nfsd: eliminate cl_ra_cblist and NFSD4_CLIENT_CB_RECALL_ANY

deleg_reaper() will walk the client_lru list and put any suitable
entries onto "cblist" using the cl_ra_cblist pointer. It then walks the
objects outside the spinlock and queues callbacks for them.

None of the operations that deleg_reaper() does outside the
nn->client_lock are blocking operations. Just queue their workqueue jobs
under the nn->client_lock instead.

Also, the NFSD4_CLIENT_CB_RECALL_ANY and NFSD4_CALLBACK_RUNNING flags
serve an identical purpose now. Drop the NFSD4_CLIENT_CB_RECALL_ANY flag
and just use the one in the callback.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: jtlayton

fs/nfsd/nfs4state.c

@@ -3175,7 +3175,6 @@ nfsd4_cb_recall_any_release(struct nfsd4_callback *cb)
 {
 	struct nfs4_client *clp = cb->cb_clp;
 
-	clear_bit(NFSD4_CLIENT_CB_RECALL_ANY, &clp->cl_flags);
 	drop_client(clp);
 }
 
@@ -6881,7 +6880,6 @@ deleg_reaper(struct nfsd_net *nn)
 {
 	struct list_head *pos, *next;
 	struct nfs4_client *clp;
-	LIST_HEAD(cblist);
 
 	spin_lock(&nn->client_lock);
 	list_for_each_safe(pos, next, &nn->client_lru) {
@@ -6893,31 +6891,23 @@ deleg_reaper(struct nfsd_net *nn)
 			continue;
 		if (atomic_read(&clp->cl_delegs_in_recall))
 			continue;
-		if (test_bit(NFSD4_CLIENT_CB_RECALL_ANY, &clp->cl_flags))
+		if (test_and_set_bit(NFSD4_CALLBACK_RUNNING, &clp->cl_ra->ra_cb.cb_flags))
 			continue;
 		if (ktime_get_boottime_seconds() - clp->cl_ra_time < 5)
 			continue;
 		if (clp->cl_cb_state != NFSD4_CB_UP)
 			continue;
-		list_add(&clp->cl_ra_cblist, &cblist);
 
 		/* release in nfsd4_cb_recall_any_release */
 		kref_get(&clp->cl_nfsdfs.cl_ref);
-		set_bit(NFSD4_CLIENT_CB_RECALL_ANY, &clp->cl_flags);
 		clp->cl_ra_time = ktime_get_boottime_seconds();
-	}
-	spin_unlock(&nn->client_lock);
-
-	while (!list_empty(&cblist)) {
-		clp = list_first_entry(&cblist, struct nfs4_client,
-					cl_ra_cblist);
-		list_del_init(&clp->cl_ra_cblist);
 		clp->cl_ra->ra_keep = 0;
 		clp->cl_ra->ra_bmval[0] = BIT(RCA4_TYPE_MASK_RDATA_DLG) |
 						BIT(RCA4_TYPE_MASK_WDATA_DLG);
 		trace_nfsd_cb_recall_any(clp->cl_ra);
-		nfsd4_try_run_cb(&clp->cl_ra->ra_cb);
+		nfsd4_run_cb(&clp->cl_ra->ra_cb);
 	}
+	spin_unlock(&nn->client_lock);
 }
 
 static void

fs/nfsd/state.h

@@ -454,7 +454,6 @@ struct nfs4_client {
 #define NFSD4_CLIENT_UPCALL_LOCK	(5)	/* upcall serialization */
 #define NFSD4_CLIENT_CB_FLAG_MASK	(1 << NFSD4_CLIENT_CB_UPDATE | \
 					 1 << NFSD4_CLIENT_CB_KILL)
-#define NFSD4_CLIENT_CB_RECALL_ANY	(6)
 	unsigned long		cl_flags;
 
 	struct workqueue_struct *cl_callback_wq;
@@ -500,7 +499,6 @@ struct nfs4_client {
 
 	struct nfsd4_cb_recall_any	*cl_ra;
 	time64_t		cl_ra_time;
-	struct list_head	cl_ra_cblist;
 };
 
 /* struct nfs4_client_reset