From e5863d9ad754926e7d3f38b43ac8bd48ef73b097 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 17 Dec 2014 21:08:12 -0500 Subject: dm: allocate requests in target when stacking on blk-mq devices For blk-mq request-based DM the responsibility of allocating a cloned request is transfered from DM core to the target type. Doing so enables the cloned request to be allocated from the appropriate blk-mq request_queue's pool (only the DM target, e.g. multipath, can know which block device to send a given cloned request to). Care was taken to preserve compatibility with old-style block request completion that requires request-based DM _not_ acquire the clone request's queue lock in the completion path. As such, there are now 2 different request-based DM target_type interfaces: 1) the original .map_rq() interface will continue to be used for non-blk-mq devices -- the preallocated clone request is passed in from DM core. 2) a new .clone_and_map_rq() and .release_clone_rq() will be used for blk-mq devices -- blk_get_request() and blk_put_request() are used respectively from these hooks. dm_table_set_type() was updated to detect if the request-based target is being stacked on blk-mq devices, if so DM_TYPE_MQ_REQUEST_BASED is set. DM core disallows switching the DM table's type after it is set. This means that there is no mixing of non-blk-mq and blk-mq devices within the same request-based DM table. [This patch was started by Keith and later heavily modified by Mike] Tested-by: Bart Van Assche Signed-off-by: Keith Busch Signed-off-by: Mike Snitzer --- drivers/md/dm-table.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 3afae9e..2d7e373 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -827,6 +827,7 @@ static int dm_table_set_type(struct dm_table *t) { unsigned i; unsigned bio_based = 0, request_based = 0, hybrid = 0; + bool use_blk_mq = false; struct dm_target *tgt; struct dm_dev_internal *dd; struct list_head *devices; @@ -872,11 +873,26 @@ static int dm_table_set_type(struct dm_table *t) /* Non-request-stackable devices can't be used for request-based dm */ devices = dm_table_get_devices(t); list_for_each_entry(dd, devices, list) { - if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev->bdev))) { - DMWARN("table load rejected: including" - " non-request-stackable devices"); + struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev); + + if (!blk_queue_stackable(q)) { + DMERR("table load rejected: including" + " non-request-stackable devices"); return -EINVAL; } + + if (q->mq_ops) + use_blk_mq = true; + } + + if (use_blk_mq) { + /* verify _all_ devices in the table are blk-mq devices */ + list_for_each_entry(dd, devices, list) + if (!bdev_get_queue(dd->dm_dev->bdev)->mq_ops) { + DMERR("table load rejected: not all devices" + " are blk-mq request-stackable"); + return -EINVAL; + } } /* @@ -890,7 +906,7 @@ static int dm_table_set_type(struct dm_table *t) return -EINVAL; } - t->type = DM_TYPE_REQUEST_BASED; + t->type = !use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED; return 0; } @@ -907,7 +923,15 @@ struct target_type *dm_table_get_immutable_target_type(struct dm_table *t) bool dm_table_request_based(struct dm_table *t) { - return dm_table_get_type(t) == DM_TYPE_REQUEST_BASED; + unsigned table_type = dm_table_get_type(t); + + return (table_type == DM_TYPE_REQUEST_BASED || + table_type == DM_TYPE_MQ_REQUEST_BASED); +} + +bool dm_table_mq_request_based(struct dm_table *t) +{ + return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED; } static int dm_table_alloc_md_mempools(struct dm_table *t) -- cgit v1.1