Re: [RFC PATCH 0/4] Persistent device name using alias name

Greg KH
2011-07-08T19:58:56Z

On Fri, Jul 08, 2011 at 09:45:01PM +0200, Karel Zak wrote:
> On Fri, Jul 08, 2011 at 05:45:47PM +0900, Nao Nishijima wrote:
> > This patch series provides an "alias name" of the disk into kernel and procfs
> > messages. The user can assign a preferred name to an alias name of the device.
> >
> > Based on previous discussion (*), I changed patches as follows
> > - This is "alias name"
> > - An "alias name" is stored in gendisk struct
> > - Add document to Documentation/ABI/testing/sysfs-block
> > - When the user changes an "alias name", kernel notifies udev
> >
> > (*) http://marc.info/?l=linux-scsi&m=130812625531219&w=2
> >
>
> [...]
>
> > [localhost]# cat /proc/partitions
> > major minor #blocks name
> >
> > 8 0 12582912 foo
> > 8 1 12582878 foo1
> > 8 0 8388608 sdb
> > 8 1 512000 sdb1
> > 8 2 7875584 sdb2
>
> If there is not /dev/foo and /sys/block/foo then the patch introduces
> a REGRESSION.
>
> The names from /proc/partitions are used in many applications
> (libblkid, fdisk, ...) for many many years. The applications will not
> work as expected.
>
> It's crazy to assume that all the applications will be improved to
> translate the "pretty name" from /proc/partitions by /sys/block/<maj>:<min>.
>
> Note, it's pretty naive to expect that people will use the pretty
> names for printk()/dmesg only. I'm absolutely sure that it's will be
> expected (by end-users) in /etc/fstab, mount, df, fdisk, ...
>
> It's will be necessary to modify all these utils.

And it would be even easier, to just modify the utilities in the first
place to handle the symlink names in /dev/disk that are there today, and
leave the kernel alone.

With the above information you provided, I don't see how we can accept
this patch at all as it will break existing userspace utilities which is
not allowed.

thanks,

greg k-h