Date: Fri, 1 Jan 2021 01:09:18 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: Chris Johns <chrisj@rtems.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: sys/fs/nfsclient on RTEMS gets a bad seqid error with open Message-ID: <YQXPR0101MB096874499E40F220D359B919DDD50@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM>
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>On 31/12/20 10:04 am, Rick Macklem wrote: >> Chris Johns wrote: >>> Hello, >>> >>> I am porting the kernel's nfsclient file system to the RTEMS port of FreeBSD. I >>> have ported across the FreeBSD file descriptors, VFS and NFS code. I have a >>> custom pseudofs file system as my root file system and I can mount an NFSv4 >>> mount exported from a FreeBSD 12 box. >>> >>> When I open a file there are a some getattr RPC calls that are successful >>> however the open call (PUTFH, OPEN, GETATTR) results in the server returning the >>> bas seqid (10026) error code for the OPEN and I am not sure why this is >>> happening. I suspect I am missing a step in the nfsclient set up. >> Well, for NFSv4.0 Opens, there is a field in the open_owner called a "seqid', >> which is used to serialize Open calls. If that "seqid" gets screwed up, you >> get a "bad seqid" (10026) from the server and your mount is broken. > >There is only one open call being made and the seq id in the packet is 0. The >server code seems to consider ownership when returning this error and this is an >area I am not sure about. RTEMS simulates a process and does not have a normal >user/group model. Did you do a Setclientid, Setclientidconfirm to set up the clientid? The first Open should be fine with seqid==0 and the reply will flag it as "needs Openconfirm". --> 10026 means the server thinks it has already seen the open_owner string for that client. I'd suggest to capture a packet trace of a mount from the FreeBSD client and then look at it in wireshark, to see what should be happening. >> A couple of possibilities: >> - The FreeBSD client code depends on an exclusive lock on the vnode >> to serialize the Opens. > >There is only one open call active. This is something I can control. If all your Opens are serialized, you can use a single open_owner for everything. The open_owner string should always be the same to do this. The FreeBSD client can do this for NFSv4.1 by specifying "oneopenown" as a mount option. >> --> If what you are doing doesn't serialize them, then that will be a >> problem. >> - If the VOP_OPEN() generates an unexpected error (I just ran into this >> on FreeBSD head), then the client might not get things correct. >> --> The seqid is incremented for some errors, but not others. > >I am currently basing this work on the FreeBSD 12 branch we have. A master port >is next. > > Btw, all this seqid stuff goes away when you use NFSv4.1 and there > are NFSv4.1 only clients out there. You might want to consider doing > this. If I was writing the code now, there would be no NFSv4.0. > >Ah OK. How do I make the FreeBSD nfsclient operate as NFSv4.1? I looked into >this but I could not figure out how. minorversion=1 mount option, which sets nm_minorvers to 1. rick > rick > ps: Getting this seqid stuff right was about the hardest part of > implementing NFSv4.0 and it could still be buggy. Hmm yes it seems a little tricky. Thanks Chris
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