Re: [PATCH 04/14] ext4, fscrypt: merge fscrypt_mergeable_bio_bh into io_submit_need_new_bio

[Eric Biggers <ebiggers@kernel.org>]

On Thu, Feb 26, 2026 at 06:49:24AM -0800, Christoph Hellwig wrote:
> ext4 already has the inode and folio and can't have a NULL
> folio->mapping in this path. Open code fscrypt_mergeable_bio_bh in
> io_submit_need_new_bio based on these simplifying assumptions.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/crypto/inline_crypt.c | 23 -----------------------
>  fs/ext4/page-io.c        |  8 ++++++--
>  include/linux/fscrypt.h  |  9 ---------
>  3 files changed, 6 insertions(+), 34 deletions(-)
> 
> diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
> index c0852b920dbc..0da53956a9b1 100644
> --- a/fs/crypto/inline_crypt.c
> +++ b/fs/crypto/inline_crypt.c
> @@ -406,29 +406,6 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
>  }
>  EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio);
>  
> -/**
> - * fscrypt_mergeable_bio_bh() - test whether data can be added to a bio
> - * @bio: the bio being built up
> - * @next_bh: the next buffer_head for which I/O will be submitted
> - *
> - * Same as fscrypt_mergeable_bio(), except this takes a buffer_head instead of
> - * an inode and block number directly.
> - *
> - * Return: true iff the I/O is mergeable
> - */
> -bool fscrypt_mergeable_bio_bh(struct bio *bio,
> -			      const struct buffer_head *next_bh)
> -{
> -	const struct inode *inode;
> -	u64 next_lblk;
> -
> -	if (!bh_get_inode_and_lblk_num(next_bh, &inode, &next_lblk))
> -		return !bio->bi_crypt_context;
> -
> -	return fscrypt_mergeable_bio(bio, inode, next_lblk);
> -}
> -EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio_bh);
> -
>  /**
>   * fscrypt_dio_supported() - check whether DIO (direct I/O) is supported on an
>   *			     inode, as far as encryption is concerned
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index 88226979c503..3db3c19a29e5 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -441,11 +441,15 @@ static void io_submit_init_bio(struct ext4_io_submit *io,
>  }
>  
>  static bool io_submit_need_new_bio(struct ext4_io_submit *io,
> +				   struct inode *inode,
> +				   struct folio *io_folio,
>  				   struct buffer_head *bh)
>  {
>  	if (bh->b_blocknr != io->io_next_block)
>  		return true;
> -	if (!fscrypt_mergeable_bio_bh(io->io_bio, bh))
> +	if (!fscrypt_mergeable_bio(io->io_bio, inode,
> +			(folio_pos(io_folio) + bh_offset(bh)) >>
> +			 inode->i_blkbits))
>  		return true;
>  	return false;
>  }
> @@ -456,7 +460,7 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
>  			     struct folio *io_folio,
>  			     struct buffer_head *bh)
>  {
> -	if (io->io_bio && io_submit_need_new_bio(io, bh)) {
> +	if (io->io_bio && io_submit_need_new_bio(io, inode, io_folio, bh)) {
>  submit_and_retry:
>  		ext4_io_submit(io);
>  	}

As in patch 2, this needs to use 'folio', not 'io_folio'.

- Eric