[Qemu-devel] [PATCH 0/2] block/snapshot: Restrict set of snapshot nodes

[Qemu-devel] [PATCH 0/2] block/snapshot: Restrict set of snapshot nodes

[Kevin Wolf]

This fixes internal snapshots with separately defined protocol nodes
(like libvirt will do with -blockdev).

Kevin Wolf (2):
  block/snapshot: Restrict set of snapshot nodes
  iotests: Test internal snapshots with -blockdev

 block/snapshot.c                 |  26 +++--
 tests/qemu-iotests/267           | 165 ++++++++++++++++++++++++++++
 tests/qemu-iotests/267.out       | 182 +++++++++++++++++++++++++++++++
 tests/qemu-iotests/common.filter |   5 +-
 tests/qemu-iotests/group         |   1 +
 5 files changed, 368 insertions(+), 11 deletions(-)
 create mode 100755 tests/qemu-iotests/267
 create mode 100644 tests/qemu-iotests/267.out

-- 
2.20.1

[Qemu-devel] [PATCH 1/2] block/snapshot: Restrict set of snapshot nodes

[Kevin Wolf]

Nodes involved in internal snapshots were those that were returned by
bdrv_next(), inserted and not read-only. bdrv_next() in turn returns all
nodes that are either the root node of a BlockBackend or monitor-owned
nodes.

With the typical -drive use, this worked well enough. However, in the
typical -blockdev case, the user defines one node per option, making all
nodes monitor-owned nodes. This includes protocol nodes etc. which often
are not snapshottable, so "savevm" only returns an error.

Change the conditions so that internal snapshot still include all nodes
that have a BlockBackend attached (we definitely want to snapshot
anything attached to a guest device and probably also the built-in NBD
server; snapshotting block job BlockBackends is more of an accident, but
a preexisting one), but other monitor-owned nodes are only included if
they have no parents.

This makes internal snapshots usable again with typical -blockdev
configurations.

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/snapshot.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index f2f48f926a..8081616ae9 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -31,6 +31,7 @@
 #include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qstring.h"
 #include "qemu/option.h"
+#include "sysemu/block-backend.h"
 
 QemuOptsList internal_snapshot_opts = {
     .name = "snapshot",
@@ -384,6 +385,16 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
     return ret;
 }
 
+static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
+{
+    if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
+        return false;
+    }
+
+    /* Include all nodes that are either in use by a BlockBackend, or that
+     * aren't attached to any node, but owned by the monitor. */
+    return bdrv_has_blk(bs) || QLIST_EMPTY(&bs->parents);
+}
 
 /* Group operations. All block drivers are involved.
  * These functions will properly handle dataplane (take aio_context_acquire
@@ -399,7 +410,7 @@ bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
-        if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
+        if (bdrv_all_snapshots_includes_bs(bs)) {
             ok = bdrv_can_snapshot(bs);
         }
         aio_context_release(ctx);
@@ -426,8 +437,9 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
-        if (bdrv_can_snapshot(bs) &&
-                bdrv_snapshot_find(bs, snapshot, name) >= 0) {
+        if (bdrv_all_snapshots_includes_bs(bs) &&
+            bdrv_snapshot_find(bs, snapshot, name) >= 0)
+        {
             ret = bdrv_snapshot_delete(bs, snapshot->id_str,
                                        snapshot->name, err);
         }
@@ -455,7 +467,7 @@ int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
-        if (bdrv_can_snapshot(bs)) {
+        if (bdrv_all_snapshots_includes_bs(bs)) {
             ret = bdrv_snapshot_goto(bs, name, errp);
         }
         aio_context_release(ctx);
@@ -481,7 +493,7 @@ int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
-        if (bdrv_can_snapshot(bs)) {
+        if (bdrv_all_snapshots_includes_bs(bs)) {
             err = bdrv_snapshot_find(bs, &sn, name);
         }
         aio_context_release(ctx);
@@ -512,7 +524,7 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
         if (bs == vm_state_bs) {
             sn->vm_state_size = vm_state_size;
             err = bdrv_snapshot_create(bs, sn);
-        } else if (bdrv_can_snapshot(bs)) {
+        } else if (bdrv_all_snapshots_includes_bs(bs)) {
             sn->vm_state_size = 0;
             err = bdrv_snapshot_create(bs, sn);
         }
@@ -538,7 +550,7 @@ BlockDriverState *bdrv_all_find_vmstate_bs(void)
         bool found;
 
         aio_context_acquire(ctx);
-        found = bdrv_can_snapshot(bs);
+        found = bdrv_all_snapshots_includes_bs(bs) && bdrv_can_snapshot(bs);
         aio_context_release(ctx);
 
         if (found) {
-- 
2.20.1

[Qemu-devel] [PATCH 2/2] iotests: Test internal snapshots with -blockdev

[Kevin Wolf]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/267           | 165 ++++++++++++++++++++++++++++
 tests/qemu-iotests/267.out       | 182 +++++++++++++++++++++++++++++++
 tests/qemu-iotests/common.filter |   5 +-
 tests/qemu-iotests/group         |   1 +
 4 files changed, 349 insertions(+), 4 deletions(-)
 create mode 100755 tests/qemu-iotests/267
 create mode 100644 tests/qemu-iotests/267.out

diff --git a/tests/qemu-iotests/267 b/tests/qemu-iotests/267
new file mode 100755
index 0000000000..0d085c60a7
--- /dev/null
+++ b/tests/qemu-iotests/267
@@ -0,0 +1,165 @@
+#!/usr/bin/env bash
+#
+# Test which nodes are involved in internal snapshots
+#
+# Copyright (C) 2019 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=kwolf@redhat.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm -f "$TEST_DIR/nbd"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+do_run_qemu()
+{
+    echo Testing: "$@"
+    (
+        if ! test -t 0; then
+            while read cmd; do
+                echo $cmd
+            done
+        fi
+        echo quit
+    ) | $QEMU -nographic -monitor stdio -nodefaults "$@"
+    echo
+}
+
+run_qemu()
+{
+    do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qemu | _filter_hmp |
+        _filter_generated_node_ids | _filter_imgfmt
+}
+
+size=128M
+
+run_test()
+{
+    _make_test_img $size
+    printf "savevm snap0\ninfo snapshots\nloadvm snap0\n" | run_qemu "$@" | _filter_date
+}
+
+
+echo
+echo "=== No block devices at all ==="
+echo
+
+run_test
+
+echo
+echo "=== -drive if=none ==="
+echo
+
+run_test -drive driver=file,file="$TEST_IMG",if=none
+run_test -drive driver=$IMGFMT,file="$TEST_IMG",if=none
+run_test -drive driver=$IMGFMT,file="$TEST_IMG",if=none -device virtio-blk,drive=none0
+
+echo
+echo "=== -drive if=virtio ==="
+echo
+
+run_test -drive driver=file,file="$TEST_IMG",if=virtio
+run_test -drive driver=$IMGFMT,file="$TEST_IMG",if=virtio
+
+echo
+echo "=== Simple -blockdev ==="
+echo
+
+run_test -blockdev driver=file,filename="$TEST_IMG",node-name=file
+run_test -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=$IMGFMT,file=file,node-name=fmt
+run_test -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=raw,file=file,node-name=raw \
+         -blockdev driver=$IMGFMT,file=raw,node-name=fmt
+
+echo
+echo "=== -blockdev with a filter on top ==="
+echo
+
+run_test -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=$IMGFMT,file=file,node-name=fmt \
+         -blockdev driver=copy-on-read,file=fmt,node-name=filter
+
+echo
+echo "=== -blockdev with a backing file ==="
+echo
+
+TEST_IMG="$TEST_IMG.base" _make_test_img $size
+
+IMGOPTS="backing_file=$TEST_IMG.base" \
+run_test -blockdev driver=file,filename="$TEST_IMG.base",node-name=backing-file \
+         -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=$IMGFMT,file=file,backing=backing-file,node-name=fmt
+
+IMGOPTS="backing_file=$TEST_IMG.base" \
+run_test -blockdev driver=file,filename="$TEST_IMG.base",node-name=backing-file \
+         -blockdev driver=$IMGFMT,file=backing-file,node-name=backing-fmt \
+         -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=$IMGFMT,file=file,backing=backing-fmt,node-name=fmt
+
+# A snapshot should be present on the overlay, but not the backing file
+echo Internal snapshots on overlay:
+$QEMU_IMG snapshot -l "$TEST_IMG" | _filter_date
+
+echo Internal snapshots on backing file:
+$QEMU_IMG snapshot -l "$TEST_IMG.base" | _filter_date
+
+echo
+echo "=== -blockdev with NBD server on the backing file ==="
+echo
+
+IMGOPTS="backing_file=$TEST_IMG.base" _make_test_img $size
+cat <<EOF |
+nbd_server_start unix:$TEST_DIR/nbd
+nbd_server_add -w backing-fmt
+savevm snap0
+info snapshots
+loadvm snap0
+EOF
+run_qemu -blockdev driver=file,filename="$TEST_IMG.base",node-name=backing-file \
+         -blockdev driver=$IMGFMT,file=backing-file,node-name=backing-fmt \
+         -blockdev driver=file,filename="$TEST_IMG",node-name=file \
+         -blockdev driver=$IMGFMT,file=file,backing=backing-fmt,node-name=fmt |
+         _filter_date
+
+# This time, a snapshot should be created on both files
+echo Internal snapshots on overlay:
+$QEMU_IMG snapshot -l "$TEST_IMG" | _filter_date
+
+echo Internal snapshots on backing file:
+$QEMU_IMG snapshot -l "$TEST_IMG.base" | _filter_date
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/267.out b/tests/qemu-iotests/267.out
new file mode 100644
index 0000000000..bb13f0ae3c
--- /dev/null
+++ b/tests/qemu-iotests/267.out
@@ -0,0 +1,182 @@
+QA output created by 267
+
+=== No block devices at all ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing:
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+Error: No block device can accept snapshots
+(qemu) info snapshots
+No available block device supports snapshots
+(qemu) loadvm snap0
+Error: No block device supports snapshots
+(qemu) quit
+
+
+=== -drive if=none ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -drive driver=file,file=TEST_DIR/t.IMGFMT,if=none
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+Error: Device 'none0' is writable but does not support snapshots
+(qemu) info snapshots
+No available block device supports snapshots
+(qemu) loadvm snap0
+Error: Device 'none0' is writable but does not support snapshots
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -drive driver=IMGFMT,file=TEST_DIR/t.IMGFMT,if=none
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -drive driver=IMGFMT,file=TEST_DIR/t.IMGFMT,if=none -device virtio-blk,drive=none0
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               636 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+
+=== -drive if=virtio ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -drive driver=file,file=TEST_DIR/t.IMGFMT,if=virtio
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+Error: Device 'virtio0' is writable but does not support snapshots
+(qemu) info snapshots
+No available block device supports snapshots
+(qemu) loadvm snap0
+Error: Device 'virtio0' is writable but does not support snapshots
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -drive driver=IMGFMT,file=TEST_DIR/t.IMGFMT,if=virtio
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               636 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+
+=== Simple -blockdev ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+Error: Device '' is writable but does not support snapshots
+(qemu) info snapshots
+No available block device supports snapshots
+(qemu) loadvm snap0
+Error: Device '' is writable but does not support snapshots
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=IMGFMT,file=file,node-name=fmt
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=raw,file=file,node-name=raw -blockdev driver=IMGFMT,file=raw,node-name=fmt
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+
+=== -blockdev with a filter on top ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=IMGFMT,file=file,node-name=fmt -blockdev driver=copy-on-read,file=fmt,node-name=filter
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+
+=== -blockdev with a backing file ===
+
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/t.IMGFMT.base
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT.base,node-name=backing-file -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=IMGFMT,file=file,backing=backing-file,node-name=fmt
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/t.IMGFMT.base
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT.base,node-name=backing-file -blockdev driver=IMGFMT,file=backing-file,node-name=backing-fmt -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=IMGFMT,file=file,backing=backing-fmt,node-name=fmt
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+Internal snapshots on overlay:
+Snapshot list:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+1         snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+Internal snapshots on backing file:
+
+=== -blockdev with NBD server on the backing file ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/t.IMGFMT.base
+Testing: -blockdev driver=file,filename=TEST_DIR/t.IMGFMT.base,node-name=backing-file -blockdev driver=IMGFMT,file=backing-file,node-name=backing-fmt -blockdev driver=file,filename=TEST_DIR/t.IMGFMT,node-name=file -blockdev driver=IMGFMT,file=file,backing=backing-fmt,node-name=fmt
+QEMU X.Y.Z monitor - type 'help' for more information
+(qemu) nbd_server_start unix:TEST_DIR/nbd
+(qemu) nbd_server_add -w backing-fmt
+(qemu) savevm snap0
+(qemu) info snapshots
+List of snapshots present on all disks:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+--        snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+(qemu) loadvm snap0
+(qemu) quit
+
+Internal snapshots on overlay:
+Snapshot list:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+1         snap0                   0 B yyyy-mm-dd hh:mm:ss   00:00:00.000
+Internal snapshots on backing file:
+Snapshot list:
+ID        TAG                 VM SIZE                DATE       VM CLOCK
+1         snap0               591 KiB yyyy-mm-dd hh:mm:ss   00:00:00.000
+*** done
diff --git a/tests/qemu-iotests/common.filter b/tests/qemu-iotests/common.filter
index 445a1c23e0..841f7642af 100644
--- a/tests/qemu-iotests/common.filter
+++ b/tests/qemu-iotests/common.filter
@@ -19,12 +19,9 @@
 # standard filters
 #
 
-# ctime(3) dates
-#
 _filter_date()
 {
-    $SED \
-        -e 's/[A-Z][a-z][a-z] [A-z][a-z][a-z]  *[0-9][0-9]* [0-9][0-9]:[0-9][0-9]:[0-9][0-9] [0-9][0-9][0-9][0-9]$/DATE/'
+    $SED -re 's/[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}/yyyy-mm-dd hh:mm:ss/'
 }
 
 _filter_generated_node_ids()
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 5d3da937e4..5805a79d9e 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -277,3 +277,4 @@
 263 rw quick
 265 rw auto quick
 266 rw quick
+267 rw auto quick snapshot
-- 
2.20.1

Re: [Qemu-devel] [PATCH 1/2] block/snapshot: Restrict set of snapshot nodes

[Eric Blake]

[-- Attachment #1.1: Type: text/plain, Size: 1554 bytes --]

On 9/17/19 6:04 AM, Kevin Wolf wrote:
> Nodes involved in internal snapshots were those that were returned by
> bdrv_next(), inserted and not read-only. bdrv_next() in turn returns all
> nodes that are either the root node of a BlockBackend or monitor-owned
> nodes.
> 
> With the typical -drive use, this worked well enough. However, in the
> typical -blockdev case, the user defines one node per option, making all
> nodes monitor-owned nodes. This includes protocol nodes etc. which often
> are not snapshottable, so "savevm" only returns an error.
> 
> Change the conditions so that internal snapshot still include all nodes
> that have a BlockBackend attached (we definitely want to snapshot
> anything attached to a guest device and probably also the built-in NBD
> server; snapshotting block job BlockBackends is more of an accident, but
> a preexisting one), but other monitor-owned nodes are only included if
> they have no parents.
> 
> This makes internal snapshots usable again with typical -blockdev
> configurations.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/snapshot.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)

Makes sense.  But you'll want Peter's review that it actually passes
testing with libvirt, rather than relying solely on my:

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH 0/2] block/snapshot: Restrict set of snapshot nodes

[Peter Krempa]

[-- Attachment #1: Type: text/plain, Size: 629 bytes --]

On Tue, Sep 17, 2019 at 13:04:41 +0200, Kevin Wolf wrote:
> This fixes internal snapshots with separately defined protocol nodes
> (like libvirt will do with -blockdev).

The code change is exactly what I thought would be necessary in this
case. I've tested it with my blockdev code in libvirt enabled and all
three internal snapshot commands seem to work as expected even when
fully using blockdev and also only the top layer gets the snapshot.

I'll send patches that attempt adding introspection to allow libvirt
detecting this fix.

Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>

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Re: [PATCH 2/2] iotests: Test internal snapshots with -blockdev

[Max Reitz]

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On 17.09.19 13:04, Kevin Wolf wrote:
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  tests/qemu-iotests/267           | 165 ++++++++++++++++++++++++++++
>  tests/qemu-iotests/267.out       | 182 +++++++++++++++++++++++++++++++
>  tests/qemu-iotests/common.filter |   5 +-
>  tests/qemu-iotests/group         |   1 +
>  4 files changed, 349 insertions(+), 4 deletions(-)
>  create mode 100755 tests/qemu-iotests/267
>  create mode 100644 tests/qemu-iotests/267.out
> 
> diff --git a/tests/qemu-iotests/267 b/tests/qemu-iotests/267
> new file mode 100755
> index 0000000000..0d085c60a7
> --- /dev/null
> +++ b/tests/qemu-iotests/267
> @@ -0,0 +1,165 @@
> +#!/usr/bin/env bash
> +#
> +# Test which nodes are involved in internal snapshots
> +#
> +# Copyright (C) 2019 Red Hat, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +#
> +
> +# creator
> +owner=kwolf@redhat.com
> +
> +seq=`basename $0`
> +echo "QA output created by $seq"
> +
> +status=1	# failure is the default!
> +
> +_cleanup()
> +{
> +    _cleanup_test_img
> +    rm -f "$TEST_DIR/nbd"
> +}
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +# get standard environment, filters and checks
> +. ./common.rc
> +. ./common.filter
> +
> +_supported_fmt qcow2
> +_supported_proto file
> +_supported_os Linux

This needs some restriction on what refcount_bits are supported.
(because it naturally fails with refcount_bits=1)

Max


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Re: [PATCH 1/2] block/snapshot: Restrict set of snapshot nodes

[Max Reitz]

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On 17.09.19 13:04, Kevin Wolf wrote:
> Nodes involved in internal snapshots were those that were returned by
> bdrv_next(), inserted and not read-only. bdrv_next() in turn returns all
> nodes that are either the root node of a BlockBackend or monitor-owned
> nodes.
> 
> With the typical -drive use, this worked well enough. However, in the
> typical -blockdev case, the user defines one node per option, making all
> nodes monitor-owned nodes. This includes protocol nodes etc. which often
> are not snapshottable, so "savevm" only returns an error.
> 
> Change the conditions so that internal snapshot still include all nodes
> that have a BlockBackend attached (we definitely want to snapshot
> anything attached to a guest device and probably also the built-in NBD
> server; snapshotting block job BlockBackends is more of an accident, but
> a preexisting one), but other monitor-owned nodes are only included if
> they have no parents.
> 
> This makes internal snapshots usable again with typical -blockdev
> configurations.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/snapshot.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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