Re: [f2fs-dev] [PING][PATCH] f2fs: force out‑place update for all writes on compressed file

[Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

On 9/7/26 16:45, Jiucheng Xu wrote:
> On 9/7/2026 3:08 PM, Chao Yu wrote:
>> [ EXTERNAL EMAIL ]
>>
>> On 9/2/26 11:18, Jiucheng Xu wrote:
>>
>> Jiucheng,
>>
>> Sorry for delay reply.
>>
>>
>> I didn't get it, can you please describe the issue w/ call stack in race
>> condition?
>>
> Hi Chao,
> 
> Thanks for your time, The call stack is shown as below:
> 
> -Thread A                                         - Thread B
>   - f2fs_write_multi_pages                          -
> f2fs_down_write(&sbi->cp_rwsem);
>    - f2fs_write_compressed_pages                    - ...
>     - f2fs_trylock_op                               - ...
>      - f2fs_down_read_trylock(&sbi->cp_rwsem);      - ...
>    - f2fs_write_raw_pages                           - ...
> 
> Thread B acquires the lock first, which causes Thread A to fail lock
> acquisition and fall back to raw‑data write.
> IPU_FORCE is enabled on 16G eMMC platforms, so f2fs_write_raw_pages()
> overwrites the original compressed data in‑place.
> The in‑memory node has been updated with raw‑data addresses, while the
> node metadata stored on eMMC still remains in compressed state.
> If a power‑cut occurs before the node is flushed to disk, on‑disk
> inconsistency arises: The data on disk is raw, but metadata
> still treats it as a compressed cluster and decompression will fail.

Ah, now, I see, thanks for your explanation, can you add above callstack
in commit message as well?

Thanks,


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