Re: [PATCH 07/11] fs: consolidate fsverity_info lookup in buffer.c

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Jan 22, 2026 at 09:22:03AM +0100, Christoph Hellwig wrote:
> Look up the fsverity_info once in end_buffer_async_read_io, and then
> pass it along to the I/O completion workqueue in
> struct postprocess_bh_ctx.
> 
> This amortizes the lookup better once it becomes less efficient.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/buffer.c | 27 +++++++++++----------------
>  1 file changed, 11 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 3982253b6805..f4b3297ef1b1 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -302,6 +302,7 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
>  struct postprocess_bh_ctx {
>  	struct work_struct work;
>  	struct buffer_head *bh;
> +	struct fsverity_info *vi;
>  };
>  
>  static void verify_bh(struct work_struct *work)
> @@ -309,25 +310,14 @@ static void verify_bh(struct work_struct *work)
>  	struct postprocess_bh_ctx *ctx =
>  		container_of(work, struct postprocess_bh_ctx, work);
>  	struct buffer_head *bh = ctx->bh;
> -	struct inode *inode = bh->b_folio->mapping->host;
>  	bool valid;
>  
> -	valid = fsverity_verify_blocks(*fsverity_info_addr(inode), bh->b_folio,
> -				       bh->b_size, bh_offset(bh));
> +	valid = fsverity_verify_blocks(ctx->vi, bh->b_folio, bh->b_size,
> +				       bh_offset(bh));
>  	end_buffer_async_read(bh, valid);
>  	kfree(ctx);
>  }
>  
> -static bool need_fsverity(struct buffer_head *bh)
> -{
> -	struct folio *folio = bh->b_folio;
> -	struct inode *inode = folio->mapping->host;
> -
> -	return fsverity_active(inode) &&
> -		/* needed by ext4 */
> -		folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
> -}
> -
>  static void decrypt_bh(struct work_struct *work)
>  {
>  	struct postprocess_bh_ctx *ctx =
> @@ -337,7 +327,7 @@ static void decrypt_bh(struct work_struct *work)
>  
>  	err = fscrypt_decrypt_pagecache_blocks(bh->b_folio, bh->b_size,
>  					       bh_offset(bh));
> -	if (err == 0 && need_fsverity(bh)) {
> +	if (err == 0 && ctx->vi) {
>  		/*
>  		 * We use different work queues for decryption and for verity
>  		 * because verity may require reading metadata pages that need
> @@ -359,15 +349,20 @@ static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
>  {
>  	struct inode *inode = bh->b_folio->mapping->host;
>  	bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
> -	bool verify = need_fsverity(bh);
> +	struct fsverity_info *vi = NULL;
> +
> +	/* needed by ext4 */
> +	if (bh->b_folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
> +		vi = fsverity_get_info(inode);

Well this is no longer a weird ext4ism, since f2fs also needs this,
right?  Maybe this comment should read:

	/*
	 * Merkle tree folios can be cached in the pagecache, but they
	 * must never be cached below the first base page offset beyond
	 * EOF because mmap can expose address space beyond EOF.
	 */
	if (bh->b_folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))

--D

>  
>  	/* Decrypt (with fscrypt) and/or verify (with fsverity) if needed. */
> -	if (uptodate && (decrypt || verify)) {
> +	if (uptodate && (decrypt || vi)) {
>  		struct postprocess_bh_ctx *ctx =
>  			kmalloc(sizeof(*ctx), GFP_ATOMIC);
>  
>  		if (ctx) {
>  			ctx->bh = bh;
> +			ctx->vi = vi;
>  			if (decrypt) {
>  				INIT_WORK(&ctx->work, decrypt_bh);
>  				fscrypt_enqueue_decrypt_work(&ctx->work);
> -- 
> 2.47.3
> 
>