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From: Christoph Hellwig <hch@infradead.org>
To: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-bcachefs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 05/20] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset
Date: Wed, 2 Aug 2023 04:47:18 -0700	[thread overview]
Message-ID: <ZMpCRpNyt0EJpg9G@infradead.org> (raw)
In-Reply-To: <20230801190450.3lbr2hjdi7t52anx@moria.home.lan>

On Tue, Aug 01, 2023 at 03:04:50PM -0400, Kent Overstreet wrote:
> > Because blk-cgroup not only works at the lowest level in the stack,
> > but also for stackable block devices.  It's not a design decision I
> > particularly agree with, but it's been there forever.
> 
> You're setting the association only to the highest block device in the
> stack - how on earth is it supposed to work with anything lower?

Hey, ask the cgroup folks as they come up with it.  I'm not going to
defend the logic here.

> And looking at bio_associate_blkg(), this code looks completely broken.
> It's checking bio->bi_blkg, but that's just been set to NULL in
> bio_init().

It's checking bi_blkg because it can also be called from bio_set_dev.

> And this is your code, so I think you need to go over this again.

It's "my code" in the sene of that I did one big round of unwinding
the even bigger mess that was there.  There is another few rounds needed
for the code to vaguely make sense.

  reply	other threads:[~2023-08-02 11:47 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230712211115.2174650-1-kent.overstreet@linux.dev>
2023-07-12 21:10 ` [PATCH 04/20] block: Add some exports for bcachefs Kent Overstreet
2023-07-24 17:31   ` Christoph Hellwig
2023-07-25  3:00     ` Kent Overstreet
2023-07-26 13:20       ` Christoph Hellwig
2023-08-01 18:59         ` Kent Overstreet
2023-07-25  2:59   ` Matthew Wilcox
2023-07-12 21:11 ` [PATCH 05/20] block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset Kent Overstreet
2023-07-24 17:34   ` Christoph Hellwig
2023-07-25  2:43     ` Kent Overstreet
2023-07-26 13:23       ` Christoph Hellwig
2023-08-01 19:04         ` Kent Overstreet
2023-08-02 11:47           ` Christoph Hellwig [this message]
2023-08-02 16:44             ` Kent Overstreet
2023-07-12 21:11 ` [PATCH 06/20] block: Bring back zero_fill_bio_iter Kent Overstreet
2023-07-24 17:35   ` Christoph Hellwig
2023-07-25  2:45     ` Kent Overstreet
2023-07-26 13:21       ` Christoph Hellwig
2023-08-01 19:05         ` Kent Overstreet

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