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>

1 files changed, 56 insertions, 20 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f7fb2b87ad89..4fdc6d02b447 100644
--- 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 =
 {