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From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Matteo Croce <mcroce@linux.microsoft.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Lennart Poettering <lennart@poettering.net>,
	Luca Boccassi <bluca@debian.org>, Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Damien Le Moal <damien.lemoal@wdc.com>, Tejun Heo <tj@kernel.org>,
	Javier Gonz?lez <javier@javigon.com>,
	Niklas Cassel <niklas.cassel@wdc.com>,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>,
	Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH -next 1/5] block: add disk sequence number
Date: Tue, 16 Mar 2021 14:13:26 +0000
Message-ID: <20210316141326.GA37773@infradead.org> (raw)
In-Reply-To: <20210315201824.GB2577561@casper.infradead.org>

On Mon, Mar 15, 2021 at 08:18:24PM +0000, Matthew Wilcox wrote:
> On Mon, Mar 15, 2021 at 09:02:38PM +0100, Matteo Croce wrote:
> > From: Matteo Croce <mcroce@microsoft.com>
> > 
> > Add a sequence number to the disk devices. This number is put in the
> > uevent so userspace can correlate events when a driver reuses a device,
> > like the loop one.
> 
> Should this be documented as monotonically increasing?  I think this
> is actually a media identifier.  Consider (if you will) a floppy disc.
> Back when such things were common, it was possible with personal computers
> of the era to have multiple floppy discs "in play" and be prompted to
> insert them as needed.  So shouldn't it be possible to support something
> similar here -- you're really removing the media from the loop device.
> With a monotonically increasing number, you're always destroying the
> media when you remove it, but in principle, it should be possible to
> reinsert the same media and have the same media identifier number.

And we have some decent infrastructure related to media changes,
grep for disk_events.  I think this needs to plug into that
infrastructure instead of duplicating it.

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-15 20:02 [PATCH -next 0/5] block: add a sequence number to disks Matteo Croce
2021-03-15 20:02 ` [PATCH -next 1/5] block: add disk sequence number Matteo Croce
2021-03-15 20:18   ` Matthew Wilcox
2021-03-15 21:04     ` Matthew Wilcox
2021-03-15 21:32       ` Lennart Poettering
2021-03-25 17:29       ` Matteo Croce
2021-03-26  8:00         ` Hannes Reinecke
2021-03-25 20:58       ` Lennart Poettering
2021-03-16 14:13     ` Christoph Hellwig [this message]
2021-04-20 20:12       ` Lennart Poettering
2021-03-25 20:52     ` Lennart Poettering
2021-03-16  1:44   ` JeffleXu
2021-03-23 17:43     ` Matteo Croce
2021-03-15 20:02 ` [PATCH -next 2/5] block: add ioctl to read the " Matteo Croce
2021-03-15 20:13   ` Matthew Wilcox
2021-03-15 20:17     ` Damien Le Moal
2021-03-15 20:34     ` Matteo Croce
2021-03-15 20:02 ` [PATCH -next 3/5] block: refactor sysfs code Matteo Croce
2021-03-15 20:02 ` [PATCH -next 4/5] block: export diskseq in sysfs Matteo Croce
2021-03-15 20:02 ` [PATCH -next 5/5] loop: increment sequence number Matteo Croce

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