Re: RFC: renameat(): Add a RENAME_REMOVE flag to unlink hardlinks

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Nov 21, 2014 at 10:39 AM, Pádraig Brady <P@xxxxxxxxxxxxxx> wrote:
> On 21/11/14 18:09, Andy Lutomirski wrote:
>> On Fri, Nov 21, 2014 at 6:17 AM, Pádraig Brady <P@xxxxxxxxxxxxxx> wrote:
>>> If 'a' and 'b' are hardlinks, then the command `mv a b & mv b a`
>>> can result in both being removed as mv needs to emulate the
>>> move with an unlink of the source file.  This can only be done
>>> without races in the kernel and so mv was recently changed
>>> to not allow this operation at all.  mv could safely reintroduce
>>> this feature by leveraging a new flag for renameat() for which
>>> an illustrative/untested patch is attached.
>>
>> ISTM the issue is that rename(2) does nothing if the source and dest
>> are hardlinks to each other.  Is that intentional?  I don't see that
>> behavior as required in the POSIX rename docs.
>
> It's surprising and annoying that existing systems do this,
> but they're conforming to the wording of POSIX I thinkg as
> it says that rename() does nothing when the source and dest
> _file_ is the same. What POSIX really meant I suppose was _file name_.
> Eric, perhaps an adjustment could be proposed to POSIX, as I can't
> see anything relying on the current behavior?

Which Eric?

--Andy

>
>> If we indeed need to keep that behavior around for legacy reasons,
>> then can we at least give RENAME_REMOVE a better name?
>
> Definitely not attached to the name :)
> Let's see if we can change it without a flag, though I guess
> that would mean that mv on older systems would
> silently do nothing in this case.
>
> thanks,
> Pádraig.
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux