Re: Partitions?

[Kent Overstreet <koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.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?