linux-kernel - Re: [PATCH v7 0/7] Add O_DENY* support for VFS and CIFS/NFS

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Date:	Mon, 20 Jan 2014 14:20:43 +0400
From:	Pavel Shilovsky <piastry@...rsoft.ru>
To:	"Volker.Lendecke@...Net.DE" <Volker.Lendecke@...net.de>
Cc:	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-cifs <linux-cifs@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux NFS Mailing list <linux-nfs@...r.kernel.org>,
	wine-devel@...ehq.org
Subject: Re: [PATCH v7 0/7] Add O_DENY* support for VFS and CIFS/NFS

2014/1/20 Volker Lendecke <Volker.Lendecke@...net.de>:
> Hi!
>
> On Fri, Jan 17, 2014 at 02:07:05PM +0400, Pavel Shilovsky wrote:
>> If O_DENYDELETE flag is specified and the open succeded,
>> any further unlink operation will fail with -ESHAREDENIED
>> untill this open is closed. Now this flag is processed by
>> VFS and CIFS filesystem. NFS returns -EINVAL for opens
>> with this flag.
>
> This looks really, really good, thanks!
>
> One question: If Samba wants to open a file for delete
> access, there's no corresponding flag in the open
> permissions. There can be the case where Samba wants to open
> *just* for future unlink, no read or write access required.
> Is there a way to achieve this atomically correct?

You can try to use O_PATH flag. It doesn't give you a delete access
but should be ok because further deleting will be done without file
descriptor -- through unlink syscall.

-- 
Best regards,
Pavel Shilovsky.
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