linux-kernel - Re: [PATCH v2 0/5] cachefiles: some bugfixes for clean object/send req/poll

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Date: Wed, 26 Jun 2024 11:04:30 +0800
From: Baokun Li <libaokun@...weicloud.com>
To: netfs@...ts.linux.dev, dhowells@...hat.com, jlayton@...nel.org
Cc: hsiangkao@...ux.alibaba.com, jefflexu@...ux.alibaba.com,
 zhujia.zj@...edance.com, linux-erofs@...ts.ozlabs.org,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 yangerkun@...wei.com, houtao1@...wei.com, yukuai3@...wei.com,
 wozizhi@...wei.com, Baokun Li <libaokun1@...wei.com>
Subject: Re: [PATCH v2 0/5] cachefiles: some bugfixes for clean object/send
 req/poll

A gentle ping.

On 2024/5/15 20:51, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
>
> Hi all!
>
> This is the second version of this patch series. Thank you, Jia Zhu and
> Gao Xiang, for the feedback in the previous version.
>
> We've been testing ondemand mode for cachefiles since January, and we're
> almost done. We hit a lot of issues during the testing period, and this
> patch set fixes some of the issues related to reopen worker/send req/poll.
> The patches have passed internal testing without regression.
>
> Patch 1-3: A read request waiting for reopen could be closed maliciously
> before the reopen worker is executing or waiting to be scheduled. So
> ondemand_object_worker() may be called after the info and object and even
> the cache have been freed and trigger use-after-free. So use
> cancel_work_sync() in cachefiles_ondemand_clean_object() to cancel the
> reopen worker or wait for it to finish. Since it makes no sense to wait
> for the daemon to complete the reopen request, to avoid this pointless
> operation blocking cancel_work_sync(), Patch 1 avoids request generation
> by the DROPPING state when the request has not been sent, and Patch 2
> flushes the requests of the current object before cancel_work_sync().
>
> Patch 4: Cyclic allocation of msg_id to avoid msg_id reuse misleading
> the daemon to cause hung.
>
> Patch 5: Hold xas_lock during polling to avoid dereferencing reqs causing
> use-after-free. This issue was triggered frequently in our tests, and we
> found that anolis 5.10 had fixed it, so to avoid failing the test, this
> patch was pushed upstream as well.
>
> Comments and questions are, as always, welcome.
> Please let me know what you think.
>
> Thanks,
> Baokun
>
> Changes since v1:
>    * Collect RVB from Jia Zhu and Gao Xiang.(Thanks for your review!)
>    * Pathch 1,2：Add more commit messages.
>    * Pathch 3：Add Fixes tag as suggested by Jia Zhu.
>    * Pathch 4：No longer changing "do...while" to "retry" to focus changes
>      and optimise commit messages.
>    * Pathch 5: Drop the internal RVB tag.
>
> [V1]: https://lore.kernel.org/all/20240424033409.2735257-1-libaokun@huaweicloud.com
>
> Baokun Li (3):
>    cachefiles: stop sending new request when dropping object
>    cachefiles: flush all requests for the object that is being dropped
>    cachefiles: cyclic allocation of msg_id to avoid reuse
>
> Hou Tao (1):
>    cachefiles: flush ondemand_object_worker during clean object
>
> Jingbo Xu (1):
>    cachefiles: add missing lock protection when polling
>
>   fs/cachefiles/daemon.c   |  4 ++--
>   fs/cachefiles/internal.h |  3 +++
>   fs/cachefiles/ondemand.c | 52 +++++++++++++++++++++++++++++++++++-----
>   3 files changed, 51 insertions(+), 8 deletions(-)
>

-- 
With Best Regards,
Baokun Li