From b7c13218a682bc62cf6daf368ec2ae59073c86ce Mon Sep 17 00:00:00 2001
From: Rafael Aquini <aquini@redhat.com>
Date: Tue, 11 Dec 2012 16:02:31 -0800
Subject: [PATCH] --- yaml --- r: 338771 b: refs/heads/master c:
 78bd52097d04205a33a8014a1b8ac01cf1ae9d06 h: refs/heads/master i:   338769:
 9472e90f0e6a8ddd9157eec840f72cc54be985ce   338767:
 4e27648a8d9caaa8b39ce1e4ae3b1a0ec6252534 v: v3

---
 [refs]                        |  2 +-
 trunk/fs/hugetlbfs/inode.c    |  4 ++--
 trunk/include/linux/migrate.h |  7 +++++++
 trunk/mm/migrate.c            | 33 +++++++++++++++------------------
 4 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/[refs] b/[refs]
index 89d459843cb4..175bf259092a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 748ba883ba2818890a73461ef7dde1eed17ad89f
+refs/heads/master: 78bd52097d04205a33a8014a1b8ac01cf1ae9d06
diff --git a/trunk/fs/hugetlbfs/inode.c b/trunk/fs/hugetlbfs/inode.c
index 47e6e2f21e21..4a55f35a6ced 100644
--- a/trunk/fs/hugetlbfs/inode.c
+++ b/trunk/fs/hugetlbfs/inode.c
@@ -582,11 +582,11 @@ static int hugetlbfs_migrate_page(struct address_space *mapping,
 	int rc;
 
 	rc = migrate_huge_page_move_mapping(mapping, newpage, page);
-	if (rc)
+	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 	migrate_page_copy(newpage, page);
 
-	return 0;
+	return MIGRATEPAGE_SUCCESS;
 }
 
 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
diff --git a/trunk/include/linux/migrate.h b/trunk/include/linux/migrate.h
index ce7e6671968b..a4e886d17f87 100644
--- a/trunk/include/linux/migrate.h
+++ b/trunk/include/linux/migrate.h
@@ -7,6 +7,13 @@
 
 typedef struct page *new_page_t(struct page *, unsigned long private, int **);
 
+/*
+ * Return values from addresss_space_operations.migratepage():
+ * - negative errno on page migration failure;
+ * - zero on page migration success;
+ */
+#define MIGRATEPAGE_SUCCESS		0
+
 #ifdef CONFIG_MIGRATION
 
 extern void putback_lru_pages(struct list_head *l);
diff --git a/trunk/mm/migrate.c b/trunk/mm/migrate.c
index 1dc4598d2513..33f5f82a6006 100644
--- a/trunk/mm/migrate.c
+++ b/trunk/mm/migrate.c
@@ -276,7 +276,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
 		/* Anonymous page without mapping */
 		if (page_count(page) != 1)
 			return -EAGAIN;
-		return 0;
+		return MIGRATEPAGE_SUCCESS;
 	}
 
 	spin_lock_irq(&mapping->tree_lock);
@@ -346,7 +346,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
 	}
 	spin_unlock_irq(&mapping->tree_lock);
 
-	return 0;
+	return MIGRATEPAGE_SUCCESS;
 }
 
 /*
@@ -362,7 +362,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 	if (!mapping) {
 		if (page_count(page) != 1)
 			return -EAGAIN;
-		return 0;
+		return MIGRATEPAGE_SUCCESS;
 	}
 
 	spin_lock_irq(&mapping->tree_lock);
@@ -389,7 +389,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 	page_unfreeze_refs(page, expected_count - 1);
 
 	spin_unlock_irq(&mapping->tree_lock);
-	return 0;
+	return MIGRATEPAGE_SUCCESS;
 }
 
 /*
@@ -476,11 +476,11 @@ int migrate_page(struct address_space *mapping,
 
 	rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode);
 
-	if (rc)
+	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 
 	migrate_page_copy(newpage, page);
-	return 0;
+	return MIGRATEPAGE_SUCCESS;
 }
 EXPORT_SYMBOL(migrate_page);
 
@@ -503,7 +503,7 @@ int buffer_migrate_page(struct address_space *mapping,
 
 	rc = migrate_page_move_mapping(mapping, newpage, page, head, mode);
 
-	if (rc)
+	if (rc != MIGRATEPAGE_SUCCESS)
 		return rc;
 
 	/*
@@ -539,7 +539,7 @@ int buffer_migrate_page(struct address_space *mapping,
 
 	} while (bh != head);
 
-	return 0;
+	return MIGRATEPAGE_SUCCESS;
 }
 EXPORT_SYMBOL(buffer_migrate_page);
 #endif
@@ -618,7 +618,7 @@ static int fallback_migrate_page(struct address_space *mapping,
  *
  * Return value:
  *   < 0 - error code
- *  == 0 - success
+ *  MIGRATEPAGE_SUCCESS - success
  */
 static int move_to_new_page(struct page *newpage, struct page *page,
 				int remap_swapcache, enum migrate_mode mode)
@@ -655,7 +655,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
 	else
 		rc = fallback_migrate_page(mapping, newpage, page, mode);
 
-	if (rc) {
+	if (rc != MIGRATEPAGE_SUCCESS) {
 		newpage->mapping = NULL;
 	} else {
 		if (remap_swapcache)
@@ -804,7 +804,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		put_anon_vma(anon_vma);
 
 uncharge:
-	mem_cgroup_end_migration(mem, page, newpage, rc == 0);
+	mem_cgroup_end_migration(mem, page, newpage, rc == MIGRATEPAGE_SUCCESS);
 unlock:
 	unlock_page(page);
 out:
@@ -977,7 +977,7 @@ int migrate_pages(struct list_head *from,
 			case -EAGAIN:
 				retry++;
 				break;
-			case 0:
+			case MIGRATEPAGE_SUCCESS:
 				break;
 			default:
 				/* Permanent failure */
@@ -986,15 +986,12 @@ int migrate_pages(struct list_head *from,
 			}
 		}
 	}
-	rc = 0;
+	rc = nr_failed + retry;
 out:
 	if (!swapwrite)
 		current->flags &= ~PF_SWAPWRITE;
 
-	if (rc)
-		return rc;
-
-	return nr_failed + retry;
+	return rc;
 }
 
 int migrate_huge_page(struct page *hpage, new_page_t get_new_page,
@@ -1014,7 +1011,7 @@ int migrate_huge_page(struct page *hpage, new_page_t get_new_page,
 			/* try again */
 			cond_resched();
 			break;
-		case 0:
+		case MIGRATEPAGE_SUCCESS:
 			goto out;
 		default:
 			rc = -EIO;