On Tue, Aug 16, 2016 at 10:59 PM, Seth Forshee <seth.forshee@xxxxxxxxxxxxx> wrote: > Hi Miklos, > > On Thu, Aug 04, 2016 at 02:11:20PM +0200, Miklos Szeredi wrote: > > <snip> > >> And again. >> >> I'm really wondering if it's simpler to just add an xattr parser to >> libfuse and do these at the filesystem level. That would simplify >> this patchset a lot: >> >> Reduce the scope to just permission checking, which is what we can do >> best and fastest in the kernel. And leave the rest to userspace. >> They don't have performance impact, but trying to push this into the >> kernel is just asking for trouble. > > I've been playing with this over the past couple of days, and I wanted > to get a little more feedback before I proceed. > > Things are pretty simple in the kernel if we just pass through the acl > xattrs, but either the kernel or libfuse will need to work out the > equivalent file mode when posix acls are written. I'm favoring libfuse > for this, since it's very straightforward once you're already parsing > the xattr and then we won't need to add a setattr+setxattr op. What we > will need is to refresh the mode in the kernel from userspace. > > Right now after a successful setxattr we call fuse_invalidate_attr(), > which should take care of that problem. I'm not sure the reasoning > behind doing this still applies though. According to > d331a415aef98717393dda0be69b7947da08eba3 it was added to force a refresh > of ctime, but later in 31f3267b4ba16b12fb9dd3b1953ea0f221cc2ab4 fuse was > changed to prefer ctime as maintained by the kernel, so it looks like > that invalidate (and the one in removexattr, maybe others?) could be > removed. > > If so, we could still keep it when setting posix acl xattrs, which would > be the simplest option. Otherwise we need to get the mode back from > userspace after the setxattr, either via a conditional outarg for > setxattr or by adding a new operation. > > What's your preference for all of this? Lets just keep the invalidate. My philosophy is to not optimize until someone actually complains about performance. And these invalidates are unlikely to be a problem anyway. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
