Re: [PATCH/RFC nfs-utils] Fix NFSv4 export of tmpfs filesystems.

[Petr Vorel <pvorel@suse.cz>]

Hi Neil,

> [[This is a proposed fix.  It seems to work.  I'd like
>   some review comments before it is committed.
>   Petr: it would be great if you could test it to confirm
>   it actually works in your case.
> ]]
Thanks for a quick fix. It runs nicely in newer kernels (5.11.12-1-default
openSUSE and 5.10.0-6-amd64 Debian). But it somehow fails on older ones
(SLES 5.3.18-54-default heavily patched and 4.9.0-11-amd64).

I have some problem on Debian with 4.9.0-11-amd64 fails on both tmpfs and ext4,
others work fine (testing tmpfs, btrfs and ext4). But maybe I did something
wrong during testing. I did:
cp ./utils/mountd/mountd /usr/sbin/rpc.mountd
systemctl restart nfs-mountd.service

Failure is regardless I use new mount.nfs (master) or the original from
Debian (1.3.3).

strace looks nearly the same on tmpfs and ext4:
socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) = 5
fcntl(5, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(5, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
connect(5, {sa_family=AF_INET, sin_port=htons(111), sin_addr=inet_addr("10.0.0.2")}, 16) = -1 EINPROGRESS (Operation now in progress)
select(6, NULL, [5], NULL, {tv_sec=10, tv_usec=0}) = 1 (out [5], left {tv_sec=9, tv_usec=999997})
getsockopt(5, SOL_SOCKET, SO_ERROR, [0], [4]) = 0
fcntl(5, F_SETFL, O_RDWR)               = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
getpeername(5, {sa_family=AF_INET, sin_port=htons(111), sin_addr=inet_addr("10.0.0.2")}, [128->16]) = 0
getsockname(5, {sa_family=AF_INET, sin_port=htons(54140), sin_addr=inet_addr("10.0.0.1")}, [128->16]) = 0
getsockopt(5, SOL_SOCKET, SO_TYPE, [1], [4]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
getpid()                                = 920
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
write(5, "\200\0\0008bZ\360\303\0\0\0\0\0\0\0\2\0\1\206\240\0\0\0\2\0\0\0\3\0\0\0\0"..., 60) = 60
poll([{fd=5, events=POLLIN}], 1, 9999)  = 1 ([{fd=5, revents=POLLIN}])
read(5, "\200\0\0\34bZ\360\303\0\0\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\10\1", 65536) = 32
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
close(5)                                = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) = 5
fcntl(5, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(5, F_SETFL, O_RDWR|O_NONBLOCK)    = 0

Kind regards,
Petr