linux-kernel - Re: [PATCH 1/2] bcachefs: Simplify bch2_bio

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Message-ID: <4j4uopk7emegyqrwr3kd7mmdc25ps66prypb3ehfqwo5oqs5pm@ipqb5mdibsml>
Date: Wed, 4 Jun 2025 22:14:38 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Youling Tang <youling.tang@...ux.dev>
Cc: linux-bcachefs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Youling Tang <tangyouling@...inos.cn>
Subject: Re: [PATCH 1/2] bcachefs: Simplify bch2_bio_map()

On Thu, Jun 05, 2025 at 10:06:38AM +0800, Youling Tang wrote:
> From: Youling Tang <tangyouling@...inos.cn>
> 
> For the part of directly mapping the kernel virtual address, there is no
> need to increase to bio page-by-page. It can be directly replaced by
> bio_add_virt_nofail().
> 
> For the address part of the vmalloc region, its physical address is
> discontinuous and needs to be increased page-by-page to bio. The helper
> function bio_add_vmalloc() can be used to simplify the implementation of
> bch2_bio_map().
> 
> Signed-off-by: Youling Tang <tangyouling@...inos.cn>

Thanks, I'll apply these after I rebase on 6.16-rc1.

> ---
> NOTE:
> The following patch needs to be applied (because the bcachefs.git repository
> has not been synchronized to the latest):
> commit 850e210d5ad2 ("block: add a bio_add_virt_nofail helper")
> commit 8dd16f5e3469 ("block: add a bio_add_vmalloc helpers")
> 
>  fs/bcachefs/util.c | 15 ++++-----------
>  1 file changed, 4 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
> index dc3817f545fa..5e5075630bc6 100644
> --- a/fs/bcachefs/util.c
> +++ b/fs/bcachefs/util.c
> @@ -623,17 +623,10 @@ void bch2_pd_controller_debug_to_text(struct printbuf *out, struct bch_pd_contro
>  
>  void bch2_bio_map(struct bio *bio, void *base, size_t size)
>  {
> -	while (size) {
> -		struct page *page = is_vmalloc_addr(base)
> -				? vmalloc_to_page(base)
> -				: virt_to_page(base);
> -		unsigned offset = offset_in_page(base);
> -		unsigned len = min_t(size_t, PAGE_SIZE - offset, size);
> -
> -		BUG_ON(!bio_add_page(bio, page, len, offset));
> -		size -= len;
> -		base += len;
> -	}
> +	if (is_vmalloc_addr(base))
> +		bio_add_vmalloc(bio, base, size);
> +	else
> +		bio_add_virt_nofail(bio, base, size);
>  }
>  
>  int bch2_bio_alloc_pages(struct bio *bio, size_t size, gfp_t gfp_mask)
> -- 
> 2.34.1
>