Grow: block -n on external volumes.

Performing --raid-devices on external metadata volume should be blocked
as it causes unwanted behaviour.

Eg. Performing
mdadm -G /dev/md/volume -l10 -n4
on r0_d2 inside 4 disk container, returns
mdadm: Need 2 spares to avoid degraded array, only have 0.

Signed-off-by: Mateusz Kusiak <mateusz.kusiak@intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/Grow.c b/Grow.c
index 8a242b0f..f6efbc48 100644
--- a/Grow.c
+++ b/Grow.c
@@ -1892,6 +1892,14 @@ int Grow_reshape(char *devname, int fd,
 
 		if (retval) {
 			pr_err("Cannot read superblock for %s\n", devname);
+			close(cfd);
+			free(subarray);
+			return 1;
+		}
+
+		if (s->raiddisks && subarray) {
+			pr_err("--raid-devices operation can be performed on a container only\n");
+			close(cfd);
 			free(subarray);
 			return 1;
 		}