dm: update targets using system workqueues to use a local workqueue

Flushing system-wide workqueues is dangerous and will be forbidden.
Use a local workqueue in dm-mpath.c, dm-raid1.c, and dm-stripe.c.

Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Author: Tetsuo Handa

drivers/md/dm-mpath.c

@@ -28,6 +28,8 @@
 #include <linux/atomic.h>
 #include <linux/blk-mq.h>
 
+static struct workqueue_struct *dm_mpath_wq;
+
 #define DM_MSG_PREFIX "multipath"
 #define DM_PG_INIT_DELAY_MSECS 2000
 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned int) -1)
@@ -1353,7 +1355,7 @@ static int fail_path(struct pgpath *pgpath)
 	dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
 		       pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
 
-	schedule_work(&m->trigger_event);
+	queue_work(dm_mpath_wq, &m->trigger_event);
 
 	enable_nopath_timeout(m);
 
@@ -2205,12 +2207,11 @@ static struct target_type multipath_target = {
 
 static int __init dm_multipath_init(void)
 {
-	int r;
+	int r = -ENOMEM;
 
 	kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
 	if (!kmultipathd) {
 		DMERR("failed to create workqueue kmpathd");
-		r = -ENOMEM;
 		goto bad_alloc_kmultipathd;
 	}
 
@@ -2224,10 +2225,15 @@ static int __init dm_multipath_init(void)
 						  WQ_MEM_RECLAIM);
 	if (!kmpath_handlerd) {
 		DMERR("failed to create workqueue kmpath_handlerd");
-		r = -ENOMEM;
 		goto bad_alloc_kmpath_handlerd;
 	}
 
+	dm_mpath_wq = alloc_workqueue("dm_mpath_wq", 0, 0);
+	if (!dm_mpath_wq) {
+		DMERR("failed to create workqueue dm_mpath_wq");
+		goto bad_alloc_dm_mpath_wq;
+	}
+
 	r = dm_register_target(&multipath_target);
 	if (r < 0) {
 		DMERR("request-based register failed %d", r);
@@ -2238,6 +2244,8 @@ static int __init dm_multipath_init(void)
 	return 0;
 
 bad_register_target:
+	destroy_workqueue(dm_mpath_wq);
+bad_alloc_dm_mpath_wq:
 	destroy_workqueue(kmpath_handlerd);
 bad_alloc_kmpath_handlerd:
 	destroy_workqueue(kmultipathd);
@@ -2247,6 +2255,7 @@ static int __init dm_multipath_init(void)
 
 static void __exit dm_multipath_exit(void)
 {
+	destroy_workqueue(dm_mpath_wq);
 	destroy_workqueue(kmpath_handlerd);
 	destroy_workqueue(kmultipathd);
 

drivers/md/dm-raid1.c

@@ -20,6 +20,8 @@
 #include <linux/dm-kcopyd.h>
 #include <linux/dm-region-hash.h>
 
+static struct workqueue_struct *dm_raid1_wq;
+
 #define DM_MSG_PREFIX "raid1"
 
 #define MAX_RECOVERY 1	/* Maximum number of regions recovered in parallel. */
@@ -251,7 +253,7 @@ static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
 		DMWARN("All sides of mirror have failed.");
 
 out:
-	schedule_work(&ms->trigger_event);
+	queue_work(dm_raid1_wq, &ms->trigger_event);
 }
 
 static int mirror_flush(struct dm_target *ti)
@@ -1496,22 +1498,28 @@ static struct target_type mirror_target = {
 
 static int __init dm_mirror_init(void)
 {
-	int r;
+	int r = -ENOMEM;
+
+	dm_raid1_wq = alloc_workqueue("dm_raid1_wq", 0, 0);
+	if (!dm_raid1_wq)
+		goto bad_target;
 
 	r = dm_register_target(&mirror_target);
 	if (r < 0) {
-		DMERR("Failed to register mirror target");
+		destroy_workqueue(dm_raid1_wq);
 		goto bad_target;
 	}
 
 	return 0;
 
 bad_target:
+	DMERR("Failed to register mirror target");
 	return r;
 }
 
 static void __exit dm_mirror_exit(void)
 {
+	destroy_workqueue(dm_raid1_wq);
 	dm_unregister_target(&mirror_target);
 }
 

drivers/md/dm-stripe.c

@@ -16,6 +16,8 @@
 #include <linux/slab.h>
 #include <linux/log2.h>
 
+static struct workqueue_struct *dm_stripe_wq;
+
 #define DM_MSG_PREFIX "striped"
 #define DM_IO_ERROR_THRESHOLD 15
 
@@ -428,7 +430,7 @@ static int stripe_end_io(struct dm_target *ti, struct bio *bio,
 			atomic_inc(&(sc->stripe[i].error_count));
 			if (atomic_read(&(sc->stripe[i].error_count)) <
 			    DM_IO_ERROR_THRESHOLD)
-				schedule_work(&sc->trigger_event);
+				queue_work(dm_stripe_wq, &sc->trigger_event);
 		}
 
 	return DM_ENDIO_DONE;
@@ -481,14 +483,20 @@ int __init dm_stripe_init(void)
 {
 	int r;
 
+	dm_stripe_wq = alloc_workqueue("dm_stripe_wq", 0, 0);
+	if (!dm_stripe_wq)
+		return -ENOMEM;
 	r = dm_register_target(&stripe_target);
-	if (r < 0)
+	if (r < 0) {
+		destroy_workqueue(dm_stripe_wq);
 		DMWARN("target registration failed");
+	}
 
 	return r;
 }
 
 void dm_stripe_exit(void)
 {
 	dm_unregister_target(&stripe_target);
+	destroy_workqueue(dm_stripe_wq);
 }