On Fri, Feb 19, 2021 at 04:55:06PM +0100, Miklos Szeredi wrote: > On Fri, Feb 19, 2021 at 3:34 PM Vivek Goyal <[email protected]> wrote: > > > > On Fri, Feb 19, 2021 at 11:50:54AM +0000, Luis Henriques wrote: > > > Vivek Goyal <[email protected]> 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.
Hi Miklos, Ok, this sounds reasonable. I am running some quick tests and if I don't notice any serious performance regression, I will respin my patch. > Having an option to disable acls still makes sense, > but it's an optional plus. Agreed. If there are no serious negative performance issues with enabling ACL, then an option to disable is an optional plus. May be I will drop this for now and add this when somebody needs an option to disable ACL. Thanks Vivek
