1 files changed, 56 insertions, 19 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 58877312cf6b..9f7bd5e8e68a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -932,11 +932,25 @@ int reuse_swap_page(struct page *page)
 	count = page_mapcount(page);
 	if (count <= 1 && PageSwapCache(page)) {
 		count += page_swapcount(page);
-		if (count == 1 && !PageWriteback(page)) {
+		if (count != 1)
+			goto out;
+		if (!PageWriteback(page)) {
 			delete_from_swap_cache(page);
 			SetPageDirty(page);
+		} else {
+			swp_entry_t entry;
+			struct swap_info_struct *p;
+
+			entry.val = page_private(page);
+			p = swap_info_get(entry);
+			if (p->flags & SWP_STABLE_WRITES) {
+				spin_unlock(&p->lock);
+				return false;
+			}
+			spin_unlock(&p->lock);
 		}
 	}
+out:
 	return count <= 1;
 }
 
@@ -2206,6 +2220,35 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
 	return 0;
 }
 
+
+/*
+ * Find out how many pages are allowed for a single swap device. There
+ * are two limiting factors:
+ * 1) the number of bits for the swap offset in the swp_entry_t type, and
+ * 2) the number of bits in the swap pte, as defined by the different
+ * architectures.
+ *
+ * In order to find the largest possible bit mask, a swap entry with
+ * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
+ * decoded to a swp_entry_t again, and finally the swap offset is
+ * extracted.
+ *
+ * This will mask all the bits from the initial ~0UL mask that can't
+ * be encoded in either the swp_entry_t or the architecture definition
+ * of a swap pte.
+ */
+unsigned long generic_max_swapfile_size(void)
+{
+	return swp_offset(pte_to_swp_entry(
+			swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+}
+
+/* Can be overridden by an architecture for additional checks. */
+__weak unsigned long max_swapfile_size(void)
+{
+	return generic_max_swapfile_size();
+}
+
 static unsigned long read_swap_header(struct swap_info_struct *p,
 					union swap_header *swap_header,
 					struct inode *inode)
@@ -2225,6 +2268,8 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
 		swab32s(&swap_header->info.version);
 		swab32s(&swap_header->info.last_page);
 		swab32s(&swap_header->info.nr_badpages);
+		if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+			return 0;
 		for (i = 0; i < swap_header->info.nr_badpages; i++)
 			swab32s(&swap_header->info.badpages[i]);
 	}
@@ -2239,23 +2284,12 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
 	p->cluster_next = 1;
 	p->cluster_nr = 0;
 
-	/*
-	 * Find out how many pages are allowed for a single swap
-	 * device. There are two limiting factors: 1) the number
-	 * of bits for the swap offset in the swp_entry_t type, and
-	 * 2) the number of bits in the swap pte as defined by the
-	 * different architectures. In order to find the
-	 * largest possible bit mask, a swap entry with swap type 0
-	 * and swap offset ~0UL is created, encoded to a swap pte,
-	 * decoded to a swp_entry_t again, and finally the swap
-	 * offset is extracted. This will mask all the bits from
-	 * the initial ~0UL mask that can't be encoded in either
-	 * the swp_entry_t or the architecture definition of a
-	 * swap pte.
-	 */
-	maxpages = swp_offset(pte_to_swp_entry(
-			swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+	maxpages = max_swapfile_size();
 	last_page = swap_header->info.last_page;
+	if (!last_page) {
+		pr_warn("Empty swap-file\n");
+		return 0;
+	}
 	if (last_page > maxpages) {
 		pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
 			maxpages << (PAGE_SHIFT - 10),
@@ -2461,6 +2495,10 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		error = -ENOMEM;
 		goto bad_swap;
 	}
+
+	if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
+		p->flags |= SWP_STABLE_WRITES;
+
 	if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
 		int cpu;
 
@@ -2540,8 +2578,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		  (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
 	enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
 
-	pr_info("Adding %uk swap on %s.  "
-			"Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
+	pr_info("Adding %uk swap on %s.  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" : "",