[PATCH] block: fix trace completion for chained bio
DORMANTno replies
REVIEWED: 2 (0M)
From: edwardh <hidden>
Date: 2020-12-08 06:04:31
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
2 review trailers.
From: Edward Hsieh <redacted>
For chained bio, trace_block_bio_complete in bio_endio is called only by
the parent bio once upon all chained bio completed. However, the sector and
the size for the parent bio are modified in bio_split. Therefore,
the size of the complete events might not match the queue events.
The original fix of bio completion trace <fbbaf700e7b1> ("block: trace
completion of all bios.") wants multiple complete events to correspond
to one queue event but missed this.
md/raid5 read with bio cross chunks can reproduce this issue.
To fix, move trace completion into the loop for every chained bio to call.
Fixes: fbbaf700e7b1 ("block: trace completion of all bios.")
Reviewed-by: Wade Liang <redacted>
Reviewed-by: BingJing Chang <redacted>
Signed-off-by: Edward Hsieh <redacted>
---
block/bio.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index fa01bef3..d202d6b 100644
--- a/block/bio.c
+++ b/block/bio.c@@ -1411,8 +1411,7 @@ static inline bool bio_remaining_done(struct bio *bio) * * bio_endio() can be called several times on a bio that has been chained * using bio_chain(). The ->bi_end_io() function will only be called the - * last time. At this point the BLK_TA_COMPLETE tracing event will be - * generated if BIO_TRACE_COMPLETION is set. + * last time. **/ void bio_endio(struct bio *bio) {
@@ -1425,6 +1424,11 @@ void bio_endio(struct bio *bio) if (bio->bi_disk) rq_qos_done_bio(bio->bi_disk->queue, bio); + if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) { + trace_block_bio_complete(bio->bi_disk->queue, bio); + bio_clear_flag(bio, BIO_TRACE_COMPLETION); + } + /* * Need to have a real endio function for chained bios, otherwise * various corner cases will break (like stacking block devices that
@@ -1438,11 +1442,6 @@ void bio_endio(struct bio *bio) goto again; } - if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) { - trace_block_bio_complete(bio->bi_disk->queue, bio); - bio_clear_flag(bio, BIO_TRACE_COMPLETION); - } - blk_throtl_bio_endio(bio); /* release cgroup info */ bio_uninit(bio);
--
2.7.4