]> pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - drivers/md/raid1.c
Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6-omap-h63xx.git] / drivers / md / raid1.c
index e16f473bcf46b2bf1888eed7472c6474e4dc641e..a06ff91f27e2e6bb3af330e170faebdd79e6a9ce 100644 (file)
  */
 #define        NR_RAID1_BIOS 256
 
-static mdk_personality_t raid1_personality;
 
 static void unplug_slaves(mddev_t *mddev);
 
+static void allow_barrier(conf_t *conf);
+static void lower_barrier(conf_t *conf);
 
 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
 {
@@ -59,10 +60,8 @@ static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
        int size = offsetof(r1bio_t, bios[pi->raid_disks]);
 
        /* allocate a r1bio with room for raid_disks entries in the bios array */
-       r1_bio = kmalloc(size, gfp_flags);
-       if (r1_bio)
-               memset(r1_bio, 0, size);
-       else
+       r1_bio = kzalloc(size, gfp_flags);
+       if (!r1_bio)
                unplug_slaves(pi->mddev);
 
        return r1_bio;
@@ -104,15 +103,30 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
        }
        /*
         * Allocate RESYNC_PAGES data pages and attach them to
-        * the first bio;
+        * the first bio.
+        * If this is a user-requested check/repair, allocate
+        * RESYNC_PAGES for each bio.
         */
-       bio = r1_bio->bios[0];
-       for (i = 0; i < RESYNC_PAGES; i++) {
-               page = alloc_page(gfp_flags);
-               if (unlikely(!page))
-                       goto out_free_pages;
-
-               bio->bi_io_vec[i].bv_page = page;
+       if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
+               j = pi->raid_disks;
+       else
+               j = 1;
+       while(j--) {
+               bio = r1_bio->bios[j];
+               for (i = 0; i < RESYNC_PAGES; i++) {
+                       page = alloc_page(gfp_flags);
+                       if (unlikely(!page))
+                               goto out_free_pages;
+
+                       bio->bi_io_vec[i].bv_page = page;
+               }
+       }
+       /* If not user-requests, copy the page pointers to all bios */
+       if (!test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery)) {
+               for (i=0; i<RESYNC_PAGES ; i++)
+                       for (j=1; j<pi->raid_disks; j++)
+                               r1_bio->bios[j]->bi_io_vec[i].bv_page =
+                                       r1_bio->bios[0]->bi_io_vec[i].bv_page;
        }
 
        r1_bio->master_bio = NULL;
@@ -120,8 +134,10 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
        return r1_bio;
 
 out_free_pages:
-       for ( ; i > 0 ; i--)
-               __free_page(bio->bi_io_vec[i-1].bv_page);
+       for (i=0; i < RESYNC_PAGES ; i++)
+               for (j=0 ; j < pi->raid_disks; j++)
+                       safe_put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
+       j = -1;
 out_free_bio:
        while ( ++j < pi->raid_disks )
                bio_put(r1_bio->bios[j]);
@@ -132,14 +148,16 @@ out_free_bio:
 static void r1buf_pool_free(void *__r1_bio, void *data)
 {
        struct pool_info *pi = data;
-       int i;
+       int i,j;
        r1bio_t *r1bio = __r1_bio;
-       struct bio *bio = r1bio->bios[0];
 
-       for (i = 0; i < RESYNC_PAGES; i++) {
-               __free_page(bio->bi_io_vec[i].bv_page);
-               bio->bi_io_vec[i].bv_page = NULL;
-       }
+       for (i = 0; i < RESYNC_PAGES; i++)
+               for (j = pi->raid_disks; j-- ;) {
+                       if (j == 0 ||
+                           r1bio->bios[j]->bi_io_vec[i].bv_page !=
+                           r1bio->bios[0]->bi_io_vec[i].bv_page)
+                               safe_put_page(r1bio->bios[j]->bi_io_vec[i].bv_page);
+               }
        for (i=0 ; i < pi->raid_disks; i++)
                bio_put(r1bio->bios[i]);
 
@@ -152,7 +170,7 @@ static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 
        for (i = 0; i < conf->raid_disks; i++) {
                struct bio **bio = r1_bio->bios + i;
-               if (*bio)
+               if (*bio && *bio != IO_BLOCKED)
                        bio_put(*bio);
                *bio = NULL;
        }
@@ -160,20 +178,13 @@ static void put_all_bios(conf_t *conf, r1bio_t *r1_bio)
 
 static inline void free_r1bio(r1bio_t *r1_bio)
 {
-       unsigned long flags;
-
        conf_t *conf = mddev_to_conf(r1_bio->mddev);
 
        /*
         * Wake up any possible resync thread that waits for the device
         * to go idle.
         */
-       spin_lock_irqsave(&conf->resync_lock, flags);
-       if (!--conf->nr_pending) {
-               wake_up(&conf->wait_idle);
-               wake_up(&conf->wait_resume);
-       }
-       spin_unlock_irqrestore(&conf->resync_lock, flags);
+       allow_barrier(conf);
 
        put_all_bios(conf, r1_bio);
        mempool_free(r1_bio, conf->r1bio_pool);
@@ -182,22 +193,17 @@ static inline void free_r1bio(r1bio_t *r1_bio)
 static inline void put_buf(r1bio_t *r1_bio)
 {
        conf_t *conf = mddev_to_conf(r1_bio->mddev);
-       unsigned long flags;
+       int i;
 
-       mempool_free(r1_bio, conf->r1buf_pool);
+       for (i=0; i<conf->raid_disks; i++) {
+               struct bio *bio = r1_bio->bios[i];
+               if (bio->bi_end_io)
+                       rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
+       }
 
-       spin_lock_irqsave(&conf->resync_lock, flags);
-       if (!conf->barrier)
-               BUG();
-       --conf->barrier;
-       wake_up(&conf->wait_resume);
-       wake_up(&conf->wait_idle);
+       mempool_free(r1_bio, conf->r1buf_pool);
 
-       if (!--conf->nr_pending) {
-               wake_up(&conf->wait_idle);
-               wake_up(&conf->wait_resume);
-       }
-       spin_unlock_irqrestore(&conf->resync_lock, flags);
+       lower_barrier(conf);
 }
 
 static void reschedule_retry(r1bio_t *r1_bio)
@@ -208,8 +214,10 @@ static void reschedule_retry(r1bio_t *r1_bio)
 
        spin_lock_irqsave(&conf->device_lock, flags);
        list_add(&r1_bio->retry_list, &conf->retry_list);
+       conf->nr_queued ++;
        spin_unlock_irqrestore(&conf->device_lock, flags);
 
+       wake_up(&conf->wait_barrier);
        md_wakeup_thread(mddev->thread);
 }
 
@@ -261,9 +269,9 @@ static int raid1_end_read_request(struct bio *bio, unsigned int bytes_done, int
        /*
         * this branch is our 'one mirror IO has finished' event handler:
         */
-       if (!uptodate)
-               md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
-       else
+       update_head_pos(mirror, r1_bio);
+
+       if (uptodate || conf->working_disks <= 1) {
                /*
                 * Set R1BIO_Uptodate in our master bio, so that
                 * we will return a good error code for to the higher
@@ -273,16 +281,11 @@ static int raid1_end_read_request(struct bio *bio, unsigned int bytes_done, int
                 * 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 (uptodate)
+                       set_bit(R1BIO_Uptodate, &r1_bio->state);
 
-       /*
-        * we have only one bio on the read side
-        */
-       if (uptodate)
                raid_end_bio_io(r1_bio);
-       else {
+       else {
                /*
                 * oops, read error:
                 */
@@ -301,7 +304,7 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
 {
        int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
        r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
-       int mirror, behind;
+       int mirror, behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
        conf_t *conf = mddev_to_conf(r1_bio->mddev);
 
        if (bio->bi_size)
@@ -311,47 +314,53 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                if (r1_bio->bios[mirror] == bio)
                        break;
 
-       /*
-        * this branch is our 'one mirror IO has finished' event handler:
-        */
-       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
+       if (error == -ENOTSUPP && 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;
+       } 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.
+                * this branch is our 'one mirror IO has finished' event handler:
                 */
-               set_bit(R1BIO_Uptodate, &r1_bio->state);
-
-       update_head_pos(mirror, r1_bio);
-
-       behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
-       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, mbio->bi_size, 0);
+               r1_bio->bios[mirror] = NULL;
+               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, mbio->bi_size, 0);
+                               }
                        }
                }
        }
@@ -361,11 +370,18 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
         * already.
         */
        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
+                        */
+                       return 0;
+               }
                if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
                        /* free extra copy of the data pages */
                        int i = bio->bi_vcnt;
                        while (i--)
-                               __free_page(bio->bi_io_vec[i].bv_page);
+                               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,
@@ -376,6 +392,9 @@ static int raid1_end_write_request(struct bio *bio, unsigned int bytes_done, int
                raid_end_bio_io(r1_bio);
        }
 
+       if (r1_bio->bios[mirror]==NULL)
+               bio_put(bio);
+
        rdev_dec_pending(conf->mirrors[mirror].rdev, conf->mddev);
        return 0;
 }
@@ -416,12 +435,14 @@ static int read_balance(conf_t *conf, r1bio_t *r1_bio)
                /* Choose the first operation device, for consistancy */
                new_disk = 0;
 
-               for (rdev = conf->mirrors[new_disk].rdev;
-                    !rdev || !rdev->in_sync
+               for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
+                    r1_bio->bios[new_disk] == IO_BLOCKED ||
+                    !rdev || !test_bit(In_sync, &rdev->flags)
                             || test_bit(WriteMostly, &rdev->flags);
-                    rdev = conf->mirrors[++new_disk].rdev) {
+                    rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
 
-                       if (rdev && rdev->in_sync)
+                       if (rdev && test_bit(In_sync, &rdev->flags) &&
+                               r1_bio->bios[new_disk] != IO_BLOCKED)
                                wonly_disk = new_disk;
 
                        if (new_disk == conf->raid_disks - 1) {
@@ -434,12 +455,14 @@ static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 
 
        /* make sure the disk is operational */
-       for (rdev = conf->mirrors[new_disk].rdev;
-            !rdev || !rdev->in_sync ||
+       for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
+            r1_bio->bios[new_disk] == IO_BLOCKED ||
+            !rdev || !test_bit(In_sync, &rdev->flags) ||
                     test_bit(WriteMostly, &rdev->flags);
-            rdev = conf->mirrors[new_disk].rdev) {
+            rdev = rcu_dereference(conf->mirrors[new_disk].rdev)) {
 
-               if (rdev && rdev->in_sync)
+               if (rdev && test_bit(In_sync, &rdev->flags) &&
+                   r1_bio->bios[new_disk] != IO_BLOCKED)
                        wonly_disk = new_disk;
 
                if (new_disk <= 0)
@@ -474,10 +497,10 @@ static int read_balance(conf_t *conf, r1bio_t *r1_bio)
                        disk = conf->raid_disks;
                disk--;
 
-               rdev = conf->mirrors[disk].rdev;
+               rdev = rcu_dereference(conf->mirrors[disk].rdev);
 
-               if (!rdev ||
-                   !rdev->in_sync ||
+               if (!rdev || r1_bio->bios[disk] == IO_BLOCKED ||
+                   !test_bit(In_sync, &rdev->flags) ||
                    test_bit(WriteMostly, &rdev->flags))
                        continue;
 
@@ -496,15 +519,15 @@ static int read_balance(conf_t *conf, r1bio_t *r1_bio)
 
 
        if (new_disk >= 0) {
-               rdev = conf->mirrors[new_disk].rdev;
+               rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
                if (!rdev)
                        goto retry;
                atomic_inc(&rdev->nr_pending);
-               if (!rdev->in_sync) {
+               if (!test_bit(In_sync, &rdev->flags)) {
                        /* cannot risk returning a device that failed
                         * before we inc'ed nr_pending
                         */
-                       atomic_dec(&rdev->nr_pending);
+                       rdev_dec_pending(rdev, conf->mddev);
                        goto retry;
                }
                conf->next_seq_sect = this_sector + sectors;
@@ -522,8 +545,8 @@ static void unplug_slaves(mddev_t *mddev)
 
        rcu_read_lock();
        for (i=0; i<mddev->raid_disks; i++) {
-               mdk_rdev_t *rdev = conf->mirrors[i].rdev;
-               if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
+               mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
+               if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
                        request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
 
                        atomic_inc(&rdev->nr_pending);
@@ -556,8 +579,8 @@ static int raid1_issue_flush(request_queue_t *q, struct gendisk *disk,
 
        rcu_read_lock();
        for (i=0; i<mddev->raid_disks && ret == 0; i++) {
-               mdk_rdev_t *rdev = conf->mirrors[i].rdev;
-               if (rdev && !rdev->faulty) {
+               mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
+               if (rdev && !test_bit(Faulty, &rdev->flags)) {
                        struct block_device *bdev = rdev->bdev;
                        request_queue_t *r_queue = bdev_get_queue(bdev);
 
@@ -577,42 +600,119 @@ static int raid1_issue_flush(request_queue_t *q, struct gendisk *disk,
        return ret;
 }
 
-/*
- * Throttle resync depth, so that we can both get proper overlapping of
- * requests, but are still able to handle normal requests quickly.
+/* Barriers....
+ * Sometimes we need to suspend IO while we do something else,
+ * either some resync/recovery, or reconfigure the array.
+ * To do this we raise a 'barrier'.
+ * The 'barrier' is a counter that can be raised multiple times
+ * to count how many activities are happening which preclude
+ * normal IO.
+ * We can only raise the barrier if there is no pending IO.
+ * i.e. if nr_pending == 0.
+ * We choose only to raise the barrier if no-one is waiting for the
+ * barrier to go down.  This means that as soon as an IO request
+ * is ready, no other operations which require a barrier will start
+ * until the IO request has had a chance.
+ *
+ * So: regular IO calls 'wait_barrier'.  When that returns there
+ *    is no backgroup IO happening,  It must arrange to call
+ *    allow_barrier when it has finished its IO.
+ * backgroup IO calls must call raise_barrier.  Once that returns
+ *    there is no normal IO happeing.  It must arrange to call
+ *    lower_barrier when the particular background IO completes.
  */
 #define RESYNC_DEPTH 32
 
-static void device_barrier(conf_t *conf, sector_t sect)
+static void raise_barrier(conf_t *conf)
 {
        spin_lock_irq(&conf->resync_lock);
-       wait_event_lock_irq(conf->wait_idle, !waitqueue_active(&conf->wait_resume),
-                           conf->resync_lock, raid1_unplug(conf->mddev->queue));
-       
-       if (!conf->barrier++) {
-               wait_event_lock_irq(conf->wait_idle, !conf->nr_pending,
-                                   conf->resync_lock, raid1_unplug(conf->mddev->queue));
-               if (conf->nr_pending)
-                       BUG();
+
+       /* Wait until no block IO is waiting */
+       wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
+                           conf->resync_lock,
+                           raid1_unplug(conf->mddev->queue));
+
+       /* block any new IO from starting */
+       conf->barrier++;
+
+       /* No wait for all pending IO to complete */
+       wait_event_lock_irq(conf->wait_barrier,
+                           !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
+                           conf->resync_lock,
+                           raid1_unplug(conf->mddev->queue));
+
+       spin_unlock_irq(&conf->resync_lock);
+}
+
+static void lower_barrier(conf_t *conf)
+{
+       unsigned long flags;
+       spin_lock_irqsave(&conf->resync_lock, flags);
+       conf->barrier--;
+       spin_unlock_irqrestore(&conf->resync_lock, flags);
+       wake_up(&conf->wait_barrier);
+}
+
+static void wait_barrier(conf_t *conf)
+{
+       spin_lock_irq(&conf->resync_lock);
+       if (conf->barrier) {
+               conf->nr_waiting++;
+               wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
+                                   conf->resync_lock,
+                                   raid1_unplug(conf->mddev->queue));
+               conf->nr_waiting--;
        }
-       wait_event_lock_irq(conf->wait_resume, conf->barrier < RESYNC_DEPTH,
-                           conf->resync_lock, raid1_unplug(conf->mddev->queue));
-       conf->next_resync = sect;
+       conf->nr_pending++;
+       spin_unlock_irq(&conf->resync_lock);
+}
+
+static void allow_barrier(conf_t *conf)
+{
+       unsigned long flags;
+       spin_lock_irqsave(&conf->resync_lock, flags);
+       conf->nr_pending--;
+       spin_unlock_irqrestore(&conf->resync_lock, flags);
+       wake_up(&conf->wait_barrier);
+}
+
+static void freeze_array(conf_t *conf)
+{
+       /* stop syncio and normal IO and wait for everything to
+        * go quite.
+        * We increment barrier and nr_waiting, and then
+        * wait until barrier+nr_pending match nr_queued+2
+        */
+       spin_lock_irq(&conf->resync_lock);
+       conf->barrier++;
+       conf->nr_waiting++;
+       wait_event_lock_irq(conf->wait_barrier,
+                           conf->barrier+conf->nr_pending == conf->nr_queued+2,
+                           conf->resync_lock,
+                           raid1_unplug(conf->mddev->queue));
        spin_unlock_irq(&conf->resync_lock);
 }
+static void unfreeze_array(conf_t *conf)
+{
+       /* reverse the effect of the freeze */
+       spin_lock_irq(&conf->resync_lock);
+       conf->barrier--;
+       conf->nr_waiting--;
+       wake_up(&conf->wait_barrier);
+       spin_unlock_irq(&conf->resync_lock);
+}
+
 
 /* duplicate the data pages for behind I/O */
 static struct page **alloc_behind_pages(struct bio *bio)
 {
        int i;
        struct bio_vec *bvec;
-       struct page **pages = kmalloc(bio->bi_vcnt * sizeof(struct page *),
+       struct page **pages = kzalloc(bio->bi_vcnt * sizeof(struct page *),
                                        GFP_NOIO);
        if (unlikely(!pages))
                goto do_sync_io;
 
-       memset(pages, 0, bio->bi_vcnt * sizeof(struct page *));
-
        bio_for_each_segment(bvec, bio, i) {
                pages[i] = alloc_page(GFP_NOIO);
                if (unlikely(!pages[i]))
@@ -628,7 +728,7 @@ static struct page **alloc_behind_pages(struct bio *bio)
 do_sync_io:
        if (pages)
                for (i = 0; i < bio->bi_vcnt && pages[i]; i++)
-                       __free_page(pages[i]);
+                       put_page(pages[i]);
        kfree(pages);
        PRINTK("%dB behind alloc failed, doing sync I/O\n", bio->bi_size);
        return NULL;
@@ -648,8 +748,9 @@ static int make_request(request_queue_t *q, struct bio * bio)
        struct bio_list bl;
        struct page **behind_pages = NULL;
        const int rw = bio_data_dir(bio);
+       int do_barriers;
 
-       if (unlikely(bio_barrier(bio))) {
+       if (unlikely(!mddev->barriers_work && bio_barrier(bio))) {
                bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
                return 0;
        }
@@ -661,10 +762,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
         */
        md_write_start(mddev, bio); /* wait on superblock update early */
 
-       spin_lock_irq(&conf->resync_lock);
-       wait_event_lock_irq(conf->wait_resume, !conf->barrier, conf->resync_lock, );
-       conf->nr_pending++;
-       spin_unlock_irq(&conf->resync_lock);
+       wait_barrier(conf);
 
        disk_stat_inc(mddev->gendisk, ios[rw]);
        disk_stat_add(mddev->gendisk, sectors[rw], bio_sectors(bio));
@@ -728,11 +826,11 @@ static int make_request(request_queue_t *q, struct bio * bio)
 #endif
        rcu_read_lock();
        for (i = 0;  i < disks; i++) {
-               if ((rdev=conf->mirrors[i].rdev) != NULL &&
-                   !rdev->faulty) {
+               if ((rdev=rcu_dereference(conf->mirrors[i].rdev)) != NULL &&
+                   !test_bit(Faulty, &rdev->flags)) {
                        atomic_inc(&rdev->nr_pending);
-                       if (rdev->faulty) {
-                               atomic_dec(&rdev->nr_pending);
+                       if (test_bit(Faulty, &rdev->flags)) {
+                               rdev_dec_pending(rdev, mddev);
                                r1_bio->bios[i] = NULL;
                        } else
                                r1_bio->bios[i] = bio;
@@ -759,6 +857,10 @@ static int make_request(request_queue_t *q, struct bio * bio)
        atomic_set(&r1_bio->remaining, 0);
        atomic_set(&r1_bio->behind_remaining, 0);
 
+       do_barriers = bio->bi_rw & BIO_RW_BARRIER;
+       if (do_barriers)
+               set_bit(R1BIO_Barrier, &r1_bio->state);
+
        bio_list_init(&bl);
        for (i = 0; i < disks; i++) {
                struct bio *mbio;
@@ -771,7 +873,7 @@ static int make_request(request_queue_t *q, 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;
+               mbio->bi_rw = WRITE | do_barriers;
                mbio->bi_private = r1_bio;
 
                if (behind_pages) {
@@ -824,7 +926,7 @@ static void status(struct seq_file *seq, mddev_t *mddev)
        for (i = 0; i < conf->raid_disks; i++)
                seq_printf(seq, "%s",
                              conf->mirrors[i].rdev &&
-                             conf->mirrors[i].rdev->in_sync ? "U" : "_");
+                             test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
        seq_printf(seq, "]");
 }
 
@@ -840,14 +942,14 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
         * next level up know.
         * else mark the drive as failed
         */
-       if (rdev->in_sync
+       if (test_bit(In_sync, &rdev->flags)
            && conf->working_disks == 1)
                /*
                 * Don't fail the drive, act as though we were just a
                 * normal single drive
                 */
                return;
-       if (rdev->in_sync) {
+       if (test_bit(In_sync, &rdev->flags)) {
                mddev->degraded++;
                conf->working_disks--;
                /*
@@ -855,8 +957,8 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
                 */
                set_bit(MD_RECOVERY_ERR, &mddev->recovery);
        }
-       rdev->in_sync = 0;
-       rdev->faulty = 1;
+       clear_bit(In_sync, &rdev->flags);
+       set_bit(Faulty, &rdev->flags);
        mddev->sb_dirty = 1;
        printk(KERN_ALERT "raid1: Disk failure on %s, disabling device. \n"
                "       Operation continuing on %d devices\n",
@@ -881,20 +983,15 @@ static void print_conf(conf_t *conf)
                tmp = conf->mirrors + i;
                if (tmp->rdev)
                        printk(" disk %d, wo:%d, o:%d, dev:%s\n",
-                               i, !tmp->rdev->in_sync, !tmp->rdev->faulty,
+                               i, !test_bit(In_sync, &tmp->rdev->flags), !test_bit(Faulty, &tmp->rdev->flags),
                                bdevname(tmp->rdev->bdev,b));
        }
 }
 
 static void close_sync(conf_t *conf)
 {
-       spin_lock_irq(&conf->resync_lock);
-       wait_event_lock_irq(conf->wait_resume, !conf->barrier,
-                           conf->resync_lock,  raid1_unplug(conf->mddev->queue));
-       spin_unlock_irq(&conf->resync_lock);
-
-       if (conf->barrier) BUG();
-       if (waitqueue_active(&conf->wait_idle)) BUG();
+       wait_barrier(conf);
+       allow_barrier(conf);
 
        mempool_destroy(conf->r1buf_pool);
        conf->r1buf_pool = NULL;
@@ -913,11 +1010,11 @@ static int raid1_spare_active(mddev_t *mddev)
        for (i = 0; i < conf->raid_disks; i++) {
                tmp = conf->mirrors + i;
                if (tmp->rdev 
-                   && !tmp->rdev->faulty
-                   && !tmp->rdev->in_sync) {
+                   && !test_bit(Faulty, &tmp->rdev->flags)
+                   && !test_bit(In_sync, &tmp->rdev->flags)) {
                        conf->working_disks++;
                        mddev->degraded--;
-                       tmp->rdev->in_sync = 1;
+                       set_bit(In_sync, &tmp->rdev->flags);
                }
        }
 
@@ -933,9 +1030,6 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
        int mirror = 0;
        mirror_info_t *p;
 
-       if (rdev->saved_raid_disk >= 0 &&
-           conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
-               mirror = rdev->saved_raid_disk;
        for (mirror=0; mirror < mddev->raid_disks; mirror++)
                if ( !(p=conf->mirrors+mirror)->rdev) {
 
@@ -952,9 +1046,12 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                        p->head_position = 0;
                        rdev->raid_disk = mirror;
                        found = 1;
-                       if (rdev->saved_raid_disk != mirror)
+                       /* As all devices are equivalent, we don't need a full recovery
+                        * if this was recently any drive of the array
+                        */
+                       if (rdev->saved_raid_disk < 0)
                                conf->fullsync = 1;
-                       p->rdev = rdev;
+                       rcu_assign_pointer(p->rdev, rdev);
                        break;
                }
 
@@ -972,7 +1069,7 @@ static int raid1_remove_disk(mddev_t *mddev, int number)
        print_conf(conf);
        rdev = p->rdev;
        if (rdev) {
-               if (rdev->in_sync ||
+               if (test_bit(In_sync, &rdev->flags) ||
                    atomic_read(&rdev->nr_pending)) {
                        err = -EBUSY;
                        goto abort;
@@ -994,28 +1091,27 @@ abort:
 
 static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
 {
-       int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
        r1bio_t * r1_bio = (r1bio_t *)(bio->bi_private);
-       conf_t *conf = mddev_to_conf(r1_bio->mddev);
+       int i;
 
        if (bio->bi_size)
                return 1;
 
-       if (r1_bio->bios[r1_bio->read_disk] != bio)
-               BUG();
-       update_head_pos(r1_bio->read_disk, r1_bio);
+       for (i=r1_bio->mddev->raid_disks; i--; )
+               if (r1_bio->bios[i] == bio)
+                       break;
+       BUG_ON(i < 0);
+       update_head_pos(i, r1_bio);
        /*
         * we have read a block, now it needs to be re-written,
         * or re-read if the read failed.
         * We don't do much here, just schedule handling by raid1d
         */
-       if (!uptodate) {
-               md_error(r1_bio->mddev,
-                        conf->mirrors[r1_bio->read_disk].rdev);
-       } else
+       if (test_bit(BIO_UPTODATE, &bio->bi_flags))
                set_bit(R1BIO_Uptodate, &r1_bio->state);
-       rdev_dec_pending(conf->mirrors[r1_bio->read_disk].rdev, conf->mddev);
-       reschedule_retry(r1_bio);
+
+       if (atomic_dec_and_test(&r1_bio->remaining))
+               reschedule_retry(r1_bio);
        return 0;
 }
 
@@ -1045,7 +1141,6 @@ static int end_sync_write(struct bio *bio, unsigned int bytes_done, int error)
                md_done_sync(mddev, r1_bio->sectors, uptodate);
                put_buf(r1_bio);
        }
-       rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);
        return 0;
 }
 
@@ -1058,34 +1153,173 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
 
        bio = r1_bio->bios[r1_bio->read_disk];
 
-/*
-       if (r1_bio->sector == 0) printk("First sync write startss\n");
-*/
-       /*
-        * schedule writes
-        */
+
+       if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+               /* We have read all readable devices.  If we haven't
+                * got the block, then there is no hope left.
+                * If we have, then we want to do a comparison
+                * and skip the write if everything is the same.
+                * If any blocks failed to read, then we need to
+                * attempt an over-write
+                */
+               int primary;
+               if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
+                       for (i=0; i<mddev->raid_disks; i++)
+                               if (r1_bio->bios[i]->bi_end_io == end_sync_read)
+                                       md_error(mddev, conf->mirrors[i].rdev);
+
+                       md_done_sync(mddev, r1_bio->sectors, 1);
+                       put_buf(r1_bio);
+                       return;
+               }
+               for (primary=0; primary<mddev->raid_disks; primary++)
+                       if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
+                           test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
+                               r1_bio->bios[primary]->bi_end_io = NULL;
+                               rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
+                               break;
+                       }
+               r1_bio->read_disk = primary;
+               for (i=0; i<mddev->raid_disks; i++)
+                       if (r1_bio->bios[i]->bi_end_io == end_sync_read &&
+                           test_bit(BIO_UPTODATE, &r1_bio->bios[i]->bi_flags)) {
+                               int j;
+                               int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
+                               struct bio *pbio = r1_bio->bios[primary];
+                               struct bio *sbio = r1_bio->bios[i];
+                               for (j = vcnt; j-- ; )
+                                       if (memcmp(page_address(pbio->bi_io_vec[j].bv_page),
+                                                  page_address(sbio->bi_io_vec[j].bv_page),
+                                                  PAGE_SIZE))
+                                               break;
+                               if (j >= 0)
+                                       mddev->resync_mismatches += r1_bio->sectors;
+                               if (j < 0 || test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
+                                       sbio->bi_end_io = NULL;
+                                       rdev_dec_pending(conf->mirrors[i].rdev, mddev);
+                               } else {
+                                       /* fixup the bio for reuse */
+                                       sbio->bi_vcnt = vcnt;
+                                       sbio->bi_size = r1_bio->sectors << 9;
+                                       sbio->bi_idx = 0;
+                                       sbio->bi_phys_segments = 0;
+                                       sbio->bi_hw_segments = 0;
+                                       sbio->bi_hw_front_size = 0;
+                                       sbio->bi_hw_back_size = 0;
+                                       sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
+                                       sbio->bi_flags |= 1 << BIO_UPTODATE;
+                                       sbio->bi_next = NULL;
+                                       sbio->bi_sector = r1_bio->sector +
+                                               conf->mirrors[i].rdev->data_offset;
+                                       sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
+                               }
+                       }
+       }
        if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
-               /*
-                * There is no point trying a read-for-reconstruct as
-                * reconstruct is about to be aborted
+               /* ouch - failed to read all of that.
+                * Try some synchronous reads of other devices to get
+                * good data, much like with normal read errors.  Only
+                * read into the pages we already have so they we don't
+                * need to re-issue the read request.
+                * We don't need to freeze the array, because being in an
+                * active sync request, there is no normal IO, and
+                * no overlapping syncs.
                 */
-               char b[BDEVNAME_SIZE];
-               printk(KERN_ALERT "raid1: %s: unrecoverable I/O read error"
-                       " for block %llu\n",
-                       bdevname(bio->bi_bdev,b), 
-                       (unsigned long long)r1_bio->sector);
-               md_done_sync(mddev, r1_bio->sectors, 0);
-               put_buf(r1_bio);
-               return;
+               sector_t sect = r1_bio->sector;
+               int sectors = r1_bio->sectors;
+               int idx = 0;
+
+               while(sectors) {
+                       int s = sectors;
+                       int d = r1_bio->read_disk;
+                       int success = 0;
+                       mdk_rdev_t *rdev;
+
+                       if (s > (PAGE_SIZE>>9))
+                               s = PAGE_SIZE >> 9;
+                       do {
+                               if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
+                                       rdev = conf->mirrors[d].rdev;
+                                       if (sync_page_io(rdev->bdev,
+                                                        sect + rdev->data_offset,
+                                                        s<<9,
+                                                        bio->bi_io_vec[idx].bv_page,
+                                                        READ)) {
+                                               success = 1;
+                                               break;
+                                       }
+                               }
+                               d++;
+                               if (d == conf->raid_disks)
+                                       d = 0;
+                       } while (!success && d != r1_bio->read_disk);
+
+                       if (success) {
+                               int start = d;
+                               /* write it back and re-read */
+                               set_bit(R1BIO_Uptodate, &r1_bio->state);
+                               while (d != r1_bio->read_disk) {
+                                       if (d == 0)
+                                               d = conf->raid_disks;
+                                       d--;
+                                       if (r1_bio->bios[d]->bi_end_io != end_sync_read)
+                                               continue;
+                                       rdev = conf->mirrors[d].rdev;
+                                       atomic_add(s, &rdev->corrected_errors);
+                                       if (sync_page_io(rdev->bdev,
+                                                        sect + rdev->data_offset,
+                                                        s<<9,
+                                                        bio->bi_io_vec[idx].bv_page,
+                                                        WRITE) == 0)
+                                               md_error(mddev, rdev);
+                               }
+                               d = start;
+                               while (d != r1_bio->read_disk) {
+                                       if (d == 0)
+                                               d = conf->raid_disks;
+                                       d--;
+                                       if (r1_bio->bios[d]->bi_end_io != end_sync_read)
+                                               continue;
+                                       rdev = conf->mirrors[d].rdev;
+                                       if (sync_page_io(rdev->bdev,
+                                                        sect + rdev->data_offset,
+                                                        s<<9,
+                                                        bio->bi_io_vec[idx].bv_page,
+                                                        READ) == 0)
+                                               md_error(mddev, rdev);
+                               }
+                       } else {
+                               char b[BDEVNAME_SIZE];
+                               /* Cannot read from anywhere, array is toast */
+                               md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
+                               printk(KERN_ALERT "raid1: %s: unrecoverable I/O read error"
+                                      " for block %llu\n",
+                                      bdevname(bio->bi_bdev,b),
+                                      (unsigned long long)r1_bio->sector);
+                               md_done_sync(mddev, r1_bio->sectors, 0);
+                               put_buf(r1_bio);
+                               return;
+                       }
+                       sectors -= s;
+                       sect += s;
+                       idx ++;
+               }
        }
 
+       /*
+        * schedule writes
+        */
        atomic_set(&r1_bio->remaining, 1);
        for (i = 0; i < disks ; i++) {
                wbio = r1_bio->bios[i];
-               if (wbio->bi_end_io != end_sync_write)
+               if (wbio->bi_end_io == NULL ||
+                   (wbio->bi_end_io == end_sync_read &&
+                    (i == r1_bio->read_disk ||
+                     !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
                        continue;
 
-               atomic_inc(&conf->mirrors[i].rdev->nr_pending);
+               wbio->bi_rw = WRITE;
+               wbio->bi_end_io = end_sync_write;
                atomic_inc(&r1_bio->remaining);
                md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
 
@@ -1146,6 +1380,7 @@ static void raid1d(mddev_t *mddev)
                        break;
                r1_bio = list_entry(head->prev, r1bio_t, retry_list);
                list_del(head->prev);
+               conf->nr_queued--;
                spin_unlock_irqrestore(&conf->device_lock, flags);
 
                mddev = r1_bio->mddev;
@@ -1153,8 +1388,118 @@ 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 BIO_RW_BARRIER
+                        * requests which failed with -ENOTSUPP.  Hohumm..
+                        * Better resubmit without the barrier.
+                        * We know which devices to resubmit for, because
+                        * all others have had their bios[] entry cleared.
+                        */
+                       int i;
+                       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]) {
+                                       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;
+                                       bio->bi_private = r1_bio;
+                                       r1_bio->bios[i] = bio;
+                                       generic_make_request(bio);
+                               }
                } else {
                        int disk;
+
+                       /* we got a read error. Maybe the drive is bad.  Maybe just
+                        * the block and we can fix it.
+                        * We freeze all other IO, and try reading the block from
+                        * other devices.  When we find one, we re-write
+                        * and check it that fixes the read error.
+                        * This is all done synchronously while the array is
+                        * frozen
+                        */
+                       sector_t sect = r1_bio->sector;
+                       int sectors = r1_bio->sectors;
+                       freeze_array(conf);
+                       if (mddev->ro == 0) while(sectors) {
+                               int s = sectors;
+                               int d = r1_bio->read_disk;
+                               int success = 0;
+
+                               if (s > (PAGE_SIZE>>9))
+                                       s = PAGE_SIZE >> 9;
+
+                               do {
+                                       rdev = conf->mirrors[d].rdev;
+                                       if (rdev &&
+                                           test_bit(In_sync, &rdev->flags) &&
+                                           sync_page_io(rdev->bdev,
+                                                        sect + rdev->data_offset,
+                                                        s<<9,
+                                                        conf->tmppage, READ))
+                                               success = 1;
+                                       else {
+                                               d++;
+                                               if (d == conf->raid_disks)
+                                                       d = 0;
+                                       }
+                               } while (!success && d != r1_bio->read_disk);
+
+                               if (success) {
+                                       /* write it back and re-read */
+                                       int start = d;
+                                       while (d != r1_bio->read_disk) {
+                                               if (d==0)
+                                                       d = conf->raid_disks;
+                                               d--;
+                                               rdev = conf->mirrors[d].rdev;
+                                               atomic_add(s, &rdev->corrected_errors);
+                                               if (rdev &&
+                                                   test_bit(In_sync, &rdev->flags)) {
+                                                       if (sync_page_io(rdev->bdev,
+                                                                        sect + rdev->data_offset,
+                                                                        s<<9, conf->tmppage, WRITE) == 0)
+                                                               /* Well, this device is dead */
+                                                               md_error(mddev, rdev);
+                                               }
+                                       }
+                                       d = start;
+                                       while (d != r1_bio->read_disk) {
+                                               if (d==0)
+                                                       d = conf->raid_disks;
+                                               d--;
+                                               rdev = conf->mirrors[d].rdev;
+                                               if (rdev &&
+                                                   test_bit(In_sync, &rdev->flags)) {
+                                                       if (sync_page_io(rdev->bdev,
+                                                                        sect + rdev->data_offset,
+                                                                        s<<9, conf->tmppage, READ) == 0)
+                                                               /* Well, this device is dead */
+                                                               md_error(mddev, rdev);
+                                               }
+                                       }
+                               } else {
+                                       /* Cannot read from anywhere -- bye bye array */
+                                       md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
+                                       break;
+                               }
+                               sectors -= s;
+                               sect += s;
+                       }
+
+                       unfreeze_array(conf);
+
                        bio = r1_bio->bios[r1_bio->read_disk];
                        if ((disk=read_balance(conf, r1_bio)) == -1) {
                                printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
@@ -1163,7 +1508,8 @@ static void raid1d(mddev_t *mddev)
                                       (unsigned long long)r1_bio->sector);
                                raid_end_bio_io(r1_bio);
                        } else {
-                               r1_bio->bios[r1_bio->read_disk] = NULL;
+                               r1_bio->bios[r1_bio->read_disk] =
+                                       mddev->ro ? IO_BLOCKED : NULL;
                                r1_bio->read_disk = disk;
                                bio_put(bio);
                                bio = bio_clone(r1_bio->master_bio, GFP_NOIO);
@@ -1218,14 +1564,13 @@ static int init_resync(conf_t *conf)
 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
 {
        conf_t *conf = mddev_to_conf(mddev);
-       mirror_info_t *mirror;
        r1bio_t *r1_bio;
        struct bio *bio;
        sector_t max_sector, nr_sectors;
-       int disk;
+       int disk = -1;
        int i;
-       int wonly;
-       int write_targets = 0;
+       int wonly = -1;
+       int write_targets = 0, read_targets = 0;
        int sync_blocks;
        int still_degraded = 0;
 
@@ -1260,61 +1605,41 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
         * This call the bitmap_start_sync doesn't actually record anything
         */
        if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
-           !conf->fullsync) {
+           !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
                /* We can skip this block, and probably several more */
                *skipped = 1;
                return sync_blocks;
        }
        /*
-        * If there is non-resync activity waiting for us then
-        * put in a delay to throttle resync.
+        * If there is non-resync activity waiting for a turn,
+        * and resync is going fast enough,
+        * then let it though before starting on this new sync request.
         */
-       if (!go_faster && waitqueue_active(&conf->wait_resume))
+       if (!go_faster && conf->nr_waiting)
                msleep_interruptible(1000);
-       device_barrier(conf, sector_nr + RESYNC_SECTORS);
 
-       /*
-        * If reconstructing, and >1 working disc,
-        * could dedicate one to rebuild and others to
-        * service read requests ..
-        */
-       disk = conf->last_used;
-       /* make sure disk is operational */
-       wonly = disk;
-       while (conf->mirrors[disk].rdev == NULL ||
-              !conf->mirrors[disk].rdev->in_sync ||
-              test_bit(WriteMostly, &conf->mirrors[disk].rdev->flags)
-               ) {
-               if (conf->mirrors[disk].rdev  &&
-                   conf->mirrors[disk].rdev->in_sync)
-                       wonly = disk;
-               if (disk <= 0)
-                       disk = conf->raid_disks;
-               disk--;
-               if (disk == conf->last_used) {
-                       disk = wonly;
-                       break;
-               }
-       }
-       conf->last_used = disk;
-       atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
+       raise_barrier(conf);
 
-
-       mirror = conf->mirrors + disk;
+       conf->next_resync = sector_nr;
 
        r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
-
-       spin_lock_irq(&conf->resync_lock);
-       conf->nr_pending++;
-       spin_unlock_irq(&conf->resync_lock);
+       rcu_read_lock();
+       /*
+        * If we get a correctably read error during resync or recovery,
+        * we might want to read from a different device.  So we
+        * flag all drives that could conceivably be read from for READ,
+        * and any others (which will be non-In_sync devices) for WRITE.
+        * If a read fails, we try reading from something else for which READ
+        * is OK.
+        */
 
        r1_bio->mddev = mddev;
        r1_bio->sector = sector_nr;
        r1_bio->state = 0;
        set_bit(R1BIO_IsSync, &r1_bio->state);
-       r1_bio->read_disk = disk;
 
        for (i=0; i < conf->raid_disks; i++) {
+               mdk_rdev_t *rdev;
                bio = r1_bio->bios[i];
 
                /* take from bio_init */
@@ -1329,34 +1654,49 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                bio->bi_end_io = NULL;
                bio->bi_private = NULL;
 
-               if (i == disk) {
-                       bio->bi_rw = READ;
-                       bio->bi_end_io = end_sync_read;
-               } else if (conf->mirrors[i].rdev == NULL ||
-                          conf->mirrors[i].rdev->faulty) {
+               rdev = rcu_dereference(conf->mirrors[i].rdev);
+               if (rdev == NULL ||
+                          test_bit(Faulty, &rdev->flags)) {
                        still_degraded = 1;
                        continue;
-               } else if (!conf->mirrors[i].rdev->in_sync ||
-                          sector_nr + RESYNC_SECTORS > mddev->recovery_cp) {
+               } else if (!test_bit(In_sync, &rdev->flags)) {
                        bio->bi_rw = WRITE;
                        bio->bi_end_io = end_sync_write;
                        write_targets ++;
-               } else
-                       /* no need to read or write here */
-                       continue;
-               bio->bi_sector = sector_nr + conf->mirrors[i].rdev->data_offset;
-               bio->bi_bdev = conf->mirrors[i].rdev->bdev;
+               } else {
+                       /* may need to read from here */
+                       bio->bi_rw = READ;
+                       bio->bi_end_io = end_sync_read;
+                       if (test_bit(WriteMostly, &rdev->flags)) {
+                               if (wonly < 0)
+                                       wonly = i;
+                       } else {
+                               if (disk < 0)
+                                       disk = i;
+                       }
+                       read_targets++;
+               }
+               atomic_inc(&rdev->nr_pending);
+               bio->bi_sector = sector_nr + rdev->data_offset;
+               bio->bi_bdev = rdev->bdev;
                bio->bi_private = r1_bio;
        }
+       rcu_read_unlock();
+       if (disk < 0)
+               disk = wonly;
+       r1_bio->read_disk = disk;
+
+       if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
+               /* extra read targets are also write targets */
+               write_targets += read_targets-1;
 
-       if (write_targets == 0) {
+       if (write_targets == 0 || read_targets == 0) {
                /* There is nowhere to write, so all non-sync
                 * drives must be failed - so we are finished
                 */
                sector_t rv = max_sector - sector_nr;
                *skipped = 1;
                put_buf(r1_bio);
-               rdev_dec_pending(conf->mirrors[disk].rdev, mddev);
                return rv;
        }
 
@@ -1371,8 +1711,9 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                        break;
                if (sync_blocks == 0) {
                        if (!bitmap_start_sync(mddev->bitmap, sector_nr,
-                                       &sync_blocks, still_degraded) &&
-                                       !conf->fullsync)
+                                              &sync_blocks, still_degraded) &&
+                           !conf->fullsync &&
+                           !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
                                break;
                        if (sync_blocks < (PAGE_SIZE>>9))
                                BUG();
@@ -1383,10 +1724,10 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                for (i=0 ; i < conf->raid_disks; i++) {
                        bio = r1_bio->bios[i];
                        if (bio->bi_end_io) {
-                               page = r1_bio->bios[0]->bi_io_vec[bio->bi_vcnt].bv_page;
+                               page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
                                if (bio_add_page(bio, page, len, 0) == 0) {
                                        /* stop here */
-                                       r1_bio->bios[0]->bi_io_vec[bio->bi_vcnt].bv_page = page;
+                                       bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
                                        while (i > 0) {
                                                i--;
                                                bio = r1_bio->bios[i];
@@ -1406,12 +1747,28 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                sync_blocks -= (len>>9);
        } while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
  bio_full:
-       bio = r1_bio->bios[disk];
        r1_bio->sectors = nr_sectors;
 
-       md_sync_acct(mirror->rdev->bdev, nr_sectors);
+       /* For a user-requested sync, we read all readable devices and do a
+        * compare
+        */
+       if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+               atomic_set(&r1_bio->remaining, read_targets);
+               for (i=0; i<conf->raid_disks; i++) {
+                       bio = r1_bio->bios[i];
+                       if (bio->bi_end_io == end_sync_read) {
+                               md_sync_acct(conf->mirrors[i].rdev->bdev, nr_sectors);
+                               generic_make_request(bio);
+                       }
+               }
+       } else {
+               atomic_set(&r1_bio->remaining, 1);
+               bio = r1_bio->bios[r1_bio->read_disk];
+               md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev,
+                            nr_sectors);
+               generic_make_request(bio);
 
-       generic_make_request(bio);
+       }
 
        return nr_sectors;
 }
@@ -1434,18 +1791,19 @@ static int run(mddev_t *mddev)
         * bookkeeping area. [whatever we allocate in run(),
         * should be freed in stop()]
         */
-       conf = kmalloc(sizeof(conf_t), GFP_KERNEL);
+       conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
        mddev->private = conf;
        if (!conf)
                goto out_no_mem;
 
-       memset(conf, 0, sizeof(*conf));
-       conf->mirrors = kmalloc(sizeof(struct mirror_info)*mddev->raid_disks, 
+       conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
                                 GFP_KERNEL);
        if (!conf->mirrors)
                goto out_no_mem;
 
-       memset(conf->mirrors, 0, sizeof(struct mirror_info)*mddev->raid_disks);
+       conf->tmppage = alloc_page(GFP_KERNEL);
+       if (!conf->tmppage)
+               goto out_no_mem;
 
        conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
        if (!conf->poolinfo)
@@ -1478,7 +1836,7 @@ static int run(mddev_t *mddev)
                        blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 
                disk->head_position = 0;
-               if (!rdev->faulty && rdev->in_sync)
+               if (!test_bit(Faulty, &rdev->flags) && test_bit(In_sync, &rdev->flags))
                        conf->working_disks++;
        }
        conf->raid_disks = mddev->raid_disks;
@@ -1489,8 +1847,7 @@ static int run(mddev_t *mddev)
                mddev->recovery_cp = MaxSector;
 
        spin_lock_init(&conf->resync_lock);
-       init_waitqueue_head(&conf->wait_idle);
-       init_waitqueue_head(&conf->wait_resume);
+       init_waitqueue_head(&conf->wait_barrier);
 
        bio_list_init(&conf->pending_bio_list);
        bio_list_init(&conf->flushing_bio_list);
@@ -1518,7 +1875,7 @@ static int run(mddev_t *mddev)
         */
        for (j = 0; j < conf->raid_disks &&
                     (!conf->mirrors[j].rdev ||
-                     !conf->mirrors[j].rdev->in_sync) ; j++)
+                     !test_bit(In_sync, &conf->mirrors[j].rdev->flags)) ; j++)
                /* nothing */;
        conf->last_used = j;
 
@@ -1530,7 +1887,6 @@ static int run(mddev_t *mddev)
                       mdname(mddev));
                goto out_free_conf;
        }
-       if (mddev->bitmap) mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
 
        printk(KERN_INFO 
                "raid1: raid set %s active with %d out of %d mirrors\n",
@@ -1555,6 +1911,7 @@ out_free_conf:
                if (conf->r1bio_pool)
                        mempool_destroy(conf->r1bio_pool);
                kfree(conf->mirrors);
+               safe_put_page(conf->tmppage);
                kfree(conf->poolinfo);
                kfree(conf);
                mddev->private = NULL;
@@ -1653,19 +2010,14 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
                kfree(newpoolinfo);
                return -ENOMEM;
        }
-       newmirrors = kmalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
+       newmirrors = kzalloc(sizeof(struct mirror_info) * raid_disks, GFP_KERNEL);
        if (!newmirrors) {
                kfree(newpoolinfo);
                mempool_destroy(newpool);
                return -ENOMEM;
        }
-       memset(newmirrors, 0, sizeof(struct mirror_info)*raid_disks);
 
-       spin_lock_irq(&conf->resync_lock);
-       conf->barrier++;
-       wait_event_lock_irq(conf->wait_idle, !conf->nr_pending,
-                           conf->resync_lock, raid1_unplug(mddev->queue));
-       spin_unlock_irq(&conf->resync_lock);
+       raise_barrier(conf);
 
        /* ok, everything is stopped */
        oldpool = conf->r1bio_pool;
@@ -1685,12 +2037,7 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
        conf->raid_disks = mddev->raid_disks = raid_disks;
 
        conf->last_used = 0; /* just make sure it is in-range */
-       spin_lock_irq(&conf->resync_lock);
-       conf->barrier--;
-       spin_unlock_irq(&conf->resync_lock);
-       wake_up(&conf->wait_resume);
-       wake_up(&conf->wait_idle);
-
+       lower_barrier(conf);
 
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        md_wakeup_thread(mddev->thread);
@@ -1705,33 +2052,19 @@ static void raid1_quiesce(mddev_t *mddev, int state)
 
        switch(state) {
        case 1:
-               spin_lock_irq(&conf->resync_lock);
-               conf->barrier++;
-               wait_event_lock_irq(conf->wait_idle, !conf->nr_pending,
-                                   conf->resync_lock, raid1_unplug(mddev->queue));
-               spin_unlock_irq(&conf->resync_lock);
+               raise_barrier(conf);
                break;
        case 0:
-               spin_lock_irq(&conf->resync_lock);
-               conf->barrier--;
-               spin_unlock_irq(&conf->resync_lock);
-               wake_up(&conf->wait_resume);
-               wake_up(&conf->wait_idle);
+               lower_barrier(conf);
                break;
        }
-       if (mddev->thread) {
-               if (mddev->bitmap)
-                       mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
-               else
-                       mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
-               md_wakeup_thread(mddev->thread);
-       }
 }
 
 
-static mdk_personality_t raid1_personality =
+static struct mdk_personality raid1_personality =
 {
        .name           = "raid1",
+       .level          = 1,
        .owner          = THIS_MODULE,
        .make_request   = make_request,
        .run            = run,
@@ -1749,15 +2082,17 @@ static mdk_personality_t raid1_personality =
 
 static int __init raid_init(void)
 {
-       return register_md_personality(RAID1, &raid1_personality);
+       return register_md_personality(&raid1_personality);
 }
 
 static void raid_exit(void)
 {
-       unregister_md_personality(RAID1);
+       unregister_md_personality(&raid1_personality);
 }
 
 module_init(raid_init);
 module_exit(raid_exit);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("md-personality-3"); /* RAID1 */
+MODULE_ALIAS("md-raid1");
+MODULE_ALIAS("md-level-1");