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block/backup: refactor: split out backup_calculate_cluster_size 

Split out cluster_size calculation. Move copy-bitmap creation above
block-job creation, as we are going to share it with upcoming
backup-top filter, which also should be created before actual block job
creation.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190429090842.57910-6-vsementsov@virtuozzo.com
[mreitz: Dropped a paragraph from the commit message that was left over
         from a previous version]
Signed-off-by: Max Reitz <mreitz@redhat.com>
stable-4.1
Vladimir Sementsov-Ogievskiy 2019-04-29 12:08:42 +03:00 committed by Max Reitz
parent c334e897d0
commit ae6b12fa4c
1 changed files with 52 additions and 30 deletions
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82
block/backup.c
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@ -497,6 +497,42 @@ static const BlockJobDriver backup_job_driver = {
.drain = backup_drain,
};
static int64_t backup_calculate_cluster_size(BlockDriverState *target,
Error **errp)
{
int ret;
BlockDriverInfo bdi;
/*
* If there is no backing file on the target, we cannot rely on COW if our
* backup cluster size is smaller than the target cluster size. Even for
* targets with a backing file, try to avoid COW if possible.
*/
ret = bdrv_get_info(target, &bdi);
if (ret == -ENOTSUP && !target->backing) {
/* Cluster size is not defined */
warn_report("The target block device doesn't provide "
"information about the block size and it doesn't have a "
"backing file. The default block size of %u bytes is "
"used. If the actual block size of the target exceeds "
"this default, the backup may be unusable",
BACKUP_CLUSTER_SIZE_DEFAULT);
return BACKUP_CLUSTER_SIZE_DEFAULT;
} else if (ret < 0 && !target->backing) {
error_setg_errno(errp, -ret,
"Couldn't determine the cluster size of the target image, "
"which has no backing file");
error_append_hint(errp,
"Aborting, since this may create an unusable destination image\n");
return ret;
} else if (ret < 0 && target->backing) {
/* Not fatal; just trudge on ahead. */
return BACKUP_CLUSTER_SIZE_DEFAULT;
}
return MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
}
BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
BlockDriverState *target, int64_t speed,
MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
@ -508,9 +544,10 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
JobTxn *txn, Error **errp)
{
int64_t len;
BlockDriverInfo bdi;
BackupBlockJob *job = NULL;
int ret;
int64_t cluster_size;
HBitmap *copy_bitmap = NULL;
assert(bs);
assert(target);
@ -572,6 +609,13 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
goto error;
}
cluster_size = backup_calculate_cluster_size(target, errp);
if (cluster_size < 0) {
goto error;
}
copy_bitmap = hbitmap_alloc(len, ctz32(cluster_size));
/* job->len is fixed, so we can't allow resize */
job = block_job_create(job_id, &backup_job_driver, txn, bs,
BLK_PERM_CONSISTENT_READ,
@ -600,35 +644,9 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
/* Detect image-fleecing (and similar) schemes */
job->serialize_target_writes = bdrv_chain_contains(target, bs);
/* If there is no backing file on the target, we cannot rely on COW if our
* backup cluster size is smaller than the target cluster size. Even for
* targets with a backing file, try to avoid COW if possible. */
ret = bdrv_get_info(target, &bdi);
if (ret == -ENOTSUP && !target->backing) {
/* Cluster size is not defined */
warn_report("The target block device doesn't provide "
"information about the block size and it doesn't have a "
"backing file. The default block size of %u bytes is "
"used. If the actual block size of the target exceeds "
"this default, the backup may be unusable",
BACKUP_CLUSTER_SIZE_DEFAULT);
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
} else if (ret < 0 && !target->backing) {
error_setg_errno(errp, -ret,
"Couldn't determine the cluster size of the target image, "
"which has no backing file");
error_append_hint(errp,
"Aborting, since this may create an unusable destination image\n");
goto error;
} else if (ret < 0 && target->backing) {
/* Not fatal; just trudge on ahead. */
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
} else {
job->cluster_size = MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
}
job->copy_bitmap = hbitmap_alloc(len, ctz32(job->cluster_size));
job->cluster_size = cluster_size;
job->copy_bitmap = copy_bitmap;
copy_bitmap = NULL;
job->use_copy_range = true;
job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk),
blk_get_max_transfer(job->target));
@ -644,6 +662,10 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
return &job->common;
error:
if (copy_bitmap) {
assert(!job || !job->copy_bitmap);
hbitmap_free(copy_bitmap);
}
if (sync_bitmap) {
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
}