On Sat, May 27, 2023 at 12:45 AM Dave Chinner <da...@fromorbit.com> wrote:
> On Fri, May 26, 2023 at 12:04:02PM +0100, Joe Thornber wrote: > > > 1) We have an api (ioctl, bio flag, whatever) that lets you > > reserve/guarantee a region: > > > > int reserve_region(dev, sector_t begin, sector_t end); > > A C-based interface is not sufficient because the layer that must do > provsioning is not guaranteed to be directly under the filesystem. > We must be able to propagate the request down to the layers that > need to provision storage, and that includes hardware devices. > > e.g. dm-thin would have to issue REQ_PROVISION on the LBA ranges it > allocates in it's backing device to guarantee that the provisioned > LBA range it allocates is also fully provisioned by the storage > below it.... > Fine, bio flag it is. > > > This api should be used minimally, eg, critical FS metadata only. > > > > Plan for having to support tens of GBs of provisioned space in > filesystems, not tens of MBs.... > Also fine. I think there's a 2-3 solid days of coding to fully implement > REQ_PROVISION support in XFS, including userspace tool support. > Maybe a couple of weeks more to flush the bugs out before it's > largely ready to go. > > So if there's buy in from the block layer and DM people for > REQ_PROVISION as described, then I'll definitely have XFS support > ready for you to test whenever dm-thinp is ready to go. > Great, this is what I wanted to hear. I guess we need an ack from the block guys and then I'll get started. - Joe
-- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
