[Qemu-devel] [PATCH 0/3] Show files ancestors count in HMP

[Qemu-devel] [PATCH 0/3] Show files ancestors count in HMP

[benoit.canet]

From: Benoît Canet <benoit@irqsave.net>

In some setups many backing files and snapshot are chained.
This lead to the formation of huge trees of snapshots all depending
on a common ancestor.

Hence if something bad happen to this common ancestor all the snapshot
of the tree will be broken.

This patch add an easy way for the user to monitor backing file ancestors
count and take the good decision (streaming).

Benoît Canet (3):
  block: Add bdrv_are_busy()
  qerror: Add error telling that block dev usage prevents migration
  migration: block migration when any of the block device is busy

 block.c     |   13 +++++++++++++
 block.h     |    2 ++
 migration.c |    5 +++++
 qerror.c    |    4 ++++
 qerror.h    |    3 +++
 5 files changed, 27 insertions(+)

-- 
1.7.9.5

[Qemu-devel] [PATCH 1/3] block: create bdrv_get_file_ancestors_count()

[benoit.canet]

From: Benoît Canet <benoit@irqsave.net>

Create bdrv_get_file_ancestors_count() in order to be
able to show in QMP and HMP how many ancestors backing an image a
block device have.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block.c |   13 +++++++++++++
 block.h |    1 +
 2 files changed, 14 insertions(+)

diff --git a/block.c b/block.c
index ce7eb8f..1128356 100644
--- a/block.c
+++ b/block.c
@@ -2754,6 +2754,19 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     return NULL;
 }
 
+int bdrv_get_file_ancestors_count(BlockDriverState *bs)
+{
+    if (!bs->drv) {
+        return 0;
+    }
+
+    if (!bs->backing_hd) {
+        return 0;
+    }
+
+    return 1 + bdrv_get_file_ancestors_count(bs->backing_hd);
+}
+
 #define NB_SUFFIXES 4
 
 char *get_human_readable_size(char *buf, int buf_size, int64_t size)
diff --git a/block.h b/block.h
index c89590d..8114ed0 100644
--- a/block.h
+++ b/block.h
@@ -174,6 +174,7 @@ int coroutine_fn bdrv_co_is_allocated_above(BlockDriverState *top,
                                             int nb_sectors, int *pnum);
 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     const char *backing_file);
+int bdrv_get_file_ancestors_count(BlockDriverState *bs);
 int bdrv_truncate(BlockDriverState *bs, int64_t offset);
 int64_t bdrv_getlength(BlockDriverState *bs);
 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
-- 
1.7.9.5

[Qemu-devel] [PATCH 2/3] block: Use file_ancestors_count() in qmp_query_block

[benoit.canet]

From: Benoît Canet <benoit@irqsave.net>

Use the dedicated counting function in qmp_query_block in order to
propagate the backing file count to HMP.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block.c          |    2 ++
 qapi-schema.json |    9 ++++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/block.c b/block.c
index 1128356..23b4aab 100644
--- a/block.c
+++ b/block.c
@@ -2448,6 +2448,8 @@ BlockInfoList *qmp_query_block(Error **errp)
             if (bs->backing_file[0]) {
                 info->value->inserted->has_backing_file = true;
                 info->value->inserted->backing_file = g_strdup(bs->backing_file);
+                info->value->inserted->file_ancestors_count =
+                    bdrv_get_file_ancestors_count(bs);
             }
 
             if (bs->io_limits_enabled) {
diff --git a/qapi-schema.json b/qapi-schema.json
index a92adb1..1ae0fc7 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -398,6 +398,8 @@
 #
 # @backing_file: #optional the name of the backing file (for copy-on-write)
 #
+# @file_ancestors_count: #optional the count of ancestors backing files (for copy-on-write)
+#
 # @encrypted: true if the backing device is encrypted
 #
 # @bps: total throughput limit in bytes per second is specified
@@ -418,9 +420,10 @@
 ##
 { 'type': 'BlockDeviceInfo',
   'data': { 'file': 'str', 'ro': 'bool', 'drv': 'str',
-            '*backing_file': 'str', 'encrypted': 'bool',
-            'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
-            'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int'} }
+            '*backing_file': 'str', 'file_ancestors_count', 'int',
+            'encrypted': 'bool', 'bps': 'int', 'bps_rd': 'int',
+            'bps_wr': 'int', 'iops': 'int', 'iops_rd': 'int',
+            'iops_wr': 'int'} }
 
 ##
 # @BlockDeviceIoStatus:
-- 
1.7.9.5

[Qemu-devel] [PATCH 3/3] hmp: show the files ancestors count

[benoit.canet]

From: Benoît Canet <benoit@irqsave.net>

Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 hmp.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/hmp.c b/hmp.c
index 6b72a64..025c59f 100644
--- a/hmp.c
+++ b/hmp.c
@@ -227,6 +227,8 @@ void hmp_info_block(Monitor *mon)
             if (info->value->inserted->has_backing_file) {
                 monitor_printf(mon, " backing_file=");
                 monitor_print_filename(mon, info->value->inserted->backing_file);
+                monitor_printf(mon, " file_ancestors_count=%" PRId64,
+                    info->value->inserted->file_ancestors_count);
             }
             monitor_printf(mon, " ro=%d drv=%s encrypted=%d",
                            info->value->inserted->ro,
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 2/3] block: Use file_ancestors_count() in qmp_query_block

[Luiz Capitulino]

On Mon, 23 Jul 2012 16:56:54 +0200
benoit.canet@gmail.com wrote:

> From: Benoît Canet <benoit@irqsave.net>
> 
> Use the dedicated counting function in qmp_query_block in order to
> propagate the backing file count to HMP.
> 
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>  block.c          |    2 ++
>  qapi-schema.json |    9 ++++++---
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 1128356..23b4aab 100644
> --- a/block.c
> +++ b/block.c
> @@ -2448,6 +2448,8 @@ BlockInfoList *qmp_query_block(Error **errp)
>              if (bs->backing_file[0]) {
>                  info->value->inserted->has_backing_file = true;
>                  info->value->inserted->backing_file = g_strdup(bs->backing_file);
> +                info->value->inserted->file_ancestors_count =
> +                    bdrv_get_file_ancestors_count(bs);
>              }
>  
>              if (bs->io_limits_enabled) {
> diff --git a/qapi-schema.json b/qapi-schema.json
> index a92adb1..1ae0fc7 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -398,6 +398,8 @@
>  #
>  # @backing_file: #optional the name of the backing file (for copy-on-write)
>  #
> +# @file_ancestors_count: #optional the count of ancestors backing files (for copy-on-write)
> +#
>  # @encrypted: true if the backing device is encrypted
>  #
>  # @bps: total throughput limit in bytes per second is specified
> @@ -418,9 +420,10 @@
>  ##
>  { 'type': 'BlockDeviceInfo',
>    'data': { 'file': 'str', 'ro': 'bool', 'drv': 'str',
> -            '*backing_file': 'str', 'encrypted': 'bool',
> -            'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
> -            'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int'} }
> +            '*backing_file': 'str', 'file_ancestors_count', 'int',

Syntax error, it should be 'file_ancestors_count: int'. And, wouldn't
be better to call it backing_file_ancestors_count?

Otherwise the qmp part looks good to me.

> +            'encrypted': 'bool', 'bps': 'int', 'bps_rd': 'int',
> +            'bps_wr': 'int', 'iops': 'int', 'iops_rd': 'int',
> +            'iops_wr': 'int'} }
>  
>  ##
>  # @BlockDeviceIoStatus: