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

[ Upstream commit 2c6e755b49d273243431f5f1184654e71221fc78 ]

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: e3a35d03407c ("dm writecache: add event counters")
Reported-by: Yu Kuai <yukuai1@huaweicloud.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/Documentation/admin-guide/device-mapper/writecache.rst b/Documentation/admin-guide/device-mapper/writecache.rst
index 1042977..7bead3b 100644 (file)
--- a/Documentation/admin-guide/device-mapper/writecache.rst
+++ b/Documentation/admin-guide/device-mapper/writecache.rst
@@ -78,8 +78,8 @@ 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

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index e3d0a9b..9d6b7b7 100644 (file)
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -1364,6 +1364,7 @@ read_next_block:
                }
        } 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;
        }