From 2c6e755b49d273243431f5f1184654e71221fc78 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Mon, 11 Jul 2022 16:30:52 -0400
Subject: [PATCH] dm writecache: count number of blocks read, not number of
 read bios
Git-commit: 2c6e755b49d273243431f5f1184654e71221fc78
Patch-mainline: v6.0-rc1
References: jsc#PED-2765

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: Coly Li <colyli@suse.de>

---
 Documentation/admin-guide/device-mapper/writecache.rst | 4 ++--
 drivers/md/dm-writecache.c                             | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/device-mapper/writecache.rst b/Documentation/admin-guide/device-mapper/writecache.rst
index 2104812f0281..1fab82408ef1 100644
--- a/Documentation/admin-guide/device-mapper/writecache.rst
+++ b/Documentation/admin-guide/device-mapper/writecache.rst
@@ -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
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 9e14717c46a9..a551be5f9b4b 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -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;
 	}
 
-- 
2.35.3