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Date:   Tue, 10 Aug 2021 15:38:40 +0200
From:   Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Ian Pilcher <arequipeno@gmail.com>, hch@lst.de, axboe@kernel.dk,
        kernelnewbies@kernelnewbies.org, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, pavel@ucw.cz, pali@kernel.org,
        linux-leds@vger.kernel.org
Subject: Re: [RFC PATCH v2 00/10] Add configurable block device LED triggers
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On Tue, 10 Aug 2021 08:35:08 +0200
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Mon, Aug 09, 2021 at 06:50:44PM -0500, Ian Pilcher wrote:
> > On 8/9/21 5:43 PM, Marek Beh=C3=BAn wrote: =20
> > > I confess that I am not very familiar with internal blkdev API. =20
> >=20
> > It's mainly a matter of symbol visibility.  See this thread from a few
> > months ago:
> >=20
> >   https://www.spinics.net/lists/linux-leds/msg18244.html
> >=20
> > Now ... my code currently lives in block/, so there isn't actually
> > anything technically preventing it from iterating through the block
> > devices.
> >=20
> > The reactions to Enzo's patch (which you can see in that thread) make me
> > think that anything that iterates through all block devices is likely to
> > be rejected, but maybe I'm reading too much into it.
> >=20
> >=20
> > Greg / Christoph -
> >=20
> > (As you were the people who expressed disapproval of Enzo's patch to
> > export block_class and disk_type ...)
> >=20
> > Can you weigh in on the acceptability of iterating through the block
> > devices (searching by name) from LED trigger code within the block
> > subsystem (i.e. no new symbols would need to be exported)?
> >=20
> > This would allow the trigger to implement the sysfs API that Marek and
> > Pavel want. =20
>=20
> No idea, let's see the change first, we can never promise anything :)

Hi Greg,

Can't we use blkdev_get_by_path() (or blk_lookup_devt() with
blkdev_get_by_dev())?
This would open the block device and return a struct block_device *.
When the LED trigger is disabled, it would also have to release the
device.

Marek