[PATCH] [CIFS] Fix for oops in fs/locks.c in 2.6.13-rc runningconnectathon byte range lock test over cifs

[Steve French]

[CIFS] Fix oops in fs/locks.c on close of file with pending locks

The recent change to locks_remove_flock code in fs/locks.c changes how 
byte range locks are removed from closing files, which shows up a bug in
cifs.   The assumption in the cifs code was that the close call sent to 
the server would remove any pending locks on the server on this file, 
but that is no longer safe as the fs/locks.c code on the client wants 
unlock of 0 to PATH_MAX to remove all locks (at least from this client, 
it is not possible AFAIK to remove all locks from other clients made to 
the server copy of the file).   Note that cifs locks are different from 
posix locks - and it is not possible to map posix locks perfectly on the
wire yet, due to restrictions of the cifs network protocol, even to 
Samba without adding a new request type to the network protocol (which 
we plan to do for Samba 3.0.21 within a few months), but the local 
client will have the correct, posix view, of the lock in most cases. 

The correct fix for cifs for this would involve a bigger change than I 
would like to do this late in the 2.6.13-rc cycle - and would involve 
cifs keeping track of all unmerged (uncoalesced) byte range locks for 
each remote inode and scanning that list to remove locks that intersect 
or fall wholly within the range - locks that intersect may have to be 
reaquired with the smaller, remaining range.

Signed-off-by: Steve French <sfrench@xxxxxxxxxx>
Signed-off-by: Dave Kleikamp <shaggy@xxxxxxxxxxxxxx>

diff -Naur linux-2.6.13-rc7/fs/cifs/file.c linux/fs/cifs/file.c
--- linux-2.6.13-rc7/fs/cifs/file.c	2005-06-17 14:48:29.000000000 -0500
+++ linux/fs/cifs/file.c	2005-08-26 07:40:37.000000000 -0500
@@ -643,7 +643,7 @@
 			 netfid, length,
 			 pfLock->fl_start, numUnlock, numLock, lockType,
 			 wait_flag);
-	if (rc == 0 && (pfLock->fl_flags & FL_POSIX))
+	if (pfLock->fl_flags & FL_POSIX)
 		posix_lock_file_wait(file, pfLock);
 	FreeXid(xid);
 	return rc;


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