Re: [PATCH 3/6] ubifs: Use 64bit readdir cookies

[Richard Weinberger]

Bruce,

On 29.12.2016 16:34, J. Bruce Fields wrote:
>> That way UBIFS can provide a 64bit readdir() cookie which is required for NFS3.
> 
> Sounds good.  And if a matching entry isn't found (as in the case of a
> concurrent unlink), what happens?  The answer must be the same as for
> ext4, but I've forgotten the details....  I guess it must find the next
> highest cookie (thinking of the cookie as a 64-bit integer of some kind)
> that exists in the directory.  And that must be the same order that
> readdir normally returns entries in.

If a 64bit cookie is not found, the lookup function returns -ENOENT.
In UBIFS we cannot just select a higher or lower key (cookie in this case),
since it is the B-tree key and would point to a completely different
entry.

So, in case of a concurrent unlink() one would succeed and one fail with
-ENOENT. Unless I miss something that seems okay to me.

Thanks,
//richard