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block: Add BDS.never_freeze

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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 <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190703172813.6868-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2019-07-03 19:28:02 +02:00
parent 95667c3be0
commit e5182c1c57
4 changed files with 19 additions and 0 deletions
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8
block.c
View File

@ -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;

4
block/commit.c
View File

@ -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);

4
block/mirror.c
View File

@ -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 |

3
include/block/block_int.h
View File

@ -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 {