From 0001ec565db7ed01a6cc9575453900801bd0841b Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Mon, 11 Dec 2017 11:02:29 -0500 Subject: [PATCH] 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 --- drivers/md/dm-mpath.c | 68 +++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 55 insertions(+), 13 deletions(-) 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; @@ -563,30 +564,71 @@ 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 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)) -- 2.7.4