[PATCH] ext4: refuse ro to rw remount of fs with orphan inodes

In the rare case where we have skipped orphan inode processing due to a
readonly block device, and the block device subsequently changes back to
read-write, disallow a remount,rw transition of the filesystem when we have an
unprocessed orphan inodes as this would corrupt the list.

Ideally we should process the orphan inode list during the remount, but that's
trickier, and this plugs the hole for now.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>