10 files changed, 122 insertions, 259 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index ba19060bcf3f..8a2f767f26d8 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -294,8 +294,8 @@ static int linear_make_request (mddev_t *mddev, struct bio *bio)
         dev_info_t *tmp_dev;
         sector_t start_sector;
 
-        if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-                md_barrier_request(mddev, bio);
+        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+                md_flush_request(mddev, bio);
                 return 0;
         }
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index c148b6302154..3640f025cb72 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -226,12 +226,12 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
                 return 0;
         }
         rcu_read_lock();
-        if (mddev->suspended || mddev->barrier) {
+        if (mddev->suspended) {
                 DEFINE_WAIT(__wait);
                 for (;;) {
                         prepare_to_wait(&mddev->sb_wait, &__wait,
                                         TASK_UNINTERRUPTIBLE);
-                        if (!mddev->suspended && !mddev->barrier)
+                        if (!mddev->suspended)
                                 break;
                         rcu_read_unlock();
                         schedule();
@@ -282,40 +282,29 @@ EXPORT_SYMBOL_GPL(mddev_resume);
 
 int mddev_congested(mddev_t *mddev, int bits)
 {
-        if (mddev->barrier)
-                return 1;
         return mddev->suspended;
 }
 EXPORT_SYMBOL(mddev_congested);
 
 /*
- * Generic barrier handling for md
+ * Generic flush handling for md
  */
 
-#define POST_REQUEST_BARRIER ((void*)1)
-
-static void md_end_barrier(struct bio *bio, int err)
+static void md_end_flush(struct bio *bio, int err)
 {
         mdk_rdev_t *rdev = bio->bi_private;
         mddev_t *mddev = rdev->mddev;
-        if (err == -EOPNOTSUPP && mddev->barrier != POST_REQUEST_BARRIER)
-                set_bit(BIO_EOPNOTSUPP, &mddev->barrier->bi_flags);
 
         rdev_dec_pending(rdev, mddev);
 
         if (atomic_dec_and_test(&mddev->flush_pending)) {
-                if (mddev->barrier == POST_REQUEST_BARRIER) {
-                        /* This was a post-request barrier */
-                        mddev->barrier = NULL;
-                        wake_up(&mddev->sb_wait);
-                } else
-                        /* The pre-request barrier has finished */
-                        schedule_work(&mddev->barrier_work);
+                /* The pre-request flush has finished */
+                schedule_work(&mddev->flush_work);
         }
         bio_put(bio);
 }
 
-static void submit_barriers(mddev_t *mddev)
+static void submit_flushes(mddev_t *mddev)
 {
         mdk_rdev_t *rdev;
 
@@ -332,60 +321,56 @@ static void submit_barriers(mddev_t *mddev)
                         atomic_inc(&rdev->nr_pending);
                         rcu_read_unlock();
                         bi = bio_alloc(GFP_KERNEL, 0);
-                        bi->bi_end_io = md_end_barrier;
+                        bi->bi_end_io = md_end_flush;
                         bi->bi_private = rdev;
                         bi->bi_bdev = rdev->bdev;
                         atomic_inc(&mddev->flush_pending);
-                        submit_bio(WRITE_BARRIER, bi);
+                        submit_bio(WRITE_FLUSH, bi);
                         rcu_read_lock();
                         rdev_dec_pending(rdev, mddev);
                 }
         rcu_read_unlock();
 }
 
-static void md_submit_barrier(struct work_struct *ws)
+static void md_submit_flush_data(struct work_struct *ws)
 {
-        mddev_t *mddev = container_of(ws, mddev_t, barrier_work);
-        struct bio *bio = mddev->barrier;
+        mddev_t *mddev = container_of(ws, mddev_t, flush_work);
+        struct bio *bio = mddev->flush_bio;
 
         atomic_set(&mddev->flush_pending, 1);
 
-        if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
-                bio_endio(bio, -EOPNOTSUPP);
-        else if (bio->bi_size == 0)
+        if (bio->bi_size == 0)
                 /* an empty barrier - all done */
                 bio_endio(bio, 0);
         else {
-                bio->bi_rw &= ~REQ_HARDBARRIER;
+                bio->bi_rw &= ~REQ_FLUSH;
                 if (mddev->pers->make_request(mddev, bio))
                         generic_make_request(bio);
-                mddev->barrier = POST_REQUEST_BARRIER;
-                submit_barriers(mddev);
         }
         if (atomic_dec_and_test(&mddev->flush_pending)) {
-                mddev->barrier = NULL;
+                mddev->flush_bio = NULL;
                 wake_up(&mddev->sb_wait);
         }
 }
 
-void md_barrier_request(mddev_t *mddev, struct bio *bio)
+void md_flush_request(mddev_t *mddev, struct bio *bio)
 {
         spin_lock_irq(&mddev->write_lock);
         wait_event_lock_irq(mddev->sb_wait,
-                            !mddev->barrier,
+                            !mddev->flush_bio,
                             mddev->write_lock, /*nothing*/);
-        mddev->barrier = bio;
+        mddev->flush_bio = bio;
         spin_unlock_irq(&mddev->write_lock);
 
         atomic_set(&mddev->flush_pending, 1);
-        INIT_WORK(&mddev->barrier_work, md_submit_barrier);
+        INIT_WORK(&mddev->flush_work, md_submit_flush_data);
 
-        submit_barriers(mddev);
+        submit_flushes(mddev);
 
         if (atomic_dec_and_test(&mddev->flush_pending))
-                schedule_work(&mddev->barrier_work);
+                schedule_work(&mddev->flush_work);
 }
-EXPORT_SYMBOL(md_barrier_request);
+EXPORT_SYMBOL(md_flush_request);
 
 /* Support for plugging.
  * This mirrors the plugging support in request_queue, but does not
@@ -696,31 +681,6 @@ static void super_written(struct bio *bio, int error)
         bio_put(bio);
 }
 
-static void super_written_barrier(struct bio *bio, int error)
-{
-        struct bio *bio2 = bio->bi_private;
-        mdk_rdev_t *rdev = bio2->bi_private;
-        mddev_t *mddev = rdev->mddev;
-
-        if (!test_bit(BIO_UPTODATE, &bio->bi_flags) &&
-            error == -EOPNOTSUPP) {
-                unsigned long flags;
-                /* barriers don't appear to be supported :-( */
-                set_bit(BarriersNotsupp, &rdev->flags);
-                mddev->barriers_work = 0;
-                spin_lock_irqsave(&mddev->write_lock, flags);
-                bio2->bi_next = mddev->biolist;
-                mddev->biolist = bio2;
-                spin_unlock_irqrestore(&mddev->write_lock, flags);
-                wake_up(&mddev->sb_wait);
-                bio_put(bio);
-        } else {
-                bio_put(bio2);
-                bio->bi_private = rdev;
-                super_written(bio, error);
-        }
-}
-
 void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
                    sector_t sector, int size, struct page *page)
 {
@@ -729,51 +689,28 @@ void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
          * and decrement it on completion, waking up sb_wait
          * if zero is reached.
          * If an error occurred, call md_error
-         *
-         * As we might need to resubmit the request if REQ_HARDBARRIER
-         * causes ENOTSUPP, we allocate a spare bio...
          */
         struct bio *bio = bio_alloc(GFP_NOIO, 1);
-        int rw = REQ_WRITE | REQ_SYNC | REQ_UNPLUG;
 
         bio->bi_bdev = rdev->bdev;
         bio->bi_sector = sector;
         bio_add_page(bio, page, size, 0);
         bio->bi_private = rdev;
         bio->bi_end_io = super_written;
-        bio->bi_rw = rw;
 
         atomic_inc(&mddev->pending_writes);
-        if (!test_bit(BarriersNotsupp, &rdev->flags)) {
-                struct bio *rbio;
-                rw |= REQ_HARDBARRIER;
-                rbio = bio_clone(bio, GFP_NOIO);
-                rbio->bi_private = bio;
-                rbio->bi_end_io = super_written_barrier;
-                submit_bio(rw, rbio);
-        } else
-                submit_bio(rw, bio);
+        submit_bio(REQ_WRITE | REQ_SYNC | REQ_UNPLUG | REQ_FLUSH | REQ_FUA,
+                   bio);
 }
 
 void md_super_wait(mddev_t *mddev)
 {
-        /* wait for all superblock writes that were scheduled to complete.
-         * if any had to be retried (due to BARRIER problems), retry them
-         */
+        /* wait for all superblock writes that were scheduled to complete */
         DEFINE_WAIT(wq);
         for(;;) {
                 prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
                 if (atomic_read(&mddev->pending_writes)==0)
                         break;
-                while (mddev->biolist) {
-                        struct bio *bio;
-                        spin_lock_irq(&mddev->write_lock);
-                        bio = mddev->biolist;
-                        mddev->biolist = bio->bi_next ;
-                        bio->bi_next = NULL;
-                        spin_unlock_irq(&mddev->write_lock);
-                        submit_bio(bio->bi_rw, bio);
-                }
                 schedule();
         }
         finish_wait(&mddev->sb_wait, &wq);
@@ -1070,7 +1007,6 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
         clear_bit(Faulty, &rdev->flags);
         clear_bit(In_sync, &rdev->flags);
         clear_bit(WriteMostly, &rdev->flags);
-        clear_bit(BarriersNotsupp, &rdev->flags);
 
         if (mddev->raid_disks == 0) {
                 mddev->major_version = 0;
@@ -1485,7 +1421,6 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
         clear_bit(Faulty, &rdev->flags);
         clear_bit(In_sync, &rdev->flags);
         clear_bit(WriteMostly, &rdev->flags);
-        clear_bit(BarriersNotsupp, &rdev->flags);
 
         if (mddev->raid_disks == 0) {
                 mddev->major_version = 1;
@@ -4506,7 +4441,6 @@ int md_run(mddev_t *mddev)
         /* may be over-ridden by personality */
         mddev->resync_max_sectors = mddev->dev_sectors;
 
-        mddev->barriers_work = 1;
         mddev->ok_start_degraded = start_dirty_degraded;
 
         if (start_readonly && mddev->ro == 0)
@@ -4685,7 +4619,6 @@ static void md_clean(mddev_t *mddev)
         mddev->recovery = 0;
         mddev->in_sync = 0;
         mddev->degraded = 0;
-        mddev->barriers_work = 0;
         mddev->safemode = 0;
         mddev->bitmap_info.offset = 0;
         mddev->bitmap_info.default_offset = 0;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index a953fe2808ae..d8e2ab25103b 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -87,7 +87,6 @@ struct mdk_rdev_s
 #define Faulty          1               /* device is known to have a fault */
 #define In_sync         2               /* device is in_sync with rest of array */
 #define WriteMostly     4               /* Avoid reading if at all possible */
-#define BarriersNotsupp 5               /* REQ_HARDBARRIER is not supported */
 #define AllReserved     6               /* If whole device is reserved for
                                          * one array */
 #define AutoDetected    7               /* added by auto-detect */
@@ -273,13 +272,6 @@ struct mddev_s
         int                             degraded;       /* whether md should consider
                                                          * adding a spare
                                                          */
-        int                             barriers_work;  /* initialised to true, cleared as soon
-                                                         * as a barrier request to slave
-                                                         * fails.  Only supported
-                                                         */
-        struct bio                      *biolist;       /* bios that need to be retried
-                                                         * because REQ_HARDBARRIER is not supported
-                                                         */
 
         atomic_t                        recovery_active; /* blocks scheduled, but not written */
         wait_queue_head_t               recovery_wait;
@@ -339,16 +331,13 @@ struct mddev_s
         struct attribute_group          *to_remove;
         struct plug_handle              *plug; /* if used by personality */
 
-        /* Generic barrier handling.
-         * If there is a pending barrier request, all other
-         * writes are blocked while the devices are flushed.
-         * The last to finish a flush schedules a worker to
-         * submit the barrier request (without the barrier flag),
-         * then submit more flush requests.
+        /* Generic flush handling.
+         * The last to finish preflush schedules a worker to submit
+         * the rest of the request (without the REQ_FLUSH flag).
          */
-        struct bio *barrier;
+        struct bio *flush_bio;
         atomic_t flush_pending;
-        struct work_struct barrier_work;
+        struct work_struct flush_work;
         struct work_struct event_work;  /* used by dm to report failure event */
 };
 
@@ -502,7 +491,7 @@ extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 
 extern int mddev_congested(mddev_t *mddev, int bits);
-extern void md_barrier_request(mddev_t *mddev, struct bio *bio);
+extern void md_flush_request(mddev_t *mddev, struct bio *bio);
 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
                            sector_t sector, int size, struct page *page);
 extern void md_super_wait(mddev_t *mddev);
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 0307d217e7a4..6d7ddf32ef2e 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -142,8 +142,8 @@ static int multipath_make_request(mddev_t *mddev, struct bio * bio)
         struct multipath_bh * mp_bh;
         struct multipath_info *multipath;
 
-        if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-                md_barrier_request(mddev, bio);
+        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+                md_flush_request(mddev, bio);
                 return 0;
         }
 
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 6f7af46d623c..a39f4c355e55 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -483,8 +483,8 @@ static int raid0_make_request(mddev_t *mddev, struct bio *bio)
         struct strip_zone *zone;
         mdk_rdev_t *tmp_dev;
 
-        if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-                md_barrier_request(mddev, bio);
+        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+                md_flush_request(mddev, bio);
                 return 0;
         }
 
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ad83a4dcadc3..886a9d865488 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -319,83 +319,74 @@ static void raid1_end_write_request(struct bio *bio, int error)
                 if (r1_bio->bios[mirror] == bio)
                         break;
 
-        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 {
+        /*
+         * 'one mirror IO has finished' event handler:
+         */
+        r1_bio->bios[mirror] = NULL;
+        to_put = bio;
+        if (!uptodate) {
+                md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
+                /* an I/O failed, we can't clear the bitmap */
+                set_bit(R1BIO_Degraded, &r1_bio->state);
+        } else
                 /*
-                 * this branch is our 'one mirror IO has finished' event handler:
+                 * Set R1BIO_Uptodate in our master bio, so that we
+                 * will return a good error code for to the higher
+                 * levels even if IO on some other mirrored buffer
+                 * fails.
+                 *
+                 * The 'master' represents the composite IO operation
+                 * to user-side. So if something waits for IO, then it
+                 * will wait for the 'master' bio.
                  */
-                r1_bio->bios[mirror] = NULL;
-                to_put = bio;
-                if (!uptodate) {
-                        md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
-                        /* an I/O failed, we can't clear the bitmap */
-                        set_bit(R1BIO_Degraded, &r1_bio->state);
-                } else
-                        /*
-                         * Set R1BIO_Uptodate in our master bio, so that
-                         * we will return a good error code for to the higher
-                         * levels even if IO on some other mirrored buffer fails.
-                         *
-                         * The 'master' represents the composite IO operation to
-                         * user-side. So if something waits for IO, then it will
-                         * wait for the 'master' bio.
-                         */
-                        set_bit(R1BIO_Uptodate, &r1_bio->state);
-
-                update_head_pos(mirror, r1_bio);
-
-                if (behind) {
-                        if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
-                                atomic_dec(&r1_bio->behind_remaining);
-
-                        /* In behind mode, we ACK the master bio once the I/O has safely
-                         * reached all non-writemostly disks. Setting the Returned bit
-                         * ensures that this gets done only once -- we don't ever want to
-                         * return -EIO here, instead we'll wait */
-
-                        if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
-                            test_bit(R1BIO_Uptodate, &r1_bio->state)) {
-                                /* Maybe we can return now */
-                                if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
-                                        struct bio *mbio = r1_bio->master_bio;
-                                        PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
-                                               (unsigned long long) mbio->bi_sector,
-                                               (unsigned long long) mbio->bi_sector +
-                                               (mbio->bi_size >> 9) - 1);
-                                        bio_endio(mbio, 0);
-                                }
+                set_bit(R1BIO_Uptodate, &r1_bio->state);
+
+        update_head_pos(mirror, r1_bio);
+
+        if (behind) {
+                if (test_bit(WriteMostly, &conf->mirrors[mirror].rdev->flags))
+                        atomic_dec(&r1_bio->behind_remaining);
+
+                /*
+                 * In behind mode, we ACK the master bio once the I/O
+                 * has safely reached all non-writemostly
+                 * disks. Setting the Returned bit ensures that this
+                 * gets done only once -- we don't ever want to return
+                 * -EIO here, instead we'll wait
+                 */
+                if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
+                    test_bit(R1BIO_Uptodate, &r1_bio->state)) {
+                        /* Maybe we can return now */
+                        if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
+                                struct bio *mbio = r1_bio->master_bio;
+                                PRINTK(KERN_DEBUG "raid1: behind end write sectors %llu-%llu\n",
+                                       (unsigned long long) mbio->bi_sector,
+                                       (unsigned long long) mbio->bi_sector +
+                                       (mbio->bi_size >> 9) - 1);
+                                bio_endio(mbio, 0);
                         }
                 }
-                rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
         }
+        rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
+
         /*
-         *
          * Let's see if all mirrored write operations have finished
          * already.
          */
         if (atomic_dec_and_test(&r1_bio->remaining)) {
-                if (test_bit(R1BIO_BarrierRetry, &r1_bio->state))
-                        reschedule_retry(r1_bio);
-                else {
-                        /* 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;
-                                while (i--)
-                                        safe_put_page(bio->bi_io_vec[i].bv_page);
-                        }
-                        /* clear the bitmap if all writes complete successfully */
-                        bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
-                                        r1_bio->sectors,
-                                        !test_bit(R1BIO_Degraded, &r1_bio->state),
-                                        behind);
-                        md_write_end(r1_bio->mddev);
-                        raid_end_bio_io(r1_bio);
+                if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
+                        /* free extra copy of the data pages */
+                        int i = bio->bi_vcnt;
+                        while (i--)
+                                safe_put_page(bio->bi_io_vec[i].bv_page);
                 }
+                /* clear the bitmap if all writes complete successfully */
+                bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
+                                r1_bio->sectors,
+                                !test_bit(R1BIO_Degraded, &r1_bio->state),
+                                behind);
+                md_write_end(r1_bio->mddev);
+                raid_end_bio_io(r1_bio);
         }
 
         if (to_put)
@@ -788,16 +779,13 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         struct page **behind_pages = NULL;
         const int rw = bio_data_dir(bio);
         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
-        unsigned long do_barriers;
+        const unsigned long do_flush_fua = (bio->bi_rw & (REQ_FLUSH | REQ_FUA));
         mdk_rdev_t *blocked_rdev;
 
         /*
          * 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 */
@@ -821,13 +809,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
                 }
                 finish_wait(&conf->wait_barrier, &w);
         }
-        if (unlikely(!mddev->barriers_work &&
-                     (bio->bi_rw & REQ_HARDBARRIER))) {
-                if (rw == WRITE)
-                        md_write_end(mddev);
-                bio_endio(bio, -EOPNOTSUPP);
-                return 0;
-        }
 
         wait_barrier(conf);
 
@@ -959,10 +940,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         atomic_set(&r1_bio->remaining, 0);
         atomic_set(&r1_bio->behind_remaining, 0);
 
-        do_barriers = bio->bi_rw & REQ_HARDBARRIER;
-        if (do_barriers)
-                set_bit(R1BIO_Barrier, &r1_bio->state);
-
         bio_list_init(&bl);
         for (i = 0; i < disks; i++) {
                 struct bio *mbio;
@@ -975,7 +952,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
                 mbio->bi_sector = r1_bio->sector + conf->mirrors[i].rdev->data_offset;
                 mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
                 mbio->bi_end_io = raid1_end_write_request;
-                mbio->bi_rw = WRITE | do_barriers | do_sync;
+                mbio->bi_rw = WRITE | do_flush_fua | do_sync;
                 mbio->bi_private = r1_bio;
 
                 if (behind_pages) {
@@ -1634,41 +1611,6 @@ static void raid1d(mddev_t *mddev)
                 if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
                         sync_request_write(mddev, r1_bio);
                         unplug = 1;
-                } else if (test_bit(R1BIO_BarrierRetry, &r1_bio->state)) {
-                        /* some requests in the r1bio were REQ_HARDBARRIER
-                         * 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;
-                        const unsigned long do_sync = (r1_bio->master_bio->bi_rw & REQ_SYNC);
-                        clear_bit(R1BIO_BarrierRetry, &r1_bio->state);
-                        clear_bit(R1BIO_Barrier, &r1_bio->state);
-                        for (i=0; i < conf->raid_disks; i++)
-                                if (r1_bio->bios[i])
-                                        atomic_inc(&r1_bio->remaining);
-                        for (i=0; i < conf->raid_disks; i++)
-                                if (r1_bio->bios[i]) {
-                                        struct bio_vec *bvec;
-                                        int j;
-
-                                        bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
-                                        /* copy pages from the failed bio, as
-                                         * this might be a write-behind device */
-                                        __bio_for_each_segment(bvec, bio, j, 0)
-                                                bvec->bv_page = bio_iovec_idx(r1_bio->bios[i], j)->bv_page;
-                                        bio_put(r1_bio->bios[i]);
-                                        bio->bi_sector = r1_bio->sector +
-                                                conf->mirrors[i].rdev->data_offset;
-                                        bio->bi_bdev = conf->mirrors[i].rdev->bdev;
-                                        bio->bi_end_io = raid1_end_write_request;
-                                        bio->bi_rw = WRITE | do_sync;
-                                        bio->bi_private = r1_bio;
-                                        r1_bio->bios[i] = bio;
-                                        generic_make_request(bio);
-                                }
                 } else {
                         int disk;
 
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index 5f2d443ae28a..adf8cfd73313 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -117,8 +117,6 @@ struct r1bio_s {
 #define R1BIO_IsSync    1
 #define R1BIO_Degraded  2
 #define R1BIO_BehindIO  3
-#define R1BIO_Barrier   4
-#define R1BIO_BarrierRetry 5
 /* For write-behind requests, we call bi_end_io when
  * the last non-write-behind device completes, providing
  * any write was successful.  Otherwise we call when
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 84718383124d..f0d082f749be 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -800,12 +800,13 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         int chunk_sects = conf->chunk_mask + 1;
         const int rw = bio_data_dir(bio);
         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
+        const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
         struct bio_list bl;
         unsigned long flags;
         mdk_rdev_t *blocked_rdev;
 
-        if (unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
-                md_barrier_request(mddev, bio);
+        if (unlikely(bio->bi_rw & REQ_FLUSH)) {
+                md_flush_request(mddev, bio);
                 return 0;
         }
 
@@ -965,7 +966,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
                         conf->mirrors[d].rdev->data_offset;
                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
                 mbio->bi_end_io = raid10_end_write_request;
-                mbio->bi_rw = WRITE | do_sync;
+                mbio->bi_rw = WRITE | do_sync | do_fua;
                 mbio->bi_private = r10_bio;
 
                 atomic_inc(&r10_bio->remaining);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 69b0a169e43d..31140d1259dc 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -506,9 +506,12 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
                 int rw;
                 struct bio *bi;
                 mdk_rdev_t *rdev;
-                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags))
-                        rw = WRITE;
-                else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
+                if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
+                        if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
+                                rw = WRITE_FUA;
+                        else
+                                rw = WRITE;
+                } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
                         rw = READ;
                 else
                         continue;
@@ -1031,6 +1034,8 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
 
                         while (wbi && wbi->bi_sector <
                                 dev->sector + STRIPE_SECTORS) {
+                                if (wbi->bi_rw & REQ_FUA)
+                                        set_bit(R5_WantFUA, &dev->flags);
                                 tx = async_copy_data(1, wbi, dev->page,
                                         dev->sector, tx);
                                 wbi = r5_next_bio(wbi, dev->sector);
@@ -1048,15 +1053,22 @@ static void ops_complete_reconstruct(void *stripe_head_ref)
         int pd_idx = sh->pd_idx;
         int qd_idx = sh->qd_idx;
         int i;
+        bool fua = false;
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
 
+        for (i = disks; i--; )
+                fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
+
         for (i = disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
 
-                if (dev->written || i == pd_idx || i == qd_idx)
+                if (dev->written || i == pd_idx || i == qd_idx) {
                         set_bit(R5_UPTODATE, &dev->flags);
+                        if (fua)
+                                set_bit(R5_WantFUA, &dev->flags);
+                }
         }
 
         if (sh->reconstruct_state == reconstruct_state_drain_run)
@@ -3281,7 +3293,7 @@ static void handle_stripe5(struct stripe_head *sh)
 
         if (dec_preread_active) {
                 /* We delay this until after ops_run_io so that if make_request
-                 * is waiting on a barrier, it won't continue until the writes
+                 * is waiting on a flush, it won't continue until the writes
                  * have actually been submitted.
                  */
                 atomic_dec(&conf->preread_active_stripes);
@@ -3583,7 +3595,7 @@ static void handle_stripe6(struct stripe_head *sh)
 
         if (dec_preread_active) {
                 /* We delay this until after ops_run_io so that if make_request
-                 * is waiting on a barrier, it won't continue until the writes
+                 * is waiting on a flush, it won't continue until the writes
                  * have actually been submitted.
                  */
                 atomic_dec(&conf->preread_active_stripes);
@@ -3978,14 +3990,8 @@ static int make_request(mddev_t *mddev, struct bio * bi)
         const int rw = bio_data_dir(bi);
         int remaining;
 
-        if (unlikely(bi->bi_rw & REQ_HARDBARRIER)) {
-                /* Drain all pending writes.  We only really need
-                 * to ensure they have been submitted, but this is
-                 * easier.
-                 */
-                mddev->pers->quiesce(mddev, 1);
-                mddev->pers->quiesce(mddev, 0);
-                md_barrier_request(mddev, bi);
+        if (unlikely(bi->bi_rw & REQ_FLUSH)) {
+                md_flush_request(mddev, bi);
                 return 0;
         }
 
@@ -4103,7 +4109,7 @@ static int make_request(mddev_t *mddev, struct bio * bi)
                         finish_wait(&conf->wait_for_overlap, &w);
                         set_bit(STRIPE_HANDLE, &sh->state);
                         clear_bit(STRIPE_DELAYED, &sh->state);
-                        if (mddev->barrier && 
+                        if ((bi->bi_rw & REQ_SYNC) &&
                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
                                 atomic_inc(&conf->preread_active_stripes);
                         release_stripe(sh);
@@ -4126,13 +4132,6 @@ static int make_request(mddev_t *mddev, struct bio * bi)
                 bio_endio(bi, 0);
         }
 
-        if (mddev->barrier) {
-                /* We need to wait for the stripes to all be handled.
-                 * So: wait for preread_active_stripes to drop to 0.
-                 */
-                wait_event(mddev->thread->wqueue,
-                           atomic_read(&conf->preread_active_stripes) == 0);
-        }
         return 0;
 }
 
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 36eaed5dfd6e..2ace0582b409 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -275,6 +275,7 @@ struct r6_state {
                                     * filling
                                     */
 #define R5_Wantdrain    13 /* dev->towrite needs to be drained */
+#define R5_WantFUA      14      /* Write should be FUA */
 /*
  * Write method
  */