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From: Kay Sievers <kay.sievers@vrfy.org>
To: Ric Wheeler <rwheeler@redhat.com>
Cc: Lennart Poettering <lennart@poettering.net>,
	Josef Bacik <josef@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] Btrfs: add a disk info ioctl to get the disks attached to a filesystem
Date: Wed, 29 Sep 2010 10:04:31 +0200	[thread overview]
Message-ID: <AANLkTimHmbVbScgDHsb8f=ts0QKr-+pwNm=YY4sG+bz1@mail.gmail.com> (raw)
In-Reply-To: <4CA2E9CD.5090700@redhat.com>

On Wed, Sep 29, 2010 at 09:25, Ric Wheeler <rwheeler@redhat.com> wrote:

> Second question is why is checking in /sys a big deal, would =C2=A0yo=
u prefer an
> interface like we did for alignment in libblkid?

It's about knowing what's behind the 'nodev' major =3D=3D 0 of a btrfs
mount. There is no way to get that from /sys or anywhere else at the
moment.

Usually filesystems backed by a disk have the dev_t of the device, or
the fake block devices like md/dm/raid have their own major and the
slaves/ directory pointing to the devices.

This is not only about readahead, it's every other tool, that needs to
know what kind of disks are behind a btrfs 'nodev' major =3D=3D 0 mount=
=2E

Kay
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  reply	other threads:[~2010-09-29  8:04 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-28 20:53 [PATCH] Btrfs: add a disk info ioctl to get the disks attached to a filesystem Josef Bacik
2010-09-28 22:28 ` Goffredo Baroncelli
2010-09-29  0:24   ` Josef Bacik
2010-09-28 23:25 ` Christoph Hellwig
2010-09-29  0:08   ` Josef Bacik
2010-09-29  0:19     ` Lennart Poettering
2010-09-29  7:25       ` Ric Wheeler
2010-09-29  8:04         ` Kay Sievers [this message]
2010-09-29 23:43           ` Christoph Hellwig
2010-09-30  0:32             ` Josef Bacik
2010-09-30  7:43             ` Kay Sievers
2010-09-30 12:38               ` Josef Bacik
2010-09-30 13:47               ` Andi Kleen
2010-09-30 19:48             ` Josef Bacik
2010-09-30 19:59               ` Kay Sievers
2010-09-30 20:37                 ` Lennart Poettering
2010-09-29 11:59         ` Lennart Poettering
2010-09-29 12:08           ` Ric Wheeler
2010-09-29 12:19   ` Kay Sievers

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