Re: NFSD/gfs crashes with oops

[Bas van der Vlies <basv@sara.nl>]

Just for the recorde. The GFS guys have made a patch for the crash in 
CVS stable:

CVSROOT:	/cvs/cluster
Module name:	cluster
Branch: 	STABLE
Changes by:	bmarzins@sourceware.org	2006-03-08 20:47:09

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 _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.

-- 
--
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*                                                                  *
*  Bas van der Vlies                     e-mail: basv@sara.nl      *
*  SARA - Academic Computing Services    phone:  +31 20 592 8012   *
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