On Sat, Dec 13, 2014 at 09:06:45AM -0500, Jeff Layton wrote: > On Fri, 12 Dec 2014 16:59:52 +0000 > Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > > On Fri, Dec 12, 2014 at 06:54:08AM -0500, Jeff Layton wrote: > > > > > > Umm... I would be very surprised if it turned out to be a problem. > > > > nfsd really doesn't give a fuck about its cwd and root - not in the > > > > thread side of things. And (un)exporting is (a) not on a hot path > > > > and (b) not done from a kernel thread anyway. fh_to_dentry and friends > > > > doesn't care about root/cwd, etc. > > > > > > > > I don't see anything that could cause that kind of issues. > > > > > > I like the change overall -- it would certainly make my patch series > > > simpler, but what about pathwalking? We do take the fs->lock in > > > unlazy_walk. Is it possible we'd end up with more contention there? > > > > That would take a pathname lookup in kernel thread side of nfsd that > > * isn't single-component > > * isn't LOOKUP_ROOT one (i.e. vfs_path_lookup() or file_open_root()) > > and I would really hope we don't have such things. Any such a beast would > > allow probing the tree layout outside of what we export, to start with... > > > > AFAICS, we really don't have anything of that sort. Note that e.g. > > lookup_one_len() doesn't go anywhere near ->fs->lock... > > Ahh right. Ok, then I don't see any issue with this so far. Maybe worth > letting it stew in -next once -rc1 ships? Thanks! FWIW, right now I think that out of those 3 commits #1 (separating PID 1 from init_fs + making all kernel threads get umask 0) and #3 (assorted crapectomy in lustre, getting rid of odd games with fs_struct there) are OK for mainline, with #2 (removal of unshare_fs_struct()) being -next fodder, to see if we get anything like unexpected contention, etc. -- 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
