Commit 85750aeb748f ("bcache: use bio_{start,end}_io_acct") moves the io account code to the location after bio_set_dev(bio, dc->bdev) in cached_dev_make_request(). Then the account is performed incorrectly on backing device, indeed the I/O should be counted to bcache device like /dev/bcache0.

With the mistaken I/O account, iostat does not display I/O counts for bcache device and all the numbers go to backing device. In writeback mode, the hard drive may have 340K+ IOPS which is impossible and wrong for spinning disk.

This patch introduces bch_bio_start_io_acct() and bch_bio_end_io_acct(), which switches bio->bi_disk to bcache device before calling bio_start_io_acct() or bio_end_io_acct(). Now the I/Os are counted to bcache device, and bcache device, cache device and backing device have their correct I/O count information back.

Fixes: 85750aeb748f ("bcache: use bio_{start,end}_io_acct") Signed-off-by: Coly Li colyli@suse.de Cc: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org --- drivers/md/bcache/request.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c index 7acf024e99f3..8ea0f079c1d0 100644 --- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -617,6 +617,28 @@ static void cache_lookup(struct closure *cl)

/* Common code for the make_request functions */

+static inline void bch_bio_start_io_acct(struct gendisk *acct_bi_disk, + struct bio *bio, + unsigned long *start_time) +{ + struct gendisk *saved_bi_disk = bio->bi_disk; + + bio->bi_disk = acct_bi_disk; + *start_time = bio_start_io_acct(bio); + bio->bi_disk = saved_bi_disk; +} + +static inline void bch_bio_end_io_acct(struct gendisk *acct_bi_disk, + struct bio *bio, + unsigned long start_time) +{ + struct gendisk *saved_bi_disk = bio->bi_disk; + + bio->bi_disk = acct_bi_disk; + bio_end_io_acct(bio, start_time); + bio->bi_disk = saved_bi_disk; +} + static void request_endio(struct bio *bio) { struct closure *cl = bio->bi_private; @@ -668,7 +690,7 @@ static void backing_request_endio(struct bio *bio) static void bio_complete(struct search *s) { if (s->orig_bio) { - bio_end_io_acct(s->orig_bio, s->start_time); + bch_bio_end_io_acct(s->d->disk, s->orig_bio, s->start_time); trace_bcache_request_end(s->d, s->orig_bio); s->orig_bio->bi_status = s->iop.status; bio_endio(s->orig_bio); @@ -728,7 +750,7 @@ static inline struct search *search_alloc(struct bio *bio, s->recoverable = 1; s->write = op_is_write(bio_op(bio)); s->read_dirty_data = 0; - s->start_time = bio_start_io_acct(bio); + bch_bio_start_io_acct(d->disk, bio, &s->start_time);

s->iop.c = d->c; s->iop.bio = NULL; @@ -1080,7 +1102,7 @@ static void detached_dev_end_io(struct bio *bio) bio->bi_end_io = ddip->bi_end_io; bio->bi_private = ddip->bi_private;

- bio_end_io_acct(bio, ddip->start_time); + bch_bio_end_io_acct(ddip->d->disk, bio, ddip->start_time);

if (bio->bi_status) { struct cached_dev *dc = container_of(ddip->d, @@ -1105,7 +1127,8 @@ static void detached_dev_do_request(struct bcache_device *d, struct bio *bio) */ ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO); ddip->d = d; - ddip->start_time = bio_start_io_acct(bio); + bch_bio_start_io_acct(d->disk, bio, &ddip->start_time); + ddip->bi_end_io = bio->bi_end_io; ddip->bi_private = bio->bi_private; bio->bi_end_io = detached_dev_end_io;