[CIFS] Add writepages support to shrink memory usage on writes,

eliminate the double copy, and improve cifs write performance and
help the server by upping the typical write size from 4K to 16K
(or even larger if wsize set explicitly)  for servers which support this.
Part 1 of 2

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steve French  <sfrench@us.ibm.com>

1 files changed, 55 insertions, 40 deletions

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 9e8e85a8d186..38b3b2463ae4 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -147,16 +147,19 @@ smb_send(struct socket *ssocket, struct smb_hdr *smb_buffer,
 	   Flags2 is converted in SendReceive */
 
 	smb_buffer->smb_buf_length = cpu_to_be32(smb_buffer->smb_buf_length);
-	cFYI(1, ("Sending smb of length %d ", smb_buf_length));
+	cFYI(1, ("Sending smb of length %d", smb_buf_length));
 	dump_smb(smb_buffer, len);
 
 	while (len > 0) {
 		rc = kernel_sendmsg(ssocket, &smb_msg, &iov, 1, len);
 		if ((rc == -ENOSPC) || (rc == -EAGAIN)) {
 			i++;
-			if(i > 60) {
+		/* smaller timeout here than send2 since smaller size */
+		/* Although it may not be required, this also is smaller 
+		   oplock break time */  
+			if(i > 30) {
 				cERROR(1,
-				   ("sends on sock %p stuck for 30 seconds",
+				   ("sends on sock %p stuck for 15 seconds",
 				    ssocket));
 				rc = -EAGAIN;
 				break;
@@ -172,7 +175,7 @@ smb_send(struct socket *ssocket, struct smb_hdr *smb_buffer,
 	}
 
 	if (rc < 0) {
-		cERROR(1,("Error %d sending data on socket to server.", rc));
+		cERROR(1,("Error %d sending data on socket to server", rc));
 	} else {
 		rc = 0;
 	}
@@ -182,22 +185,20 @@ smb_send(struct socket *ssocket, struct smb_hdr *smb_buffer,
 
 #ifdef CONFIG_CIFS_EXPERIMENTAL
 static int
-smb_send2(struct socket *ssocket, struct smb_hdr *smb_buffer,
-	 unsigned int smb_hdr_length, const char * data, unsigned int datalen,
-	 struct sockaddr *sin)
+smb_send2(struct socket *ssocket, struct kvec *iov, int n_vec,
+	  struct sockaddr *sin)
 {
 	int rc = 0;
 	int i = 0;
 	struct msghdr smb_msg;
-	struct kvec iov[2];
-	unsigned len = smb_hdr_length + 4;
+	struct smb_hdr *smb_buffer = iov[0].iov_base;
+	unsigned int len = iov[0].iov_len;
+	unsigned int total_len;
+	int first_vec = 0;
 	
 	if(ssocket == NULL)
 		return -ENOTSOCK; /* BB eventually add reconnect code here */
-	iov[0].iov_base = smb_buffer;
-	iov[0].iov_len = len;
-	iov[1].iov_base = data;
-	iov[1].iov_len = datalen;
+
 	smb_msg.msg_name = sin;
 	smb_msg.msg_namelen = sizeof (struct sockaddr);
 	smb_msg.msg_control = NULL;
@@ -209,18 +210,23 @@ smb_send2(struct socket *ssocket, struct smb_hdr *smb_buffer,
 	   cifssmb.c and RFC1001 len is converted to bigendian in smb_send 
 	   Flags2 is converted in SendReceive */
 
+
+	total_len = 0;
+	for (i = 0; i < n_vec; i++)
+		total_len += iov[i].iov_len;
+
 	smb_buffer->smb_buf_length = cpu_to_be32(smb_buffer->smb_buf_length);
-	cFYI(1, ("Sending smb:  hdrlen %d datalen %d",
-		 smb_hdr_length,datalen));
+	cFYI(1, ("Sending smb:  total_len %d", total_len));
 	dump_smb(smb_buffer, len);
 
-	while (len + datalen > 0) {
-		rc = kernel_sendmsg(ssocket, &smb_msg, iov, 2, len);
+	while (total_len) {
+		rc = kernel_sendmsg(ssocket, &smb_msg, &iov[first_vec],
+				    n_vec - first_vec, total_len);
 		if ((rc == -ENOSPC) || (rc == -EAGAIN)) {
 			i++;
-			if(i > 60) {
+			if(i > 40) {
 				cERROR(1,
-				   ("sends on sock %p stuck for 30 seconds",
+				   ("sends on sock %p stuck for 20 seconds",
 				    ssocket));
 				rc = -EAGAIN;
 				break;
@@ -230,43 +236,52 @@ smb_send2(struct socket *ssocket, struct smb_hdr *smb_buffer,
 		}
 		if (rc < 0) 
 			break;
-		if(iov[0].iov_len > 0) {
-			if(rc >= len) {
-				iov[0].iov_len = 0;
-				rc -= len;
-				len = 0;
-			} else {  /* some of hdr was not sent */
-				len -= rc;
-				iov[0].iov_len -= rc;
-				iov[0].iov_base += rc;
-				continue;
-			}
+
+		if (rc >= total_len) {
+			WARN_ON(rc > total_len);
+			break;
+		}
+		if(rc == 0) {
+			/* should never happen, letting socket clear before
+			   retrying is our only obvious option here */
+			cERROR(1,("tcp sent no data");
+			msleep(500);
+			continue;
 		}
-		if((iov[0].iov_len == 0) && (rc > 0)){
-			iov[1].iov_base += rc;
-			iov[1].iov_len -= rc;
-			datalen -= rc;
+		total_len -= rc;
+		for (i = first_vec; i < n_vec; i++) {
+			if (iov[i].iov_len) {
+				if (rc > iov[i].iov_len) {
+					rc -= iov[i].iov_len;
+					iov[i].iov_len = 0;
+				} else {
+					iov[i].iov_base += rc;
+					iov[i].iov_len -= rc;
+					first_vec = i;
+					break;
+				}
+			}
 		}
 	}
 
 	if (rc < 0) {
-		cERROR(1,("Error %d sending data on socket to server.", rc));
-	} else {
+		cERROR(1,("Error %d sending data on socket to server", rc));
+	} else
 		rc = 0;
-	}
 
 	return rc;
 }
 
 int
 SendReceive2(const unsigned int xid, struct cifsSesInfo *ses, 
-	     struct smb_hdr *in_buf, int hdrlen, const char * data,
-	     int datalen, int *pbytes_returned, const int long_op)
+	     struct kvec *iov, int n_vec, int *pbytes_returned,
+	     const int long_op)
 {
 	int rc = 0;
 	unsigned int receive_len;
 	unsigned long timeout;
 	struct mid_q_entry *midQ;
+	struct smb_hdr *in_buf = iov[0].iov_base;
 
 	if (ses == NULL) {
 		cERROR(1,("Null smb session"));
@@ -364,7 +379,7 @@ SendReceive2(const unsigned int xid, struct cifsSesInfo *ses,
 /* 	rc = cifs_sign_smb2(in_buf, data, ses->server, &midQ->sequence_number); */
 
 	midQ->midState = MID_REQUEST_SUBMITTED;
-	rc = smb_send2(ses->server->ssocket, in_buf, hdrlen, data, datalen,
+	rc = smb_send2(ses->server->ssocket, iov, n_vec,
 		      (struct sockaddr *) &(ses->server->addr.sockAddr));
 	if(rc < 0) {
 		DeleteMidQEntry(midQ);