Re: [f2fs-dev] [PATCH] f2fs: fix incorrect FI_NO_EXTENT handling in __destroy_extent_node()

[Yongpeng Yang <monty_pavel@sina.com>]

On 4/22/26 20:33, Chao Yu via Linux-f2fs-devel wrote:
> On 4/22/2026 3:35 PM, Yongpeng Yang wrote:
>> From: yangyongpeng <yangyongpeng@xiaomi.com>
>>
>> When __destroy_extent_node() sets the inode flag FI_NO_EXTENT, it does
>> not reset the length of the largest extent to 0 and update the inode
>> folio. Since modifications to the extent tree are disallowed afterward,
>> the cached largest extent may become stale. This can trigger the
>> following error in xfstests generic/388:
>>
>> F2FS-fs (dm-0): sanity_check_extent_cache: inode (ino=1761) extent
>> info [220057, 57, 6] is incorrect, run fsck to fix
>>
>> In the f2fs_drop_inode path, __destroy_extent_node() does not need to
>> guarantee that et->node_cnt is 0, because concurrency with writeback
>> is expected in this path, and writeback may update the extent cache.
>>
>> This patch updates __destroy_extent_node() to avoid setting the inode
>> flag FI_NO_EXTENT, and to remove the check zero of et->node_cnt.
>>
>> Fixes: ed78aeebef05 ("f2fs: fix node_cnt race between extent node
>> destroy and writeback")
>> Cc: stable@vger.kernel.org
>> Reported-by: Chao Yu <chao@kernel.org>
>> Suggested-by: Chao Yu <chao@kernel.org>
>> Signed-off-by: yangyongpeng <yangyongpeng@xiaomi.com>
>> ---
>>   fs/f2fs/extent_cache.c | 4 ----
>>   1 file changed, 4 deletions(-)
>>
>> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
>> index 87169fd29d89..3adbead27953 100644
>> --- a/fs/f2fs/extent_cache.c
>> +++ b/fs/f2fs/extent_cache.c
>> @@ -645,14 +645,10 @@ static unsigned int __destroy_extent_node(struct
>> inode *inode,
>>         while (atomic_read(&et->node_cnt)) {
>>           write_lock(&et->lock);
>> -        if (!is_inode_flag_set(inode, FI_NO_EXTENT))
>> -            set_inode_flag(inode, FI_NO_EXTENT);
> 
> We'd better revert all change lines in "f2fs: fix node_cnt race between
> extent node destroy and writeback"?

The others all check whether FI_NO_EXTENT is set. When it is set,
inserting an age extent is disallowed, so nothing was removed.

Thanks
Yongpeng,

> 
> Thanks,
> 
>>           node_cnt += __free_extent_tree(sbi, et, nr_shrink);
>>           write_unlock(&et->lock);
>>       }
>>   -    f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
>> -
>>       return node_cnt;
>>   }
>>   
> 
> 
> 
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