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>
This commit is contained in:
NeilBrown
parent
409c57f380
commit
245f46c2c2
101
drivers/md/md.c
101
drivers/md/md.c
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@ -2649,18 +2649,101 @@ level_show(mddev_t *mddev, char *page)
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static ssize_t
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level_store(mddev_t *mddev, const char *buf, size_t len)
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{
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char level[16];
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ssize_t rv = len;
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if (mddev->pers)
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struct mdk_personality *pers;
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void *priv;
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if (mddev->pers == NULL) {
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if (len == 0)
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return 0;
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if (len >= sizeof(mddev->clevel))
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return -ENOSPC;
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strncpy(mddev->clevel, buf, len);
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if (mddev->clevel[len-1] == '\n')
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len--;
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mddev->clevel[len] = 0;
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mddev->level = LEVEL_NONE;
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return rv;
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}
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/* request to change the personality. Need to ensure:
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* - array is not engaged in resync/recovery/reshape
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* - old personality can be suspended
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* - new personality will access other array.
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*/
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if (mddev->sync_thread || mddev->reshape_position != MaxSector)
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return -EBUSY;
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if (len == 0)
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return 0;
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if (len >= sizeof(mddev->clevel))
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return -ENOSPC;
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strncpy(mddev->clevel, buf, len);
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if (mddev->clevel[len-1] == '\n')
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if (!mddev->pers->quiesce) {
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printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
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mdname(mddev), mddev->pers->name);
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return -EINVAL;
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}
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/* Now find the new personality */
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if (len == 0 || len >= sizeof(level))
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return -EINVAL;
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strncpy(level, buf, len);
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if (level[len-1] == '\n')
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len--;
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mddev->clevel[len] = 0;
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mddev->level = LEVEL_NONE;
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level[len] = 0;
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request_module("md-%s", level);
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spin_lock(&pers_lock);
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pers = find_pers(LEVEL_NONE, level);
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if (!pers || !try_module_get(pers->owner)) {
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spin_unlock(&pers_lock);
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printk(KERN_WARNING "md: personality %s not loaded\n", level);
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return -EINVAL;
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}
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spin_unlock(&pers_lock);
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if (pers == mddev->pers) {
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/* Nothing to do! */
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module_put(pers->owner);
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return rv;
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}
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if (!pers->takeover) {
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module_put(pers->owner);
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printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
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mdname(mddev), level);
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return -EINVAL;
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}
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/* ->takeover must set new_* and/or delta_disks
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* if it succeeds, and may set them when it fails.
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*/
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priv = pers->takeover(mddev);
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if (IS_ERR(priv)) {
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mddev->new_level = mddev->level;
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mddev->new_layout = mddev->layout;
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mddev->new_chunk = mddev->chunk_size;
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mddev->raid_disks -= mddev->delta_disks;
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mddev->delta_disks = 0;
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module_put(pers->owner);
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printk(KERN_WARNING "md: %s: %s would not accept array\n",
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mdname(mddev), level);
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return PTR_ERR(priv);
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}
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/* Looks like we have a winner */
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mddev_suspend(mddev);
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mddev->pers->stop(mddev);
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module_put(mddev->pers->owner);
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mddev->pers = pers;
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mddev->private = priv;
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strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
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mddev->level = mddev->new_level;
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mddev->layout = mddev->new_layout;
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mddev->chunk_size = mddev->new_chunk;
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mddev->delta_disks = 0;
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pers->run(mddev);
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mddev_resume(mddev);
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set_bit(MD_CHANGE_DEVS, &mddev->flags);
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set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
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md_wakeup_thread(mddev->thread);
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return rv;
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}
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@ -321,6 +321,16 @@ struct mdk_personality
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* others - reserved
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*/
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void (*quiesce) (mddev_t *mddev, int state);
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/* takeover is used to transition an array from one
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* personality to another. The new personality must be able
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* to handle the data in the current layout.
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* e.g. 2drive raid1 -> 2drive raid5
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* ndrive raid5 -> degraded n+1drive raid6 with special layout
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* If the takeover succeeds, a new 'private' structure is returned.
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* This needs to be installed and then ->run used to activate the
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* array.
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*/
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void *(*takeover) (mddev_t *mddev);
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};
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@ -933,8 +933,10 @@ static int grow_stripes(raid5_conf_t *conf, int num)
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struct kmem_cache *sc;
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int devs = conf->raid_disks;
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sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev));
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sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev));
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sprintf(conf->cache_name[0],
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"raid%d-%s", conf->level, mdname(conf->mddev));
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sprintf(conf->cache_name[1],
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"raid%d-%s-alt", conf->level, mdname(conf->mddev));
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conf->active_name = 0;
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sc = kmem_cache_create(conf->cache_name[conf->active_name],
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sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
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@ -4361,10 +4363,12 @@ static int run(mddev_t *mddev)
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BUG_ON(mddev->chunk_size != mddev->new_chunk);
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BUG_ON(mddev->delta_disks != 0);
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}
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conf = setup_conf(mddev);
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if (conf == NULL)
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return -EIO;
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if (mddev->private == NULL)
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conf = setup_conf(mddev);
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else
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conf = mddev->private;
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if (IS_ERR(conf))
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return PTR_ERR(conf);
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@ -4880,6 +4884,55 @@ static void raid5_quiesce(mddev_t *mddev, int state)
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}
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}
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static struct mdk_personality raid5_personality;
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static void *raid6_takeover(mddev_t *mddev)
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{
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/* Currently can only take over a raid5. We map the
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* personality to an equivalent raid6 personality
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* with the Q block at the end.
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*/
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int new_layout;
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if (mddev->pers != &raid5_personality)
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return ERR_PTR(-EINVAL);
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if (mddev->degraded > 1)
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return ERR_PTR(-EINVAL);
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if (mddev->raid_disks > 253)
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return ERR_PTR(-EINVAL);
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if (mddev->raid_disks < 3)
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return ERR_PTR(-EINVAL);
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switch (mddev->layout) {
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case ALGORITHM_LEFT_ASYMMETRIC:
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new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
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break;
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case ALGORITHM_RIGHT_ASYMMETRIC:
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new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
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break;
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case ALGORITHM_LEFT_SYMMETRIC:
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new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
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break;
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case ALGORITHM_RIGHT_SYMMETRIC:
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new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
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break;
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case ALGORITHM_PARITY_0:
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new_layout = ALGORITHM_PARITY_0_6;
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break;
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case ALGORITHM_PARITY_N:
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new_layout = ALGORITHM_PARITY_N;
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break;
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default:
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return ERR_PTR(-EINVAL);
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}
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mddev->new_level = 6;
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mddev->new_layout = new_layout;
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mddev->delta_disks = 1;
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mddev->raid_disks += 1;
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return setup_conf(mddev);
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}
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static struct mdk_personality raid6_personality =
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{
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.name = "raid6",
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@ -4900,6 +4953,7 @@ static struct mdk_personality raid6_personality =
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.start_reshape = raid5_start_reshape,
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#endif
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.quiesce = raid5_quiesce,
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.takeover = raid6_takeover,
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};
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static struct mdk_personality raid5_personality =
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{
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