[PATCH v7 0/7] Add O_DENY* support for VFS and CIFS/NFS

[Pavel Shilovsky]

2014/1/20 Volker Lendecke <Volker.Lendecke at sernet.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.