Kernel 5.1.x breaks NFS ?

Message

Myu · Post by **Myu** » Sat May 18, 2019 2:20 pm

Hello fine folks,

So I updated my kernel from 5.0.16 to 5.1.3, putting all new config at "not set" and booting the 5.1.3 kernel, I can still mount my NFS drive but if I try to read it with ls(1), I have an Input/Output error.

Strangely, I can cd(1) to subfolders but ls(1) still behaves the same.

My NFS fileserver is running NFSv3 on DragonFlyBSD 5.4.2, it still works fine with 5.0.16.

Anyone with the same issue or any pointers to debug this behavior ?

Cheers,

-- Myu

Jaglover · Post by **Jaglover** » Sat May 18, 2019 6:16 pm

One of my NFS servers runs FreeBSD-12 with NFSv3, just upgraded to 5.1.3 and there is no problem.

szatox · Post by **szatox** » Sat May 18, 2019 7:17 pm

Permissions issue?
Like in: are you allowed to read this directory? it can produce bizzare results...
Perhaps your user mapping has changed, so you no longer connect as the user you think you connect.. NFS uses numeric uids on both ends, and there was some translation daemon added... Accidentally flipping the switch on or off could be confusing.

Myu · Post by **Myu** » Mon May 20, 2019 8:29 am

Thanks for the reply guys !

Permissions issue?
Like in: are you allowed to read this directory? it can produce bizzare results...

I am able to read the directory on 5.0.x and I didn't change my permissions.

Perhaps your user mapping has changed, so you no longer connect as the user you think you connect..

I doubt it, if I go back to 5.0.x, I can use it just fine

NFS uses numeric uids on both ends, and there was some translation daemon added...

A translation deamon has been added in 5.1.x ? I would be interested to know more about it if you have any pointers

Accidentally flipping the switch on or off could be confusing.

Which switch in this case ?

Cheers,

-- Myu

szatox · Post by **szatox** » Mon May 20, 2019 6:33 pm

Q: How do you know you've had enough for tonight?
A: Your fork only has a single tooth, but it came with 4 handles!

I'm really impressed with your interpretation. My point was supposed to be _handled_ the other way around

I am able to read the directory on 5.0.x

You said you can't ls that directory over NFS. Reading directories is pretty much the only thing ls does. Cd does not read directories. It simply enters them. The former needs r permission, the latter needs x. In case of directories, both bits are independent of each other.

Deamon translating UIDs on the client to UIDs on the server was added much earlier. I think it was around the same time NFS4 came out, though those 2 things were mostly unrelated. The intended purpose was to replace matching users on numeric IDs with matching users on names. If you have any differences in /etc/passwd between systems, you can run into some weird problems when enabling or disabling this feature.

Anyway... NFS doesn't log much by default. Try enabling debug log and then messing around with your client. Maybe it would simply tell you what's the problem?