tmpfs: ZERO_RANGE and COLLAPSE_RANGE not currently supported

I was well aware of FALLOC_FL_ZERO_RANGE and FALLOC_FL_COLLAPSE_RANGE
support being added to fallocate(); but didn't realize until now that I
had been too stupid to future-proof shmem_fallocate() against new
additions.  -EOPNOTSUPP instead of going on to ordinary fallocation.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Cc: <stable@vger.kernel.org>	[3.15]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/shmem.c

@@ -1724,6 +1724,9 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 	pgoff_t start, index, end;
 	int error;
 
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
 	mutex_lock(&inode->i_mutex);
 
 	if (mode & FALLOC_FL_PUNCH_HOLE) {