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>

drivers/md/dm-kcopyd.c

@@ -672,7 +672,8 @@ int dm_kcopyd_client_create(unsigned int nr_pages,
 		goto bad_slab;
 
 	INIT_WORK(&kc->kcopyd_work, do_work);
-	kc->kcopyd_wq = alloc_ordered_workqueue("kcopyd", WQ_MEM_RECLAIM);
+	kc->kcopyd_wq = alloc_workqueue("kcopyd",
+					WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
 	if (!kc->kcopyd_wq)
 		goto bad_workqueue;
 

drivers/md/dm-raid1.c

@@ -1085,7 +1085,8 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_requests = 1;
 	ti->num_discard_requests = 1;
 
-	ms->kmirrord_wq = alloc_ordered_workqueue("kmirrord", WQ_MEM_RECLAIM);
+	ms->kmirrord_wq = alloc_workqueue("kmirrord",
+					  WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
 	if (!ms->kmirrord_wq) {
 		DMERR("couldn't start kmirrord");
 		r = -ENOMEM;
@@ -1414,7 +1415,7 @@ static int mirror_iterate_devices(struct dm_target *ti,
 
 static struct target_type mirror_target = {
 	.name	 = "mirror",
-	.version = {1, 12, 0},
+	.version = {1, 12, 1},
 	.module	 = THIS_MODULE,
 	.ctr	 = mirror_ctr,
 	.dtr	 = mirror_dtr,

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;
 

include/linux/dm-ioctl.h

@@ -268,8 +268,8 @@ enum {
 
 #define DM_VERSION_MAJOR	4
 #define DM_VERSION_MINOR	19
-#define DM_VERSION_PATCHLEVEL	0
-#define DM_VERSION_EXTRA	"-ioctl (2010-10-14)"
+#define DM_VERSION_PATCHLEVEL	1
+#define DM_VERSION_EXTRA	"-ioctl (2011-01-07)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */