X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fswapfile.c;h=4de7f02f820b03bfcf36b5fc8d6827b5eecd38cb;hb=6ea529a2037ce662fc6bfa572b46d47407d08805;hp=0d7296971ad955318a369123d759ae41e90ee97f;hpb=355cfa73ddff2fb8fa14e93bd94a057cc022512e;p=safe%2Fjmp%2Flinux-2.6

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0d72969..4de7f02 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -79,6 +79,32 @@ static inline unsigned short encode_swapmap(int count, bool has_cache)
 	return ret;
 }
 
+/* returnes 1 if swap entry is freed */
+static int
+__try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
+{
+	int type = si - swap_info;
+	swp_entry_t entry = swp_entry(type, offset);
+	struct page *page;
+	int ret = 0;
+
+	page = find_get_page(&swapper_space, entry.val);
+	if (!page)
+		return 0;
+	/*
+	 * This function is called from scan_swap_map() and it's called
+	 * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here.
+	 * We have to use trylock for avoiding deadlock. This is a special
+	 * case and you should use try_to_free_swap() with explicit lock_page()
+	 * in usual operations.
+	 */
+	if (trylock_page(page)) {
+		ret = try_to_free_swap(page);
+		unlock_page(page);
+	}
+	page_cache_release(page);
+	return ret;
+}
 
 /*
  * We need this because the bdev->unplug_fn can sleep and we cannot
@@ -135,7 +161,8 @@ static int discard_swap(struct swap_info_struct *si)
 		}
 
 		err = blkdev_issue_discard(si->bdev, start_block,
-						nr_blocks, GFP_KERNEL);
+						nr_blocks, GFP_KERNEL,
+						DISCARD_FL_BARRIER);
 		if (err)
 			break;
 
@@ -174,7 +201,8 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 			start_block <<= PAGE_SHIFT - 9;
 			nr_blocks <<= PAGE_SHIFT - 9;
 			if (blkdev_issue_discard(si->bdev, start_block,
-							nr_blocks, GFP_NOIO))
+							nr_blocks, GFP_NOIO,
+							DISCARD_FL_BARRIER))
 				break;
 		}
 
@@ -301,6 +329,19 @@ checks:
 		goto no_page;
 	if (offset > si->highest_bit)
 		scan_base = offset = si->lowest_bit;
+
+	/* reuse swap entry of cache-only swap if not busy. */
+	if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+		int swap_was_freed;
+		spin_unlock(&swap_lock);
+		swap_was_freed = __try_to_reclaim_swap(si, offset);
+		spin_lock(&swap_lock);
+		/* entry was freed successfully, try to use this again */
+		if (swap_was_freed)
+			goto checks;
+		goto scan; /* check next one */
+	}
+
 	if (si->swap_map[offset])
 		goto scan;
 
@@ -382,6 +423,10 @@ scan:
 			spin_lock(&swap_lock);
 			goto checks;
 		}
+		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+			spin_lock(&swap_lock);
+			goto checks;
+		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
@@ -393,6 +438,10 @@ scan:
 			spin_lock(&swap_lock);
 			goto checks;
 		}
+		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+			spin_lock(&swap_lock);
+			goto checks;
+		}
 		if (unlikely(--latency_ration < 0)) {
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
@@ -536,8 +585,9 @@ static int swap_entry_free(struct swap_info_struct *p,
 			swap_list.next = p - swap_info;
 		nr_swap_pages++;
 		p->inuse_pages--;
-		mem_cgroup_uncharge_swap(ent);
 	}
+	if (!swap_count(count))
+		mem_cgroup_uncharge_swap(ent);
 	return count;
 }
 
@@ -562,12 +612,19 @@ void swap_free(swp_entry_t entry)
 void swapcache_free(swp_entry_t entry, struct page *page)
 {
 	struct swap_info_struct *p;
+	int ret;
 
-	if (page)
-		mem_cgroup_uncharge_swapcache(page, entry);
 	p = swap_info_get(entry);
 	if (p) {
-		swap_entry_free(p, entry, SWAP_CACHE);
+		ret = swap_entry_free(p, entry, SWAP_CACHE);
+		if (page) {
+			bool swapout;
+			if (ret)
+				swapout = true; /* the end of swap out */
+			else
+				swapout = false; /* no more swap users! */
+			mem_cgroup_uncharge_swapcache(page, entry, swapout);
+		}
 		spin_unlock(&swap_lock);
 	}
 	return;
@@ -642,7 +699,7 @@ int free_swap_and_cache(swp_entry_t entry)
 	struct swap_info_struct *p;
 	struct page *page = NULL;
 
-	if (is_migration_entry(entry))
+	if (non_swap_entry(entry))
 		return 1;
 
 	p = swap_info_get(entry);
@@ -698,7 +755,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
 
 		if (!bdev) {
 			if (bdev_p)
-				*bdev_p = bdget(sis->bdev->bd_dev);
+				*bdev_p = bdgrab(sis->bdev);
 
 			spin_unlock(&swap_lock);
 			return i;
@@ -710,7 +767,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
 					struct swap_extent, list);
 			if (se->start_block == offset) {
 				if (bdev_p)
-					*bdev_p = bdget(sis->bdev->bd_dev);
+					*bdev_p = bdgrab(sis->bdev);
 
 				spin_unlock(&swap_lock);
 				bdput(bdev);
@@ -1518,9 +1575,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	p->flags &= ~SWP_WRITEOK;
 	spin_unlock(&swap_lock);
 
-	current->flags |= PF_SWAPOFF;
+	current->flags |= PF_OOM_ORIGIN;
 	err = try_to_unuse(type);
-	current->flags &= ~PF_SWAPOFF;
+	current->flags &= ~PF_OOM_ORIGIN;
 
 	if (err) {
 		/* re-insert swap space back into swap_list */
@@ -2028,7 +2085,7 @@ static int __swap_duplicate(swp_entry_t entry, bool cache)
 	int count;
 	bool has_cache;
 
-	if (is_migration_entry(entry))
+	if (non_swap_entry(entry))
 		return -EINVAL;
 
 	type = swp_type(entry);