Re: [Qemu-devel] [PATCH 12/14] backup: Use BlockBackend for I/O

[Max Reitz]

On 04.05.2016 11:39, Kevin Wolf wrote:
> This changes the backup block job to use the job's BlockBackend for
> performing its I/O. job->bs isn't used by the backup code any more
> afterwards.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block/backup.c                 | 42 
> ++++++++++++++++++++++--------------------
>  block/block-backend.c          | 14 ++++++++++++++
>  block/io.c                     |  9 ---------
>  blockdev.c                     |  4 +---
>  include/block/block.h          |  2 --
>  include/sysemu/block-backend.h |  2 ++
>  trace-events                   |  2 +-
>  7 files changed, 40 insertions(+), 35 deletions(-)
> 
> diff --git a/block/backup.c b/block/backup.c
> index 670ba50..ba9eb42 100644
> --- a/block/backup.c
> +++ b/block/backup.c

[...]

> @@ -548,9 +547,11 @@ void backup_start(BlockDriverState *bs, BlockDriverState 
> *target,
>          goto error;
>      }
>  
> +    job->target = blk_new(&error_abort);

*cough*

> +    blk_insert_bs(job->target, target);
> +
>      job->on_source_error = on_source_error;
>      job->on_target_error = on_target_error;
> -    job->target = target;
>      job->sync_mode = sync_mode;
>      job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
>                         sync_bitmap : NULL;

[...]

> diff --git a/block/block-backend.c b/block/block-backend.c
> index 8dc3aa5..2b3c55f 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -807,6 +807,20 @@ int coroutine_fn blk_co_readv(BlockBackend *blk, int64_t 
> sector_num,
>                           nb_sectors << BDRV_SECTOR_BITS, qiov, 0);
>  }
>  
> +int coroutine_fn blk_co_readv_no_serialising(BlockBackend *blk,
> +    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
> +{
> +    trace_blk_co_readv_no_serialising(blk, blk_bs(blk), sector_num, 
> nb_sectors);
> +
> +    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
> +        return -EINVAL;
> +    }
> +
> +    return blk_co_preadv(blk, sector_num << BDRV_SECTOR_BITS,
> +                         nb_sectors << BDRV_SECTOR_BITS, qiov,
> +                         BDRV_REQ_NO_SERIALISING);
> +}
> +

Same concern as in the other places whether we really want this to have
a sector-based interface...

>  int coroutine_fn blk_co_copy_on_readv(BlockBackend *blk,
>      int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
>  {

[...]

> diff --git a/blockdev.c b/blockdev.c
> index 7a0196f..fa381ce 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3268,8 +3268,8 @@ static void do_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, txn, &local_err);
> +    bdrv_unref(target_bs);

Alternatively you could pull it down under the "out" label and then
remove another bdrv_unref(target_bs) instance in this function.

Max

>      if (local_err != NULL) {
> -        bdrv_unref(target_bs);
>          error_propagate(errp, local_err);
>          goto out;
>      }

signature.asc
Description: OpenPGP digital signature