Fail safely when trying to grow an array with a write-intent bitmap.

We cannot currently change the size of a write-intent bitmap.
So if we change the size of an array which has such a bitmap, it
tries to set bits beyond the end of the bitmap.

For now, simply reject any request to change the size of an array
which has a bitmap.  mdadm can remove the bitmap and add a new one
after the array has changed size.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 40e939675657..17e0953c3c06 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4446,6 +4446,9 @@ static int raid5_check_reshape(mddev_t *mddev)
                 return -EINVAL; /* Cannot shrink array or change level yet */
         if (mddev->delta_disks == 0)
                 return 0; /* nothing to do */
+        if (mddev->bitmap)
+                /* Cannot grow a bitmap yet */
+                return -EBUSY;
 
         /* Can only proceed if there are plenty of stripe_heads.
          * We need a minimum of one full stripe,, and for sensible progress