Re: [PATCH 10/15] btrfs: add a btrfs_map_bio_wait helper

From: Christoph Hellwig <hch@lst.de>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Christoph Hellwig <hch@lst.de>, Chris Mason <clm@fb.com>,
	Josef Bacik <josef@toxicpanda.com>,
	David Sterba <dsterba@suse.com>, Qu Wenruo <wqu@suse.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 10/15] btrfs: add a btrfs_map_bio_wait helper
Date: Wed, 18 May 2022 10:47:42 +0200	[thread overview]
Message-ID: <20220518084742.GE6933@lst.de> (raw)
In-Reply-To: <35c12a78-fe5d-c683-58c7-d600e8f7ce14@gmx.com>

On Wed, May 18, 2022 at 06:26:08AM +0800, Qu Wenruo wrote:
>
>
> On 2022/5/17 22:50, Christoph Hellwig wrote:
>> This helpers works like submit_bio_wait, but goes through the btrfs bio
>> mapping using btrfs_map_bio.
>
> I hate the naming of btrfs_map_bio(), which should be
> btrfs_map_and_submit_bio(), but I also totally understand my poor naming
> scheme is even worse for most cases.
>
> Maybe we can add the "submit" part into the new function?

I was tempted to rename btrfs_map_bio to just btrfs_submit_bio a
few times, but always had more important things to do first.  But
either way this helper should match the naming of the main async
function.

>> +	DECLARE_COMPLETION_ONSTACK(done);
>> +	blk_status_t ret;
>
> Is there any lockdep assert to make sure we're in wq context?

No.  You can build some asserts manually, but wait_for_completion will
already do that, so I'm not sure what the benefit would be.