From: NeilBrown Date: Tue, 31 Mar 2009 03:39:39 +0000 (+1100) Subject: md: add ->takeover method to support changing the personality managing an array X-Git-Tag: v2.6.30-rc1~241^2~26 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=245f46c2c221ef09c7db892f0e3fc2149be42052;p=~shefty%2Frdma-dev.git 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 --- diff --git a/drivers/md/md.c b/drivers/md/md.c index 6cb31f8da14..05b613b5e4b 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2649,18 +2649,101 @@ level_show(mddev_t *mddev, char *page) 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; } diff --git a/drivers/md/md.h b/drivers/md/md.h index 84b22d67ba1..8034f62a9d2 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -321,6 +321,16 @@ struct mdk_personality * others - reserved */ void (*quiesce) (mddev_t *mddev, int state); + /* takeover is used to transition an array from one + * personality to another. The new personality must be able + * to handle the data in the current layout. + * e.g. 2drive raid1 -> 2drive raid5 + * ndrive raid5 -> degraded n+1drive raid6 with special layout + * If the takeover succeeds, a new 'private' structure is returned. + * This needs to be installed and then ->run used to activate the + * array. + */ + void *(*takeover) (mddev_t *mddev); }; diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 81789fa7a02..5b346b41e51 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -933,8 +933,10 @@ static int grow_stripes(raid5_conf_t *conf, int num) struct kmem_cache *sc; int devs = conf->raid_disks; - sprintf(conf->cache_name[0], "raid5-%s", mdname(conf->mddev)); - sprintf(conf->cache_name[1], "raid5-%s-alt", mdname(conf->mddev)); + sprintf(conf->cache_name[0], + "raid%d-%s", conf->level, mdname(conf->mddev)); + sprintf(conf->cache_name[1], + "raid%d-%s-alt", conf->level, mdname(conf->mddev)); conf->active_name = 0; sc = kmem_cache_create(conf->cache_name[conf->active_name], sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev), @@ -4361,10 +4363,12 @@ static int run(mddev_t *mddev) BUG_ON(mddev->chunk_size != mddev->new_chunk); BUG_ON(mddev->delta_disks != 0); } - conf = setup_conf(mddev); - if (conf == NULL) - return -EIO; + if (mddev->private == NULL) + conf = setup_conf(mddev); + else + conf = mddev->private; + if (IS_ERR(conf)) return PTR_ERR(conf); @@ -4880,6 +4884,55 @@ static void raid5_quiesce(mddev_t *mddev, int state) } } +static struct mdk_personality raid5_personality; + +static void *raid6_takeover(mddev_t *mddev) +{ + /* Currently can only take over a raid5. We map the + * personality to an equivalent raid6 personality + * with the Q block at the end. + */ + int new_layout; + + if (mddev->pers != &raid5_personality) + return ERR_PTR(-EINVAL); + if (mddev->degraded > 1) + return ERR_PTR(-EINVAL); + if (mddev->raid_disks > 253) + return ERR_PTR(-EINVAL); + if (mddev->raid_disks < 3) + return ERR_PTR(-EINVAL); + + switch (mddev->layout) { + case ALGORITHM_LEFT_ASYMMETRIC: + new_layout = ALGORITHM_LEFT_ASYMMETRIC_6; + break; + case ALGORITHM_RIGHT_ASYMMETRIC: + new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6; + break; + case ALGORITHM_LEFT_SYMMETRIC: + new_layout = ALGORITHM_LEFT_SYMMETRIC_6; + break; + case ALGORITHM_RIGHT_SYMMETRIC: + new_layout = ALGORITHM_RIGHT_SYMMETRIC_6; + break; + case ALGORITHM_PARITY_0: + new_layout = ALGORITHM_PARITY_0_6; + break; + case ALGORITHM_PARITY_N: + new_layout = ALGORITHM_PARITY_N; + break; + default: + return ERR_PTR(-EINVAL); + } + mddev->new_level = 6; + mddev->new_layout = new_layout; + mddev->delta_disks = 1; + mddev->raid_disks += 1; + return setup_conf(mddev); +} + + static struct mdk_personality raid6_personality = { .name = "raid6", @@ -4900,6 +4953,7 @@ static struct mdk_personality raid6_personality = .start_reshape = raid5_start_reshape, #endif .quiesce = raid5_quiesce, + .takeover = raid6_takeover, }; static struct mdk_personality raid5_personality = {