On Wed, Jun 07, 2023 at 12:42:11AM -0700, Christoph Hellwig wrote:
> > +++ b/block/genhd.c
> > @@ -1502,3 +1502,4 @@ void inc_diskseq(struct gendisk *disk)
> > {
> > disk->diskseq = atomic64_inc_return(&diskseq);
> > }
> > +EXPORT_SYMBOL(inc_diskseq);
>
> I really do not like exporting this as a lowlevel function. If we
> increment the sequence it should be part of a higher level operation.
Fair!
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -1205,6 +1205,12 @@ static void __loop_clr_fd(struct loop_device *lo, bool release)
> > if (!part_shift)
> > set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
> > mutex_lock(&lo->lo_mutex);
> > +
> > + /*
> > + * Increment the disk sequence number, so that userspace knows this
> > + * device now points to something else.
> > + */
> > + inc_diskseq(lo->lo_disk);
>
> And I'm not sure why we even need this. __loop_clr_fd
> already calls disk_force_media_change, which calls inc_diskseq.
> Why do we need an extra increment?
How does disk_force_media_change() call inc_diskseq()? I don’t see any
calls in the source code. I’m going to use systemtap to see if there is
an indirect call chain.
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
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