Merge branch 'akpm-current/current'

1 files changed, 32 insertions, 13 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 178130880b90..fba7960bb026 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -37,6 +37,7 @@
 #include <linux/swapfile.h>
 #include <linux/export.h>
 #include <linux/swap_slots.h>
+#include <linux/sort.h>
 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
@@ -335,7 +336,7 @@ static void cluster_list_add_tail(struct swap_cluster_list *list,
 		ci_tail = ci + tail;
 		spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING);
 		cluster_set_next(ci_tail, idx);
-		unlock_cluster(ci_tail);
+		spin_unlock(&ci_tail->lock);
 		cluster_set_next_flag(&list->tail, idx, 0);
 	}
 }
@@ -672,6 +673,9 @@ checks:
 		else
 			goto done;
 	}
+	si->swap_map[offset] = usage;
+	inc_cluster_info_page(si, si->cluster_info, offset);
+	unlock_cluster(ci);
 
 	if (offset == si->lowest_bit)
 		si->lowest_bit++;
@@ -685,9 +689,6 @@ checks:
 		plist_del(&si->avail_list, &swap_avail_head);
 		spin_unlock(&swap_avail_lock);
 	}
-	si->swap_map[offset] = usage;
-	inc_cluster_info_page(si, si->cluster_info, offset);
-	unlock_cluster(ci);
 	si->cluster_next = offset + 1;
 	slots[n_ret++] = swp_entry(si->type, offset);
 
@@ -1065,6 +1066,13 @@ void swapcache_free(swp_entry_t entry)
 	}
 }
 
+static int swp_entry_cmp(const void *ent1, const void *ent2)
+{
+	const swp_entry_t *e1 = ent1, *e2 = ent2;
+
+	return (long)(swp_type(*e1) - swp_type(*e2));
+}
+
 void swapcache_free_entries(swp_entry_t *entries, int n)
 {
 	struct swap_info_struct *p, *prev;
@@ -1075,6 +1083,10 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
 
 	prev = NULL;
 	p = NULL;
+
+	/* Sort swap entries by swap device, so each lock is only taken once. */
+	if (nr_swapfiles > 1)
+		sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL);
 	for (i = 0; i < n; ++i) {
 		p = swap_info_get_cont(entries[i], prev);
 		if (p)
@@ -1111,6 +1123,18 @@ int page_swapcount(struct page *page)
 	return count;
 }
 
+static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
+{
+	int count = 0;
+	pgoff_t offset = swp_offset(entry);
+	struct swap_cluster_info *ci;
+
+	ci = lock_cluster_or_swap_info(si, offset);
+	count = swap_count(si->swap_map[offset]);
+	unlock_cluster_or_swap_info(si, ci);
+	return count;
+}
+
 /*
  * How many references to @entry are currently swapped out?
  * This does not give an exact answer when swap count is continued,
@@ -1119,17 +1143,11 @@ int page_swapcount(struct page *page)
 int __swp_swapcount(swp_entry_t entry)
 {
 	int count = 0;
-	pgoff_t offset;
 	struct swap_info_struct *si;
-	struct swap_cluster_info *ci;
 
 	si = __swap_info_get(entry);
-	if (si) {
-		offset = swp_offset(entry);
-		ci = lock_cluster_or_swap_info(si, offset);
-		count = swap_count(si->swap_map[offset]);
-		unlock_cluster_or_swap_info(si, ci);
-	}
+	if (si)
+		count = swap_swapcount(si, entry);
 	return count;
 }
 
@@ -1291,7 +1309,8 @@ int free_swap_and_cache(swp_entry_t entry)
 		 * Also recheck PageSwapCache now page is locked (above).
 		 */
 		if (PageSwapCache(page) && !PageWriteback(page) &&
-		    (!page_mapped(page) || mem_cgroup_swap_full(page))) {
+		    (!page_mapped(page) || mem_cgroup_swap_full(page)) &&
+		    !swap_swapcount(p, entry)) {
 			delete_from_swap_cache(page);
 			SetPageDirty(page);
 		}