On Wed, Nov 28, 2018 at 04:33:03PM +1100, Dave Chinner wrote: > - how does propagation through stacked layers work? The only way it works is by each layering driving it. Thus my recommendation above bilding on your earlier one to use an index that is filled by the driver at I/O completion time. E.g. bio_init: bi_leg = -1 raid1: submit bio to lower driver raid 1 completion: set bi_leg to 0 or 1 Now if we want to allow stacking we need to save/restore bi_leg before submitting to the underlying device. Which is possible, but quite a bit of work in the drivers. > - is it generic/abstract enough to be able to work with > RAID5/6 to trigger verification/recovery from the parity > information in the stripe? If we get the non -1 bi_leg for paritity raid this is an inidicator that parity rebuild needs to happen. For multi-parity setups we could also use different levels there.
