[PATCH] common: Do not chown ro mountpoint when creating idmapped mount

[Gabriel Niebler <gniebler@suse.com>]

The function _idmapped_mount tries to change the ownership of the mountpoint
for which it aims to create an idmapped mount, to ensure that the mapped UID
and GID can actually create objects within it. Some tests set up a read-only
mount, however, which lets the chown call fail. This patch fixes the
function to check whether the mount is read-only and skip the chown, if so.

Signed-off-by: Gabriel Niebler <gniebler@suse.com>
---
 common/rc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/common/rc b/common/rc
index 81ce1026..19ab8062 100644
--- a/common/rc
+++ b/common/rc
@@ -414,8 +414,11 @@ _idmapped_mount()
 
 	# We create an idmapped mount where {g,u}id 0 writes to disk as
 	# {g,u}id 10000000 and $(id -u fsgqa) + 10000000. We change ownership
-        # of $mnt so {g,u} id 0 can actually create objects in there.
-	chown 10000000:10000000 $mnt || return 1
+	# of $mnt, provided it's not read-only, so {g,u} id 0 can actually
+	# create objects in there.
+	if [[ "$mount_rec" != *"ro,"* && "$mount_rec" != *",ro"* ]]; then
+		chown 10000000:10000000 $mnt || return 1
+	fi
 	$here/src/vfs/mount-idmapped \
 		--map-mount b:10000000:0:100000000000 \
 		$mnt $tmp
-- 
2.39.1