On Fri, Mar 9, 2012 at 10:43 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > Il 09/03/2012 11:31, Stefan Hajnoczi ha scritto: >>> > +#ifdef FALLOC_FL_PUNCH_HOLE >>> > + retval = fallocate(s->fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, >>> > + sector_num << 9, (int64_t)nb_sectors << 9); >> I'm concerned about introducing blocking syscalls in coroutine code >> paths. This needs to be done asynchronously. > > Right; it is no worse than what is already there, except that XFS could > use paio_ioctl. Alternatives are:
It is worse in the sense that if you make this feature more widely available then it deserves a production-quality implementation. > 1) require a new-enough kernel and only use fallocate; return a NULL > aiocb if !has_discard and convert it to ENOTSUP. > > 2) extract now from my threads branch the work to generalize > posix-aio-compat into a more flexible threadpool, and move the AIO code > back to block/raw-posix.c. 3) Add discard to posix-aio-compat.c as an AIO request? Stefan
