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authorShyam Prasad N <sprasad@microsoft.com>2023-10-13 14:40:09 +0300
committerSteve French <stfrench@microsoft.com>2023-11-10 18:33:19 +0300
commitee1d21794e55ab76505745d24101331552182002 (patch)
treefd10196528ecb09da9177f173cbed942591f644e
parent705fc522fe9d58848c253ee0948567060f36e2a7 (diff)
downloadlinux-ee1d21794e55ab76505745d24101331552182002.tar.xz
cifs: handle when server stops supporting multichannel
When a server stops supporting multichannel, we will keep attempting reconnects to the secondary channels today. Avoid this by freeing extra channels when negotiate returns no multichannel support. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
-rw-r--r--fs/smb/client/cifsglob.h1
-rw-r--r--fs/smb/client/cifsproto.h2
-rw-r--r--fs/smb/client/connect.c10
-rw-r--r--fs/smb/client/sess.c64
-rw-r--r--fs/smb/client/smb2pdu.c76
-rw-r--r--fs/smb/client/transport.c2
6 files changed, 145 insertions, 10 deletions
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 30763c68cc39..6ffbd81bd109 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -650,6 +650,7 @@ struct TCP_Server_Info {
bool noautotune; /* do not autotune send buf sizes */
bool nosharesock;
bool tcp_nodelay;
+ bool terminate;
unsigned int credits; /* send no more requests at once */
unsigned int max_credits; /* can override large 32000 default at mnt */
unsigned int in_flight; /* number of requests on the wire to server */
diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index 00ad41633e26..d87e2c26cce2 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -641,6 +641,8 @@ cifs_chan_needs_reconnect(struct cifs_ses *ses,
bool
cifs_chan_is_iface_active(struct cifs_ses *ses,
struct TCP_Server_Info *server);
+void
+cifs_disable_secondary_channels(struct cifs_ses *ses);
int
cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server);
int
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 1490547ec493..57c2a7df3457 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -219,6 +219,14 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry_safe(ses, nses, &pserver->smb_ses_list, smb_ses_list) {
+ /*
+ * if channel has been marked for termination, nothing to do
+ * for the channel. in fact, we cannot find the channel for the
+ * server. So safe to exit here
+ */
+ if (server->terminate)
+ break;
+
/* check if iface is still active */
if (!cifs_chan_is_iface_active(ses, server))
cifs_chan_update_iface(ses, server);
@@ -253,6 +261,8 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
spin_lock(&tcon->tc_lock);
tcon->status = TID_NEED_RECON;
spin_unlock(&tcon->tc_lock);
+
+ cancel_delayed_work(&tcon->query_interfaces);
}
if (ses->tcon_ipc) {
ses->tcon_ipc->need_reconnect = true;
diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
index 4e4cc0cd5206..0bb2ac929061 100644
--- a/fs/smb/client/sess.c
+++ b/fs/smb/client/sess.c
@@ -297,6 +297,60 @@ int cifs_try_adding_channels(struct cifs_ses *ses)
}
/*
+ * called when multichannel is disabled by the server.
+ * this always gets called from smb2_reconnect
+ * and cannot get called in parallel threads.
+ */
+void
+cifs_disable_secondary_channels(struct cifs_ses *ses)
+{
+ int i, chan_count;
+ struct TCP_Server_Info *server;
+ struct cifs_server_iface *iface;
+
+ spin_lock(&ses->chan_lock);
+ chan_count = ses->chan_count;
+ if (chan_count == 1)
+ goto done;
+
+ ses->chan_count = 1;
+
+ /* for all secondary channels reset the need reconnect bit */
+ ses->chans_need_reconnect &= 1;
+
+ for (i = 1; i < chan_count; i++) {
+ iface = ses->chans[i].iface;
+ server = ses->chans[i].server;
+
+ if (iface) {
+ spin_lock(&ses->iface_lock);
+ kref_put(&iface->refcount, release_iface);
+ ses->chans[i].iface = NULL;
+ iface->num_channels--;
+ if (iface->weight_fulfilled)
+ iface->weight_fulfilled--;
+ spin_unlock(&ses->iface_lock);
+ }
+
+ spin_unlock(&ses->chan_lock);
+ if (server && !server->terminate) {
+ server->terminate = true;
+ cifs_signal_cifsd_for_reconnect(server, false);
+ }
+ spin_lock(&ses->chan_lock);
+
+ if (server) {
+ ses->chans[i].server = NULL;
+ cifs_put_tcp_session(server, false);
+ }
+
+ }
+
+done:
+ spin_unlock(&ses->chan_lock);
+}
+
+/*
* update the iface for the channel if necessary.
* will return 0 when iface is updated, 1 if removed, 2 otherwise
* Must be called with chan_lock held.
@@ -595,14 +649,10 @@ cifs_ses_add_channel(struct cifs_ses *ses,
out:
if (rc && chan->server) {
- /*
- * we should avoid race with these delayed works before we
- * remove this channel
- */
- cancel_delayed_work_sync(&chan->server->echo);
- cancel_delayed_work_sync(&chan->server->reconnect);
+ cifs_put_tcp_session(chan->server, 0);
spin_lock(&ses->chan_lock);
+
/* we rely on all bits beyond chan_count to be clear */
cifs_chan_clear_need_reconnect(ses, chan->server);
ses->chan_count--;
@@ -612,8 +662,6 @@ out:
*/
WARN_ON(ses->chan_count < 1);
spin_unlock(&ses->chan_lock);
-
- cifs_put_tcp_session(chan->server, 0);
}
kfree(ctx->UNC);
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 0d4351e43069..2eb29fa278c3 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -164,6 +164,8 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
struct nls_table *nls_codepage = NULL;
struct cifs_ses *ses;
int xid;
+ struct TCP_Server_Info *pserver;
+ unsigned int chan_index;
/*
* SMB2s NegProt, SessSetup, Logoff do not have tcon yet so
@@ -224,6 +226,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
return -EAGAIN;
}
}
+
+ /* if server is marked for termination, cifsd will cleanup */
+ if (server->terminate) {
+ spin_unlock(&server->srv_lock);
+ return -EHOSTDOWN;
+ }
spin_unlock(&server->srv_lock);
again:
@@ -243,11 +251,23 @@ again:
mutex_lock(&ses->session_mutex);
/*
+ * if this is called by delayed work, and the channel has been disabled
+ * in parallel, the delayed work can continue to execute in parallel
+ * there's a chance that this channel may not exist anymore
+ */
+ spin_lock(&server->srv_lock);
+ if (server->tcpStatus == CifsExiting) {
+ spin_unlock(&server->srv_lock);
+ mutex_unlock(&ses->session_mutex);
+ rc = -EHOSTDOWN;
+ goto out;
+ }
+
+ /*
* Recheck after acquire mutex. If another thread is negotiating
* and the server never sends an answer the socket will be closed
* and tcpStatus set to reconnect.
*/
- spin_lock(&server->srv_lock);
if (server->tcpStatus == CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
mutex_unlock(&ses->session_mutex);
@@ -284,6 +304,53 @@ again:
rc = cifs_negotiate_protocol(0, ses, server);
if (!rc) {
+ /*
+ * if server stopped supporting multichannel
+ * and the first channel reconnected, disable all the others.
+ */
+ if (ses->chan_count > 1 &&
+ !(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+ if (SERVER_IS_CHAN(server)) {
+ cifs_dbg(VFS, "server %s does not support " \
+ "multichannel anymore. skipping secondary channel\n",
+ ses->server->hostname);
+
+ spin_lock(&ses->chan_lock);
+ chan_index = cifs_ses_get_chan_index(ses, server);
+ if (chan_index == CIFS_INVAL_CHAN_INDEX) {
+ spin_unlock(&ses->chan_lock);
+ goto skip_terminate;
+ }
+
+ ses->chans[chan_index].server = NULL;
+ spin_unlock(&ses->chan_lock);
+
+ /*
+ * the above reference of server by channel
+ * needs to be dropped without holding chan_lock
+ * as cifs_put_tcp_session takes a higher lock
+ * i.e. cifs_tcp_ses_lock
+ */
+ cifs_put_tcp_session(server, 1);
+
+ server->terminate = true;
+ cifs_signal_cifsd_for_reconnect(server, false);
+
+ /* mark primary server as needing reconnect */
+ pserver = server->primary_server;
+ cifs_signal_cifsd_for_reconnect(pserver, false);
+
+skip_terminate:
+ mutex_unlock(&ses->session_mutex);
+ rc = -EHOSTDOWN;
+ goto out;
+ } else {
+ cifs_server_dbg(VFS, "does not support " \
+ "multichannel anymore. disabling all other channels\n");
+ cifs_disable_secondary_channels(ses);
+ }
+ }
+
rc = cifs_setup_session(0, ses, server, nls_codepage);
if ((rc == -EACCES) && !tcon->retry) {
mutex_unlock(&ses->session_mutex);
@@ -3836,6 +3903,13 @@ void smb2_reconnect_server(struct work_struct *work)
/* Prevent simultaneous reconnects that can corrupt tcon->rlist list */
mutex_lock(&pserver->reconnect_mutex);
+ /* if the server is marked for termination, drop the ref count here */
+ if (server->terminate) {
+ cifs_put_tcp_session(server, true);
+ mutex_unlock(&pserver->reconnect_mutex);
+ return;
+ }
+
INIT_LIST_HEAD(&tmp_list);
INIT_LIST_HEAD(&tmp_ses_list);
cifs_dbg(FYI, "Reconnecting tcons and channels\n");
diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c
index d553b7a54621..4f717ad7c21b 100644
--- a/fs/smb/client/transport.c
+++ b/fs/smb/client/transport.c
@@ -1023,7 +1023,7 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
spin_lock(&ses->chan_lock);
for (i = 0; i < ses->chan_count; i++) {
server = ses->chans[i].server;
- if (!server)
+ if (!server || server->terminate)
continue;
/*