Re: [PATCH 2/3] btrfs: rename struct btrfs_io_bio to struct btrfs_logical_bio

[Nikolay Borisov <nborisov@suse.com>]

On 7.09.21 г. 10:42, Qu Wenruo wrote:
> In btrfs there are at least 4 types of different bios currently:
> 
> - btrfs_io_bio
>   It's used to specify IO for logical bytenr

Perhaps this structure needs to be turned into a btrfs_bio.

> 
> - btrfs_bio
>   It's real physical bio

It's not even that, because btrfs_bio itself is not submitted at all,
it's really some sort of a semaphore, which is used to signal all stripe
bios i.e those bios which are submitted to the actual devices have
completed. In that regard it's not even a bio per-se, more like an
io_context.

> 
> - compressed_bio
>   Only used for compressed read write.

This should be compressed_io_ctx or some such.

> 
> - btrfs_raid_bio
>   Only used by RAID56
> 
> The naming of btrfs_bio and btrfs_io_bio is just anti-human.
> 
> Rename btrfs_io_bio to btrfs_logical_bio, and all involved helpers to
> make clear at which layer the bio works.
> 
> Since we're here, also add extra comments on critical members like
> @mirror_num.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

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