ksmbd: Fix unsigned expression compared with zero

The return value of the ksmbd_vfs_getcasexattr() is signed.
However, the return value is being assigned to an unsigned
variable and subsequently recasted, causing warnings. Use
a signed type.
Signed-off-by: Wang Ming <machel@vivo.com>
Acked-by: Tom Talpey <tom@talpey.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/vfs.c

@@ -412,7 +412,8 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 {
 	char *stream_buf = NULL, *wbuf;
 	struct mnt_idmap *idmap = file_mnt_idmap(fp->filp);
-	size_t size, v_len;
+	size_t size;
+	ssize_t v_len;
 	int err = 0;
 
 	ksmbd_debug(VFS, "write stream data pos : %llu, count : %zd\n",
@@ -429,9 +430,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
 				       fp->stream.name,
 				       fp->stream.size,
 				       &stream_buf);
-	if ((int)v_len < 0) {
+	if (v_len < 0) {
 		pr_err("not found stream in xattr : %zd\n", v_len);
-		err = (int)v_len;
+		err = v_len;
 		goto out;
 	}