linux-kernel - Re: [PATCH 5/5] libfs : file/directory removal fix, 2.6.18

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Message-ID: <20061123090116.GK3078@ftp.linux.org.uk>
Date:	Thu, 23 Nov 2006 09:01:16 +0000
From:	Al Viro <viro@....linux.org.uk>
To:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
Cc:	Greg KH <greg@...ah.com>, ltt-dev@...fik.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] libfs : file/directory removal fix, 2.6.18

On Thu, Nov 23, 2006 at 08:50:56AM +0000, Al Viro wrote:
> On Thu, Nov 23, 2006 at 03:22:44AM -0500, Mathieu Desnoyers wrote:
> > Fix file and directory removal in libfs. Add inotify support for file removal.
> > 
> > The following scenario :
> > create dir a
> > create dir a/b
> > 
> > cd a/b (some process goes in cwd a/b)
> > 
> > rmdir a/b
> > rmdir a
> >
> > fails due to the fact that "a" appears to be non empty.
> 
> What?  Caller will do d_delete() itself.  Care to show a version where
> that would happen and post an strace of the second rmdir?
> 
> > It is because the "b"
> > dentry is not deleted from "a" and still in use. The same problem happens if
> > "b" is a file. d_delete is nice enough to know when it needs to unhash and free
> > the dentry if nothing else is using it or, if someone is using it, to remove it
> > from the hash queues and wait for it to be deleted when it has no users.
> > 
> > The nice side-effect of this fix is that it calls the file removal
> > notification.
> 
> NAK.  First of all, I won't believe you without actual strace.
> 
> What's more, WTF would fs _method_ call idiotify?  Keep that crap
> out of filesystems; caller will do it for us just fine.

PS: debugfs, sysfs et sodding alia should take care to do things equivalent
to vfs_unlink(), etc.  _That_ is definitive user of fs methods, which, in
turn, sets the rules for library helpers used by such.
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