Re: [f2fs-dev] [PATCH 11/14] f2fs: fix zeroing paths for large folios

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

On 8/26/26 21:09, Nanzhe Zhao wrote:
> Several f2fs zeroing paths still use PAGE_SIZE based offsets after
> a file mapping can contain large folios.  This is fine for order-0
> folios, but it zeros the wrong range once the target block is not at
> offset 0 in a large folio.
> 
> Use offset_in_folio() to translate the file block index to the folio
> offset before zeroing data in truncate_partial_data_page(), fill_zero(),
> and f2fs_get_new_data_folio().
> 
> Signed-off-by: Nanzhe Zhao <zhaonanzhe@xiaomi.com>
> ---
>   fs/f2fs/data.c | 13 ++++++++++---
>   fs/f2fs/f2fs.h |  1 +
>   fs/f2fs/file.c | 27 ++++++++++++++++++++++-----
>   3 files changed, 33 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 15774e8e8795..0b167b14a9a5 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1582,9 +1582,16 @@ struct folio *f2fs_get_new_data_folio(struct inode *inode,
>   		goto got_it;
>   
>   	if (dn.data_blkaddr == NEW_ADDR) {
> -		folio_zero_segment(folio, 0, folio_size(folio));
> -		if (!folio_test_uptodate(folio))
> +		size_t off = offset_in_folio(folio,
> +					(loff_t)index << PAGE_SHIFT);
> +
> +		folio_zero_segment(folio, off, off + PAGE_SIZE);
> +		if (folio_test_large(folio)) {
> +			f2fs_ffs_find_or_alloc(folio);
> +			f2fs_ffs_mark_subrange_uptodate(folio, off, PAGE_SIZE);
> +		} else if (!folio_test_uptodate(folio)) {
>   			folio_mark_uptodate(folio);
> +		}
>   	} else {
>   		f2fs_folio_put(folio, true);
>   
> @@ -2670,7 +2677,7 @@ static bool __ffs_mark_subrange_uptodate(struct folio *folio,
>   	return bitmap_full(ffs->state, nr_subpages);
>   }
>   
> -static void f2fs_ffs_mark_subrange_uptodate(struct folio *folio, size_t offset,
> +void f2fs_ffs_mark_subrange_uptodate(struct folio *folio, size_t offset,
>   				       size_t len)
>   {
>   	struct f2fs_folio_state *ffs;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 0ffbe2bd04c8..6ae249bf9aa1 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4330,6 +4330,7 @@ struct folio *f2fs_get_lock_data_folio(struct inode *inode, pgoff_t index,
>   			bool for_write);
>   struct folio *f2fs_get_new_data_folio(struct inode *inode,
>   			struct folio *ifolio, pgoff_t index, bool new_i_size);
> +void f2fs_ffs_mark_subrange_uptodate(struct folio *folio, size_t offset, size_t len);
>   int f2fs_do_write_data_page(struct f2fs_io_info *fio);
>   int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag);
>   int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 02d687527241..4272013dbe38 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -811,12 +811,12 @@ void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
>   static int truncate_partial_data_page(struct inode *inode, u64 from,
>   								bool cache_only)
>   {
> -	loff_t offset = from & (PAGE_SIZE - 1);
>   	pgoff_t index = from >> PAGE_SHIFT;
>   	struct address_space *mapping = inode->i_mapping;
>   	struct folio *folio;
> +	size_t folio_off;
>   
> -	if (!offset && !cache_only)
> +	if (!(from & (PAGE_SIZE - 1)) && !cache_only)
>   		return 0;
>   
>   	if (cache_only) {
> @@ -834,12 +834,21 @@ static int truncate_partial_data_page(struct inode *inode, u64 from,

Actually, I think it tries to truncate partial *data block* post EOF.

>   		return PTR_ERR(folio) == -ENOENT ? 0 : PTR_ERR(folio);
>   truncate_out:
>   	f2fs_folio_wait_writeback(folio, DATA, true, true);
> -	folio_zero_segment(folio, offset, folio_size(folio));
> +	folio_off = offset_in_folio(folio, from);
> +	folio_zero_segment(folio, folio_off, folio_size(folio));
>   
>   	/* An encrypted inode should have a key and truncate the last page. */
>   	f2fs_bug_on(F2FS_I_SB(inode), cache_only && IS_ENCRYPTED(inode));
> -	if (!cache_only)
> +	if (!cache_only) {
> +		if (folio_test_large(folio)) {
> +			f2fs_ffs_find_or_alloc(folio);
> +			f2fs_ffs_mark_subrange_uptodate(folio, folio_off,
> +					folio_size(folio) - folio_off);
> +			f2fs_ffs_mark_subrange_dirty(folio, folio_off,
> +					folio_size(folio) - folio_off);

So I guess we can only mark uptodate/dirty in ffs in extent of (folio_off, PAGE_SIZE)?

> +		}
>   		folio_mark_dirty(folio);
> +	}
>   	f2fs_folio_put(folio, true);
>   	return 0;
>   }
> @@ -1310,6 +1319,7 @@ static int fill_zero(struct inode *inode, pgoff_t index,
>   	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>   	struct folio *folio;
>   	struct f2fs_lock_context lc;
> +	size_t folio_off;
>   
>   	if (!len)
>   		return 0;
> @@ -1324,7 +1334,14 @@ static int fill_zero(struct inode *inode, pgoff_t index,
>   		return PTR_ERR(folio);
>   
>   	f2fs_folio_wait_writeback(folio, DATA, true, true);
> -	folio_zero_range(folio, start, len);
> +	folio_off = offset_in_folio(folio,
> +				   (loff_t)index << PAGE_SHIFT) + start;
> +	folio_zero_range(folio, folio_off, len);
> +	if (folio_test_large(folio)) {
> +		f2fs_ffs_find_or_alloc(folio);
> +		f2fs_ffs_mark_subrange_uptodate(folio, folio_off, len);
> +		f2fs_ffs_mark_subrange_dirty(folio, folio_off, len);

Ditto,

Thanks,

> +	}
>   	folio_mark_dirty(folio);
>   	f2fs_folio_put(folio, true);
>   	return 0;



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