This is a note to let you know that I've just added the patch titled

bcache: fix wrong cache_misses statistics

to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: bcache-fix-wrong-cache_misses-statistics.patch and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Mon Dec 18 15:03:25 CET 2017

From: "tang.junhui" tang.junhui@zte.com.cn Date: Mon, 30 Oct 2017 14:46:34 -0700 Subject: bcache: fix wrong cache_misses statistics

From: "tang.junhui" tang.junhui@zte.com.cn

[ Upstream commit c157313791a999646901b3e3c6888514ebc36d62 ]

Currently, Cache missed IOs are identified by s->cache_miss, but actually, there are many situations that missed IOs are not assigned a value for s->cache_miss in cached_dev_cache_miss(), for example, a bypassed IO (s->iop.bypass = 1), or the cache_bio allocate failed. In these situations, it will go to out_put or out_submit, and s->cache_miss is null, which leads bch_mark_cache_accounting() to treat this IO as a hit IO.

[ML: applied by 3-way merge]

Signed-off-by: tang.junhui tang.junhui@zte.com.cn Reviewed-by: Michael Lyle mlyle@lyle.org Reviewed-by: Coly Li colyli@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/bcache/request.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -464,6 +464,7 @@ struct search { unsigned recoverable:1; unsigned write:1; unsigned read_dirty_data:1; + unsigned cache_missed:1;

unsigned long start_time;

@@ -651,6 +652,7 @@ static inline struct search *search_allo

s->orig_bio = bio; s->cache_miss = NULL; + s->cache_missed = 0; s->d = d; s->recoverable = 1; s->write = (bio->bi_rw & REQ_WRITE) != 0; @@ -774,7 +776,7 @@ static void cached_dev_read_done_bh(stru struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);

bch_mark_cache_accounting(s->iop.c, s->d, - !s->cache_miss, s->iop.bypass); + !s->cache_missed, s->iop.bypass); trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);

if (s->iop.error) @@ -793,6 +795,8 @@ static int cached_dev_cache_miss(struct struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); struct bio *miss, *cache_bio;

+ s->cache_missed = 1; + if (s->cache_miss || s->iop.bypass) { miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split); ret = miss == bio ? MAP_DONE : MAP_CONTINUE;

Patches currently in stable-queue which might be from tang.junhui@zte.com.cn are

queue-3.18/bcache-fix-wrong-cache_misses-statistics.patch