ksmbd: don't remove dos attribute xattr on O_TRUNC open

When smb client open file in ksmbd share with O_TRUNC, dos attribute
xattr is removed as well as data in file. This cause the FSCTL_SET_SPARSE
request from the client fails because ksmbd can't update the dos attribute
after setting ATTR_SPARSE_FILE. And this patch fix xfstests generic/469
test also.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb2pdu.c

@@ -2330,15 +2330,15 @@ static int smb2_remove_smb_xattrs(struct path *path)
 			name += strlen(name) + 1) {
 		ksmbd_debug(SMB, "%s, len %zd\n", name, strlen(name));
 
-		if (strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
-		    strncmp(&name[XATTR_USER_PREFIX_LEN], DOS_ATTRIBUTE_PREFIX,
-			    DOS_ATTRIBUTE_PREFIX_LEN) &&
-		    strncmp(&name[XATTR_USER_PREFIX_LEN], STREAM_PREFIX, STREAM_PREFIX_LEN))
-			continue;
-
-		err = ksmbd_vfs_remove_xattr(user_ns, path->dentry, name);
-		if (err)
-			ksmbd_debug(SMB, "remove xattr failed : %s\n", name);
+		if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
+		    !strncmp(&name[XATTR_USER_PREFIX_LEN], STREAM_PREFIX,
+			     STREAM_PREFIX_LEN)) {
+			err = ksmbd_vfs_remove_xattr(user_ns, path->dentry,
+						     name);
+			if (err)
+				ksmbd_debug(SMB, "remove xattr failed : %s\n",
+					    name);
+		}
 	}
 out:
 	kvfree(xattr_list);