md: Fix handling of raid5 array which is being reshaped to fewer devices.

When a raid5 (or raid6) array is being reshaped to have fewer devices,
conf->raid_disks is the latter and hence smaller number of devices.
However sometimes we want to use a number which is the total number of
currently required devices - the larger of the 'old' and 'new' sizes.
Before we implemented reducing the number of devices, this was always
'new' i.e. ->raid_disks.
Now we need max(raid_disks, previous_raid_disks) in those places.

This particularly affects assembling an array that was shutdown while
in the middle of a reshape to fewer devices.

md.c needs a similar fix when interpreting the md metadata.

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

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 26ba42a..10eb1fc 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2631,7 +2631,7 @@ static void analyze_sbs(mddev_t * mddev)
                        rdev->desc_nr = i++;
                        rdev->raid_disk = rdev->desc_nr;
                        set_bit(In_sync, &rdev->flags);
-               } else if (rdev->raid_disk >= mddev->raid_disks) {
+               } else if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks))) {
                        rdev->raid_disk = -1;
                        clear_bit(In_sync, &rdev->flags);
                }

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d4ce51b..c4366c9 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1238,22 +1238,22 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
 static int grow_one_stripe(raid5_conf_t *conf)
 {
        struct stripe_head *sh;
+       int disks = max(conf->raid_disks, conf->previous_raid_disks);
        sh = kmem_cache_alloc(conf->slab_cache, GFP_KERNEL);
        if (!sh)
                return 0;
-       memset(sh, 0, sizeof(*sh) + (conf->raid_disks-1)*sizeof(struct r5dev));
+       memset(sh, 0, sizeof(*sh) + (disks-1)*sizeof(struct r5dev));
        sh->raid_conf = conf;
        spin_lock_init(&sh->lock);
        #ifdef CONFIG_MULTICORE_RAID456
        init_waitqueue_head(&sh->ops.wait_for_ops);
        #endif
 
-       if (grow_buffers(sh, conf->raid_disks)) {
-               shrink_buffers(sh, conf->raid_disks);
+       if (grow_buffers(sh, disks)) {
+               shrink_buffers(sh, disks);
                kmem_cache_free(conf->slab_cache, sh);
                return 0;
        }
-       sh->disks = conf->raid_disks;
        /* we just created an active stripe so... */
        atomic_set(&sh->count, 1);
        atomic_inc(&conf->active_stripes);
@@ -1265,7 +1265,7 @@ static int grow_one_stripe(raid5_conf_t *conf)
 static int grow_stripes(raid5_conf_t *conf, int num)
 {
        struct kmem_cache *sc;
-       int devs = conf->raid_disks;
+       int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
        sprintf(conf->cache_name[0],
                "raid%d-%s", conf->level, mdname(conf->mddev));
@@ -3540,9 +3540,10 @@ static void unplug_slaves(mddev_t *mddev)
 {
        raid5_conf_t *conf = mddev->private;
        int i;
+       int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
        rcu_read_lock();
-       for (i = 0; i < conf->raid_disks; i++) {
+       for (i = 0; i < devs; i++) {
                mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
                if (rdev && !test_bit(Faulty, &rdev->flags) && atomic_read(&rdev->nr_pending)) {
                        struct request_queue *r_queue = bdev_get_queue(rdev->bdev);
@@ -4562,13 +4563,9 @@ raid5_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 
        if (!sectors)
                sectors = mddev->dev_sectors;
-       if (!raid_disks) {
+       if (!raid_disks)
                /* size is defined by the smallest of previous and new size */
-               if (conf->raid_disks < conf->previous_raid_disks)
-                       raid_disks = conf->raid_disks;
-               else
-                       raid_disks = conf->previous_raid_disks;
-       }
+               raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
 
        sectors &= ~((sector_t)mddev->chunk_sectors - 1);
        sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
@@ -4669,7 +4666,7 @@ static int raid5_alloc_percpu(raid5_conf_t *conf)
                        }
                        per_cpu_ptr(conf->percpu, cpu)->spare_page = spare_page;
                }
-               scribble = kmalloc(scribble_len(conf->raid_disks), GFP_KERNEL);
+               scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
                if (!scribble) {
                        err = -ENOMEM;
                        break;
@@ -4690,7 +4687,7 @@ static int raid5_alloc_percpu(raid5_conf_t *conf)
 static raid5_conf_t *setup_conf(mddev_t *mddev)
 {
        raid5_conf_t *conf;
-       int raid_disk, memory;
+       int raid_disk, memory, max_disks;
        mdk_rdev_t *rdev;
        struct disk_info *disk;
 
@@ -4740,13 +4737,14 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        conf->bypass_threshold = BYPASS_THRESHOLD;
 
        conf->raid_disks = mddev->raid_disks;
-       conf->scribble_len = scribble_len(conf->raid_disks);
        if (mddev->reshape_position == MaxSector)
                conf->previous_raid_disks = mddev->raid_disks;
        else
                conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
+       max_disks = max(conf->raid_disks, conf->previous_raid_disks);
+       conf->scribble_len = scribble_len(max_disks);
 
-       conf->disks = kzalloc(conf->raid_disks * sizeof(struct disk_info),
+       conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
                              GFP_KERNEL);
        if (!conf->disks)
                goto abort;
@@ -4764,7 +4762,7 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
 
        list_for_each_entry(rdev, &mddev->disks, same_set) {
                raid_disk = rdev->raid_disk;
-               if (raid_disk >= conf->raid_disks
+               if (raid_disk >= max_disks
                    || raid_disk < 0)
                        continue;
                disk = conf->disks + raid_disk;
@@ -4796,7 +4794,7 @@ static raid5_conf_t *setup_conf(mddev_t *mddev)
        }
 
        memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
-                conf->raid_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
+                max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
        if (grow_stripes(conf, conf->max_nr_stripes)) {
                printk(KERN_ERR
                        "raid5: couldn't allocate %dkB for buffers\n", memory);
@@ -4921,7 +4919,8 @@ static int run(mddev_t *mddev)
                    test_bit(In_sync, &rdev->flags))
                        working_disks++;
 
-       mddev->degraded = conf->raid_disks - working_disks;
+       mddev->degraded = (max(conf->raid_disks, conf->previous_raid_disks)
+                          - working_disks);
 
        if (mddev->degraded > conf->max_degraded) {
                printk(KERN_ERR "raid5: not enough operational devices for %s"