Re: [PATCH] nbd: provide a way for userspace processes to identify device backends
From: Matteo Croce
Date: Wed May 26 2021 - 10:14:02 EST
On Wed, May 19, 2021 at 4:33 PM Matteo Croce <mcroce@xxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, May 18, 2021 at 9:52 AM Prasanna Kalever <pkalever@xxxxxxxxxx> wrote:
> > > BTW, loop has similar issue, and patch of 'block: add a sequence number to disks'
> > > is added for addressing this issue, what do you think of that generic
> > > approach wrt. this nbd's issue? such as used the exposed sysfs sequence number
> > > for addressing this issue?
> > >
> > > https://lore.kernel.org/linux-block/YH81n34d2G3C4Re+@gardel-login/#r
> > If I understand the changes and the background of the fix correctly, I
> > think with that fix author is trying to monotonically increase the seq
> > number and add it to the disk on every single device map/attach and
> > expose it through the sysfs, which will help the userspace processes
> > further to correlate events for particular and specific devices that
> > reuse the same loop device.
> Yes, but nothing prevents to use diskseq in nbd, and increase it on reconfigure.
> That would allow to detect if the device has been reconfigured.
> per aspera ad upstream
FYI: I just sent a v2 of the diskseq change
per aspera ad upstream