. Would that work, or do
>>>> you have other plans that require blk_exp_nbd to be visible outside of
>>>> nbd/server.c and this file here?
>>>
>>> Hm, do we have precedence for "public, but not really" variables?
>>> Normally I expect public symbols to be declared in a header file.
>>
>> Hm, yes.
>>
>> tl;dr: I was wrong about a local external reference being nicer. But I
>> believe there is a difference between externally-facing header files
>> (e.g. block.h) and internal header files (e.g. block_int.h). I don’t
>> know which of those block/export.h is supposed to be.
>>
>> (And of course it doesn’t even matter at all, really.)
>>
>>
>> non-tl;dr:
>>
>> We have a similar case for bdrv_{file,raw,qcow2}, but those are at least
>> in a *_int.h. I can’t say I like that style.
>>
>> OK, let me try to figure out what my problem with this is.
>>
>> I think if a module (in this case the NBD export code) exports
>> something, it should be available in the respective header (i.e., some
>> NBD header), not in some other header. A module’s header should present
>> what it exports to the rest of the code. The export code probably
>> doesn’t want to export the NBD driver object, it wants to import it,
>> actually. So if it should be in a header file, it should be in an NBD
>> header.
>>
>> Now none of our block drivers has a header file for exporting symbols to
>> the rest of the block code, which is why their symbols have been put
>> into block_int.h. I think that’s cutting corners, but can be defended
>> by saying that block_int.h is not for exporting anything, but just
>> collects stuff internal to the block layer, so it kind of fits there.
>>
>> (Still, technically, I believe bdrv_{file,raw,qcow2} should be exported
>> by each respective block driver in a driver-specific header file. If
>> that isn’t the case, it doesn’t really matter to me whether it’s put
>> into a dedicated header file to collect internal stuff (block_int.h) or
>> just imported locally (with an external declaration) where it’s used.
>> Probably the dedicated header file is cleaner after all, right.)
>>
>> Maybe block/export.h is the same in that it’s just supposed to collect
>> symbols used internally by the export code, then it isn’t wrong to put
>> it there. But if it’s a header file that may be used by non-export code
>> to use export functionality, then it would be wrong.
>>
>> But whatever.
>>
>> Now I have sorted out my feelings, and they don’t give any result at
>> all, but it was kind of therapeutic for me.
>
> Actually, there could be a conclusion: The declaration shouldn't be in
> include/block/export.h, but in include/block/nbd.h. We already include
> both headers in block/export/export.c because of qmp_nbd_*().
Sounds good.
> Of course, you already requests that I leave the other NBD-related stuff
> in blockdev-nbd.c rather than moving it there, so the use of blk_exp_nbd
> would be the only reason that remains for export.c to include nbd.h.
Aww. That’s too bad.
> But it might still be better than having it in export.h.
I’ll take the easy way out and leave it to you.
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add
2020-08-13 16:29 ` [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add Kevin Wolf
2020-08-17 10:03 ` Max Reitz
@ 2020-08-19 18:31 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 18:31 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> We want to have a common set of commands for all types of block exports.
> Currently, this is only NBD, but we're going to add more types.
>
> This patch adds the basic BlockExport and BlockExportDriver structs and
> a QMP command block-export-add that creates a new export based on the
> given BlockExportOptions.
>
> qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
Seeing if I can spot anything beyond Max's fine points:
> +++ b/qapi/block-export.json
> @@ -170,3 +170,12 @@
> 'nbd': 'BlockExportOptionsNbd'
> } }
>
> +##
> +# @block-export-add:
> +#
> +# Creates a new block export.
> +#
> +# Since: 5.2
> +##
> +{ 'command': 'block-export-add',
> + 'data': 'BlockExportOptions', 'boxed': true }
So if I read patch 3 correctly, the difference between nbd-server-add
and block-export-add is that the latter includes a "type":"nbd" member.
(If we ever play with allowing a default discriminator value in QAPI, we
could declare the default for "type" to be NBD, and then the two would
be identical - except that since you are adding a new command designed
to extend to more than just nbd, I don't think keeping nbd as default
makes sense)
> +++ b/block/export/export.c
> +void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> +{
> + BlockExportOptions export = {
> + .type = BLOCK_EXPORT_TYPE_NBD,
> + .u.nbd = *arg,
> + };
> + qmp_block_export_add(&export, errp);
> +}
And indeed, this matches that analysis.
> @@ -217,6 +220,8 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
>
> out:
> aio_context_release(aio_context);
> + /* TODO Remove the cast: Move to server.c which can access fields of exp */
> + return (BlockExport*) exp;
Should this use container_of()? Ah, the TODO says you want to, but
can't because exp is an opaque type in this file...
> }
>
> void qmp_nbd_server_remove(const char *name,
> diff --git a/nbd/server.c b/nbd/server.c
> index bee2ef8bd1..774325dbe5 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -18,6 +18,8 @@
> */
>
> #include "qemu/osdep.h"
> +
> +#include "block/export.h"
> #include "qapi/error.h"
> #include "qemu/queue.h"
> #include "trace.h"
> @@ -80,6 +82,7 @@ struct NBDRequestData {
> };
>
> struct NBDExport {
> + BlockExport common;
...but at least the cast is accurate.
Overall, the idea looks sane. I'm happy if you want to move
blockdev-nbd.c out of the top level.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add()
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (3 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 04/22] block/export: Add BlockExport infrastructure and block-export-add Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 10:13 ` Max Reitz
2020-08-19 19:14 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
` (16 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
No reason to duplicate the functionality locally, we can now just reuse
the QMP command block-export-add for --export.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qemu-storage-daemon.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
diff --git a/qemu-storage-daemon.c b/qemu-storage-daemon.c
index ed26097254..b6f678d3ab 100644
--- a/qemu-storage-daemon.c
+++ b/qemu-storage-daemon.c
@@ -150,17 +150,6 @@ static void init_qmp_commands(void)
qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
}
-static void init_export(BlockExportOptions *export, Error **errp)
-{
- switch (export->type) {
- case BLOCK_EXPORT_TYPE_NBD:
- qmp_nbd_server_add(&export->u.nbd, errp);
- break;
- default:
- g_assert_not_reached();
- }
-}
-
static void process_options(int argc, char *argv[])
{
int c;
@@ -241,7 +230,7 @@ static void process_options(int argc, char *argv[])
visit_type_BlockExportOptions(v, NULL, &export, &error_fatal);
visit_free(v);
- init_export(export, &error_fatal);
+ qmp_block_export_add(export, &error_fatal);
qapi_free_BlockExportOptions(export);
break;
}
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add()
2020-08-13 16:29 ` [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add() Kevin Wolf
@ 2020-08-17 10:13 ` Max Reitz
2020-08-19 19:14 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 10:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 367 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> No reason to duplicate the functionality locally, we can now just reuse
> the QMP command block-export-add for --export.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qemu-storage-daemon.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add()
2020-08-13 16:29 ` [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add() Kevin Wolf
2020-08-17 10:13 ` Max Reitz
@ 2020-08-19 19:14 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 19:14 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> No reason to duplicate the functionality locally, we can now just reuse
> the QMP command block-export-add for --export.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qemu-storage-daemon.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
>
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (4 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 05/22] qemu-storage-daemon: Use qmp_block_export_add() Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 10:56 ` Max Reitz
` (3 more replies)
2020-08-13 16:29 ` [RFC PATCH 07/22] block/export: Remove magic from block-export-add Kevin Wolf
` (15 subsequent siblings)
21 siblings, 4 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Instead of implementing qemu-nbd --offset in the NBD code, just put a
raw block node with the requested offset on top of the user image and
rely on that doing the job.
This does not only simplify the nbd_export_new() interface and bring it
closer to the set of options that the nbd-server-add QMP command offers,
but in fact it also eliminates a potential source for bugs in the NBD
code which previously had to add the offset manually in all relevant
places.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/nbd.h | 4 ++--
blockdev-nbd.c | 9 +--------
nbd/server.c | 34 +++++++++++++++++-----------------
qemu-nbd.c | 27 ++++++++++++---------------
4 files changed, 32 insertions(+), 42 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index c8c5cb6b61..3846d2bac8 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -329,8 +329,8 @@ typedef struct NBDExport NBDExport;
typedef struct NBDClient NBDClient;
BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp);
-NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
- uint64_t size, const char *name, const char *desc,
+NBDExport *nbd_export_new(BlockDriverState *bs,
+ const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
void (*close)(NBDExport *), bool writethrough,
BlockBackend *on_eject_blk, Error **errp);
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index a1dc11bdd7..16cda3b052 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -154,7 +154,6 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
BlockDriverState *bs = NULL;
BlockBackend *on_eject_blk;
NBDExport *exp = NULL;
- int64_t len;
AioContext *aio_context;
assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
@@ -192,12 +191,6 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
- len = bdrv_getlength(bs);
- if (len < 0) {
- error_setg_errno(errp, -len,
- "Failed to determine the NBD export's length");
- goto out;
- }
if (!arg->has_writable) {
arg->writable = false;
@@ -206,7 +199,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
arg->writable = false;
}
- exp = nbd_export_new(bs, 0, len, arg->name, arg->description, arg->bitmap,
+ exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
!arg->writable, !arg->writable,
NULL, false, on_eject_blk, errp);
if (!exp) {
diff --git a/nbd/server.c b/nbd/server.c
index 774325dbe5..92360d1f08 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -89,7 +89,6 @@ struct NBDExport {
BlockBackend *blk;
char *name;
char *description;
- uint64_t dev_offset;
uint64_t size;
uint16_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
@@ -1507,8 +1506,8 @@ static void nbd_eject_notifier(Notifier *n, void *data)
aio_context_release(aio_context);
}
-NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
- uint64_t size, const char *name, const char *desc,
+NBDExport *nbd_export_new(BlockDriverState *bs,
+ const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
void (*close)(NBDExport *), bool writethrough,
BlockBackend *on_eject_blk, Error **errp)
@@ -1516,9 +1515,17 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
AioContext *ctx;
BlockBackend *blk;
NBDExport *exp;
+ int64_t size;
uint64_t perm;
int ret;
+ size = bdrv_getlength(bs);
+ if (size < 0) {
+ error_setg_errno(errp, -size,
+ "Failed to determine the NBD export's length");
+ return NULL;
+ }
+
exp = g_new0(NBDExport, 1);
exp->common = (BlockExport) {
.drv = &blk_exp_nbd,
@@ -1553,8 +1560,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
- assert(dev_offset <= INT64_MAX);
- exp->dev_offset = dev_offset;
exp->name = g_strdup(name);
assert(!desc || strlen(desc) <= NBD_MAX_STRING_SIZE);
exp->description = g_strdup(desc);
@@ -1569,7 +1574,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
NBD_FLAG_SEND_FAST_ZERO);
}
- assert(size <= INT64_MAX - dev_offset);
+ assert(size <= INT64_MAX);
exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
if (bitmap) {
@@ -1928,8 +1933,7 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client,
stl_be_p(&chunk.length, pnum);
ret = nbd_co_send_iov(client, iov, 1, errp);
} else {
- ret = blk_pread(exp->blk, offset + progress + exp->dev_offset,
- data + progress, pnum);
+ ret = blk_pread(exp->blk, offset + progress, data + progress, pnum);
if (ret < 0) {
error_setg_errno(errp, -ret, "reading from file failed");
break;
@@ -2303,8 +2307,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request,
data, request->len, errp);
}
- ret = blk_pread(exp->blk, request->from + exp->dev_offset, data,
- request->len);
+ ret = blk_pread(exp->blk, request->from, data, request->len);
if (ret < 0) {
return nbd_send_generic_reply(client, request->handle, ret,
"reading from file failed", errp);
@@ -2339,7 +2342,7 @@ static coroutine_fn int nbd_do_cmd_cache(NBDClient *client, NBDRequest *request,
assert(request->type == NBD_CMD_CACHE);
- ret = blk_co_preadv(exp->blk, request->from + exp->dev_offset, request->len,
+ ret = blk_co_preadv(exp->blk, request->from, request->len,
NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
return nbd_send_generic_reply(client, request->handle, ret,
@@ -2370,8 +2373,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
if (request->flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
- ret = blk_pwrite(exp->blk, request->from + exp->dev_offset,
- data, request->len, flags);
+ ret = blk_pwrite(exp->blk, request->from, data, request->len, flags);
return nbd_send_generic_reply(client, request->handle, ret,
"writing to file failed", errp);
@@ -2386,8 +2388,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
flags |= BDRV_REQ_NO_FALLBACK;
}
- ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
- request->len, flags);
+ ret = blk_pwrite_zeroes(exp->blk, request->from, request->len, flags);
return nbd_send_generic_reply(client, request->handle, ret,
"writing to file failed", errp);
@@ -2401,8 +2402,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
"flush failed", errp);
case NBD_CMD_TRIM:
- ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset,
- request->len);
+ ret = blk_co_pdiscard(exp->blk, request->from, request->len);
if (ret == 0 && request->flags & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->blk);
}
diff --git a/qemu-nbd.c b/qemu-nbd.c
index d2657b8db5..818c3f5d46 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -523,7 +523,6 @@ int main(int argc, char **argv)
const char *port = NULL;
char *sockpath = NULL;
char *device = NULL;
- int64_t fd_size;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
@@ -1028,6 +1027,17 @@ int main(int argc, char **argv)
}
bs = blk_bs(blk);
+ if (dev_offset) {
+ QDict *raw_opts = qdict_new();
+ qdict_put_str(raw_opts, "driver", "raw");
+ qdict_put_str(raw_opts, "file", bs->node_name);
+ qdict_put_int(raw_opts, "offset", dev_offset);
+ bs = bdrv_open(NULL, NULL, raw_opts, flags, &error_fatal);
+ blk_remove_bs(blk);
+ blk_insert_bs(blk, bs, &error_fatal);
+ bdrv_unref(bs);
+ }
+
blk_set_enable_write_cache(blk, !writethrough);
if (sn_opts) {
@@ -1045,21 +1055,8 @@ int main(int argc, char **argv)
}
bs->detect_zeroes = detect_zeroes;
- fd_size = blk_getlength(blk);
- if (fd_size < 0) {
- error_report("Failed to determine the image length: %s",
- strerror(-fd_size));
- exit(EXIT_FAILURE);
- }
-
- if (dev_offset >= fd_size) {
- error_report("Offset (%" PRIu64 ") has to be smaller than the image "
- "size (%" PRId64 ")", dev_offset, fd_size);
- exit(EXIT_FAILURE);
- }
- fd_size -= dev_offset;
- export = nbd_export_new(bs, dev_offset, fd_size, export_name,
+ export = nbd_export_new(bs, export_name,
export_description, bitmap, readonly, shared > 1,
nbd_export_closed, writethrough, NULL,
&error_fatal);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
@ 2020-08-17 10:56 ` Max Reitz
2020-08-17 11:41 ` Max Reitz
` (2 subsequent siblings)
3 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 10:56 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 882 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Instead of implementing qemu-nbd --offset in the NBD code, just put a
> raw block node with the requested offset on top of the user image and
> rely on that doing the job.
>
> This does not only simplify the nbd_export_new() interface and bring it
> closer to the set of options that the nbd-server-add QMP command offers,
> but in fact it also eliminates a potential source for bugs in the NBD
> code which previously had to add the offset manually in all relevant
> places.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 4 ++--
> blockdev-nbd.c | 9 +--------
> nbd/server.c | 34 +++++++++++++++++-----------------
> qemu-nbd.c | 27 ++++++++++++---------------
> 4 files changed, 32 insertions(+), 42 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
2020-08-17 10:56 ` Max Reitz
@ 2020-08-17 11:41 ` Max Reitz
2020-08-17 17:19 ` Nir Soffer
2020-08-19 19:33 ` Eric Blake
3 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 11:41 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1385 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Instead of implementing qemu-nbd --offset in the NBD code, just put a
> raw block node with the requested offset on top of the user image and
> rely on that doing the job.
>
> This does not only simplify the nbd_export_new() interface and bring it
> closer to the set of options that the nbd-server-add QMP command offers,
> but in fact it also eliminates a potential source for bugs in the NBD
> code which previously had to add the offset manually in all relevant
> places.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 4 ++--
> blockdev-nbd.c | 9 +--------
> nbd/server.c | 34 +++++++++++++++++-----------------
> qemu-nbd.c | 27 ++++++++++++---------------
> 4 files changed, 32 insertions(+), 42 deletions(-)
[...]
> diff --git a/nbd/server.c b/nbd/server.c
> index 774325dbe5..92360d1f08 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
[...]
> @@ -1569,7 +1574,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
> exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
> NBD_FLAG_SEND_FAST_ZERO);
> }
> - assert(size <= INT64_MAX - dev_offset);
> + assert(size <= INT64_MAX);
Forgot to note: I think we can drop this assertion altogether now.
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
2020-08-17 10:56 ` Max Reitz
2020-08-17 11:41 ` Max Reitz
@ 2020-08-17 17:19 ` Nir Soffer
2020-08-18 8:47 ` Kevin Wolf
2020-08-19 19:33 ` Eric Blake
3 siblings, 1 reply; 90+ messages in thread
From: Nir Soffer @ 2020-08-17 17:19 UTC (permalink / raw)
To: Kevin Wolf; +Cc: QEMU Developers, qemu-block, Max Reitz
[-- Attachment #1: Type: text/plain, Size: 11128 bytes --]
On Thu, Aug 13, 2020 at 7:36 PM Kevin Wolf <kwolf@redhat.com> wrote:
> Instead of implementing qemu-nbd --offset in the NBD code, just put a
> raw block node with the requested offset on top of the user image and
> rely on that doing the job.
>
> This does not only simplify the nbd_export_new() interface and bring it
> closer to the set of options that the nbd-server-add QMP command offers,
> but in fact it also eliminates a potential source for bugs in the NBD
> code which previously had to add the offset manually in all relevant
> places.
>
Just to make sure I understand this correctly -
qemu-nbd can work with:
$ qemu-nbd 'json:{"driver": "file", "filename": "test.raw"}'
And:
$ qemu-nbd 'json:{"driver": "raw", "file": {"driver": "file",
"filename": "test.raw"}}'
I assumed that we always create the raw node?
oVirt always uses the second form to make it easier to support offset,
size, and backing.
https://github.com/oVirt/ovirt-imageio/blob/2021164d064227d7c5e03c8da087adc66e3a577e/daemon/ovirt_imageio/_internal/qemu_nbd.py#L104
This also seems to be the way libvirt builds the nodes using -blockdev.
Do we have a way to visualize the internal node graph used by
qemu-nbd/qemu-img?
Nir
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 4 ++--
> blockdev-nbd.c | 9 +--------
> nbd/server.c | 34 +++++++++++++++++-----------------
> qemu-nbd.c | 27 ++++++++++++---------------
> 4 files changed, 32 insertions(+), 42 deletions(-)
>
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index c8c5cb6b61..3846d2bac8 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -329,8 +329,8 @@ typedef struct NBDExport NBDExport;
> typedef struct NBDClient NBDClient;
>
> BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error
> **errp);
> -NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
> - uint64_t size, const char *name, const char
> *desc,
> +NBDExport *nbd_export_new(BlockDriverState *bs,
> + const char *name, const char *desc,
> const char *bitmap, bool readonly, bool shared,
> void (*close)(NBDExport *), bool writethrough,
> BlockBackend *on_eject_blk, Error **errp);
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index a1dc11bdd7..16cda3b052 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
> @@ -154,7 +154,6 @@ BlockExport *nbd_export_create(BlockExportOptions
> *exp_args, Error **errp)
> BlockDriverState *bs = NULL;
> BlockBackend *on_eject_blk;
> NBDExport *exp = NULL;
> - int64_t len;
> AioContext *aio_context;
>
> assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
> @@ -192,12 +191,6 @@ BlockExport *nbd_export_create(BlockExportOptions
> *exp_args, Error **errp)
>
> aio_context = bdrv_get_aio_context(bs);
> aio_context_acquire(aio_context);
> - len = bdrv_getlength(bs);
> - if (len < 0) {
> - error_setg_errno(errp, -len,
> - "Failed to determine the NBD export's length");
> - goto out;
> - }
>
> if (!arg->has_writable) {
> arg->writable = false;
> @@ -206,7 +199,7 @@ BlockExport *nbd_export_create(BlockExportOptions
> *exp_args, Error **errp)
> arg->writable = false;
> }
>
> - exp = nbd_export_new(bs, 0, len, arg->name, arg->description,
> arg->bitmap,
> + exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
> !arg->writable, !arg->writable,
> NULL, false, on_eject_blk, errp);
> if (!exp) {
> diff --git a/nbd/server.c b/nbd/server.c
> index 774325dbe5..92360d1f08 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -89,7 +89,6 @@ struct NBDExport {
> BlockBackend *blk;
> char *name;
> char *description;
> - uint64_t dev_offset;
> uint64_t size;
> uint16_t nbdflags;
> QTAILQ_HEAD(, NBDClient) clients;
> @@ -1507,8 +1506,8 @@ static void nbd_eject_notifier(Notifier *n, void
> *data)
> aio_context_release(aio_context);
> }
>
> -NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
> - uint64_t size, const char *name, const char
> *desc,
> +NBDExport *nbd_export_new(BlockDriverState *bs,
> + const char *name, const char *desc,
> const char *bitmap, bool readonly, bool shared,
> void (*close)(NBDExport *), bool writethrough,
> BlockBackend *on_eject_blk, Error **errp)
> @@ -1516,9 +1515,17 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> uint64_t dev_offset,
> AioContext *ctx;
> BlockBackend *blk;
> NBDExport *exp;
> + int64_t size;
> uint64_t perm;
> int ret;
>
> + size = bdrv_getlength(bs);
> + if (size < 0) {
> + error_setg_errno(errp, -size,
> + "Failed to determine the NBD export's length");
> + return NULL;
> + }
> +
> exp = g_new0(NBDExport, 1);
> exp->common = (BlockExport) {
> .drv = &blk_exp_nbd,
> @@ -1553,8 +1560,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> uint64_t dev_offset,
> exp->refcount = 1;
> QTAILQ_INIT(&exp->clients);
> exp->blk = blk;
> - assert(dev_offset <= INT64_MAX);
> - exp->dev_offset = dev_offset;
> exp->name = g_strdup(name);
> assert(!desc || strlen(desc) <= NBD_MAX_STRING_SIZE);
> exp->description = g_strdup(desc);
> @@ -1569,7 +1574,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> uint64_t dev_offset,
> exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES
> |
> NBD_FLAG_SEND_FAST_ZERO);
> }
> - assert(size <= INT64_MAX - dev_offset);
> + assert(size <= INT64_MAX);
> exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
>
> if (bitmap) {
> @@ -1928,8 +1933,7 @@ static int coroutine_fn
> nbd_co_send_sparse_read(NBDClient *client,
> stl_be_p(&chunk.length, pnum);
> ret = nbd_co_send_iov(client, iov, 1, errp);
> } else {
> - ret = blk_pread(exp->blk, offset + progress + exp->dev_offset,
> - data + progress, pnum);
> + ret = blk_pread(exp->blk, offset + progress, data + progress,
> pnum);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "reading from file failed");
> break;
> @@ -2303,8 +2307,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient
> *client, NBDRequest *request,
> data, request->len, errp);
> }
>
> - ret = blk_pread(exp->blk, request->from + exp->dev_offset, data,
> - request->len);
> + ret = blk_pread(exp->blk, request->from, data, request->len);
> if (ret < 0) {
> return nbd_send_generic_reply(client, request->handle, ret,
> "reading from file failed", errp);
> @@ -2339,7 +2342,7 @@ static coroutine_fn int nbd_do_cmd_cache(NBDClient
> *client, NBDRequest *request,
>
> assert(request->type == NBD_CMD_CACHE);
>
> - ret = blk_co_preadv(exp->blk, request->from + exp->dev_offset,
> request->len,
> + ret = blk_co_preadv(exp->blk, request->from, request->len,
> NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
>
> return nbd_send_generic_reply(client, request->handle, ret,
> @@ -2370,8 +2373,7 @@ static coroutine_fn int nbd_handle_request(NBDClient
> *client,
> if (request->flags & NBD_CMD_FLAG_FUA) {
> flags |= BDRV_REQ_FUA;
> }
> - ret = blk_pwrite(exp->blk, request->from + exp->dev_offset,
> - data, request->len, flags);
> + ret = blk_pwrite(exp->blk, request->from, data, request->len,
> flags);
> return nbd_send_generic_reply(client, request->handle, ret,
> "writing to file failed", errp);
>
> @@ -2386,8 +2388,7 @@ static coroutine_fn int nbd_handle_request(NBDClient
> *client,
> if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
> flags |= BDRV_REQ_NO_FALLBACK;
> }
> - ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
> - request->len, flags);
> + ret = blk_pwrite_zeroes(exp->blk, request->from, request->len,
> flags);
> return nbd_send_generic_reply(client, request->handle, ret,
> "writing to file failed", errp);
>
> @@ -2401,8 +2402,7 @@ static coroutine_fn int nbd_handle_request(NBDClient
> *client,
> "flush failed", errp);
>
> case NBD_CMD_TRIM:
> - ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset,
> - request->len);
> + ret = blk_co_pdiscard(exp->blk, request->from, request->len);
> if (ret == 0 && request->flags & NBD_CMD_FLAG_FUA) {
> ret = blk_co_flush(exp->blk);
> }
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index d2657b8db5..818c3f5d46 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -523,7 +523,6 @@ int main(int argc, char **argv)
> const char *port = NULL;
> char *sockpath = NULL;
> char *device = NULL;
> - int64_t fd_size;
> QemuOpts *sn_opts = NULL;
> const char *sn_id_or_name = NULL;
> const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
> @@ -1028,6 +1027,17 @@ int main(int argc, char **argv)
> }
> bs = blk_bs(blk);
>
> + if (dev_offset) {
> + QDict *raw_opts = qdict_new();
> + qdict_put_str(raw_opts, "driver", "raw");
> + qdict_put_str(raw_opts, "file", bs->node_name);
> + qdict_put_int(raw_opts, "offset", dev_offset);
> + bs = bdrv_open(NULL, NULL, raw_opts, flags, &error_fatal);
> + blk_remove_bs(blk);
> + blk_insert_bs(blk, bs, &error_fatal);
> + bdrv_unref(bs);
> + }
> +
> blk_set_enable_write_cache(blk, !writethrough);
>
> if (sn_opts) {
> @@ -1045,21 +1055,8 @@ int main(int argc, char **argv)
> }
>
> bs->detect_zeroes = detect_zeroes;
> - fd_size = blk_getlength(blk);
> - if (fd_size < 0) {
> - error_report("Failed to determine the image length: %s",
> - strerror(-fd_size));
> - exit(EXIT_FAILURE);
> - }
> -
> - if (dev_offset >= fd_size) {
> - error_report("Offset (%" PRIu64 ") has to be smaller than the
> image "
> - "size (%" PRId64 ")", dev_offset, fd_size);
> - exit(EXIT_FAILURE);
> - }
> - fd_size -= dev_offset;
>
> - export = nbd_export_new(bs, dev_offset, fd_size, export_name,
> + export = nbd_export_new(bs, export_name,
> export_description, bitmap, readonly, shared
> > 1,
> nbd_export_closed, writethrough, NULL,
> &error_fatal);
> --
> 2.25.4
>
>
>
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-17 17:19 ` Nir Soffer
@ 2020-08-18 8:47 ` Kevin Wolf
2020-08-18 9:05 ` Nir Soffer
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-18 8:47 UTC (permalink / raw)
To: Nir Soffer; +Cc: QEMU Developers, qemu-block, Max Reitz
Am 17.08.2020 um 19:19 hat Nir Soffer geschrieben:
> On Thu, Aug 13, 2020 at 7:36 PM Kevin Wolf <kwolf@redhat.com> wrote:
>
> > Instead of implementing qemu-nbd --offset in the NBD code, just put a
> > raw block node with the requested offset on top of the user image and
> > rely on that doing the job.
> >
> > This does not only simplify the nbd_export_new() interface and bring it
> > closer to the set of options that the nbd-server-add QMP command offers,
> > but in fact it also eliminates a potential source for bugs in the NBD
> > code which previously had to add the offset manually in all relevant
> > places.
> >
>
> Just to make sure I understand this correctly -
>
> qemu-nbd can work with:
>
> $ qemu-nbd 'json:{"driver": "file", "filename": "test.raw"}'
>
> And:
>
> $ qemu-nbd 'json:{"driver": "raw", "file": {"driver": "file",
> "filename": "test.raw"}}'
>
> I assumed that we always create the raw node?
No, the first form creates only the 'file' node without a 'raw' node on
top. For all practical matters, this should be the same in qemu-img or
qemu-nbd. For actually running VMs, omitting the 'raw' node where it's
not needed can improve performance a little.
What is true is that if you use a filename without specifying the driver
(i.e. you rely on format probing), you'll get a 'raw' node on top of
the 'file' node.
> oVirt always uses the second form to make it easier to support offset,
> size, and backing.
> https://github.com/oVirt/ovirt-imageio/blob/2021164d064227d7c5e03c8da087adc66e3a577e/daemon/ovirt_imageio/_internal/qemu_nbd.py#L104
>
> This also seems to be the way libvirt builds the nodes using -blockdev.
libvirt actually has a BZ to avoid the 'raw' node for performance when
it's not needed.
> Do we have a way to visualize the internal node graph used by
> qemu-nbd/qemu-img?
No, but as long as you explicitly specify the driver, you get exactly
what you specified.
For exploring what happens, you can pass the same json: filename to QEMU
(maybe with -hda) and then use the monitor to inspect the state.
Kevin
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-18 8:47 ` Kevin Wolf
@ 2020-08-18 9:05 ` Nir Soffer
0 siblings, 0 replies; 90+ messages in thread
From: Nir Soffer @ 2020-08-18 9:05 UTC (permalink / raw)
To: Kevin Wolf; +Cc: QEMU Developers, qemu-block, Max Reitz
[-- Attachment #1: Type: text/plain, Size: 2476 bytes --]
On Tue, Aug 18, 2020 at 11:47 AM Kevin Wolf <kwolf@redhat.com> wrote:
> Am 17.08.2020 um 19:19 hat Nir Soffer geschrieben:
> > On Thu, Aug 13, 2020 at 7:36 PM Kevin Wolf <kwolf@redhat.com> wrote:
> >
> > > Instead of implementing qemu-nbd --offset in the NBD code, just put a
> > > raw block node with the requested offset on top of the user image and
> > > rely on that doing the job.
> > >
> > > This does not only simplify the nbd_export_new() interface and bring it
> > > closer to the set of options that the nbd-server-add QMP command
> offers,
> > > but in fact it also eliminates a potential source for bugs in the NBD
> > > code which previously had to add the offset manually in all relevant
> > > places.
> > >
> >
> > Just to make sure I understand this correctly -
> >
> > qemu-nbd can work with:
> >
> > $ qemu-nbd 'json:{"driver": "file", "filename": "test.raw"}'
> >
> > And:
> >
> > $ qemu-nbd 'json:{"driver": "raw", "file": {"driver": "file",
> > "filename": "test.raw"}}'
> >
> > I assumed that we always create the raw node?
>
> No, the first form creates only the 'file' node without a 'raw' node on
> top. For all practical matters, this should be the same in qemu-img or
> qemu-nbd. For actually running VMs, omitting the 'raw' node where it's
> not needed can improve performance a little.
>
We did not check if we have different performance with the extra raw node.
Since in our use case (copying images) small reads/writes are unlikely, I
don't
think it will make a difference.
What is true is that if you use a filename without specifying the driver
> (i.e. you rely on format probing), you'll get a 'raw' node on top of
> the 'file' node.
>
> > oVirt always uses the second form to make it easier to support offset,
> > size, and backing.
> >
> https://github.com/oVirt/ovirt-imageio/blob/2021164d064227d7c5e03c8da087adc66e3a577e/daemon/ovirt_imageio/_internal/qemu_nbd.py#L104
> >
> > This also seems to be the way libvirt builds the nodes using -blockdev.
>
> libvirt actually has a BZ to avoid the 'raw' node for performance when
> it's not needed.
>
> > Do we have a way to visualize the internal node graph used by
> > qemu-nbd/qemu-img?
>
> No, but as long as you explicitly specify the driver, you get exactly
> what you specified.
>
So this is not really needed then.
> For exploring what happens, you can pass the same json: filename to QEMU
> (maybe with -hda) and then use the monitor to inspect the state.
>
> Kevin
>
>
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
` (2 preceding siblings ...)
2020-08-17 17:19 ` Nir Soffer
@ 2020-08-19 19:33 ` Eric Blake
3 siblings, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 19:33 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Instead of implementing qemu-nbd --offset in the NBD code, just put a
> raw block node with the requested offset on top of the user image and
> rely on that doing the job.
>
> This does not only simplify the nbd_export_new() interface and bring it
> closer to the set of options that the nbd-server-add QMP command offers,
> but in fact it also eliminates a potential source for bugs in the NBD
> code which previously had to add the offset manually in all relevant
> places.
Yay! This patch alone is worth having, regardless of the fate of the
rest of the series: no change in end-user functionality, but by making
qemu-nbd turn it into proper syntactic sugar, we've reduced the
maintenance burden of duplicated code.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 4 ++--
> blockdev-nbd.c | 9 +--------
> nbd/server.c | 34 +++++++++++++++++-----------------
> qemu-nbd.c | 27 ++++++++++++---------------
> 4 files changed, 32 insertions(+), 42 deletions(-)
>
> +++ b/nbd/server.c
> @@ -89,7 +89,6 @@ struct NBDExport {
> BlockBackend *blk;
> char *name;
> char *description;
> - uint64_t dev_offset;
> uint64_t size;
I'm trying to figure out if we can also drop 'size' here. If we do, the
consequence would be that an NBD client could ask for beyond-EOF I/O,
and presumably the block layer would reject that gracefully (although
not necessarily with the same errno as NBD currently reports). I'm fine
leaving it alone in this patch, though.
> @@ -1569,7 +1574,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
> exp->nbdflags |= (NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_WRITE_ZEROES |
> NBD_FLAG_SEND_FAST_ZERO);
> }
> - assert(size <= INT64_MAX - dev_offset);
> + assert(size <= INT64_MAX);
As Max caught, this is now dead code.
> @@ -2386,8 +2388,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
> if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
> flags |= BDRV_REQ_NO_FALLBACK;
> }
> - ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset,
> - request->len, flags);
> + ret = blk_pwrite_zeroes(exp->blk, request->from, request->len, flags);
> return nbd_send_generic_reply(client, request->handle, ret,
> "writing to file failed", errp);
>
> @@ -2401,8 +2402,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
> "flush failed", errp);
>
> case NBD_CMD_TRIM:
> - ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset,
> - request->len);
> + ret = blk_co_pdiscard(exp->blk, request->from, request->len);
Merge conflicts with 890cbccb08; should be obvious enough to resolve,
though.
> +++ b/qemu-nbd.c
> @@ -523,7 +523,6 @@ int main(int argc, char **argv)
> const char *port = NULL;
> char *sockpath = NULL;
> char *device = NULL;
> - int64_t fd_size;
> QemuOpts *sn_opts = NULL;
> const char *sn_id_or_name = NULL;
> const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
> @@ -1028,6 +1027,17 @@ int main(int argc, char **argv)
> }
> bs = blk_bs(blk);
>
> + if (dev_offset) {
> + QDict *raw_opts = qdict_new();
> + qdict_put_str(raw_opts, "driver", "raw");
> + qdict_put_str(raw_opts, "file", bs->node_name);
> + qdict_put_int(raw_opts, "offset", dev_offset);
Huh. When 0bc16997f5 got rid of the --partition option, it also got rid
of the only way that the NBD driver could clamp down requests to a range
smaller than the end of the file. Now that you are adding a raw driver
in the mix, that ability to clamp the end of the range (aka a --size
option, in addition to an --offset option) may be worth reinstating.
But that can be done as a separate patch, if at all (and whether
qemu-nbd should do it, or qemu-storage-daemon, or whether we just point
people at 'nbdkit --filter=partition', is part of that discussion). But
for this patch, it looks like you are making a straight-across conversion.
> + bs = bdrv_open(NULL, NULL, raw_opts, flags, &error_fatal);
> + blk_remove_bs(blk);
> + blk_insert_bs(blk, bs, &error_fatal);
> + bdrv_unref(bs);
> + }
> +
Slick.
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (5 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 06/22] qemu-nbd: Use raw block driver for --offset Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 11:41 ` Max Reitz
2020-08-19 19:50 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start Kevin Wolf
` (14 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
nbd-server-add tries to be convenient and adds two questionable
features that we don't want to share in block-export-add, even for NBD
exports:
1. When requesting a writable export of a read-only device, the export
is silently downgraded to read-only. This should be an error in the
context of block-export-add.
2. When using a BlockBackend name, unplugging the device from the guest
will automatically stop the NBD server, too. This may sometimes be
what you want, but it could also be very surprising. Let's keep
things explicit with block-export-add. If the user wants to stop the
export, they should tell us so.
Move these things into the nbd-server-add QMP command handler so that
they apply only there.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/nbd.h | 3 ++-
block/export/export.c | 44 ++++++++++++++++++++++++++++++++++++++-----
blockdev-nbd.c | 10 ++++------
nbd/server.c | 19 ++++++++++++-------
qemu-nbd.c | 3 +--
5 files changed, 58 insertions(+), 21 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 3846d2bac8..ffca3be78f 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -333,7 +333,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
void (*close)(NBDExport *), bool writethrough,
- BlockBackend *on_eject_blk, Error **errp);
+ Error **errp);
+void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
void nbd_export_get(NBDExport *exp);
diff --git a/block/export/export.c b/block/export/export.c
index 3d0dacb3f2..2d5f92861c 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -13,6 +13,8 @@
#include "qemu/osdep.h"
+#include "block/block.h"
+#include "sysemu/block-backend.h"
#include "block/export.h"
#include "block/nbd.h"
#include "qapi/error.h"
@@ -34,24 +36,56 @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
return NULL;
}
-void qmp_block_export_add(BlockExportOptions *export, Error **errp)
+static BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
{
const BlockExportDriver *drv;
drv = blk_exp_find_driver(export->type);
if (!drv) {
error_setg(errp, "No driver found for the requested export type");
- return;
+ return NULL;
}
- drv->create(export, errp);
+ return drv->create(export, errp);
+}
+
+void qmp_block_export_add(BlockExportOptions *export, Error **errp)
+{
+ blk_exp_add(export, errp);
}
void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
{
- BlockExportOptions export = {
+ BlockExport *export;
+ BlockDriverState *bs;
+ BlockBackend *on_eject_blk;
+
+ BlockExportOptions export_opts = {
.type = BLOCK_EXPORT_TYPE_NBD,
.u.nbd = *arg,
};
- qmp_block_export_add(&export, errp);
+
+ /*
+ * nbd-server-add doesn't complain when a read-only device should be
+ * exported as writable, but simply downgrades it. This is an error with
+ * block-export-add.
+ */
+ bs = bdrv_lookup_bs(arg->device, arg->device, NULL);
+ if (bs && bdrv_is_read_only(bs)) {
+ arg->writable = false;
+ }
+
+ export = blk_exp_add(&export_opts, errp);
+ if (!export) {
+ return;
+ }
+
+ /*
+ * nbd-server-add removes the export when the named BlockBackend used for
+ * @device goes away.
+ */
+ on_eject_blk = blk_by_name(arg->device);
+ if (on_eject_blk) {
+ nbd_export_set_on_eject_blk(export, on_eject_blk);
+ }
}
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 16cda3b052..019c37c0bc 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -152,7 +152,6 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
{
BlockExportOptionsNbd *arg = &exp_args->u.nbd;
BlockDriverState *bs = NULL;
- BlockBackend *on_eject_blk;
NBDExport *exp = NULL;
AioContext *aio_context;
@@ -182,8 +181,6 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
return NULL;
}
- on_eject_blk = blk_by_name(arg->device);
-
bs = bdrv_lookup_bs(arg->device, arg->device, errp);
if (!bs) {
return NULL;
@@ -195,13 +192,14 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
if (!arg->has_writable) {
arg->writable = false;
}
- if (bdrv_is_read_only(bs)) {
- arg->writable = false;
+ if (bdrv_is_read_only(bs) && arg->writable) {
+ error_setg(errp, "Cannot export read-only node as writable");
+ goto out;
}
exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
!arg->writable, !arg->writable,
- NULL, false, on_eject_blk, errp);
+ NULL, false, errp);
if (!exp) {
goto out;
}
diff --git a/nbd/server.c b/nbd/server.c
index 92360d1f08..0b84fd30e2 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1506,11 +1506,22 @@ static void nbd_eject_notifier(Notifier *n, void *data)
aio_context_release(aio_context);
}
+void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
+{
+ NBDExport *nbd_exp = container_of(exp, NBDExport, common);
+ assert(exp->drv == &blk_exp_nbd);
+
+ blk_ref(blk);
+ nbd_exp->eject_notifier_blk = blk;
+ nbd_exp->eject_notifier.notify = nbd_eject_notifier;
+ blk_add_remove_bs_notifier(blk, &nbd_exp->eject_notifier);
+}
+
NBDExport *nbd_export_new(BlockDriverState *bs,
const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
void (*close)(NBDExport *), bool writethrough,
- BlockBackend *on_eject_blk, Error **errp)
+ Error **errp)
{
AioContext *ctx;
BlockBackend *blk;
@@ -1618,12 +1629,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
exp->ctx = ctx;
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
- if (on_eject_blk) {
- blk_ref(on_eject_blk);
- exp->eject_notifier_blk = on_eject_blk;
- exp->eject_notifier.notify = nbd_eject_notifier;
- blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
- }
QTAILQ_INSERT_TAIL(&exports, exp, next);
nbd_export_get(exp);
return exp;
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 818c3f5d46..e348d5d6d8 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -1058,8 +1058,7 @@ int main(int argc, char **argv)
export = nbd_export_new(bs, export_name,
export_description, bitmap, readonly, shared > 1,
- nbd_export_closed, writethrough, NULL,
- &error_fatal);
+ nbd_export_closed, writethrough, &error_fatal);
if (device) {
#if HAVE_NBD_DEVICE
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-13 16:29 ` [RFC PATCH 07/22] block/export: Remove magic from block-export-add Kevin Wolf
@ 2020-08-17 11:41 ` Max Reitz
2020-08-17 12:49 ` Kevin Wolf
2020-08-19 19:50 ` Eric Blake
1 sibling, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 11:41 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 4459 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> nbd-server-add tries to be convenient and adds two questionable
> features that we don't want to share in block-export-add, even for NBD
> exports:
>
> 1. When requesting a writable export of a read-only device, the export
> is silently downgraded to read-only. This should be an error in the
> context of block-export-add.
>
> 2. When using a BlockBackend name, unplugging the device from the guest
> will automatically stop the NBD server, too. This may sometimes be
> what you want, but it could also be very surprising. Let's keep
> things explicit with block-export-add. If the user wants to stop the
> export, they should tell us so.
>
> Move these things into the nbd-server-add QMP command handler so that
> they apply only there.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 3 ++-
> block/export/export.c | 44 ++++++++++++++++++++++++++++++++++++++-----
> blockdev-nbd.c | 10 ++++------
> nbd/server.c | 19 ++++++++++++-------
> qemu-nbd.c | 3 +--
> 5 files changed, 58 insertions(+), 21 deletions(-)
[...]
> diff --git a/block/export/export.c b/block/export/export.c
> index 3d0dacb3f2..2d5f92861c 100644
> --- a/block/export/export.c
> +++ b/block/export/export.c
[...]
> @@ -34,24 +36,56 @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
> return NULL;
> }
>
> -void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> +static BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
> {
> const BlockExportDriver *drv;
>
> drv = blk_exp_find_driver(export->type);
> if (!drv) {
> error_setg(errp, "No driver found for the requested export type");
> - return;
> + return NULL;
> }
>
> - drv->create(export, errp);
> + return drv->create(export, errp);
> +}
> +
> +void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> +{
> + blk_exp_add(export, errp);
> }
Interesting. I would have added it this way from the start then (with a
note that we’ll need it later).
> void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> {
> - BlockExportOptions export = {
> + BlockExport *export;
> + BlockDriverState *bs;
> + BlockBackend *on_eject_blk;
> +
> + BlockExportOptions export_opts = {
> .type = BLOCK_EXPORT_TYPE_NBD,
> .u.nbd = *arg,
This copies *arg’s contents...
> };
> - qmp_block_export_add(&export, errp);
> +
> + /*
> + * nbd-server-add doesn't complain when a read-only device should be
> + * exported as writable, but simply downgrades it. This is an error with
> + * block-export-add.
> + */
> + bs = bdrv_lookup_bs(arg->device, arg->device, NULL);
> + if (bs && bdrv_is_read_only(bs)) {
> + arg->writable = false;
...and here you only modify the original *arg, but not
export_opts.u.nbd. So I don’t think this will have any effect.
> + }
> +
> + export = blk_exp_add(&export_opts, errp);
> + if (!export) {
> + return;
> + }
> +
> + /*
> + * nbd-server-add removes the export when the named BlockBackend used for
> + * @device goes away.
> + */
> + on_eject_blk = blk_by_name(arg->device);
> + if (on_eject_blk) {
> + nbd_export_set_on_eject_blk(export, on_eject_blk);
> + }
> }
The longer it gets, the more I think maybe it should be in some NBD file
like blockdev-nbd.c after all.
[...]
> diff --git a/nbd/server.c b/nbd/server.c
> index 92360d1f08..0b84fd30e2 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -1506,11 +1506,22 @@ static void nbd_eject_notifier(Notifier *n, void *data)
> aio_context_release(aio_context);
> }
>
> +void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
> +{
> + NBDExport *nbd_exp = container_of(exp, NBDExport, common);
> + assert(exp->drv == &blk_exp_nbd);
> +
I think asserting that the nbd_exp->eject_notifier is unused so far
would make sense (e.g. just checking that eject_notifier_blk is NULL).
Max
> + blk_ref(blk);
> + nbd_exp->eject_notifier_blk = blk;
> + nbd_exp->eject_notifier.notify = nbd_eject_notifier;
> + blk_add_remove_bs_notifier(blk, &nbd_exp->eject_notifier);
> +}
> +
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-17 11:41 ` Max Reitz
@ 2020-08-17 12:49 ` Kevin Wolf
2020-08-17 13:22 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 12:49 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 4845 bytes --]
Am 17.08.2020 um 13:41 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > nbd-server-add tries to be convenient and adds two questionable
> > features that we don't want to share in block-export-add, even for NBD
> > exports:
> >
> > 1. When requesting a writable export of a read-only device, the export
> > is silently downgraded to read-only. This should be an error in the
> > context of block-export-add.
> >
> > 2. When using a BlockBackend name, unplugging the device from the guest
> > will automatically stop the NBD server, too. This may sometimes be
> > what you want, but it could also be very surprising. Let's keep
> > things explicit with block-export-add. If the user wants to stop the
> > export, they should tell us so.
> >
> > Move these things into the nbd-server-add QMP command handler so that
> > they apply only there.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > include/block/nbd.h | 3 ++-
> > block/export/export.c | 44 ++++++++++++++++++++++++++++++++++++++-----
> > blockdev-nbd.c | 10 ++++------
> > nbd/server.c | 19 ++++++++++++-------
> > qemu-nbd.c | 3 +--
> > 5 files changed, 58 insertions(+), 21 deletions(-)
>
> [...]
>
> > diff --git a/block/export/export.c b/block/export/export.c
> > index 3d0dacb3f2..2d5f92861c 100644
> > --- a/block/export/export.c
> > +++ b/block/export/export.c
>
> [...]
>
> > @@ -34,24 +36,56 @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
> > return NULL;
> > }
> >
> > -void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> > +static BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
> > {
> > const BlockExportDriver *drv;
> >
> > drv = blk_exp_find_driver(export->type);
> > if (!drv) {
> > error_setg(errp, "No driver found for the requested export type");
> > - return;
> > + return NULL;
> > }
> >
> > - drv->create(export, errp);
> > + return drv->create(export, errp);
> > +}
> > +
> > +void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> > +{
> > + blk_exp_add(export, errp);
> > }
>
> Interesting. I would have added it this way from the start then (with a
> note that we’ll need it later).
>
> > void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> > {
> > - BlockExportOptions export = {
> > + BlockExport *export;
> > + BlockDriverState *bs;
> > + BlockBackend *on_eject_blk;
> > +
> > + BlockExportOptions export_opts = {
> > .type = BLOCK_EXPORT_TYPE_NBD,
> > .u.nbd = *arg,
>
> This copies *arg’s contents...
>
> > };
> > - qmp_block_export_add(&export, errp);
> > +
> > + /*
> > + * nbd-server-add doesn't complain when a read-only device should be
> > + * exported as writable, but simply downgrades it. This is an error with
> > + * block-export-add.
> > + */
> > + bs = bdrv_lookup_bs(arg->device, arg->device, NULL);
> > + if (bs && bdrv_is_read_only(bs)) {
> > + arg->writable = false;
>
> ...and here you only modify the original *arg, but not
> export_opts.u.nbd. So I don’t think this will have any effect.
I thought I had tested this... Well, good catch, thanks.
> > + }
> > +
> > + export = blk_exp_add(&export_opts, errp);
> > + if (!export) {
> > + return;
> > + }
> > +
> > + /*
> > + * nbd-server-add removes the export when the named BlockBackend used for
> > + * @device goes away.
> > + */
> > + on_eject_blk = blk_by_name(arg->device);
> > + if (on_eject_blk) {
> > + nbd_export_set_on_eject_blk(export, on_eject_blk);
> > + }
> > }
>
> The longer it gets, the more I think maybe it should be in some NBD file
> like blockdev-nbd.c after all.
Fair enough. Though I think blockdev-nbd.c in the root directory is
something that shouldn't even exist.
But I guess I can just leave the functions where they are and we can
move the file another day.
> [...]
>
> > diff --git a/nbd/server.c b/nbd/server.c
> > index 92360d1f08..0b84fd30e2 100644
> > --- a/nbd/server.c
> > +++ b/nbd/server.c
> > @@ -1506,11 +1506,22 @@ static void nbd_eject_notifier(Notifier *n, void *data)
> > aio_context_release(aio_context);
> > }
> >
> > +void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
> > +{
> > + NBDExport *nbd_exp = container_of(exp, NBDExport, common);
> > + assert(exp->drv == &blk_exp_nbd);
> > +
>
> I think asserting that the nbd_exp->eject_notifier is unused so far
> would make sense (e.g. just checking that eject_notifier_blk is NULL).
Makes sense.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-17 12:49 ` Kevin Wolf
@ 2020-08-17 13:22 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 13:22 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 2133 bytes --]
On 17.08.20 14:49, Kevin Wolf wrote:
> Am 17.08.2020 um 13:41 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> nbd-server-add tries to be convenient and adds two questionable
>>> features that we don't want to share in block-export-add, even for NBD
>>> exports:
>>>
>>> 1. When requesting a writable export of a read-only device, the export
>>> is silently downgraded to read-only. This should be an error in the
>>> context of block-export-add.
>>>
>>> 2. When using a BlockBackend name, unplugging the device from the guest
>>> will automatically stop the NBD server, too. This may sometimes be
>>> what you want, but it could also be very surprising. Let's keep
>>> things explicit with block-export-add. If the user wants to stop the
>>> export, they should tell us so.
>>>
>>> Move these things into the nbd-server-add QMP command handler so that
>>> they apply only there.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> include/block/nbd.h | 3 ++-
>>> block/export/export.c | 44 ++++++++++++++++++++++++++++++++++++++-----
>>> blockdev-nbd.c | 10 ++++------
>>> nbd/server.c | 19 ++++++++++++-------
>>> qemu-nbd.c | 3 +--
>>> 5 files changed, 58 insertions(+), 21 deletions(-)
[...]
>>> + }
>>> +
>>> + export = blk_exp_add(&export_opts, errp);
>>> + if (!export) {
>>> + return;
>>> + }
>>> +
>>> + /*
>>> + * nbd-server-add removes the export when the named BlockBackend used for
>>> + * @device goes away.
>>> + */
>>> + on_eject_blk = blk_by_name(arg->device);
>>> + if (on_eject_blk) {
>>> + nbd_export_set_on_eject_blk(export, on_eject_blk);
>>> + }
>>> }
>>
>> The longer it gets, the more I think maybe it should be in some NBD file
>> like blockdev-nbd.c after all.
>
> Fair enough. Though I think blockdev-nbd.c in the root directory is
> something that shouldn't even exist.
Absolutely. But unless you (or someone™ else) doesn’t do anything about
it, we may as well continue to (ab)use it. O:)
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-13 16:29 ` [RFC PATCH 07/22] block/export: Remove magic from block-export-add Kevin Wolf
2020-08-17 11:41 ` Max Reitz
@ 2020-08-19 19:50 ` Eric Blake
2020-08-20 11:05 ` Kevin Wolf
1 sibling, 1 reply; 90+ messages in thread
From: Eric Blake @ 2020-08-19 19:50 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: Peter Krempa, qemu-devel, mreitz
cc: Peter Krempa
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> nbd-server-add tries to be convenient and adds two questionable
> features that we don't want to share in block-export-add, even for NBD
> exports:
>
> 1. When requesting a writable export of a read-only device, the export
> is silently downgraded to read-only. This should be an error in the
> context of block-export-add.
I'd be happy for this to be an error even with nbd-export-add; I don't
think it would harm any of libvirt's existing usage (either for storage
migration, or for incremental backups).
Side note: In the past, I had a proposal to enhance the NBD Protocol to
allow a client to advertise to the server its intent on being a
read-only or read-write client. Not relevant to this patch, but this
part of the commit message reminds me that I should revisit that topic
(Rich and I recently hit another case in nbdkit where such an extension
would be nice, when it comes to using NBD's multi-conn for better
performance on a read-only connection, but only if the server knows the
client intends to be read-only)
>
> 2. When using a BlockBackend name, unplugging the device from the guest
> will automatically stop the NBD server, too. This may sometimes be
> what you want, but it could also be very surprising. Let's keep
> things explicit with block-export-add. If the user wants to stop the
> export, they should tell us so.
Here, keeping the nbd command different from the block-export command
seems tolerable. On the other hand, I wonder if Peter needs to change
anything in libvirt's incremental backup code to handle this sudden
disappearance of an NBD device during a disk hot-unplug (that is, either
the presence of an ongoing pull-mode backup should block disk unplug, or
libvirt needs a way to guarantee that an ongoing backup NBD device
remains in spite of subsequent disk actions on the guest). Depending on
libvirt's needs, we may want to revisit the nbd command to have the same
policy as block-export-add, plus an introspectible feature notation.
>
> Move these things into the nbd-server-add QMP command handler so that
> they apply only there.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 3 ++-
> +void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> +{
> + blk_exp_add(export, errp);
> }
>
> void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> {
> - BlockExportOptions export = {
> + BlockExport *export;
> + BlockDriverState *bs;
> + BlockBackend *on_eject_blk;
> +
> + BlockExportOptions export_opts = {
> .type = BLOCK_EXPORT_TYPE_NBD,
> .u.nbd = *arg,
> };
> - qmp_block_export_add(&export, errp);
> +
> + /*
> + * nbd-server-add doesn't complain when a read-only device should be
> + * exported as writable, but simply downgrades it. This is an error with
> + * block-export-add.
I'd be happy with either marking this deprecated now (and fixing it in
two releases), or declaring it a bug in nbd-server-add now (and fixing
it outright).
> + */
> + bs = bdrv_lookup_bs(arg->device, arg->device, NULL);
> + if (bs && bdrv_is_read_only(bs)) {
> + arg->writable = false;
> + }
> +
> + export = blk_exp_add(&export_opts, errp);
> + if (!export) {
> + return;
> + }
> +
> + /*
> + * nbd-server-add removes the export when the named BlockBackend used for
> + * @device goes away.
> + */
> + on_eject_blk = blk_by_name(arg->device);
> + if (on_eject_blk) {
> + nbd_export_set_on_eject_blk(export, on_eject_blk);
> + }
Wait - is the magic export removal tied only to exporting a drive name,
and not a node name? So as long as libvirt is using only node names
whwen adding exports, a drive being unplugged won't interfere?
Overall, the change makes sense to me, although I'd love to see if we
could go further on the writable vs. read-only issue.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-19 19:50 ` Eric Blake
@ 2020-08-20 11:05 ` Kevin Wolf
2020-08-20 14:41 ` Eric Blake
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-20 11:05 UTC (permalink / raw)
To: Eric Blake; +Cc: Peter Krempa, qemu-devel, qemu-block, mreitz
Am 19.08.2020 um 21:50 hat Eric Blake geschrieben:
> cc: Peter Krempa
>
> On 8/13/20 11:29 AM, Kevin Wolf wrote:
> > nbd-server-add tries to be convenient and adds two questionable
> > features that we don't want to share in block-export-add, even for NBD
> > exports:
> >
> > 1. When requesting a writable export of a read-only device, the export
> > is silently downgraded to read-only. This should be an error in the
> > context of block-export-add.
>
> I'd be happy for this to be an error even with nbd-export-add; I don't think
> it would harm any of libvirt's existing usage (either for storage migration,
> or for incremental backups).
>
> Side note: In the past, I had a proposal to enhance the NBD Protocol to
> allow a client to advertise to the server its intent on being a read-only or
> read-write client. Not relevant to this patch, but this part of the commit
> message reminds me that I should revisit that topic (Rich and I recently hit
> another case in nbdkit where such an extension would be nice, when it comes
> to using NBD's multi-conn for better performance on a read-only connection,
> but only if the server knows the client intends to be read-only)
>
> >
> > 2. When using a BlockBackend name, unplugging the device from the guest
> > will automatically stop the NBD server, too. This may sometimes be
> > what you want, but it could also be very surprising. Let's keep
> > things explicit with block-export-add. If the user wants to stop the
> > export, they should tell us so.
>
> Here, keeping the nbd command different from the block-export command seems
> tolerable. On the other hand, I wonder if Peter needs to change anything in
> libvirt's incremental backup code to handle this sudden disappearance of an
> NBD device during a disk hot-unplug (that is, either the presence of an
> ongoing pull-mode backup should block disk unplug, or libvirt needs a way to
> guarantee that an ongoing backup NBD device remains in spite of subsequent
> disk actions on the guest). Depending on libvirt's needs, we may want to
> revisit the nbd command to have the same policy as block-export-add, plus an
> introspectible feature notation.
As long as we can keep the compatibility code local to qmp_nbd_*(), I
don't think it's too bad. In particular because it's already written.
Instead of adjusting libvirt to changes in the nbd-* commands, I'd
rather have it change over to block-export-*. I would like to see the
nbd-server-add/remove commands deprecated soon after we have the
replacements.
> >
> > Move these things into the nbd-server-add QMP command handler so that
> > they apply only there.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > include/block/nbd.h | 3 ++-
>
> > +void qmp_block_export_add(BlockExportOptions *export, Error **errp)
> > +{
> > + blk_exp_add(export, errp);
> > }
> > void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
> > {
> > - BlockExportOptions export = {
> > + BlockExport *export;
> > + BlockDriverState *bs;
> > + BlockBackend *on_eject_blk;
> > +
> > + BlockExportOptions export_opts = {
> > .type = BLOCK_EXPORT_TYPE_NBD,
> > .u.nbd = *arg,
> > };
> > - qmp_block_export_add(&export, errp);
> > +
> > + /*
> > + * nbd-server-add doesn't complain when a read-only device should be
> > + * exported as writable, but simply downgrades it. This is an error with
> > + * block-export-add.
>
> I'd be happy with either marking this deprecated now (and fixing it in two
> releases), or declaring it a bug in nbd-server-add now (and fixing it
> outright).
How about deprecating nbd-server-add completely?
> > + */
> > + bs = bdrv_lookup_bs(arg->device, arg->device, NULL);
> > + if (bs && bdrv_is_read_only(bs)) {
> > + arg->writable = false;
> > + }
> > +
> > + export = blk_exp_add(&export_opts, errp);
> > + if (!export) {
> > + return;
> > + }
> > +
> > + /*
> > + * nbd-server-add removes the export when the named BlockBackend used for
> > + * @device goes away.
> > + */
> > + on_eject_blk = blk_by_name(arg->device);
> > + if (on_eject_blk) {
> > + nbd_export_set_on_eject_blk(export, on_eject_blk);
> > + }
>
> Wait - is the magic export removal tied only to exporting a drive name, and
> not a node name? So as long as libvirt is using only node names whwen
> adding exports, a drive being unplugged won't interfere?
Yes, seems so. It's the existing behaviour, I'm only moving the code
around.
> Overall, the change makes sense to me, although I'd love to see if we could
> go further on the writable vs. read-only issue.
If nbd-server-add will be going away relatively soon, it's probably not
worth the trouble. But if you have reasons to keep it, maybe we should
consider it.
Kevin
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-20 11:05 ` Kevin Wolf
@ 2020-08-20 14:41 ` Eric Blake
2020-08-20 15:28 ` Peter Krempa
0 siblings, 1 reply; 90+ messages in thread
From: Eric Blake @ 2020-08-20 14:41 UTC (permalink / raw)
To: Kevin Wolf; +Cc: Peter Krempa, qemu-devel, qemu-block, mreitz
On 8/20/20 6:05 AM, Kevin Wolf wrote:
> As long as we can keep the compatibility code local to qmp_nbd_*(), I
> don't think it's too bad. In particular because it's already written.
>
> Instead of adjusting libvirt to changes in the nbd-* commands, I'd
> rather have it change over to block-export-*. I would like to see the
> nbd-server-add/remove commands deprecated soon after we have the
> replacements.
Makes sense to me. So deprecate nbd-server-add in 5.2, and require
block-export in 6.1.
>>> + /*
>>> + * nbd-server-add doesn't complain when a read-only device should be
>>> + * exported as writable, but simply downgrades it. This is an error with
>>> + * block-export-add.
>>
>> I'd be happy with either marking this deprecated now (and fixing it in two
>> releases), or declaring it a bug in nbd-server-add now (and fixing it
>> outright).
>
> How about deprecating nbd-server-add completely?
Works for me. Keeping the warts backwards-compatible in nbd-server-add
is more palatable if we know we are going to drop it wholesale down the
road.
>>> + /*
>>> + * nbd-server-add removes the export when the named BlockBackend used for
>>> + * @device goes away.
>>> + */
>>> + on_eject_blk = blk_by_name(arg->device);
>>> + if (on_eject_blk) {
>>> + nbd_export_set_on_eject_blk(export, on_eject_blk);
>>> + }
>>
>> Wait - is the magic export removal tied only to exporting a drive name, and
>> not a node name? So as long as libvirt is using only node names whwen
>> adding exports, a drive being unplugged won't interfere?
>
> Yes, seems so. It's the existing behaviour, I'm only moving the code
> around.
>
>> Overall, the change makes sense to me, although I'd love to see if we could
>> go further on the writable vs. read-only issue.
>
> If nbd-server-add will be going away relatively soon, it's probably not
> worth the trouble. But if you have reasons to keep it, maybe we should
> consider it.
No, I'm fine with the idea of getting rid of nbd-server-add, at which
point changing it before removal is pointless.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 07/22] block/export: Remove magic from block-export-add
2020-08-20 14:41 ` Eric Blake
@ 2020-08-20 15:28 ` Peter Krempa
0 siblings, 0 replies; 90+ messages in thread
From: Peter Krempa @ 2020-08-20 15:28 UTC (permalink / raw)
To: Eric Blake; +Cc: Kevin Wolf, qemu-devel, qemu-block, mreitz
On Thu, Aug 20, 2020 at 09:41:14 -0500, Eric Blake wrote:
> On 8/20/20 6:05 AM, Kevin Wolf wrote:
>
> > As long as we can keep the compatibility code local to qmp_nbd_*(), I
> > don't think it's too bad. In particular because it's already written.
> >
> > Instead of adjusting libvirt to changes in the nbd-* commands, I'd
> > rather have it change over to block-export-*. I would like to see the
> > nbd-server-add/remove commands deprecated soon after we have the
> > replacements.
>
> Makes sense to me. So deprecate nbd-server-add in 5.2, and require
> block-export in 6.1.
>
>
> > > > + /*
> > > > + * nbd-server-add doesn't complain when a read-only device should be
> > > > + * exported as writable, but simply downgrades it. This is an error with
> > > > + * block-export-add.
> > >
> > > I'd be happy with either marking this deprecated now (and fixing it in two
> > > releases), or declaring it a bug in nbd-server-add now (and fixing it
> > > outright).
> >
> > How about deprecating nbd-server-add completely?
>
> Works for me. Keeping the warts backwards-compatible in nbd-server-add is
> more palatable if we know we are going to drop it wholesale down the road.
>
> > > > + /*
> > > > + * nbd-server-add removes the export when the named BlockBackend used for
> > > > + * @device goes away.
> > > > + */
> > > > + on_eject_blk = blk_by_name(arg->device);
> > > > + if (on_eject_blk) {
> > > > + nbd_export_set_on_eject_blk(export, on_eject_blk);
> > > > + }
> > >
> > > Wait - is the magic export removal tied only to exporting a drive name, and
> > > not a node name? So as long as libvirt is using only node names whwen
> > > adding exports, a drive being unplugged won't interfere?
> >
> > Yes, seems so. It's the existing behaviour, I'm only moving the code
> > around.
> >
> > > Overall, the change makes sense to me, although I'd love to see if we could
> > > go further on the writable vs. read-only issue.
> >
> > If nbd-server-add will be going away relatively soon, it's probably not
> > worth the trouble. But if you have reasons to keep it, maybe we should
> > consider it.
>
> No, I'm fine with the idea of getting rid of nbd-server-add, at which point
> changing it before removal is pointless.
I agree that this is a better approach. While it's technically possible
to retrofit old commands since QMP schema introspection allows granilar
detection of what's happening in this regard using a new command is IMO
better. Specifically for APPS which might not use QMP introspection to
the extent libvirt does.
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (6 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 07/22] block/export: Remove magic from block-export-add Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 12:37 ` Max Reitz
2020-08-19 20:00 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 09/22] nbd: Add writethrough to block-export-add Kevin Wolf
` (13 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
This is a QMP equivalent of qemu-nbd's --share option, limiting the
maximum number of clients that can attach at the same time.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 10 ++++++++--
include/block/nbd.h | 3 ++-
block/monitor/block-hmp-cmds.c | 2 +-
blockdev-nbd.c | 33 ++++++++++++++++++++++++++-------
qemu-storage-daemon.c | 4 ++--
5 files changed, 39 insertions(+), 13 deletions(-)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 40369814b4..1fdc55c53a 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -14,6 +14,8 @@
# is only resolved at time of use, so can be deleted and
# recreated on the fly while the NBD server is active.
# If missing, it will default to denying access (since 4.0).
+# @max-connections: The maximum number of connections to allow at the same
+# time, 0 for unlimited. (since 5.2; default: 0)
#
# Keep this type consistent with the nbd-server-start arguments. The only
# intended difference is using SocketAddress instead of SocketAddressLegacy.
@@ -23,7 +25,8 @@
{ 'struct': 'NbdServerOptions',
'data': { 'addr': 'SocketAddress',
'*tls-creds': 'str',
- '*tls-authz': 'str'} }
+ '*tls-authz': 'str',
+ '*max-connections': 'uint32' } }
##
# @nbd-server-start:
@@ -40,6 +43,8 @@
# is only resolved at time of use, so can be deleted and
# recreated on the fly while the NBD server is active.
# If missing, it will default to denying access (since 4.0).
+# @max-connections: The maximum number of connections to allow at the same
+# time, 0 for unlimited. (since 5.2; default: 0)
#
# Returns: error if the server is already running.
#
@@ -51,7 +56,8 @@
{ 'command': 'nbd-server-start',
'data': { 'addr': 'SocketAddressLegacy',
'*tls-creds': 'str',
- '*tls-authz': 'str'} }
+ '*tls-authz': 'str',
+ '*max-connections': 'uint32' } }
##
# @BlockExportOptionsNbd:
diff --git a/include/block/nbd.h b/include/block/nbd.h
index ffca3be78f..6fc1f05ef4 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -352,7 +352,8 @@ void nbd_client_get(NBDClient *client);
void nbd_client_put(NBDClient *client);
void nbd_server_start(SocketAddress *addr, const char *tls_creds,
- const char *tls_authz, Error **errp);
+ const char *tls_authz, uint32_t max_connections,
+ Error **errp);
void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
/* nbd_read
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index 56bc83ac97..a651954e16 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -411,7 +411,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
goto exit;
}
- nbd_server_start(addr, NULL, NULL, &local_err);
+ nbd_server_start(addr, NULL, NULL, 0, &local_err);
qapi_free_SocketAddress(addr);
if (local_err != NULL) {
goto exit;
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 019c37c0bc..28159a92b2 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -23,23 +23,41 @@ typedef struct NBDServerData {
QIONetListener *listener;
QCryptoTLSCreds *tlscreds;
char *tlsauthz;
+ uint32_t max_connections;
+ uint32_t connections;
} NBDServerData;
static NBDServerData *nbd_server;
+static void nbd_update_server_watch(NBDServerData *s);
+
static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
{
nbd_client_put(client);
+ assert(nbd_server->connections > 0);
+ nbd_server->connections--;
+ nbd_update_server_watch(nbd_server);
}
static void nbd_accept(QIONetListener *listener, QIOChannelSocket *cioc,
gpointer opaque)
{
+ nbd_server->connections++;
+ nbd_update_server_watch(nbd_server);
+
qio_channel_set_name(QIO_CHANNEL(cioc), "nbd-server");
nbd_client_new(cioc, nbd_server->tlscreds, nbd_server->tlsauthz,
nbd_blockdev_client_closed);
}
+static void nbd_update_server_watch(NBDServerData *s)
+{
+ if (!s->max_connections || s->connections < s->max_connections) {
+ qio_net_listener_set_client_func(s->listener, nbd_accept, NULL, NULL);
+ } else {
+ qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL);
+ }
+}
static void nbd_server_free(NBDServerData *server)
{
@@ -88,7 +106,8 @@ static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
void nbd_server_start(SocketAddress *addr, const char *tls_creds,
- const char *tls_authz, Error **errp)
+ const char *tls_authz, uint32_t max_connections,
+ Error **errp)
{
if (nbd_server) {
error_setg(errp, "NBD server already running");
@@ -96,6 +115,7 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds,
}
nbd_server = g_new0(NBDServerData, 1);
+ nbd_server->max_connections = max_connections;
nbd_server->listener = qio_net_listener_new();
qio_net_listener_set_name(nbd_server->listener,
@@ -120,10 +140,7 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds,
nbd_server->tlsauthz = g_strdup(tls_authz);
- qio_net_listener_set_client_func(nbd_server->listener,
- nbd_accept,
- NULL,
- NULL);
+ nbd_update_server_watch(nbd_server);
return;
@@ -134,17 +151,19 @@ void nbd_server_start(SocketAddress *addr, const char *tls_creds,
void nbd_server_start_options(NbdServerOptions *arg, Error **errp)
{
- nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz, errp);
+ nbd_server_start(arg->addr, arg->tls_creds, arg->tls_authz,
+ arg->max_connections, errp);
}
void qmp_nbd_server_start(SocketAddressLegacy *addr,
bool has_tls_creds, const char *tls_creds,
bool has_tls_authz, const char *tls_authz,
+ bool has_max_connections, uint32_t max_connections,
Error **errp)
{
SocketAddress *addr_flat = socket_address_flatten(addr);
- nbd_server_start(addr_flat, tls_creds, tls_authz, errp);
+ nbd_server_start(addr_flat, tls_creds, tls_authz, max_connections, errp);
qapi_free_SocketAddress(addr_flat);
}
diff --git a/qemu-storage-daemon.c b/qemu-storage-daemon.c
index b6f678d3ab..0fcab6ed2d 100644
--- a/qemu-storage-daemon.c
+++ b/qemu-storage-daemon.c
@@ -101,9 +101,9 @@ static void help(void)
" configure a QMP monitor\n"
"\n"
" --nbd-server addr.type=inet,addr.host=<host>,addr.port=<port>\n"
-" [,tls-creds=<id>][,tls-authz=<id>]\n"
+" [,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]\n"
" --nbd-server addr.type=unix,addr.path=<path>\n"
-" [,tls-creds=<id>][,tls-authz=<id>]\n"
+" [,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]\n"
" start an NBD server for exporting block nodes\n"
"\n"
" --object help list object types that can be added\n"
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start
2020-08-13 16:29 ` [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start Kevin Wolf
@ 2020-08-17 12:37 ` Max Reitz
2020-08-17 13:01 ` Kevin Wolf
2020-08-19 20:00 ` Eric Blake
1 sibling, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 12:37 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 676 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> This is a QMP equivalent of qemu-nbd's --share option, limiting the
*--shared
> maximum number of clients that can attach at the same time.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 10 ++++++++--
> include/block/nbd.h | 3 ++-
> block/monitor/block-hmp-cmds.c | 2 +-
> blockdev-nbd.c | 33 ++++++++++++++++++++++++++-------
> qemu-storage-daemon.c | 4 ++--
> 5 files changed, 39 insertions(+), 13 deletions(-)
I suppose this is part of this series so that patch 11 can happen?
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start
2020-08-17 12:37 ` Max Reitz
@ 2020-08-17 13:01 ` Kevin Wolf
0 siblings, 0 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 13:01 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 987 bytes --]
Am 17.08.2020 um 14:37 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > This is a QMP equivalent of qemu-nbd's --share option, limiting the
>
> *--shared
>
> > maximum number of clients that can attach at the same time.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 10 ++++++++--
> > include/block/nbd.h | 3 ++-
> > block/monitor/block-hmp-cmds.c | 2 +-
> > blockdev-nbd.c | 33 ++++++++++++++++++++++++++-------
> > qemu-storage-daemon.c | 4 ++--
> > 5 files changed, 39 insertions(+), 13 deletions(-)
>
> I suppose this is part of this series so that patch 11 can happen?
More like because initially I thought it would be needed for patch 11,
and when I realised that server != export and it's not really needed, I
still didn't want to throw the patch away...
I could make it a patch separate from this series if that's helpful.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start
2020-08-13 16:29 ` [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start Kevin Wolf
2020-08-17 12:37 ` Max Reitz
@ 2020-08-19 20:00 ` Eric Blake
2020-08-20 11:12 ` Kevin Wolf
1 sibling, 1 reply; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:00 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> This is a QMP equivalent of qemu-nbd's --share option, limiting the
> maximum number of clients that can attach at the same time.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 10 ++++++++--
> include/block/nbd.h | 3 ++-
> block/monitor/block-hmp-cmds.c | 2 +-
> blockdev-nbd.c | 33 ++++++++++++++++++++++++++-------
> qemu-storage-daemon.c | 4 ++--
> 5 files changed, 39 insertions(+), 13 deletions(-)
>
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index 40369814b4..1fdc55c53a 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -14,6 +14,8 @@
> # is only resolved at time of use, so can be deleted and
> # recreated on the fly while the NBD server is active.
> # If missing, it will default to denying access (since 4.0).
> +# @max-connections: The maximum number of connections to allow at the same
> +# time, 0 for unlimited. (since 5.2; default: 0)
Nice way to add feature parity.
Limiting the number of connections (particularly for a writable client,
where we cannot guarantee cache consistency between the connections),
seems like a worthwhile feature to have; I've always found it odd that
qemu-nbd and QMP nbd-server-add defaulted to different limits (1 vs.
unlimited). For reference, nbdkit defaults to unlimited, and I'm happy
if qemu-storage-daemon does likewise; but changing qemu-nbd's default of
1 would be backwards incompatible and may cause surprises (there's
always 'qemu-nbd -e' when needed). I also wonder if we should change
'qemu-nbd -e 0' to mean unlimited rather than an error (right now,
qemu-iotests/common.rc uses -e 42 for all nbd-based tests for a saner
limit than just 1, but it smells of being arbitrary compared to unlimited).
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start
2020-08-19 20:00 ` Eric Blake
@ 2020-08-20 11:12 ` Kevin Wolf
0 siblings, 0 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-20 11:12 UTC (permalink / raw)
To: Eric Blake; +Cc: qemu-devel, qemu-block, mreitz
Am 19.08.2020 um 22:00 hat Eric Blake geschrieben:
> On 8/13/20 11:29 AM, Kevin Wolf wrote:
> > This is a QMP equivalent of qemu-nbd's --share option, limiting the
> > maximum number of clients that can attach at the same time.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 10 ++++++++--
> > include/block/nbd.h | 3 ++-
> > block/monitor/block-hmp-cmds.c | 2 +-
> > blockdev-nbd.c | 33 ++++++++++++++++++++++++++-------
> > qemu-storage-daemon.c | 4 ++--
> > 5 files changed, 39 insertions(+), 13 deletions(-)
> >
> > diff --git a/qapi/block-export.json b/qapi/block-export.json
> > index 40369814b4..1fdc55c53a 100644
> > --- a/qapi/block-export.json
> > +++ b/qapi/block-export.json
> > @@ -14,6 +14,8 @@
> > # is only resolved at time of use, so can be deleted and
> > # recreated on the fly while the NBD server is active.
> > # If missing, it will default to denying access (since 4.0).
> > +# @max-connections: The maximum number of connections to allow at the same
> > +# time, 0 for unlimited. (since 5.2; default: 0)
>
> Nice way to add feature parity.
>
> Limiting the number of connections (particularly for a writable client,
> where we cannot guarantee cache consistency between the connections), seems
> like a worthwhile feature to have; I've always found it odd that qemu-nbd
> and QMP nbd-server-add defaulted to different limits (1 vs. unlimited). For
> reference, nbdkit defaults to unlimited, and I'm happy if
> qemu-storage-daemon does likewise; but changing qemu-nbd's default of 1
> would be backwards incompatible and may cause surprises (there's always
> 'qemu-nbd -e' when needed). I also wonder if we should change 'qemu-nbd -e
> 0' to mean unlimited rather than an error (right now, qemu-iotests/common.rc
> uses -e 42 for all nbd-based tests for a saner limit than just 1, but it
> smells of being arbitrary compared to unlimited).
I think eventually the actual NBD server implementation in qemu-nbd
should go away and it should just reuse the QMP one. Changing the
default would remove one more difference between them, which can only be
helpful in this process. (Though of course having a different default is
still simple enough for a simple wrapper.)
Kevin
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (7 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 08/22] nbd: Add max-connections to nbd-server-start Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 12:56 ` Max Reitz
2020-08-19 20:13 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 10/22] nbd: Remove NBDExport.close callback Kevin Wolf
` (12 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
qemu-nbd allows use of writethrough cache modes, which mean that write
requests made through NBD will cause a flush before they complete.
Expose the same functionality in block-export-add.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 7 ++++++-
blockdev-nbd.c | 2 +-
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 1fdc55c53a..4ce163411f 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -167,10 +167,15 @@
# Describes a block export, i.e. how single node should be exported on an
# external interface.
#
+# @writethrough: If true, caches are flushed after every write request to the
+# export before completion is signalled. (since: 5.2;
+# default: false)
+#
# Since: 4.2
##
{ 'union': 'BlockExportOptions',
- 'base': { 'type': 'BlockExportType' },
+ 'base': { 'type': 'BlockExportType',
+ '*writethrough': 'bool' },
'discriminator': 'type',
'data': {
'nbd': 'BlockExportOptionsNbd'
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 28159a92b2..17417c1b6b 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -218,7 +218,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
!arg->writable, !arg->writable,
- NULL, false, errp);
+ NULL, exp_args->writethrough, errp);
if (!exp) {
goto out;
}
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-13 16:29 ` [RFC PATCH 09/22] nbd: Add writethrough to block-export-add Kevin Wolf
@ 2020-08-17 12:56 ` Max Reitz
2020-08-17 13:13 ` Kevin Wolf
2020-08-19 20:05 ` Eric Blake
2020-08-19 20:13 ` Eric Blake
1 sibling, 2 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 12:56 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 2248 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> qemu-nbd allows use of writethrough cache modes, which mean that write
> requests made through NBD will cause a flush before they complete.
> Expose the same functionality in block-export-add.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 7 ++++++-
> blockdev-nbd.c | 2 +-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index 1fdc55c53a..4ce163411f 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -167,10 +167,15 @@
> # Describes a block export, i.e. how single node should be exported on an
> # external interface.
> #
> +# @writethrough: If true, caches are flushed after every write request to the
> +# export before completion is signalled. (since: 5.2;
> +# default: false)
> +#
> # Since: 4.2
> ##
> { 'union': 'BlockExportOptions',
> - 'base': { 'type': 'BlockExportType' },
> + 'base': { 'type': 'BlockExportType',
> + '*writethrough': 'bool' },
> 'discriminator': 'type',
> 'data': {
> 'nbd': 'BlockExportOptionsNbd'
Hm. I find it weird to have @writethrough in the base but @device in
the specialized class.
I think everything that will be common to all block exports should be in
the base, and that probably includes a node-name. I’m aware that will
make things more tedious in the code, but perhaps it would be a nicer
interface in the end. Or is the real problem that that would create
problems in the storage daemon’s command line interface, because then
the specialized (legacy) NBD interface would no longer be compatible
with the new generalized block export interface?
Anyway, @writable might be a similar story. A @read-only may make sense
in general, I think.
Basically, I think that the export code should be separate from the code
setting up the BlockBackend that should be exported, so all options
regarding that BB should be common; and those options are @node-name,
@writethrough, and @read-only. (And perhaps other things like
@resizable, too, even though that isn’t something to consider for NBD.)
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-17 12:56 ` Max Reitz
@ 2020-08-17 13:13 ` Kevin Wolf
2020-08-17 13:51 ` Max Reitz
2020-08-19 20:05 ` Eric Blake
1 sibling, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 13:13 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 2905 bytes --]
Am 17.08.2020 um 14:56 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > qemu-nbd allows use of writethrough cache modes, which mean that write
> > requests made through NBD will cause a flush before they complete.
> > Expose the same functionality in block-export-add.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 7 ++++++-
> > blockdev-nbd.c | 2 +-
> > 2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/qapi/block-export.json b/qapi/block-export.json
> > index 1fdc55c53a..4ce163411f 100644
> > --- a/qapi/block-export.json
> > +++ b/qapi/block-export.json
> > @@ -167,10 +167,15 @@
> > # Describes a block export, i.e. how single node should be exported on an
> > # external interface.
> > #
> > +# @writethrough: If true, caches are flushed after every write request to the
> > +# export before completion is signalled. (since: 5.2;
> > +# default: false)
> > +#
> > # Since: 4.2
> > ##
> > { 'union': 'BlockExportOptions',
> > - 'base': { 'type': 'BlockExportType' },
> > + 'base': { 'type': 'BlockExportType',
> > + '*writethrough': 'bool' },
> > 'discriminator': 'type',
> > 'data': {
> > 'nbd': 'BlockExportOptionsNbd'
>
> Hm. I find it weird to have @writethrough in the base but @device in
> the specialized class.
>
> I think everything that will be common to all block exports should be in
> the base, and that probably includes a node-name. I’m aware that will
> make things more tedious in the code, but perhaps it would be a nicer
> interface in the end. Or is the real problem that that would create
> problems in the storage daemon’s command line interface, because then
> the specialized (legacy) NBD interface would no longer be compatible
> with the new generalized block export interface?
Indeed. I think patch 15 has what you're looking for.
> Anyway, @writable might be a similar story. A @read-only may make sense
> in general, I think.
Pulling @writable up is easier than a @read-only, but that's a naming
detail.
In general I agree, but this part isn't addressed in this series yet.
Part of the reason why this is an RFC was to find out if I should
include things like this or if we'll do it when we add another export
type or common functionality that needs the same option.
> Basically, I think that the export code should be separate from the code
> setting up the BlockBackend that should be exported, so all options
> regarding that BB should be common; and those options are @node-name,
> @writethrough, and @read-only. (And perhaps other things like
> @resizable, too, even though that isn’t something to consider for NBD.)
Do you mean that the BlockBackend should already be created by the
generic block export layer?
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-17 13:13 ` Kevin Wolf
@ 2020-08-17 13:51 ` Max Reitz
2020-08-17 14:32 ` Kevin Wolf
0 siblings, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 13:51 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 5286 bytes --]
On 17.08.20 15:13, Kevin Wolf wrote:
> Am 17.08.2020 um 14:56 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> qemu-nbd allows use of writethrough cache modes, which mean that write
>>> requests made through NBD will cause a flush before they complete.
>>> Expose the same functionality in block-export-add.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> qapi/block-export.json | 7 ++++++-
>>> blockdev-nbd.c | 2 +-
>>> 2 files changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/qapi/block-export.json b/qapi/block-export.json
>>> index 1fdc55c53a..4ce163411f 100644
>>> --- a/qapi/block-export.json
>>> +++ b/qapi/block-export.json
>>> @@ -167,10 +167,15 @@
>>> # Describes a block export, i.e. how single node should be exported on an
>>> # external interface.
>>> #
>>> +# @writethrough: If true, caches are flushed after every write request to the
>>> +# export before completion is signalled. (since: 5.2;
>>> +# default: false)
>>> +#
>>> # Since: 4.2
>>> ##
>>> { 'union': 'BlockExportOptions',
>>> - 'base': { 'type': 'BlockExportType' },
>>> + 'base': { 'type': 'BlockExportType',
>>> + '*writethrough': 'bool' },
>>> 'discriminator': 'type',
>>> 'data': {
>>> 'nbd': 'BlockExportOptionsNbd'
>>
>> Hm. I find it weird to have @writethrough in the base but @device in
>> the specialized class.
>>
>> I think everything that will be common to all block exports should be in
>> the base, and that probably includes a node-name. I’m aware that will
>> make things more tedious in the code, but perhaps it would be a nicer
>> interface in the end. Or is the real problem that that would create
>> problems in the storage daemon’s command line interface, because then
>> the specialized (legacy) NBD interface would no longer be compatible
>> with the new generalized block export interface?
>
> Indeed. I think patch 15 has what you're looking for.
Great. :)
Discussions where both participants have the same opinion from the start
are the best ones.
>> Anyway, @writable might be a similar story. A @read-only may make sense
>> in general, I think.
>
> Pulling @writable up is easier than a @read-only, but that's a naming
> detail.
Sure.
> In general I agree, but this part isn't addressed in this series yet.
> Part of the reason why this is an RFC was to find out if I should
> include things like this or if we'll do it when we add another export
> type or common functionality that needs the same option.
Sure, sure.
Meta: I personally don’t like RFC patches very much. RFC to me means
everything is fair game, and reviewers should be free to let their
thoughts wander and come up with perhaps wild ideas, just trying to
gauge what everyone thinks.
When I’m the submitter, I tend to get defensive then, because I’ve
invested time in writing the code already, so I tend to be biased
against fundamental changes. (Horrible personal trait. I’m working on it.)
As a reviewer, the code and thus some fleshed out design is there
already, so it’s difficult to break free from that and find completely
different solutions to the original problem.
(I kind of ventured in that direction for this patch, and it seems like
you immediately noticed that my response was different from usual and
pointed out the RFC status, perhaps to make me feel more comfortable in
questioning the fundamental design more. Which I noticed, hence this
wall of text.)
Perhaps I’m wrong. Perhaps it’s just myself (the points I’ve just
listed are definitely my own personal weaknesses), but I can’t help but
project and assume that others may feel similar, at least in part.
So I feel like RFCs that consist of patches tend to at least lock me in
to the solution that’s present. I find them difficult to handle, both
as a submitter and as a reviewer.
All in all, that means on either side I tend to handle patch RFCs as
“Standard series, just tests missing”. Not sure if that’s ideal. Or
maybe that’s exactly what patch RFCs are?
(Of course, it can and should be argued that even for standard series, I
shouldn’t be afraid of questioning the fundamental design still. But
that’s hard...)
But, well. The alternative is writing pure design RFCs, and then you
tend to get weeks of slow discussion, drawing everything out. Which
isn’t ideal either. Or is that just a baseless prejudice I have?
>> Basically, I think that the export code should be separate from the code
>> setting up the BlockBackend that should be exported, so all options
>> regarding that BB should be common; and those options are @node-name,
>> @writethrough, and @read-only. (And perhaps other things like
>> @resizable, too, even though that isn’t something to consider for NBD.)
>
> Do you mean that the BlockBackend should already be created by the
> generic block export layer?
It would certainly be nice, if it were feasible, don’t you think?
We don’t have to bend backwards for it, but maybe it would force us to
bring the natural separation of block device and export parameters to
the interface.
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-17 13:51 ` Max Reitz
@ 2020-08-17 14:32 ` Kevin Wolf
2020-08-17 15:35 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 14:32 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 7159 bytes --]
Am 17.08.2020 um 15:51 hat Max Reitz geschrieben:
> On 17.08.20 15:13, Kevin Wolf wrote:
> > Am 17.08.2020 um 14:56 hat Max Reitz geschrieben:
> >> On 13.08.20 18:29, Kevin Wolf wrote:
> >>> qemu-nbd allows use of writethrough cache modes, which mean that write
> >>> requests made through NBD will cause a flush before they complete.
> >>> Expose the same functionality in block-export-add.
> >>>
> >>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> >>> ---
> >>> qapi/block-export.json | 7 ++++++-
> >>> blockdev-nbd.c | 2 +-
> >>> 2 files changed, 7 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/qapi/block-export.json b/qapi/block-export.json
> >>> index 1fdc55c53a..4ce163411f 100644
> >>> --- a/qapi/block-export.json
> >>> +++ b/qapi/block-export.json
> >>> @@ -167,10 +167,15 @@
> >>> # Describes a block export, i.e. how single node should be exported on an
> >>> # external interface.
> >>> #
> >>> +# @writethrough: If true, caches are flushed after every write request to the
> >>> +# export before completion is signalled. (since: 5.2;
> >>> +# default: false)
> >>> +#
> >>> # Since: 4.2
> >>> ##
> >>> { 'union': 'BlockExportOptions',
> >>> - 'base': { 'type': 'BlockExportType' },
> >>> + 'base': { 'type': 'BlockExportType',
> >>> + '*writethrough': 'bool' },
> >>> 'discriminator': 'type',
> >>> 'data': {
> >>> 'nbd': 'BlockExportOptionsNbd'
> >>
> >> Hm. I find it weird to have @writethrough in the base but @device in
> >> the specialized class.
> >>
> >> I think everything that will be common to all block exports should be in
> >> the base, and that probably includes a node-name. I’m aware that will
> >> make things more tedious in the code, but perhaps it would be a nicer
> >> interface in the end. Or is the real problem that that would create
> >> problems in the storage daemon’s command line interface, because then
> >> the specialized (legacy) NBD interface would no longer be compatible
> >> with the new generalized block export interface?
> >
> > Indeed. I think patch 15 has what you're looking for.
>
> Great. :)
>
> Discussions where both participants have the same opinion from the
> start are the best ones.
Makes things a lot easier.
Maybe I should try to move patch 15 earlier. The series is mostly just
in the order that I wrote things, but there were also a few nasty
dependencies in the part the generalises things from NBD to BlockExport.
So I'm not sure if this is a patch that can be moved.
> >> Anyway, @writable might be a similar story. A @read-only may make sense
> >> in general, I think.
> >
> > Pulling @writable up is easier than a @read-only, but that's a naming
> > detail.
>
> Sure.
>
> > In general I agree, but this part isn't addressed in this series yet.
> > Part of the reason why this is an RFC was to find out if I should
> > include things like this or if we'll do it when we add another export
> > type or common functionality that needs the same option.
>
> Sure, sure.
So should I or not? :-)
> Meta: I personally don’t like RFC patches very much. RFC to me means
> everything is fair game, and reviewers should be free to let their
> thoughts wander and come up with perhaps wild ideas, just trying to
> gauge what everyone thinks.
>
> When I’m the submitter, I tend to get defensive then, because I’ve
> invested time in writing the code already, so I tend to be biased
> against fundamental changes. (Horrible personal trait. I’m working
> on it.)
This makes sense. Nobody likes having to rewrite their RFC series.
But there is one thing I dread even more: Polishing the RFC series for
another week until I can send it out as non-RFC and _then_ having to
rewrite it.
> As a reviewer, the code and thus some fleshed out design is there
> already, so it’s difficult to break free from that and find completely
> different solutions to the original problem.
> (I kind of ventured in that direction for this patch, and it seems like
> you immediately noticed that my response was different from usual and
> pointed out the RFC status, perhaps to make me feel more comfortable in
> questioning the fundamental design more. Which I noticed, hence this
> wall of text.)
Basically just telling you that I was already interested in your input
for this point specifically when I sent the series.
> Perhaps I’m wrong. Perhaps it’s just myself (the points I’ve just
> listed are definitely my own personal weaknesses), but I can’t help but
> project and assume that others may feel similar, at least in part.
> So I feel like RFCs that consist of patches tend to at least lock me in
> to the solution that’s present. I find them difficult to handle, both
> as a submitter and as a reviewer.
>
> All in all, that means on either side I tend to handle patch RFCs as
> “Standard series, just tests missing”. Not sure if that’s ideal. Or
> maybe that’s exactly what patch RFCs are?
>
> (Of course, it can and should be argued that even for standard series, I
> shouldn’t be afraid of questioning the fundamental design still. But
> that’s hard...)
I usually send RFC patches when I know that I wouldn't consider them
mergable yet, but I don't want to invest the time to polish them before
I know that other people agree with the approach and the time won't be
wasted.
> But, well. The alternative is writing pure design RFCs, and then you
> tend to get weeks of slow discussion, drawing everything out. Which
> isn’t ideal either. Or is that just a baseless prejudice I have?
In many cases (and I think this is one of them in large parts), I only
really learn what the series will look like when I write it.
I could have sent a design RFC for the QAPI part, but I didn't expect
this to be contentious because it's just the normal add/del/query thing
that exists for pretty much everything else, too.
> >> Basically, I think that the export code should be separate from the code
> >> setting up the BlockBackend that should be exported, so all options
> >> regarding that BB should be common; and those options are @node-name,
> >> @writethrough, and @read-only. (And perhaps other things like
> >> @resizable, too, even though that isn’t something to consider for NBD.)
> >
> > Do you mean that the BlockBackend should already be created by the
> > generic block export layer?
>
> It would certainly be nice, if it were feasible, don’t you think?
>
> We don’t have to bend backwards for it, but maybe it would force us to
> bring the natural separation of block device and export parameters to
> the interface.
I can try. I seem to remember that you had a reason not to do this the
last time we discussed generalised exports, but I'm not sure what it
was.
The obvious one could be that the block export layer doesn't know which
permissions are needed. But it can always start with minimal permissions
and let the driver do a blk_set_perm() if it needs more.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-17 14:32 ` Kevin Wolf
@ 2020-08-17 15:35 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 15:35 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 8280 bytes --]
On 17.08.20 16:32, Kevin Wolf wrote:
> Am 17.08.2020 um 15:51 hat Max Reitz geschrieben:
>> On 17.08.20 15:13, Kevin Wolf wrote:
>>> Am 17.08.2020 um 14:56 hat Max Reitz geschrieben:
>>>> On 13.08.20 18:29, Kevin Wolf wrote:
>>>>> qemu-nbd allows use of writethrough cache modes, which mean that write
>>>>> requests made through NBD will cause a flush before they complete.
>>>>> Expose the same functionality in block-export-add.
>>>>>
>>>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>>>> ---
>>>>> qapi/block-export.json | 7 ++++++-
>>>>> blockdev-nbd.c | 2 +-
>>>>> 2 files changed, 7 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/qapi/block-export.json b/qapi/block-export.json
>>>>> index 1fdc55c53a..4ce163411f 100644
>>>>> --- a/qapi/block-export.json
>>>>> +++ b/qapi/block-export.json
>>>>> @@ -167,10 +167,15 @@
>>>>> # Describes a block export, i.e. how single node should be exported on an
>>>>> # external interface.
>>>>> #
>>>>> +# @writethrough: If true, caches are flushed after every write request to the
>>>>> +# export before completion is signalled. (since: 5.2;
>>>>> +# default: false)
>>>>> +#
>>>>> # Since: 4.2
>>>>> ##
>>>>> { 'union': 'BlockExportOptions',
>>>>> - 'base': { 'type': 'BlockExportType' },
>>>>> + 'base': { 'type': 'BlockExportType',
>>>>> + '*writethrough': 'bool' },
>>>>> 'discriminator': 'type',
>>>>> 'data': {
>>>>> 'nbd': 'BlockExportOptionsNbd'
>>>>
>>>> Hm. I find it weird to have @writethrough in the base but @device in
>>>> the specialized class.
>>>>
>>>> I think everything that will be common to all block exports should be in
>>>> the base, and that probably includes a node-name. I’m aware that will
>>>> make things more tedious in the code, but perhaps it would be a nicer
>>>> interface in the end. Or is the real problem that that would create
>>>> problems in the storage daemon’s command line interface, because then
>>>> the specialized (legacy) NBD interface would no longer be compatible
>>>> with the new generalized block export interface?
>>>
>>> Indeed. I think patch 15 has what you're looking for.
>>
>> Great. :)
>>
>> Discussions where both participants have the same opinion from the
>> start are the best ones.
>
> Makes things a lot easier.
>
> Maybe I should try to move patch 15 earlier. The series is mostly just
> in the order that I wrote things, but there were also a few nasty
> dependencies in the part the generalises things from NBD to BlockExport.
> So I'm not sure if this is a patch that can be moved.
>
>>>> Anyway, @writable might be a similar story. A @read-only may make sense
>>>> in general, I think.
>>>
>>> Pulling @writable up is easier than a @read-only, but that's a naming
>>> detail.
>>
>> Sure.
>>
>>> In general I agree, but this part isn't addressed in this series yet.
>>> Part of the reason why this is an RFC was to find out if I should
>>> include things like this or if we'll do it when we add another export
>>> type or common functionality that needs the same option.
>>
>> Sure, sure.
>
> So should I or not? :-)
Can we delay it until after this series? I.e., as long as it retains
the name “writable”, would pulling it up into BlockExportOptions a
compatible change?
If so, then I suppose we could do it afterwards. But I think it does
make the most sense to “just” do it as part of this series.
>> Meta: I personally don’t like RFC patches very much. RFC to me means
>> everything is fair game, and reviewers should be free to let their
>> thoughts wander and come up with perhaps wild ideas, just trying to
>> gauge what everyone thinks.
>>
>> When I’m the submitter, I tend to get defensive then, because I’ve
>> invested time in writing the code already, so I tend to be biased
>> against fundamental changes. (Horrible personal trait. I’m working
>> on it.)
>
> This makes sense. Nobody likes having to rewrite their RFC series.
>
> But there is one thing I dread even more: Polishing the RFC series for
> another week until I can send it out as non-RFC and _then_ having to
> rewrite it.
Yes. Especially bad with tests.
>> As a reviewer, the code and thus some fleshed out design is there
>> already, so it’s difficult to break free from that and find completely
>> different solutions to the original problem.
>> (I kind of ventured in that direction for this patch, and it seems like
>> you immediately noticed that my response was different from usual and
>> pointed out the RFC status, perhaps to make me feel more comfortable in
>> questioning the fundamental design more. Which I noticed, hence this
>> wall of text.)
>
> Basically just telling you that I was already interested in your input
> for this point specifically when I sent the series.
OK :)
>> Perhaps I’m wrong. Perhaps it’s just myself (the points I’ve just
>> listed are definitely my own personal weaknesses), but I can’t help but
>> project and assume that others may feel similar, at least in part.
>> So I feel like RFCs that consist of patches tend to at least lock me in
>> to the solution that’s present. I find them difficult to handle, both
>> as a submitter and as a reviewer.
>>
>> All in all, that means on either side I tend to handle patch RFCs as
>> “Standard series, just tests missing”. Not sure if that’s ideal. Or
>> maybe that’s exactly what patch RFCs are?
>>
>> (Of course, it can and should be argued that even for standard series, I
>> shouldn’t be afraid of questioning the fundamental design still. But
>> that’s hard...)
>
> I usually send RFC patches when I know that I wouldn't consider them
> mergable yet, but I don't want to invest the time to polish them before
> I know that other people agree with the approach and the time won't be
> wasted.
>
>> But, well. The alternative is writing pure design RFCs, and then you
>> tend to get weeks of slow discussion, drawing everything out. Which
>> isn’t ideal either. Or is that just a baseless prejudice I have?
>
> In many cases (and I think this is one of them in large parts), I only
> really learn what the series will look like when I write it.
That’s true. With a pure design RFC, it’s often difficult to know even
the scope of the design until you’ve begun to write code. So there’s a
danger of just writing a bunch of uncontroversial basic design stuff
because one has no idea of what may actually become problematic and
questionable. :/
> I could have sent a design RFC for the QAPI part, but I didn't expect
> this to be contentious because it's just the normal add/del/query thing
> that exists for pretty much everything else, too.
Yeah, the functions themselves are clear.
Hm. Perhaps software engineering just is actually difficult, and
there’s no way around it.
>>>> Basically, I think that the export code should be separate from the code
>>>> setting up the BlockBackend that should be exported, so all options
>>>> regarding that BB should be common; and those options are @node-name,
>>>> @writethrough, and @read-only. (And perhaps other things like
>>>> @resizable, too, even though that isn’t something to consider for NBD.)
>>>
>>> Do you mean that the BlockBackend should already be created by the
>>> generic block export layer?
>>
>> It would certainly be nice, if it were feasible, don’t you think?
>>
>> We don’t have to bend backwards for it, but maybe it would force us to
>> bring the natural separation of block device and export parameters to
>> the interface.
>
> I can try. I seem to remember that you had a reason not to do this the
> last time we discussed generalised exports, but I'm not sure what it
> was.
>
> The obvious one could be that the block export layer doesn't know which
> permissions are needed. But it can always start with minimal permissions
> and let the driver do a blk_set_perm() if it needs more.
Trying sounds good. Since there shouldn’t be consequences for the QMP
interface, we™ can always try again later (i.e., when adding more export
types).
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-17 12:56 ` Max Reitz
2020-08-17 13:13 ` Kevin Wolf
@ 2020-08-19 20:05 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:05 UTC (permalink / raw)
To: Max Reitz, Kevin Wolf, qemu-block; +Cc: qemu-devel
On 8/17/20 7:56 AM, Max Reitz wrote:
> On 13.08.20 18:29, Kevin Wolf wrote:
>> qemu-nbd allows use of writethrough cache modes, which mean that write
>> requests made through NBD will cause a flush before they complete.
>> Expose the same functionality in block-export-add.
>>
>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>> ---
>> +++ b/qapi/block-export.json
>> @@ -167,10 +167,15 @@
>> # Describes a block export, i.e. how single node should be exported on an
>> # external interface.
>> #
>> +# @writethrough: If true, caches are flushed after every write request to the
>> +# export before completion is signalled. (since: 5.2;
>> +# default: false)
>> +#
>> # Since: 4.2
>> ##
>> { 'union': 'BlockExportOptions',
>> - 'base': { 'type': 'BlockExportType' },
>> + 'base': { 'type': 'BlockExportType',
>> + '*writethrough': 'bool' },
>> 'discriminator': 'type',
>> 'data': {
>> 'nbd': 'BlockExportOptionsNbd'
>
> Hm. I find it weird to have @writethrough in the base but @device in
> the specialized class.
>
> I think everything that will be common to all block exports should be in
> the base, and that probably includes a node-name. I’m aware that will
> make things more tedious in the code, but perhaps it would be a nicer
> interface in the end. Or is the real problem that that would create
> problems in the storage daemon’s command line interface, because then
> the specialized (legacy) NBD interface would no longer be compatible
> with the new generalized block export interface?
>
> Anyway, @writable might be a similar story. A @read-only may make sense
> in general, I think.
And maybe even auto-read-only. As for @writable vs. @read-only, that's
a choice of spelling, but we don't want both; there's also the question
of which default is saner (having to opt-in to allowing writes is more
verbose than defaulting to allowing writes when possible, but arguably
saner as it is less risk of unintended writes when you forgot to specify
the option; @auto-read-only can help in choosing nicer defaults).
>
> Basically, I think that the export code should be separate from the code
> setting up the BlockBackend that should be exported, so all options
> regarding that BB should be common; and those options are @node-name,
> @writethrough, and @read-only. (And perhaps other things like
> @resizable, too, even though that isn’t something to consider for NBD.)
NBD isn't resizable yet, but extending the protocol to let it become so
is on my TODO list.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 09/22] nbd: Add writethrough to block-export-add
2020-08-13 16:29 ` [RFC PATCH 09/22] nbd: Add writethrough to block-export-add Kevin Wolf
2020-08-17 12:56 ` Max Reitz
@ 2020-08-19 20:13 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> qemu-nbd allows use of writethrough cache modes, which mean that write
> requests made through NBD will cause a flush before they complete.
> Expose the same functionality in block-export-add.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 7 ++++++-
> blockdev-nbd.c | 2 +-
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> +++ b/blockdev-nbd.c
> @@ -218,7 +218,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
>
> exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
> !arg->writable, !arg->writable,
> - NULL, false, errp);
> + NULL, exp_args->writethrough, errp);
It would someday be nice to get rid of exp_args->has_writethrough in
QAPI generated code, but that's independent of this series. Meanwhile,
you are safe in relying on writethrough being false when
has_writethrough is false.
This change makes sense to me interface-wise. QAPI-wise, should we try
harder to make writethrough settable only for writable exports (and an
error for read-only exports)? I'm not sure what QAPI contortions would
have to look like to make that enforced by the QMP parser; but it's also
not the end of the world if we just always permit the optional field and
then apply a post-parse semantic check.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 10/22] nbd: Remove NBDExport.close callback
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (8 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 09/22] nbd: Add writethrough to block-export-add Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 14:02 ` Max Reitz
2020-08-19 20:17 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export Kevin Wolf
` (11 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
The export close callback is unused by the built-in NBD server. qemu-nbd
uses it only during shutdown to wait for the unrefed export to actually
go away. It can just use nbd_export_close_all() instead and do without
the callback.
This removes the close callback from nbd_export_new() and makes both
callers of it more similar.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/nbd.h | 3 +--
blockdev-nbd.c | 2 +-
nbd/server.c | 9 +--------
qemu-nbd.c | 14 ++++----------
4 files changed, 7 insertions(+), 21 deletions(-)
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 6fc1f05ef4..50e1a46075 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -332,8 +332,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp);
NBDExport *nbd_export_new(BlockDriverState *bs,
const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
- void (*close)(NBDExport *), bool writethrough,
- Error **errp);
+ bool writethrough, Error **errp);
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 17417c1b6b..d5b084acc2 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -218,7 +218,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
!arg->writable, !arg->writable,
- NULL, exp_args->writethrough, errp);
+ exp_args->writethrough, errp);
if (!exp) {
goto out;
}
diff --git a/nbd/server.c b/nbd/server.c
index 0b84fd30e2..eadc5b9804 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -84,7 +84,6 @@ struct NBDRequestData {
struct NBDExport {
BlockExport common;
int refcount;
- void (*close)(NBDExport *exp);
BlockBackend *blk;
char *name;
@@ -1520,8 +1519,7 @@ void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
NBDExport *nbd_export_new(BlockDriverState *bs,
const char *name, const char *desc,
const char *bitmap, bool readonly, bool shared,
- void (*close)(NBDExport *), bool writethrough,
- Error **errp)
+ bool writethrough, Error **errp)
{
AioContext *ctx;
BlockBackend *blk;
@@ -1625,7 +1623,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
assert(strlen(exp->export_bitmap_context) < NBD_MAX_STRING_SIZE);
}
- exp->close = close;
exp->ctx = ctx;
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
@@ -1723,10 +1720,6 @@ void nbd_export_put(NBDExport *exp)
assert(exp->name == NULL);
assert(exp->description == NULL);
- if (exp->close) {
- exp->close(exp);
- }
-
if (exp->blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
diff --git a/qemu-nbd.c b/qemu-nbd.c
index e348d5d6d8..48aa8a9d46 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -70,7 +70,7 @@ static int verbose;
static char *srcpath;
static SocketAddress *saddr;
static int persistent = 0;
-static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
+static enum { RUNNING, TERMINATE, TERMINATED } state;
static int shared = 1;
static int nb_fds;
static QIONetListener *server;
@@ -331,12 +331,6 @@ static int nbd_can_accept(void)
return state == RUNNING && nb_fds < shared;
}
-static void nbd_export_closed(NBDExport *export)
-{
- assert(state == TERMINATING);
- state = TERMINATED;
-}
-
static void nbd_update_server_watch(void);
static void nbd_client_closed(NBDClient *client, bool negotiated)
@@ -1058,7 +1052,7 @@ int main(int argc, char **argv)
export = nbd_export_new(bs, export_name,
export_description, bitmap, readonly, shared > 1,
- nbd_export_closed, writethrough, &error_fatal);
+ writethrough, &error_fatal);
if (device) {
#if HAVE_NBD_DEVICE
@@ -1098,10 +1092,10 @@ int main(int argc, char **argv)
do {
main_loop_wait(false);
if (state == TERMINATE) {
- state = TERMINATING;
- nbd_export_close(export);
nbd_export_put(export);
+ nbd_export_close_all();
export = NULL;
+ state = TERMINATED;
}
} while (state != TERMINATED);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 10/22] nbd: Remove NBDExport.close callback
2020-08-13 16:29 ` [RFC PATCH 10/22] nbd: Remove NBDExport.close callback Kevin Wolf
@ 2020-08-17 14:02 ` Max Reitz
2020-08-19 20:17 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:02 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 696 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> The export close callback is unused by the built-in NBD server. qemu-nbd
> uses it only during shutdown to wait for the unrefed export to actually
> go away. It can just use nbd_export_close_all() instead and do without
> the callback.
>
> This removes the close callback from nbd_export_new() and makes both
> callers of it more similar.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/nbd.h | 3 +--
> blockdev-nbd.c | 2 +-
> nbd/server.c | 9 +--------
> qemu-nbd.c | 14 ++++----------
> 4 files changed, 7 insertions(+), 21 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 10/22] nbd: Remove NBDExport.close callback
2020-08-13 16:29 ` [RFC PATCH 10/22] nbd: Remove NBDExport.close callback Kevin Wolf
2020-08-17 14:02 ` Max Reitz
@ 2020-08-19 20:17 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:17 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> The export close callback is unused by the built-in NBD server. qemu-nbd
> uses it only during shutdown to wait for the unrefed export to actually
> go away. It can just use nbd_export_close_all() instead and do without
> the callback.
>
> This removes the close callback from nbd_export_new() and makes both
> callers of it more similar.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (9 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 10/22] nbd: Remove NBDExport.close callback Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 14:27 ` Max Reitz
2020-08-19 20:35 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 12/22] nbd/server: Simplify export shutdown Kevin Wolf
` (10 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
With this change, NBD exports are only created through the BlockExport
interface any more. This allows us finally to move things from the NBD
layer to the BlockExport layer if they make sense for other export
types, too.
blk_exp_add() returns only a weak reference, so the explicit
nbd_export_put() goes away.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 2 ++
include/block/nbd.h | 1 +
block/export/export.c | 2 +-
blockdev-nbd.c | 8 +++++++-
qemu-nbd.c | 28 ++++++++++++++++++++++------
5 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index b1d7325403..5424bdc85d 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -29,4 +29,6 @@ struct BlockExport {
extern const BlockExportDriver blk_exp_nbd;
+BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
+
#endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 50e1a46075..23030db3f1 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -350,6 +350,7 @@ void nbd_client_new(QIOChannelSocket *sioc,
void nbd_client_get(NBDClient *client);
void nbd_client_put(NBDClient *client);
+void nbd_server_is_qemu_nbd(bool value);
void nbd_server_start(SocketAddress *addr, const char *tls_creds,
const char *tls_authz, uint32_t max_connections,
Error **errp);
diff --git a/block/export/export.c b/block/export/export.c
index 2d5f92861c..12672228c7 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -36,7 +36,7 @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
return NULL;
}
-static BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
+BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
{
const BlockExportDriver *drv;
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index d5b084acc2..8dd127af52 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -28,9 +28,15 @@ typedef struct NBDServerData {
} NBDServerData;
static NBDServerData *nbd_server;
+static bool is_qemu_nbd;
static void nbd_update_server_watch(NBDServerData *s);
+void nbd_server_is_qemu_nbd(bool value)
+{
+ is_qemu_nbd = value;
+}
+
static void nbd_blockdev_client_closed(NBDClient *client, bool ignored)
{
nbd_client_put(client);
@@ -176,7 +182,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
- if (!nbd_server) {
+ if (!nbd_server && !is_qemu_nbd) {
error_setg(errp, "NBD server not running");
return NULL;
}
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 48aa8a9d46..d967b8fcb9 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -65,7 +65,6 @@
#define MBR_SIZE 512
-static NBDExport *export;
static int verbose;
static char *srcpath;
static SocketAddress *saddr;
@@ -579,6 +578,7 @@ int main(int argc, char **argv)
int old_stderr = -1;
unsigned socket_activation;
const char *pid_file_name = NULL;
+ BlockExportOptions *export_opts;
/* The client thread uses SIGTERM to interrupt the server. A signal
* handler ensures that "qemu-nbd -v -c" exits with a nice status code.
@@ -1050,9 +1050,27 @@ int main(int argc, char **argv)
bs->detect_zeroes = detect_zeroes;
- export = nbd_export_new(bs, export_name,
- export_description, bitmap, readonly, shared > 1,
- writethrough, &error_fatal);
+ nbd_server_is_qemu_nbd(true);
+
+ export_opts = g_new(BlockExportOptions, 1);
+ *export_opts = (BlockExportOptions) {
+ .type = BLOCK_EXPORT_TYPE_NBD,
+ .has_writethrough = true,
+ .writethrough = writethrough,
+ .u.nbd = {
+ .device = g_strdup(bdrv_get_node_name(bs)),
+ .has_name = true,
+ .name = g_strdup(export_name),
+ .has_description = !!export_description,
+ .description = g_strdup(export_description),
+ .has_writable = true,
+ .writable = !readonly,
+ .has_bitmap = !!bitmap,
+ .bitmap = g_strdup(bitmap),
+ },
+ };
+ blk_exp_add(export_opts, &error_fatal);
+ qapi_free_BlockExportOptions(export_opts);
if (device) {
#if HAVE_NBD_DEVICE
@@ -1092,9 +1110,7 @@ int main(int argc, char **argv)
do {
main_loop_wait(false);
if (state == TERMINATE) {
- nbd_export_put(export);
nbd_export_close_all();
- export = NULL;
state = TERMINATED;
}
} while (state != TERMINATED);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export
2020-08-13 16:29 ` [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export Kevin Wolf
@ 2020-08-17 14:27 ` Max Reitz
2020-08-17 14:38 ` Max Reitz
2020-08-17 15:01 ` Kevin Wolf
2020-08-19 20:35 ` Eric Blake
1 sibling, 2 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:27 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 2901 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> With this change, NBD exports are only created through the BlockExport
> interface any more. This allows us finally to move things from the NBD
> layer to the BlockExport layer if they make sense for other export
> types, too.
I see.
> blk_exp_add() returns only a weak reference, so the explicit
> nbd_export_put() goes away.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 2 ++
> include/block/nbd.h | 1 +
> block/export/export.c | 2 +-
> blockdev-nbd.c | 8 +++++++-
> qemu-nbd.c | 28 ++++++++++++++++++++++------
> 5 files changed, 33 insertions(+), 8 deletions(-)
[...]
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index d5b084acc2..8dd127af52 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
[...]
> @@ -176,7 +182,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
>
> assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
>
> - if (!nbd_server) {
> + if (!nbd_server && !is_qemu_nbd) {
(This begs the question of how difficult it would be to let qemu-nbd use
QMP’s nbd-server-start, but I will not ask it, for I fear the answer.)
> error_setg(errp, "NBD server not running");
> return NULL;
> }
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index 48aa8a9d46..d967b8fcb9 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
[...]
> @@ -1050,9 +1050,27 @@ int main(int argc, char **argv)
>
> bs->detect_zeroes = detect_zeroes;
>
> - export = nbd_export_new(bs, export_name,
> - export_description, bitmap, readonly, shared > 1,
> - writethrough, &error_fatal);
> + nbd_server_is_qemu_nbd(true);
> +
> + export_opts = g_new(BlockExportOptions, 1);
> + *export_opts = (BlockExportOptions) {
> + .type = BLOCK_EXPORT_TYPE_NBD,
> + .has_writethrough = true,
> + .writethrough = writethrough,
> + .u.nbd = {
> + .device = g_strdup(bdrv_get_node_name(bs)),
> + .has_name = true,
> + .name = g_strdup(export_name),
> + .has_description = !!export_description,
> + .description = g_strdup(export_description),
> + .has_writable = true,
> + .writable = !readonly,
> + .has_bitmap = !!bitmap,
> + .bitmap = g_strdup(bitmap),
> + },
> + };
> + blk_exp_add(export_opts, &error_fatal);
Why not use the already-global qmp_block_export_add(), if we don’t need
the return value here? (Will we require it at some point?)
Max
> + qapi_free_BlockExportOptions(export_opts);
>
> if (device) {
> #if HAVE_NBD_DEVICE
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export
2020-08-17 14:27 ` Max Reitz
@ 2020-08-17 14:38 ` Max Reitz
2020-08-17 15:01 ` Kevin Wolf
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:38 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 3115 bytes --]
On 17.08.20 16:27, Max Reitz wrote:
> On 13.08.20 18:29, Kevin Wolf wrote:
>> With this change, NBD exports are only created through the BlockExport
>> interface any more. This allows us finally to move things from the NBD
>> layer to the BlockExport layer if they make sense for other export
>> types, too.
>
> I see.
>
>> blk_exp_add() returns only a weak reference, so the explicit
>> nbd_export_put() goes away.
>>
>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>> ---
>> include/block/export.h | 2 ++
>> include/block/nbd.h | 1 +
>> block/export/export.c | 2 +-
>> blockdev-nbd.c | 8 +++++++-
>> qemu-nbd.c | 28 ++++++++++++++++++++++------
>> 5 files changed, 33 insertions(+), 8 deletions(-)
>
> [...]
>
>> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
>> index d5b084acc2..8dd127af52 100644
>> --- a/blockdev-nbd.c
>> +++ b/blockdev-nbd.c
>
> [...]
>
>> @@ -176,7 +182,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
>>
>> assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
>>
>> - if (!nbd_server) {
>> + if (!nbd_server && !is_qemu_nbd) {
>
> (This begs the question of how difficult it would be to let qemu-nbd use
> QMP’s nbd-server-start, but I will not ask it, for I fear the answer.)
>
>> error_setg(errp, "NBD server not running");
>> return NULL;
>> }
>> diff --git a/qemu-nbd.c b/qemu-nbd.c
>> index 48aa8a9d46..d967b8fcb9 100644
>> --- a/qemu-nbd.c
>> +++ b/qemu-nbd.c
>
> [...]
>
>> @@ -1050,9 +1050,27 @@ int main(int argc, char **argv)
>>
>> bs->detect_zeroes = detect_zeroes;
>>
>> - export = nbd_export_new(bs, export_name,
>> - export_description, bitmap, readonly, shared > 1,
>> - writethrough, &error_fatal);
>> + nbd_server_is_qemu_nbd(true);
>> +
>> + export_opts = g_new(BlockExportOptions, 1);
>> + *export_opts = (BlockExportOptions) {
>> + .type = BLOCK_EXPORT_TYPE_NBD,
>> + .has_writethrough = true,
>> + .writethrough = writethrough,
>> + .u.nbd = {
>> + .device = g_strdup(bdrv_get_node_name(bs)),
>> + .has_name = true,
>> + .name = g_strdup(export_name),
>> + .has_description = !!export_description,
>> + .description = g_strdup(export_description),
>> + .has_writable = true,
>> + .writable = !readonly,
>> + .has_bitmap = !!bitmap,
>> + .bitmap = g_strdup(bitmap),
>> + },
>> + };
>> + blk_exp_add(export_opts, &error_fatal);
>
> Why not use the already-global qmp_block_export_add(), if we don’t need
> the return value here? (Will we require it at some point?)
In the context of patch 13, which adds more blk_exp_* functions, it
makes sense to make blk_exp_add() global, and then to use it here. So:
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export
2020-08-17 14:27 ` Max Reitz
2020-08-17 14:38 ` Max Reitz
@ 2020-08-17 15:01 ` Kevin Wolf
1 sibling, 0 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 15:01 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 3414 bytes --]
Am 17.08.2020 um 16:27 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > With this change, NBD exports are only created through the BlockExport
> > interface any more. This allows us finally to move things from the NBD
> > layer to the BlockExport layer if they make sense for other export
> > types, too.
>
> I see.
>
> > blk_exp_add() returns only a weak reference, so the explicit
> > nbd_export_put() goes away.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > include/block/export.h | 2 ++
> > include/block/nbd.h | 1 +
> > block/export/export.c | 2 +-
> > blockdev-nbd.c | 8 +++++++-
> > qemu-nbd.c | 28 ++++++++++++++++++++++------
> > 5 files changed, 33 insertions(+), 8 deletions(-)
>
> [...]
>
> > diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> > index d5b084acc2..8dd127af52 100644
> > --- a/blockdev-nbd.c
> > +++ b/blockdev-nbd.c
>
> [...]
>
> > @@ -176,7 +182,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
> >
> > assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
> >
> > - if (!nbd_server) {
> > + if (!nbd_server && !is_qemu_nbd) {
>
> (This begs the question of how difficult it would be to let qemu-nbd use
> QMP’s nbd-server-start, but I will not ask it, for I fear the answer.)
(It would probably include something along the lines of "patches
welcome". (I initially wanted to do this, but came to the conclusion
that it wasn't for this series when I noticed the socket activation
code and discussed with danpb on IRC how to integrate it in
SocketAddress.))
> > error_setg(errp, "NBD server not running");
> > return NULL;
> > }
> > diff --git a/qemu-nbd.c b/qemu-nbd.c
> > index 48aa8a9d46..d967b8fcb9 100644
> > --- a/qemu-nbd.c
> > +++ b/qemu-nbd.c
>
> [...]
>
> > @@ -1050,9 +1050,27 @@ int main(int argc, char **argv)
> >
> > bs->detect_zeroes = detect_zeroes;
> >
> > - export = nbd_export_new(bs, export_name,
> > - export_description, bitmap, readonly, shared > 1,
> > - writethrough, &error_fatal);
> > + nbd_server_is_qemu_nbd(true);
> > +
> > + export_opts = g_new(BlockExportOptions, 1);
> > + *export_opts = (BlockExportOptions) {
> > + .type = BLOCK_EXPORT_TYPE_NBD,
> > + .has_writethrough = true,
> > + .writethrough = writethrough,
> > + .u.nbd = {
> > + .device = g_strdup(bdrv_get_node_name(bs)),
> > + .has_name = true,
> > + .name = g_strdup(export_name),
> > + .has_description = !!export_description,
> > + .description = g_strdup(export_description),
> > + .has_writable = true,
> > + .writable = !readonly,
> > + .has_bitmap = !!bitmap,
> > + .bitmap = g_strdup(bitmap),
> > + },
> > + };
> > + blk_exp_add(export_opts, &error_fatal);
>
> Why not use the already-global qmp_block_export_add(), if we don’t need
> the return value here? (Will we require it at some point?)
I can do that. I needed the return value originally, but after some
reshuffling of the series it magically disappeared.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export
2020-08-13 16:29 ` [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export Kevin Wolf
2020-08-17 14:27 ` Max Reitz
@ 2020-08-19 20:35 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:35 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> With this change, NBD exports are only created through the BlockExport
> interface any more. This allows us finally to move things from the NBD
s/are only/are now only/; s/any more //
> layer to the BlockExport layer if they make sense for other export
> types, too.
>
> blk_exp_add() returns only a weak reference, so the explicit
> nbd_export_put() goes away.
Feel free to rename get/put to ref/unref in your series if that makes
life any easier.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> @@ -1050,9 +1050,27 @@ int main(int argc, char **argv)
>
> bs->detect_zeroes = detect_zeroes;
>
> - export = nbd_export_new(bs, export_name,
> - export_description, bitmap, readonly, shared > 1,
> - writethrough, &error_fatal);
> + nbd_server_is_qemu_nbd(true);
Feels a bit like a backdoor hack, but gets the job done (and as you
said, we had quite an IRC conversation about what it would take to get
socket activation working, so leaving that in qemu-nbd for now is
reasonable for the first patch series).
> +
> + export_opts = g_new(BlockExportOptions, 1);
> + *export_opts = (BlockExportOptions) {
> + .type = BLOCK_EXPORT_TYPE_NBD,
> + .has_writethrough = true,
> + .writethrough = writethrough,
> + .u.nbd = {
> + .device = g_strdup(bdrv_get_node_name(bs)),
> + .has_name = true,
> + .name = g_strdup(export_name),
> + .has_description = !!export_description,
> + .description = g_strdup(export_description),
> + .has_writable = true,
> + .writable = !readonly,
> + .has_bitmap = !!bitmap,
> + .bitmap = g_strdup(bitmap),
> + },
> + };
> + blk_exp_add(export_opts, &error_fatal);
> + qapi_free_BlockExportOptions(export_opts);
Looks sane.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 12/22] nbd/server: Simplify export shutdown
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (10 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 11/22] qemu-nbd: Use blk_exp_add() to create the export Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 14:32 ` Max Reitz
2020-08-19 20:45 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport Kevin Wolf
` (9 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Closing export is somewhat convoluted because nbd_export_close() and
nbd_export_put() call each other and the ways they actually end up being
nested is not necessarily obvious.
However, it is not really necessary to call nbd_export_close() from
nbd_export_put() when putting the last reference because it only does
three things:
1. Close all clients. We're going to refcount 0 and all clients hold a
reference, so we know there is no active client any more.
2. Close the user reference (represented by exp->name being non-NULL).
The same argument applies: If the export were still named, we would
still have a reference.
3. Freeing exp->description. This is really cleanup work to be done when
the export is finally freed. There is no reason to already clear it
while clients are still in the process of shutting down.
So after moving the cleanup of exp->description, the code can be
simplified so that only nbd_export_close() calls nbd_export_put(), but
never the other way around.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
nbd/server.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index eadc5b9804..4c594e6558 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1678,8 +1678,6 @@ void nbd_export_close(NBDExport *exp)
QTAILQ_REMOVE(&exports, exp, next);
QTAILQ_INSERT_TAIL(&closed_exports, exp, next);
}
- g_free(exp->description);
- exp->description = NULL;
nbd_export_put(exp);
}
@@ -1706,19 +1704,12 @@ void nbd_export_get(NBDExport *exp)
void nbd_export_put(NBDExport *exp)
{
assert(exp->refcount > 0);
- if (exp->refcount == 1) {
- nbd_export_close(exp);
- }
-
- /* nbd_export_close() may theoretically reduce refcount to 0. It may happen
- * if someone calls nbd_export_put() on named export not through
- * nbd_export_set_name() when refcount is 1. So, let's assert that
- * it is > 0.
- */
- assert(exp->refcount > 0);
if (--exp->refcount == 0) {
assert(exp->name == NULL);
- assert(exp->description == NULL);
+ assert(QTAILQ_EMPTY(&exp->clients));
+
+ g_free(exp->description);
+ exp->description = NULL;
if (exp->blk) {
if (exp->eject_notifier_blk) {
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 12/22] nbd/server: Simplify export shutdown
2020-08-13 16:29 ` [RFC PATCH 12/22] nbd/server: Simplify export shutdown Kevin Wolf
@ 2020-08-17 14:32 ` Max Reitz
2020-08-19 20:45 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:32 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1320 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Closing export is somewhat convoluted because nbd_export_close() and
> nbd_export_put() call each other and the ways they actually end up being
> nested is not necessarily obvious.
>
> However, it is not really necessary to call nbd_export_close() from
> nbd_export_put() when putting the last reference because it only does
> three things:
>
> 1. Close all clients. We're going to refcount 0 and all clients hold a
> reference, so we know there is no active client any more.
>
> 2. Close the user reference (represented by exp->name being non-NULL).
> The same argument applies: If the export were still named, we would
> still have a reference.
>
> 3. Freeing exp->description. This is really cleanup work to be done when
> the export is finally freed. There is no reason to already clear it
> while clients are still in the process of shutting down.
Convincing.
> So after moving the cleanup of exp->description, the code can be
> simplified so that only nbd_export_close() calls nbd_export_put(), but
> never the other way around.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> nbd/server.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 12/22] nbd/server: Simplify export shutdown
2020-08-13 16:29 ` [RFC PATCH 12/22] nbd/server: Simplify export shutdown Kevin Wolf
2020-08-17 14:32 ` Max Reitz
@ 2020-08-19 20:45 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:45 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Closing export is somewhat convoluted because nbd_export_close() and
> nbd_export_put() call each other and the ways they actually end up being
> nested is not necessarily obvious.
You are in a maze of twisty little passages, all alike.
Yes, I've always hated that part of the code; thanks for tackling a cleanup.
>
> However, it is not really necessary to call nbd_export_close() from
> nbd_export_put() when putting the last reference because it only does
> three things:
>
> 1. Close all clients. We're going to refcount 0 and all clients hold a
> reference, so we know there is no active client any more.
>
> 2. Close the user reference (represented by exp->name being non-NULL).
> The same argument applies: If the export were still named, we would
> still have a reference.
>
> 3. Freeing exp->description. This is really cleanup work to be done when
> the export is finally freed. There is no reason to already clear it
> while clients are still in the process of shutting down.
>
> So after moving the cleanup of exp->description, the code can be
> simplified so that only nbd_export_close() calls nbd_export_put(), but
> never the other way around.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> nbd/server.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
>
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (11 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 12/22] nbd/server: Simplify export shutdown Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 14:49 ` Max Reitz
2020-08-19 20:58 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 14/22] block/export: Move AioContext " Kevin Wolf
` (8 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Having a refcount makes sense for all types of block exports. It is also
a prerequisite for keeping a list of all exports at the BlockExport
level.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 10 ++++++
include/block/nbd.h | 2 --
block/export/export.c | 14 ++++++++
blockdev-nbd.c | 2 +-
nbd/server.c | 72 +++++++++++++++++++-----------------------
5 files changed, 58 insertions(+), 42 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index 5424bdc85d..f44290a4a2 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -21,14 +21,24 @@ typedef struct BlockExport BlockExport;
typedef struct BlockExportDriver {
BlockExportType type;
BlockExport *(*create)(BlockExportOptions *, Error **);
+ void (*delete)(BlockExport *);
} BlockExportDriver;
struct BlockExport {
const BlockExportDriver *drv;
+
+ /*
+ * Reference count for this block export. This includes strong references
+ * both from the owner (qemu-nbd or the monitor) and clients connected to
+ * the export.
+ */
+ int refcount;
};
extern const BlockExportDriver blk_exp_nbd;
BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
+void blk_exp_ref(BlockExport *exp);
+void blk_exp_unref(BlockExport *exp);
#endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 23030db3f1..af8509ab70 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -336,8 +336,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
-void nbd_export_get(NBDExport *exp);
-void nbd_export_put(NBDExport *exp);
AioContext *nbd_export_aio_context(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);
diff --git a/block/export/export.c b/block/export/export.c
index 12672228c7..1d5de564c7 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -49,6 +49,20 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return drv->create(export, errp);
}
+void blk_exp_ref(BlockExport *exp)
+{
+ assert(exp->refcount > 0);
+ exp->refcount++;
+}
+
+void blk_exp_unref(BlockExport *exp)
+{
+ assert(exp->refcount > 0);
+ if (--exp->refcount == 0) {
+ exp->drv->delete(exp);
+ }
+}
+
void qmp_block_export_add(BlockExportOptions *export, Error **errp)
{
blk_exp_add(export, errp);
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 8dd127af52..a8b7b785e7 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -232,7 +232,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
/* The list of named exports has a strong reference to this export now and
* our only way of accessing it is through nbd_export_find(), so we can drop
* the strong reference that is @exp. */
- nbd_export_put(exp);
+ blk_exp_unref((BlockExport*) exp);
out:
aio_context_release(aio_context);
diff --git a/nbd/server.c b/nbd/server.c
index 4c594e6558..2bf30bb731 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -83,7 +83,6 @@ struct NBDRequestData {
struct NBDExport {
BlockExport common;
- int refcount;
BlockBackend *blk;
char *name;
@@ -499,7 +498,7 @@ static int nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes,
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
- nbd_export_get(client->exp);
+ blk_exp_ref(&client->exp->common);
nbd_check_meta_export(client);
return 0;
@@ -707,7 +706,7 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
client->exp = exp;
client->check_align = check_align;
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
- nbd_export_get(client->exp);
+ blk_exp_ref(&client->exp->common);
nbd_check_meta_export(client);
rc = 1;
}
@@ -1406,7 +1405,7 @@ void nbd_client_put(NBDClient *client)
g_free(client->tlsauthz);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
- nbd_export_put(client->exp);
+ blk_exp_unref(&client->exp->common);
}
g_free(client);
}
@@ -1537,7 +1536,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
exp = g_new0(NBDExport, 1);
exp->common = (BlockExport) {
- .drv = &blk_exp_nbd,
+ .drv = &blk_exp_nbd,
+ .refcount = 1,
};
/*
@@ -1566,7 +1566,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
blk_set_enable_write_cache(blk, !writethrough);
blk_set_allow_aio_context_change(blk, true);
- exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
exp->name = g_strdup(name);
@@ -1626,8 +1625,9 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
exp->ctx = ctx;
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
+ blk_exp_ref(&exp->common);
QTAILQ_INSERT_TAIL(&exports, exp, next);
- nbd_export_get(exp);
+
return exp;
fail:
@@ -1660,7 +1660,7 @@ void nbd_export_close(NBDExport *exp)
{
NBDClient *client, *next;
- nbd_export_get(exp);
+ blk_exp_ref(&exp->common);
/*
* TODO: Should we expand QMP NbdServerRemoveNode enum to allow a
* close mode that stops advertising the export to new clients but
@@ -1672,13 +1672,13 @@ void nbd_export_close(NBDExport *exp)
client_close(client, true);
}
if (exp->name) {
- nbd_export_put(exp);
+ blk_exp_unref(&exp->common);
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
QTAILQ_INSERT_TAIL(&closed_exports, exp, next);
}
- nbd_export_put(exp);
+ blk_exp_unref(&exp->common);
}
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
@@ -1695,47 +1695,41 @@ void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
error_append_hint(errp, "Use mode='hard' to force client disconnect\n");
}
-void nbd_export_get(NBDExport *exp)
-{
- assert(exp->refcount > 0);
- exp->refcount++;
-}
-
-void nbd_export_put(NBDExport *exp)
+static void nbd_export_delete(BlockExport *blk_exp)
{
- assert(exp->refcount > 0);
- if (--exp->refcount == 0) {
- assert(exp->name == NULL);
- assert(QTAILQ_EMPTY(&exp->clients));
+ NBDExport *exp = container_of(blk_exp, NBDExport, common);
- g_free(exp->description);
- exp->description = NULL;
+ assert(exp->name == NULL);
+ assert(QTAILQ_EMPTY(&exp->clients));
- if (exp->blk) {
- if (exp->eject_notifier_blk) {
- notifier_remove(&exp->eject_notifier);
- blk_unref(exp->eject_notifier_blk);
- }
- blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
- blk_aio_detach, exp);
- blk_unref(exp->blk);
- exp->blk = NULL;
- }
+ g_free(exp->description);
+ exp->description = NULL;
- if (exp->export_bitmap) {
- bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false);
- g_free(exp->export_bitmap_context);
+ if (exp->blk) {
+ if (exp->eject_notifier_blk) {
+ notifier_remove(&exp->eject_notifier);
+ blk_unref(exp->eject_notifier_blk);
}
+ blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
+ blk_aio_detach, exp);
+ blk_unref(exp->blk);
+ exp->blk = NULL;
+ }
- QTAILQ_REMOVE(&closed_exports, exp, next);
- g_free(exp);
- aio_wait_kick();
+ if (exp->export_bitmap) {
+ bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false);
+ g_free(exp->export_bitmap_context);
}
+
+ QTAILQ_REMOVE(&closed_exports, exp, next);
+ g_free(exp);
+ aio_wait_kick();
}
const BlockExportDriver blk_exp_nbd = {
.type = BLOCK_EXPORT_TYPE_NBD,
.create = nbd_export_create,
+ .delete = nbd_export_delete,
};
void nbd_export_close_all(void)
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport
2020-08-13 16:29 ` [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport Kevin Wolf
@ 2020-08-17 14:49 ` Max Reitz
2020-08-19 20:58 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:49 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1774 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Having a refcount makes sense for all types of block exports. It is also
> a prerequisite for keeping a list of all exports at the BlockExport
> level.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 10 ++++++
> include/block/nbd.h | 2 --
> block/export/export.c | 14 ++++++++
> blockdev-nbd.c | 2 +-
> nbd/server.c | 72 +++++++++++++++++++-----------------------
> 5 files changed, 58 insertions(+), 42 deletions(-)
[...]
> diff --git a/blockdev-nbd.c b/blockdev-nbd.c
> index 8dd127af52..a8b7b785e7 100644
> --- a/blockdev-nbd.c
> +++ b/blockdev-nbd.c
> @@ -232,7 +232,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
> /* The list of named exports has a strong reference to this export now and
> * our only way of accessing it is through nbd_export_find(), so we can drop
> * the strong reference that is @exp. */
> - nbd_export_put(exp);
> + blk_exp_unref((BlockExport*) exp);
:/
Less so because of the asterisk, but more so because of “another
instance of a cast because we can’t access a BlockExport’s fields.
> out:
> aio_context_release(aio_context);
> diff --git a/nbd/server.c b/nbd/server.c
> index 4c594e6558..2bf30bb731 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
[...]
> @@ -1537,7 +1536,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
>
> exp = g_new0(NBDExport, 1);
> exp->common = (BlockExport) {
> - .drv = &blk_exp_nbd,
> + .drv = &blk_exp_nbd,
> + .refcount = 1,
> };
This makes me wish... Ah, for patch 16, I see. :)
Reviewed-by: Max Reitz <mreitz@redhat.com>
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport
2020-08-13 16:29 ` [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport Kevin Wolf
2020-08-17 14:49 ` Max Reitz
@ 2020-08-19 20:58 ` Eric Blake
2020-08-20 14:15 ` Kevin Wolf
1 sibling, 1 reply; 90+ messages in thread
From: Eric Blake @ 2020-08-19 20:58 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Having a refcount makes sense for all types of block exports. It is also
> a prerequisite for keeping a list of all exports at the BlockExport
> level.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> +++ b/include/block/export.h
> @@ -21,14 +21,24 @@ typedef struct BlockExport BlockExport;
> typedef struct BlockExportDriver {
> BlockExportType type;
> BlockExport *(*create)(BlockExportOptions *, Error **);
> + void (*delete)(BlockExport *);
> } BlockExportDriver;
>
> struct BlockExport {
> const BlockExportDriver *drv;
> +
> + /*
> + * Reference count for this block export. This includes strong references
> + * both from the owner (qemu-nbd or the monitor) and clients connected to
> + * the export.
I guess 'the monitor' includes qemu-storage-daemon.
> + */
> + int refcount;
> };
>
> extern const BlockExportDriver blk_exp_nbd;
>
> BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
> +void blk_exp_ref(BlockExport *exp);
> +void blk_exp_unref(BlockExport *exp);
Yay, I think this naming is more consistent with the rest of qemu...
>
> #endif
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index 23030db3f1..af8509ab70 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -336,8 +336,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
> void nbd_export_close(NBDExport *exp);
> void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
> -void nbd_export_get(NBDExport *exp);
> -void nbd_export_put(NBDExport *exp);
...as opposed to this which is common in kernel but less so in this
project. No hard feelings from me :)
> +++ b/blockdev-nbd.c
> @@ -232,7 +232,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
> /* The list of named exports has a strong reference to this export now and
> * our only way of accessing it is through nbd_export_find(), so we can drop
> * the strong reference that is @exp. */
> - nbd_export_put(exp);
> + blk_exp_unref((BlockExport*) exp);
Even a helper function that converts NBDBlockExport* to BlockExport*
rather than a cast might be nicer, but then again, I see from Max's
review that this may be a temporary state of things.
(The QAPI contains such type-safe container casts, such as
qapi_DriveBackup_base(), if that helps...)
> @@ -1537,7 +1536,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
>
> exp = g_new0(NBDExport, 1);
> exp->common = (BlockExport) {
> - .drv = &blk_exp_nbd,
> + .drv = &blk_exp_nbd,
> + .refcount = 1,
I'm not sure whether trying to align the '=' is good, because the moment
you add a longer field name, every other line has to be touched. I'm
fine with just one space on both side of =, even if it is more ragged to
read. But you're the author, so you get to pick.
> @@ -1626,8 +1625,9 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> exp->ctx = ctx;
> blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
>
> + blk_exp_ref(&exp->common);
> QTAILQ_INSERT_TAIL(&exports, exp, next);
> - nbd_export_get(exp);
> +
Is there any consequence to this changed ordering in grabbing the
reference vs. updating the list?
Overall looks nice.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport
2020-08-19 20:58 ` Eric Blake
@ 2020-08-20 14:15 ` Kevin Wolf
0 siblings, 0 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-20 14:15 UTC (permalink / raw)
To: Eric Blake; +Cc: qemu-devel, qemu-block, mreitz
Am 19.08.2020 um 22:58 hat Eric Blake geschrieben:
> On 8/13/20 11:29 AM, Kevin Wolf wrote:
> > Having a refcount makes sense for all types of block exports. It is also
> > a prerequisite for keeping a list of all exports at the BlockExport
> > level.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
>
> > +++ b/include/block/export.h
> > @@ -21,14 +21,24 @@ typedef struct BlockExport BlockExport;
> > typedef struct BlockExportDriver {
> > BlockExportType type;
> > BlockExport *(*create)(BlockExportOptions *, Error **);
> > + void (*delete)(BlockExport *);
> > } BlockExportDriver;
> > struct BlockExport {
> > const BlockExportDriver *drv;
> > +
> > + /*
> > + * Reference count for this block export. This includes strong references
> > + * both from the owner (qemu-nbd or the monitor) and clients connected to
> > + * the export.
>
> I guess 'the monitor' includes qemu-storage-daemon.
Yes, qemu-storage-daemon has a QMP monitor, so I would count it there.
Even the --export command line option only calls the QMP command
internally.
> > + */
> > + int refcount;
> > };
> > extern const BlockExportDriver blk_exp_nbd;
> > BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
> > +void blk_exp_ref(BlockExport *exp);
> > +void blk_exp_unref(BlockExport *exp);
>
> Yay, I think this naming is more consistent with the rest of qemu...
>
> > #endif
> > diff --git a/include/block/nbd.h b/include/block/nbd.h
> > index 23030db3f1..af8509ab70 100644
> > --- a/include/block/nbd.h
> > +++ b/include/block/nbd.h
> > @@ -336,8 +336,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> > void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
> > void nbd_export_close(NBDExport *exp);
> > void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
> > -void nbd_export_get(NBDExport *exp);
> > -void nbd_export_put(NBDExport *exp);
>
> ...as opposed to this which is common in kernel but less so in this project.
> No hard feelings from me :)
>
> > +++ b/blockdev-nbd.c
> > @@ -232,7 +232,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
> > /* The list of named exports has a strong reference to this export now and
> > * our only way of accessing it is through nbd_export_find(), so we can drop
> > * the strong reference that is @exp. */
> > - nbd_export_put(exp);
> > + blk_exp_unref((BlockExport*) exp);
>
> Even a helper function that converts NBDBlockExport* to BlockExport* rather
> than a cast might be nicer, but then again, I see from Max's review that
> this may be a temporary state of things.
> (The QAPI contains such type-safe container casts, such as
> qapi_DriveBackup_base(), if that helps...)
Yes, this goes away before the end of the series.
> > @@ -1537,7 +1536,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> > exp = g_new0(NBDExport, 1);
> > exp->common = (BlockExport) {
> > - .drv = &blk_exp_nbd,
> > + .drv = &blk_exp_nbd,
> > + .refcount = 1,
>
> I'm not sure whether trying to align the '=' is good, because the moment you
> add a longer field name, every other line has to be touched. I'm fine with
> just one space on both side of =, even if it is more ragged to read. But
> you're the author, so you get to pick.
I generally prefer aligned '=' because the code is read much more often
than it is written or modified, so being friendly for readers is
important.
> > @@ -1626,8 +1625,9 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
> > exp->ctx = ctx;
> > blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
> > + blk_exp_ref(&exp->common);
> > QTAILQ_INSERT_TAIL(&exports, exp, next);
> > - nbd_export_get(exp);
> > +
>
> Is there any consequence to this changed ordering in grabbing the reference
> vs. updating the list?
No intended consequences, but if Max is right that the code (before and
after this series) lacks some locking, it might make a theoretical
difference. If it does, the new code is safer than the old one. If it
doesn't, it's just more consistent with the order I'm used to see in
other places: First take the reference, then use it.
Kevin
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 14/22] block/export: Move AioContext from NBDExport to BlockExport
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (12 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 13/22] block/export: Move refcount from NBDExport to BlockExport Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 14:56 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 15/22] block/export: Move device to BlockExportOptions Kevin Wolf
` (7 subsequent siblings)
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 6 ++++++
nbd/server.c | 26 +++++++++++++-------------
2 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index f44290a4a2..5459f79469 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -33,6 +33,12 @@ struct BlockExport {
* the export.
*/
int refcount;
+
+ /*
+ * The AioContex whose lock needs to be held while calling
+ * BlockExportDriver callbacks.
+ */
+ AioContext *ctx;
};
extern const BlockExportDriver blk_exp_nbd;
diff --git a/nbd/server.c b/nbd/server.c
index 2bf30bb731..b735a68429 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -92,8 +92,6 @@ struct NBDExport {
QTAILQ_HEAD(, NBDClient) clients;
QTAILQ_ENTRY(NBDExport) next;
- AioContext *ctx;
-
BlockBackend *eject_notifier_blk;
Notifier eject_notifier;
@@ -1333,8 +1331,8 @@ static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
}
/* Attach the channel to the same AioContext as the export */
- if (client->exp && client->exp->ctx) {
- qio_channel_attach_aio_context(client->ioc, client->exp->ctx);
+ if (client->exp && client->exp->common.ctx) {
+ qio_channel_attach_aio_context(client->ioc, client->exp->common.ctx);
}
assert(!client->optlen);
@@ -1466,7 +1464,7 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
trace_nbd_blk_aio_attached(exp->name, ctx);
- exp->ctx = ctx;
+ exp->common.ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_attach_aio_context(client->ioc, ctx);
@@ -1484,13 +1482,13 @@ static void blk_aio_detach(void *opaque)
NBDExport *exp = opaque;
NBDClient *client;
- trace_nbd_blk_aio_detach(exp->name, exp->ctx);
+ trace_nbd_blk_aio_detach(exp->name, exp->common.ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_detach_aio_context(client->ioc);
}
- exp->ctx = NULL;
+ exp->common.ctx = NULL;
}
static void nbd_eject_notifier(Notifier *n, void *data)
@@ -1498,7 +1496,7 @@ static void nbd_eject_notifier(Notifier *n, void *data)
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
AioContext *aio_context;
- aio_context = exp->ctx;
+ aio_context = exp->common.ctx;
aio_context_acquire(aio_context);
nbd_export_close(exp);
aio_context_release(aio_context);
@@ -1534,10 +1532,13 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
return NULL;
}
+ ctx = bdrv_get_aio_context(bs);
+
exp = g_new0(NBDExport, 1);
exp->common = (BlockExport) {
.drv = &blk_exp_nbd,
.refcount = 1,
+ .ctx = ctx,
};
/*
@@ -1547,7 +1548,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
* ctx was acquired in the caller.
*/
assert(name && strlen(name) <= NBD_MAX_STRING_SIZE);
- ctx = bdrv_get_aio_context(bs);
+
bdrv_invalidate_cache(bs, NULL);
/* Don't allow resize while the NBD server is running, otherwise we don't
@@ -1622,7 +1623,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
assert(strlen(exp->export_bitmap_context) < NBD_MAX_STRING_SIZE);
}
- exp->ctx = ctx;
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
blk_exp_ref(&exp->common);
@@ -1653,7 +1653,7 @@ NBDExport *nbd_export_find(const char *name)
AioContext *
nbd_export_aio_context(NBDExport *exp)
{
- return exp->ctx;
+ return exp->common.ctx;
}
void nbd_export_close(NBDExport *exp)
@@ -1738,7 +1738,7 @@ void nbd_export_close_all(void)
AioContext *aio_context;
QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
- aio_context = exp->ctx;
+ aio_context = exp->common.ctx;
aio_context_acquire(aio_context);
nbd_export_close(exp);
aio_context_release(aio_context);
@@ -2519,7 +2519,7 @@ static void nbd_client_receive_next_request(NBDClient *client)
if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
nbd_client_get(client);
client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
- aio_co_schedule(client->exp->ctx, client->recv_coroutine);
+ aio_co_schedule(client->exp->common.ctx, client->recv_coroutine);
}
}
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 14/22] block/export: Move AioContext from NBDExport to BlockExport
2020-08-13 16:29 ` [RFC PATCH 14/22] block/export: Move AioContext " Kevin Wolf
@ 2020-08-17 14:56 ` Max Reitz
2020-08-17 15:22 ` Kevin Wolf
0 siblings, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 14:56 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 2054 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 6 ++++++
> nbd/server.c | 26 +++++++++++++-------------
> 2 files changed, 19 insertions(+), 13 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
> diff --git a/include/block/export.h b/include/block/export.h
> index f44290a4a2..5459f79469 100644
> --- a/include/block/export.h
> +++ b/include/block/export.h
> @@ -33,6 +33,12 @@ struct BlockExport {
> * the export.
> */
> int refcount;
> +
> + /*
> + * The AioContex whose lock needs to be held while calling
*AioContext
> + * BlockExportDriver callbacks.
Hm. But other blk_exp_* functions (i.e. the refcount manipulation
functions) are fair game?
> + */
> + AioContext *ctx;
> };
>
> extern const BlockExportDriver blk_exp_nbd;
> diff --git a/nbd/server.c b/nbd/server.c
> index 2bf30bb731..b735a68429 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
[...]
> @@ -1466,7 +1464,7 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
>
> trace_nbd_blk_aio_attached(exp->name, ctx);
>
> - exp->ctx = ctx;
> + exp->common.ctx = ctx;
(Not sure if Ḯ’m missing anything to that regard), but perhaps after
patch 21 we can move this part to the common block export code, and
maybe make it call a BlockExportDriver callback (that handles the rest
of this function).
> QTAILQ_FOREACH(client, &exp->clients, next) {
> qio_channel_attach_aio_context(client->ioc, ctx);
> @@ -1484,13 +1482,13 @@ static void blk_aio_detach(void *opaque)
> NBDExport *exp = opaque;
> NBDClient *client;
>
> - trace_nbd_blk_aio_detach(exp->name, exp->ctx);
> + trace_nbd_blk_aio_detach(exp->name, exp->common.ctx);
>
> QTAILQ_FOREACH(client, &exp->clients, next) {
> qio_channel_detach_aio_context(client->ioc);
> }
>
> - exp->ctx = NULL;
> + exp->common.ctx = NULL;
(same here)
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 14/22] block/export: Move AioContext from NBDExport to BlockExport
2020-08-17 14:56 ` Max Reitz
@ 2020-08-17 15:22 ` Kevin Wolf
2020-08-17 15:47 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 15:22 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 2541 bytes --]
Am 17.08.2020 um 16:56 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > include/block/export.h | 6 ++++++
> > nbd/server.c | 26 +++++++++++++-------------
> > 2 files changed, 19 insertions(+), 13 deletions(-)
>
> Reviewed-by: Max Reitz <mreitz@redhat.com>
>
> > diff --git a/include/block/export.h b/include/block/export.h
> > index f44290a4a2..5459f79469 100644
> > --- a/include/block/export.h
> > +++ b/include/block/export.h
> > @@ -33,6 +33,12 @@ struct BlockExport {
> > * the export.
> > */
> > int refcount;
> > +
> > + /*
> > + * The AioContex whose lock needs to be held while calling
>
> *AioContext
>
> > + * BlockExportDriver callbacks.
>
> Hm. But other blk_exp_* functions (i.e. the refcount manipulation
> functions) are fair game?
Hmm... The assumption was the ref/unref are only called from the main
thread, but maybe that's not true? So maybe blk_exp_*() shouldn't lock
the AioContext internally, but require that the lock is already held, so
that they can be called both from within the AioContext (where we don't
want to lock a second tim) and from the main context.
I also guess we need a separate mutex to protect the exports list if
unref can be called from different threads.
And probably the existing NBD server code has already the same problems
with respect to different AioContexts.
> > + */
> > + AioContext *ctx;
> > };
> >
> > extern const BlockExportDriver blk_exp_nbd;
> > diff --git a/nbd/server.c b/nbd/server.c
> > index 2bf30bb731..b735a68429 100644
> > --- a/nbd/server.c
> > +++ b/nbd/server.c
>
> [...]
>
> > @@ -1466,7 +1464,7 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
> >
> > trace_nbd_blk_aio_attached(exp->name, ctx);
> >
> > - exp->ctx = ctx;
> > + exp->common.ctx = ctx;
>
> (Not sure if Ḯ’m missing anything to that regard), but perhaps after
> patch 21 we can move this part to the common block export code, and
> maybe make it call a BlockExportDriver callback (that handles the rest
> of this function).
Could probably be done. Not every export driver may support switching
AioContexts, but we can make it conditional on having the callback.
So do I understand right from your comments to the series in general
that you would prefer to make this series more complete, even if that
means that it becomes quite a bit longer?
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 14/22] block/export: Move AioContext from NBDExport to BlockExport
2020-08-17 15:22 ` Kevin Wolf
@ 2020-08-17 15:47 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 15:47 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 3718 bytes --]
On 17.08.20 17:22, Kevin Wolf wrote:
> Am 17.08.2020 um 16:56 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> include/block/export.h | 6 ++++++
>>> nbd/server.c | 26 +++++++++++++-------------
>>> 2 files changed, 19 insertions(+), 13 deletions(-)
>>
>> Reviewed-by: Max Reitz <mreitz@redhat.com>
>>
>>> diff --git a/include/block/export.h b/include/block/export.h
>>> index f44290a4a2..5459f79469 100644
>>> --- a/include/block/export.h
>>> +++ b/include/block/export.h
>>> @@ -33,6 +33,12 @@ struct BlockExport {
>>> * the export.
>>> */
>>> int refcount;
>>> +
>>> + /*
>>> + * The AioContex whose lock needs to be held while calling
>>
>> *AioContext
>>
>>> + * BlockExportDriver callbacks.
>>
>> Hm. But other blk_exp_* functions (i.e. the refcount manipulation
>> functions) are fair game?
>
> Hmm... The assumption was the ref/unref are only called from the main
> thread, but maybe that's not true? So maybe blk_exp_*() shouldn't lock
> the AioContext internally, but require that the lock is already held, so
> that they can be called both from within the AioContext (where we don't
> want to lock a second tim) and from the main context.
>
> I also guess we need a separate mutex to protect the exports list if
> unref can be called from different threads.
>
> And probably the existing NBD server code has already the same problems
> with respect to different AioContexts.
>
>>> + */
>>> + AioContext *ctx;
>>> };
>>>
>>> extern const BlockExportDriver blk_exp_nbd;
>>> diff --git a/nbd/server.c b/nbd/server.c
>>> index 2bf30bb731..b735a68429 100644
>>> --- a/nbd/server.c
>>> +++ b/nbd/server.c
>>
>> [...]
>>
>>> @@ -1466,7 +1464,7 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
>>>
>>> trace_nbd_blk_aio_attached(exp->name, ctx);
>>>
>>> - exp->ctx = ctx;
>>> + exp->common.ctx = ctx;
>>
>> (Not sure if Ḯ’m missing anything to that regard), but perhaps after
>> patch 21 we can move this part to the common block export code, and
>> maybe make it call a BlockExportDriver callback (that handles the rest
>> of this function).
>
> Could probably be done. Not every export driver may support switching
> AioContexts, but we can make it conditional on having the callback.
Good point.
> So do I understand right from your comments to the series in general
> that you would prefer to make this series more complete, even if that
> means that it becomes quite a bit longer?
I’m not necessarily asking for this now, I’m mostly asking whether you
have the same idea as me on things like this. I don’t mind too much
leaving this in an unfinished state as long as we both agree that it’s
kind of unfinished.
Sorry if this is a bit frustrating to you because you wrote in the cover
letter that indeed you are unsure about how complete you want to do
this. The problem is that I don’t know exactly what things you’re
referring to, so I just point out everything that stands out to me. If
you’re aware of those things, and we can work on them later, then that’s OK.
OTOH... Yes, from a design standpoint, I think it makes sense to pull
out as much specialized code as possible from NBD into the generalized
block export code. But I say that as a reviewer. You would have to do
that, so I want to leave it to you how much work you think is reasonable
to put into that. Leaving a couple of rough edges here and there
shouldn’t be a problem. (Or maybe leaving something to me for when I
add fuse export code.)
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 15/22] block/export: Move device to BlockExportOptions
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (13 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 14/22] block/export: Move AioContext " Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-17 15:13 ` Max Reitz
2020-08-19 21:13 ` Eric Blake
2020-08-13 16:29 ` [RFC PATCH 16/22] block/export: Allocate BlockExport in blk_exp_add() Kevin Wolf
` (6 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Every block export needs a block node to export, so move the 'device'
option from BlockExportOptionsNbd to BlockExportOptions.
To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
to be wrapped by a new type NbdServerAddOptions that adds 'device' back
because nbd-server-add doesn't use the BlockExportOptions base type.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 27 +++++++++++++++++++++------
block/export/export.c | 26 ++++++++++++++++++++------
block/monitor/block-hmp-cmds.c | 6 +++---
blockdev-nbd.c | 4 ++--
qemu-nbd.c | 2 +-
5 files changed, 47 insertions(+), 18 deletions(-)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 4ce163411f..d68f3bf87e 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -62,9 +62,8 @@
##
# @BlockExportOptionsNbd:
#
-# An NBD block export.
-#
-# @device: The device name or node name of the node to be exported
+# An NBD block export (options shared between nbd-server-add and the NBD branch
+# of block-export-add).
#
# @name: Export name. If unspecified, the @device parameter is used as the
# export name. (Since 2.12)
@@ -82,8 +81,21 @@
# Since: 5.0
##
{ 'struct': 'BlockExportOptionsNbd',
- 'data': {'device': 'str', '*name': 'str', '*description': 'str',
- '*writable': 'bool', '*bitmap': 'str' } }
+ 'data': { '*name': 'str', '*description': 'str',
+ '*writable': 'bool', '*bitmap': 'str' } }
+
+##
+# @NbdServerAddOptions:
+#
+# An NBD block export.
+#
+# @device: The device name or node name of the node to be exported
+#
+# Since: 5.0
+##
+{ 'struct': 'NbdServerAddOptions',
+ 'base': 'BlockExportOptionsNbd',
+ 'data': { 'device': 'str' } }
##
# @nbd-server-add:
@@ -96,7 +108,7 @@
# Since: 1.3.0
##
{ 'command': 'nbd-server-add',
- 'data': 'BlockExportOptionsNbd', 'boxed': true }
+ 'data': 'NbdServerAddOptions', 'boxed': true }
##
# @NbdServerRemoveMode:
@@ -167,6 +179,8 @@
# Describes a block export, i.e. how single node should be exported on an
# external interface.
#
+# @device: The device name or node name of the node to be exported
+#
# @writethrough: If true, caches are flushed after every write request to the
# export before completion is signalled. (since: 5.2;
# default: false)
@@ -175,6 +189,7 @@
##
{ 'union': 'BlockExportOptions',
'base': { 'type': 'BlockExportType',
+ 'device': 'str',
'*writethrough': 'bool' },
'discriminator': 'type',
'data': {
diff --git a/block/export/export.c b/block/export/export.c
index 1d5de564c7..ef86bf892b 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -68,15 +68,26 @@ void qmp_block_export_add(BlockExportOptions *export, Error **errp)
blk_exp_add(export, errp);
}
-void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
+void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
{
BlockExport *export;
BlockDriverState *bs;
BlockBackend *on_eject_blk;
- BlockExportOptions export_opts = {
- .type = BLOCK_EXPORT_TYPE_NBD,
- .u.nbd = *arg,
+ BlockExportOptions *export_opts = g_new(BlockExportOptions, 1);
+ *export_opts = (BlockExportOptions) {
+ .type = BLOCK_EXPORT_TYPE_NBD,
+ .device = g_strdup(arg->device),
+ .u.nbd = {
+ .has_name = arg->has_name,
+ .name = g_strdup(arg->name),
+ .has_description = arg->has_description,
+ .description = g_strdup(arg->description),
+ .has_writable = arg->has_writable,
+ .writable = arg->writable,
+ .has_bitmap = arg->has_bitmap,
+ .bitmap = g_strdup(arg->bitmap),
+ },
};
/*
@@ -89,9 +100,9 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
arg->writable = false;
}
- export = blk_exp_add(&export_opts, errp);
+ export = blk_exp_add(export_opts, errp);
if (!export) {
- return;
+ goto fail;
}
/*
@@ -102,4 +113,7 @@ void qmp_nbd_server_add(BlockExportOptionsNbd *arg, Error **errp)
if (on_eject_blk) {
nbd_export_set_on_eject_blk(export, on_eject_blk);
}
+
+fail:
+ qapi_free_BlockExportOptions(export_opts);
}
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index a651954e16..6c823234a9 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -398,7 +398,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
Error *local_err = NULL;
BlockInfoList *block_list, *info;
SocketAddress *addr;
- BlockExportOptionsNbd export;
+ NbdServerAddOptions export;
if (writable && !all) {
error_setg(&local_err, "-w only valid together with -a");
@@ -431,7 +431,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
continue;
}
- export = (BlockExportOptionsNbd) {
+ export = (NbdServerAddOptions) {
.device = info->value->device,
.has_writable = true,
.writable = writable,
@@ -458,7 +458,7 @@ void hmp_nbd_server_add(Monitor *mon, const QDict *qdict)
bool writable = qdict_get_try_bool(qdict, "writable", false);
Error *local_err = NULL;
- BlockExportOptionsNbd export = {
+ NbdServerAddOptions export = {
.device = (char *) device,
.has_name = !!name,
.name = (char *) name,
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index a8b7b785e7..5e97975c80 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -188,7 +188,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
}
if (!arg->has_name) {
- arg->name = arg->device;
+ arg->name = exp_args->device;
}
if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
@@ -206,7 +206,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
return NULL;
}
- bs = bdrv_lookup_bs(arg->device, arg->device, errp);
+ bs = bdrv_lookup_bs(exp_args->device, exp_args->device, errp);
if (!bs) {
return NULL;
}
diff --git a/qemu-nbd.c b/qemu-nbd.c
index d967b8fcb9..f31868708c 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -1055,10 +1055,10 @@ int main(int argc, char **argv)
export_opts = g_new(BlockExportOptions, 1);
*export_opts = (BlockExportOptions) {
.type = BLOCK_EXPORT_TYPE_NBD,
+ .device = g_strdup(bdrv_get_node_name(bs)),
.has_writethrough = true,
.writethrough = writethrough,
.u.nbd = {
- .device = g_strdup(bdrv_get_node_name(bs)),
.has_name = true,
.name = g_strdup(export_name),
.has_description = !!export_description,
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 15/22] block/export: Move device to BlockExportOptions
2020-08-13 16:29 ` [RFC PATCH 15/22] block/export: Move device to BlockExportOptions Kevin Wolf
@ 2020-08-17 15:13 ` Max Reitz
2020-08-17 15:27 ` Kevin Wolf
2020-08-19 21:13 ` Eric Blake
1 sibling, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-17 15:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1787 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Every block export needs a block node to export, so move the 'device'
> option from BlockExportOptionsNbd to BlockExportOptions.
>
> To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
> to be wrapped by a new type NbdServerAddOptions that adds 'device' back
> because nbd-server-add doesn't use the BlockExportOptions base type.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 27 +++++++++++++++++++++------
> block/export/export.c | 26 ++++++++++++++++++++------
> block/monitor/block-hmp-cmds.c | 6 +++---
> blockdev-nbd.c | 4 ++--
> qemu-nbd.c | 2 +-
> 5 files changed, 47 insertions(+), 18 deletions(-)
(Code diff looks good, just a question on the interface:)
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index 4ce163411f..d68f3bf87e 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
[...]
> @@ -167,6 +179,8 @@
> # Describes a block export, i.e. how single node should be exported on an
> # external interface.
> #
> +# @device: The device name or node name of the node to be exported
> +#
Wouldn’t it be better to restrict ourselves to a node name here?
(Bluntly ignoring the fact that doing so would make this patch an
incompatible change, which would require some reordering in this series,
unless we decide to just ignore that intra-series incompatibility.)
OTOH... What does “better” mean. It won’t hurt anyone to keep this as
@device. It’s just that I feel like if we had no legacy burden and did
this all from scratch, we would just make it @node-name.
Did you deliberately decide against @node-name?
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 15/22] block/export: Move device to BlockExportOptions
2020-08-17 15:13 ` Max Reitz
@ 2020-08-17 15:27 ` Kevin Wolf
2020-08-17 15:49 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-17 15:27 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 2233 bytes --]
Am 17.08.2020 um 17:13 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > Every block export needs a block node to export, so move the 'device'
> > option from BlockExportOptionsNbd to BlockExportOptions.
> >
> > To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
> > to be wrapped by a new type NbdServerAddOptions that adds 'device' back
> > because nbd-server-add doesn't use the BlockExportOptions base type.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 27 +++++++++++++++++++++------
> > block/export/export.c | 26 ++++++++++++++++++++------
> > block/monitor/block-hmp-cmds.c | 6 +++---
> > blockdev-nbd.c | 4 ++--
> > qemu-nbd.c | 2 +-
> > 5 files changed, 47 insertions(+), 18 deletions(-)
>
> (Code diff looks good, just a question on the interface:)
>
> > diff --git a/qapi/block-export.json b/qapi/block-export.json
> > index 4ce163411f..d68f3bf87e 100644
> > --- a/qapi/block-export.json
> > +++ b/qapi/block-export.json
>
> [...]
>
> > @@ -167,6 +179,8 @@
> > # Describes a block export, i.e. how single node should be exported on an
> > # external interface.
> > #
> > +# @device: The device name or node name of the node to be exported
> > +#
>
> Wouldn’t it be better to restrict ourselves to a node name here?
> (Bluntly ignoring the fact that doing so would make this patch an
> incompatible change, which would require some reordering in this series,
> unless we decide to just ignore that intra-series incompatibility.)
We already have intra-series incompatibility, so I wouldn't mind that.
> OTOH... What does “better” mean. It won’t hurt anyone to keep this as
> @device. It’s just that I feel like if we had no legacy burden and did
> this all from scratch, we would just make it @node-name.
>
> Did you deliberately decide against @node-name?
At first I thought I could still share code between nbd-server-add and
block-export-add, but that's not the case. Then I guess the only other
reason I have is consistency with other QMP commands. I won't pretend
it's a strong one.
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 15/22] block/export: Move device to BlockExportOptions
2020-08-17 15:27 ` Kevin Wolf
@ 2020-08-17 15:49 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-17 15:49 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
[-- Attachment #1.1: Type: text/plain, Size: 2566 bytes --]
On 17.08.20 17:27, Kevin Wolf wrote:
> Am 17.08.2020 um 17:13 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> Every block export needs a block node to export, so move the 'device'
>>> option from BlockExportOptionsNbd to BlockExportOptions.
>>>
>>> To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
>>> to be wrapped by a new type NbdServerAddOptions that adds 'device' back
>>> because nbd-server-add doesn't use the BlockExportOptions base type.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> qapi/block-export.json | 27 +++++++++++++++++++++------
>>> block/export/export.c | 26 ++++++++++++++++++++------
>>> block/monitor/block-hmp-cmds.c | 6 +++---
>>> blockdev-nbd.c | 4 ++--
>>> qemu-nbd.c | 2 +-
>>> 5 files changed, 47 insertions(+), 18 deletions(-)
>>
>> (Code diff looks good, just a question on the interface:)
>>
>>> diff --git a/qapi/block-export.json b/qapi/block-export.json
>>> index 4ce163411f..d68f3bf87e 100644
>>> --- a/qapi/block-export.json
>>> +++ b/qapi/block-export.json
>>
>> [...]
>>
>>> @@ -167,6 +179,8 @@
>>> # Describes a block export, i.e. how single node should be exported on an
>>> # external interface.
>>> #
>>> +# @device: The device name or node name of the node to be exported
>>> +#
>>
>> Wouldn’t it be better to restrict ourselves to a node name here?
>> (Bluntly ignoring the fact that doing so would make this patch an
>> incompatible change, which would require some reordering in this series,
>> unless we decide to just ignore that intra-series incompatibility.)
>
> We already have intra-series incompatibility, so I wouldn't mind that.
>
>> OTOH... What does “better” mean. It won’t hurt anyone to keep this as
>> @device. It’s just that I feel like if we had no legacy burden and did
>> this all from scratch, we would just make it @node-name.
>>
>> Did you deliberately decide against @node-name?
>
> At first I thought I could still share code between nbd-server-add and
> block-export-add, but that's not the case. Then I guess the only other
> reason I have is consistency with other QMP commands. I won't pretend
> it's a strong one.
If “using @node-name would be more natural” doesn’t resonate with you,
then I suppose we should just leave it as @device. It isn’t harder to
handle for qemu, and maybe it makes transitioning easier for some users
(although I can’t quite imagine how).
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 15/22] block/export: Move device to BlockExportOptions
2020-08-13 16:29 ` [RFC PATCH 15/22] block/export: Move device to BlockExportOptions Kevin Wolf
2020-08-17 15:13 ` Max Reitz
@ 2020-08-19 21:13 ` Eric Blake
1 sibling, 0 replies; 90+ messages in thread
From: Eric Blake @ 2020-08-19 21:13 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel, mreitz
On 8/13/20 11:29 AM, Kevin Wolf wrote:
> Every block export needs a block node to export, so move the 'device'
> option from BlockExportOptionsNbd to BlockExportOptions.
>
> To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
> to be wrapped by a new type NbdServerAddOptions that adds 'device' back
> because nbd-server-add doesn't use the BlockExportOptions base type.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> +++ b/qapi/block-export.json
> @@ -62,9 +62,8 @@
> ##
> # @BlockExportOptionsNbd:
> #
> -# An NBD block export.
> -#
> -# @device: The device name or node name of the node to be exported
> +# An NBD block export (options shared between nbd-server-add and the NBD branch
> +# of block-export-add).
> #
> # @name: Export name. If unspecified, the @device parameter is used as the
> # export name. (Since 2.12)
> @@ -82,8 +81,21 @@
> # Since: 5.0
> ##
> { 'struct': 'BlockExportOptionsNbd',
> - 'data': {'device': 'str', '*name': 'str', '*description': 'str',
> - '*writable': 'bool', '*bitmap': 'str' } }
> + 'data': { '*name': 'str', '*description': 'str',
> + '*writable': 'bool', '*bitmap': 'str' } }
> +
> +##
> +# @NbdServerAddOptions:
> +#
> +# An NBD block export.
> +#
> +# @device: The device name or node name of the node to be exported
> +#
> +# Since: 5.0
5.2, now?
> +##
> +{ 'struct': 'NbdServerAddOptions',
> + 'base': 'BlockExportOptionsNbd',
> + 'data': { 'device': 'str' } }
I understand why nbd sticks with device that can name device or node, but...
>
> ##
> # @nbd-server-add:
> @@ -96,7 +108,7 @@
> # Since: 1.3.0
> ##
> { 'command': 'nbd-server-add',
> - 'data': 'BlockExportOptionsNbd', 'boxed': true }
> + 'data': 'NbdServerAddOptions', 'boxed': true }
>
> ##
> # @NbdServerRemoveMode:
> @@ -167,6 +179,8 @@
> # Describes a block export, i.e. how single node should be exported on an
> # external interface.
> #
> +# @device: The device name or node name of the node to be exported
> +#
> # @writethrough: If true, caches are flushed after every write request to the
> # export before completion is signalled. (since: 5.2;
> # default: false)
> @@ -175,6 +189,7 @@
> ##
> { 'union': 'BlockExportOptions',
> 'base': { 'type': 'BlockExportType',
> + 'device': 'str',
for block export, I'd prefer that we mandate node name only, and naming
it @node-name (rather than @device) feels nicer, for something that only
new code will be using (that is, we should be encouraging the use of
node names, especially now that libvirt has finally made that leap).
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 16/22] block/export: Allocate BlockExport in blk_exp_add()
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (14 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 15/22] block/export: Move device to BlockExportOptions Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-18 14:25 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 17/22] block/export: Add blk_exp_close_all(_type) Kevin Wolf
` (5 subsequent siblings)
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Instead of letting the driver allocate and return the BlockExport
object, allocate it already in blk_exp_add() and pass it. This allows us
to initialise the generic part before calling into the driver so that
the driver can just use these values instead of having to parse the
options a second time.
For symmetry, move freeing the BlockExport to blk_exp_unref().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 3 ++-
include/block/nbd.h | 11 ++++++-----
block/export/export.c | 17 ++++++++++++++++-
blockdev-nbd.c | 24 +++++++++++++-----------
nbd/server.c | 30 +++++++++++++-----------------
5 files changed, 50 insertions(+), 35 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index 5459f79469..597fc58245 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -20,7 +20,8 @@ typedef struct BlockExport BlockExport;
typedef struct BlockExportDriver {
BlockExportType type;
- BlockExport *(*create)(BlockExportOptions *, Error **);
+ size_t instance_size;
+ int (*create)(BlockExport *, BlockExportOptions *, Error **);
void (*delete)(BlockExport *);
} BlockExportDriver;
diff --git a/include/block/nbd.h b/include/block/nbd.h
index af8509ab70..602536feb2 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -328,11 +328,12 @@ int nbd_errno_to_system_errno(int err);
typedef struct NBDExport NBDExport;
typedef struct NBDClient NBDClient;
-BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp);
-NBDExport *nbd_export_new(BlockDriverState *bs,
- const char *name, const char *desc,
- const char *bitmap, bool readonly, bool shared,
- bool writethrough, Error **errp);
+int nbd_export_create(BlockExport *exp, BlockExportOptions *exp_args,
+ Error **errp);
+int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
+ const char *name, const char *desc,
+ const char *bitmap, bool readonly, bool shared,
+ bool writethrough, Error **errp);
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
diff --git a/block/export/export.c b/block/export/export.c
index ef86bf892b..9de108cbc1 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -39,6 +39,8 @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
{
const BlockExportDriver *drv;
+ BlockExport *exp;
+ int ret;
drv = blk_exp_find_driver(export->type);
if (!drv) {
@@ -46,7 +48,19 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return NULL;
}
- return drv->create(export, errp);
+ exp = g_malloc0(drv->instance_size);
+ *exp = (BlockExport) {
+ .drv = &blk_exp_nbd,
+ .refcount = 1,
+ };
+
+ ret = drv->create(exp, export, errp);
+ if (ret < 0) {
+ g_free(exp);
+ return NULL;
+ }
+
+ return exp;
}
void blk_exp_ref(BlockExport *exp)
@@ -60,6 +74,7 @@ void blk_exp_unref(BlockExport *exp)
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
exp->drv->delete(exp);
+ g_free(exp);
}
}
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 5e97975c80..f97deba424 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -173,18 +173,19 @@ void qmp_nbd_server_start(SocketAddressLegacy *addr,
qapi_free_SocketAddress(addr_flat);
}
-BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
+int nbd_export_create(BlockExport *exp, BlockExportOptions *exp_args,
+ Error **errp)
{
BlockExportOptionsNbd *arg = &exp_args->u.nbd;
BlockDriverState *bs = NULL;
- NBDExport *exp = NULL;
AioContext *aio_context;
+ int ret;
assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
if (!nbd_server && !is_qemu_nbd) {
error_setg(errp, "NBD server not running");
- return NULL;
+ return -EINVAL;
}
if (!arg->has_name) {
@@ -193,22 +194,22 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
if (strlen(arg->name) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "export name '%s' too long", arg->name);
- return NULL;
+ return -EINVAL;
}
if (arg->description && strlen(arg->description) > NBD_MAX_STRING_SIZE) {
error_setg(errp, "description '%s' too long", arg->description);
- return NULL;
+ return -EINVAL;
}
if (nbd_export_find(arg->name)) {
error_setg(errp, "NBD server already has export named '%s'", arg->name);
- return NULL;
+ return -EEXIST;
}
bs = bdrv_lookup_bs(exp_args->device, exp_args->device, errp);
if (!bs) {
- return NULL;
+ return -ENOENT;
}
aio_context = bdrv_get_aio_context(bs);
@@ -218,14 +219,15 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
arg->writable = false;
}
if (bdrv_is_read_only(bs) && arg->writable) {
+ ret = -EINVAL;
error_setg(errp, "Cannot export read-only node as writable");
goto out;
}
- exp = nbd_export_new(bs, arg->name, arg->description, arg->bitmap,
+ ret = nbd_export_new(exp, bs, arg->name, arg->description, arg->bitmap,
!arg->writable, !arg->writable,
exp_args->writethrough, errp);
- if (!exp) {
+ if (ret < 0) {
goto out;
}
@@ -234,10 +236,10 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
* the strong reference that is @exp. */
blk_exp_unref((BlockExport*) exp);
+ ret = 0;
out:
aio_context_release(aio_context);
- /* TODO Remove the cast: Move to server.c which can access fields of exp */
- return (BlockExport*) exp;
+ return ret;
}
void qmp_nbd_server_remove(const char *name,
diff --git a/nbd/server.c b/nbd/server.c
index b735a68429..6a58297557 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1513,14 +1513,14 @@ void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
blk_add_remove_bs_notifier(blk, &nbd_exp->eject_notifier);
}
-NBDExport *nbd_export_new(BlockDriverState *bs,
- const char *name, const char *desc,
- const char *bitmap, bool readonly, bool shared,
- bool writethrough, Error **errp)
+int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
+ const char *name, const char *desc,
+ const char *bitmap, bool readonly, bool shared,
+ bool writethrough, Error **errp)
{
+ NBDExport *exp = container_of(blk_exp, NBDExport, common);
AioContext *ctx;
BlockBackend *blk;
- NBDExport *exp;
int64_t size;
uint64_t perm;
int ret;
@@ -1529,17 +1529,11 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
if (size < 0) {
error_setg_errno(errp, -size,
"Failed to determine the NBD export's length");
- return NULL;
+ return size;
}
ctx = bdrv_get_aio_context(bs);
-
- exp = g_new0(NBDExport, 1);
- exp->common = (BlockExport) {
- .drv = &blk_exp_nbd,
- .refcount = 1,
- .ctx = ctx,
- };
+ blk_exp->ctx = ctx;
/*
* NBD exports are used for non-shared storage migration. Make sure
@@ -1599,16 +1593,19 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
}
if (bm == NULL) {
+ ret = -ENOENT;
error_setg(errp, "Bitmap '%s' is not found", bitmap);
goto fail;
}
if (bdrv_dirty_bitmap_check(bm, BDRV_BITMAP_ALLOW_RO, errp)) {
+ ret = -EINVAL;
goto fail;
}
if (readonly && bdrv_is_writable(bs) &&
bdrv_dirty_bitmap_enabled(bm)) {
+ ret = -EINVAL;
error_setg(errp,
"Enabled bitmap '%s' incompatible with readonly export",
bitmap);
@@ -1628,14 +1625,13 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
blk_exp_ref(&exp->common);
QTAILQ_INSERT_TAIL(&exports, exp, next);
- return exp;
+ return 0;
fail:
blk_unref(blk);
g_free(exp->name);
g_free(exp->description);
- g_free(exp);
- return NULL;
+ return ret;
}
NBDExport *nbd_export_find(const char *name)
@@ -1722,12 +1718,12 @@ static void nbd_export_delete(BlockExport *blk_exp)
}
QTAILQ_REMOVE(&closed_exports, exp, next);
- g_free(exp);
aio_wait_kick();
}
const BlockExportDriver blk_exp_nbd = {
.type = BLOCK_EXPORT_TYPE_NBD,
+ .instance_size = sizeof(NBDExport),
.create = nbd_export_create,
.delete = nbd_export_delete,
};
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 16/22] block/export: Allocate BlockExport in blk_exp_add()
2020-08-13 16:29 ` [RFC PATCH 16/22] block/export: Allocate BlockExport in blk_exp_add() Kevin Wolf
@ 2020-08-18 14:25 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-18 14:25 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1458 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Instead of letting the driver allocate and return the BlockExport
> object, allocate it already in blk_exp_add() and pass it. This allows us
> to initialise the generic part before calling into the driver so that
> the driver can just use these values instead of having to parse the
> options a second time.
>
> For symmetry, move freeing the BlockExport to blk_exp_unref().
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 3 ++-
> include/block/nbd.h | 11 ++++++-----
> block/export/export.c | 17 ++++++++++++++++-
> blockdev-nbd.c | 24 +++++++++++++-----------
> nbd/server.c | 30 +++++++++++++-----------------
> 5 files changed, 50 insertions(+), 35 deletions(-)
[...]
> diff --git a/block/export/export.c b/block/export/export.c
> index ef86bf892b..9de108cbc1 100644
> --- a/block/export/export.c
> +++ b/block/export/export.c
[...]
> @@ -46,7 +48,19 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
> return NULL;
> }
>
> - return drv->create(export, errp);
assert(drv->instance_size >= sizeof(BlockExport)) might be nice before
dereferencing *exp.
With that:
Reviewed-by: Max Reitz <mreitz@redhat.com>
> + exp = g_malloc0(drv->instance_size);
> + *exp = (BlockExport) {
> + .drv = &blk_exp_nbd,
> + .refcount = 1,
> + };
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 17/22] block/export: Add blk_exp_close_all(_type)
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (15 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 16/22] block/export: Allocate BlockExport in blk_exp_add() Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-18 15:00 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 18/22] block/export: Add 'id' option to block-export-add Kevin Wolf
` (4 subsequent siblings)
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
This adds a function to shut down all block exports, and another one to
shut down the block exports of a single type. The latter is used for now
when stopping the NBD server. As soon as we implement support for
multiple NBD servers, we'll need a per-server list of exports and it
will be replaced by a function using that.
As a side effect, the BlockExport layer has a list tracking all existing
exports now. closed_exports loses its only user and can go away.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 8 +++++++
include/block/nbd.h | 2 --
block.c | 2 +-
block/export/export.c | 52 ++++++++++++++++++++++++++++++++++++++++++
blockdev-nbd.c | 2 +-
nbd/server.c | 34 ++++-----------------------
qemu-nbd.c | 2 +-
7 files changed, 68 insertions(+), 34 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index 597fc58245..1698b68f09 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -15,6 +15,7 @@
#define BLOCK_EXPORT_H
#include "qapi/qapi-types-block-export.h"
+#include "qemu/queue.h"
typedef struct BlockExport BlockExport;
@@ -23,6 +24,7 @@ typedef struct BlockExportDriver {
size_t instance_size;
int (*create)(BlockExport *, BlockExportOptions *, Error **);
void (*delete)(BlockExport *);
+ void (*request_shutdown)(BlockExport *);
} BlockExportDriver;
struct BlockExport {
@@ -40,6 +42,9 @@ struct BlockExport {
* BlockExportDriver callbacks.
*/
AioContext *ctx;
+
+ /* List entry for block_exports */
+ QLIST_ENTRY(BlockExport) next;
};
extern const BlockExportDriver blk_exp_nbd;
@@ -47,5 +52,8 @@ extern const BlockExportDriver blk_exp_nbd;
BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
void blk_exp_ref(BlockExport *exp);
void blk_exp_unref(BlockExport *exp);
+void blk_exp_request_shutdown(BlockExport *exp);
+void blk_exp_close_all(void);
+void blk_exp_close_all_type(BlockExportType type);
#endif
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 602536feb2..91a9d4f96d 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -335,12 +335,10 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
const char *bitmap, bool readonly, bool shared,
bool writethrough, Error **errp);
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
-void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
AioContext *nbd_export_aio_context(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);
-void nbd_export_close_all(void);
void nbd_client_new(QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
diff --git a/block.c b/block.c
index d9ac0e07eb..357c72846e 100644
--- a/block.c
+++ b/block.c
@@ -4424,7 +4424,7 @@ static void bdrv_close(BlockDriverState *bs)
void bdrv_close_all(void)
{
assert(job_next(NULL) == NULL);
- nbd_export_close_all();
+ blk_exp_close_all();
/* Drop references from requests still in flight, such as canceled block
* jobs whose AIO context has not been polled yet */
diff --git a/block/export/export.c b/block/export/export.c
index 9de108cbc1..675db9a8b9 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -24,6 +24,9 @@ static const BlockExportDriver* blk_exp_drivers[] = {
&blk_exp_nbd,
};
+static QLIST_HEAD(, BlockExport) block_exports =
+ QLIST_HEAD_INITIALIZER(block_exports);
+
static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
{
int i;
@@ -60,6 +63,7 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return NULL;
}
+ QLIST_INSERT_HEAD(&block_exports, exp, next);
return exp;
}
@@ -73,11 +77,59 @@ void blk_exp_unref(BlockExport *exp)
{
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
+ QLIST_REMOVE(exp, next);
exp->drv->delete(exp);
g_free(exp);
+ aio_wait_kick();
}
}
+void blk_exp_request_shutdown(BlockExport *exp)
+{
+ AioContext *aio_context = exp->ctx;
+
+ aio_context_acquire(aio_context);
+ exp->drv->request_shutdown(exp);
+ aio_context_release(aio_context);
+}
+
+static bool blk_exp_has_type(BlockExportType type)
+{
+ BlockExport *exp;
+
+ if (type == BLOCK_EXPORT_TYPE__MAX) {
+ return !QLIST_EMPTY(&block_exports);
+ }
+
+ QLIST_FOREACH(exp, &block_exports, next) {
+ if (exp->drv->type == type) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/* type == BLOCK_EXPORT_TYPE__MAX for all types */
+void blk_exp_close_all_type(BlockExportType type)
+{
+ BlockExport *exp, *next;
+
+ QLIST_FOREACH_SAFE(exp, &block_exports, next, next) {
+ if (type != BLOCK_EXPORT_TYPE__MAX && exp->drv->type != type) {
+ continue;
+ }
+ blk_exp_request_shutdown(exp);
+ }
+
+ AIO_WAIT_WHILE(NULL, blk_exp_has_type(type));
+}
+
+void blk_exp_close_all(void)
+{
+ blk_exp_close_all_type(BLOCK_EXPORT_TYPE__MAX);
+}
+
void qmp_block_export_add(BlockExportOptions *export, Error **errp)
{
blk_exp_add(export, errp);
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index f97deba424..1c7aa874ee 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -277,7 +277,7 @@ void qmp_nbd_server_stop(Error **errp)
return;
}
- nbd_export_close_all();
+ blk_exp_close_all_type(BLOCK_EXPORT_TYPE_NBD);
nbd_server_free(nbd_server);
nbd_server = NULL;
diff --git a/nbd/server.c b/nbd/server.c
index 6a58297557..7e2976b81d 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -100,8 +100,6 @@ struct NBDExport {
};
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
-static QTAILQ_HEAD(, NBDExport) closed_exports =
- QTAILQ_HEAD_INITIALIZER(closed_exports);
/* NBDExportMetaContexts represents a list of contexts to be exported,
* as selected by NBD_OPT_SET_META_CONTEXT. Also used for
@@ -1494,12 +1492,8 @@ static void blk_aio_detach(void *opaque)
static void nbd_eject_notifier(Notifier *n, void *data)
{
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
- AioContext *aio_context;
- aio_context = exp->common.ctx;
- aio_context_acquire(aio_context);
- nbd_export_close(exp);
- aio_context_release(aio_context);
+ blk_exp_request_shutdown(&exp->common);
}
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk)
@@ -1652,8 +1646,9 @@ nbd_export_aio_context(NBDExport *exp)
return exp->common.ctx;
}
-void nbd_export_close(NBDExport *exp)
+static void nbd_export_request_shutdown(BlockExport *blk_exp)
{
+ NBDExport *exp = container_of(blk_exp, NBDExport, common);
NBDClient *client, *next;
blk_exp_ref(&exp->common);
@@ -1672,7 +1667,6 @@ void nbd_export_close(NBDExport *exp)
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
- QTAILQ_INSERT_TAIL(&closed_exports, exp, next);
}
blk_exp_unref(&exp->common);
}
@@ -1681,7 +1675,7 @@ void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
{
ERRP_GUARD();
if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) {
- nbd_export_close(exp);
+ nbd_export_request_shutdown(&exp->common);
return;
}
@@ -1716,9 +1710,6 @@ static void nbd_export_delete(BlockExport *blk_exp)
bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false);
g_free(exp->export_bitmap_context);
}
-
- QTAILQ_REMOVE(&closed_exports, exp, next);
- aio_wait_kick();
}
const BlockExportDriver blk_exp_nbd = {
@@ -1726,24 +1717,9 @@ const BlockExportDriver blk_exp_nbd = {
.instance_size = sizeof(NBDExport),
.create = nbd_export_create,
.delete = nbd_export_delete,
+ .request_shutdown = nbd_export_request_shutdown,
};
-void nbd_export_close_all(void)
-{
- NBDExport *exp, *next;
- AioContext *aio_context;
-
- QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
- aio_context = exp->common.ctx;
- aio_context_acquire(aio_context);
- nbd_export_close(exp);
- aio_context_release(aio_context);
- }
-
- AIO_WAIT_WHILE(NULL, !(QTAILQ_EMPTY(&exports) &&
- QTAILQ_EMPTY(&closed_exports)));
-}
-
static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov,
unsigned niov, Error **errp)
{
diff --git a/qemu-nbd.c b/qemu-nbd.c
index f31868708c..939a08902a 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -1110,7 +1110,7 @@ int main(int argc, char **argv)
do {
main_loop_wait(false);
if (state == TERMINATE) {
- nbd_export_close_all();
+ blk_exp_close_all();
state = TERMINATED;
}
} while (state != TERMINATED);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 17/22] block/export: Add blk_exp_close_all(_type)
2020-08-13 16:29 ` [RFC PATCH 17/22] block/export: Add blk_exp_close_all(_type) Kevin Wolf
@ 2020-08-18 15:00 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-18 15:00 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 2052 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> This adds a function to shut down all block exports, and another one to
> shut down the block exports of a single type. The latter is used for now
> when stopping the NBD server. As soon as we implement support for
> multiple NBD servers, we'll need a per-server list of exports and it
> will be replaced by a function using that.
>
> As a side effect, the BlockExport layer has a list tracking all existing
> exports now. closed_exports loses its only user and can go away.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 8 +++++++
> include/block/nbd.h | 2 --
> block.c | 2 +-
> block/export/export.c | 52 ++++++++++++++++++++++++++++++++++++++++++
> blockdev-nbd.c | 2 +-
> nbd/server.c | 34 ++++-----------------------
> qemu-nbd.c | 2 +-
> 7 files changed, 68 insertions(+), 34 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
> diff --git a/block/export/export.c b/block/export/export.c
> index 9de108cbc1..675db9a8b9 100644
> --- a/block/export/export.c
> +++ b/block/export/export.c
[...]
> +/* type == BLOCK_EXPORT_TYPE__MAX for all types */
> +void blk_exp_close_all_type(BlockExportType type)
> +{
> + BlockExport *exp, *next;
> +
> + QLIST_FOREACH_SAFE(exp, &block_exports, next, next) {
> + if (type != BLOCK_EXPORT_TYPE__MAX && exp->drv->type != type) {
> + continue;
> + }
> + blk_exp_request_shutdown(exp);
> + }
> +
> + AIO_WAIT_WHILE(NULL, blk_exp_has_type(type));
> +}
> +
> +void blk_exp_close_all(void)
> +{
> + blk_exp_close_all_type(BLOCK_EXPORT_TYPE__MAX);
What’s interesting about this is that I saw from the header file that
you added both this and the type-specific function and wondered “Why not
just pass __MAX to close_all_type() to close all?” And then I thought
“Because that would be stupid as an external interface”.
So I see you had the same thinking.
[-- Attachment #2: OpenPGP digital signature --]
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^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 18/22] block/export: Add 'id' option to block-export-add
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (16 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 17/22] block/export: Add blk_exp_close_all(_type) Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-18 15:08 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 19/22] block/export: Move strong user reference to block_exports Kevin Wolf
` (3 subsequent siblings)
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
We'll need an id to identify block exports in monitor commands. This
adds one.
Note that this is different from the 'name' option in the NBD server,
which is the externally visible export name. While block export ids need
to be unique in the whole process, export names must be unique only for
the same server. Different export types or (potentially in the future)
multiple NBD servers can have the same export name externally, but still
need different block export ids internally.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 3 +++
include/block/export.h | 3 +++
block/export/export.c | 27 +++++++++++++++++++++++++++
qemu-nbd.c | 1 +
4 files changed, 34 insertions(+)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index d68f3bf87e..0d0db9ca1b 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -179,6 +179,8 @@
# Describes a block export, i.e. how single node should be exported on an
# external interface.
#
+# @id: A unique identifier for the block export (across all export types)
+#
# @device: The device name or node name of the node to be exported
#
# @writethrough: If true, caches are flushed after every write request to the
@@ -189,6 +191,7 @@
##
{ 'union': 'BlockExportOptions',
'base': { 'type': 'BlockExportType',
+ 'id': 'str',
'device': 'str',
'*writethrough': 'bool' },
'discriminator': 'type',
diff --git a/include/block/export.h b/include/block/export.h
index 1698b68f09..43229857b0 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -30,6 +30,9 @@ typedef struct BlockExportDriver {
struct BlockExport {
const BlockExportDriver *drv;
+ /* Unique identifier for the export */
+ char *id;
+
/*
* Reference count for this block export. This includes strong references
* both from the owner (qemu-nbd or the monitor) and clients connected to
diff --git a/block/export/export.c b/block/export/export.c
index 675db9a8b9..72f1fab975 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -19,6 +19,7 @@
#include "block/nbd.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-block-export.h"
+#include "qemu/id.h"
static const BlockExportDriver* blk_exp_drivers[] = {
&blk_exp_nbd,
@@ -27,6 +28,19 @@ static const BlockExportDriver* blk_exp_drivers[] = {
static QLIST_HEAD(, BlockExport) block_exports =
QLIST_HEAD_INITIALIZER(block_exports);
+static BlockExport *blk_exp_find(const char *id)
+{
+ BlockExport *exp;
+
+ QLIST_FOREACH(exp, &block_exports, next) {
+ if (strcmp(id, exp->id) == 0) {
+ return exp;
+ }
+ }
+
+ return NULL;
+}
+
static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
{
int i;
@@ -45,6 +59,15 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
BlockExport *exp;
int ret;
+ if (!id_wellformed(export->id)) {
+ error_setg(errp, "Invalid block export id");
+ return NULL;
+ }
+ if (blk_exp_find(export->id)) {
+ error_setg(errp, "Block export id '%s' is already in use", export->id);
+ return NULL;
+ }
+
drv = blk_exp_find_driver(export->type);
if (!drv) {
error_setg(errp, "No driver found for the requested export type");
@@ -55,10 +78,12 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
*exp = (BlockExport) {
.drv = &blk_exp_nbd,
.refcount = 1,
+ .id = g_strdup(export->id),
};
ret = drv->create(exp, export, errp);
if (ret < 0) {
+ g_free(exp->id);
g_free(exp);
return NULL;
}
@@ -79,6 +104,7 @@ void blk_exp_unref(BlockExport *exp)
if (--exp->refcount == 0) {
QLIST_REMOVE(exp, next);
exp->drv->delete(exp);
+ g_free(exp->id);
g_free(exp);
aio_wait_kick();
}
@@ -144,6 +170,7 @@ void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
BlockExportOptions *export_opts = g_new(BlockExportOptions, 1);
*export_opts = (BlockExportOptions) {
.type = BLOCK_EXPORT_TYPE_NBD,
+ .id = g_strdup(arg->name ?: arg->device),
.device = g_strdup(arg->device),
.u.nbd = {
.has_name = arg->has_name,
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 939a08902a..c6fc0581c1 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -1055,6 +1055,7 @@ int main(int argc, char **argv)
export_opts = g_new(BlockExportOptions, 1);
*export_opts = (BlockExportOptions) {
.type = BLOCK_EXPORT_TYPE_NBD,
+ .id = g_strdup("qemu-nbd-export"),
.device = g_strdup(bdrv_get_node_name(bs)),
.has_writethrough = true,
.writethrough = writethrough,
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 18/22] block/export: Add 'id' option to block-export-add
2020-08-13 16:29 ` [RFC PATCH 18/22] block/export: Add 'id' option to block-export-add Kevin Wolf
@ 2020-08-18 15:08 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-18 15:08 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1563 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> We'll need an id to identify block exports in monitor commands. This
> adds one.
>
> Note that this is different from the 'name' option in the NBD server,
> which is the externally visible export name. While block export ids need
> to be unique in the whole process, export names must be unique only for
> the same server. Different export types or (potentially in the future)
> multiple NBD servers can have the same export name externally, but still
> need different block export ids internally.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 3 +++
> include/block/export.h | 3 +++
> block/export/export.c | 27 +++++++++++++++++++++++++++
> qemu-nbd.c | 1 +
> 4 files changed, 34 insertions(+)
Looks good, just one thing:
> diff --git a/block/export/export.c b/block/export/export.c
> index 675db9a8b9..72f1fab975 100644
> --- a/block/export/export.c
> +++ b/block/export/export.c
[...]
> @@ -144,6 +170,7 @@ void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
> BlockExportOptions *export_opts = g_new(BlockExportOptions, 1);
> *export_opts = (BlockExportOptions) {
> .type = BLOCK_EXPORT_TYPE_NBD,
> + .id = g_strdup(arg->name ?: arg->device),
Maybe this behavior should be documented for nbd-server-add?
> .device = g_strdup(arg->device),
> .u.nbd = {
> .has_name = arg->has_name,
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 19/22] block/export: Move strong user reference to block_exports
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (17 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 18/22] block/export: Add 'id' option to block-export-add Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-19 8:35 ` Max Reitz
2020-08-19 11:56 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 20/22] block/export: Add block-export-del Kevin Wolf
` (2 subsequent siblings)
21 siblings, 2 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
The reference owned by the user/monitor that is created when adding the
export and dropped when removing it was tied to the 'exports' list in
nbd/server.c. Every block export will have a user reference, so move it
to the block export level and tie it to the 'block_exports' list in
block/export/export.c instead. This is necessary for introducing a QMP
command for removing exports.
Note that exports are present in block_exports even after the user has
requested shutdown. This is different from NBD's exports where exports
are immediately removed on a shutdown request, even if they are still in
the process of shutting down. In order to avoid that the user still
interacts with an export that is shutting down (and possibly removes it
a second time), we need to remember if the user actually still owns it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 8 ++++++++
block/export/export.c | 4 ++++
blockdev-nbd.c | 5 -----
nbd/server.c | 2 --
4 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index 43229857b0..83f554b745 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -40,6 +40,14 @@ struct BlockExport {
*/
int refcount;
+ /*
+ * True if one of the references in refcount belongs to the user. After the
+ * user has dropped their reference, they may not e.g. remove the same
+ * export a second time (which would decrease the refcount without having
+ * it incremented first).
+ */
+ bool user_owned;
+
/*
* The AioContex whose lock needs to be held while calling
* BlockExportDriver callbacks.
diff --git a/block/export/export.c b/block/export/export.c
index 72f1fab975..f94a81258a 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -78,6 +78,7 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
*exp = (BlockExport) {
.drv = &blk_exp_nbd,
.refcount = 1,
+ .user_owned = true,
.id = g_strdup(export->id),
};
@@ -117,6 +118,9 @@ void blk_exp_request_shutdown(BlockExport *exp)
aio_context_acquire(aio_context);
exp->drv->request_shutdown(exp);
aio_context_release(aio_context);
+
+ exp->user_owned = false;
+ blk_exp_unref(exp);
}
static bool blk_exp_has_type(BlockExportType type)
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 1c7aa874ee..40013b7d64 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -231,11 +231,6 @@ int nbd_export_create(BlockExport *exp, BlockExportOptions *exp_args,
goto out;
}
- /* The list of named exports has a strong reference to this export now and
- * our only way of accessing it is through nbd_export_find(), so we can drop
- * the strong reference that is @exp. */
- blk_exp_unref((BlockExport*) exp);
-
ret = 0;
out:
aio_context_release(aio_context);
diff --git a/nbd/server.c b/nbd/server.c
index 7e2976b81d..e3ac7f548b 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1616,7 +1616,6 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
- blk_exp_ref(&exp->common);
QTAILQ_INSERT_TAIL(&exports, exp, next);
return 0;
@@ -1663,7 +1662,6 @@ static void nbd_export_request_shutdown(BlockExport *blk_exp)
client_close(client, true);
}
if (exp->name) {
- blk_exp_unref(&exp->common);
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 19/22] block/export: Move strong user reference to block_exports
2020-08-13 16:29 ` [RFC PATCH 19/22] block/export: Move strong user reference to block_exports Kevin Wolf
@ 2020-08-19 8:35 ` Max Reitz
2020-08-19 11:56 ` Max Reitz
1 sibling, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-19 8:35 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1196 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> The reference owned by the user/monitor that is created when adding the
> export and dropped when removing it was tied to the 'exports' list in
> nbd/server.c. Every block export will have a user reference, so move it
> to the block export level and tie it to the 'block_exports' list in
> block/export/export.c instead. This is necessary for introducing a QMP
> command for removing exports.
>
> Note that exports are present in block_exports even after the user has
> requested shutdown. This is different from NBD's exports where exports
> are immediately removed on a shutdown request, even if they are still in
> the process of shutting down. In order to avoid that the user still
> interacts with an export that is shutting down (and possibly removes it
> a second time), we need to remember if the user actually still owns it.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 8 ++++++++
> block/export/export.c | 4 ++++
> blockdev-nbd.c | 5 -----
> nbd/server.c | 2 --
> 4 files changed, 12 insertions(+), 7 deletions(-)
Reviewed-by: Max Reitz <mreitz@redhat.com>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 19/22] block/export: Move strong user reference to block_exports
2020-08-13 16:29 ` [RFC PATCH 19/22] block/export: Move strong user reference to block_exports Kevin Wolf
2020-08-19 8:35 ` Max Reitz
@ 2020-08-19 11:56 ` Max Reitz
2020-08-19 14:23 ` Kevin Wolf
1 sibling, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-19 11:56 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
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On 13.08.20 18:29, Kevin Wolf wrote:
> The reference owned by the user/monitor that is created when adding the
> export and dropped when removing it was tied to the 'exports' list in
> nbd/server.c. Every block export will have a user reference, so move it
> to the block export level and tie it to the 'block_exports' list in
> block/export/export.c instead. This is necessary for introducing a QMP
> command for removing exports.
>
> Note that exports are present in block_exports even after the user has
> requested shutdown. This is different from NBD's exports where exports
> are immediately removed on a shutdown request, even if they are still in
> the process of shutting down. In order to avoid that the user still
> interacts with an export that is shutting down (and possibly removes it
> a second time), we need to remember if the user actually still owns it.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> include/block/export.h | 8 ++++++++
> block/export/export.c | 4 ++++
> blockdev-nbd.c | 5 -----
> nbd/server.c | 2 --
> 4 files changed, 12 insertions(+), 7 deletions(-)
With this patch, there’s an abort in iotest 281. Perhaps because
blk_exp_unref() is now done by blk_exp_request_shutdown() outside of
where the AIO context is locked?
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* Re: [RFC PATCH 19/22] block/export: Move strong user reference to block_exports
2020-08-19 11:56 ` Max Reitz
@ 2020-08-19 14:23 ` Kevin Wolf
2020-08-19 14:48 ` Max Reitz
0 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-19 14:23 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
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Am 19.08.2020 um 13:56 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > The reference owned by the user/monitor that is created when adding the
> > export and dropped when removing it was tied to the 'exports' list in
> > nbd/server.c. Every block export will have a user reference, so move it
> > to the block export level and tie it to the 'block_exports' list in
> > block/export/export.c instead. This is necessary for introducing a QMP
> > command for removing exports.
> >
> > Note that exports are present in block_exports even after the user has
> > requested shutdown. This is different from NBD's exports where exports
> > are immediately removed on a shutdown request, even if they are still in
> > the process of shutting down. In order to avoid that the user still
> > interacts with an export that is shutting down (and possibly removes it
> > a second time), we need to remember if the user actually still owns it.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > include/block/export.h | 8 ++++++++
> > block/export/export.c | 4 ++++
> > blockdev-nbd.c | 5 -----
> > nbd/server.c | 2 --
> > 4 files changed, 12 insertions(+), 7 deletions(-)
>
> With this patch, there’s an abort in iotest 281. Perhaps because
> blk_exp_unref() is now done by blk_exp_request_shutdown() outside of
> where the AIO context is locked?
I have two fixes locally that were related to failing qemu-iotests. I
guess the first one might be for what you're seeing?
Kevin
diff --git a/block/export/export.c b/block/export/export.c
index 71d17bd440..d021b98b74 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -105,9 +105,14 @@ void blk_exp_unref(BlockExport *exp)
{
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
+ AioContext *aio_context = exp->ctx;
+
+ aio_context_acquire(aio_context);
QLIST_REMOVE(exp, next);
exp->drv->delete(exp);
blk_unref(exp->blk);
+ aio_context_release(aio_context);
+
g_free(exp->id);
g_free(exp);
aio_wait_kick();
diff --git a/tests/qemu-iotests/223.out b/tests/qemu-iotests/223.out
index e1eaaedb55..31ce9e6fe0 100644
--- a/tests/qemu-iotests/223.out
+++ b/tests/qemu-iotests/223.out
@@ -45,7 +45,7 @@ exports available: 0
{"execute":"nbd-server-add", "arguments":{"device":"nosuch"}}
{"error": {"class": "GenericError", "desc": "Cannot find device=nosuch nor node_name=nosuch"}}
{"execute":"nbd-server-add", "arguments":{"device":"n"}}
-{"error": {"class": "GenericError", "desc": "NBD server already has export named 'n'"}}
+{"error": {"class": "GenericError", "desc": "Block export id 'n' is already in use"}}
{"execute":"nbd-server-add", "arguments":{"device":"n", "name":"n2", "bitmap":"b2"}}
{"error": {"class": "GenericError", "desc": "Enabled bitmap 'b2' incompatible with readonly export"}}
{"execute":"nbd-server-add", "arguments":{"device":"n", "name":"n2", "bitmap":"b3"}}
@@ -126,7 +126,7 @@ exports available: 0
{"execute":"nbd-server-add", "arguments":{"device":"nosuch"}}
{"error": {"class": "GenericError", "desc": "Cannot find device=nosuch nor node_name=nosuch"}}
{"execute":"nbd-server-add", "arguments":{"device":"n"}}
-{"error": {"class": "GenericError", "desc": "NBD server already has export named 'n'"}}
+{"error": {"class": "GenericError", "desc": "Block export id 'n' is already in use"}}
{"execute":"nbd-server-add", "arguments":{"device":"n", "name":"n2", "bitmap":"b2"}}
{"error": {"class": "GenericError", "desc": "Enabled bitmap 'b2' incompatible with readonly export"}}
{"execute":"nbd-server-add", "arguments":{"device":"n", "name":"n2", "bitmap":"b3"}}
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^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 19/22] block/export: Move strong user reference to block_exports
2020-08-19 14:23 ` Kevin Wolf
@ 2020-08-19 14:48 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-19 14:48 UTC (permalink / raw)
To: Kevin Wolf; +Cc: qemu-devel, qemu-block
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On 19.08.20 16:23, Kevin Wolf wrote:
> Am 19.08.2020 um 13:56 hat Max Reitz geschrieben:
>> On 13.08.20 18:29, Kevin Wolf wrote:
>>> The reference owned by the user/monitor that is created when adding the
>>> export and dropped when removing it was tied to the 'exports' list in
>>> nbd/server.c. Every block export will have a user reference, so move it
>>> to the block export level and tie it to the 'block_exports' list in
>>> block/export/export.c instead. This is necessary for introducing a QMP
>>> command for removing exports.
>>>
>>> Note that exports are present in block_exports even after the user has
>>> requested shutdown. This is different from NBD's exports where exports
>>> are immediately removed on a shutdown request, even if they are still in
>>> the process of shutting down. In order to avoid that the user still
>>> interacts with an export that is shutting down (and possibly removes it
>>> a second time), we need to remember if the user actually still owns it.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>> include/block/export.h | 8 ++++++++
>>> block/export/export.c | 4 ++++
>>> blockdev-nbd.c | 5 -----
>>> nbd/server.c | 2 --
>>> 4 files changed, 12 insertions(+), 7 deletions(-)
>>
>> With this patch, there’s an abort in iotest 281. Perhaps because
>> blk_exp_unref() is now done by blk_exp_request_shutdown() outside of
>> where the AIO context is locked?
>
> I have two fixes locally that were related to failing qemu-iotests. I
> guess the first one might be for what you're seeing?
>
> Kevin
>
> diff --git a/block/export/export.c b/block/export/export.c
> index 71d17bd440..d021b98b74 100644
> --- a/block/export/export.c
> +++ b/block/export/export.c
> @@ -105,9 +105,14 @@ void blk_exp_unref(BlockExport *exp)
> {
> assert(exp->refcount > 0);
> if (--exp->refcount == 0) {
If this is done without locking the context, should this be an atomic
operation?
> + AioContext *aio_context = exp->ctx;
> +
> + aio_context_acquire(aio_context);
> QLIST_REMOVE(exp, next);
> exp->drv->delete(exp);
> blk_unref(exp->blk);
> + aio_context_release(aio_context);
> +
But for the crash I was seeing, this should be sufficient, yes.
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 20/22] block/export: Add block-export-del
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (18 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 19/22] block/export: Move strong user reference to block_exports Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-19 9:54 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 21/22] block/export: Move blk to BlockExport Kevin Wolf
2020-08-13 16:29 ` [RFC PATCH 22/22] block/export: Add query-block-exports Kevin Wolf
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Implement a new QMP command block-export-del and make nbd-server-remove
a wrapper around it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 30 +++++++++++++++----
include/block/nbd.h | 1 -
block/export/export.c | 54 ++++++++++++++++++++++++++++++++++
block/monitor/block-hmp-cmds.c | 2 +-
blockdev-nbd.c | 28 ------------------
nbd/server.c | 14 ---------
6 files changed, 79 insertions(+), 50 deletions(-)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 0d0db9ca1b..a067de2ba3 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -111,9 +111,9 @@
'data': 'NbdServerAddOptions', 'boxed': true }
##
-# @NbdServerRemoveMode:
+# @BlockExportRemoveMode:
#
-# Mode for removing an NBD export.
+# Mode for removing a block export.
#
# @safe: Remove export if there are no existing connections, fail otherwise.
#
@@ -129,16 +129,16 @@
#
# Since: 2.12
##
-{'enum': 'NbdServerRemoveMode', 'data': ['safe', 'hard']}
+{'enum': 'BlockExportRemoveMode', 'data': ['safe', 'hard']}
##
# @nbd-server-remove:
#
# Remove NBD export by name.
#
-# @name: Export name.
+# @name: Block export id.
#
-# @mode: Mode of command operation. See @NbdServerRemoveMode description.
+# @mode: Mode of command operation. See @BlockExportRemoveMode description.
# Default is 'safe'.
#
# Returns: error if
@@ -149,7 +149,7 @@
# Since: 2.12
##
{ 'command': 'nbd-server-remove',
- 'data': {'name': 'str', '*mode': 'NbdServerRemoveMode'} }
+ 'data': {'name': 'str', '*mode': 'BlockExportRemoveMode'} }
##
# @nbd-server-stop:
@@ -208,3 +208,21 @@
##
{ 'command': 'block-export-add',
'data': 'BlockExportOptions', 'boxed': true }
+
+##
+# @block-export-del:
+#
+# Remove a block export.
+#
+# @id: Block export id.
+#
+# @mode: Mode of command operation. See @BlockExportRemoveMode description.
+# Default is 'safe'.
+#
+# Returns: Error if the export is not found or @mode is 'safe' and the export
+# is still in use (e.g. by existing client connections)
+#
+# Since: 5.2
+##
+{ 'command': 'block-export-del',
+ 'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 91a9d4f96d..7982a63f96 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -335,7 +335,6 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
const char *bitmap, bool readonly, bool shared,
bool writethrough, Error **errp);
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
-void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
AioContext *nbd_export_aio_context(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);
diff --git a/block/export/export.c b/block/export/export.c
index f94a81258a..1255f3fc80 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -115,6 +115,15 @@ void blk_exp_request_shutdown(BlockExport *exp)
{
AioContext *aio_context = exp->ctx;
+ /*
+ * If the user doesn't own the export any more, it is already shutting
+ * down. We must not call .request_shutdown and decrease the refcount a
+ * second time.
+ */
+ if (!exp->user_owned) {
+ return;
+ }
+
aio_context_acquire(aio_context);
exp->drv->request_shutdown(exp);
aio_context_release(aio_context);
@@ -215,3 +224,48 @@ void qmp_nbd_server_add(NbdServerAddOptions *arg, Error **errp)
fail:
qapi_free_BlockExportOptions(export_opts);
}
+
+void qmp_block_export_del(const char *id,
+ bool has_mode, BlockExportRemoveMode mode,
+ Error **errp)
+{
+ ERRP_GUARD();
+ BlockExport *exp;
+
+ exp = blk_exp_find(id);
+ if (exp == NULL) {
+ error_setg(errp, "Export '%s' is not found", id);
+ return;
+ }
+ if (!exp->user_owned) {
+ error_setg(errp, "Export '%s' is already shutting down", id);
+ return;
+ }
+
+ if (!has_mode) {
+ mode = BLOCK_EXPORT_REMOVE_MODE_SAFE;
+ }
+ if (mode == BLOCK_EXPORT_REMOVE_MODE_SAFE && exp->refcount > 1) {
+ error_setg(errp, "export '%s' still in use", exp->id);
+ error_append_hint(errp, "Use mode='hard' to force client "
+ "disconnect\n");
+ return;
+ }
+
+ blk_exp_request_shutdown(exp);
+}
+
+void qmp_nbd_server_remove(const char *name,
+ bool has_mode, BlockExportRemoveMode mode,
+ Error **errp)
+{
+ BlockExport *exp;
+
+ exp = blk_exp_find(name);
+ if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) {
+ error_setg(errp, "Block export '%s' is not an NBD export", name);
+ return;
+ }
+
+ qmp_block_export_del(name, has_mode, mode, errp);
+}
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index 6c823234a9..10165252cf 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -477,7 +477,7 @@ void hmp_nbd_server_remove(Monitor *mon, const QDict *qdict)
Error *err = NULL;
/* Rely on NBD_SERVER_REMOVE_MODE_SAFE being the default */
- qmp_nbd_server_remove(name, force, NBD_SERVER_REMOVE_MODE_HARD, &err);
+ qmp_nbd_server_remove(name, force, BLOCK_EXPORT_REMOVE_MODE_HARD, &err);
hmp_handle_error(mon, err);
}
diff --git a/blockdev-nbd.c b/blockdev-nbd.c
index 40013b7d64..5ec21045a8 100644
--- a/blockdev-nbd.c
+++ b/blockdev-nbd.c
@@ -237,34 +237,6 @@ int nbd_export_create(BlockExport *exp, BlockExportOptions *exp_args,
return ret;
}
-void qmp_nbd_server_remove(const char *name,
- bool has_mode, NbdServerRemoveMode mode,
- Error **errp)
-{
- NBDExport *exp;
- AioContext *aio_context;
-
- if (!nbd_server) {
- error_setg(errp, "NBD server not running");
- return;
- }
-
- exp = nbd_export_find(name);
- if (exp == NULL) {
- error_setg(errp, "Export '%s' is not found", name);
- return;
- }
-
- if (!has_mode) {
- mode = NBD_SERVER_REMOVE_MODE_SAFE;
- }
-
- aio_context = nbd_export_aio_context(exp);
- aio_context_acquire(aio_context);
- nbd_export_remove(exp, mode, errp);
- aio_context_release(aio_context);
-}
-
void qmp_nbd_server_stop(Error **errp)
{
if (!nbd_server) {
diff --git a/nbd/server.c b/nbd/server.c
index e3ac7f548b..899d00782f 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1669,20 +1669,6 @@ static void nbd_export_request_shutdown(BlockExport *blk_exp)
blk_exp_unref(&exp->common);
}
-void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
-{
- ERRP_GUARD();
- if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) {
- nbd_export_request_shutdown(&exp->common);
- return;
- }
-
- assert(mode == NBD_SERVER_REMOVE_MODE_SAFE);
-
- error_setg(errp, "export '%s' still in use", exp->name);
- error_append_hint(errp, "Use mode='hard' to force client disconnect\n");
-}
-
static void nbd_export_delete(BlockExport *blk_exp)
{
NBDExport *exp = container_of(blk_exp, NBDExport, common);
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 20/22] block/export: Add block-export-del
2020-08-13 16:29 ` [RFC PATCH 20/22] block/export: Add block-export-del Kevin Wolf
@ 2020-08-19 9:54 ` Max Reitz
0 siblings, 0 replies; 90+ messages in thread
From: Max Reitz @ 2020-08-19 9:54 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1284 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> Implement a new QMP command block-export-del and make nbd-server-remove
> a wrapper around it.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 30 +++++++++++++++----
> include/block/nbd.h | 1 -
> block/export/export.c | 54 ++++++++++++++++++++++++++++++++++
> block/monitor/block-hmp-cmds.c | 2 +-
> blockdev-nbd.c | 28 ------------------
> nbd/server.c | 14 ---------
> 6 files changed, 79 insertions(+), 50 deletions(-)
[...]
> diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
> index 6c823234a9..10165252cf 100644
> --- a/block/monitor/block-hmp-cmds.c
> +++ b/block/monitor/block-hmp-cmds.c
> @@ -477,7 +477,7 @@ void hmp_nbd_server_remove(Monitor *mon, const QDict *qdict)
> Error *err = NULL;
>
> /* Rely on NBD_SERVER_REMOVE_MODE_SAFE being the default */
This comment needs adjustment, too.
With that done:
Reviewed-by: Max Reitz <mreitz@redhat.com>
> - qmp_nbd_server_remove(name, force, NBD_SERVER_REMOVE_MODE_HARD, &err);
> + qmp_nbd_server_remove(name, force, BLOCK_EXPORT_REMOVE_MODE_HARD, &err);
> hmp_handle_error(mon, err);
> }
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^ permalink raw reply [flat|nested] 90+ messages in thread
* [RFC PATCH 21/22] block/export: Move blk to BlockExport
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (19 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 20/22] block/export: Add block-export-del Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-19 10:53 ` Max Reitz
2020-08-13 16:29 ` [RFC PATCH 22/22] block/export: Add query-block-exports Kevin Wolf
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
Every block export has a BlockBackend representing the disk that is
exported. It should live in BlockExport therefore.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/export.h | 3 +++
block/export/export.c | 3 +++
nbd/server.c | 44 ++++++++++++++++++++++--------------------
3 files changed, 29 insertions(+), 21 deletions(-)
diff --git a/include/block/export.h b/include/block/export.h
index 83f554b745..53b4163a3b 100644
--- a/include/block/export.h
+++ b/include/block/export.h
@@ -54,6 +54,9 @@ struct BlockExport {
*/
AioContext *ctx;
+ /* The block device to export */
+ BlockBackend *blk;
+
/* List entry for block_exports */
QLIST_ENTRY(BlockExport) next;
};
diff --git a/block/export/export.c b/block/export/export.c
index 1255f3fc80..3cd448ba72 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -89,6 +89,8 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return NULL;
}
+ assert(exp->blk != NULL);
+
QLIST_INSERT_HEAD(&block_exports, exp, next);
return exp;
}
@@ -105,6 +107,7 @@ void blk_exp_unref(BlockExport *exp)
if (--exp->refcount == 0) {
QLIST_REMOVE(exp, next);
exp->drv->delete(exp);
+ blk_unref(exp->blk);
g_free(exp->id);
g_free(exp);
aio_wait_kick();
diff --git a/nbd/server.c b/nbd/server.c
index 899d00782f..6ad78203c9 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -84,7 +84,6 @@ struct NBDRequestData {
struct NBDExport {
BlockExport common;
- BlockBackend *blk;
char *name;
char *description;
uint64_t size;
@@ -643,7 +642,7 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
* whether this is OPT_INFO or OPT_GO. */
/* minimum - 1 for back-compat, or actual if client will obey it. */
if (client->opt == NBD_OPT_INFO || blocksize) {
- check_align = sizes[0] = blk_get_request_alignment(exp->blk);
+ check_align = sizes[0] = blk_get_request_alignment(exp->common.blk);
} else {
sizes[0] = 1;
}
@@ -652,7 +651,7 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
* TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */
sizes[1] = MAX(4096, sizes[0]);
/* maximum - At most 32M, but smaller as appropriate. */
- sizes[2] = MIN(blk_get_max_transfer(exp->blk), NBD_MAX_BUFFER_SIZE);
+ sizes[2] = MIN(blk_get_max_transfer(exp->common.blk), NBD_MAX_BUFFER_SIZE);
trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]);
sizes[0] = cpu_to_be32(sizes[0]);
sizes[1] = cpu_to_be32(sizes[1]);
@@ -684,7 +683,7 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
* tolerate all clients, regardless of alignments.
*/
if (client->opt == NBD_OPT_INFO && !blocksize &&
- blk_get_request_alignment(exp->blk) > 1) {
+ blk_get_request_alignment(exp->common.blk) > 1) {
return nbd_negotiate_send_rep_err(client,
NBD_REP_ERR_BLOCK_SIZE_REQD,
errp,
@@ -1556,7 +1555,7 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs,
blk_set_allow_aio_context_change(blk, true);
QTAILQ_INIT(&exp->clients);
- exp->blk = blk;
+ exp->common.blk = blk;
exp->name = g_strdup(name);
assert(!desc || strlen(desc) <= NBD_MAX_STRING_SIZE);
exp->description = g_strdup(desc);
@@ -1679,15 +1678,13 @@ static void nbd_export_delete(BlockExport *blk_exp)
g_free(exp->description);
exp->description = NULL;
- if (exp->blk) {
+ if (exp->common.blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
- blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
+ blk_remove_aio_context_notifier(exp->common.blk, blk_aio_attached,
blk_aio_detach, exp);
- blk_unref(exp->blk);
- exp->blk = NULL;
}
if (exp->export_bitmap) {
@@ -1840,7 +1837,7 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client,
while (progress < size) {
int64_t pnum;
- int status = bdrv_block_status_above(blk_bs(exp->blk), NULL,
+ int status = bdrv_block_status_above(blk_bs(exp->common.blk), NULL,
offset + progress,
size - progress, &pnum, NULL,
NULL);
@@ -1872,7 +1869,8 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client,
stl_be_p(&chunk.length, pnum);
ret = nbd_co_send_iov(client, iov, 1, errp);
} else {
- ret = blk_pread(exp->blk, offset + progress, data + progress, pnum);
+ ret = blk_pread(exp->common.blk, offset + progress,
+ data + progress, pnum);
if (ret < 0) {
error_setg_errno(errp, -ret, "reading from file failed");
break;
@@ -2136,7 +2134,8 @@ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
}
if (request->type != NBD_CMD_CACHE) {
- req->data = blk_try_blockalign(client->exp->blk, request->len);
+ req->data = blk_try_blockalign(client->exp->common.blk,
+ request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
@@ -2232,7 +2231,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request,
/* XXX: NBD Protocol only documents use of FUA with WRITE */
if (request->flags & NBD_CMD_FLAG_FUA) {
- ret = blk_co_flush(exp->blk);
+ ret = blk_co_flush(exp->common.blk);
if (ret < 0) {
return nbd_send_generic_reply(client, request->handle, ret,
"flush failed", errp);
@@ -2246,7 +2245,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request,
data, request->len, errp);
}
- ret = blk_pread(exp->blk, request->from, data, request->len);
+ ret = blk_pread(exp->common.blk, request->from, data, request->len);
if (ret < 0) {
return nbd_send_generic_reply(client, request->handle, ret,
"reading from file failed", errp);
@@ -2281,7 +2280,7 @@ static coroutine_fn int nbd_do_cmd_cache(NBDClient *client, NBDRequest *request,
assert(request->type == NBD_CMD_CACHE);
- ret = blk_co_preadv(exp->blk, request->from, request->len,
+ ret = blk_co_preadv(exp->common.blk, request->from, request->len,
NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
return nbd_send_generic_reply(client, request->handle, ret,
@@ -2312,7 +2311,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
if (request->flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
- ret = blk_pwrite(exp->blk, request->from, data, request->len, flags);
+ ret = blk_pwrite(exp->common.blk, request->from, data, request->len,
+ flags);
return nbd_send_generic_reply(client, request->handle, ret,
"writing to file failed", errp);
@@ -2327,7 +2327,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
if (request->flags & NBD_CMD_FLAG_FAST_ZERO) {
flags |= BDRV_REQ_NO_FALLBACK;
}
- ret = blk_pwrite_zeroes(exp->blk, request->from, request->len, flags);
+ ret = blk_pwrite_zeroes(exp->common.blk, request->from, request->len,
+ flags);
return nbd_send_generic_reply(client, request->handle, ret,
"writing to file failed", errp);
@@ -2336,14 +2337,14 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
abort();
case NBD_CMD_FLUSH:
- ret = blk_co_flush(exp->blk);
+ ret = blk_co_flush(exp->common.blk);
return nbd_send_generic_reply(client, request->handle, ret,
"flush failed", errp);
case NBD_CMD_TRIM:
- ret = blk_co_pdiscard(exp->blk, request->from, request->len);
+ ret = blk_co_pdiscard(exp->common.blk, request->from, request->len);
if (ret == 0 && request->flags & NBD_CMD_FLAG_FUA) {
- ret = blk_co_flush(exp->blk);
+ ret = blk_co_flush(exp->common.blk);
}
return nbd_send_generic_reply(client, request->handle, ret,
"discard failed", errp);
@@ -2361,7 +2362,8 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
if (client->export_meta.base_allocation) {
ret = nbd_co_send_block_status(client, request->handle,
- blk_bs(exp->blk), request->from,
+ blk_bs(exp->common.blk),
+ request->from,
request->len, dont_fragment,
!client->export_meta.bitmap,
NBD_META_ID_BASE_ALLOCATION,
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* [RFC PATCH 22/22] block/export: Add query-block-exports
2020-08-13 16:29 [RFC PATCH 00/22] block/export: Add infrastructure and QAPI for block exports Kevin Wolf
` (20 preceding siblings ...)
2020-08-13 16:29 ` [RFC PATCH 21/22] block/export: Move blk to BlockExport Kevin Wolf
@ 2020-08-13 16:29 ` Kevin Wolf
2020-08-19 11:04 ` Max Reitz
21 siblings, 1 reply; 90+ messages in thread
From: Kevin Wolf @ 2020-08-13 16:29 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, qemu-devel, mreitz
This adds a simple QMP command to query the list of block exports.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qapi/block-export.json | 33 +++++++++++++++++++++++++++++++++
block/export/export.c | 23 +++++++++++++++++++++++
2 files changed, 56 insertions(+)
diff --git a/qapi/block-export.json b/qapi/block-export.json
index a067de2ba3..0b184bbd7c 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -226,3 +226,36 @@
##
{ 'command': 'block-export-del',
'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }
+
+##
+# @BlockExportInfo:
+#
+# Information about a single block export.
+#
+# @id: The unique identifier for the block export
+#
+# @type: This field is returned only for compatibility reasons, it should
+# not be used (always returns 'unknown')
+#
+# @node-name: The node name of the block node that is exported
+#
+# @shutting-down: True if the export is shutting down (e.g. after a
+# block-export-del command, but before the shutdown has
+# completed)
+#
+# Since: 5.2
+##
+{ 'struct': 'BlockExportInfo',
+ 'data': { 'id': 'str',
+ 'type': 'BlockExportType',
+ 'node-name': 'str',
+ 'shutting-down': 'bool' } }
+
+##
+# @query-block-exports:
+#
+# Returns: A list of BlockExportInfo describing all block exports
+#
+# Since: 5.2
+##
+{ 'command': 'query-block-exports', 'returns': ['BlockExportInfo'] }
diff --git a/block/export/export.c b/block/export/export.c
index 3cd448ba72..71d17bd440 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -272,3 +272,26 @@ void qmp_nbd_server_remove(const char *name,
qmp_block_export_del(name, has_mode, mode, errp);
}
+
+BlockExportInfoList *qmp_query_block_exports(Error **errp)
+{
+ BlockExportInfoList *head = NULL, **p_next = &head;
+ BlockExport *exp;
+
+ QLIST_FOREACH(exp, &block_exports, next) {
+ BlockExportInfoList *entry = g_new0(BlockExportInfoList, 1);
+ BlockExportInfo *info = g_new(BlockExportInfo, 1);
+ *info = (BlockExportInfo) {
+ .id = g_strdup(exp->id),
+ .type = exp->drv->type,
+ .node_name = g_strdup(bdrv_get_node_name(blk_bs(exp->blk))),
+ .shutting_down = !exp->user_owned,
+ };
+
+ entry->value = info;
+ *p_next = entry;
+ p_next = &entry->next;
+ }
+
+ return head;
+}
--
2.25.4
^ permalink raw reply related [flat|nested] 90+ messages in thread* Re: [RFC PATCH 22/22] block/export: Add query-block-exports
2020-08-13 16:29 ` [RFC PATCH 22/22] block/export: Add query-block-exports Kevin Wolf
@ 2020-08-19 11:04 ` Max Reitz
2020-08-19 12:04 ` Kevin Wolf
0 siblings, 1 reply; 90+ messages in thread
From: Max Reitz @ 2020-08-19 11:04 UTC (permalink / raw)
To: Kevin Wolf, qemu-block; +Cc: qemu-devel
[-- Attachment #1.1: Type: text/plain, Size: 1114 bytes --]
On 13.08.20 18:29, Kevin Wolf wrote:
> This adds a simple QMP command to query the list of block exports.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> qapi/block-export.json | 33 +++++++++++++++++++++++++++++++++
> block/export/export.c | 23 +++++++++++++++++++++++
> 2 files changed, 56 insertions(+)
>
> diff --git a/qapi/block-export.json b/qapi/block-export.json
> index a067de2ba3..0b184bbd7c 100644
> --- a/qapi/block-export.json
> +++ b/qapi/block-export.json
> @@ -226,3 +226,36 @@
> ##
> { 'command': 'block-export-del',
> 'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }
> +
> +##
> +# @BlockExportInfo:
> +#
> +# Information about a single block export.
> +#
> +# @id: The unique identifier for the block export
> +#
> +# @type: This field is returned only for compatibility reasons, it should
> +# not be used (always returns 'unknown')
Äh?
I don’t understand. It looks like it definitely doesn’t always return
“unknown”. Also, the “compatibility reasons” aren’t really immediately
clear to me... :?
Max
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^ permalink raw reply [flat|nested] 90+ messages in thread* Re: [RFC PATCH 22/22] block/export: Add query-block-exports
2020-08-19 11:04 ` Max Reitz
@ 2020-08-19 12:04 ` Kevin Wolf
0 siblings, 0 replies; 90+ messages in thread
From: Kevin Wolf @ 2020-08-19 12:04 UTC (permalink / raw)
To: Max Reitz; +Cc: qemu-devel, qemu-block
[-- Attachment #1: Type: text/plain, Size: 1308 bytes --]
Am 19.08.2020 um 13:04 hat Max Reitz geschrieben:
> On 13.08.20 18:29, Kevin Wolf wrote:
> > This adds a simple QMP command to query the list of block exports.
> >
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> > qapi/block-export.json | 33 +++++++++++++++++++++++++++++++++
> > block/export/export.c | 23 +++++++++++++++++++++++
> > 2 files changed, 56 insertions(+)
> >
> > diff --git a/qapi/block-export.json b/qapi/block-export.json
> > index a067de2ba3..0b184bbd7c 100644
> > --- a/qapi/block-export.json
> > +++ b/qapi/block-export.json
> > @@ -226,3 +226,36 @@
> > ##
> > { 'command': 'block-export-del',
> > 'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }
> > +
> > +##
> > +# @BlockExportInfo:
> > +#
> > +# Information about a single block export.
> > +#
> > +# @id: The unique identifier for the block export
> > +#
> > +# @type: This field is returned only for compatibility reasons, it should
> > +# not be used (always returns 'unknown')
>
> Äh?
>
> I don’t understand. It looks like it definitely doesn’t always return
> “unknown”. Also, the “compatibility reasons” aren’t really immediately
> clear to me... :?
Oops, this seems to be copied from BlockInfo and I forgot to change it...
Kevin
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^ permalink raw reply [flat|nested] 90+ messages in thread