[Lustre-devel] Lustre dcache clean up and distributed locking

[Peng Tao]

On Sat, Feb 11, 2012 at 4:37 AM, Andreas Dilger <adilger at whamcloud.com> wrote:
> On 2012-02-09, at 12:15 AM, <tao.peng at emc.com> <tao.peng at emc.com> wrote:
>> Fan Yong <yong.fan at whamcloud.com> wrote:
>>> We has another way to remove Lustre special dentry flags
>>> "DCACHE_LUSTRE_INVALID". To indicate the dentry in dcache without LOOKUP
>>> lock protected but not unhashed yet, we can add new flags in
>>> "ll_dentry_data" (pointed by "dentry::d_fsdata"). Since it is Lustre
>>> private date, no need to worry about whether the new flags will conflict
>>> with any other VFS standard "dentry::d_flags" or not, and maybe save
>>> some effort to implement the complex DENTRY lock in your original design.
>>
>> Hi Fan Yong,
>>
>> Thanks for your great suggestion. I updated the design doc with following changes, please help to review. Thank you!
>>
>> Changelog:
>> 1. Macro cleanups are removed. I prefer to do it separately while cleaning up other obsolete macros.
>> 2. Remove DENTRY LDLM lock proposal. Because DCACHE_LUSTRE_INVALID flag can be hidden from generic VFS layer, it is no longer necessary to introduce such complex change.
>> 3. Add a section to describe how to add LLD_LUSTRE_INVALID flag to ll_dentry_data structure to replace existing DCACHE_LUSTRE_INVALID flag.
>
> Hi Tao,
Hi Andreas,

> these cleanups look quite reasonable now.  Will you be working on making
> these changes for Lustre?  The feature freeze for the Lustre 2.2 release
> was Jan 7, so any non-bugfix changes will need to land for Lustre 2.3.
>
Yes, it is on my todo list. Our plan is for me to first work on
removing the outdated configure macros and related code that are there
to support older (older than 2.6.18-latest) kernels. Then I will work
on the dcache cleanups based on top of the most recent dcache RCU walk
patch.

> However, that doesn't prevent you from working on these patches and sending
> them to Gerrit for inspection, testing, and getting them ready for landing.
> You should base your patch on top of the most recent dcache patch in
>
> http://review.whamcloud.com/1865
>
> If you haven't looked already, please read the following wiki pages:
>
> http://wiki.whamcloud.com/display/PUB/Submitting+Changes
> http://wiki.whamcloud.com/display/PUB/Using+Gerrit
>
> for details on how to submit patches to Gerrit for review/testing/landing.
>
Thanks for sharing the links. I will make sure all patches follow the
guidelines.

Best,
Tao
>
>
> Cheers, Andreas
> --
> Andreas Dilger                       Whamcloud, Inc.
> Principal Lustre Engineer            http://www.whamcloud.com/
>
>
>
>