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dm: submit stacked requests in irq enabled context

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Switch to having request-based DM enqueue all prep'ed requests into work
processed by another thread.  This allows request-based DM to invoke
block APIs that assume interrupt enabled context (e.g. blk_get_request)
and is a prerequisite for adding blk-mq support to request-based DM.

The new kernel thread is only initialized for request-based DM devices.

multipath_map() is now always in irq enabled context so change multipath
spinlock (m->lock) locking to always disable interrupts.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Keith Busch
2014-10-17 17:46:36 -06:00
committed by Mike Snitzer
parent 1ae49ea2cf
commit 2eb6e1e3aa
2 changed files with 47 additions and 19 deletions
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drivers/md/dm-mpath.c
+12 -8
View File
@@ -384,12 +384,11 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
struct multipath *m = (struct multipath *) ti->private;
int r = DM_MAPIO_REQUEUE;
size_t nr_bytes = blk_rq_bytes(clone);
unsigned long flags;
struct pgpath *pgpath;
struct block_device *bdev;
struct dm_mpath_io *mpio;
spin_lock_irqsave(&m->lock, flags);
spin_lock_irq(&m->lock);
/* Do we need to select a new pgpath? */
if (!m->current_pgpath ||
@@ -411,21 +410,26 @@ static int multipath_map(struct dm_target *ti, struct request *clone,
/* ENOMEM, requeue */
goto out_unlock;
bdev = pgpath->path.dev->bdev;
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
mpio = map_context->ptr;
mpio->pgpath = pgpath;
mpio->nr_bytes = nr_bytes;
bdev = pgpath->path.dev->bdev;
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
spin_unlock_irq(&m->lock);
if (pgpath->pg->ps.type->start_io)
pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
&pgpath->path,
nr_bytes);
r = DM_MAPIO_REMAPPED;
return DM_MAPIO_REMAPPED;
out_unlock:
spin_unlock_irqrestore(&m->lock, flags);
spin_unlock_irq(&m->lock);
return r;
}