Date: Sun, 26 Jan 2025 14:33:23 -0800 From: Rick Macklem <rick.macklem@gmail.com> To: Gleb Smirnoff <glebius@freebsd.org> Cc: current@freebsd.org, rmacklem@freebsd.org Subject: Re: HEADS UP: NFS changes coming into CURRENT early February Message-ID: <CAM5tNy5EBUj6k0%2BXw0TwetVR0xx0pp5i2G3WC9L4wFyEnnmDWw@mail.gmail.com> In-Reply-To: <CAM5tNy7APTu3HVqYoMzb1YCOC7QiFzaRq9NGtYFAJi_uOu094Q@mail.gmail.com> References: <Z5CP2WBdW_vbqzil@cell.glebi.us> <CAM5tNy7APTu3HVqYoMzb1YCOC7QiFzaRq9NGtYFAJi_uOu094Q@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, Jan 26, 2025 at 1:44=E2=80=AFPM Rick Macklem <rick.macklem@gmail.co= m> wrote: > > On Tue, Jan 21, 2025 at 10:27=E2=80=AFPM Gleb Smirnoff <glebius@freebsd.o= rg> wrote: > > > > CAUTION: This email originated from outside of the University of Guelph= . Do not click links or open attachments unless you recognize the sender an= d know the content is safe. If in doubt, forward suspicious emails to IThel= p@uoguelph.ca. > > > > > > Hi, > > > > TLDR version: > > users of NFS with Kerberos (e.g. running gssd(8)) as well as users of N= FS with > > TLS (e.g. running rpc.tlsclntd(8) or rpc.tlsservd(8)) as well as users = of > > network lock manager (e.g. having 'options NFSLOCKD' and running rpcbin= d(8)) > > are affected. You would need to recompile & reinstall both the world a= nd the > > kernel together. Of course this is what you'd normally do when you tra= ck > > FreeBSD CURRENT, but better be warned. I will post hashes of the speci= fic > > revisions that break API/ABI when they are pushed. > > > > Longer version: > > last year I tried to check-in a new implementation of unix(4) SOCK_STRE= AM and > > SOCK_SEQPACKET in d80a97def9a1, but was forced to back it out due to se= veral > > kernel side abusers of a unix(4) socket. The most difficult ones are t= he NFS > > related RPC services, that act as RPC clients talking to an RPC servers= in > > userland. Since it is impossible to fully emulate a userland process > > connection to a unix(4) socket they need to work with the socket intern= al > > structures bypassing all the normal KPIs and conventions. Of course th= ey > > didn't tolerate the new implementation that totally eliminated intermed= iate > > buffer on the sending side. > > > > While the original motivation for the upcoming changes is the fact that= I want > > to go forward with the new unix/stream and unix/seqpacket, I also tried= to make > > kernel to userland RPC better. You judge if I succeeded or not :) Here= are > > some highlights: > > > > - Code footprint both in kernel clients and in userland daemons is redu= ced. > > Example: gssd: 1 file changed, 5 insertions(+), 64 deletions(-) > > kgssapi: 1 file changed, 26 insertions(+), 78 deletions(-) > > 4 files changed, 1 insertion(+), 11 deletions(-) > > - You can easily see all RPC calls from kernel to userland with genl(1)= : > > # genl monitor rpcnl > > - The new transport is multithreaded in kernel by default, so kernel cl= ients > > can send a bunch of RPCs without any serialization and if the userlan= d > > figures out how to parallelize their execution, such parallelization = would > > happen. Note: new rpc.tlsservd(8) will use threads. > > - One ad-hoc single program syscall is removed - gssd_syscall. Note: > > rpctls syscall remains, but I have some ideas on how to improve that,= too. > > Not at this step though. > > - All sleeps of kernel RPC calls are now in single place, and they all = have > > timeouts. I believe NFS services are now much more resilient to hang= s. > > A deadlock when NFS kernel thread is blocked on unix socket buffer, a= nd > > the socket can't go away because its application is blocked in some o= ther > > syscall is no longer possible. > > > > The code is posted on phabricator, reviews D48547 through D48552. > > Reviewers are very welcome! > > > > I share my branch on Github. It is usually rebased on today's CURRENT: > > > > https://github.com/glebius/FreeBSD/commits/gss-netlink/ > > > > Early testers are very welcome! > Ok, I can now do minimal testing and crashed it... > > I did a mount with option "tls" and then partitioned it from the NFS serv= er > by doing "ifconfig bridge0 down". Waited until the TCP connection closed > and then did "ifconfig bridge0 up". > > The crash is a NULL pointer at rpctls_impl.c:255 (in rpctls_connect(), > called from nfscl_renewthread(). > The problem is that you made rpctls_connect_handle a vnet'd variable. > The client side (aka an NFS mount) does not happen inside a jail and > cannot use any vnet'd variables. > Why? Well, any number of threads enter the NFS client via VOP_xxx() > calls etc. Any one of them might end up doing a TCP reconnect when the > underlying TCP connection is broken and then heals. > > I don't know why you made rpctls_connect_handle a vnet'd variable, > but it cannot be that way. > (I once looked at making NFS mounts work inside a vnet prison and > gave up when I realized any old thread ends up in the code and it > would have taken many, many CURVNET_SET() calls to make it work.) > > In summary, no global variable on the client side can be vnet'd and no > global variable on the server side that is vnet'd can be shared with the > client side code. Ok,I now see you've fixed this crash. I'd still like to limit commits to main to the ones that are required to us= e netlink for the upcalls at this time. rick > > I realize you are enthusiastic about this, but I'd suggest you back off t= o > the minimal changes required to make this stuff work with netlink instead > of unix domain sockets and stick with that, at least for the initial > commit cycle. > > One thing to note is that few (if any) people who run main test this stuf= f. > It may be 1-2years before it sees third party testing and I can only do m= inimal > testing until at least April. > > Anyhow, thanks for all the good work you are doing with this, rick > > > > > -- > > Gleb Smirnoff > >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAM5tNy5EBUj6k0%2BXw0TwetVR0xx0pp5i2G3WC9L4wFyEnnmDWw>