Re: [RFC PATCH 1/1] mount.nfs: Fix mounting on tmpfs

[Petr Vorel <pvorel@suse.cz>]

Hi Bruce,

> On Fri, Apr 23, 2021 at 04:17:52AM +0200, Petr Vorel wrote:
> > Hi,

> > > On Thu, Apr 22, 2021 at 09:18:03PM +0200, Petr Vorel wrote:
> > > > LTP NFS tests (which use netns) fails on tmpfs since d4066486:

> > > > mount -t nfs -o proto=tcp,vers=4.2 10.0.0.2:/tmp/ltp.nfs01.nfs-4.2/LTP_nfs01.UF6gRZCy3O/4.2/tcp /tmp/ltp.nfs01.nfs-4.2/LTP_nfs01.UF6gRZCy3O/4.2/0
> > > > mount.nfs: mounting 10.0.0.2:/tmp/ltp.nfs01.nfs-4.2/LTP_nfs01.UF6gRZCy3O/4.2/tcp failed, reason given by server: No such file or directory

> > > We should figure out the reason for the failure.  A network trace might
> > > help.

> > Anything specific you're looking for?

> Actually I was thinking of capturing the network traffic, something
> like:
> 	tcpdump -s0 -wtmp.pcap -i<interface>

> then try the mount, then kill tcpdump and look at tmp.pcap.

I don't see anything suspicious, can you please have a look?
https://gitlab.com/pevik/tmp/-/raw/master/nfs.v3.pcap
https://gitlab.com/pevik/tmp/-/raw/master/nfs.v4.pcap
https://gitlab.com/pevik/tmp/-/raw/master/nfs.v4.1.pcap
https://gitlab.com/pevik/tmp/-/raw/master/nfs.v4.2.pcap

tcpdump -s0 -iany host 10.0.0.1 and 10.0.0.2

> First, though, what's the output of "exportfs -v" on the server?
* v3 (the only working)
mount -t nfs -o proto=tcp,vers=3 10.0.0.2:/tmp/LTP_nfs01.S5dolLhIlD/3/tcp /tmp/LTP_nfs01.S5dolLhIlD/3/0

exportfs -v
/tmp/LTP_nfs01.S5dolLhIlD/3/tcp
		<world>(sync,wdelay,hide,no_subtree_check,fsid=6436,sec=sys,rw,secure,no_root_squash,no_all_squash)

* v4
mount -t nfs -o proto=tcp,vers=4 10.0.0.2:/tmp/LTP_nfs01.5yzuZYRSRl/4/tcp /tmp/LTP_nfs01.5yzuZYRSRl/4/0
mount.nfs: mounting 10.0.0.2:/tmp/LTP_nfs01.5yzuZYRSRl/4/tcp failed, reason given by server: No such file or directory

exportfs -v
/tmp/LTP_nfs01.5yzuZYRSRl/4/tcp
		<world>(sync,wdelay,hide,no_subtree_check,fsid=6695,sec=sys,rw,secure,no_root_squash,no_all_squash)

* v4.1
mount -t nfs -o proto=tcp,vers=4.1 10.0.0.2:/tmp/LTP_nfs01.xSWfcygtYM/4.1/tcp /tmp/LTP_nfs01.xSWfcygtYM/4.1/0
mount.nfs: mounting 10.0.0.2:/tmp/LTP_nfs01.xSWfcygtYM/4.1/tcp failed, reason given by server: No such file or directory

exportfs -v
/tmp/LTP_nfs01.xSWfcygtYM/4.1/tcp
		<world>(sync,wdelay,hide,no_subtree_check,fsid=6965,sec=sys,rw,secure,no_root_squash,no_all_squash)

* v4.2
mount -t nfs -o proto=tcp,vers=4.2 10.0.0.2:/tmp/LTP_nfs01.xkKpqpRikV/4.2/tcp /tmp/LTP_nfs01.xkKpqpRikV/4.2/0
mount.nfs: mounting 10.0.0.2:/tmp/LTP_nfs01.xkKpqpRikV/4.2/tcp failed, reason given by server: No such file or directory

exportfs -v
/tmp/LTP_nfs01.xkKpqpRikV/4.2/tcp
		<world>(sync,wdelay,hide,no_subtree_check,fsid=7239,sec=sys,rw,secure,no_root_squash,no_all_squash)


> Note you need an "fsid=" option on tmpfs exports.
Yes, the test uses PID based fsid: fsid=$$

> --b.

Thanks a lot for your time!

Kind regards,
Petr