[ Fixed subject:
Really I meant 16 minors per device, not per-major; major hasn't changed.]
On Sun, 23 Oct 2016, Eric Wheeler wrote:
> On Fri, 14 Oct 2016, Wido den Hollander wrote:
> > > Op 29 september 2016 om 19:11 schreef Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>:
> > > Le Thu, 29 Sep 2016 18:52:14 +0200 (CEST)
> > > Wido den Hollander <wido@xxxxxxxx> écrivait:
> > > > > I agree, but usually you wouldn't partition an MD-RAID either, would
> > > > > you? OSDs are still holding (so far) ordinary filesystems locally
> > > > > mounted on the nodes (except for BlueStore AFAIK).
> > > > I have partitioned MD-RAID before, works just fine.
> > >
> > > Yes, sure. It just doesn't feel right, my grey-bearded Unix instinct
> > > tingles :)
> > >
> > > > The question still remains, can bcache be patched that it allocates
> > > > the right minor in the kernel so that it allows for partitions.
> > >
> > > Even looks easy... As Sam Yaple made a patch.
> > >
> > > > I'm not a kernel nor bcache developer, just looking for somebody who
> > > > would be willing to do this. Happy to assist, support and test!
> > >
> > > Well if I have some time I may give it a try next week :)
> > >
> >
> > I was wondering if you were able to take a look at this?
>
> Hi Wido,
>
> See below and please test. It works for me, but I've not done any more
> than create a partition and verify that it was detected. Use-case
> opinions aside, some may or may not wish to use partitions atop of bcache.
> (If you do, just make sure they are aligned correctly!).
>
> I'll add your tested-by and request a pull for v4.9 unless someone has
> good reason to implement this differently.
>
> Kent, is there any reason to change this implementation?
>
> --
> Eric Wheeler
>
>
>
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 849ad44..6e53afd 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -58,6 +58,7 @@
> struct workqueue_struct *bcache_wq;
>
> #define BTREE_MAX_PAGES (256 * 1024 / PAGE_SIZE)
> +#define BCACHE_MINORS 16 /* partition support */
>
> /* Superblock */
>
> @@ -783,8 +784,10 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size,
> if (minor < 0)
> return minor;
>
> + minor *= BCACHE_MINORS;
> +
> if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
> - !(d->disk = alloc_disk(1))) {
> + !(d->disk = alloc_disk(BCACHE_MINORS))) {
> ida_simple_remove(&bcache_minor, minor);
> return -ENOMEM;
> }
