nfsd4: make backchannel sequence number per-session

Currently we don't deal well with a client that has multiple sessions
associated with it (even simultaneously, or serially over the lifetime
of the client).

In particular, we don't attempt to keep the backchannel running after
the original session diseappears.

We will fix that soon.

Once we do that, we need the slot sequence number to be per-session;
otherwise, for example, we cannot correctly handle a case like this:

	- All session 1 connections are lost.
	- The client creates session 2.  We use it for the backchannel
	  (since it's the only working choice).
	- The client gives us a new connection to use with session 1.
	- The client destroys session 2.

At this point our only choice is to go back to using session 1.  When we
do so we must use the sequence number that is next for session 1.  We
therefore need to maintain multiple sequence number streams.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 78ac779c09ff..5df9dda47bf4 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -260,7 +260,7 @@ encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_callback *cb,
 
         WRITE32(OP_CB_SEQUENCE);
         WRITEMEM(ses->se_sessionid.data, NFS4_MAX_SESSIONID_LEN);
-        WRITE32(cb->cb_clp->cl_cb_seq_nr);
+        WRITE32(ses->se_cb_seq_nr);
         WRITE32(0);             /* slotid, always 0 */
         WRITE32(0);             /* highest slotid always 0 */
         WRITE32(0);             /* cachethis always 0 */
@@ -369,7 +369,7 @@ decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_callback *cb,
                 goto out;
         }
         READ32(dummy);
-        if (dummy != cb->cb_clp->cl_cb_seq_nr) {
+        if (dummy != ses->se_cb_seq_nr) {
                 dprintk("%s Invalid sequence number\n", __func__);
                 goto out;
         }
@@ -643,11 +643,11 @@ static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
 
         if (clp->cl_cb_conn.cb_minorversion) {
                 /* No need for lock, access serialized in nfsd4_cb_prepare */
-                ++clp->cl_cb_seq_nr;
+                ++clp->cl_cb_session->se_cb_seq_nr;
                 clear_bit(0, &clp->cl_cb_slot_busy);
                 rpc_wake_up_next(&clp->cl_cb_waitq);
                 dprintk("%s: freed slot, new seqid=%d\n", __func__,
-                        clp->cl_cb_seq_nr);
+                        clp->cl_cb_session->se_cb_seq_nr);
 
                 /* We're done looking into the sequence information */
                 task->tk_msg.rpc_resp = NULL;