4 files changed, 58 insertions, 34 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index b9dfdfccdb78..1a637676a930 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2594,7 +2594,7 @@ static int do_md_run(mddev_t * mddev)
         strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
 
         if (mddev->reshape_position != MaxSector &&
-            pers->reshape == NULL) {
+            pers->start_reshape == NULL) {
                 /* This personality cannot handle reshaping... */
                 mddev->pers = NULL;
                 module_put(pers->owner);
@@ -3556,14 +3556,16 @@ static int update_raid_disks(mddev_t *mddev, int raid_disks)
 {
         int rv;
         /* change the number of raid disks */
-        if (mddev->pers->reshape == NULL)
+        if (mddev->pers->check_reshape == NULL)
                 return -EINVAL;
         if (raid_disks <= 0 ||
             raid_disks >= mddev->max_disks)
                 return -EINVAL;
-        if (mddev->sync_thread)
+        if (mddev->sync_thread || mddev->reshape_position != MaxSector)
                 return -EBUSY;
-        rv = mddev->pers->reshape(mddev, raid_disks);
+        mddev->delta_disks = raid_disks - mddev->raid_disks;
+
+        rv = mddev->pers->check_reshape(mddev);
         return rv;
 }
 
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b65b8cfbdf30..04418e10d1dc 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1976,7 +1976,7 @@ static int raid1_resize(mddev_t *mddev, sector_t sectors)
         return 0;
 }
 
-static int raid1_reshape(mddev_t *mddev, int raid_disks)
+static int raid1_reshape(mddev_t *mddev)
 {
         /* We need to:
          * 1/ resize the r1bio_pool
@@ -1993,10 +1993,22 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
         struct pool_info *newpoolinfo;
         mirror_info_t *newmirrors;
         conf_t *conf = mddev_to_conf(mddev);
-        int cnt;
+        int cnt, raid_disks;
 
         int d, d2;
 
+        /* Cannot change chunk_size, layout, or level */
+        if (mddev->chunk_size != mddev->new_chunk ||
+            mddev->layout != mddev->new_layout ||
+            mddev->level != mddev->new_level) {
+                mddev->new_chunk = mddev->chunk_size;
+                mddev->new_layout = mddev->layout;
+                mddev->new_level = mddev->level;
+                return -EINVAL;
+        }
+
+        raid_disks = mddev->raid_disks + mddev->delta_disks;
+
         if (raid_disks < conf->raid_disks) {
                 cnt=0;
                 for (d= 0; d < conf->raid_disks; d++)
@@ -2043,6 +2055,7 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
 
         mddev->degraded += (raid_disks - conf->raid_disks);
         conf->raid_disks = mddev->raid_disks = raid_disks;
+        mddev->delta_disks = 0;
 
         conf->last_used = 0; /* just make sure it is in-range */
         lower_barrier(conf);
@@ -2084,7 +2097,7 @@ static struct mdk_personality raid1_personality =
         .spare_active   = raid1_spare_active,
         .sync_request   = sync_request,
         .resize         = raid1_resize,
-        .reshape        = raid1_reshape,
+        .check_reshape  = raid1_reshape,
         .quiesce        = raid1_quiesce,
 };
 
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 089a32604305..355dafb98aac 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2590,21 +2590,15 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
 }
 
 #ifdef CONFIG_MD_RAID5_RESHAPE
-static int raid5_reshape(mddev_t *mddev, int raid_disks)
+static int raid5_check_reshape(mddev_t *mddev)
 {
         raid5_conf_t *conf = mddev_to_conf(mddev);
         int err;
-        mdk_rdev_t *rdev;
-        struct list_head *rtmp;
-        int spares = 0;
-        int added_devices = 0;
 
-        if (mddev->degraded ||
-            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
-                return -EBUSY;
-        if (conf->raid_disks > raid_disks)
-                return -EINVAL; /* Cannot shrink array yet */
-        if (conf->raid_disks == raid_disks)
+        if (mddev->delta_disks < 0 ||
+            mddev->new_level != mddev->level)
+                return -EINVAL; /* Cannot shrink array or change level yet */
+        if (mddev->delta_disks == 0)
                 return 0; /* nothing to do */
 
         /* Can only proceed if there are plenty of stripe_heads.
@@ -2615,30 +2609,48 @@ static int raid5_reshape(mddev_t *mddev, int raid_disks)
          * If the chunk size is greater, user-space should request more
          * stripe_heads first.
          */
-        if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
+        if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
+            (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
                 printk(KERN_WARNING "raid5: reshape: not enough stripes.  Needed %lu\n",
                        (mddev->chunk_size / STRIPE_SIZE)*4);
                 return -ENOSPC;
         }
 
+        err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
+        if (err)
+                return err;
+
+        /* looks like we might be able to manage this */
+        return 0;
+}
+
+static int raid5_start_reshape(mddev_t *mddev)
+{
+        raid5_conf_t *conf = mddev_to_conf(mddev);
+        mdk_rdev_t *rdev;
+        struct list_head *rtmp;
+        int spares = 0;
+        int added_devices = 0;
+
+        if (mddev->degraded ||
+            test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+                return -EBUSY;
+
         ITERATE_RDEV(mddev, rdev, rtmp)
                 if (rdev->raid_disk < 0 &&
                     !test_bit(Faulty, &rdev->flags))
                         spares++;
-        if (conf->raid_disks + spares < raid_disks-1)
+
+        if (spares < mddev->delta_disks-1)
                 /* Not enough devices even to make a degraded array
                  * of that size
                  */
                 return -EINVAL;
 
-        err = resize_stripes(conf, raid_disks);
-        if (err)
-                return err;
-
         atomic_set(&conf->reshape_stripes, 0);
         spin_lock_irq(&conf->device_lock);
         conf->previous_raid_disks = conf->raid_disks;
-        conf->raid_disks = raid_disks;
+        conf->raid_disks += mddev->delta_disks;
         conf->expand_progress = 0;
         conf->expand_lo = 0;
         spin_unlock_irq(&conf->device_lock);
@@ -2660,12 +2672,8 @@ static int raid5_reshape(mddev_t *mddev, int raid_disks)
                                 break;
                 }
 
-        mddev->degraded = (raid_disks - conf->previous_raid_disks) - added_devices;
-        mddev->new_chunk = mddev->chunk_size;
-        mddev->new_layout = mddev->layout;
-        mddev->new_level = mddev->level;
-        mddev->raid_disks = raid_disks;
-        mddev->delta_disks = raid_disks - conf->previous_raid_disks;
+        mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
+        mddev->raid_disks = conf->raid_disks;
         mddev->reshape_position = 0;
         mddev->sb_dirty = 1;
 
@@ -2679,7 +2687,6 @@ static int raid5_reshape(mddev_t *mddev, int raid_disks)
                 mddev->recovery = 0;
                 spin_lock_irq(&conf->device_lock);
                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
-                mddev->delta_disks = 0;
                 conf->expand_progress = MaxSector;
                 spin_unlock_irq(&conf->device_lock);
                 return -EAGAIN;
@@ -2752,7 +2759,8 @@ static struct mdk_personality raid5_personality =
         .sync_request   = sync_request,
         .resize         = raid5_resize,
 #ifdef CONFIG_MD_RAID5_RESHAPE
-        .reshape        = raid5_reshape,
+        .check_reshape  = raid5_check_reshape,
+        .start_reshape  = raid5_start_reshape,
 #endif
         .quiesce        = raid5_quiesce,
 };
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 1a6f9f2f6282..002ee631fabb 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -261,7 +261,8 @@ struct mdk_personality
         int (*spare_active) (mddev_t *mddev);
         sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
         int (*resize) (mddev_t *mddev, sector_t sectors);
-        int (*reshape) (mddev_t *mddev, int raid_disks);
+        int (*check_reshape) (mddev_t *mddev);
+        int (*start_reshape) (mddev_t *mddev);
         int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);
         /* quiesce moves between quiescence states
          * 0 - fully active