This patch introduces MIGRATEPAGE_SUCCESS as the default return code
for address_space_operations.migratepage() method and documents the
expected return code for the same method in failure cases.
Signed-off-by: Rafael Aquini <aqu...@redhat.com>
---
fs/hugetlbfs/inode.c | 4 ++--
include/linux/migrate.h | 7 +++++++
mm/migrate.c | 33 +++++++++++++++------------------
3 files changed, 24 insertions(+), 20 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 14bc0c1..fed1cd5 100644
--- a/fs/hugetlbfs/inode.c
+++ b/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/include/linux/migrate.h b/include/linux/migrate.h
index 9a5afea..fab15ae 100644
--- a/include/linux/migrate.h
+++ b/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/mm/migrate.c b/mm/migrate.c
index 0c5ec37..6f408c7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -286,7 +286,7 @@ static int migrate_page_move_mapping(struct address_space
*mapping,
expected_count += 1;
if (page_count(page) != expected_count)
return -EAGAIN;
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
spin_lock_irq(&mapping->tree_lock);
@@ -356,7 +356,7 @@ static int migrate_page_move_mapping(struct address_space
*mapping,
}
spin_unlock_irq(&mapping->tree_lock);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
/*
@@ -372,7 +372,7 @@ 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);
@@ -399,7 +399,7 @@ 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;
}
/*
@@ -486,11 +486,11 @@ 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);
@@ -513,7 +513,7 @@ 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;
/*
@@ -549,7 +549,7 @@ int buffer_migrate_page(struct address_space *mapping,
} while (bh != head);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL(buffer_migrate_page);
#endif
@@ -628,7 +628,7 @@ 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)
@@ -665,7 +665,7 @@ 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)
@@ -814,7 +814,7 @@ skip_unmap:
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:
@@ -987,7 +987,7 @@ int migrate_pages(struct list_head *from,
case -EAGAIN:
retry++;
break;
- case 0:
+ case MIGRATEPAGE_SUCCESS:
break;
default:
/* Permanent failure */
@@ -996,15 +996,12 @@ 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,
@@ -1024,7 +1021,7 @@ 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;
--
1.7.11.7
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