1 files changed, 87 insertions, 37 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 1023c4e48a91..76eed592371e 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3725,6 +3725,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
         int i;
         int dd_idx;
         sector_t writepos, safepos, gap;
+        sector_t stripe_addr;
 
         if (sector_nr == 0) {
                 /* If restarting in the middle, skip the initial sectors */
@@ -3782,10 +3783,21 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
                 wake_up(&conf->wait_for_overlap);
         }
 
+        if (mddev->delta_disks < 0) {
+                BUG_ON(conf->reshape_progress == 0);
+                stripe_addr = writepos;
+                BUG_ON((mddev->dev_sectors &
+                        ~((sector_t)mddev->chunk_size / 512 - 1))
+                       - (conf->chunk_size / 512) - stripe_addr
+                       != sector_nr);
+        } else {
+                BUG_ON(writepos != sector_nr + conf->chunk_size / 512);
+                stripe_addr = sector_nr;
+        }
         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
                 int j;
                 int skipped = 0;
-                sh = get_active_stripe(conf, sector_nr+i, 0, 0);
+                sh = get_active_stripe(conf, stripe_addr+i, 0, 0);
                 set_bit(STRIPE_EXPANDING, &sh->state);
                 atomic_inc(&conf->reshape_stripes);
                 /* If any of this stripe is beyond the end of the old
@@ -3825,10 +3837,10 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
          * block on the destination stripes.
          */
         first_sector =
-                raid5_compute_sector(conf, sector_nr*(new_data_disks),
+                raid5_compute_sector(conf, stripe_addr*(new_data_disks),
                                      1, &dd_idx, NULL);
         last_sector =
-                raid5_compute_sector(conf, ((sector_nr+conf->chunk_size/512)
+                raid5_compute_sector(conf, ((stripe_addr+conf->chunk_size/512)
                                             *(new_data_disks) - 1),
                                      1, &dd_idx, NULL);
         if (last_sector >= mddev->dev_sectors)
@@ -4366,12 +4378,6 @@ static int run(mddev_t *mddev)
                                mdname(mddev));
                         return -EINVAL;
                 }
-                if (mddev->delta_disks <= 0) {
-                        printk(KERN_ERR "raid5: %s: unsupported reshape "
-                               "(reduce disks) required - aborting.\n",
-                               mdname(mddev));
-                        return -EINVAL;
-                }
                 old_disks = mddev->raid_disks - mddev->delta_disks;
                 /* reshape_position must be on a new-stripe boundary, and one
                  * further up in new geometry must map after here in old
@@ -4648,6 +4654,10 @@ static int raid5_remove_disk(mddev_t *mddev, int number)
         print_raid5_conf(conf);
         rdev = p->rdev;
         if (rdev) {
+                if (number >= conf->raid_disks &&
+                    conf->reshape_progress == MaxSector)
+                        clear_bit(In_sync, &rdev->flags);
+
                 if (test_bit(In_sync, &rdev->flags) ||
                     atomic_read(&rdev->nr_pending)) {
                         err = -EBUSY;
@@ -4657,7 +4667,8 @@ static int raid5_remove_disk(mddev_t *mddev, int number)
                  * isn't possible.
                  */
                 if (!test_bit(Faulty, &rdev->flags) &&
-                    mddev->degraded <= conf->max_degraded) {
+                    mddev->degraded <= conf->max_degraded &&
+                    number < conf->raid_disks) {
                         err = -EBUSY;
                         goto abort;
                 }
@@ -4745,16 +4756,26 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
 static int raid5_check_reshape(mddev_t *mddev)
 {
         raid5_conf_t *conf = mddev_to_conf(mddev);
-        int err;
 
-        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 */
         if (mddev->bitmap)
                 /* Cannot grow a bitmap yet */
                 return -EBUSY;
+        if (mddev->degraded > conf->max_degraded)
+                return -EINVAL;
+        if (mddev->delta_disks < 0) {
+                /* We might be able to shrink, but the devices must
+                 * be made bigger first.
+                 * For raid6, 4 is the minimum size.
+                 * Otherwise 2 is the minimum
+                 */
+                int min = 2;
+                if (mddev->level == 6)
+                        min = 4;
+                if (mddev->raid_disks + mddev->delta_disks < min)
+                        return -EINVAL;
+        }
 
         /* Can only proceed if there are plenty of stripe_heads.
          * We need a minimum of one full stripe,, and for sensible progress
@@ -4771,14 +4792,7 @@ static int raid5_check_reshape(mddev_t *mddev)
                 return -ENOSPC;
         }
 
-        err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
-        if (err)
-                return err;
-
-        if (mddev->degraded > conf->max_degraded)
-                return -EINVAL;
-        /* looks like we might be able to manage this */
-        return 0;
+        return resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
 }
 
 static int raid5_start_reshape(mddev_t *mddev)
@@ -4803,6 +4817,17 @@ static int raid5_start_reshape(mddev_t *mddev)
                  */
                 return -EINVAL;
 
+        /* Refuse to reduce size of the array.  Any reductions in
+         * array size must be through explicit setting of array_size
+         * attribute.
+         */
+        if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
+            < mddev->array_sectors) {
+                printk(KERN_ERR "md: %s: array size must be reduced "
+                       "before number of disks\n", mdname(mddev));
+                return -EINVAL;
+        }
+
         atomic_set(&conf->reshape_stripes, 0);
         spin_lock_irq(&conf->device_lock);
         conf->previous_raid_disks = conf->raid_disks;
@@ -4836,9 +4861,12 @@ static int raid5_start_reshape(mddev_t *mddev)
                                 break;
                 }
 
-        spin_lock_irqsave(&conf->device_lock, flags);
-        mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
-        spin_unlock_irqrestore(&conf->device_lock, flags);
+        if (mddev->delta_disks > 0) {
+                spin_lock_irqsave(&conf->device_lock, flags);
+                mddev->degraded = (conf->raid_disks - conf->previous_raid_disks)
+                        - added_devices;
+                spin_unlock_irqrestore(&conf->device_lock, flags);
+        }
         mddev->raid_disks = conf->raid_disks;
         mddev->reshape_position = 0;
         set_bit(MD_CHANGE_DEVS, &mddev->flags);
@@ -4863,6 +4891,9 @@ static int raid5_start_reshape(mddev_t *mddev)
 }
 #endif
 
+/* This is called from the reshape thread and should make any
+ * changes needed in 'conf'
+ */
 static void end_reshape(raid5_conf_t *conf)
 {
 
@@ -4886,25 +4917,44 @@ static void end_reshape(raid5_conf_t *conf)
         }
 }
 
+/* This is called from the raid5d thread with mddev_lock held.
+ * It makes config changes to the device.
+ */
 static void raid5_finish_reshape(mddev_t *mddev)
 {
         struct block_device *bdev;
 
         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 
-                md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
-                set_capacity(mddev->gendisk, mddev->array_sectors);
-                mddev->changed = 1;
-                mddev->reshape_position = MaxSector;
-
-                bdev = bdget_disk(mddev->gendisk, 0);
-                if (bdev) {
-                        mutex_lock(&bdev->bd_inode->i_mutex);
-                        i_size_write(bdev->bd_inode,
-                                     (loff_t)mddev->array_sectors << 9);
-                        mutex_unlock(&bdev->bd_inode->i_mutex);
-                        bdput(bdev);
+                if (mddev->delta_disks > 0) {
+                        md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
+                        set_capacity(mddev->gendisk, mddev->array_sectors);
+                        mddev->changed = 1;
+
+                        bdev = bdget_disk(mddev->gendisk, 0);
+                        if (bdev) {
+                                mutex_lock(&bdev->bd_inode->i_mutex);
+                                i_size_write(bdev->bd_inode,
+                                             (loff_t)mddev->array_sectors << 9);
+                                mutex_unlock(&bdev->bd_inode->i_mutex);
+                                bdput(bdev);
+                        }
+                } else {
+                        int d;
+                        raid5_conf_t *conf = mddev_to_conf(mddev);
+                        mddev->degraded = conf->raid_disks;
+                        for (d = 0; d < conf->raid_disks ; d++)
+                                if (conf->disks[d].rdev &&
+                                    test_bit(In_sync,
+                                             &conf->disks[d].rdev->flags))
+                                        mddev->degraded--;
+                        for (d = conf->raid_disks ;
+                             d < conf->raid_disks - mddev->delta_disks;
+                             d++)
+                                raid5_remove_disk(mddev, d);
                 }
+                mddev->reshape_position = MaxSector;
+                mddev->delta_disks = 0;
         }
 }