cifs: avoid use of global locks for high contention data

During analysis of multichannel perf, it was seen that
the global locks cifs_tcp_ses_lock and GlobalMid_Lock, which
were shared between various data structures were causing a
lot of contention points.

With this change, we're breaking down the use of these locks
by introducing new locks at more granular levels. i.e.
server->srv_lock, ses->ses_lock and tcon->tc_lock to protect
the unprotected fields of server, session and tcon structs;
and server->mid_lock to protect mid related lists and entries
at server level.

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

1 files changed, 12 insertions, 12 deletions

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 295ee8b88055..131bec79d6fd 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -162,7 +162,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (smb2_command == SMB2_TREE_CONNECT || smb2_command == SMB2_IOCTL)
 		return 0;
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&tcon->tc_lock);
 	if (tcon->status == TID_EXITING) {
 		/*
 		 * only tree disconnect, open, and write,
@@ -172,13 +172,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		if ((smb2_command != SMB2_WRITE) &&
 		   (smb2_command != SMB2_CREATE) &&
 		   (smb2_command != SMB2_TREE_DISCONNECT)) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&tcon->tc_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb2_command);
 			return -ENODEV;
 		}
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&tcon->tc_lock);
 	if ((!tcon->ses) || (tcon->ses->ses_status == SES_EXITING) ||
 	    (!tcon->ses->server) || !server)
 		return -EIO;
@@ -217,12 +217,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		}
 
 		/* are we still trying to reconnect? */
-		spin_lock(&cifs_tcp_ses_lock);
+		spin_lock(&server->srv_lock);
 		if (server->tcpStatus != CifsNeedReconnect) {
-			spin_unlock(&cifs_tcp_ses_lock);
+			spin_unlock(&server->srv_lock);
 			break;
 		}
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 
 		if (retries && --retries)
 			continue;
@@ -256,13 +256,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		rc = -EHOSTDOWN;
 		goto out;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	/*
 	 * need to prevent multiple threads trying to simultaneously
@@ -3911,15 +3911,15 @@ SMB2_echo(struct TCP_Server_Info *server)
 
 	cifs_dbg(FYI, "In echo request for conn_id %lld\n", server->conn_id);
 
-	spin_lock(&cifs_tcp_ses_lock);
+	spin_lock(&server->srv_lock);
 	if (server->ops->need_neg &&
 	    server->ops->need_neg(server)) {
-		spin_unlock(&cifs_tcp_ses_lock);
+		spin_unlock(&server->srv_lock);
 		/* No need to send echo on newly established connections */
 		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 		return rc;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&server->srv_lock);
 
 	rc = smb2_plain_req_init(SMB2_ECHO, NULL, server,
 				 (void **)&req, &total_len);