Hi Xiang,
On 2024/6/28 15:39, Gao Xiang wrote:
Hi Baokun,
On 2024/6/28 14:29, libaokun@xxxxxxxxxxxxxxx wrote:
From: Baokun Li <libaokun1@xxxxxxxxxx>
Hi all!
This is the third version of this patch series, in which another
patch set
is subsumed into this one to avoid confusing the two patch sets.
(https://patchwork.kernel.org/project/linux-fsdevel/list/?series=854914)
Thank you, Jia Zhu, Gao Xiang, Jeff Layton, 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 series fixes some of the issues. The patches have passed internal
testing without regression.
The following is a brief overview of the patches, see the patches for
more details.
Patch 1-2: Add fscache_try_get_volume() helper function to avoid
fscache_volume use-after-free on cache withdrawal.
Patch 3: Fix cachefiles_lookup_cookie() and cachefiles_withdraw_cache()
concurrency causing cachefiles_volume use-after-free.
Patch 4: Propagate error codes returned by vfs_getxattr() to avoid
endless loops.
Patch 5-7: 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 8: Cyclic allocation of msg_id to avoid msg_id reuse misleading
the daemon to cause hung.
Patch 9: 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 is pushed upstream as well.
Comments and questions are, as always, welcome.
Please let me know what you think.
Patch 4-9 looks good to me, and they are independent to patch 1-3
so personally I guess they could go upstream in advance.
Thank you for your review!
Indeed, the first three patches have no dependencies on the later
ones, and the later ones can be merged in first.
I hope the way to fix cachefiles in patch 1-4 could be also
confirmed by David and Jeff since they relates the generic
cachefiles logic anyway.
Yes, the first four patches modify the generic process for cachefiles,
and it would be great if David and Jeff could take a look at those.
The logic for patches 2 and 3 is a bit more complex, so the review
may take some time.
Cheers,
Baokun
