On 28/06/2019 01:32, Max Reitz wrote:
> The commit and the mirror block job must be able to drop their filter
> node at any point. However, this will not be possible if any of the
> BdrvChild links to them is frozen. Therefore, we need to prevent them
> from ever becoming frozen.
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> ---
> include/block/block_int.h | 3 +++
> block.c | 8 ++++++++
> block/commit.c | 4 ++++
> block/mirror.c | 4 ++++
> 4 files changed, 19 insertions(+)
>
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index d6415b53c1..50902531b7 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -885,6 +885,9 @@ struct BlockDriverState {
>
> /* Only read/written by whoever has set active_flush_req to true. */
> unsigned int flushed_gen; /* Flushed write generation */
> +
> + /* BdrvChild links to this node may never be frozen */
> + bool never_freeze;
> };
>
> struct BlockBackendRootState {
> diff --git a/block.c b/block.c
> index c139540f2b..6565192b91 100644
> --- a/block.c
> +++ b/block.c
> @@ -4416,6 +4416,14 @@ int bdrv_freeze_backing_chain(BlockDriverState *bs,
> BlockDriverState *base,
> return -EPERM;
> }
>
> + for (i = bs; i != base; i = backing_bs(i)) {
> + if (i->backing && backing_bs(i)->never_freeze) {
> + error_setg(errp, "Cannot freeze '%s' link to '%s'",
> + i->backing->name, backing_bs(i)->node_name);
> + return -EPERM;
> + }
> + }
> +
> for (i = bs; i != base; i = backing_bs(i)) {
> if (i->backing) {
> i->backing->frozen = true;
> diff --git a/block/commit.c b/block/commit.c
> index ca7e408b26..2c5a6d4ebc 100644
> --- a/block/commit.c
> +++ b/block/commit.c
> @@ -298,6 +298,10 @@ void commit_start(const char *job_id, BlockDriverState
> *bs,
> if (!filter_node_name) {
> commit_top_bs->implicit = true;
> }
> +
> + /* So that we can always drop this node */
> + commit_top_bs->never_freeze = true;
> +
> commit_top_bs->total_sectors = top->total_sectors;
>
> bdrv_append(commit_top_bs, top, &local_err);
> diff --git a/block/mirror.c b/block/mirror.c
> index 2fcec70e35..8cb75fb409 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -1551,6 +1551,10 @@ static BlockJob *mirror_start_job(
> if (!filter_node_name) {
> mirror_top_bs->implicit = true;
> }
> +
> + /* So that we can always drop this node */
> + mirror_top_bs->never_freeze = true;
> +
> mirror_top_bs->total_sectors = bs->total_sectors;
> mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
> mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
>
Reviewed-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com>
--
With the best regards,
Andrey Shinkevich
