cifs: don't block in dfs_cache_noreq_update_tgthint()

Avoid blocking in dfs_cache_noreq_update_tgthint() while reconnecting
servers or tcons as the cache refresh worker or new mounts might
already be updating their targets.

Move some more dfs related code out of connect.c while at it.

Signed-off-by: Paulo Alcantara (SUSE) <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Paulo Alcantara

fs/cifs/connect.c

@@ -529,9 +529,7 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server)
 		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 	} while (server->tcpStatus == CifsNeedReconnect);
 
-	if (target_hint)
-		dfs_cache_noreq_update_tgthint(refpath, target_hint);
-
+	dfs_cache_noreq_update_tgthint(refpath, target_hint);
 	dfs_cache_free_tgts(&tl);
 
 	/* Need to set up echo worker again once connection has been established */
@@ -4079,265 +4077,7 @@ cifs_prune_tlinks(struct work_struct *work)
 				TLINK_IDLE_EXPIRE);
 }
 
-#ifdef CONFIG_CIFS_DFS_UPCALL
-/* Update dfs referral path of superblock */
-static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb_info *cifs_sb,
-				  const char *target)
-{
-	int rc = 0;
-	size_t len = strlen(target);
-	char *refpath, *npath;
-
-	if (unlikely(len < 2 || *target != '\\'))
-		return -EINVAL;
-
-	if (target[1] == '\\') {
-		len += 1;
-		refpath = kmalloc(len, GFP_KERNEL);
-		if (!refpath)
-			return -ENOMEM;
-
-		scnprintf(refpath, len, "%s", target);
-	} else {
-		len += sizeof("\\");
-		refpath = kmalloc(len, GFP_KERNEL);
-		if (!refpath)
-			return -ENOMEM;
-
-		scnprintf(refpath, len, "\\%s", target);
-	}
-
-	npath = dfs_cache_canonical_path(refpath, cifs_sb->local_nls, cifs_remap(cifs_sb));
-	kfree(refpath);
-
-	if (IS_ERR(npath)) {
-		rc = PTR_ERR(npath);
-	} else {
-		mutex_lock(&server->refpath_lock);
-		kfree(server->leaf_fullpath);
-		server->leaf_fullpath = npath;
-		mutex_unlock(&server->refpath_lock);
-		server->current_fullpath = server->leaf_fullpath;
-	}
-	return rc;
-}
-
-static int target_share_matches_server(struct TCP_Server_Info *server, const char *tcp_host,
-				       size_t tcp_host_len, char *share, bool *target_match)
-{
-	int rc = 0;
-	const char *dfs_host;
-	size_t dfs_host_len;
-
-	*target_match = true;
-	extract_unc_hostname(share, &dfs_host, &dfs_host_len);
-
-	/* Check if hostnames or addresses match */
-	if (dfs_host_len != tcp_host_len || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
-		cifs_dbg(FYI, "%s: %.*s doesn't match %.*s\n", __func__, (int)dfs_host_len,
-			 dfs_host, (int)tcp_host_len, tcp_host);
-		rc = match_target_ip(server, dfs_host, dfs_host_len, target_match);
-		if (rc)
-			cifs_dbg(VFS, "%s: failed to match target ip: %d\n", __func__, rc);
-	}
-	return rc;
-}
-
-static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
-				     struct cifs_sb_info *cifs_sb, char *tree, bool islink,
-				     struct dfs_cache_tgt_list *tl)
-{
-	int rc;
-	struct TCP_Server_Info *server = tcon->ses->server;
-	const struct smb_version_operations *ops = server->ops;
-	struct cifs_ses *root_ses = CIFS_DFS_ROOT_SES(tcon->ses);
-	struct cifs_tcon *ipc = root_ses->tcon_ipc;
-	char *share = NULL, *prefix = NULL;
-	const char *tcp_host;
-	size_t tcp_host_len;
-	struct dfs_cache_tgt_iterator *tit;
-	bool target_match;
-
-	extract_unc_hostname(server->hostname, &tcp_host, &tcp_host_len);
-
-	tit = dfs_cache_get_tgt_iterator(tl);
-	if (!tit) {
-		rc = -ENOENT;
-		goto out;
-	}
-
-	/* Try to tree connect to all dfs targets */
-	for (; tit; tit = dfs_cache_get_next_tgt(tl, tit)) {
-		const char *target = dfs_cache_get_tgt_name(tit);
-		struct dfs_cache_tgt_list ntl = DFS_CACHE_TGT_LIST_INIT(ntl);
-
-		kfree(share);
-		kfree(prefix);
-		share = prefix = NULL;
-
-		/* Check if share matches with tcp ses */
-		rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix);
-		if (rc) {
-			cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc);
-			break;
-		}
-
-		rc = target_share_matches_server(server, tcp_host, tcp_host_len, share,
-						 &target_match);
-		if (rc)
-			break;
-		if (!target_match) {
-			rc = -EHOSTUNREACH;
-			continue;
-		}
-
-		if (ipc->need_reconnect) {
-			scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
-			rc = ops->tree_connect(xid, ipc->ses, tree, ipc, cifs_sb->local_nls);
-			if (rc)
-				break;
-		}
-
-		scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
-		if (!islink) {
-			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
-			break;
-		}
-		/*
-		 * If no dfs referrals were returned from link target, then just do a TREE_CONNECT
-		 * to it.  Otherwise, cache the dfs referral and then mark current tcp ses for
-		 * reconnect so either the demultiplex thread or the echo worker will reconnect to
-		 * newly resolved target.
-		 */
-		if (dfs_cache_find(xid, root_ses, cifs_sb->local_nls, cifs_remap(cifs_sb), target,
-				   NULL, &ntl)) {
-			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
-			if (rc)
-				continue;
-			rc = dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
-			if (!rc)
-				rc = cifs_update_super_prepath(cifs_sb, prefix);
-		} else {
-			/* Target is another dfs share */
-			rc = update_server_fullpath(server, cifs_sb, target);
-			dfs_cache_free_tgts(tl);
-
-			if (!rc) {
-				rc = -EREMOTE;
-				list_replace_init(&ntl.tl_list, &tl->tl_list);
-			} else
-				dfs_cache_free_tgts(&ntl);
-		}
-		break;
-	}
-
-out:
-	kfree(share);
-	kfree(prefix);
-
-	return rc;
-}
-
-static int tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
-				   struct cifs_sb_info *cifs_sb, char *tree, bool islink,
-				   struct dfs_cache_tgt_list *tl)
-{
-	int rc;
-	int num_links = 0;
-	struct TCP_Server_Info *server = tcon->ses->server;
-
-	do {
-		rc = __tree_connect_dfs_target(xid, tcon, cifs_sb, tree, islink, tl);
-		if (!rc || rc != -EREMOTE)
-			break;
-	} while (rc = -ELOOP, ++num_links < MAX_NESTED_LINKS);
-	/*
-	 * If we couldn't tree connect to any targets from last referral path, then retry from
-	 * original referral path.
-	 */
-	if (rc && server->current_fullpath != server->origin_fullpath) {
-		server->current_fullpath = server->origin_fullpath;
-		cifs_signal_cifsd_for_reconnect(server, true);
-	}
-
-	dfs_cache_free_tgts(tl);
-	return rc;
-}
-
-int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
-{
-	int rc;
-	struct TCP_Server_Info *server = tcon->ses->server;
-	const struct smb_version_operations *ops = server->ops;
-	struct super_block *sb = NULL;
-	struct cifs_sb_info *cifs_sb;
-	struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
-	char *tree;
-	struct dfs_info3_param ref = {0};
-
-	/* only send once per connect */
-	spin_lock(&tcon->tc_lock);
-	if (tcon->ses->ses_status != SES_GOOD ||
-	    (tcon->status != TID_NEW &&
-	    tcon->status != TID_NEED_TCON)) {
-		spin_unlock(&tcon->tc_lock);
-		return 0;
-	}
-	tcon->status = TID_IN_TCON;
-	spin_unlock(&tcon->tc_lock);
-
-	tree = kzalloc(MAX_TREE_SIZE, GFP_KERNEL);
-	if (!tree) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
-	if (tcon->ipc) {
-		scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
-		rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc);
-		goto out;
-	}
-
-	sb = cifs_get_tcp_super(server);
-	if (IS_ERR(sb)) {
-		rc = PTR_ERR(sb);
-		cifs_dbg(VFS, "%s: could not find superblock: %d\n", __func__, rc);
-		goto out;
-	}
-
-	cifs_sb = CIFS_SB(sb);
-
-	/* If it is not dfs or there was no cached dfs referral, then reconnect to same share */
-	if (!server->current_fullpath ||
-	    dfs_cache_noreq_find(server->current_fullpath + 1, &ref, &tl)) {
-		rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls);
-		goto out;
-	}
-
-	rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, ref.server_type == DFS_TYPE_LINK,
-				     &tl);
-	free_dfs_info_param(&ref);
-
-out:
-	kfree(tree);
-	cifs_put_tcp_super(sb);
-
-	if (rc) {
-		spin_lock(&tcon->tc_lock);
-		if (tcon->status == TID_IN_TCON)
-			tcon->status = TID_NEED_TCON;
-		spin_unlock(&tcon->tc_lock);
-	} else {
-		spin_lock(&tcon->tc_lock);
-		if (tcon->status == TID_IN_TCON)
-			tcon->status = TID_GOOD;
-		spin_unlock(&tcon->tc_lock);
-		tcon->need_reconnect = false;
-	}
-
-	return rc;
-}
-#else
+#ifndef CONFIG_CIFS_DFS_UPCALL
 int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
 {
 	int rc;