mount.nfs: improve version negotiation when vers=4 is specified.

If NFSv4, in general, is requested (possibly by -t nfs4 or -o v4 or -o
vers=4 etc) then we need to negotiate the best minor version, but must
not fallback to v3 or v2.  Internally, this state is reflected in v_mode
== V_GENERAL.  This means that a major version was given, but the minor
version still needs to be negotiated.

This is handled by nfs_autonegotiate(). It currently does the right
thing for EPROTONOSUPPORT and EINVAL, but not for other errors.
In particular, ENOENT can cause problems as  NFSv4 might export
a different namespace than NFSv3 (e.g. by using fsid=0 in the Linux
NFS server).  Currently a mount request for NFSv4 and a particular path
can result if an NFSv3 mount if the path is available with v3 but
not v4.

So move the special handling of V_GENERAL into the common fall_back:
code, and add extra checking in the ENCONNREFUSED case, which does
not use fall_back:.

Tested-by: Steve Dickson <steved@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

0 files changed, 0 insertions, 0 deletions