On Mon, 2023-06-05 at 10:23 -0400, Steve Dickson wrote:

On 6/1/23 3:46 PM, Scott Mayhew wrote:

quoted

Scott Mayhew (3):
   nfs(5): Document the softerr mount option.

My only thought about this one, is do we want document
an option we do people using since it will cause data
corruption?

Personally I would be for ripping out all of the soft doc
from the man page.

Softerr was explicitly designed for use when re-exporting NFS. If you
use a hard mount, you will find that if one of the NFS servers being
re-exported goes down, eventually all your knfsd threads lock up. By
timing out, and returning an error, 'softerr' prevents that scenario.

The difference between using 'soft' and 'softerr' here lies in the fact
that knfsd will convert the ETIMEOUT into NFS3ERR_JUKEBOX /
NFS4ERR_DELAY for the NFS clients, causing it to retry the operation.
OTOH, 'soft' returns EIO, which gets converted to NFS3ERR_IO /
NFS4ERR_IO, which does cause the client to error out and lose data.

IOW: this is an option that has a definite use case.

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com