Re: [f2fs-dev] [PATCH 1/2] f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage

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

On 3/10/26 17:36, Yongpeng Yang wrote:
> From: Yongpeng Yang <yangyongpeng@xiaomi.com>
> 
> f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion
> with the checkpoint path, which can result in an incorrect inode block
> marking state. The scenario is as follows:
> 
> create & write & fsync 'file A'                 write checkpoint
> - f2fs_do_sync_file // inline inode
>  - f2fs_write_inode // inode folio is dirty
>                                                 - f2fs_write_checkpoint
>                                                  - f2fs_flush_merged_writes
>                                                  - f2fs_sync_node_pages
>  - f2fs_fsync_node_pages // no dirty node
>  - f2fs_need_inode_block_update // return true
>  - f2fs_fsync_node_pages // inode dirtied
>   - f2fs_need_dentry_mark //return true
>                                                  - f2fs_flush_nat_entries
>                                                 - f2fs_write_checkpoint end
>   - __write_node_folio // inode with DENT_BIT_SHIFT set
>   SPO, "fsck --dry-run" find inode has already checkpointed but still
>   with DENT_BIT_SHIFT set
> 
> The state observed by f2fs_need_dentry_mark() can differ from the state
> observed in __write_node_folio() after acquiring sbi->node_write. The
> root cause is that the semantics of IS_CHECKPOINTED and
> HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has
> fully completed.
> 
> This patch moves set_dentry_mark() into __write_node_folio() and
> protects it with the sbi->node_write lock.
> 

Cc: stable@kernel.org

> Fixes: 88bd02c9472a ("f2fs: fix conditions to remain recovery information in f2fs_sync_file")
> Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,


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