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-rw-r--r--include/linux/swap.h3
-rw-r--r--mm/swapfile.c2
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;
}