linux-kernel - Re: [patch 06/24] hpfs: dont call notify

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Date:	Fri, 9 May 2008 03:59:35 +0200 (CEST)
From:	Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
To:	Christoph Hellwig <hch@...radead.org>
cc:	Miklos Szeredi <miklos@...redi.hu>, akpm@...ux-foundation.org,
	viro@...IV.linux.org.uk, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 06/24] hpfs: dont call notify_change

On Thu, 8 May 2008, Christoph Hellwig wrote:

> On Tue, May 06, 2008 at 11:13:33AM +0200, Miklos Szeredi wrote:
> > From: Miklos Szeredi <mszeredi@...e.cz>
> > 
> > hpfs_unlink() calls notify_change() to truncate the file before
> > deleting.  Replace with explicit call to hpfs_notify_change().
> > 
> > This is equivalent, except that:
> >  - security_inode_setattr() is not called before hpfs_notify_change()
> >  - fsnotify_change() is not called after hpfs_notify_change()
> > 
> > The truncation is just an implementation detail, so both the security
> > check and the notification are unnecessary.
> > 
> > Possibly even the ctime modification is wrong?
> 
> This code is rahter scary, as we'd lost the content without the file
> when the second remove_dirent attempt fails.  Because of that we should
> at least keep the ctime change so an app can know the file was touched.

Unfortunatelly this is design bug in HPFS --- removing a dirent can 
allocate more space. There's nothing that can be done about it. OS/2 
crashes on panic when this situation is triggered :)

Mikulas

> Again, looks correct but I'm not convinced about all these changes.
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