Btrfs: add fiemap's flag check

When the flag not supported is specified, it is necessary to return the error
to the caller.
So, we add the validity check of the fiemap's flag.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/inode.c

@@ -6595,9 +6595,17 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 		   btrfs_submit_direct, 0);
 }
 
+#define BTRFS_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC)
+
 static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len)
 {
+	int	ret;
+
+	ret = fiemap_check_flags(fieinfo, BTRFS_FIEMAP_FLAGS);
+	if (ret)
+		return ret;
+
 	return extent_fiemap(inode, fieinfo, start, len, btrfs_get_extent_fiemap);
 }