Re: [Qemu-block] [PATCH v5 07/12] block: Add "drained begin/end" for transactional backup

[Jeff Cody]

On Wed, Oct 21, 2015 at 10:06:44AM +0800, Fam Zheng wrote:
> This ensures the atomicity of the transaction by avoiding processing of
> external requests such as those from ioeventfd.
> 
> Move the assignment to state->bs up right after bdrv_drained_begin, so
> that we can use it in the clean callback. The abort callback will still
> check bs->job and state->job, so it's OK.
> 
> Signed-off-by: Fam Zheng 
> ---
>  blockdev.c | 9 -
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index e4a5eb4..0a7848b 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1684,9 +1684,16 @@ static void drive_backup_prepare(BlkTransactionState 
> *common, Error **errp)
>  return;
>  }
>  
> +if (!blk_is_available(blk)) {
> +error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, backup->device);
> +return;
> +}
> +
>  /* AioContext is released in .clean() */
>  state->aio_context = blk_get_aio_context(blk);
>  aio_context_acquire(state->aio_context);
> +bdrv_drained_begin(blk_bs(blk));
> +state->bs = blk_bs(blk);
>  
>  qmp_drive_backup(backup->device, backup->target,
>   backup->has_format, backup->format,
> @@ -1702,7 +1709,6 @@ static void drive_backup_prepare(BlkTransactionState 
> *common, Error **errp)
>  return;
>  }
>  
> -state->bs = blk_bs(blk);
>  state->job = state->bs->job;
>  }
>  
> @@ -1722,6 +1728,7 @@ static void drive_backup_clean(BlkTransactionState 
> *common)
>  DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
>  
>  if (state->aio_context) {
> +bdrv_drained_end(state->bs);
>  aio_context_release(state->aio_context);
>  }
>  }
> -- 
> 2.4.3
> 
> 

Reviewed-by: Jeff Cody 

[Qemu-block] [PATCH v5 07/12] block: Add "drained begin/end" for transactional backup

[Fam Zheng]

This ensures the atomicity of the transaction by avoiding processing of
external requests such as those from ioeventfd.

Move the assignment to state->bs up right after bdrv_drained_begin, so
that we can use it in the clean callback. The abort callback will still
check bs->job and state->job, so it's OK.

Signed-off-by: Fam Zheng 
---
 blockdev.c | 9 -
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/blockdev.c b/blockdev.c
index e4a5eb4..0a7848b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1684,9 +1684,16 @@ static void drive_backup_prepare(BlkTransactionState 
*common, Error **errp)
 return;
 }
 
+if (!blk_is_available(blk)) {
+error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, backup->device);
+return;
+}
+
 /* AioContext is released in .clean() */
 state->aio_context = blk_get_aio_context(blk);
 aio_context_acquire(state->aio_context);
+bdrv_drained_begin(blk_bs(blk));
+state->bs = blk_bs(blk);
 
 qmp_drive_backup(backup->device, backup->target,
  backup->has_format, backup->format,
@@ -1702,7 +1709,6 @@ static void drive_backup_prepare(BlkTransactionState 
*common, Error **errp)
 return;
 }
 
-state->bs = blk_bs(blk);
 state->job = state->bs->job;
 }
 
@@ -1722,6 +1728,7 @@ static void drive_backup_clean(BlkTransactionState 
*common)
 DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
 
 if (state->aio_context) {
+bdrv_drained_end(state->bs);
 aio_context_release(state->aio_context);
 }
 }
-- 
2.4.3