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backup: add minimum cluster size to performance options

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In the context of backup fleecing, discarding the source will not work
when the fleecing image has a larger granularity than the one used for
block-copy operations (can happen if the backup target has smaller
cluster size), because cbw_co_pdiscard_snapshot() will align down the
discard requests and thus effectively ignore then.

To make @discard-source work in such a scenario, allow specifying the
minimum cluster size used for block-copy operations and thus in
particular also the granularity for discard requests to the source.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Acked-by: Markus Armbruster <armbru@redhat.com> (QAPI schema)
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-Id: <20240711120915.310243-3-f.ebner@proxmox.com>
[vsementsov: switch version to 9.2 in QAPI doc]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
This commit is contained in:
Fiona Ebner 2024-07-11 14:09:15 +02:00 committed by Vladimir Sementsov-Ogievskiy
parent 9484ad6c17
commit 6252deb244
5 changed files with 21 additions and 3 deletions
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2
block/backup.c
View File

@ -458,7 +458,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
}
cbw = bdrv_cbw_append(bs, target, filter_node_name, discard_source,
&bcs, errp);
perf->min_cluster_size, &bcs, errp);
if (!cbw) {
goto error;
}

9
block/copy-before-write.c
View File

@ -548,6 +548,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
BlockDriverState *target,
const char *filter_node_name,
bool discard_source,
uint64_t min_cluster_size,
BlockCopyState **bcs,
Error **errp)
{
@ -567,6 +568,14 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
qdict_put_str(opts, "file", bdrv_get_node_name(source));
qdict_put_str(opts, "target", bdrv_get_node_name(target));
if (min_cluster_size > INT64_MAX) {
error_setg(errp, "min-cluster-size too large: %" PRIu64 " > %" PRIi64,
min_cluster_size, INT64_MAX);
qobject_unref(opts);
return NULL;
}
qdict_put_int(opts, "min-cluster-size", (int64_t)min_cluster_size);
top = bdrv_insert_node(source, opts, flags, errp);
if (!top) {
return NULL;

1
block/copy-before-write.h
View File

@ -40,6 +40,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
BlockDriverState *target,
const char *filter_node_name,
bool discard_source,
uint64_t min_cluster_size,
BlockCopyState **bcs,
Error **errp);
void bdrv_cbw_drop(BlockDriverState *bs);

3
blockdev.c
View File

@ -2655,6 +2655,9 @@ static BlockJob *do_backup_common(BackupCommon *backup,
if (backup->x_perf->has_max_chunk) {
perf.max_chunk = backup->x_perf->max_chunk;
}
if (backup->x_perf->has_min_cluster_size) {
perf.min_cluster_size = backup->x_perf->min_cluster_size;
}
}
if ((backup->sync == MIRROR_SYNC_MODE_BITMAP) ||

9
qapi/block-core.json
View File

@ -1551,11 +1551,16 @@
# it should not be less than job cluster size which is calculated
# as maximum of target image cluster size and 64k. Default 0.
#
# @min-cluster-size: Minimum size of blocks used by copy-before-write
# and background copy operations. Has to be a power of 2. No
# effect if smaller than the maximum of the target's cluster size
# and 64 KiB. Default 0. (Since 9.2)
#
# Since: 6.0
##
{ 'struct': 'BackupPerf',
'data': { '*use-copy-range': 'bool',
'*max-workers': 'int', '*max-chunk': 'int64' } }
'data': { '*use-copy-range': 'bool', '*max-workers': 'int',
'*max-chunk': 'int64', '*min-cluster-size': 'size' } }
##
# @BackupCommon: