cifs: use origin fullpath for automounts

commit 7ad54b98fc upstream.

Use TCP_Server_Info::origin_fullpath instead of cifs_tcon::tree_name
when building source paths for automounts as it will be useful for
domain-based DFS referrals where the connections and referrals would
get either re-used from the cache or re-created when chasing the dfs
link.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
[apanyaki: backport to v6.1-stable]
Signed-off-by: Andrew Paniakin <apanyaki@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/smb/client/cifs_dfs_ref.c

@@ -258,6 +258,31 @@ compose_mount_options_err:
 	goto compose_mount_options_out;
 }
 
+static int set_dest_addr(struct smb3_fs_context *ctx, const char *full_path)
+{
+	struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
+	char *str_addr = NULL;
+	int rc;
+
+	rc = dns_resolve_server_name_to_ip(full_path, &str_addr, NULL);
+	if (rc < 0)
+		goto out;
+
+	rc = cifs_convert_address(addr, str_addr, strlen(str_addr));
+	if (!rc) {
+		cifs_dbg(FYI, "%s: failed to convert ip address\n", __func__);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	cifs_set_port(addr, ctx->port);
+	rc = 0;
+
+out:
+	kfree(str_addr);
+	return rc;
+}
+
 /*
  * Create a vfsmount that we can automount
  */
@@ -295,8 +320,7 @@ static struct vfsmount *cifs_dfs_do_automount(struct path *path)
 	ctx = smb3_fc2context(fc);
 
 	page = alloc_dentry_path();
-	/* always use tree name prefix */
+	full_path = dfs_get_automount_devname(mntpt, page);
-	full_path = build_path_from_dentry_optional_prefix(mntpt, page, true);
 	if (IS_ERR(full_path)) {
 		mnt = ERR_CAST(full_path);
 		goto out;
@@ -315,6 +339,12 @@ static struct vfsmount *cifs_dfs_do_automount(struct path *path)
 		goto out;
 	}
 
+	rc = set_dest_addr(ctx, full_path);
+	if (rc) {
+		mnt = ERR_PTR(rc);
+		goto out;
+	}
+
 	rc = smb3_parse_devname(full_path, ctx);
 	if (!rc)
 		mnt = fc_mount(fc);

fs/smb/client/cifsproto.h

@@ -57,8 +57,29 @@ extern void exit_cifs_idmap(void);
 extern int init_cifs_spnego(void);
 extern void exit_cifs_spnego(void);
 extern const char *build_path_from_dentry(struct dentry *, void *);
+char *__build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+					       const char *tree, int tree_len,
+					       bool prefix);
 extern char *build_path_from_dentry_optional_prefix(struct dentry *direntry,
 						    void *page, bool prefix);
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+	struct TCP_Server_Info *server = tcon->ses->server;
+
+	if (unlikely(!server->origin_fullpath))
+		return ERR_PTR(-EREMOTE);
+
+	return __build_path_from_dentry_optional_prefix(dentry, page,
+							server->origin_fullpath,
+							strlen(server->origin_fullpath),
+							true);
+}
+#endif
+
 static inline void *alloc_dentry_path(void)
 {
 	return __getname();

fs/smb/client/dir.c

@@ -78,14 +78,13 @@ build_path_from_dentry(struct dentry *direntry, void *page)
 						      prefix);
 }
 
-char *
+char *__build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
-build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+					       const char *tree, int tree_len,
-				       bool prefix)
+					       bool prefix)
 {
 	int dfsplen;
 	int pplen = 0;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
-	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 	char dirsep = CIFS_DIR_SEP(cifs_sb);
 	char *s;
 
@@ -93,7 +92,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
 		return ERR_PTR(-ENOMEM);
 
 	if (prefix)
-		dfsplen = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1);
+		dfsplen = strnlen(tree, tree_len + 1);
 	else
 		dfsplen = 0;
 
@@ -123,7 +122,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
 	}
 	if (dfsplen) {
 		s -= dfsplen;
-		memcpy(s, tcon->tree_name, dfsplen);
+		memcpy(s, tree, dfsplen);
 		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
 			int i;
 			for (i = 0; i < dfsplen; i++) {
@@ -135,6 +134,16 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
 	return s;
 }
 
+char *build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+					     bool prefix)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+
+	return __build_path_from_dentry_optional_prefix(direntry, page, tcon->tree_name,
+							MAX_TREE_SIZE, prefix);
+}
+
 /*
  * Don't allow path components longer than the server max.
  * Don't allow the separator character in a path component.