On Dec 8, 2021, at 10:54 AM, Dai Ngo [off-list ref] wrote:

On 12/6/21 11:55 AM, Chuck Lever III wrote:

quoted

quoted

+
+/*
+ * Function to check if the nfserr_share_denied error for 'fp' resulted
+ * from conflict with courtesy clients then release their state to resolve
+ * the conflict.
+ *
+ * Function returns:
+ *	 0 -  no conflict with courtesy clients
+ *	>0 -  conflict with courtesy clients resolved, try access/deny check again
+ *	-1 -  conflict with courtesy clients being resolved in background
+ *            return nfserr_jukebox to NFS client
+ */
+static int
+nfs4_destroy_clnts_with_sresv_conflict(struct svc_rqst *rqstp,
+			struct nfs4_file *fp, struct nfs4_ol_stateid *stp,
+			u32 access, bool share_access)
+{
+	int cnt = 0;
+	int async_cnt = 0;
+	bool no_retry = false;
+	struct nfs4_client *cl;
+	struct list_head *pos, *next, reaplist;
+	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+
+	INIT_LIST_HEAD(&reaplist);
+	spin_lock(&nn->client_lock);
+	list_for_each_safe(pos, next, &nn->client_lru) {
+		cl = list_entry(pos, struct nfs4_client, cl_lru);
+		/*
+		 * check all nfs4_ol_stateid of this client
+		 * for conflicts with 'access'mode.
+		 */
+		if (nfs4_check_deny_bmap(cl, fp, stp, access, share_access)) {
+			if (!test_bit(NFSD4_COURTESY_CLIENT, &cl->cl_flags)) {
+				/* conflict with non-courtesy client */
+				no_retry = true;
+				cnt = 0;
+				goto out;
+			}
+			/*
+			 * if too many to resolve synchronously
+			 * then do the rest in background
+			 */
+			if (cnt > 100) {
+				set_bit(NFSD4_DESTROY_COURTESY_CLIENT, &cl->cl_flags);
+				async_cnt++;
+				continue;
+			}
+			if (mark_client_expired_locked(cl))
+				continue;
+			cnt++;
+			list_add(&cl->cl_lru, &reaplist);
+		}
+	}

Bruce suggested simply returning NFS4ERR_DELAY for all cases.
That would simplify this quite a bit for what is a rare edge
case.

If we always do this asynchronously by returning NFS4ERR_DELAY
for all cases then the following pynfs tests need to be modified
to handle the error:

RENEW3   st_renew.testExpired                                     : FAILURE
LKU10    st_locku.testTimedoutUnlock                              : FAILURE
CLOSE9   st_close.testTimedoutClose2                              : FAILURE

and any new tests that opens file have to be prepared to handle
NFS4ERR_DELAY due to the lack of destroy_clientid in 4.0.

Do we still want to take this approach?

I'm still interested, but Bruce should chime in.

Maybe Calum could have a look under the covers of pynfs and see how difficult the change might be.


--
Chuck Lever