Discard is a special type of request that can have non-contiguous bios. Imagine we have a request with starting sector 0 and length 1024, so read or write means [0, 1024) range in the file. For discard this request can have 2 bios [0, 512) and [1024, 1536), but we always discarded [0, 1024). Set max_discard_segments to 1 to avoid such merges.
https://virtuozzo.atlassian.net/browse/VSTOR-154159 Fixes: 222b6f1291c1 ("dm-qcow2: Introduce driver to create block devices over QCOW2 files") Feature: dm-qcow2: block device over QCOW2 files driver Signed-off-by: Andrey Zhadchenko <[email protected]> --- drivers/md/dm-qcow2-target.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/md/dm-qcow2-target.c b/drivers/md/dm-qcow2-target.c index 7c572bd66e1ca..8337efc5c6238 100644 --- a/drivers/md/dm-qcow2-target.c +++ b/drivers/md/dm-qcow2-target.c @@ -1053,6 +1053,7 @@ static void qcow2_io_hints(struct dm_target *ti, struct queue_limits *limits) */ limits->discard_granularity = sb->s_blocksize; limits->max_hw_discard_sectors = to_sector(qcow2->clu_size); + limits->max_discard_segments = 1; limits->logical_block_size = block_size; limits->physical_block_size = block_size; -- 2.43.5 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
