cifs: pass a path to open_shroot and check if it is the root or not

Move the check for the directory path into the open_shroot() function
but still fail for any non-root directories.
This is preparation for later when we will start using the cache also
for other directories than the root.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/smb2inode.c

@@ -524,8 +524,7 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 		return -ENOMEM;
 
 	/* If it is a root and its handle is cached then use it */
-	if (!strlen(full_path)) {
-		rc = open_shroot(xid, tcon, cifs_sb, &cfid);
+	rc = open_shroot(xid, tcon, full_path, cifs_sb, &cfid);
 	if (!rc) {
 		if (tcon->crfid.file_all_info_is_valid) {
 			move_smb2_info_to_cifs(data,
@@ -540,7 +539,6 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 		close_shroot(cfid);
 		goto out;
 	}
-	}
 
 	cifs_get_readable_path(tcon, full_path, &cfile);
 	rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,

fs/cifs/smb2ops.c

@@ -728,6 +728,7 @@ smb2_cached_lease_break(struct work_struct *work)
  * Open the directory at the root of a share
  */
 int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
+		const char *path,
 		struct cifs_sb_info *cifs_sb,
 		struct cached_fid **cfid)
 {
@@ -749,6 +750,9 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
 	if (tcon->nohandlecache)
 		return -ENOTSUPP;
 
+	if (strlen(path))
+		return -ENOTSUPP;
+
 	mutex_lock(&tcon->crfid.fid_mutex);
 	if (tcon->crfid.is_valid) {
 		cifs_dbg(FYI, "found a cached root file handle\n");
@@ -926,7 +930,7 @@ smb3_qfs_tcon(const unsigned int xid, struct cifs_tcon *tcon,
 	oparms.fid = &fid;
 	oparms.reconnect = false;
 
-	rc = open_shroot(xid, tcon, cifs_sb, &cfid);
+	rc = open_shroot(xid, tcon, "", cifs_sb, &cfid);
 	if (rc == 0)
 		memcpy(&fid, cfid->fid, sizeof(struct cifs_fid));
 	else

fs/cifs/smb2proto.h

@@ -70,6 +70,7 @@ extern int smb3_handle_read_data(struct TCP_Server_Info *server,
 				 struct mid_q_entry *mid);
 
 extern int open_shroot(unsigned int xid, struct cifs_tcon *tcon,
+		       const char *path,
 		       struct cifs_sb_info *cifs_sb,
 		       struct cached_fid **cfid);
 extern void close_shroot(struct cached_fid *cfid);