Partitions?

Partitions?

[James Sefton]

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?

Many thanks,

James

Re: Partitions?

[Kent Overstreet]

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?

RE: Partitions?

[James Sefton]

Awesome.   1 byte change to the source!

I now have bcache0p1 in /dev.
Not used it yet but so far it's looking good. :)

-----Original Message-----
From: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of Kent Overstreet
Sent: 02 November 2012 15:34
To: James Sefton
Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Partitions?

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?
--
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