[OT] Hardlinks and directories
fatkasuvayu+linux at gmail.com
Sat Feb 13 03:28:01 UTC 2010
On Friday 12 February 2010 05:56 PM, Patrick O'Callaghan wrote:
> On Fri, 2010-02-12 at 16:02 -0800, Suvayu Ali wrote:
>> On Friday 12 February 2010 05:41 AM, Patrick O'Callaghan wrote:
>>> On Thu, 2010-02-11 at 23:23 -0800, Suvayu Ali wrote:
>> Okay, I now understand the aspect of "." and ".." being the only two
>> hardlinks allowed for directories. However in the lwn discussion I
>> linked to in my OP, one poster mentions the special case of a chroot.
>> Does that mean this is something the kernel(?) decides for us, Or is it
>> this treatment of "." and ".." universal?
> I'm not sure I understand what you're asking here. If something is
> decided by the kernel, surely it's universal isn't it?
By universal I meant something determined by the filesystem. Would the
restriction still be there if I were to use ext4 with a kernel
(something other than linux) that supported such hardlinks?
>> So essentially since hardlinks deal with inodes directly, the best way
>> to prevent the problem of recursion is to proactively forbid it instead
>> of using external checks like keeping count?
> Either would do, but I suspect Ken and Dennis thought the "no hard links
> to directories" rule was easier to implement. It's certainly more
> One of the comments to the LWN article also mentions the case of Apple
> allowing these links for the sake of their Time Machine backup system (I
> think it's restricted to that special case so it doesn't run the risk of
> a general-purpose feature). Presumably that's the main reason TM doesn't
> work with non-Apple partitions, despite several NAS manufacturers
> advertising that it does. I just bought an Iomega NAS partly on the
> strength of this and it definitely doesn't work.
I think this resolves almost all my questions. :)
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