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, 5 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8d11cd1a0d8b..6eb95451f161 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4639,6 +4639,11 @@ static int update_size(mddev_t *mddev, sector_t num_sectors)
          */
         if (mddev->sync_thread)
                 return -EBUSY;
+        if (mddev->bitmap)
+                /* Sorry, cannot grow a bitmap yet, just remove it,
+                 * grow, and re-add.
+                 */
+                return -EBUSY;
         rdev_for_each(rdev, tmp, mddev) {
                 sector_t avail;
                 avail = rdev->size * 2;