md/raid1: add takeover support for raid5->raid1

A 2-device raid5 array can now be converted to raid1.

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

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 35b2d86..7549b0b 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -677,6 +677,7 @@ static void raise_barrier(conf_t *conf)
 static void lower_barrier(conf_t *conf)
 {
        unsigned long flags;
+       BUG_ON(conf->barrier <= 0);
        spin_lock_irqsave(&conf->resync_lock, flags);
        conf->barrier--;
        spin_unlock_irqrestore(&conf->resync_lock, flags);
@@ -1960,74 +1961,48 @@ static sector_t raid1_size(mddev_t *mddev, sector_t sectors, int raid_disks)
        return mddev->dev_sectors;
 }
 
-static int run(mddev_t *mddev)
+static conf_t *setup_conf(mddev_t *mddev)
 {
        conf_t *conf;
-       int i, j, disk_idx;
+       int i;
        mirror_info_t *disk;
        mdk_rdev_t *rdev;
+       int err = -ENOMEM;
 
-       if (mddev->level != 1) {
-               printk("raid1: %s: raid level not set to mirroring (%d)\n",
-                      mdname(mddev), mddev->level);
-               goto out;
-       }
-       if (mddev->reshape_position != MaxSector) {
-               printk("raid1: %s: reshape_position set but not supported\n",
-                      mdname(mddev));
-               goto out;
-       }
-       /*
-        * copy the already verified devices into our private RAID1
-        * bookkeeping area. [whatever we allocate in run(),
-        * should be freed in stop()]
-        */
        conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
-       mddev->private = conf;
        if (!conf)
-               goto out_no_mem;
+               goto abort;
 
        conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
                                 GFP_KERNEL);
        if (!conf->mirrors)
-               goto out_no_mem;
+               goto abort;
 
        conf->tmppage = alloc_page(GFP_KERNEL);
        if (!conf->tmppage)
-               goto out_no_mem;
+               goto abort;
 
-       conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
+       conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
        if (!conf->poolinfo)
-               goto out_no_mem;
-       conf->poolinfo->mddev = NULL;
+               goto abort;
        conf->poolinfo->raid_disks = mddev->raid_disks;
        conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
                                          r1bio_pool_free,
                                          conf->poolinfo);
        if (!conf->r1bio_pool)
-               goto out_no_mem;
+               goto abort;
+
        conf->poolinfo->mddev = mddev;
 
        spin_lock_init(&conf->device_lock);
-       mddev->queue->queue_lock = &conf->device_lock;
-
        list_for_each_entry(rdev, &mddev->disks, same_set) {
-               disk_idx = rdev->raid_disk;
+               int disk_idx = rdev->raid_disk;
                if (disk_idx >= mddev->raid_disks
                    || disk_idx < 0)
                        continue;
                disk = conf->mirrors + disk_idx;
 
                disk->rdev = rdev;
-               disk_stack_limits(mddev->gendisk, rdev->bdev,
-                                 rdev->data_offset << 9);
-               /* as we don't honour merge_bvec_fn, we must never risk
-                * violating it, so limit ->max_sector to one PAGE, as
-                * a one page request is never in violation.
-                */
-               if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
-                   queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
-                       blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
 
                disk->head_position = 0;
        }
@@ -2041,8 +2016,7 @@ static int run(mddev_t *mddev)
        bio_list_init(&conf->pending_bio_list);
        bio_list_init(&conf->flushing_bio_list);
 
-
-       mddev->degraded = 0;
+       conf->last_used = -1;
        for (i = 0; i < conf->raid_disks; i++) {
 
                disk = conf->mirrors + i;
@@ -2050,38 +2024,97 @@ static int run(mddev_t *mddev)
                if (!disk->rdev ||
                    !test_bit(In_sync, &disk->rdev->flags)) {
                        disk->head_position = 0;
-                       mddev->degraded++;
                        if (disk->rdev)
                                conf->fullsync = 1;
-               }
+               } else if (conf->last_used < 0)
+                       /*
+                        * The first working device is used as a
+                        * starting point to read balancing.
+                        */
+                       conf->last_used = i;
        }
-       if (mddev->degraded == conf->raid_disks) {
+
+       err = -EIO;
+       if (conf->last_used < 0) {
                printk(KERN_ERR "raid1: no operational mirrors for %s\n",
-                       mdname(mddev));
-               goto out_free_conf;
+                      mdname(mddev));
+               goto abort;
+       }
+       err = -ENOMEM;
+       conf->thread = md_register_thread(raid1d, mddev, NULL);
+       if (!conf->thread) {
+               printk(KERN_ERR
+                      "raid1: couldn't allocate thread for %s\n",
+                      mdname(mddev));
+               goto abort;
        }
-       if (conf->raid_disks - mddev->degraded == 1)
-               mddev->recovery_cp = MaxSector;
 
+       return conf;
+
+ abort:
+       if (conf) {
+               if (conf->r1bio_pool)
+                       mempool_destroy(conf->r1bio_pool);
+               kfree(conf->mirrors);
+               safe_put_page(conf->tmppage);
+               kfree(conf->poolinfo);
+               kfree(conf);
+       }
+       return ERR_PTR(err);
+}
+
+static int run(mddev_t *mddev)
+{
+       conf_t *conf;
+       int i;
+       mdk_rdev_t *rdev;
+
+       if (mddev->level != 1) {
+               printk("raid1: %s: raid level not set to mirroring (%d)\n",
+                      mdname(mddev), mddev->level);
+               return -EIO;
+       }
+       if (mddev->reshape_position != MaxSector) {
+               printk("raid1: %s: reshape_position set but not supported\n",
+                      mdname(mddev));
+               return -EIO;
+       }
        /*
-        * find the first working one and use it as a starting point
-        * to read balancing.
+        * copy the already verified devices into our private RAID1
+        * bookkeeping area. [whatever we allocate in run(),
+        * should be freed in stop()]
         */
-       for (j = 0; j < conf->raid_disks &&
-                    (!conf->mirrors[j].rdev ||
-                     !test_bit(In_sync, &conf->mirrors[j].rdev->flags)) ; j++)
-               /* nothing */;
-       conf->last_used = j;
+       if (mddev->private == NULL)
+               conf = setup_conf(mddev);
+       else
+               conf = mddev->private;
 
+       if (IS_ERR(conf))
+               return PTR_ERR(conf);
 
-       mddev->thread = md_register_thread(raid1d, mddev, NULL);
-       if (!mddev->thread) {
-               printk(KERN_ERR
-                      "raid1: couldn't allocate thread for %s\n",
-                      mdname(mddev));
-               goto out_free_conf;
+       mddev->queue->queue_lock = &conf->device_lock;
+       list_for_each_entry(rdev, &mddev->disks, same_set) {
+               disk_stack_limits(mddev->gendisk, rdev->bdev,
+                                 rdev->data_offset << 9);
+               /* as we don't honour merge_bvec_fn, we must never risk
+                * violating it, so limit ->max_sector to one PAGE, as
+                * a one page request is never in violation.
+                */
+               if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+                   queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9))
+                       blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);
        }
 
+       mddev->degraded = 0;
+       for (i=0; i < conf->raid_disks; i++)
+               if (conf->mirrors[i].rdev == NULL ||
+                   !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
+                   test_bit(Faulty, &conf->mirrors[i].rdev->flags))
+                       mddev->degraded++;
+
+       if (conf->raid_disks - mddev->degraded == 1)
+               mddev->recovery_cp = MaxSector;
+
        if (mddev->recovery_cp != MaxSector)
                printk(KERN_NOTICE "raid1: %s is not clean"
                       " -- starting background reconstruction\n",
@@ -2090,9 +2123,14 @@ static int run(mddev_t *mddev)
                "raid1: raid set %s active with %d out of %d mirrors\n",
                mdname(mddev), mddev->raid_disks - mddev->degraded, 
                mddev->raid_disks);
+
        /*
         * Ok, everything is just fine now
         */
+       mddev->thread = conf->thread;
+       conf->thread = NULL;
+       mddev->private = conf;
+
        md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
 
        mddev->queue->unplug_fn = raid1_unplug;
@@ -2100,23 +2138,6 @@ static int run(mddev_t *mddev)
        mddev->queue->backing_dev_info.congested_data = mddev;
        md_integrity_register(mddev);
        return 0;
-
-out_no_mem:
-       printk(KERN_ERR "raid1: couldn't allocate memory for %s\n",
-              mdname(mddev));
-
-out_free_conf:
-       if (conf) {
-               if (conf->r1bio_pool)
-                       mempool_destroy(conf->r1bio_pool);
-               kfree(conf->mirrors);
-               safe_put_page(conf->tmppage);
-               kfree(conf->poolinfo);
-               kfree(conf);
-               mddev->private = NULL;
-       }
-out:
-       return -EIO;
 }
 
 static int stop(mddev_t *mddev)
@@ -2302,6 +2323,23 @@ static void raid1_quiesce(mddev_t *mddev, int state)
        }
 }
 
+static void *raid1_takeover(mddev_t *mddev)
+{
+       /* raid1 can take over:
+        *  raid5 with 2 devices, any layout or chunk size
+        */
+       if (mddev->level == 5 && mddev->raid_disks == 2) {
+               conf_t *conf;
+               mddev->new_level = 1;
+               mddev->new_layout = 0;
+               mddev->new_chunk_sectors = 0;
+               conf = setup_conf(mddev);
+               if (!IS_ERR(conf))
+                       conf->barrier = 1;
+               return conf;
+       }
+       return ERR_PTR(-EINVAL);
+}
 
 static struct mdk_personality raid1_personality =
 {
@@ -2321,6 +2359,7 @@ static struct mdk_personality raid1_personality =
        .size           = raid1_size,
        .check_reshape  = raid1_reshape,
        .quiesce        = raid1_quiesce,
+       .takeover       = raid1_takeover,
 };
 
 static int __init raid_init(void)

diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index e87b84d..5f2d443 100644 (file)
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -59,6 +59,11 @@ struct r1_private_data_s {
 
        mempool_t *r1bio_pool;
        mempool_t *r1buf_pool;
+
+       /* When taking over an array from a different personality, we store
+        * the new thread here until we fully activate the array.
+        */
+       struct mdk_thread_s     *thread;
 };
 
 typedef struct r1_private_data_s conf_t;