[Cluster-devel] cluster/gfs-kernel/src/gfs ops_inode.c

[bmarzins at sourceware.org]

CVSROOT:	/cvs/cluster
Module name:	cluster
Changes by:	bmarzins at sourceware.org	2006-10-23 20:47:23

Modified files:
	gfs-kernel/src/gfs: ops_inode.c 

Log message:
	Really gross hack!!!
	This is a workaround for one of the bugs the got lumped into 166701. It
	breaks POSIX behavior in a corner case to avoid crashing... It's icky.
	
	when NFS opens a file with O_CREAT, the kernel nfs daemon checks to see
	if the file exists. If it does, nfsd does the *right thing* (either opens the
	file, or if the file was opened with O_EXCL, returns an error).  If the file
	doesn't exist, it passes the request down to the underlying file system.
	Unfortunately, since nfs *knows* that the file doesn't exist, it doesn't
	bother to pass a nameidata structure, which would include the intent
	information. However since gfs is a cluster file system, the file could have
	been created on another node after nfs checks for it. If this is the case,
	gfs needs the intent information to do the *right thing*.  It panics when
	it finds a NULL pointer, instead of the nameidata. Now, instead of panicing,
	if gfs finds a NULL nameidata pointer. It assumes that the file was not
	created with O_EXCL.
	
	This assumption could be wrong, with the result that an application could
	thing that it has created a new file, when in fact, it has opened an existing
	one.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/cluster/gfs-kernel/src/gfs/ops_inode.c.diff?cvsroot=cluster&r1=1.14&r2=1.15

--- cluster/gfs-kernel/src/gfs/ops_inode.c	2006/10/15 07:25:09	1.14
+++ cluster/gfs-kernel/src/gfs/ops_inode.c	2006/10/23 20:47:23	1.15
@@ -118,7 +118,7 @@
 		if (!error)
 			break;
 		else if (error != -EEXIST ||
-			 (nd->intent.open.flags & O_EXCL)) {
+			 (nd && (nd->intent.open.flags & O_EXCL))) {
 			gfs_holder_uninit(&d_gh);
 			return error;
 		}