Re: [PATCH RFC] btrfs: allow extent buffer helpers to skip cross-page handling

[David Sterba <dsterba@suse.cz>]

On Thu, Nov 23, 2023 at 06:31:41AM +1030, Qu Wenruo wrote:
> 
> 
> On 2023/11/23 00:16, David Sterba wrote:
> > On Thu, Nov 16, 2023 at 03:49:06PM +1030, Qu Wenruo wrote:
> >> --- a/fs/btrfs/disk-io.c
> >> +++ b/fs/btrfs/disk-io.c
> >> @@ -80,8 +80,16 @@ static void csum_tree_block(struct extent_buffer *buf, u8 *result)
> >>   	char *kaddr;
> >>   	int i;
> >>
> >> +	memset(result, 0, BTRFS_CSUM_SIZE);
> >>   	shash->tfm = fs_info->csum_shash;
> >>   	crypto_shash_init(shash);
> >> +
> >> +	if (buf->addr) {
> >> +		crypto_shash_digest(shash, buf->addr + offset_in_page(buf->start) + BTRFS_CSUM_SIZE,
> >> +				    buf->len - BTRFS_CSUM_SIZE, result);
> >> +		return;
> >> +	}
> >
> > This duplicates the address and size
> >> +
> >>   	kaddr = page_address(buf->pages[0]) + offset_in_page(buf->start);
> >>   	crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE,
> >>   			    first_page_part - BTRFS_CSUM_SIZE);
> >> @@ -90,7 +98,6 @@ static void csum_tree_block(struct extent_buffer *buf, u8 *result)
> >>   		kaddr = page_address(buf->pages[i]);
> >>   		crypto_shash_update(shash, kaddr, PAGE_SIZE);
> >>   	}
> >> -	memset(result, 0, BTRFS_CSUM_SIZE);
> >>   	crypto_shash_final(shash, result);
> >
> > I'd like to have only one code doing the crypto_shash_ calls, so I'm
> > suggesting this as the final code (the diff is not clear);
> 
> This looks good to me, mind to update it inside your branch?

Thanks, yes I'll update it. As it's not a completely trivial change I'd
like to get the confirmation first.