From 444fe04f7a5a7991daa1a8fc3680670ac87fc2ce Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 24 Jun 2022 22:12:53 +0800 Subject: [PATCH] dm: improve BLK_STS_DM_REQUEUE and BLK_STS_AGAIN handling If either BLK_STS_DM_REQUEUE or BLK_STS_AGAIN is returned for POLLED io, we requeue the original bio into deferred list and kick md->wq to re-submit it to block layer. Improve the handling in the following way: 1) Factor out dm_handle_requeue() for handling dm_io requeue. 2) Unify handling for BLK_STS_DM_REQUEUE and BLK_STS_AGAIN: clear REQ_POLLED for BLK_STS_DM_REQUEUE too, for the sake of simplicity, given BLK_STS_DM_REQUEUE is very unusual. 3) Queue md->wq explicitly in dm_handle_requeue(), so requeue handling becomes more robust. Signed-off-by: Ming Lei Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 70 ++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 45 insertions(+), 25 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 84929bd137d0..c987f9ad24a4 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -880,22 +880,41 @@ static int __noflush_suspending(struct mapped_device *md) return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags); } -static void dm_io_complete(struct dm_io *io) +/* + * Return true if the dm_io's original bio is requeued. + * io->status is updated with error if requeue disallowed. + */ +static bool dm_handle_requeue(struct dm_io *io) { - blk_status_t io_error; - struct mapped_device *md = io->md; struct bio *bio = io->split_bio ? io->split_bio : io->orig_bio; + bool handle_requeue = (io->status == BLK_STS_DM_REQUEUE); + bool handle_polled_eagain = ((io->status == BLK_STS_AGAIN) && + (bio->bi_opf & REQ_POLLED)); + struct mapped_device *md = io->md; + bool requeued = false; - if (io->status == BLK_STS_DM_REQUEUE) { + if (handle_requeue || handle_polled_eagain) { unsigned long flags; + + if (bio->bi_opf & REQ_POLLED) { + /* + * Upper layer won't help us poll split bio + * (io->orig_bio may only reflect a subset of the + * pre-split original) so clear REQ_POLLED. + */ + bio_clear_polled(bio); + } + /* - * Target requested pushing back the I/O. + * Target requested pushing back the I/O or + * polled IO hit BLK_STS_AGAIN. */ spin_lock_irqsave(&md->deferred_lock, flags); - if (__noflush_suspending(md) && - !WARN_ON_ONCE(dm_is_zone_write(md, bio))) { - /* NOTE early return due to BLK_STS_DM_REQUEUE below */ + if ((__noflush_suspending(md) && + !WARN_ON_ONCE(dm_is_zone_write(md, bio))) || + handle_polled_eagain) { bio_list_add_head(&md->deferred, bio); + requeued = true; } else { /* * noflush suspend was interrupted or this is @@ -906,6 +925,21 @@ static void dm_io_complete(struct dm_io *io) spin_unlock_irqrestore(&md->deferred_lock, flags); } + if (requeued) + queue_work(md->wq, &md->work); + + return requeued; +} + +static void dm_io_complete(struct dm_io *io) +{ + struct bio *bio = io->split_bio ? io->split_bio : io->orig_bio; + struct mapped_device *md = io->md; + blk_status_t io_error; + bool requeued; + + requeued = dm_handle_requeue(io); + io_error = io->status; if (dm_io_flagged(io, DM_IO_ACCOUNTED)) dm_end_io_acct(io); @@ -925,23 +959,9 @@ static void dm_io_complete(struct dm_io *io) if (unlikely(wq_has_sleeper(&md->wait))) wake_up(&md->wait); - if (io_error == BLK_STS_DM_REQUEUE || io_error == BLK_STS_AGAIN) { - if (bio->bi_opf & REQ_POLLED) { - /* - * Upper layer won't help us poll split bio (io->orig_bio - * may only reflect a subset of the pre-split original) - * so clear REQ_POLLED in case of requeue. - */ - bio_clear_polled(bio); - if (io_error == BLK_STS_AGAIN) { - /* io_uring doesn't handle BLK_STS_AGAIN (yet) */ - queue_io(md, bio); - return; - } - } - if (io_error == BLK_STS_DM_REQUEUE) - return; - } + /* Return early if the original bio was requeued */ + if (requeued) + return; if (bio_is_flush_with_data(bio)) { /* -- 2.11.0