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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>
This commit is contained in:
Mike Snitzer 2017-12-11 11:02:29 -05:00
parent 848b8aefd4
commit 0001ec565d
1 changed files with 56 additions and 14 deletions
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70
drivers/md/dm-mpath.c
View File

@ -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;