cifs: Add support for failover in smb2_reconnect()

After a successful failover in cifs_reconnect(), the smb2_reconnect()
function will make sure to reconnect every tcon to new target server.

For SMB2+.

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

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index f277bc5..336c116 100644 (file)
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -565,6 +565,8 @@ void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
 extern void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
                                unsigned int *len, unsigned int *offset);
 
+void extract_unc_hostname(const char *unc, const char **h, size_t *len);
+
 #ifdef CONFIG_CIFS_DFS_UPCALL
 static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
                               const char *old_path,

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 7c858d4..bee2030 100644 (file)
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -952,3 +952,20 @@ void rqst_page_get_length(struct smb_rqst *rqst, unsigned int page,
        else if (page == 0)
                *len = rqst->rq_pagesz - rqst->rq_offset;
 }
+
+void extract_unc_hostname(const char *unc, const char **h, size_t *len)
+{
+       const char *end;
+
+       /* skip initial slashes */
+       while (*unc && (*unc == '\\' || *unc == '/'))
+               unc++;
+
+       end = unc;
+
+       while (*end && !(*end == '\\' || *end == '/'))
+               end++;
+
+       *h = unc;
+       *len = end - unc;
+}

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 67ce339..e283590 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -50,6 +50,9 @@
 #include "cifs_spnego.h"
 #include "smbdirect.h"
 #include "trace.h"
+#ifdef CONFIG_CIFS_DFS_UPCALL
+#include "dfs_cache.h"
+#endif
 
 /*
  *  The following table defines the expected "StructureSize" of SMB2 requests
@@ -152,6 +155,77 @@ out:
        return;
 }
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static int __smb2_reconnect(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 SMB2_tcon(0, tcon->ses, tree, tcon, nlsc);
+       }
+
+       if (!tcon->dfs_path)
+               return SMB2_tcon(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 = SMB2_tcon(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 __smb2_reconnect(const struct nls_table *nlsc,
+                                  struct cifs_tcon *tcon)
+{
+       return SMB2_tcon(0, tcon->ses, tcon->treeName, tcon, nlsc);
+}
+#endif
+
 static int
 smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
 {
@@ -159,6 +233,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
        struct nls_table *nls_codepage;
        struct cifs_ses *ses;
        struct TCP_Server_Info *server;
+       int retries;
 
        /*
         * SMB2s NegProt, SessSetup, Logoff do not have tcon yet so
@@ -192,9 +267,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
        ses = tcon->ses;
        server = ses->server;
 
+       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) {
                /*
@@ -225,6 +303,9 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
                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
@@ -234,6 +315,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
                        cifs_dbg(FYI, "gave up waiting on reconnect in smb_init\n");
                        return -EHOSTDOWN;
                }
+               retries = server->nr_targets;
        }
 
        if (!tcon->ses->need_reconnect && !tcon->need_reconnect)
@@ -271,7 +353,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
        if (tcon->use_persistent)
                tcon->need_reopen_files = true;
 
-       rc = SMB2_tcon(0, tcon->ses, tcon->treeName, tcon, nls_codepage);
+       rc = __smb2_reconnect(nls_codepage, tcon);
        mutex_unlock(&tcon->ses->session_mutex);
 
        cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);