Date: Thu, 24 Aug 2023 18:52:12 -0700 From: Rick Macklem <rick.macklem@gmail.com> To: J David <j.david.lists@gmail.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: NFS client hang on 13.2-RELEASE-p2 on file locking / wrong interface selected Message-ID: <CAM5tNy6ZLgyBwvjWGRGByTMLkso4jQ-VXVLyJ1sri15FmXC%2BcQ@mail.gmail.com> In-Reply-To: <CABXB=RRgyDzZDKPgxL6fwJCbrnyK-JR%2B1nAS3nYpW95_RN6g=A@mail.gmail.com> References: <CABXB=RTGZ-4MDB7MBoDMzGU6K3xnVU8e7gxkzpGkA2sQ-Sw0Xw@mail.gmail.com> <CAM5tNy5o44W7qc=DuX75y9C7SME8nfmWJ1DxThHmLTV-FENP4Q@mail.gmail.com> <CABXB=RRgyDzZDKPgxL6fwJCbrnyK-JR%2B1nAS3nYpW95_RN6g=A@mail.gmail.com>
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On Thu, Aug 24, 2023 at 10:25=E2=80=AFAM J David <j.david.lists@gmail.com> =
wrote:
>
> On Thu, Aug 24, 2023 at 10:02=E2=80=AFAM Rick Macklem <rick.macklem@gmail=
.com> wrote:
> > Otherwise consider switching the mounts to NFSv4.1/4.2.
>
> Unfortunately, NFSv4 is worse.
>
> Under NFSv4.2, attempts to lock files that previously did not exist on
> NFS servers work, but any attempt to lock an existing file, regardless
> of permissions, inexplicably fails with "Permission denied."
>
> E.g.:
>
> $ lockf -k x sleep 3 && echo OK
> OK
> $ lockf -k x sleep 3 && echo OK
> lockf: cannot open x: Permission denied
Here's a snippet from "man lockf"
-w Causes lockd to open file for writing rather than
reading. This is necessary on filesystems (including
NFSv4) where a file which has been opened read-only
cannot be exclusively locked.
I am pretty sure this is in 13.2, although I do not remember when it
was added to "lockf".
rick
> $ rm x
> $ lockf -k x sleep 3 && echo OK
> OK
> $ ktrace lockf -k x sleep 3 && echo OK
> lockf: cannot open x: Permission denied
> $ echo "what" >x
> $ cat x
> what
>
> From ktrace:
>
> 98614 lockf CALL
> openat(AT_FDCWD,0x295c0979e8f1,0x224<O_RDONLY|O_NONBLOCK|O_EXLOCK|O_CREAT=
>,0666<S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH>)
> 98614 lockf NAMI "x"
> 98614 lockf RET openat -1 errno 13 Permission denied
>
> Thanks!
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