On 05/31/2017 08:22 PM, NeilBrown wrote:
>
> 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@xxxxxxxxxx>
> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Committed... with the addition change to nfs_set_version()
which stops -t nfs4 from rolling back to v3.
Thanks!
steved.
> ---
> utils/mount/stropts.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
> index 0fbb37569ef9..b20ad1c8bf55 100644
> --- a/utils/mount/stropts.c
> +++ b/utils/mount/stropts.c
> @@ -838,9 +838,6 @@ check_result:
> case EINVAL:
> /* A less clear indication that our client
> * does not support NFSv4 minor version. */
> - if (mi->version.v_mode == V_GENERAL &&
> - mi->version.minor == 0)
> - return result;
> if (mi->version.v_mode != V_SPECIFIC) {
> if (mi->version.minor > 0) {
> mi->version.minor--;
> @@ -862,6 +859,9 @@ check_result:
> /* UDP-Only servers won't support v4, but maybe it
> * just isn't ready yet. So try v3, but double-check
> * with rpcbind for v4. */
> + if (mi->version.v_mode == V_GENERAL)
> + /* Mustn't try v2,v3 */
> + return result;
> result = nfs_try_mount_v3v2(mi, TRUE);
> if (result == 0 && errno == EAGAIN) {
> /* v4 server seems to be registered now. */
> @@ -878,6 +878,9 @@ check_result:
> }
>
> fall_back:
> + if (mi->version.v_mode == V_GENERAL)
> + /* v2,3 fallback not allowed */
> + return result;
> return nfs_try_mount_v3v2(mi, FALSE);
> }
>
>
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