On Mon, Jan 22, 2018 at 08:28:54PM -0700, Jens Axboe wrote: > On 1/22/18 8:18 PM, Goldwyn Rodrigues wrote: > >> that their application was "already broken". I'd hate for a kernel > >> upgrade to break them. > >> > >> I do wish we could make the change, and maybe we can. But it probably > >> needs some safe guard proc entry to toggle the behavior, something we > >> can drop in a few years when we're confident it won't break real > >> applications. > > > > Assuming we call it /proc/sys/fs/dio_short_writes(better names/paths?), > > should it be enabled or disabled by default? > > I'd enable it by default, if not, you are never going to be able to > remove it because you'll have no confidence that anyone actually flipped > the switch and ran with it enabled. The point of having it there and on > by default would be that if something does break, people have the option > of turning it off and restoring the previous behavior, without having to > change the kernel. I think it's an opt-in prctl that's something like PRCTL_SHORT_WRITES_ALLOWED.
