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;a=summary
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@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Dec 18 15:03:25 CET 2017
From: "tang.junhui" <tang.junhui@xxxxxxxxxx>
Date: Mon, 30 Oct 2017 14:46:34 -0700
Subject: bcache: fix wrong cache_misses statistics
From: "tang.junhui" <tang.junhui@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Reviewed-by: Michael Lyle <mlyle@xxxxxxxx>
Reviewed-by: Coly Li <colyli@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx are
queue-3.18/bcache-fix-wrong-cache_misses-statistics.patch