[CIFS] Fix byte range locking to Windows when Windows server returns

illegal RFC1001 length (which had caused the lock to block forever
until killed).

fs/cifs/CHANGES

+Version 1.38
+------------
+Fix tcp socket retransmission timeouts (e.g. on ENOSPACE from the socket)
+to be smaller at first (but increasing) so large write performance performance
+over GigE is better.  Do not hang thread on illegal byte range lock response
+from Windows (Windows can send an RFC1001 size which does not match smb size) by
+allowing an SMBs TCP length to be up to a few bytes longer than it should be.
+wsize and rsize can now be larger than negotiated buffer size if server
+supports large readx/writex, even when directio mount flag not specified.
+Write size will in many cases now be 16K instead of 4K which greatly helps
+file copy performance on lightly loaded networks.
+
 Version 1.37
 ------------
 Fix readdir caching when unlink removes file in current search buffer,

fs/cifs/README

@@ -294,8 +294,8 @@ A partial list of the supported mount options follows:
 		during the local client kernel build will be used.
 		If server does not support Unicode, this parameter is
 		unused.
-  rsize		default read size
-  wsize		default write size
+  rsize		default read size (usually 16K)
+  wsize		default write size (usually 16K, 32K is often better over GigE)
   rw		mount the network share read-write (note that the
 		server may still consider the share read-only)
   ro		mount network share read-only

fs/cifs/TODO

-version 1.36 September 6, 2005
+version 1.37 October 9, 2005
 
 A Partial List of Missing Features
 ==================================
@@ -38,8 +38,8 @@ by unlocking all known byte range locks that we locked on the file.
 i) quota support (needs minor kernel change since quota calls
 to make it to network filesystems or deviceless filesystems)
 
-j) finish writepages support (multi-page write behind for improved
-performance) and syncpage. Started by Shaggy.
+j) investigate sync behavior (including syncpage) and check  
+for proper behavior of intr/nointr
 
 k) hook lower into the sockets api (as NFS/SunRPC does) to avoid the
 extra copy in/out of the socket buffers in some cases.

fs/cifs/misc.c

@@ -420,6 +420,7 @@ int
 checkSMB(struct smb_hdr *smb, __u16 mid, int length)
 {
 	__u32 len = smb->smb_buf_length;
+	__u32 clc_len;  /* calculated length */
 	cFYI(0,
 	     ("Entering checkSMB with Length: %x, smb_buf_length: %x ",
 	      length, len));
@@ -440,19 +441,26 @@ checkSMB(struct smb_hdr *smb, __u16 mid, int length)
 			cERROR(1,
 			       ("smb_buf_length greater than MaxBufSize"));
 		cERROR(1,
-		       ("bad smb detected. Illegal length. The mid=%d",
+		       ("bad smb detected. Illegal length. mid=%d",
 			smb->Mid));
 		return 1;
 	}
 
 	if (checkSMBhdr(smb, mid))
 		return 1;
-
-	if ((4 + len != smbCalcSize_LE(smb))
+	clc_len = smbCalcSize_LE(smb);
+	if ((4 + len != clc_len)
 	    || (4 + len != (unsigned int)length)) {
-		cERROR(1, ("smbCalcSize %x ", smbCalcSize_LE(smb)));
-		cERROR(1,
-		       ("bad smb size detected. The Mid=%d", smb->Mid));
+		cERROR(1, ("Calculated size 0x%x vs actual length 0x%x",
+				clc_len, 4 + len));
+		cERROR(1, ("bad smb size detected for Mid=%d", smb->Mid));
+		/* Windows XP can return a few bytes too much, presumably
+		an illegal pad, at the end of byte range lock responses 
+		so we allow for up to eight byte pad, as long as actual
+		received length is as long or longer than calculated length */
+		if((4+len > clc_len) && (len <= clc_len + 3))
+			return 0;
+		else
 			return 1;
 	}
 	return 0;