Re: [PATCH v3 1/6] block: add disk sequence number

[Matteo Croce]

On Wed, Jun 23, 2021 at 1:49 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Wed, Jun 23, 2021 at 12:58:53PM +0200, Matteo Croce wrote:
> > +void inc_diskseq(struct gendisk *disk)
> > +{
> > +     static atomic64_t diskseq;
>
> Please don't hide file scope variables in functions.
>

I just didn't want to clobber that file namespace, as that is the only
point where it's used.

> Can you explain a little more why we need a global sequence count vs
> a per-disk one here?

The point of the whole series is to have an unique sequence number for
all the disks.
Events can arrive to the userspace delayed or out-of-order, so this
helps to correlate events to the disk.
It might seem strange, but there isn't a way to do this yet, so I come
up with a global, monotonically incrementing number.

-- 
per aspera ad upstream