From 8d47e65948ddea4398892946d9e50778a316b397 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Mon, 5 Mar 2018 14:10:11 -0500 Subject: [PATCH] dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks This eliminates the "queue_mode" configuration's "nvme" mode. There wasn't anything NVMe-specific about that mode. It was named "nvme" because it was a short name for the mode. But the entire point of the mode was to optimize the multipath target for underlying devices that are _not_ SCSI-based. Devices that aren't SCSI have no need for the various SCSI device handler (scsi_dh) specific code in DM multipath. But rather than narrowly define this scsi_dh vs not branching in terms of "nvme": invert the logic so that we're just checking whether a multipath device is layered on SCSI devices with scsi_dh attached. This allows any future storage technology to avoid scsi_dh specific code in the multipath target too. Fixes: 848b8aefd4 ("dm mpath: optimize NVMe bio-based support") Suggested-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-mpath.c | 66 ++++++++++++++++++++++----------------------------- 1 file changed, 29 insertions(+), 37 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 7d3e572..3fde9e9 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -211,25 +212,13 @@ static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m) else m->queue_mode = DM_TYPE_REQUEST_BASED; - } else if (m->queue_mode == DM_TYPE_BIO_BASED || - m->queue_mode == DM_TYPE_NVME_BIO_BASED) { + } else if (m->queue_mode == DM_TYPE_BIO_BASED) { INIT_WORK(&m->process_queued_bios, process_queued_bios); - - if (m->queue_mode == DM_TYPE_BIO_BASED) { - /* - * bio-based doesn't support any direct scsi_dh management; - * it just discovers if a scsi_dh is attached. - */ - set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags); - } - } - - if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) { - set_bit(MPATHF_QUEUE_IO, &m->flags); - atomic_set(&m->pg_init_in_progress, 0); - atomic_set(&m->pg_init_count, 0); - m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT; - init_waitqueue_head(&m->pg_init_wait); + /* + * bio-based doesn't support any direct scsi_dh management; + * it just discovers if a scsi_dh is attached. + */ + set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags); } dm_table_set_type(ti->table, m->queue_mode); @@ -337,14 +326,12 @@ static void __switch_pg(struct multipath *m, struct priority_group *pg) { m->current_pg = pg; - if (m->queue_mode == DM_TYPE_NVME_BIO_BASED) - return; - /* Must we initialise the PG first, and queue I/O till it's ready? */ if (m->hw_handler_name) { set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags); set_bit(MPATHF_QUEUE_IO, &m->flags); } else { + /* FIXME: not needed if no scsi_dh is attached */ clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags); clear_bit(MPATHF_QUEUE_IO, &m->flags); } @@ -385,8 +372,7 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes) unsigned bypassed = 1; if (!atomic_read(&m->nr_valid_paths)) { - if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) - clear_bit(MPATHF_QUEUE_IO, &m->flags); + clear_bit(MPATHF_QUEUE_IO, &m->flags); goto failed; } @@ -599,7 +585,7 @@ static struct pgpath *__map_bio(struct multipath *m, struct bio *bio) return pgpath; } -static struct pgpath *__map_bio_nvme(struct multipath *m, struct bio *bio) +static struct pgpath *__map_bio_fast(struct multipath *m, struct bio *bio) { struct pgpath *pgpath; unsigned long flags; @@ -634,8 +620,8 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, { struct pgpath *pgpath; - if (m->queue_mode == DM_TYPE_NVME_BIO_BASED) - pgpath = __map_bio_nvme(m, bio); + if (!m->hw_handler_name) + pgpath = __map_bio_fast(m, bio); else pgpath = __map_bio(m, bio); @@ -675,8 +661,7 @@ static void process_queued_io_list(struct multipath *m) { if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED) dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table)); - else if (m->queue_mode == DM_TYPE_BIO_BASED || - m->queue_mode == DM_TYPE_NVME_BIO_BASED) + else if (m->queue_mode == DM_TYPE_BIO_BASED) queue_work(kmultipathd, &m->process_queued_bios); } @@ -838,6 +823,16 @@ retain: */ kfree(m->hw_handler_name); m->hw_handler_name = attached_handler_name; + + /* + * Init fields that are only used when a scsi_dh is attached + */ + if (!test_and_set_bit(MPATHF_QUEUE_IO, &m->flags)) { + atomic_set(&m->pg_init_in_progress, 0); + atomic_set(&m->pg_init_count, 0); + m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT; + init_waitqueue_head(&m->pg_init_wait); + } } } @@ -873,6 +868,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps int r; struct pgpath *p; struct multipath *m = ti->private; + struct scsi_device *sdev; /* we need at least a path arg */ if (as->argc < 1) { @@ -891,7 +887,9 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps goto bad; } - if (m->queue_mode != DM_TYPE_NVME_BIO_BASED) { + sdev = scsi_device_from_queue(bdev_get_queue(p->path.dev->bdev)); + if (sdev) { + put_device(&sdev->sdev_gendev); INIT_DELAYED_WORK(&p->activate_path, activate_path_work); r = setup_scsi_dh(p->path.dev->bdev, m, &ti->error); if (r) { @@ -1001,8 +999,7 @@ static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m) if (!hw_argc) return 0; - if (m->queue_mode == DM_TYPE_BIO_BASED || - m->queue_mode == DM_TYPE_NVME_BIO_BASED) { + if (m->queue_mode == DM_TYPE_BIO_BASED) { dm_consume_args(as, hw_argc); DMERR("bio-based multipath doesn't allow hardware handler args"); return 0; @@ -1091,8 +1088,6 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m) if (!strcasecmp(queue_mode_name, "bio")) m->queue_mode = DM_TYPE_BIO_BASED; - else if (!strcasecmp(queue_mode_name, "nvme")) - m->queue_mode = DM_TYPE_NVME_BIO_BASED; else if (!strcasecmp(queue_mode_name, "rq")) m->queue_mode = DM_TYPE_REQUEST_BASED; else if (!strcasecmp(queue_mode_name, "mq")) @@ -1193,7 +1188,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv) ti->num_discard_bios = 1; ti->num_write_same_bios = 1; ti->num_write_zeroes_bios = 1; - if (m->queue_mode == DM_TYPE_BIO_BASED || m->queue_mode == DM_TYPE_NVME_BIO_BASED) + if (m->queue_mode == DM_TYPE_BIO_BASED) ti->per_io_data_size = multipath_per_bio_data_size(); else ti->per_io_data_size = sizeof(struct dm_mpath_io); @@ -1730,9 +1725,6 @@ static void multipath_status(struct dm_target *ti, status_type_t type, case DM_TYPE_BIO_BASED: DMEMIT("queue_mode bio "); break; - case DM_TYPE_NVME_BIO_BASED: - DMEMIT("queue_mode nvme "); - break; case DM_TYPE_MQ_REQUEST_BASED: DMEMIT("queue_mode mq "); break; -- 2.7.4