afs: Return ENOENT if no cell DNS record can be found

Make AFS return error ENOENT if no cell SRV or AFSDB DNS record (or
cellservdb config file record) can be found rather than returning
EDESTADDRREQ.

Also add cell name lookup info to the cursor dump.

Fixes: d5c32c8 ("afs: Fix cell DNS lookup")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216637
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

Author: dhowells

fs/afs/vl_rotate.c

@@ -58,6 +58,12 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
 		}
 
 		/* Status load is ordered after lookup counter load */
+		if (cell->dns_status == DNS_LOOKUP_GOT_NOT_FOUND) {
+			pr_warn("No record of cell %s\n", cell->name);
+			vc->error = -ENOENT;
+			return false;
+		}
+
 		if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
 			vc->error = -EDESTADDRREQ;
 			return false;
@@ -285,6 +291,7 @@ bool afs_select_vlserver(struct afs_vl_cursor *vc)
  */
 static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 {
+	struct afs_cell *cell = vc->cell;
 	static int count;
 	int i;
 
@@ -294,6 +301,9 @@ static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 
 	rcu_read_lock();
 	pr_notice("EDESTADDR occurred\n");
+	pr_notice("CELL: %s err=%d\n", cell->name, cell->error);
+	pr_notice("DNS: src=%u st=%u lc=%x\n",
+		  cell->dns_source, cell->dns_status, cell->dns_lookup_count);
 	pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
 		  vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);