[PATCH] ext4: force ro mount if ext3_setup_super() fails

[Eric Sandeen <sandeen@redhat.com>]

If ext4_setup_super() fails i.e. due to a too-high revision,
the error is logged in dmesg but the fs is not mounted RO as
indicated.

Tested by:

# mkfs.ext4 -r 4 /dev/sdb6
# mount /dev/sdb6 /mnt/test
# dmesg | grep "too high"
[164919.759248] EXT4-fs (sdb6): revision level too high, forcing read-only mode
# grep sdb6 /proc/mounts
/dev/sdb6 /mnt/test2 ext4 rw,seclabel,relatime,data=ordered 0 0
                          ^^

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e1fb1d5..be67c0b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3592,7 +3592,8 @@ no_journal:
 		goto failed_mount4;
 	}
 
-	ext4_setup_super(sb, es, sb->s_flags & MS_RDONLY);
+	if (ext4_setup_super(sb, es, sb->s_flags & MS_RDONLY))
+		sb->s_flags |= MS_RDONLY;
 
 	/* determine the minimum size of new large inodes, if present */
 	if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {