From: Christoph Hellwig <hch@lst.de>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Yury Kamenev <damtev@yandex-team.ru>,
mst@redhat.com, jasowang@redhat.com, pbonzini@redhat.com,
axboe@kernel.dk, virtualization@lists.linux-foundation.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mmc@vger.kernel.org, Lauri Kasanen <cand@gmx.com>
Subject: Re: [PATCH 1/1] virtio: disable partitions scanning for no partitions block
Date: Mon, 24 May 2021 16:56:54 +0200 [thread overview]
Message-ID: <20210524145654.GA2632@lst.de> (raw)
In-Reply-To: <YKu4Qovv1KMplifY@stefanha-x1.localdomain>
On Mon, May 24, 2021 at 03:29:22PM +0100, Stefan Hajnoczi wrote:
> GENHD_FL_NO_PART_SCAN is not used much in other drivers. This makes me
> wonder if the same use case is addressed through other means with SCSI,
> NVMe, etc devices. Maybe Christoph or Jens can weigh in on whether
> adding a bit to disable partition scanning for a virtio-blk fits into
> the big picture?
>
> Is your goal to avoid accidentally detecting partitions because it's
> confusing when that happens?
I'm really confused what the use case is here. GENHD_FL_NO_PART_SCAN
has four users:
- the block core setting it for hidden devices, for which the concept
of paritions doesn't make sense. Looking back this should have never
used GENHD_FL_NO_PART_SCAN, and instead the partition scanning code
should just check GENHD_FL_HIDDEN as well.
- mmc uses it for boot partitions and rpmb. I'm not even sure how
these can be exposed as block devices as they don't require block
granularity access IIRC, but if the allow block layer access there
is no reason to ever set these flags.
- loop is a bit of a mess. IIRC the story is that originally the
loop device did not support partitions, then in 2008 support for
partitions was added by partitioning the minor number space, and
then in 2011 support for partitions without that parameter was
added using a new flag in the loop device creation ioctl that uses
the extended dev_t space added since. But even that might be
something we can handled without that flag without breaking the
userspace ABI
- m64card sets it for no good reason at all
In other words: in a perfect would GENHD_FL_NO_PART_SCAN would not
exist, and it certainly should not be added to a new driver, never
mind a protocol.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Yury Kamenev <damtev@yandex-team.ru>,
axboe@kernel.dk, mst@redhat.com, linux-mmc@vger.kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-block@vger.kernel.org, pbonzini@redhat.com,
Lauri Kasanen <cand@gmx.com>
Subject: Re: [PATCH 1/1] virtio: disable partitions scanning for no partitions block
Date: Mon, 24 May 2021 16:56:54 +0200 [thread overview]
Message-ID: <20210524145654.GA2632@lst.de> (raw)
In-Reply-To: <YKu4Qovv1KMplifY@stefanha-x1.localdomain>
On Mon, May 24, 2021 at 03:29:22PM +0100, Stefan Hajnoczi wrote:
> GENHD_FL_NO_PART_SCAN is not used much in other drivers. This makes me
> wonder if the same use case is addressed through other means with SCSI,
> NVMe, etc devices. Maybe Christoph or Jens can weigh in on whether
> adding a bit to disable partition scanning for a virtio-blk fits into
> the big picture?
>
> Is your goal to avoid accidentally detecting partitions because it's
> confusing when that happens?
I'm really confused what the use case is here. GENHD_FL_NO_PART_SCAN
has four users:
- the block core setting it for hidden devices, for which the concept
of paritions doesn't make sense. Looking back this should have never
used GENHD_FL_NO_PART_SCAN, and instead the partition scanning code
should just check GENHD_FL_HIDDEN as well.
- mmc uses it for boot partitions and rpmb. I'm not even sure how
these can be exposed as block devices as they don't require block
granularity access IIRC, but if the allow block layer access there
is no reason to ever set these flags.
- loop is a bit of a mess. IIRC the story is that originally the
loop device did not support partitions, then in 2008 support for
partitions was added by partitioning the minor number space, and
then in 2011 support for partitions without that parameter was
added using a new flag in the loop device creation ioctl that uses
the extended dev_t space added since. But even that might be
something we can handled without that flag without breaking the
userspace ABI
- m64card sets it for no good reason at all
In other words: in a perfect would GENHD_FL_NO_PART_SCAN would not
exist, and it certainly should not be added to a new driver, never
mind a protocol.
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next prev parent reply other threads:[~2021-05-24 15:00 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 13:39 [PATCH 0/1] virtio: disable partitions scanning for no partitions block Yury Kamenev
2021-05-20 13:39 ` [PATCH 1/1] " Yury Kamenev
2021-05-24 14:29 ` Stefan Hajnoczi
2021-05-24 14:29 ` Stefan Hajnoczi
2021-05-24 14:56 ` Christoph Hellwig [this message]
2021-05-24 14:56 ` Christoph Hellwig
2021-05-24 16:25 ` Ulf Hansson
2021-05-24 16:25 ` Ulf Hansson
[not found] ` <90021621883891@mail.yandex-team.ru>
2021-05-24 19:41 ` Paolo Bonzini
2021-05-24 19:41 ` Paolo Bonzini
2021-05-25 12:00 ` Iurii Kamenev
-- strict thread matches above, loose matches on Subject: below --
2021-07-15 9:47 [PATCH 0/1] " Yury Kamenev
2021-07-15 9:47 ` [PATCH 1/1] " Yury Kamenev
2021-07-15 11:22 ` Paolo Bonzini
2021-07-15 11:22 ` Paolo Bonzini
2021-07-16 1:09 ` kernel test robot
2021-07-16 1:09 ` kernel test robot
2021-07-16 1:09 ` kernel test robot
2021-07-16 2:57 ` Jason Wang
2021-07-16 2:57 ` Jason Wang
2021-05-20 13:36 [PATCH 0/1] " Yury Kamenev
2021-05-20 13:36 ` [PATCH 1/1] " Yury Kamenev
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