Miklos Szeredi <mik...@szeredi.hu> writes: > On Fri, Feb 19, 2021 at 3:34 PM Vivek Goyal <vgo...@redhat.com> wrote: >> >> On Fri, Feb 19, 2021 at 11:50:54AM +0000, Luis Henriques wrote: >> > Vivek Goyal <vgo...@redhat.com> writes: >> > >> > > Hi, >> > > >> > > This is V2 of the patches. Changes since v1 are. >> > > >> > > - Rebased on top of latest master. >> > > - Took care of Miklos's comments to block acl xattrs if user >> > > explicitly disabled posix acl. >> > > >> > > Luis Henriques reported that fstest generic/099 fails with virtiofs. >> > > Little debugging showed that we don't enable acl support. So this >> > > patch series provides option to enable/disable posix acl support. By >> > > default it is disabled. >> > > >> > > I have run blogbench and pjdfstests with posix acl enabled and >> > > things work fine. >> > > >> > > Luis, can you please apply these patches, and run virtiofsd with >> > > "-o posix_acl" and see if it fixes the failure you are seeing. I >> > > ran the steps you provided manually and it fixes the issue for >> > > me. >> > >> > Sorry for the delay. I've finally tested these patches and they indeed >> > fix the problem I reported. My only question about this fix is why is >> > this option not enabled by default, since this is the documented behavior >> > in acl(5) and umask(2)? In fact, why is this an option at all? >> >> You mean why to not enable acl by default? >> >> I am concerned about performance drop this can lead to because extra >> GETXATTR(system.posix_acl_*) messages which will trigger if acls are enabled. >> And not all users might require these. That's why I preferred to not enable >> acl by default. Those who need it can enable it explicitly. >> >> Another example is xattr support. Due to performance concerns, we don't >> enable xattrs by default either. > > Actually generic xattr is much worse, since there's no caching for > them currently, as opposed to posix acls, which are cached both when > positive and negative. > > If we enable ACL by default in case xattrs are enabled, we should be > safe, I think. Having an option to disable acls still makes sense, > but it's an optional plus.
Great, thanks for clarifying that the reason for having these options is really for performance. Anyway, thanks a lot for looking at this and fixing it. Cheers, -- Luis
