Re: [Gluster-devel] regressions due to 64-bit ext4 directory cookies

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

 



On 3/26/13 10:23 AM, Bernd Schubert wrote:
> Sorry for my late reply, I had been rather busy.
> 
> On 02/14/2013 01:05 AM, Anand Avati wrote:
>> On Wed, Feb 13, 2013 at 3:44 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:
>>>
>>> I suspect this would seriously screw over Gluster, though, and this
>>> wouldn't be a solution for NFSv3, since NFS needs long-lived directory
>>> cookies, and not the short-lived cookies which is all POSIX/SuSv3
>>> guarantees.
>>>
>>
>> Actually this would work just fine with Gluster. Except in the case of
> 
> Would it really work perfectly? What about a server reboot in the middle of a readdir of a client?
> 
>> gluster-NFS, the native client is only acting like a router/proxy of
>> syscalls to the backend system. A directory opened by an application will
>> have a matching directory fd opened on ext4, and readdir from an app will
>> be translated into readdir on the matching fd on ext4. So the
>> app-on-glusterfs and glusterfsd-on-ext4 are essentially "moving in tandem".
>> As long as the offs^H^H^H^H cookies do not overflow in the transformation,
>> Gluster would not have a problem.
>>
>> However Gluster-NFS (and NFS in general, too) will break, as we
>> opendir/closedir potentially on every request.
> 
> We don't have reached a conclusion so far, do we? What about the
> ioctl approach, but a bit differently? Would it work to specify the
> allowed upper bits for ext4 (for example 16 additional bit) and the
> remaining part for gluster? One of the mails had the calculation
> formula:

I did throw together an ioctl patch last week, but I think Anand has a new
approach he's trying out which won't require ext4 code changes.  I'll let
him reply when he has a moment.  :)

-Eric

> final_d_off = (ext4_d_off * MAX_SERVERS) + server_idx
> 
> But what is the value of MAX_SERVERS?
> 
> 
> Cheers,
> Bernd
> 
> 
> -- 
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Reiser Filesystem Development]     [Ceph FS]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite National Park]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]     [Linux Media]

  Powered by Linux