cifs: Always resolve hostname before reconnecting

In case a hostname resolves to a different IP address (e.g. long
running mounts), make sure to resolve it every time prior to calling
generic_ip_connect() in reconnect.

Suggested-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 80ef165d5f33f4dbd3282c2d7ccb42552faf0a60..69b9d5606ebac772ba590f08521106f46764e3f9 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -325,6 +325,53 @@ static int cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
                                        const char *devname, bool is_smb3);
 static char *extract_hostname(const char *unc);
 
+/*
+ * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may
+ * get their ip addresses changed at some point.
+ *
+ * This should be called with server->srv_mutex held.
+ */
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static int reconn_set_ipaddr(struct TCP_Server_Info *server)
+{
+       int rc;
+       int len;
+       char *unc, *ipaddr = NULL;
+
+       if (!server->hostname)
+               return -EINVAL;
+
+       len = strlen(server->hostname) + 3;
+
+       unc = kmalloc(len, GFP_KERNEL);
+       if (!unc) {
+               cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
+               return -ENOMEM;
+       }
+       snprintf(unc, len, "\\\\%s", server->hostname);
+
+       rc = dns_resolve_server_name_to_ip(unc, &ipaddr);
+       kfree(unc);
+
+       if (rc < 0) {
+               cifs_dbg(FYI, "%s: failed to resolve server part of %s to IP: %d\n",
+                        __func__, server->hostname, rc);
+               return rc;
+       }
+
+       rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
+                                 strlen(ipaddr));
+       kfree(ipaddr);
+
+       return !rc ? -1 : 0;
+}
+#else
+static inline int reconn_set_ipaddr(struct TCP_Server_Info *server)
+{
+       return 0;
+}
+#endif
+
 #ifdef CONFIG_CIFS_DFS_UPCALL
 struct super_cb_data {
        struct TCP_Server_Info *server;
@@ -366,10 +413,6 @@ static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
                                    struct dfs_cache_tgt_iterator **tgt_it)
 {
        const char *name;
-       int rc;
-       char *ipaddr = NULL;
-       char *unc;
-       int len;
 
        if (!cifs_sb || !cifs_sb->origin_fullpath || !tgt_list ||
            !server->nr_targets)
@@ -393,34 +436,6 @@ static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
        if (!server->hostname) {
                cifs_dbg(FYI, "%s: failed to extract hostname from target: %d\n",
                         __func__, -ENOMEM);
-               return;
-       }
-
-       len = strlen(server->hostname) + 3;
-
-       unc = kmalloc(len, GFP_KERNEL);
-       if (!unc) {
-               cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
-               return;
-       }
-       snprintf(unc, len, "\\\\%s", server->hostname);
-
-       rc = dns_resolve_server_name_to_ip(unc, &ipaddr);
-       kfree(unc);
-
-       if (rc < 0) {
-               cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
-                        __func__, server->hostname, rc);
-               return;
-       }
-
-       rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
-                                 strlen(ipaddr));
-       kfree(ipaddr);
-
-       if (!rc) {
-               cifs_dbg(FYI, "%s: failed to get ipaddr out of hostname\n",
-                        __func__);
        }
 }
 
@@ -567,6 +582,11 @@ cifs_reconnect(struct TCP_Server_Info *server)
                        reconn_inval_dfs_target(server, cifs_sb, &tgt_list,
                                                &tgt_it);
 #endif
+                       rc = reconn_set_ipaddr(server);
+                       if (rc) {
+                               cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",
+                                        __func__, rc);
+                       }
                        mutex_unlock(&server->srv_mutex);
                        msleep(3000);
                } else {