Re: [PATCH 03/17] btrfs: remove the open-code to read disk-key

[Nikolay Borisov <nborisov@suse.com>]

On 8.09.20 г. 10:52 ч., Qu Wenruo wrote:
> There is some ancient code from the old days where we handle the
> disk_key read manually when the disk key is in one page.>
> But that's totally unnecessary, as we have read_extent_buffer() to
> handle everything.

I'd rephrase this to something like:

"generic_bin_search distinguishes between reading a key which doesn't
cross a page and one which does. However this distinction is not
necessary since read_extent_buffer handles both cases transparently.

Just use read_extent_buffer to streamline the code"


> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

> ---
>  fs/btrfs/ctree.c | 13 ++-----------
>  1 file changed, 2 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index cd1cd673bc0b..e204e1320745 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -1697,7 +1697,6 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
>  	}
>  
>  	while (low < high) {
> -		unsigned long oip;
>  		unsigned long offset;
>  		struct btrfs_disk_key *tmp;
>  		struct btrfs_disk_key unaligned;
> @@ -1705,17 +1704,9 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
>  
>  		mid = (low + high) / 2;
>  		offset = p + mid * item_size;
> -		oip = offset_in_page(offset);
>  
> -		if (oip + key_size <= PAGE_SIZE) {
> -			const unsigned long idx = offset >> PAGE_SHIFT;
> -			char *kaddr = page_address(eb->pages[idx]);
> -
> -			tmp = (struct btrfs_disk_key *)(kaddr + oip);
> -		} else {
> -			read_extent_buffer(eb, &unaligned, offset, key_size);
> -			tmp = &unaligned;
> -		}
> +		read_extent_buffer(eb, &unaligned, offset, key_size);
> +		tmp = &unaligned;
>  
>  		ret = comp_keys(tmp, key);
>  
>