From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Of course, QEMU_ALIGN_UP is a typo, it should be QEMU_ALIGN_DOWN, as we
are trying to find aligned size which satisfy both source and target.
Also, don't ignore too small max_transfer. In this case seems safer to
disable copy_range.
Fixes: 9ded4a0114968e
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190920142056.12778-2-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/backup.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/block/backup.c b/block/backup.c
index 763f0d7ff6..db20249063 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -741,12 +741,19 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
job->cluster_size = cluster_size;
job->copy_bitmap = copy_bitmap;
copy_bitmap = NULL;
- job->use_copy_range = !compress; /* compression isn't supported for it */
job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk),
blk_get_max_transfer(job->target));
- job->copy_range_size = MAX(job->cluster_size,
- QEMU_ALIGN_UP(job->copy_range_size,
- job->cluster_size));
+ job->copy_range_size = QEMU_ALIGN_DOWN(job->copy_range_size,
+ job->cluster_size);
+ /*
+ * Set use_copy_range, consider the following:
+ * 1. Compression is not supported for copy_range.
+ * 2. copy_range does not respect max_transfer (it's a TODO), so we factor
+ * that in here. If max_transfer is smaller than the job->cluster_size,
+ * we do not use copy_range (in that case it's zero after aligning down
+ * above).
+ */
+ job->use_copy_range = !compress && job->copy_range_size > 0;
/* Required permissions are already taken with target's blk_new() */
block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
--
2.21.0