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Date: Wed, 17 Apr 2024 18:10:21 +0200
From: Lennart Poettering <mzxreary@0pointer.de>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>,
	Linux regressions mailing list <regressions@lists.linux.dev>,
	linux-block@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>
Subject: Re: API break, sysfs "capability" file
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On Mi, 17.04.24 17:59, Christoph Hellwig (hch@lst.de) wrote:

> On Wed, Apr 17, 2024 at 05:48:16PM +0200, Lennart Poettering wrote:
> > Block devices with part scanning off are quite common after all,
> > i.e. "losetup" creates them by default like that, and partition block
> > devices themselves have no part scanning on and so on, hence we have
> > to be ablet to operate sanely with them.
>
> Maybe and ioctl to turn on partition scanning if it is currently disabled
> or return an error otherwise would be the better thing?  It would
> do the right thing for the most common loop case, and with a bit more
> work could do the right thing for those that more or less disable it
> graciously (ubiblock, drbd, zram) and would just fail for those who are
> so grotty old code and slow devices that we never want to do a partition
> scan (basically old floppy drivers and the Nintendo N64 cartridge driver)

Well, there are plenty of other block devices with part scanning off,
such as DM, including dm-crypt, dm-integrity and so on. And that's
certainly stuff we want to cover for this.

Lennart

--
Lennart Poettering, Berlin