On Fri, Aug 18, 2017 at 09:18:52AM +0200, Hannes Reinecke wrote: > On 08/18/2017 08:15 AM, Omar Sandoval wrote: > > From: Omar Sandoval <osandov@xxxxxx> > > > > When I was writing a test for the new loop device block size > > functionality, I realized that the interface is kind of dumb: > > > > - lo_init[0] is never filled in with the logical block size we > > previously set > > - lo_flags returned from LOOP_GET_STATUS will have LO_FLAGS_BLOCKSIZE > > set if we previously called LOOP_SET_STATUS with LO_FLAGS_BLOCKSIZE > > set, which doesn't really mean anything > > > > Instead, for LOOP_GET_STATUS, let's always fill in lo_init[0] and set > > the LO_FLAGS_BLOCKSIZE flag to indicate we support it. > > > > Signed-off-by: Omar Sandoval <osandov@xxxxxx> > > --- > > drivers/block/loop.c | 33 +++++++++++++++++---------------- > > 1 file changed, 17 insertions(+), 16 deletions(-) > > > Phew. 'Dumb interface'. > 'tis wasn't me who designed the interface; > Backwards compability are the watchwords here. > Personally, I would have loved to design a new interface. > > I've got quite some flak for daring to break existing interfaces, most > notably setting logical and physical blocksize per default (which I > would _love_ to have done, seeing that it really makes sense here). > But as this would change the behaviour I've gone through pains (and > several _years_ of iterations) to get this sorted. > > So if you design a blocktest for that ensure that > a) the sysfs attributes before and after the patch are _identical_ > b) the sysfs attributes will only change if the 'LO_FLAGS_BLOCKSIZE' > flag has been set > and > c) validate the written blocksizes; this is required to be able to > install bootloaders there > > This whole interface was designed such that you can prepare bootable > diskimages for S/390 DASDs, which use a native 4k blocksize. Hi, Hannes, Wasn't insulting you at all, the only part of the interface I'm complaining about is LOOP_GET_STATUS missing information :)
