cifs: use the chans_need_reconnect bitmap for reconnect status

We use the concept of "binding" when one of the secondary channel
is in the process of connecting/reconnecting to the server. Till this
binding process completes, and the channel is bound to an existing session,
we redirect traffic from other established channels on the binding channel,
effectively blocking all traffic till individual channels get reconnected.

With my last set of commits, we can get rid of this binding serialization.
We now have a bitmap of connection states for each channel. We will use
this bitmap instead for tracking channel status.

Having a bitmap also now enables us to keep the session alive, as long
as even a single channel underneath is alive.

Unfortunately, this also meant that we need to supply the tcp connection
info for the channel during all negotiate and session setup functions.
These changes have resulted in a slightly bigger code churn.
However, I expect perf and robustness improvements in the mchan scenario
after this change.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 59 insertions, 64 deletions

diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index ba8543ccb298..b121a2591e69 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -310,7 +310,7 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 
 	mutex_lock(&ses->session_mutex);
 	spin_lock(&ses->chan_lock);
-	chan = ses->binding_chan = &ses->chans[ses->chan_count];
+	chan = &ses->chans[ses->chan_count];
 	chan->server = chan_server;
 	if (IS_ERR(chan->server)) {
 		rc = PTR_ERR(chan->server);
@@ -318,6 +318,12 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 		spin_unlock(&ses->chan_lock);
 		goto out;
 	}
+	ses->chan_count++;
+	atomic_set(&ses->chan_seq, 0);
+
+	/* Mark this channel as needing connect/setup */
+	cifs_chan_set_need_reconnect(ses, chan->server);
+
 	spin_unlock(&ses->chan_lock);
 
 	/*
@@ -331,41 +337,17 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 		goto out;
 	}
 
-	ses->binding = true;
-	rc = cifs_negotiate_protocol(xid, ses);
-	if (rc)
-		goto out;
-
-	rc = cifs_setup_session(xid, ses, cifs_sb->local_nls);
-	if (rc)
-		goto out;
-
-	/* success, put it on the list
-	 * XXX: sharing ses between 2 tcp servers is not possible, the
-	 * way "internal" linked lists works in linux makes element
-	 * only able to belong to one list
-	 *
-	 * the binding session is already established so the rest of
-	 * the code should be able to look it up, no need to add the
-	 * ses to the new server.
-	 */
-
-	spin_lock(&ses->chan_lock);
-	ses->chan_count++;
-	atomic_set(&ses->chan_seq, 0);
-
-	/* Mark this channel as needing connect/setup */
-	cifs_chan_set_need_reconnect(ses, chan->server);
-	spin_unlock(&ses->chan_lock);
+	rc = cifs_negotiate_protocol(xid, ses, chan->server);
+	if (!rc)
+		rc = cifs_setup_session(xid, ses, chan->server, cifs_sb->local_nls);
 
 out:
-	ses->binding = false;
-	ses->binding_chan = NULL;
-
 	if (rc && chan->server) {
+		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--;
+		spin_unlock(&ses->chan_lock);
 	}
 
 	mutex_unlock(&ses->session_mutex);
@@ -389,7 +371,9 @@ void cifs_ses_mark_for_reconnect(struct cifs_ses *ses)
 	}
 }
 
-static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
+static __u32 cifs_ssetup_hdr(struct cifs_ses *ses,
+			     struct TCP_Server_Info *server,
+			     SESSION_SETUP_ANDX *pSMB)
 {
 	__u32 capabilities = 0;
 
@@ -402,7 +386,7 @@ static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 	pSMB->req.MaxBufferSize = cpu_to_le16(min_t(u32,
 					CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4,
 					USHRT_MAX));
-	pSMB->req.MaxMpxCount = cpu_to_le16(ses->server->maxReq);
+	pSMB->req.MaxMpxCount = cpu_to_le16(server->maxReq);
 	pSMB->req.VcNumber = cpu_to_le16(1);
 
 	/* Now no need to set SMBFLG_CASELESS or obsolete CANONICAL PATH */
@@ -413,7 +397,7 @@ static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 	capabilities = CAP_LARGE_FILES | CAP_NT_SMBS | CAP_LEVEL_II_OPLOCKS |
 			CAP_LARGE_WRITE_X | CAP_LARGE_READ_X;
 
-	if (ses->server->sign)
+	if (server->sign)
 		pSMB->req.hdr.Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 
 	if (ses->capabilities & CAP_UNICODE) {
@@ -776,10 +760,10 @@ static inline void cifs_security_buffer_from_str(SECURITY_BUFFER *pbuf,
 int build_ntlmssp_negotiate_blob(unsigned char **pbuffer,
 				 u16 *buflen,
 				 struct cifs_ses *ses,
+				 struct TCP_Server_Info *server,
 				 const struct nls_table *nls_cp)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	NEGOTIATE_MESSAGE *sec_blob;
 	__u32 flags;
 	unsigned char *tmp;
@@ -833,6 +817,7 @@ setup_ntlm_neg_ret:
 int build_ntlmssp_auth_blob(unsigned char **pbuffer,
 					u16 *buflen,
 				   struct cifs_ses *ses,
+				   struct TCP_Server_Info *server,
 				   const struct nls_table *nls_cp)
 {
 	int rc;
@@ -969,6 +954,7 @@ cifs_select_sectype(struct TCP_Server_Info *server, enum securityEnum requested)
 struct sess_data {
 	unsigned int xid;
 	struct cifs_ses *ses;
+	struct TCP_Server_Info *server;
 	struct nls_table *nls_cp;
 	void (*func)(struct sess_data *);
 	int result;
@@ -1035,35 +1021,34 @@ static int
 sess_establish_session(struct sess_data *sess_data)
 {
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 
-	mutex_lock(&ses->server->srv_mutex);
-	if (!ses->server->session_estab) {
-		if (ses->server->sign) {
-			ses->server->session_key.response =
+	mutex_lock(&server->srv_mutex);
+	if (!server->session_estab) {
+		if (server->sign) {
+			server->session_key.response =
 				kmemdup(ses->auth_key.response,
 				ses->auth_key.len, GFP_KERNEL);
-			if (!ses->server->session_key.response) {
-				mutex_unlock(&ses->server->srv_mutex);
+			if (!server->session_key.response) {
+				mutex_unlock(&server->srv_mutex);
 				return -ENOMEM;
 			}
-			ses->server->session_key.len =
+			server->session_key.len =
 						ses->auth_key.len;
 		}
-		ses->server->sequence_number = 0x2;
-		ses->server->session_estab = true;
+		server->sequence_number = 0x2;
+		server->session_estab = true;
 	}
-	mutex_unlock(&ses->server->srv_mutex);
+	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "CIFS session established successfully\n");
-	if (ses->binding)
-		cifs_chan_clear_need_reconnect(ses, ses->binding_chan->server);
-	else
-		cifs_chan_clear_need_reconnect(ses, ses->server);
+	spin_lock(&ses->chan_lock);
+	cifs_chan_clear_need_reconnect(ses, server);
+	spin_unlock(&ses->chan_lock);
 
-	/* keep existing ses state if binding */
+	/* Even if one channel is active, session is in good state */
 	spin_lock(&GlobalMid_Lock);
-	if (!ses->binding)
-		ses->status = CifsGood;
+	ses->status = CifsGood;
 	spin_unlock(&GlobalMid_Lock);
 
 	return 0;
@@ -1099,6 +1084,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data)
 	SESSION_SETUP_ANDX *pSMB;
 	char *bcc_ptr;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	__u16 bytes_remaining;
 
@@ -1110,7 +1096,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data)
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	bcc_ptr = sess_data->iov[2].iov_base;
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 
 	pSMB->req_no_secext.Capabilities = cpu_to_le32(capabilities);
 
@@ -1208,6 +1194,7 @@ sess_auth_kerberos(struct sess_data *sess_data)
 	SESSION_SETUP_ANDX *pSMB;
 	char *bcc_ptr;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	__u16 bytes_remaining;
 	struct key *spnego_key = NULL;
@@ -1222,9 +1209,9 @@ sess_auth_kerberos(struct sess_data *sess_data)
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	bcc_ptr = sess_data->iov[2].iov_base;
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 
-	spnego_key = cifs_get_spnego_key(ses);
+	spnego_key = cifs_get_spnego_key(ses, server);
 	if (IS_ERR(spnego_key)) {
 		rc = PTR_ERR(spnego_key);
 		spnego_key = NULL;
@@ -1348,12 +1335,13 @@ _sess_auth_rawntlmssp_assemble_req(struct sess_data *sess_data)
 {
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	char *bcc_ptr;
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 	if ((pSMB->req.hdr.Flags2 & SMBFLG2_UNICODE) == 0) {
 		cifs_dbg(VFS, "NTLMSSP requires Unicode support\n");
 		return -ENOSYS;
@@ -1387,6 +1375,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
 	struct smb_hdr *smb_buf;
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u16 bytes_remaining;
 	char *bcc_ptr;
 	unsigned char *ntlmsspblob = NULL;
@@ -1414,7 +1403,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
 
 	/* Build security blob before we assemble the request */
 	rc = build_ntlmssp_negotiate_blob(&ntlmsspblob,
-				     &blob_len, ses,
+				     &blob_len, ses, server,
 				     sess_data->nls_cp);
 	if (rc)
 		goto out;
@@ -1489,6 +1478,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
 	struct smb_hdr *smb_buf;
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u16 bytes_remaining;
 	char *bcc_ptr;
 	unsigned char *ntlmsspblob = NULL;
@@ -1505,7 +1495,8 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	smb_buf = (struct smb_hdr *)pSMB;
 	rc = build_ntlmssp_auth_blob(&ntlmsspblob,
-					&blob_len, ses, sess_data->nls_cp);
+					&blob_len, ses, server,
+					sess_data->nls_cp);
 	if (rc)
 		goto out_free_ntlmsspblob;
 	sess_data->iov[1].iov_len = blob_len;
@@ -1589,11 +1580,13 @@ out:
 	sess_data->result = rc;
 }
 
-static int select_sec(struct cifs_ses *ses, struct sess_data *sess_data)
+static int select_sec(struct sess_data *sess_data)
 {
 	int type;
+	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 
-	type = cifs_select_sectype(ses->server, ses->sectype);
+	type = cifs_select_sectype(server, ses->sectype);
 	cifs_dbg(FYI, "sess setup type %d\n", type);
 	if (type == Unspecified) {
 		cifs_dbg(VFS, "Unable to select appropriate authentication method!\n");
@@ -1624,7 +1617,8 @@ static int select_sec(struct cifs_ses *ses, struct sess_data *sess_data)
 }
 
 int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
-		    const struct nls_table *nls_cp)
+		   struct TCP_Server_Info *server,
+		   const struct nls_table *nls_cp)
 {
 	int rc = 0;
 	struct sess_data *sess_data;
@@ -1638,15 +1632,16 @@ int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
 	if (!sess_data)
 		return -ENOMEM;
 
-	rc = select_sec(ses, sess_data);
-	if (rc)
-		goto out;
-
 	sess_data->xid = xid;
 	sess_data->ses = ses;
+	sess_data->server = server;
 	sess_data->buf0_type = CIFS_NO_BUFFER;
 	sess_data->nls_cp = (struct nls_table *) nls_cp;
 
+	rc = select_sec(sess_data);
+	if (rc)
+		goto out;
+
 	while (sess_data->func)
 		sess_data->func(sess_data);