2 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index bf4eb62506db..7cdd63366f88 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -19,6 +19,7 @@ struct bio;
 #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 */
 
 static inline int current_is_kswapd(void)
 {
@@ -142,7 +143,7 @@ struct swap_extent {
 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),     /* blkdev supports discard */
+        SWP_DISCARDABLE = (1 << 2),     /* swapon+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 */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1894dead0b58..7c703ff2f36f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2047,7 +2047,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                         p->flags |= SWP_SOLIDSTATE;
                         p->cluster_next = 1 + (random32() % p->highest_bit);
                 }
-                if (discard_swap(p) == 0)
+                if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD))
                         p->flags |= SWP_DISCARDABLE;
         }