Commit 2c6e755b authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm writecache: count number of blocks read, not number of read bios 



Change dm-writecache, so that it counts the number of blocks read
instead of the number of read bios. Bios can be split and requeued
using the dm_accept_partial_bio function, so counting bios caused
inaccurate results.

Fixes: e3a35d03 ("dm writecache: add event counters")
Reported-by: default avatarYu Kuai <yukuai1@huaweicloud.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 9bc0c92e

Documentation/admin-guide/device-mapper/writecache.rst

+2 −2
Original line number Diff line number Diff line
@@ -80,8 +80,8 @@ Status: 
2. the number of blocks

3. the number of free blocks

4. the number of blocks under writeback

5. the number of read requests

6. the number of read requests that hit the cache

5. the number of read blocks

6. the number of read blocks that hit the cache

7. the number of write requests

8. the number of write requests that hit uncommitted block

9. the number of write requests that hit committed block

drivers/md/dm-writecache.c

+1 −0
Original line number Diff line number Diff line
@@ -1365,6 +1365,7 @@ static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio * 
		}

	} else {

		writecache_map_remap_origin(wc, bio, e);

		wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;

		map_op = WC_MAP_REMAP_ORIGIN;

	}