Re: [PATCH v2] xfs: bound logged region access in inode buffer recovery

[Hongling Zeng <zhongling0719@126.com>]

在 2026年09月09日 07:00, Dave Chinner 写道:
> On Tue, Sep 08, 2026 at 03:48:03PM +0800, Hongling Zeng wrote:
>> 在 2026年09月08日 14:33, Dave Chinner 写道:
>>> Don't take the design doc as being complete or correct - it's a
>>> working document and really only serves as the initial high level
>>> plan I fleshed out.
>>>
>>> Indeed, I implemented a chunk of it yesterday afternoon (i.e.
>>> before I saw your patch this morning) and my findings change quite a
>>> bit of the generic infrastructure to make it handle the transaction
>>> header without having to special case it. So from that perspective,
>>> it's already out of date...
>>>
>>> I'll post what I have in the series later this afternoon so you can
>>> get up to speed.
> Ok, I just posted my current WIP to the log-verification-1 branch in
> my kernel.org repo
> (https://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs.git)
>
> This is completely untested, I've only made sure it compiles. Don't
> expect it to work. If you do start adding to it, build on top of it
> and point me to the git repo where all your new work can be found.
>
> What I've implemented so far is the refactoring necessary to
> implement generic handling of log item verification and decoding,
> converted the special case transhdr decoding to use the generic
> infrastructure, and implemented fairly complete ophdr validation,
> including validation of the log unmount record (which isn't
> validated in any way right now).
>
> Design has changed to use methods for item specific region count
> checking, as well as adding a completion method that allows item
> types to consume the item rather than queuing it for later recovery
> (both needed for the transhdr conversion). Implementation has been
> refined to avoid decoding ophdrs until sufficient validation has
> been performed to guarantee the buffer pointer is sane and is long
> enough to contain a full ophdr, and then it valdates the rest of the
> ophdr before passing it to the processing code.
>
> The next steps are to start implementing the per-item type
> validation functions.
>
> I also noticed that the head/tail search code that reads log
> record headers doesn't really do much validation on the log record
> headers. We probably need to address that, too, so we can detect
> corrupted headers during the head/tail search and avoid finding
> incorrect head/tail records as a result.
>
>> Once your series is posted I'll start with review and the
>> recoveryloop / logprint-based testing, then take the per-type
>> validate_region() / validate_item() implementations on top of your
>> iterator.
> I think it's probably better that you first read the code yourself
> and develop an understanding of what needs to be done without the
> aid of an LLM. See if you can find bugs in what I've already done
> -without- an LLM - you will learn the code at the same time, and
> then be in a much better place to guide an LLM through later stages
> of development.
>
> Cheers,
>
> Dave.
>
Thanks for posting the WIP series.

I’ll work from the log-verification-1 branch and first study the generic
iterator and item handling rather than extending the old special cases.
I’ll pay particular attention to arbitrary continuation fragments,
zero-length first fragments, transaction-header completion, and cleanup
on malformed input.

I’ll review the existing code for bugs before adding the per-item 
validation functions, and will point you to my repository once I have
work based on the branch.

Thanks,
Hongling