1 files changed, 54 insertions, 3 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 36a8fc059ac3..9f01870d031c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -870,6 +870,44 @@ do_sync_io:
         pr_debug("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
 }
 
+struct raid1_plug_cb {
+        struct blk_plug_cb      cb;
+        struct bio_list         pending;
+        int                     pending_cnt;
+};
+
+static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
+{
+        struct raid1_plug_cb *plug = container_of(cb, struct raid1_plug_cb,
+                                                  cb);
+        struct mddev *mddev = plug->cb.data;
+        struct r1conf *conf = mddev->private;
+        struct bio *bio;
+
+        if (from_schedule) {
+                spin_lock_irq(&conf->device_lock);
+                bio_list_merge(&conf->pending_bio_list, &plug->pending);
+                conf->pending_count += plug->pending_cnt;
+                spin_unlock_irq(&conf->device_lock);
+                md_wakeup_thread(mddev->thread);
+                kfree(plug);
+                return;
+        }
+
+        /* we aren't scheduling, so we can do the write-out directly. */
+        bio = bio_list_get(&plug->pending);
+        bitmap_unplug(mddev->bitmap);
+        wake_up(&conf->wait_barrier);
+
+        while (bio) { /* submit pending writes */
+                struct bio *next = bio->bi_next;
+                bio->bi_next = NULL;
+                generic_make_request(bio);
+                bio = next;
+        }
+        kfree(plug);
+}
+
 static void make_request(struct mddev *mddev, struct bio * bio)
 {
         struct r1conf *conf = mddev->private;
@@ -883,6 +921,8 @@ static void make_request(struct mddev *mddev, struct bio * bio)
         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
         const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
         struct md_rdev *blocked_rdev;
+        struct blk_plug_cb *cb;
+        struct raid1_plug_cb *plug = NULL;
         int first_clone;
         int sectors_handled;
         int max_sectors;
@@ -1185,11 +1225,22 @@ read_again:
                 mbio->bi_private = r1_bio;
 
                 atomic_inc(&r1_bio->remaining);
+
+                cb = blk_check_plugged(raid1_unplug, mddev, sizeof(*plug));
+                if (cb)
+                        plug = container_of(cb, struct raid1_plug_cb, cb);
+                else
+                        plug = NULL;
                 spin_lock_irqsave(&conf->device_lock, flags);
-                bio_list_add(&conf->pending_bio_list, mbio);
-                conf->pending_count++;
+                if (plug) {
+                        bio_list_add(&plug->pending, mbio);
+                        plug->pending_cnt++;
+                } else {
+                        bio_list_add(&conf->pending_bio_list, mbio);
+                        conf->pending_count++;
+                }
                 spin_unlock_irqrestore(&conf->device_lock, flags);
-                if (!mddev_check_plugged(mddev))
+                if (!plug)
                         md_wakeup_thread(mddev->thread);
         }
         /* Mustn't call r1_bio_write_done before this next test,