On Thu, Sep 08, 2011 at 09:47:50PM -0700, Chuck Lever wrote: > > On Sep 8, 2011, at 12:21 PM, J. Bruce Fields wrote: > > > On Thu, Sep 08, 2011 at 12:03:49PM -0700, Chuck Lever wrote: > >> > >> On Sep 8, 2011, at 11:24 AM, J. Bruce Fields wrote: > >> > >>> On Thu, Sep 08, 2011 at 01:59:46PM -0400, bfields wrote: > >>>> On Fri, Sep 02, 2011 at 12:38:13PM -0400, Chuck Lever wrote: > >>>>> Sometime soon we are going to have easy-to-install user space FedFS > >>>>> components. Here are kernel patches needed to make server-side FedFS > >>>>> support work. Please consider these for the 3.2 kernel. > >>>>> > >>>>> The third patch introduces a potentially expensive check to see if > >>>>> a junction has been encountered during a mountpoint lookup. An object > >>>>> is a junction iff it has the requisite set of extended attributes. > >>>>> However, reading an extended attribute is expensive on some file > >>>>> systems. > >>>>> > >>>>> To mitigate the cost of this check, junctions always have their sticky > >>>>> bit set. The expensive extended attribute part of the junction test > >>>>> is done only if the sticky bit is present. > >>>>> > >>>>> Note that today junctions are directories, but someday symlinks might > >>>>> also act as junctions (for SMB2 support). And very few files have the > >>>>> sticky bit set. So we avoid doing a directory test here. > >>>>> > >>>>> Also, junctions ostensibly have all zero mode bits to hide their local > >>>>> contents. I don't think the kernel needs to be concerned about the > >>>>> permissions as long as the sticky bit is set. This allows some > >>>>> flexibility in how junctions are represented. However, Jeff thinks > >>>>> that having nfsd4_is_junction() also consider mode bits would make the > >>>>> expensive part of this test still less frequent. > >>>>> > >>>>> Any thoughts about this? > >>>> > >>>> Hm, right, a sticky bit set on a directory is a normal thing. I thought > >>>> Trond's original idea was to check for the sticky bit and not > >>>> executable? Which is a pointless combination so should be very rare. > >>>> > >>>> On a typical system maybe directories with the sticky bit are normally > >>>> somewhat rare, but that's a question of policy and there could be cases > >>>> where it's common. > >>> > >>> Except for that and the one gripe about an error return, it looks fine > >>> to me. > >> > >> Noted. I can repost these with requested fixes in a day or two. > >> > >>> Remind me where the corresponding userland code is? > >> > >> http://oss.oracle.com/projects/fedfs-utils > > > > I can find gitweb, but not a git url to clone from. > > Try > > git clone git://oss.oracle.com/git/cel/fedfs-utils.git Got it, thanks! (There should be some way to configure your gitweb installation so it includes that.) --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
