releases/2.6.27.8/cifs-reduce-number-of-socket-retries-in-large-write-path.patch

From sjayaraman@suse.de  Wed Dec  3 08:51:11 2008
From: Steve French <sfrench@us.ibm.com>
Date: Fri, 21 Nov 2008 12:58:40 +0530
Subject: cifs: Reduce number of socket retries in large write path
To: stable@kernel.org
Cc: Steve French <smfrench@gmail.com>, Jeff Layton <jlayton@redhat.com>, Shirish S Pargaonkar <shirishp@us.ibm.com>
Message-ID: <49266328.4000409@suse.de>

From: Steve French <sfrench@us.ibm.com>

Backport of upstream commit edf1ae403896cb7750800508b14996ba6be39a53
for -stable.

[CIFS] Reduce number of socket retries in large write path

CIFS in some heavy stress conditions cifs could get EAGAIN
repeatedly in smb_send2 which led to repeated retries and eventually
failure of large writes which could lead to data corruption.

There are three changes that were suggested by various network
developers:

1) convert cifs from non-blocking to blocking tcp sendmsg
(we left in the retry on failure)
2) change cifs to not set sendbuf and rcvbuf size for the socket
(let tcp autotune the buffer sizes since that works much better
in the TCP stack now)
3) if we have a partial frame sent in smb_send2, mark the tcp
session as invalid (close the socket and reconnect) so we do
not corrupt the remaining part of the SMB with the beginning
of the next SMB.

This does not appear to hurt performance measurably and has
been run in various scenarios, but it definately removes
a corruption that we were seeing in some high stress
test cases.

Acked-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 fs/cifs/cifsglob.h  |    2 +
 fs/cifs/cifsproto.h |    2 -
 fs/cifs/connect.c   |   58 ++++++++++++++++++++++++++++++++++++++--------------
 fs/cifs/transport.c |   41 +++++++++++++++++++++++++++---------
 4 files changed, 77 insertions(+), 26 deletions(-)

--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -141,6 +141,8 @@ struct TCP_Server_Info {
 	char versionMajor;
 	char versionMinor;
 	bool svlocal:1;			/* local server or remote */
+	bool noblocksnd;		/* use blocking sendmsg */
+	bool noautotune;		/* do not autotune send buf sizes */
 	atomic_t socketUseCount; /* number of open cifs sessions on socket */
 	atomic_t inFlight;  /* number of requests on the wire to server */
 #ifdef CONFIG_CIFS_STATS2
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -36,7 +36,7 @@ extern void cifs_buf_release(void *);
 extern struct smb_hdr *cifs_small_buf_get(void);
 extern void cifs_small_buf_release(void *);
 extern int smb_send(struct socket *, struct smb_hdr *,
-			unsigned int /* length */ , struct sockaddr *);
+			unsigned int /* length */ , struct sockaddr *, bool);
 extern unsigned int _GetXid(void);
 extern void _FreeXid(unsigned int);
 #define GetXid() (int)_GetXid(); cFYI(1,("CIFS VFS: in %s as Xid: %d with uid: %d",__func__, xid,current->fsuid));
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -90,6 +90,8 @@ struct smb_vol {
 	bool nocase:1;     /* request case insensitive filenames */
 	bool nobrl:1;      /* disable sending byte range locks to srv */
 	bool seal:1;       /* request transport encryption on share */
+	bool noblocksnd:1;
+	bool noautotune:1;
 	unsigned int rsize;
 	unsigned int wsize;
 	unsigned int sockopt;
@@ -100,9 +102,11 @@ struct smb_vol {
 static int ipv4_connect(struct sockaddr_in *psin_server,
 			struct socket **csocket,
 			char *netb_name,
-			char *server_netb_name);
+			char *server_netb_name,
+			bool noblocksnd,
+			bool nosndbuf); /* ipv6 never set sndbuf size */
 static int ipv6_connect(struct sockaddr_in6 *psin_server,
-			struct socket **csocket);
+			struct socket **csocket, bool noblocksnd);
 
 
 	/*
@@ -188,12 +192,13 @@ cifs_reconnect(struct TCP_Server_Info *s
 		try_to_freeze();
 		if (server->protocolType == IPV6) {
 			rc = ipv6_connect(&server->addr.sockAddr6,
-					  &server->ssocket);
+					  &server->ssocket, server->noautotune);
 		} else {
 			rc = ipv4_connect(&server->addr.sockAddr,
 					&server->ssocket,
 					server->workstation_RFC1001_name,
-					server->server_RFC1001_name);
+					server->server_RFC1001_name,
+					server->noblocksnd, server->noautotune);
 		}
 		if (rc) {
 			cFYI(1, ("reconnect error %d", rc));
@@ -409,8 +414,14 @@ incomplete_rcv:
 			msleep(1); /* minimum sleep to prevent looping
 				allowing socket to clear and app threads to set
 				tcpStatus CifsNeedReconnect if server hung */
-			if (pdu_length < 4)
+			if (pdu_length < 4) {
+				iov.iov_base = (4 - pdu_length) +
+						(char *)smb_buffer;
+				iov.iov_len = pdu_length;
+				smb_msg.msg_control = NULL;
+				smb_msg.msg_controllen = 0;
 				goto incomplete_rcv;
+			}
 			else
 				continue;
 		} else if (length <= 0) {
@@ -1186,6 +1197,10 @@ cifs_parse_mount_options(char *options, 
 			/* ignore */
 		} else if (strnicmp(data, "rw", 2) == 0) {
 			vol->rw = true;
+		} else if (strnicmp(data, "noblocksnd", 11) == 0) {
+			vol->noblocksnd = true;
+		} else if (strnicmp(data, "noautotune", 10) == 0) {
+			vol->noautotune = true;
 		} else if ((strnicmp(data, "suid", 4) == 0) ||
 				   (strnicmp(data, "nosuid", 6) == 0) ||
 				   (strnicmp(data, "exec", 4) == 0) ||
@@ -1506,7 +1521,8 @@ static void rfc1002mangle(char *target, 
 
 static int
 ipv4_connect(struct sockaddr_in *psin_server, struct socket **csocket,
-	     char *netbios_name, char *target_name)
+		char *netbios_name, char *target_name,
+		bool noblocksnd, bool noautotune)
 {
 	int rc = 0;
 	int connected = 0;
@@ -1578,11 +1594,15 @@ ipv4_connect(struct sockaddr_in *psin_se
 		 (*csocket)->sk->sk_sndbuf,
 		 (*csocket)->sk->sk_rcvbuf, (*csocket)->sk->sk_rcvtimeo));
 	(*csocket)->sk->sk_rcvtimeo = 7 * HZ;
+	if (!noblocksnd)
+		(*csocket)->sk->sk_sndtimeo = 3 * HZ;
 	/* make the bufsizes depend on wsize/rsize and max requests */
-	if ((*csocket)->sk->sk_sndbuf < (200 * 1024))
-		(*csocket)->sk->sk_sndbuf = 200 * 1024;
-	if ((*csocket)->sk->sk_rcvbuf < (140 * 1024))
-		(*csocket)->sk->sk_rcvbuf = 140 * 1024;
+	if (noautotune) {
+		if ((*csocket)->sk->sk_sndbuf < (200 * 1024))
+			(*csocket)->sk->sk_sndbuf = 200 * 1024;
+		if ((*csocket)->sk->sk_rcvbuf < (140 * 1024))
+			(*csocket)->sk->sk_rcvbuf = 140 * 1024;
+	}
 
 	/* send RFC1001 sessinit */
 	if (psin_server->sin_port == htons(RFC1001_PORT)) {
@@ -1619,7 +1639,7 @@ ipv4_connect(struct sockaddr_in *psin_se
 			/* sizeof RFC1002_SESSION_REQUEST with no scope */
 			smb_buf->smb_buf_length = 0x81000044;
 			rc = smb_send(*csocket, smb_buf, 0x44,
-				(struct sockaddr *)psin_server);
+				(struct sockaddr *)psin_server, noblocksnd);
 			kfree(ses_init_buf);
 			msleep(1); /* RFC1001 layer in at least one server
 				      requires very short break before negprot
@@ -1639,7 +1659,8 @@ ipv4_connect(struct sockaddr_in *psin_se
 }
 
 static int
-ipv6_connect(struct sockaddr_in6 *psin_server, struct socket **csocket)
+ipv6_connect(struct sockaddr_in6 *psin_server, struct socket **csocket,
+		bool noblocksnd)
 {
 	int rc = 0;
 	int connected = 0;
@@ -1708,6 +1729,8 @@ ipv6_connect(struct sockaddr_in6 *psin_s
 		the default. sock_setsockopt not used because it expects
 		user space buffer */
 	(*csocket)->sk->sk_rcvtimeo = 7 * HZ;
+	if (!noblocksnd)
+		(*csocket)->sk->sk_sndtimeo = 3 * HZ;
 
 	return rc;
 }
@@ -1961,11 +1984,14 @@ cifs_mount(struct super_block *sb, struc
 			cFYI(1, ("attempting ipv6 connect"));
 			/* BB should we allow ipv6 on port 139? */
 			/* other OS never observed in Wild doing 139 with v6 */
-			rc = ipv6_connect(&sin_server6, &csocket);
+			rc = ipv6_connect(&sin_server6, &csocket,
+					volume_info.noblocksnd);
 		} else
 			rc = ipv4_connect(&sin_server, &csocket,
-				  volume_info.source_rfc1001_name,
-				  volume_info.target_rfc1001_name);
+					volume_info.source_rfc1001_name,
+					volume_info.target_rfc1001_name,
+					volume_info.noblocksnd,
+					volume_info.noautotune);
 		if (rc < 0) {
 			cERROR(1, ("Error connecting to IPv4 socket. "
 				   "Aborting operation"));
@@ -1980,6 +2006,8 @@ cifs_mount(struct super_block *sb, struc
 			sock_release(csocket);
 			goto out;
 		} else {
+			srvTcp->noblocksnd = volume_info.noblocksnd;
+			srvTcp->noautotune = volume_info.noautotune;
 			memcpy(&srvTcp->addr.sockAddr, &sin_server,
 				sizeof(struct sockaddr_in));
 			atomic_set(&srvTcp->inFlight, 0);
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -162,7 +162,7 @@ void DeleteTconOplockQEntries(struct cif
 
 int
 smb_send(struct socket *ssocket, struct smb_hdr *smb_buffer,
-	 unsigned int smb_buf_length, struct sockaddr *sin)
+	 unsigned int smb_buf_length, struct sockaddr *sin, bool noblocksnd)
 {
 	int rc = 0;
 	int i = 0;
@@ -179,7 +179,10 @@ smb_send(struct socket *ssocket, struct 
 	smb_msg.msg_namelen = sizeof(struct sockaddr);
 	smb_msg.msg_control = NULL;
 	smb_msg.msg_controllen = 0;
-	smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL; /* BB add more flags?*/
+	if (noblocksnd)
+		smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
+	else
+		smb_msg.msg_flags = MSG_NOSIGNAL;
 
 	/* smb header is converted in header_assemble. bcc and rest of SMB word
 	   area, and byte area if necessary, is converted to littleendian in
@@ -230,8 +233,8 @@ smb_send(struct socket *ssocket, struct 
 }
 
 static int
-smb_send2(struct socket *ssocket, struct kvec *iov, int n_vec,
-	  struct sockaddr *sin)
+smb_send2(struct TCP_Server_Info *server, struct kvec *iov, int n_vec,
+	  struct sockaddr *sin, bool noblocksnd)
 {
 	int rc = 0;
 	int i = 0;
@@ -241,6 +244,7 @@ smb_send2(struct socket *ssocket, struct
 	unsigned int total_len;
 	int first_vec = 0;
 	unsigned int smb_buf_length = smb_buffer->smb_buf_length;
+	struct socket *ssocket = server->ssocket;
 
 	if (ssocket == NULL)
 		return -ENOTSOCK; /* BB eventually add reconnect code here */
@@ -249,7 +253,10 @@ smb_send2(struct socket *ssocket, struct
 	smb_msg.msg_namelen = sizeof(struct sockaddr);
 	smb_msg.msg_control = NULL;
 	smb_msg.msg_controllen = 0;
-	smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL; /* BB add more flags?*/
+	if (noblocksnd)
+		smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
+	else
+		smb_msg.msg_flags = MSG_NOSIGNAL;
 
 	/* smb header is converted in header_assemble. bcc and rest of SMB word
 	   area, and byte area if necessary, is converted to littleendian in
@@ -313,6 +320,16 @@ smb_send2(struct socket *ssocket, struct
 		i = 0; /* in case we get ENOSPC on the next send */
 	}
 
+	if ((total_len > 0) && (total_len != smb_buf_length + 4)) {
+		cFYI(1, ("partial send (%d remaining), terminating session",
+				total_len));
+		/* If we have only sent part of an SMB then the next SMB
+		   could be taken as the remainder of this one.  We need
+		   to kill the socket so the server throws away the partial
+		   SMB */
+		server->tcpStatus = CifsNeedReconnect;
+	}
+
 	if (rc < 0) {
 		cERROR(1, ("Error %d sending data on socket to server", rc));
 	} else
@@ -519,8 +536,9 @@ SendReceive2(const unsigned int xid, str
 #ifdef CONFIG_CIFS_STATS2
 	atomic_inc(&ses->server->inSend);
 #endif
-	rc = smb_send2(ses->server->ssocket, iov, n_vec,
-		      (struct sockaddr *) &(ses->server->addr.sockAddr));
+	rc = smb_send2(ses->server, iov, n_vec,
+			(struct sockaddr *) &(ses->server->addr.sockAddr),
+			ses->server->noblocksnd);
 #ifdef CONFIG_CIFS_STATS2
 	atomic_dec(&ses->server->inSend);
 	midQ->when_sent = jiffies;
@@ -712,7 +730,8 @@ SendReceive(const unsigned int xid, stru
 	atomic_inc(&ses->server->inSend);
 #endif
 	rc = smb_send(ses->server->ssocket, in_buf, in_buf->smb_buf_length,
-		      (struct sockaddr *) &(ses->server->addr.sockAddr));
+			(struct sockaddr *) &(ses->server->addr.sockAddr),
+			ses->server->noblocksnd);
 #ifdef CONFIG_CIFS_STATS2
 	atomic_dec(&ses->server->inSend);
 	midQ->when_sent = jiffies;
@@ -852,7 +871,8 @@ send_nt_cancel(struct cifsTconInfo *tcon
 		return rc;
 	}
 	rc = smb_send(ses->server->ssocket, in_buf, in_buf->smb_buf_length,
-	      (struct sockaddr *) &(ses->server->addr.sockAddr));
+		(struct sockaddr *) &(ses->server->addr.sockAddr),
+		ses->server->noblocksnd);
 	up(&ses->server->tcpSem);
 	return rc;
 }
@@ -942,7 +962,8 @@ SendReceiveBlockingLock(const unsigned i
 	atomic_inc(&ses->server->inSend);
 #endif
 	rc = smb_send(ses->server->ssocket, in_buf, in_buf->smb_buf_length,
-		      (struct sockaddr *) &(ses->server->addr.sockAddr));
+			(struct sockaddr *) &(ses->server->addr.sockAddr),
+			ses->server->noblocksnd);
 #ifdef CONFIG_CIFS_STATS2
 	atomic_dec(&ses->server->inSend);
 	midQ->when_sent = jiffies;