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bcache: fix wrong cache_misses statistics 

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>
This commit is contained in:
tang.junhui 2017-10-30 14:46:34 -07:00 committed by Jens Axboe
parent d44c2f9e7c
commit c157313791
1 changed files with 5 additions and 1 deletions
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6
drivers/md/bcache/request.c
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@ -470,6 +470,7 @@ struct search {
unsigned recoverable:1;
unsigned write:1;
unsigned read_dirty_data:1;
unsigned cache_missed:1;
unsigned long start_time;
@ -656,6 +657,7 @@ static inline struct search *search_alloc(struct bio *bio,
s->orig_bio = bio;
s->cache_miss = NULL;
s->cache_missed = 0;
s->d = d;
s->recoverable = 1;
s->write = op_is_write(bio_op(bio));
@ -775,7 +777,7 @@ static void cached_dev_read_done_bh(struct closure *cl)
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.status)
@ -794,6 +796,8 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
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;