dm mpath: factor out SCSI vs NVMe path selection
Trying to do both SCSI and NVMe bio-based handling with branching in the
same common code has proven too tedious on a code maintenance level. In
addition it slightly hurts IO performance.
Fix this by factoring out __map_bio() and __map_bio_nvme().
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index fa5ee78..6d1a990 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -555,7 +555,8 @@ static void multipath_release_clone(struct request *clone)
/*
* Map cloned bios (bio-based multipath)
*/
-static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
+
+static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
{
struct pgpath *pgpath;
unsigned long flags;
@@ -563,31 +564,72 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
/* Do we need to select a new pgpath? */
pgpath = READ_ONCE(m->current_pgpath);
- /* MPATHF_QUEUE_IO will never be set for NVMe */
queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
if (!pgpath || !queue_io)
- pgpath = choose_pgpath(m, mpio->nr_bytes);
+ pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
- if ((!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
- (pgpath && queue_io)) {
+ if ((pgpath && queue_io) ||
+ (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
/* Queue for the daemon to resubmit */
spin_lock_irqsave(&m->lock, flags);
bio_list_add(&m->queued_bios, bio);
spin_unlock_irqrestore(&m->lock, flags);
- if (m->queue_mode == DM_TYPE_NVME_BIO_BASED) {
+ /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
+ if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
+ pg_init_all_paths(m);
+ else if (!queue_io)
queue_work(kmultipathd, &m->process_queued_bios);
- } else {
- /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
- if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
- pg_init_all_paths(m);
- else if (!queue_io)
- queue_work(kmultipathd, &m->process_queued_bios);
- }
- return DM_MAPIO_SUBMITTED;
+ return ERR_PTR(-EAGAIN);
}
+ return pgpath;
+}
+
+static struct pgpath *__map_bio_nvme(struct multipath *m, struct bio *bio)
+{
+ struct pgpath *pgpath;
+ unsigned long flags;
+
+ /* Do we need to select a new pgpath? */
+ /*
+ * FIXME: currently only switching path if no path (due to failure, etc)
+ * - which negates the point of using a path selector
+ */
+ pgpath = READ_ONCE(m->current_pgpath);
+ if (!pgpath)
+ pgpath = choose_pgpath(m, bio->bi_iter.bi_size);
+
+ if (!pgpath) {
+ if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
+ /* Queue for the daemon to resubmit */
+ spin_lock_irqsave(&m->lock, flags);
+ bio_list_add(&m->queued_bios, bio);
+ spin_unlock_irqrestore(&m->lock, flags);
+ queue_work(kmultipathd, &m->process_queued_bios);
+
+ return ERR_PTR(-EAGAIN);
+ }
+ return NULL;
+ }
+
+ return pgpath;
+}
+
+static int __multipath_map_bio(struct multipath *m, struct bio *bio,
+ struct dm_mpath_io *mpio)
+{
+ struct pgpath *pgpath;
+
+ if (m->queue_mode == DM_TYPE_NVME_BIO_BASED)
+ pgpath = __map_bio_nvme(m, bio);
+ else
+ pgpath = __map_bio(m, bio);
+
+ if (IS_ERR(pgpath))
+ return DM_MAPIO_SUBMITTED;
+
if (!pgpath) {
if (must_push_back_bio(m))
return DM_MAPIO_REQUEUE;