On Fri, 2009-05-01 at 02:25 +0300, Benny Halevy wrote:
> From: Ricardo Labiaga <Ricardo.Labiaga@xxxxxxxxxx>
>
> Validates the callback's sessionID, the slot number, and the sequence ID.
> Increments the slot's sequence.
>
> Detects replays, but simply prints a debug message (if debugging is enabled
> since we don't yet implement a duplicate request cache for the backchannel.
> This should not present a problem, since only idempotent callbacks are
> currently implemented.
>
> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@xxxxxxxxxx>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> ---
> fs/nfs/callback_proc.c | 75 ++++++++++++++++++++++++++++++++++++++++++++----
> 1 files changed, 69 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
> index 6b342e8..c85d66f 100644
> --- a/fs/nfs/callback_proc.c
> +++ b/fs/nfs/callback_proc.c
> @@ -105,6 +105,57 @@ out:
> #if defined(CONFIG_NFS_V4_1)
>
> /*
> + * Validate the sequenceID sent by the server.
> + * Return success if the sequenceID is one more than what we last saw on
> + * this slot, accounting for wraparound. Increments the slot's sequence.
> + *
> + * We don't yet implement a duplicate request cache, so at this time
> + * we will log replays, and process them as if we had not seen them before,
> + * but we don't bump the sequence in the slot. Not too worried about it,
> + * since we only currently implement idempotent callbacks anyway.
> + *
> + * We have a single slot backchannel at this time, so we don't bother
> + * checking the used_slots bit array on the table. The lower layer guarantees
> + * a single outstanding callback request at a time.
> + */
> +static int
> +validate_seqid(struct nfs4_slot_table *tbl, u32 slotid, u32 seqid)
> +{
> + struct nfs4_slot *slot;
> +
> + dprintk("%s enter. slotid %d seqid %d\n",
> + __func__, slotid, seqid);
> +
> + if (slotid > NFS41_BC_MAX_CALLBACKS)
> + return NFS4ERR_BADSLOT;
I thought we agreed to always return error values as _negative_? Why the
change here?
> +
> + slot = tbl->slots + slotid;
> + dprintk("%s slot table seqid: %d\n", __func__, slot->seq_nr);
> +
> + /* Normal */
> + if (likely(seqid == slot->seq_nr + 1)) {
> + slot->seq_nr++;
> + return NFS4_OK;
> + }
> +
> + /* Replay */
> + if (seqid == slot->seq_nr) {
> + dprintk("%s seqid %d is a replay - no DRC available\n",
> + __func__, seqid);
> + return NFS4_OK;
> + }
> +
> + /* Wraparound */
> + if (seqid == 1 && (slot->seq_nr + 1) == 0) {
> + slot->seq_nr = 1;
> + return NFS4_OK;
> + }
> +
> + /* Misordered request */
> + return NFS4ERR_SEQ_MISORDERED;
> +}
> +
> +/*
> * Returns a pointer to a held 'struct nfs_client' that matches the server's
> * address, major version number, and session ID. It is the caller's
> * responsibility to release the returned reference.
> @@ -140,18 +191,27 @@ out:
> return NULL;
> }
>
> -/* FIXME: validate args->cbs_{sequence,slot}id */
> /* FIXME: referring calls should be processed */
> unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
> struct cb_sequenceres *res)
> {
> - int i;
> - unsigned status = 0;
> + struct nfs_client *clp;
> + int i, status;
>
> for (i = 0; i < args->csa_nrclists; i++)
> kfree(args->csa_rclists[i].rcl_refcalls);
> kfree(args->csa_rclists);
>
> + status = NFS4ERR_BADSESSION;
> + clp = find_client_with_session(args->csa_addr, 4, &args->csa_sessionid);
> + if (clp == NULL)
> + goto out;
> +
> + status = validate_seqid(&clp->cl_session->bc_slot_table,
> + args->csa_slotid, args->csa_sequenceid);
> + if (status)
> + goto out_putclient;
> +
> memcpy(&res->csr_sessionid, &args->csa_sessionid,
> sizeof(res->csr_sessionid));
> res->csr_sequenceid = args->csa_sequenceid;
> @@ -159,9 +219,12 @@ unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
> res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
> res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
>
> - dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
> - res->csr_status = status;
> - return status;
> +out_putclient:
> + nfs_put_client(clp);
> +out:
> + dprintk("%s: exit with status = %d\n", __func__, status);
> + res->csr_status = htonl(status);
> + return res->csr_status;
> }
>
> #endif /* CONFIG_NFS_V4_1 */
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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