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Subject: Re: GFS2 and DLM
From: Steven Whitehouse <swhiteho@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Linus Torvalds <torvalds@osdl.org>, David Teigland <teigland@redhat.com>,
       Patrick Caulfield <pcaulfie@redhat.com>,
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Organization: Red Hat (UK) Ltd
Date: Fri, 23 Jun 2006 16:54:04 +0100
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Hi,

On Fri, 2006-06-23 at 15:54 +0100, Christoph Hellwig wrote:
> On Tue, Jun 20, 2006 at 01:17:13PM +0100, Steven Whitehouse wrote:
> > Hi,
> > 
> > Linus, Andrew suggested to me to send this pull request to you directly.
> > Please consider merging the GFS2 filesystem and DLM from (they are both
> > in the same tree for ease of testing):
> 
> What's going on with gfs2_repermission?  For one it's a totally useless
> wrapper.  Second we prefer to have everyone use vfs_permission or
> file_permission and third WTF is it doing anywhere?  Except for very rare
> cases checking permissions is the VFS's job.
> 

gfs2_repermission doesn't exist in the latest git tree. I had spotted
that one earlier and replaced it with direct calls to permission.
vfs_permission is just a wrapper for permission.

file_permission which you are advocating using has the comment:

/**
 * file_permission  -  check for additional access rights to a given file
 * @file:       file to check access rights for
 * @mask:       right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
 *
 * Used to check for read/write/execute permissions on an already opened
 * file.
 *
 * Note:
 *      Do not use this function in new code.  All access checks should
 *      be done using vfs_permission().
 */

so I guess thats not the right thing. I'm afraid I fail to see whats wrong
with just calling permission directly... we need to call it mainly because
the VFS only does locking within a single node and we recheck the permissions
in a few places after we've taken the glocks which provide cluster-wide
exclusion.

Steve.