[dm-devel] [PATCH v2 7/9] dm: improve noclone_endio() to support multipath target
Mike Snitzer
snitzer at redhat.com
Wed Feb 20 21:44:34 UTC 2019
noclone_endio() must call the target's ->endio method if it exists.
Also must handle the various DM_ENDIO_* returns that are possible.
Factor out dm_bio_pushback_needed() for both dec_pending() and
noclone_endio() to use when handling BLK_STS_DM_REQUEUE.
Lastly, there is no need to conditionally set md->immutable_target in
__bind(). If the device only uses a single immutable target then it
should always be reflected in md->immutable_target. This is important
because noclone_endio() benefits from this to get access to the
multipath dm_target without needing to add another member to the
'dm_noclone' structure.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm.c | 80 ++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 57 insertions(+), 23 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 7e022f840419..0943913bceca 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -919,6 +919,28 @@ static int __noflush_suspending(struct mapped_device *md)
return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
}
+static bool dm_bio_pushback_needed(struct mapped_device *md,
+ struct bio *bio, blk_status_t *error)
+{
+ unsigned long flags;
+
+ /*
+ * Target requested pushing back the I/O.
+ */
+ if (__noflush_suspending(md)) {
+ spin_lock_irqsave(&md->deferred_lock, flags);
+ // FIXME: using bio_list_add_head() creates LIFO
+ bio_list_add_head(&md->deferred, bio);
+ spin_unlock_irqrestore(&md->deferred_lock, flags);
+ return true;
+ } else {
+ /* noflush suspend was interrupted. */
+ *error = BLK_STS_IOERR;
+ }
+
+ return false;
+}
+
/*
* Decrements the number of outstanding ios that a bio has been
* cloned into, completing the original io if necc.
@@ -939,22 +961,12 @@ static void dec_pending(struct dm_io *io, blk_status_t error)
}
if (atomic_dec_and_test(&io->io_count)) {
- if (io->status == BLK_STS_DM_REQUEUE) {
- /*
- * Target requested pushing back the I/O.
- */
- spin_lock_irqsave(&md->deferred_lock, flags);
- if (__noflush_suspending(md))
- /* NOTE early return due to BLK_STS_DM_REQUEUE below */
- bio_list_add_head(&md->deferred, io->orig_bio);
- else
- /* noflush suspend was interrupted. */
- io->status = BLK_STS_IOERR;
- spin_unlock_irqrestore(&md->deferred_lock, flags);
- }
+ bio = io->orig_bio;
+
+ if (unlikely(io->status == BLK_STS_DM_REQUEUE))
+ (void) dm_bio_pushback_needed(md, bio, &io->status);
io_error = io->status;
- bio = io->orig_bio;
if (unlikely(dm_stats_used(&md->stats))) {
unsigned long duration = jiffies - io->start_time;
@@ -1041,8 +1053,33 @@ static void clone_endio(struct bio *bio)
static void noclone_endio(struct bio *bio)
{
+ blk_status_t error = bio->bi_status;
struct dm_noclone *noclone = bio->bi_private;
struct mapped_device *md = noclone->md;
+ struct dm_target *ti = NULL;
+ dm_endio_fn endio = NULL;
+
+ if (md->immutable_target) {
+ ti = md->immutable_target;
+ endio = ti->type->end_io;
+ }
+
+ if (endio) {
+ int r = endio(ti, bio, &error);
+ switch (r) {
+ case DM_ENDIO_REQUEUE:
+ error = BLK_STS_DM_REQUEUE;
+ /*FALLTHRU*/
+ case DM_ENDIO_DONE:
+ break;
+ case DM_ENDIO_INCOMPLETE:
+ /* The target will handle the io */
+ return;
+ default:
+ DMWARN("unimplemented target endio return value: %d", r);
+ BUG();
+ }
+ }
end_io_acct(md, bio, noclone->start_time);
@@ -1050,6 +1087,11 @@ static void noclone_endio(struct bio *bio)
bio->bi_private = noclone->orig_bi_private;
kfree(noclone);
+ if (unlikely(error == BLK_STS_DM_REQUEUE)) {
+ if (dm_bio_pushback_needed(md, bio, &bio->bi_status))
+ return;
+ }
+
bio_endio(bio);
}
@@ -2249,15 +2291,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
if (request_based)
dm_stop_queue(q);
- if (request_based || md->type == DM_TYPE_NVME_BIO_BASED) {
- /*
- * Leverage the fact that request-based DM targets and
- * NVMe bio based targets are immutable singletons
- * - used to optimize both dm_request_fn and dm_mq_queue_rq;
- * and __process_bio.
- */
- md->immutable_target = dm_table_get_immutable_target(t);
- }
+ md->immutable_target = dm_table_get_immutable_target(t);
ret = __bind_mempools(md, t);
if (ret) {
--
2.15.0
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