Re: [f2fs-dev] [PATCH v4 4/4] f2fs: fix inline data not being written to disk in writeback path

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

On 2026/3/17 19:56, Yongpeng Yang wrote:
> From: Yongpeng Yang <yangyongpeng@xiaomi.com>
> 
> When f2fs_fiemap() is called with `fileinfo->fi_flags` containing the
> FIEMAP_FLAG_SYNC flag, it attempts to write data to disk before
> retrieving file mappings via filemap_write_and_wait(). However, there is
> an issue where the file does not get mapped as expected. The following
> scenario can occur:
> 
> root@vm:/mnt/f2fs# dd if=/dev/zero of=data.3k bs=3k count=1
> root@vm:/mnt/f2fs# xfs_io data.3k -c "fiemap -v 0 4096"
> data.3k:
>   EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
>     0: [0..5]:          0..5                 6 0x307
> 
> The root cause of this issue is that f2fs_write_single_data_page() only
> calls f2fs_write_inline_data() to copy data from the data folio to the
> inode folio, and it clears the dirty flag on the data folio. However, it
> does not mark the data folio as writeback. When
> __filemap_fdatawait_range() checks for folios with the writeback flag,
> it returns early, causing f2fs_fiemap() to report that the file has no
> mapping.
> 
> To fix this issue, the solution is to call
> f2fs_write_single_node_folio() in f2fs_inline_data_fiemap() when
> getting fiemap with FIEMAP_FLAG_SYNC flags. This patch ensures that the
> inode folio is written back and the writeback process completes before
> proceeding.
> 
> Fixes: 9ffe0fb5f3bb ("f2fs: handle inline data operations")
> Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
> ---
> v4:
> - Fix the missing return value check for f2fs_get_inode_folio().
> v3:
> - Call f2fs_write_single_node_folio() instead of f2fs_sync_node_pages()
> v2:
> - Call f2fs_sync_node_pages() in getting fiemap path rather than
> writeback path.
> ---
>   fs/f2fs/inline.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 

Declaration should be relocated into this patch.

+int f2fs_write_single_node_folio(struct folio *node_folio, int sync_mode,
+			bool mark_dirty, enum iostat_type io_type);

Thanks,

> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> index 86d2abbb40ff..62a8a1192a41 100644
> --- a/fs/f2fs/inline.c
> +++ b/fs/f2fs/inline.c
> @@ -814,6 +814,15 @@ int f2fs_inline_data_fiemap(struct inode *inode,
>   		goto out;
>   	}
>   
> +	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC) {
> +		err = f2fs_write_single_node_folio(ifolio, true, false, FS_NODE_IO);
> +		if (err)
> +			return err;
> +		ifolio = f2fs_get_inode_folio(F2FS_I_SB(inode), inode->i_ino);
> +		if (IS_ERR(ifolio))
> +			return PTR_ERR(ifolio);
> +		f2fs_folio_wait_writeback(ifolio, NODE, true, true);
> +	}
>   	ilen = min_t(size_t, MAX_INLINE_DATA(inode), i_size_read(inode));
>   	if (start >= ilen)
>   		goto out;



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