md: add ->takeover method to support changing the personality managing an array
Implement this for RAID6 to be able to 'takeover' a RAID5 array. The
new RAID6 will use a layout which places Q on the last device, and
that device will be missing.
If there are any available spares, one will immediately have Q
recovered onto it.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6cb31f8..05b613b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2649,18 +2649,101 @@
static ssize_t
level_store(mddev_t *mddev, const char *buf, size_t len)
{
+ char level[16];
ssize_t rv = len;
- if (mddev->pers)
+ struct mdk_personality *pers;
+ void *priv;
+
+ if (mddev->pers == NULL) {
+ if (len == 0)
+ return 0;
+ if (len >= sizeof(mddev->clevel))
+ return -ENOSPC;
+ strncpy(mddev->clevel, buf, len);
+ if (mddev->clevel[len-1] == '\n')
+ len--;
+ mddev->clevel[len] = 0;
+ mddev->level = LEVEL_NONE;
+ return rv;
+ }
+
+ /* request to change the personality. Need to ensure:
+ * - array is not engaged in resync/recovery/reshape
+ * - old personality can be suspended
+ * - new personality will access other array.
+ */
+
+ if (mddev->sync_thread || mddev->reshape_position != MaxSector)
return -EBUSY;
- if (len == 0)
- return 0;
- if (len >= sizeof(mddev->clevel))
- return -ENOSPC;
- strncpy(mddev->clevel, buf, len);
- if (mddev->clevel[len-1] == '\n')
+
+ if (!mddev->pers->quiesce) {
+ printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
+ mdname(mddev), mddev->pers->name);
+ return -EINVAL;
+ }
+
+ /* Now find the new personality */
+ if (len == 0 || len >= sizeof(level))
+ return -EINVAL;
+ strncpy(level, buf, len);
+ if (level[len-1] == '\n')
len--;
- mddev->clevel[len] = 0;
- mddev->level = LEVEL_NONE;
+ level[len] = 0;
+
+ request_module("md-%s", level);
+ spin_lock(&pers_lock);
+ pers = find_pers(LEVEL_NONE, level);
+ if (!pers || !try_module_get(pers->owner)) {
+ spin_unlock(&pers_lock);
+ printk(KERN_WARNING "md: personality %s not loaded\n", level);
+ return -EINVAL;
+ }
+ spin_unlock(&pers_lock);
+
+ if (pers == mddev->pers) {
+ /* Nothing to do! */
+ module_put(pers->owner);
+ return rv;
+ }
+ if (!pers->takeover) {
+ module_put(pers->owner);
+ printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
+ mdname(mddev), level);
+ return -EINVAL;
+ }
+
+ /* ->takeover must set new_* and/or delta_disks
+ * if it succeeds, and may set them when it fails.
+ */
+ priv = pers->takeover(mddev);
+ if (IS_ERR(priv)) {
+ mddev->new_level = mddev->level;
+ mddev->new_layout = mddev->layout;
+ mddev->new_chunk = mddev->chunk_size;
+ mddev->raid_disks -= mddev->delta_disks;
+ mddev->delta_disks = 0;
+ module_put(pers->owner);
+ printk(KERN_WARNING "md: %s: %s would not accept array\n",
+ mdname(mddev), level);
+ return PTR_ERR(priv);
+ }
+
+ /* Looks like we have a winner */
+ mddev_suspend(mddev);
+ mddev->pers->stop(mddev);
+ module_put(mddev->pers->owner);
+ mddev->pers = pers;
+ mddev->private = priv;
+ strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
+ mddev->level = mddev->new_level;
+ mddev->layout = mddev->new_layout;
+ mddev->chunk_size = mddev->new_chunk;
+ mddev->delta_disks = 0;
+ pers->run(mddev);
+ mddev_resume(mddev);
+ set_bit(MD_CHANGE_DEVS, &mddev->flags);
+ set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+ md_wakeup_thread(mddev->thread);
return rv;
}