1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6081941de1b3..4070eff6f0f8 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -315,10 +315,11 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                 if (r1_bio->bios[mirror] == bio)
                         break;
 
-        if (error == -ENOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
+        if (error == -EOPNOTSUPP && test_bit(R1BIO_Barrier, &r1_bio->state)) {
                 set_bit(BarriersNotsupp, &conf->mirrors[mirror].rdev->flags);
                 set_bit(R1BIO_BarrierRetry, &r1_bio->state);
                 r1_bio->mddev->barriers_work = 0;
+                /* Don't rdev_dec_pending in this branch - keep it for the retry */
         } else {
                 /*
                  * this branch is our 'one mirror IO has finished' event handler:
@@ -365,6 +366,7 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                                 }
                         }
                 }
+                rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
         }
         /*
          *
@@ -374,11 +376,9 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
         if (atomic_dec_and_test(&r1_bio->remaining)) {
                 if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
                         reschedule_retry(r1_bio);
-                        /* Don't dec_pending yet, we want to hold
-                         * the reference over the retry
-                         */
                         goto out;
                 }
+                /* it really is the end of this request */
                 if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
                         /* free extra copy of the data pages */
                         int i = bio->bi_vcnt;
@@ -393,8 +393,6 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                 md_write_end(r1_bio->mddev);
                 raid_end_bio_io(r1_bio);
         }
-
-        rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
  out:
         if (to_put)
                 bio_put(to_put);
@@ -753,18 +751,24 @@ static int make_request(request_queue_t *q, struct bio * bio)
         const int rw = bio_data_dir(bio);
         int do_barriers;
 
-        if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
-                bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
-                return 0;
-        }
-
         /*
          * Register the new request and wait if the reconstruction
          * thread has put up a bar for new requests.
          * Continue immediately if no resync is active currently.
+         * We test barriers_work *after* md_write_start as md_write_start
+         * may cause the first superblock write, and that will check out
+         * if barriers work.
          */
+
         md_write_start(mddev, bio); /* wait on superblock update early */
 
+        if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
+                if (rw == WRITE)
+                        md_write_end(mddev);
+                bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+                return 0;
+        }
+
         wait_barrier(conf);
 
         disk_stat_inc(mddev->gendisk, ios[rw]);
@@ -1404,10 +1408,11 @@ static void raid1d(mddev_t *mddev)
                         unplug = 1;
                 } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
                         /* some requests in the r1bio were BIO_RW_BARRIER
-                         * requests which failed with -ENOTSUPP.  Hohumm..
+                         * requests which failed with -EOPNOTSUPP.  Hohumm..
                          * Better resubmit without the barrier.
                          * We know which devices to resubmit for, because
                          * all others have had their bios[] entry cleared.
+                         * We already have a nr_pending reference on these rdevs.
                          */
                         int i;
                         clear_bit(R1BIO_BarrierRetry, &r1_bio->state);