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@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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;
--
2.26.2
