dm: use non reentrant workqueues if equivalent

kmirrord_wq, kcopyd_work and md->wq are created per dm instance and
serve only a single work item from the dm instance, so non-reentrant
workqueues would provide the same ordering guarantees as ordered ones
while allowing CPU affinity and use of the workqueues for other
purposes.  Switch them to non-reentrant workqueues.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 39aaa9290128..e504bb40d60e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1883,7 +1883,8 @@ static struct mapped_device *alloc_dev(int minor)
         add_disk(md->disk);
         format_dev_t(md->name, MKDEV(_major, minor));
 
-        md->wq = alloc_ordered_workqueue("kdmflush", WQ_MEM_RECLAIM);
+        md->wq = alloc_workqueue("kdmflush",
+                                 WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
         if (!md->wq)
                 goto bad_thread;