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dm: improve BLK_STS_DM_REQUEUE and BLK_STS_AGAIN handling

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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 <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Ming Lei 2022-06-24 22:12:53 +08:00 committed by Mike Snitzer
parent e810cb78bc
commit 444fe04f7a
1 changed files with 45 additions and 25 deletions
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76
drivers/md/dm.c
View file

@ -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)
{
blk_status_t io_error;
struct mapped_device *md = io->md;
struct bio *bio = io->split_bio ? io->split_bio : io->orig_bio;
if (io->status == BLK_STS_DM_REQUEUE) {
unsigned long flags;
/*
* Target requested pushing back the I/O.
* 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)
{
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 (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 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 early if the original bio was requeued */
if (requeued)
return;
}
}
if (io_error == BLK_STS_DM_REQUEUE)
return;
}
if (bio_is_flush_with_data(bio)) {
/*