From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kay Sievers 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 Message-ID: References: <1285707196-16268-1-git-send-email-josef@redhat.com> <20100928232513.GA20629@infradead.org> <20100929000809.GC32420@dhcp231-156.rdu.redhat.com> <20100929001954.GA9182@tango.0pointer.de> <4CA2E9CD.5090700@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Lennart Poettering , Josef Bacik , Christoph Hellwig , linux-btrfs@vger.kernel.org To: Ric Wheeler Return-path: In-Reply-To: <4CA2E9CD.5090700@redhat.com> List-ID: On Wed, Sep 29, 2010 at 09:25, Ric Wheeler 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 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html