On Thu, May 28, 2020 at 10:58:31PM +0200, Hannes Reinecke wrote: > On 5/28/20 8:54 PM, Matthew Wilcox wrote: > > On Thu, May 28, 2020 at 01:50:02PM -0400, Douglas Gilbert wrote: > > > On 2020-05-28 12:36 p.m., Hannes Reinecke wrote: > > > > Use xarray for device lookup by target. LUNs below 256 are linear, > > > > and can be used directly as the index into the xarray. > > > > LUNs above 256 have a distinct LUN format, and are not necessarily > > > > linear. They'll be stored in indices above 256 in the xarray, with > > > > the next free index in the xarray. > > > > I don't understand why you think this is an improvement over just > > using an allocating XArray for all LUNs. It seems like more code, > > and doesn't actually save you any storage space ... ? > > > The LUN range is 64 bit. > I was under the impression that xarray can only handle up to unsigned long; > which probably would work for 64bit systems, but there _are_ users running > on 32 bit, and they get patently unhappy when we have to tell them 'sorry, > not for you'. I meant just use xa_alloc() for everything instead of using xa_insert for 0-255.
