[PATCH v3 10/11] cifs: Handle witness client move notification

Samuel Cabrero
2020-10-30T11:52:56Z

This message is sent to tell a client to close its current connection
and connect to the specified address.

Signed-off-by: Samuel Cabrero <scabrero@suse.de>
---
fs/cifs/cifs_swn.c | 140 ++++++++++++++++++++++++++++++++++++++++++++-
fs/cifs/cifsglob.h | 4 ++
fs/cifs/connect.c | 26 +++++++--
3 files changed, 162 insertions(+), 8 deletions(-)

diff --git a/fs/cifs/cifs_swn.c b/fs/cifs/cifs_swn.c
index 93e31e4a9d99..b71b05638b1c 100644
--- a/fs/cifs/cifs_swn.c
+++ b/fs/cifs/cifs_swn.c
@@ -78,6 +78,7 @@ static int cifs_swn_send_register_message(struct cifs_swn_reg *swnreg)
struct sk_buff *skb;
struct genlmsghdr *hdr;
enum securityEnum authtype;
+ struct sockaddr_storage *addr;
int ret;

skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
@@ -104,8 +105,18 @@ static int cifs_swn_send_register_message(struct cifs_swn_reg *swnreg)
if (ret < 0)
goto nlmsg_fail;

- ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage),
- &swnreg->tcon->ses->server->dstaddr);
+ /*
+ * If there is an address stored use it instead of the server address, because we are
+ * in the process of reconnecting to it after a share has been moved or we have been
+ * told to switch to it (client move message). In these cases we unregister from the
+ * server address and register to the new address when we receive the notification.
+ */
+ if (swnreg->tcon->ses->server->use_swn_dstaddr)
+ addr = &swnreg->tcon->ses->server->swn_dstaddr;
+ else
+ addr = &swnreg->tcon->ses->server->dstaddr;
+
+ ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage), addr);
if (ret < 0)
goto nlmsg_fail;

@@ -409,6 +420,120 @@ static int cifs_swn_resource_state_changed(struct cifs_swn_reg *swnreg, const ch
return 0;
}

+static bool cifs_sockaddr_equal(struct sockaddr_storage *addr1, struct sockaddr_storage *addr2)
+{
+ if (addr1->ss_family != addr2->ss_family)
+ return false;
+
+ if (addr1->ss_family == AF_INET) {
+ return (memcmp(&((const struct sockaddr_in *)addr1)->sin_addr,
+ &((const struct sockaddr_in *)addr2)->sin_addr,
+ sizeof(struct in_addr)) == 0);
+ }
+
+ if (addr1->ss_family == AF_INET6) {
+ return (memcmp(&((const struct sockaddr_in6 *)addr1)->sin6_addr,
+ &((const struct sockaddr_in6 *)addr2)->sin6_addr,
+ sizeof(struct in6_addr)) == 0);
+ }
+
+ return false;
+}
+
+static int cifs_swn_store_swn_addr(const struct sockaddr_storage *new,
+ const struct sockaddr_storage *old,
+ struct sockaddr_storage *dst)
+{
+ __be16 port;
+
+ if (old->ss_family == AF_INET) {
+ struct sockaddr_in *ipv4 = (struct sockaddr_in *)old;
+
+ port = ipv4->sin_port;
+ }
+
+ if (old->ss_family == AF_INET6) {
+ struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)old;
+
+ port = ipv6->sin6_port;
+ }
+
+ if (new->ss_family == AF_INET) {
+ struct sockaddr_in *ipv4 = (struct sockaddr_in *)new;
+
+ ipv4->sin_port = port;
+ }
+
+ if (new->ss_family == AF_INET6) {
+ struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)new;
+
+ ipv6->sin6_port = port;
+ }
+
+ *dst = *new;
+
+ return 0;
+}
+
+static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *addr)
+{
+ /* Store the reconnect address */
+ mutex_lock(&tcon->ses->server->srv_mutex);
+ if (!cifs_sockaddr_equal(&tcon->ses->server->dstaddr, addr)) {
+ int ret;
+
+ ret = cifs_swn_store_swn_addr(addr, &tcon->ses->server->dstaddr,
+ &tcon->ses->server->swn_dstaddr);
+ if (ret < 0) {
+ cifs_dbg(VFS, "%s: failed to store address: %d\n", __func__, ret);
+ return ret;
+ }
+ tcon->ses->server->use_swn_dstaddr = true;
+
+ /*
+ * Unregister to stop receiving notifications for the old IP address.
+ */
+ ret = cifs_swn_unregister(tcon);
+ if (ret < 0) {
+ cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
+ __func__, ret);
+ return ret;
+ }
+
+ /*
+ * And register to receive notifications for the new IP address now that we have
+ * stored the new address.
+ */
+ ret = cifs_swn_register(tcon);
+ if (ret < 0) {
+ cifs_dbg(VFS, "%s: Failed to register for witness notifications: %d\n",
+ __func__, ret);
+ return ret;
+ }
+
+ spin_lock(&GlobalMid_Lock);
+ if (tcon->ses->server->tcpStatus != CifsExiting)
+ tcon->ses->server->tcpStatus = CifsNeedReconnect;
+ spin_unlock(&GlobalMid_Lock);
+ }
+ mutex_unlock(&tcon->ses->server->srv_mutex);
+
+ return 0;
+}
+
+static int cifs_swn_client_move(struct cifs_swn_reg *swnreg, struct sockaddr_storage *addr)
+{
+ struct sockaddr_in *ipv4 = (struct sockaddr_in *)addr;
+ struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)addr;
+
+ if (addr->ss_family == AF_INET)
+ cifs_dbg(FYI, "%s: move to %pI4\n", __func__, &ipv4->sin_addr);
+ else if (addr->ss_family == AF_INET6)
+ cifs_dbg(FYI, "%s: move to %pI6\n", __func__, &ipv6->sin6_addr);
+
+ return cifs_swn_reconnect(swnreg->tcon, addr);
+}
+
int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
{
struct cifs_swn_reg *swnreg;
@@ -457,6 +582,17 @@ int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
}
return cifs_swn_resource_state_changed(swnreg, name, state);
}
+ case CIFS_SWN_NOTIFICATION_CLIENT_MOVE: {
+ struct sockaddr_storage addr;
+
+ if (info->attrs[CIFS_GENL_ATTR_SWN_IP]) {
+ nla_memcpy(&addr, info->attrs[CIFS_GENL_ATTR_SWN_IP], sizeof(addr));
+ } else {
+ cifs_dbg(FYI, "%s: missing IP address attribute\n", __func__);
+ return -EINVAL;
+ }
+ return cifs_swn_client_move(swnreg, &addr);
+ }
default:
cifs_dbg(FYI, "%s: unknown notification type %d\n", __func__, type);
break;
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index f45b7c0fbceb..d7f43cec0f13 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -779,6 +779,10 @@ struct TCP_Server_Info {
int nr_targets;
bool noblockcnt; /* use non-blocking connect() */
bool is_channel; /* if a session channel */
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ bool use_swn_dstaddr;
+ struct sockaddr_storage swn_dstaddr;
+#endif
};

struct cifs_credits {
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 14bbec0aeccf..0da10d199f47 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -520,13 +520,24 @@ cifs_reconnect(struct TCP_Server_Info *server)
try_to_freeze();

mutex_lock(&server->srv_mutex);
+
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ if (server->use_swn_dstaddr) {
+ server->dstaddr = server->swn_dstaddr;
+ } else {
+#endif
+
#ifdef CONFIG_CIFS_DFS_UPCALL
- /*
- * Set up next DFS target server (if any) for reconnect. If DFS
- * feature is disabled, then we will retry last server we
- * connected to before.
- */
- reconn_set_next_dfs_target(server, cifs_sb, &tgt_list, &tgt_it);
+ /*
+ * Set up next DFS target server (if any) for reconnect. If DFS
+ * feature is disabled, then we will retry last server we
+ * connected to before.
+ */
+ reconn_set_next_dfs_target(server, cifs_sb, &tgt_list, &tgt_it);
+#endif
+
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ }
#endif

if (cifs_rdma_enabled(server))
@@ -544,6 +555,9 @@ cifs_reconnect(struct TCP_Server_Info *server)
if (server->tcpStatus != CifsExiting)
server->tcpStatus = CifsNeedNegotiate;
spin_unlock(&GlobalMid_Lock);
+#ifdef CONFIG_CIFS_SWN_UPCALL
+ server->use_swn_dstaddr = false;
+#endif
mutex_unlock(&server->srv_mutex);
}
} while (server->tcpStatus == CifsNeedReconnect);
--
2.29.0