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From: Christoph Hellwig <hch@infradead.org>
To: Matteo Croce <mcroce@linux.microsoft.com>
Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org,
	Lennart Poettering <lennart@poettering.net>,
	Luca Boccassi <bluca@debian.org>,
	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>,
	Matthew Wilcox <willy@infradead.org>,
	Christoph Hellwig <hch@infradead.org>,
	JeffleXu <jefflexu@linux.alibaba.com>
Subject: Re: [PATCH v3 6/6] loop: increment sequence number
Date: Wed, 23 Jun 2021 12:57:52 +0100	[thread overview]
Message-ID: <YNMhwLMr7DiNdqC/@infradead.org> (raw)
In-Reply-To: <20210623105858.6978-7-mcroce@linux.microsoft.com>

On Wed, Jun 23, 2021 at 12:58:58PM +0200, Matteo Croce wrote:
> From: Matteo Croce <mcroce@microsoft.com>
> 
> On a very loaded system, if there are many events queued up from multiple
> attach/detach cycles, it's impossible to match them up with the
> LOOP_CONFIGURE or LOOP_SET_FD call, since we don't know where the position
> of our own association in the queue is[1].
> Not even an empty uevent queue is a reliable indication that we already
> received the uevent we were waiting for, since with multi-partition block
> devices each partition's event is queued asynchronously and might be
> delivered later.
> 
> Increment the disk sequence number when setting or changing the backing
> file, so the userspace knows which backing file generated the event:

Instead of manually incrementing the sequence here, can we make loop
generate the DISK_EVENT_MEDIA_CHANGE event on a backing device (aka
media) change?

  reply	other threads:[~2021-06-23 11:58 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 10:58 [PATCH v3 0/6] block: add a sequence number to disks Matteo Croce
2021-06-23 10:58 ` [PATCH v3 1/6] block: add disk sequence number Matteo Croce
2021-06-23 11:48   ` Christoph Hellwig
2021-06-23 13:10     ` Matteo Croce
2021-06-23 13:51       ` Lennart Poettering
2021-06-23 14:01         ` Hannes Reinecke
2021-06-23 14:07           ` Luca Boccassi
2021-06-23 14:21             ` Hannes Reinecke
2021-06-23 14:34               ` Luca Boccassi
2021-06-23 14:55               ` Lennart Poettering
2021-06-23 14:12           ` Lennart Poettering
2021-06-23 15:02             ` Hannes Reinecke
2021-06-23 15:34               ` Luca Boccassi
2021-06-23 15:48               ` Lennart Poettering
2021-06-23 14:28       ` Christoph Hellwig
2021-06-23 10:58 ` [PATCH v3 2/6] block: add ioctl to read the " Matteo Croce
2021-06-23 10:58 ` [PATCH v3 3/6] block: refactor sysfs code Matteo Croce
2021-06-23 11:52   ` Christoph Hellwig
2021-06-23 19:03     ` Matteo Croce
2021-06-24  6:12       ` Christoph Hellwig
2021-06-23 10:58 ` [PATCH v3 4/6] block: export diskseq in sysfs Matteo Croce
2021-06-23 10:58 ` [PATCH v3 5/6] block: increment sequence number Matteo Croce
2021-06-23 10:58 ` [PATCH v3 6/6] loop: " Matteo Croce
2021-06-23 11:57   ` Christoph Hellwig [this message]
2021-06-23 13:13     ` Luca Boccassi
2021-06-23 14:25       ` Christoph Hellwig
2021-06-23 15:29         ` Lennart Poettering
2021-06-24  6:11           ` Christoph Hellwig
2021-06-23 12:03 ` [PATCH v3 0/6] block: add a sequence number to disks Hannes Reinecke
2021-06-23 12:46   ` Luca Boccassi
2021-06-23 14:07   ` Lennart Poettering

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