CIFS: check new file size when extending file by fallocate

xfstests generic/228 checks if fallocate respect RLIMIT_FSIZE.
After fallocate mode 0 extending enabled, we can hit this failure.
Fix this by check the new file size with vfs helper, return
error if file size is larger then RLIMIT_FSIZE(ulimit -f).

This patch has been tested by LTP/xfstests aginst samba and
Windows server.

Acked-by: Ronnie Sahlberg <[email protected]>
Signed-off-by: Murphy Zhou <[email protected]>
Signed-off-by: Steve French <[email protected]>
CC: Stable <[email protected]>

Author: Murphy Zhou

fs/cifs/smb2ops.c

@@ -3255,6 +3255,10 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
 	 * Extending the file
 	 */
 	if ((keep_size == false) && i_size_read(inode) < off + len) {
+		rc = inode_newsize_ok(inode, off + len);
+		if (rc)
+			goto out;
+
 		if ((cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE) == 0)
 			smb2_set_sparse(xid, tcon, cfile, inode, false);