md/raid5: allow layout and chunksize to be changed on active array.

If an array has 3 or more devices, we allow the chunksize or layout
to be changed and when a reshape starts, we use these as the 'new'
values.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f7fb2b87ad8919749d7f1196db87fde5abfe5c9f..4fdc6d02b4470dc6da819d4b9eb7cff694ee63fb 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4397,9 +4397,7 @@ static int run(mddev_t *mddev)
                int old_disks;
                int max_degraded = (mddev->level == 6 ? 2 : 1);
 
-               if (mddev->new_level != mddev->level ||
-                   mddev->new_layout != mddev->layout ||
-                   mddev->new_chunk != mddev->chunk_size) {
+               if (mddev->new_level != mddev->level) {
                        printk(KERN_ERR "raid5: %s: unsupported reshape "
                               "required - aborting.\n",
                               mdname(mddev));
@@ -4784,8 +4782,10 @@ static int raid5_check_reshape(mddev_t *mddev)
 {
        raid5_conf_t *conf = mddev_to_conf(mddev);
 
-       if (mddev->delta_disks == 0)
-               return 0; /* nothing to do */
+       if (mddev->delta_disks == 0 &&
+           mddev->new_layout == mddev->layout &&
+           mddev->new_chunk == mddev->chunk_size)
+               return -EINVAL; /* nothing to do */
        if (mddev->bitmap)
                /* Cannot grow a bitmap yet */
                return -EBUSY;
@@ -4860,6 +4860,10 @@ static int raid5_start_reshape(mddev_t *mddev)
        spin_lock_irq(&conf->device_lock);
        conf->previous_raid_disks = conf->raid_disks;
        conf->raid_disks += mddev->delta_disks;
+       conf->prev_chunk = conf->chunk_size;
+       conf->chunk_size = mddev->new_chunk;
+       conf->prev_algo = conf->algorithm;
+       conf->algorithm = mddev->new_layout;
        if (mddev->delta_disks < 0)
                conf->reshape_progress = raid5_size(mddev, 0, 0);
        else
@@ -4952,6 +4956,7 @@ static void end_reshape(raid5_conf_t *conf)
 static void raid5_finish_reshape(mddev_t *mddev)
 {
        struct block_device *bdev;
+       raid5_conf_t *conf = mddev_to_conf(mddev);
 
        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 
@@ -4970,7 +4975,6 @@ static void raid5_finish_reshape(mddev_t *mddev)
                        }
                } 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 &&
@@ -4982,6 +4986,8 @@ static void raid5_finish_reshape(mddev_t *mddev)
                             d++)
                                raid5_remove_disk(mddev, d);
                }
+               mddev->layout = conf->algorithm;
+               mddev->chunk_size = conf->chunk_size;
                mddev->reshape_position = MaxSector;
                mddev->delta_disks = 0;
        }
@@ -5080,11 +5086,10 @@ static void *raid5_takeover_raid6(mddev_t *mddev)
 
 static int raid5_reconfig(mddev_t *mddev, int new_layout, int new_chunk)
 {
-       /* Currently the layout and chunk size can only be changed
-        * for a 2-drive raid array, as in that case no data shuffling
-        * is required.
-        * Later we might validate these and set new_* so a reshape
-        * can complete the change.
+       /* For a 2-drive array, the layout and chunk size can be changed
+        * immediately as not restriping is needed.
+        * For larger arrays we record the new value - after validation
+        * to be used by a reshape pass.
         */
        raid5_conf_t *conf = mddev_to_conf(mddev);
 
@@ -5103,19 +5108,49 @@ static int raid5_reconfig(mddev_t *mddev, int new_layout, int new_chunk)
 
        /* They look valid */
 
-       if (mddev->raid_disks != 2)
-               return -EINVAL;
+       if (mddev->raid_disks == 2) {
 
-       if (new_layout >= 0) {
-               conf->algorithm = new_layout;
-               mddev->layout = mddev->new_layout = new_layout;
+               if (new_layout >= 0) {
+                       conf->algorithm = new_layout;
+                       mddev->layout = mddev->new_layout = new_layout;
+               }
+               if (new_chunk > 0) {
+                       conf->chunk_size = new_chunk;
+                       mddev->chunk_size = mddev->new_chunk = new_chunk;
+               }
+               set_bit(MD_CHANGE_DEVS, &mddev->flags);
+               md_wakeup_thread(mddev->thread);
+       } else {
+               if (new_layout >= 0)
+                       mddev->new_layout = new_layout;
+               if (new_chunk > 0)
+                       mddev->new_chunk = new_chunk;
        }
+       return 0;
+}
+
+static int raid6_reconfig(mddev_t *mddev, int new_layout, int new_chunk)
+{
+       if (new_layout >= 0 && !algorithm_valid_raid6(new_layout))
+               return -EINVAL;
        if (new_chunk > 0) {
-               conf->chunk_size = new_chunk;
-               mddev->chunk_size = mddev->new_chunk = new_chunk;
+               if (new_chunk & (new_chunk-1))
+                       /* not a power of 2 */
+                       return -EINVAL;
+               if (new_chunk < PAGE_SIZE)
+                       return -EINVAL;
+               if (mddev->array_sectors & ((new_chunk>>9)-1))
+                       /* not factor of array size */
+                       return -EINVAL;
        }
-       set_bit(MD_CHANGE_DEVS, &mddev->flags);
-       md_wakeup_thread(mddev->thread);
+
+       /* They look valid */
+
+       if (new_layout >= 0)
+               mddev->new_layout = new_layout;
+       if (new_chunk > 0)
+               mddev->new_chunk = new_chunk;
+
        return 0;
 }
 
@@ -5216,6 +5251,7 @@ static struct mdk_personality raid6_personality =
 #endif
        .quiesce        = raid5_quiesce,
        .takeover       = raid6_takeover,
+       .reconfig       = raid6_reconfig,
 };
 static struct mdk_personality raid5_personality =
 {