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Commit c1573137 authored by tang.junhui's avatar tang.junhui Committed by Jens Axboe
Browse files

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: default avatartang.junhui <tang.junhui@zte.com.cn>
Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
Reviewed-by: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d44c2f9e

drivers/md/bcache/request.c

+5 −1
Original line number Diff line number Diff line
@@ -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;