From: Ming Lei <ming.lei@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
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)) {
/*
--
2.15.0
