Re: [Qemu-devel] [PATCH 07/10] block/backup: support block job transactions

[Fam Zheng <famz@redhat.com>]

On Thu, 06/25 13:12, Stefan Hajnoczi wrote:
> Join the transaction when the backup block job is in incremental backup
> mode.
> 
> This ensures that the sync bitmap is not thrown away if another block
> job in the transaction is cancelled or fails.  This is critical so
> incremental backup with multiple disks can be retried in case of
> cancellation/failure.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Fam Zheng <famz@redhat.com>

> ---
>  block/backup.c |  7 +++++-
>  blockdev.c     | 73 ++++++++++++++++++++++++++++++++++++++++++----------------
>  2 files changed, 59 insertions(+), 21 deletions(-)
> 
> diff --git a/block/backup.c b/block/backup.c
> index ddf8424..fa86b0e 100644
> --- a/block/backup.c
> +++ b/block/backup.c
> @@ -429,6 +429,8 @@ static void coroutine_fn backup_run(void *opaque)
>      qemu_co_rwlock_wrlock(&job->flush_rwlock);
>      qemu_co_rwlock_unlock(&job->flush_rwlock);
>  
> +    block_job_txn_prepare_to_complete(job->common.txn, &job->common, ret);
> +
>      if (job->sync_bitmap) {
>          BdrvDirtyBitmap *bm;
>          if (ret < 0 || block_job_is_cancelled(&job->common)) {
> @@ -457,7 +459,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
>                    BlockdevOnError on_source_error,
>                    BlockdevOnError on_target_error,
>                    BlockCompletionFunc *cb, void *opaque,
> -                  Error **errp)
> +                  BlockJobTxn *txn, Error **errp)
>  {
>      int64_t len;
>  
> @@ -537,6 +539,9 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
>      job->sync_mode = sync_mode;
>      job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_DIRTY_BITMAP ?
>                         sync_bitmap : NULL;
> +    if (job->sync_bitmap) {
> +        block_job_txn_add_job(txn, &job->common);
> +    }
>      job->common.len = len;
>      job->common.co = qemu_coroutine_create(backup_run);
>      qemu_coroutine_enter(job->common.co, job);
> diff --git a/blockdev.c b/blockdev.c
> index 453f3ec..4f27c35 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1586,6 +1586,18 @@ typedef struct DriveBackupState {
>      BlockJob *job;
>  } DriveBackupState;
>  
> +static void do_drive_backup(const char *device, const char *target,
> +                            bool has_format, const char *format,
> +                            enum MirrorSyncMode sync,
> +                            bool has_mode, enum NewImageMode mode,
> +                            bool has_speed, int64_t speed,
> +                            bool has_bitmap, const char *bitmap,
> +                            bool has_on_source_error,
> +                            BlockdevOnError on_source_error,
> +                            bool has_on_target_error,
> +                            BlockdevOnError on_target_error,
> +                            BlockJobTxn *txn, Error **errp);
> +
>  static void drive_backup_prepare(BlkActionState *common, Error **errp)
>  {
>      DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
> @@ -1609,15 +1621,16 @@ static void drive_backup_prepare(BlkActionState *common, Error **errp)
>      state->aio_context = bdrv_get_aio_context(bs);
>      aio_context_acquire(state->aio_context);
>  
> -    qmp_drive_backup(backup->device, backup->target,
> -                     backup->has_format, backup->format,
> -                     backup->sync,
> -                     backup->has_mode, backup->mode,
> -                     backup->has_speed, backup->speed,
> -                     backup->has_bitmap, backup->bitmap,
> -                     backup->has_on_source_error, backup->on_source_error,
> -                     backup->has_on_target_error, backup->on_target_error,
> -                     &local_err);
> +    do_drive_backup(backup->device, backup->target,
> +                    backup->has_format, backup->format,
> +                    backup->sync,
> +                    backup->has_mode, backup->mode,
> +                    backup->has_speed, backup->speed,
> +                    backup->has_bitmap, backup->bitmap,
> +                    backup->has_on_source_error, backup->on_source_error,
> +                    backup->has_on_target_error, backup->on_target_error,
> +                    common->block_job_txn,
> +                    &local_err);
>      if (local_err) {
>          error_propagate(errp, local_err);
>          return;
> @@ -2585,15 +2598,17 @@ out:
>      aio_context_release(aio_context);
>  }
>  
> -void qmp_drive_backup(const char *device, const char *target,
> -                      bool has_format, const char *format,
> -                      enum MirrorSyncMode sync,
> -                      bool has_mode, enum NewImageMode mode,
> -                      bool has_speed, int64_t speed,
> -                      bool has_bitmap, const char *bitmap,
> -                      bool has_on_source_error, BlockdevOnError on_source_error,
> -                      bool has_on_target_error, BlockdevOnError on_target_error,
> -                      Error **errp)
> +static void do_drive_backup(const char *device, const char *target,
> +                            bool has_format, const char *format,
> +                            enum MirrorSyncMode sync,
> +                            bool has_mode, enum NewImageMode mode,
> +                            bool has_speed, int64_t speed,
> +                            bool has_bitmap, const char *bitmap,
> +                            bool has_on_source_error,
> +                            BlockdevOnError on_source_error,
> +                            bool has_on_target_error,
> +                            BlockdevOnError on_target_error,
> +                            BlockJobTxn *txn, Error **errp)
>  {
>      BlockBackend *blk;
>      BlockDriverState *bs;
> @@ -2710,7 +2725,7 @@ void qmp_drive_backup(const char *device, const char *target,
>  
>      backup_start(bs, target_bs, speed, sync, bmap,
>                   on_source_error, on_target_error,
> -                 block_job_cb, bs, &local_err);
> +                 block_job_cb, bs, txn, &local_err);
>      if (local_err != NULL) {
>          bdrv_unref(target_bs);
>          error_propagate(errp, local_err);
> @@ -2721,6 +2736,24 @@ out:
>      aio_context_release(aio_context);
>  }
>  
> +void qmp_drive_backup(const char *device, const char *target,
> +                      bool has_format, const char *format,
> +                      enum MirrorSyncMode sync,
> +                      bool has_mode, enum NewImageMode mode,
> +                      bool has_speed, int64_t speed,
> +                      bool has_bitmap, const char *bitmap,
> +                      bool has_on_source_error, BlockdevOnError on_source_error,
> +                      bool has_on_target_error, BlockdevOnError on_target_error,
> +                      Error **errp)
> +{
> +    return do_drive_backup(device, target, has_format, format, sync,
> +                           has_mode, mode, has_speed, speed,
> +                           has_bitmap, bitmap,
> +                           has_on_source_error, on_source_error,
> +                           has_on_target_error, on_target_error,
> +                           NULL, errp);
> +}
> +
>  BlockDeviceInfoList *qmp_query_named_block_nodes(Error **errp)
>  {
>      return bdrv_named_nodes_list(errp);
> @@ -2771,7 +2804,7 @@ void qmp_blockdev_backup(const char *device, const char *target,
>      bdrv_ref(target_bs);
>      bdrv_set_aio_context(target_bs, aio_context);
>      backup_start(bs, target_bs, speed, sync, NULL, on_source_error,
> -                 on_target_error, block_job_cb, bs, &local_err);
> +                 on_target_error, block_job_cb, bs, NULL, &local_err);
>      if (local_err != NULL) {
>          bdrv_unref(target_bs);
>          error_propagate(errp, local_err);
> -- 
> 2.4.3
> 
>