[PATCH 4/5] bcache: fix wrong cache_misses statistics
From: Michael Lyle <hidden>
Date: 2017-10-30 21:47:00
Also in:
linux-bcache
Subsystem:
bcache (block layer cache), the rest · Maintainers:
Coly Li, Kent Overstreet, Linus Torvalds
From: "tang.junhui" <redacted> 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 <redacted> Reviewed-by: Michael Lyle <redacted> Reviewed-by: Coly Li <redacted> --- drivers/md/bcache/request.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 886e4b6643f1..597dd1e87bea 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c@@ -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;
--
2.11.0