cifs: take cifs_tcp_ses_lock for status checks

While checking/updating status for tcp ses, smb ses or tcon,
we take GlobalMid_Lock. This doesn't make any sense.
Replaced it with cifs_tcp_ses_lock.

Ideally, we should take a spin lock per struct.
But since tcp ses, smb ses and tcon objects won't add up to a lot,
I think there should not be too much contention.

Also, in few other places, these are checked without locking.
Added locking for these.

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

Author: sprasad-microsoft

fs/cifs/cifs_swn.c

@@ -498,10 +498,10 @@ static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *a
 		goto unlock;
 	}
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->ses->server->tcpStatus != CifsExiting)
 		tcon->ses->server->tcpStatus = CifsNeedReconnect;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 unlock:
 	mutex_unlock(&tcon->ses->server->srv_mutex);

fs/cifs/cifsencrypt.c

@@ -141,9 +141,13 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
-	    server->tcpStatus == CifsNeedNegotiate)
+	    server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return rc;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if (!server->session_estab) {
 		memcpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);

fs/cifs/cifsglob.h

@@ -586,7 +586,7 @@ struct TCP_Server_Info {
 	char server_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
 	struct smb_version_operations	*ops;
 	struct smb_version_values	*vals;
-	/* updates to tcpStatus protected by GlobalMid_Lock */
+	/* updates to tcpStatus protected by cifs_tcp_ses_lock */
 	enum statusEnum tcpStatus; /* what we think the status is */
 	char *hostname; /* hostname portion of UNC string */
 	struct socket *ssocket;
@@ -924,7 +924,7 @@ struct cifs_ses {
 	struct mutex session_mutex;
 	struct TCP_Server_Info *server;	/* pointer to server info */
 	int ses_count;		/* reference counter */
-	enum statusEnum status;  /* updates protected by GlobalMid_Lock */
+	enum statusEnum status;  /* updates protected by cifs_tcp_ses_lock */
 	unsigned overrideSecFlg;  /* if non-zero override global sec flags */
 	char *serverOS;		/* name of operating system underlying server */
 	char *serverNOS;	/* name of network operating system of server */

fs/cifs/cifssmb.c

@@ -120,15 +120,18 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * only tree disconnect, open, and write, (and ulogoff which does not
 	 * have tcon) are allowed as we start force umount
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->tidStatus == CifsExiting) {
 		if (smb_command != SMB_COM_WRITE_ANDX &&
 		    smb_command != SMB_COM_OPEN_ANDX &&
 		    smb_command != SMB_COM_TREE_DISCONNECT) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb_command);
 			return -ENODEV;
 		}
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	retries = server->nr_targets;
 
@@ -148,8 +151,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		}
 
 		/* are we still trying to reconnect? */
-		if (server->tcpStatus != CifsNeedReconnect)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			break;
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (retries && --retries)
 			continue;
@@ -186,11 +193,14 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		rc = -EHOSTDOWN;
 		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously

fs/cifs/connect.c

@@ -467,9 +467,12 @@ reconnect_dfs_server(struct TCP_Server_Info *server,
 	dfs_cache_free_tgts(&tl);
 
 	/* Need to set up echo worker again once connection has been established */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate)
 		mod_delayed_work(cifsiod_wq, &server->echo, 0);
 
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	wake_up(&server->response_q);
 	return rc;
 }
@@ -571,15 +574,18 @@ server_unresponsive(struct TCP_Server_Info *server)
 	 * 65s kernel_recvmsg times out, and we see that we haven't gotten
 	 *     a response in >60s.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((server->tcpStatus == CifsGood ||
 	    server->tcpStatus == CifsNeedNegotiate) &&
 	    (!server->ops->can_echo || server->ops->can_echo(server)) &&
 	    time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
 			 (3 * server->echo_interval) / HZ);
 		cifs_reconnect(server, false);
 		return true;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return false;
 }
@@ -624,13 +630,18 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 		else
 			length = sock_recvmsg(server->ssocket, smb_msg, 0);
 
-		if (server->tcpStatus == CifsExiting)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus == CifsExiting) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -ESHUTDOWN;
+		}
 
 		if (server->tcpStatus == CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_reconnect(server, false);
 			return -ECONNABORTED;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (length == -ERESTARTSYS ||
 		    length == -EAGAIN ||
@@ -808,9 +819,9 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
 	cancel_delayed_work_sync(&server->echo);
 	cancel_delayed_work_sync(&server->resolve);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 	wake_up_all(&server->response_q);
 
 	/* check if we have blocked requests that need to free */
@@ -1427,9 +1438,9 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 	else
 		cancel_delayed_work_sync(&server->reconnect);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_crypto_secmech_release(server);
 
@@ -1582,7 +1593,9 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
 	 * to the struct since the kernel thread not created yet
 	 * no need to spinlock this update of tcpStatus
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	tcp_ses->tcpStatus = CifsNeedNegotiate;
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if ((ctx->max_credits < 20) || (ctx->max_credits > 60000))
 		tcp_ses->max_credits = SMB2_MAX_CREDITS_AVAILABLE;
@@ -1799,15 +1812,13 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* ses_count can never go negative */
 	WARN_ON(ses->ses_count < 0);
 
-	spin_lock(&GlobalMid_Lock);
 	if (ses->status == CifsGood)
 		ses->status = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_free_ipc(ses);
 
@@ -3075,12 +3086,15 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 		 * for just this mount.
 		 */
 		reset_cifs_unix_caps(xid, tcon, cifs_sb, ctx);
+		spin_lock(&cifs_tcp_ses_lock);
 		if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
 		    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
 		     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			rc = -EACCES;
 			goto out;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 	} else
 		tcon->unix_ext = 0; /* server does not support them */
 
@@ -3755,7 +3769,9 @@ CIFSTCon(const unsigned int xid, struct cifs_ses *ses,
 	if (rc == 0) {
 		bool is_unicode;
 
+		spin_lock(&cifs_tcp_ses_lock);
 		tcon->tidStatus = CifsGood;
+		spin_unlock(&cifs_tcp_ses_lock);
 		tcon->need_reconnect = false;
 		tcon->tid = smb_buffer_response->Tid;
 		bcc_ptr = pByteArea(smb_buffer_response);
@@ -3859,12 +3875,12 @@ cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,
 
 	rc = server->ops->negotiate(xid, ses, server);
 	if (rc == 0) {
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (server->tcpStatus == CifsNeedNegotiate)
 			server->tcpStatus = CifsGood;
 		else
 			rc = -EHOSTDOWN;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 
 	return rc;

fs/cifs/netmisc.c

@@ -896,10 +896,10 @@ map_and_check_smb_error(struct mid_q_entry *mid, bool logErr)
 		if (class == ERRSRV && code == ERRbaduid) {
 			cifs_dbg(FYI, "Server returned 0x%x, reconnecting session...\n",
 				code);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (mid->server->tcpStatus != CifsExiting)
 				mid->server->tcpStatus = CifsNeedReconnect;
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&cifs_tcp_ses_lock);
 		}
 	}
 

fs/cifs/sess.c

@@ -369,10 +369,10 @@ void cifs_ses_mark_for_reconnect(struct cifs_ses *ses)
 	int i;
 
 	for (i = 0; i < ses->chan_count; i++) {
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (ses->chans[i].server->tcpStatus != CifsExiting)
 			ses->chans[i].server->tcpStatus = CifsNeedReconnect;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 }
 
@@ -1052,9 +1052,9 @@ sess_establish_session(struct sess_data *sess_data)
 	spin_unlock(&ses->chan_lock);
 
 	/* Even if one channel is active, session is in good state */
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	ses->status = CifsGood;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return 0;
 }

fs/cifs/smb1ops.c

@@ -163,7 +163,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 {
 	__u64 mid = 0;
 	__u16 last_mid, cur_mid;
-	bool collision;
+	bool collision, reconnect;
 
 	spin_lock(&GlobalMid_Lock);
 
@@ -215,7 +215,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		 * an eventual reconnect to clean out the pending_mid_q.
 		 */
 		if (num_mids > 32768)
-			server->tcpStatus = CifsNeedReconnect;
+			reconnect = true;
 
 		if (!collision) {
 			mid = (__u64)cur_mid;
@@ -225,6 +225,13 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		cur_mid++;
 	}
 	spin_unlock(&GlobalMid_Lock);
+
+	if (reconnect) {
+		spin_lock(&cifs_tcp_ses_lock);
+		server->tcpStatus = CifsNeedReconnect;
+		spin_unlock(&cifs_tcp_ses_lock);
+	}
+
 	return mid;
 }
 

fs/cifs/smb2ops.c

@@ -121,9 +121,13 @@ smb2_add_credits(struct TCP_Server_Info *server,
 			 optype, scredits, add);
 	}
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect
-	    || server->tcpStatus == CifsExiting)
+	    || server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	switch (rc) {
 	case -1:
@@ -208,11 +212,15 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 				return rc;
 			spin_lock(&server->req_lock);
 		} else {
+			spin_unlock(&server->req_lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&server->req_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				return -ENOENT;
 			}
+			spin_unlock(&cifs_tcp_ses_lock);
 
+			spin_lock(&server->req_lock);
 			scredits = server->credits;
 			/* can deadlock with reopen */
 			if (scredits <= 8) {
@@ -4983,17 +4991,20 @@ static void smb2_decrypt_offload(struct work_struct *work)
 
 			mid->callback(mid);
 		} else {
+			spin_lock(&cifs_tcp_ses_lock);
 			spin_lock(&GlobalMid_Lock);
 			if (dw->server->tcpStatus == CifsNeedReconnect) {
 				mid->mid_state = MID_RETRY_NEEDED;
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				mid->callback(mid);
 			} else {
 				mid->mid_state = MID_REQUEST_SUBMITTED;
 				mid->mid_flags &= ~(MID_DELETED);
 				list_add_tail(&mid->qhead,
 					&dw->server->pending_mid_q);
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 			}
 		}
 		cifs_mid_q_entry_release(mid);