cifs: Add support for failover in cifs_reconnect_tcon()

After a successful failover, the cifs_reconnect_tcon() function will
make sure to reconnect every tcon to new target server.

Same as previous commit but for SMB1 codepath.
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifssmb.c

@@ -44,6 +44,9 @@
 #include "cifs_debug.h"
 #include "fscache.h"
 #include "smbdirect.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
 
 #ifdef CONFIG_CIFS_POSIX
 static struct {
@@ -118,6 +121,77 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	 */
 }
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static int __cifs_reconnect_tcon(const struct nls_table *nlsc,
+				 struct cifs_tcon *tcon)
+{
+	int rc;
+	struct dfs_cache_tgt_list tl;
+	struct dfs_cache_tgt_iterator *it = NULL;
+	char tree[MAX_TREE_SIZE + 1];
+	const char *tcp_host;
+	size_t tcp_host_len;
+	const char *dfs_host;
+	size_t dfs_host_len;
+
+	if (tcon->ipc) {
+		snprintf(tree, sizeof(tree), "\\\\%s\\IPC$",
+			 tcon->ses->server->hostname);
+		return CIFSTCon(0, tcon->ses, tree, tcon, nlsc);
+	}
+
+	if (!tcon->dfs_path)
+		return CIFSTCon(0, tcon->ses, tcon->treeName, tcon, nlsc);
+
+	rc = dfs_cache_noreq_find(tcon->dfs_path + 1, NULL, &tl);
+	if (rc)
+		return rc;
+
+	extract_unc_hostname(tcon->ses->server->hostname, &tcp_host,
+			     &tcp_host_len);
+
+	for (it = dfs_cache_get_tgt_iterator(&tl); it;
+	     it = dfs_cache_get_next_tgt(&tl, it)) {
+		const char *tgt = dfs_cache_get_tgt_name(it);
+
+		extract_unc_hostname(tgt, &dfs_host, &dfs_host_len);
+
+		if (dfs_host_len != tcp_host_len
+		    || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
+			cifs_dbg(FYI, "%s: skipping %.*s, doesn't match %.*s",
+				 __func__,
+				 (int)dfs_host_len, dfs_host,
+				 (int)tcp_host_len, tcp_host);
+			continue;
+		}
+
+		snprintf(tree, sizeof(tree), "\\%s", tgt);
+
+		rc = CIFSTCon(0, tcon->ses, tree, tcon, nlsc);
+		if (!rc)
+			break;
+		if (rc == -EREMOTE)
+			break;
+	}
+
+	if (!rc) {
+		if (it)
+			rc = dfs_cache_noreq_update_tgthint(tcon->dfs_path + 1,
+							    it);
+		else
+			rc = -ENOENT;
+	}
+	dfs_cache_free_tgts(&tl);
+	return rc;
+}
+#else
+static inline int __cifs_reconnect_tcon(const struct nls_table *nlsc,
+					struct cifs_tcon *tcon)
+{
+	return CIFSTCon(0, tcon->ses, tcon->treeName, tcon, nlsc);
+}
+#endif
+
 /* reconnect the socket, tcon, and smb session if needed */
 static int
 cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
@@ -126,6 +200,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	struct cifs_ses *ses;
 	struct TCP_Server_Info *server;
 	struct nls_table *nls_codepage;
+	int retries;
 
 	/*
 	 * SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@@ -152,9 +227,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		}
 	}
 
+	retries = server->nr_targets;
+
 	/*
-	 * Give demultiplex thread up to 10 seconds to reconnect, should be
-	 * greater than cifs socket timeout which is 7 seconds
+	 * Give demultiplex thread up to 10 seconds to each target available for
+	 * reconnect -- should be greater than cifs socket timeout which is 7
+	 * seconds.
 	 */
 	while (server->tcpStatus == CifsNeedReconnect) {
 		rc = wait_event_interruptible_timeout(server->response_q,
@@ -170,6 +248,9 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		if (server->tcpStatus != CifsNeedReconnect)
 			break;
 
+		if (--retries)
+			continue;
+
 		/*
 		 * on "soft" mounts we wait once. Hard mounts keep
 		 * retrying until process is killed or server comes
@@ -179,6 +260,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 			cifs_dbg(FYI, "gave up waiting on reconnect in smb_init\n");
 			return -EHOSTDOWN;
 		}
+		retries = server->nr_targets;
 	}
 
 	if (!ses->need_reconnect && !tcon->need_reconnect)
@@ -214,7 +296,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	}
 
 	cifs_mark_open_files_invalid(tcon);
-	rc = CIFSTCon(0, ses, tcon->treeName, tcon, nls_codepage);
+	rc = __cifs_reconnect_tcon(nls_codepage, tcon);
 	mutex_unlock(&ses->session_mutex);
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);