cifs: Check if server supports reparse points before using them

Do not attempt to query or create reparse point when server fs does not
support it. This will prevent creating unusable empty object on the server.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pali

fs/smb/client/cifssmb.c

@@ -2709,6 +2709,9 @@ int cifs_query_reparse_point(const unsigned int xid,
 	if (cap_unix(tcon->ses))
 		return -EOPNOTSUPP;
 
+	if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))
+		return -EOPNOTSUPP;
+
 	oparms = (struct cifs_open_parms) {
 		.tcon = tcon,
 		.cifs_sb = cifs_sb,

fs/smb/client/link.c

@@ -643,7 +643,8 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
 	case CIFS_SYMLINK_TYPE_NATIVE:
 	case CIFS_SYMLINK_TYPE_NFS:
 	case CIFS_SYMLINK_TYPE_WSL:
-		if (server->ops->create_reparse_symlink) {
+		if (server->ops->create_reparse_symlink &&
+		    (le32_to_cpu(pTcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS)) {
 			rc = server->ops->create_reparse_symlink(xid, inode,
 								 direntry,
 								 pTcon,

fs/smb/client/smb2inode.c

@@ -1273,6 +1273,14 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data,
 	int rc;
 	int i;
 
+	/*
+	 * If server filesystem does not support reparse points then do not
+	 * attempt to create reparse point. This will prevent creating unusable
+	 * empty object on the server.
+	 */
+	if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))
+		return ERR_PTR(-EOPNOTSUPP);
+
 	oparms = CIFS_OPARMS(cifs_sb, tcon, full_path,
 			     SYNCHRONIZE | DELETE |
 			     FILE_READ_ATTRIBUTES |

fs/smb/client/smb2ops.c

@@ -5229,7 +5229,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
 			  const char *full_path, umode_t mode, dev_t dev)
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-	int rc;
+	int rc = -EOPNOTSUPP;
 
 	/*
 	 * Check if mounted with mount parm 'sfu' mount parm.
@@ -5240,7 +5240,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
 		rc = cifs_sfu_make_node(xid, inode, dentry, tcon,
 					full_path, mode, dev);
-	} else {
+	} else if (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) {
 		rc = smb2_mknod_reparse(xid, inode, dentry, tcon,
 					full_path, mode, dev);
 	}