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block: mark blk-mq devices as stackable 

Commit 4ee5eaf4 ("block: add a queue flag for request stacking support")
introduced the concept of "STACKABLE" and blk-mq devices fit the
definition in that they establish q->request_fn.  So establish
QUEUE_FLAG_STACKABLE in QUEUE_FLAG_MQ_DEFAULT.

While not strictly needed (DM _could_ just check for q->mq_ops to assume
the device is request-based), request-based DM support for blk-mq devices
benefits from the ability to consistently check for QUEUE_FLAG_STACKABLE
before allowing a device to be stacked into a request-based DM table.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Mike Snitzer 2014-12-16 12:54:25 -05:00 committed by Jens Axboe
parent 77a0868901
commit ad9cf3bbd1
1 changed files with 1 additions and 0 deletions
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include/linux/blkdev.h
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@ -520,6 +520,7 @@ struct request_queue {
(1 << QUEUE_FLAG_ADD_RANDOM))
#define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_STACKABLE) | \
(1 << QUEUE_FLAG_SAME_COMP))
static inline void queue_lockdep_assert_held(struct request_queue *q)