From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: Partitions? Date: Fri, 2 Nov 2012 08:33:35 -0700 Message-ID: <20121102153335.GD14917@google.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: James Sefton Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org On Fri, Nov 02, 2012 at 03:24:13AM +0000, James Sefton wrote: > Hi, > > I have got my /dev/bcache0 device showing up and attached the cache. > > I then used fdisk to add a single partition to it but it gave an error on exit: > > WARNING: Re-reading the partition table failed with error 22: Invalid argument. > The kernel still uses the old table. The new table will be used at > the next reboot or after you run partprobe(8) or kpartx(8) > > > I have had this before quite a bit and often have to run partprobe after leaving > fdisk for the partition table to be read and partitions populated in /dev. > > However, when running partprobe (or partprobe /dev/bcache0) I get the following: > > Error: Error informing the kernel about modifications to partition > /dev/bcache0p1 -- Invalid argument. This means Linux won't know about any > changes you made to /dev/bcache0p1 until you reboot -- so you shouldn't mount it > or use it in any way before rebooting. > Error: Failed to add partition 1 (Invalid argument) > > > I checked /dev and confirmed that bcache0p1 was not present. > > > What did I do wrong? Oh, that's nothing you did... the bcache code is just creating an unpartitionalable block device. I suppose there's no real reason for that... I _think_ all you'd need to change is one line, in drivers/md/bcache/super.c: if you search through the file, you'll find a call to alloc_disk(1) somewhere - change that to alloc_disk(16). Want to try that and let me know if it works?