Re: [PATCH 12/32] btrfs: disk-io: extract the extent buffer verification from btrfs_validate_metadata_buffer()

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2020/11/7 上午3:03, David Sterba wrote:
> On Thu, Nov 05, 2020 at 03:57:14PM +0200, Nikolay Borisov wrote:
>>> +int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, u64 phy_offset,
>>> +				   struct page *page, u64 start, u64 end,
>>> +				   int mirror)
>>> +{
>>> +	struct extent_buffer *eb;
>>> +	int ret = 0;
>>> +	int reads_done;
>>> +
>>> +	if (!page->private)
>>> +		goto out;
>>> +
>>
>> nit:I think this is redundant since metadata pages always have their eb
>> attached at ->private.
>
> We could have an assert here instead.

Yes, we can do that for now.

But later patches, like "implement subpage metadata read and its endio
function" would make subpage page->private initialized to 0 as we no
longer rely on page->private any more.

This means we will add the assert() just for several commits, then
remove it again.

Thanks,
Qu
>
>>> +	eb = (struct extent_buffer *)page->private;
>>
>> If the above check is removed then this line can be moved right next to
>> eb's definition.
>>
>> <snip>