Re: [f2fs-dev] [PATCH v2 1/2] f2fs: add 'folio_in_bio' to handle readahead folios with no BIO submission

[Chao Yu <chao@kernel.org>]

On 1/11/2026 6:09 PM, Nanzhe Zhao wrote:
> f2fs_read_data_large_folio() can build a single read BIO across multiple
> folios during readahead. If a folio ends up having none of its subpages
> added to the BIO (e.g. all subpages are zeroed / treated as holes), it
> will never be seen by f2fs_finish_read_bio(), so folio_end_read() is
> never called. This leaves the folio locked and not marked uptodate.
> 
> Track whether the current folio has been added to a BIO via a local
> 'folio_in_bio' bool flag, and when iterating readahead folios, explicitly
> mark the folio uptodate (on success) and unlock it when nothing was added.
> 
> Signed-off-by: Nanzhe Zhao <nzzhao@126.com>
> ---
>   fs/f2fs/data.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index f32eb51ccee4..ddabcb1b9882 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -2436,6 +2436,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
>   	unsigned nrpages;
>   	struct f2fs_folio_state *ffs;
>   	int ret = 0;
> +	bool folio_in_bio;
> 
>   	if (!IS_IMMUTABLE(inode))
>   		return -EOPNOTSUPP;
> @@ -2451,6 +2452,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
>   	if (!folio)
>   		goto out;
> 
> +	folio_in_bio = false;
>   	index = folio->index;
>   	offset = 0;
>   	ffs = NULL;
> @@ -2536,6 +2538,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
>   					offset << PAGE_SHIFT))
>   			goto submit_and_realloc;
> 
> +		folio_in_bio = true;
>   		inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
>   		f2fs_update_iostat(F2FS_I_SB(inode), NULL, FS_DATA_READ_IO,
>   				F2FS_BLKSIZE);
> @@ -2545,6 +2548,11 @@ static int f2fs_read_data_large_folio(struct inode *inode,
>   	}
>   	trace_f2fs_read_folio(folio, DATA);
>   	if (rac) {
> +		if (!folio_in_bio) {
> +			if (!ret)

ret should never be true here?

Thanks,

> +				folio_mark_uptodate(folio);
> +			folio_unlock(folio);
> +		}
>   		folio = readahead_folio(rac);
>   		goto next_folio;
>   	}
> --
> 2.34.1
>