Merge branch 'akpm' (updates from Andrew Morton)

Merge first patch-bomb from Andrew Morton:
 - various misc bits
 - I'm been patchmonkeying ocfs2 for a while, as Joel and Mark have been
   distracted.  There has been quite a bit of activity.
 - About half the MM queue
 - Some backlight bits
 - Various lib/ updates
 - checkpatch updates
 - zillions more little rtc patches
 - ptrace
 - signals
 - exec
 - procfs
 - rapidio
 - nbd
 - aoe
 - pps
 - memstick
 - tools/testing/selftests updates

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (445 commits)
  tools/testing/selftests: don't assume the x bit is set on scripts
  selftests: add .gitignore for kcmp
  selftests: fix clean target in kcmp Makefile
  selftests: add .gitignore for vm
  selftests: add hugetlbfstest
  self-test: fix make clean
  selftests: exit 1 on failure
  kernel/resource.c: remove the unneeded assignment in function __find_resource
  aio: fix wrong comment in aio_complete()
  drivers/w1/slaves/w1_ds2408.c: add magic sequence to disable P0 test mode
  drivers/memstick/host/r592.c: convert to module_pci_driver
  drivers/memstick/host/jmb38x_ms: convert to module_pci_driver
  pps-gpio: add device-tree binding and support
  drivers/pps/clients/pps-gpio.c: convert to module_platform_driver
  drivers/pps/clients/pps-gpio.c: convert to devm_* helpers
  drivers/parport/share.c: use kzalloc
  Documentation/accounting/getdelays.c: avoid strncpy in accounting tool
  aoe: update internal version number to v83
  aoe: update copyright date
  aoe: perform I/O completions in parallel
  ...

1 files changed, 50 insertions, 5 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 746af55b8455..36af6eeaa67e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -212,7 +212,7 @@ static unsigned long scan_swap_map(struct swap_info_struct *si,
 			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 @@ checks:
 
 	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 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
 	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 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 			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 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	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);