md: Relax checks on ->max_disks when external metadata handling is used.

When metadata is being managed by user-space, md doesn't know
what the maximum number of devices allowed in an array is
so ->max_disks is 0.  In this case we should allow any (+ve)
number of disks.

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

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 766be8701281..46bdf4b38be8 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2801,8 +2801,9 @@ static void analyze_sbs(mddev_t * mddev)
 
         i = 0;
         rdev_for_each(rdev, tmp, mddev) {
-                if (rdev->desc_nr >= mddev->max_disks ||
-                    i > mddev->max_disks) {
+                if (mddev->max_disks &&
+                    (rdev->desc_nr >= mddev->max_disks ||
+                     i > mddev->max_disks)) {
                         printk(KERN_WARNING
                                "md: %s: %s: only %d devices permitted\n",
                                mdname(mddev), bdevname(rdev->bdev, b),
@@ -5406,7 +5407,7 @@ static int update_raid_disks(mddev_t *mddev, int raid_disks)
         if (mddev->pers->check_reshape == NULL)
                 return -EINVAL;
         if (raid_disks <= 0 ||
-            raid_disks >= mddev->max_disks)
+            (mddev->max_disks && raid_disks >= mddev->max_disks))
                 return -EINVAL;
         if (mddev->sync_thread || mddev->reshape_position != MaxSector)
                 return -EBUSY;