Patchwork [V4] block: Add BlockDriver.bdrv_check_ext_snapshot.

login
register
mail settings
Submitter Benoît Canet
Date Oct. 2, 2013, 12:33 p.m.
Message ID <1380717228-10135-2-git-send-email-benoit@irqsave.net>
Download mbox | patch
Permalink /patch/279721/
State New
Headers show

Comments

Benoît Canet - Oct. 2, 2013, 12:33 p.m.
This field is used by blkverify to disable external snapshots creation.
I will also be used by block filters like quorum to disable external snapshots
creation.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block.c                   | 17 +++++++++++++++++
 block/blkverify.c         |  2 ++
 blockdev.c                |  5 +++++
 include/block/block.h     | 14 ++++++++++++++
 include/block/block_int.h |  6 ++++++
 5 files changed, 44 insertions(+)
Max Reitz - Oct. 2, 2013, 3:30 p.m.
On 2013-10-02 14:33, Benoît Canet wrote:
> This field is used by blkverify to disable external snapshots creation.
> I will also be used by block filters like quorum to disable external snapshots
> creation.
>
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
>   block.c                   | 17 +++++++++++++++++
>   block/blkverify.c         |  2 ++
>   blockdev.c                |  5 +++++
>   include/block/block.h     | 14 ++++++++++++++
>   include/block/block_int.h |  6 ++++++
>   5 files changed, 44 insertions(+)
>
> diff --git a/block.c b/block.c
> index 93e113a..e891522 100644
> --- a/block.c
> +++ b/block.c
> @@ -4632,3 +4632,20 @@ int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options)
>       }
>       return bs->drv->bdrv_amend_options(bs, options);
>   }
> +
> +ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
> +{
> +    /* external snashots are allowed by defaults */
I don't really know whether it should rather be "by default", but it 
certainly should be s/snashots/snapshots/. ;)
Also, I'd move this comment below the if statements and above the return 
EXT_SNAPSHOT_ALLOWED.

> +    if (bs->drv->bdrv_check_ext_snapshot) {
> +        return bs->drv->bdrv_check_ext_snapshot(bs);
> +    }
> +    if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
> +        return bs->file->drv->bdrv_check_ext_snapshot(bs);
> +    }
> +    return EXT_SNAPSHOT_ALLOWED;
> +}
> +
> +ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
> +{
> +    return EXT_SNAPSHOT_FORBIDDEN;
> +}
> diff --git a/block/blkverify.c b/block/blkverify.c
> index 2077d8a..b64c638 100644
> --- a/block/blkverify.c
> +++ b/block/blkverify.c
> @@ -313,6 +313,8 @@ static BlockDriver bdrv_blkverify = {
>       .bdrv_aio_readv         = blkverify_aio_readv,
>       .bdrv_aio_writev        = blkverify_aio_writev,
>       .bdrv_aio_flush         = blkverify_aio_flush,
> +
> +    .bdrv_check_ext_snapshot = bdrv_check_ext_snapshot_forbidden,
>   };
>   
>   static void bdrv_blkverify_init(void)
> diff --git a/blockdev.c b/blockdev.c
> index 8aa66a9..92029d8 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1131,6 +1131,11 @@ static void external_snapshot_prepare(BlkTransactionState *common,
>           }
>       }
>   
> +    if (bdrv_check_ext_snapshot(state->old_bs) != EXT_SNAPSHOT_ALLOWED) {
> +        error_set(errp, QERR_FEATURE_DISABLED, "snapshot");
> +        return;
> +    }
> +
>       flags = state->old_bs->open_flags;
>   
>       /* create new image w/backing file */
> diff --git a/include/block/block.h b/include/block/block.h
> index f808550..2bf0e12 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -244,6 +244,20 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
>   
>   int bdrv_amend_options(BlockDriverState *bs_new, QEMUOptionParameter *options);
>   
> +/* external snapshots */
> +
> +typedef enum {
> +    EXT_SNAPSHOT_ALLOWED,
> +    EXT_SNAPSHOT_FORBIDDEN,
> +} ExtSnapshotPerm;
> +
> +/* return EXT_SNAPSHOT_ALLOWED if external snapshot is allowed
> + * return EXT_SNAPSHOT_FORBIDEN if external snapshot is forbiden
s/FORBIDEN/FORBIDDEN/, s/forbiden/forbidden/

> + */
> +ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs);
> +/* helper used to forbid external snapshots like in blkverify */
> +ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs);
> +
>   /* async block I/O */
>   typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
>                                        int sector_num);
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 211087a..e6a14ae 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -67,6 +67,12 @@ typedef struct BdrvTrackedRequest {
>   struct BlockDriver {
>       const char *format_name;
>       int instance_size;
> +
> +    /* if not defined external snapshots are allowed
> +     * future block filters will query their children to build the response
> +     */
> +    ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs);
> +
>       int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
>       int (*bdrv_probe_device)(const char *filename);
>   

Aside from the misspellings (and regardless of whether you decide to 
move the comment or not):

Reviewed-by: Max Reitz <mreitz@redhat.com>
Max Reitz - Oct. 2, 2013, 3:33 p.m.
On 2013-10-02 14:33, Benoît Canet wrote:
> This field is used by blkverify to disable external snapshots creation.
> I will also be used by block filters like quorum to disable external snapshots
> creation.
Oh, I nearly missed it: s/I will also be/It will also be/ and probably 
s/external snapshots creation/external snapshot creation/, but I'm not 
too sure about the last one.
Eric Blake - Oct. 2, 2013, 3:42 p.m.
On 10/02/2013 09:33 AM, Max Reitz wrote:
> On 2013-10-02 14:33, Benoît Canet wrote:
>> This field is used by blkverify to disable external snapshots creation.
>> I will also be used by block filters like quorum to disable external
>> snapshots
>> creation.
> Oh, I nearly missed it: s/I will also be/It will also be/ and probably
> s/external snapshots creation/external snapshot creation/, but I'm not
> too sure about the last one.

As a native speaker, yes, that last change sounds better ("to disable
external snapshot creation").
Kevin Wolf - Oct. 9, 2013, 10:22 a.m.
Am 02.10.2013 um 17:30 hat Max Reitz geschrieben:
> On 2013-10-02 14:33, Benoît Canet wrote:
> >This field is used by blkverify to disable external snapshots creation.
> >I will also be used by block filters like quorum to disable external snapshots
> >creation.
> >
> >Signed-off-by: Benoit Canet <benoit@irqsave.net>

> Aside from the misspellings (and regardless of whether you decide to
> move the comment or not):
> 
> Reviewed-by: Max Reitz <mreitz@redhat.com>

Thanks, fixed up spelling and formatting and applied to the block
branch.

Kevin

Patch

diff --git a/block.c b/block.c
index 93e113a..e891522 100644
--- a/block.c
+++ b/block.c
@@ -4632,3 +4632,20 @@  int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options)
     }
     return bs->drv->bdrv_amend_options(bs, options);
 }
+
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+{
+    /* external snashots are allowed by defaults */
+    if (bs->drv->bdrv_check_ext_snapshot) {
+        return bs->drv->bdrv_check_ext_snapshot(bs);
+    }
+    if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
+        return bs->file->drv->bdrv_check_ext_snapshot(bs);
+    }
+    return EXT_SNAPSHOT_ALLOWED;
+}
+
+ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+{
+    return EXT_SNAPSHOT_FORBIDDEN;
+}
diff --git a/block/blkverify.c b/block/blkverify.c
index 2077d8a..b64c638 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -313,6 +313,8 @@  static BlockDriver bdrv_blkverify = {
     .bdrv_aio_readv         = blkverify_aio_readv,
     .bdrv_aio_writev        = blkverify_aio_writev,
     .bdrv_aio_flush         = blkverify_aio_flush,
+
+    .bdrv_check_ext_snapshot = bdrv_check_ext_snapshot_forbidden,
 };
 
 static void bdrv_blkverify_init(void)
diff --git a/blockdev.c b/blockdev.c
index 8aa66a9..92029d8 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1131,6 +1131,11 @@  static void external_snapshot_prepare(BlkTransactionState *common,
         }
     }
 
+    if (bdrv_check_ext_snapshot(state->old_bs) != EXT_SNAPSHOT_ALLOWED) {
+        error_set(errp, QERR_FEATURE_DISABLED, "snapshot");
+        return;
+    }
+
     flags = state->old_bs->open_flags;
 
     /* create new image w/backing file */
diff --git a/include/block/block.h b/include/block/block.h
index f808550..2bf0e12 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -244,6 +244,20 @@  int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
 
 int bdrv_amend_options(BlockDriverState *bs_new, QEMUOptionParameter *options);
 
+/* external snapshots */
+
+typedef enum {
+    EXT_SNAPSHOT_ALLOWED,
+    EXT_SNAPSHOT_FORBIDDEN,
+} ExtSnapshotPerm;
+
+/* return EXT_SNAPSHOT_ALLOWED if external snapshot is allowed
+ * return EXT_SNAPSHOT_FORBIDEN if external snapshot is forbiden
+ */
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs);
+/* helper used to forbid external snapshots like in blkverify */
+ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs);
+
 /* async block I/O */
 typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
                                      int sector_num);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 211087a..e6a14ae 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -67,6 +67,12 @@  typedef struct BdrvTrackedRequest {
 struct BlockDriver {
     const char *format_name;
     int instance_size;
+
+    /* if not defined external snapshots are allowed
+     * future block filters will query their children to build the response
+     */
+    ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs);
+
     int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
     int (*bdrv_probe_device)(const char *filename);