On Fri, 04 Oct 2024, NeilBrown wrote:
> If a timeout is specified in the mount options, it currently applies to
> both the NFS protocol and (with v3) the MOUNT protocol. This is
> sensible when they both use the same underlying protocol, or those
> protocols are compatible w.r.t timeouts as RDMA and TCP are.
>
> However if, for example, NFS is using TCP and MOUNT is using UDP then
> using the same timeout doesn't make much sense.
>
> If you
> mount -o vers=3,proto=tcp,mountproto=udp,timeo=600,retrans=5 \
> server:/path /mountpoint
>
> then the timeo=600 which was intended for the NFS/TCP request will
> apply to the MOUNT/UDP requests with the result that there will only be
> one request sent (because UDP has a maximum timeout of 60 seconds).
> This is not what a reasonable person might expect.
>
> This patch disables the sharing of timeout information in cases where
> the underlying protocols are not compatible.
>
> Fixes: c9301cb35b59 ("nfs: hornor timeo and retrans option when mounting NFSv3")
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> fs/nfs/super.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 9723b6c53397..ae5c5e39afa0 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -885,7 +885,15 @@ static int nfs_request_mount(struct fs_context *fc,
> * Now ask the mount server to map our export path
> * to a file handle.
> */
> - status = nfs_mount(&request, ctx->timeo, ctx->retrans);
> + if ((request.protocol == XPRT_TRANSPORT_UDP) ==
> + !(ctx->flags & NFS_MOUNT_TCP))
> + /*
> + * NFS protocol and mount protocol are both UDP or neither UDP
> + * so timeouts are compatible. Use NFS timeouts for MOUNT
> + */
> + status = nfs_mount(&request, ctx->timeo, ctx->retrans);
> + else
> + status = nfs_mount(&request, NFS_UNSPEC_TIMEO, NFS_UNSPEC_RETRANS);
> if (status != 0) {
> dfprintk(MOUNT, "NFS: unable to mount server %s, error %d\n",
> request.hostname, status);
> --
> 2.46.0
>
>
>
Anna, Trond: have you had a chance to look at this yet?
Thanks,
NeilBrown
