Hi Jens and Neil, Is there any feedback on this patch?
Thank you, Edward Hsieh On 3/3/2021 11:22 AM, Edward Hsieh wrote:
From: Edward Hsieh <edwa...@synology.com> For chained bio, trace_block_bio_complete in bio_endio is currently called only by the parent bio once upon all chained bio completed. However, the sector and size for the parent bio are modified in bio_split. Therefore, the size and sector of the complete events might not match the queue events in blktrace. 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 <wa...@synology.com> Reviewed-by: BingJing Chang <bingji...@synology.com> Signed-off-by: Edward Hsieh <edwa...@synology.com> --- block/bio.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/block/bio.c b/block/bio.c index a1c4d29..2ff72cb 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1397,8 +1397,7 @@ 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) { @@ -1411,6 +1410,11 @@ void bio_endio(struct bio *bio) if (bio->bi_bdev) rq_qos_done_bio(bio->bi_bdev->bd_disk->queue, bio);+ if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {+ trace_block_bio_complete(bio->bi_bdev->bd_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 @@ -1424,11 +1428,6 @@ void bio_endio(struct bio *bio) goto again; }- if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) {- trace_block_bio_complete(bio->bi_bdev->bd_disk->queue, bio); - bio_clear_flag(bio, BIO_TRACE_COMPLETION); - } - blk_throtl_bio_endio(bio); /* release cgroup info */ bio_uninit(bio);
