Commit 
4c63c2454ef incorrectly assumed that returning -ENOIOCTLCMD would
cause the native ioctl to be called.  The ->compat_ioctl callback is
expected to handle all ioctls, not just compat variants.  As a result,
when using 32-bit userspace on 64-bit kernels, everything except those
three ioctls would return -ENOTTY.
Fixes: 4c63c2454ef ("btrfs: bugfix: handle FS_IOC32_{GETFLAGS,SETFLAGS,GETVERSION} in btrfs_ioctl")
Cc: stable@vger.kernel.org
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
 #ifdef CONFIG_COMPAT
 long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
+       /*
+        * These all access 32-bit values anyway so no further
+        * handling is necessary.
+        */
        switch (cmd) {
        case FS_IOC32_GETFLAGS:
                cmd = FS_IOC_GETFLAGS;
        case FS_IOC32_GETVERSION:
                cmd = FS_IOC_GETVERSION;
                break;
-       default:
-               return -ENOIOCTLCMD;
        }
 
        return btrfs_ioctl(file, cmd, (unsigned long) compat_ptr(arg));