diff --git a/include/linux/swap.h b/include/linux/swap.h
index 85d7437..d95cde5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -20,10 +20,13 @@
 #define SWAP_FLAG_PREFER	0x8000	/* set if swap priority specified */
 #define SWAP_FLAG_PRIO_MASK	0x7fff
 #define SWAP_FLAG_PRIO_SHIFT	0
-#define SWAP_FLAG_DISCARD	0x10000 /* discard swap cluster after use */
+#define SWAP_FLAG_DISCARD	0x10000 /* enable discard for swap */
+#define SWAP_FLAG_DISCARD_ONCE	0x20000 /* discard swap area at swapon-time */
+#define SWAP_FLAG_DISCARD_PAGES 0x40000 /* discard page-clusters after use */
 
 #define SWAP_FLAGS_VALID	(SWAP_FLAG_PRIO_MASK | SWAP_FLAG_PREFER | \
-				 SWAP_FLAG_DISCARD)
+				 SWAP_FLAG_DISCARD | SWAP_FLAG_DISCARD_ONCE | \
+				 SWAP_FLAG_DISCARD_PAGES)
 
 static inline int current_is_kswapd(void)
 {
@@ -147,14 +150,16 @@
 enum {
 	SWP_USED	= (1 << 0),	/* is slot in swap_info[] used? */
 	SWP_WRITEOK	= (1 << 1),	/* ok to write to this swap?	*/
-	SWP_DISCARDABLE = (1 << 2),	/* swapon+blkdev support discard */
+	SWP_DISCARDABLE = (1 << 2),	/* blkdev support discard */
 	SWP_DISCARDING	= (1 << 3),	/* now discarding a free cluster */
 	SWP_SOLIDSTATE	= (1 << 4),	/* blkdev seeks are cheap */
 	SWP_CONTINUED	= (1 << 5),	/* swap_map has count continuation */
 	SWP_BLKDEV	= (1 << 6),	/* its a block device */
 	SWP_FILE	= (1 << 7),	/* set after swap_activate success */
+	SWP_AREA_DISCARD = (1 << 8),	/* single-time swap area discards */
+	SWP_PAGE_DISCARD = (1 << 9),	/* freed swap page-cluster discards */
 					/* add others here before... */
-	SWP_SCANNING	= (1 << 8),	/* refcount in scan_swap_map */
+	SWP_SCANNING	= (1 << 10),	/* refcount in scan_swap_map */
 };
 
 #define SWAP_CLUSTER_MAX 32UL
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 746af55b..36af6ee 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -212,7 +212,7 @@
 			si->cluster_nr = SWAPFILE_CLUSTER - 1;
 			goto checks;
 		}
-		if (si->flags & SWP_DISCARDABLE) {
+		if (si->flags & SWP_PAGE_DISCARD) {
 			/*
 			 * Start range check on racing allocations, in case
 			 * they overlap the cluster we eventually decide on
@@ -322,7 +322,7 @@
 
 	if (si->lowest_alloc) {
 		/*
-		 * Only set when SWP_DISCARDABLE, and there's a scan
+		 * Only set when SWP_PAGE_DISCARD, and there's a scan
 		 * for a free cluster in progress or just completed.
 		 */
 		if (found_free_cluster) {
@@ -2016,6 +2016,20 @@
 	return nr_extents;
 }
 
+/*
+ * Helper to sys_swapon determining if a given swap
+ * backing device queue supports DISCARD operations.
+ */
+static bool swap_discardable(struct swap_info_struct *si)
+{
+	struct request_queue *q = bdev_get_queue(si->bdev);
+
+	if (!q || !blk_queue_discard(q))
+		return false;
+
+	return true;
+}
+
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 {
 	struct swap_info_struct *p;
@@ -2123,8 +2137,37 @@
 			p->flags |= SWP_SOLIDSTATE;
 			p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
 		}
-		if ((swap_flags & SWAP_FLAG_DISCARD) && discard_swap(p) == 0)
-			p->flags |= SWP_DISCARDABLE;
+
+		if ((swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
+			/*
+			 * When discard is enabled for swap with no particular
+			 * policy flagged, we set all swap discard flags here in
+			 * order to sustain backward compatibility with older
+			 * swapon(8) releases.
+			 */
+			p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
+				     SWP_PAGE_DISCARD);
+
+			/*
+			 * By flagging sys_swapon, a sysadmin can tell us to
+			 * either do single-time area discards only, or to just
+			 * perform discards for released swap page-clusters.
+			 * Now it's time to adjust the p->flags accordingly.
+			 */
+			if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
+				p->flags &= ~SWP_PAGE_DISCARD;
+			else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
+				p->flags &= ~SWP_AREA_DISCARD;
+
+			/* issue a swapon-time discard if it's still required */
+			if (p->flags & SWP_AREA_DISCARD) {
+				int err = discard_swap(p);
+				if (unlikely(err))
+					printk(KERN_ERR
+					       "swapon: discard_swap(%p): %d\n",
+						p, err);
+			}
+		}
 	}
 
 	mutex_lock(&swapon_mutex);
@@ -2135,11 +2178,13 @@
 	enable_swap_info(p, prio, swap_map, frontswap_map);
 
 	printk(KERN_INFO "Adding %uk swap on %s.  "
-			"Priority:%d extents:%d across:%lluk %s%s%s\n",
+			"Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
 		p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
 		nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
 		(p->flags & SWP_SOLIDSTATE) ? "SS" : "",
 		(p->flags & SWP_DISCARDABLE) ? "D" : "",
+		(p->flags & SWP_AREA_DISCARD) ? "s" : "",
+		(p->flags & SWP_PAGE_DISCARD) ? "c" : "",
 		(frontswap_map) ? "FS" : "");
 
 	mutex_unlock(&swapon_mutex);