Btrfs: fix memory leaks on walking backrefs failure

When walking backrefs, we may iterate every inode's extent
and add/merge them into ulist, and the caller will free memory
from ulist.

However, if we fail to allocate inode's extents element
memory or ulist_add() fail to allocate memory, we won't
add allocated memory into ulist, and the caller won't
free some allocated memory thus memory leaks happen.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 18 insertions, 7 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7966acd5dc7f..aded3ef3d3d4 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -66,6 +66,16 @@ static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
         return 0;
 }
 
+static void free_inode_elem_list(struct extent_inode_elem *eie)
+{
+        struct extent_inode_elem *eie_next;
+
+        for (; eie; eie = eie_next) {
+                eie_next = eie->next;
+                kfree(eie);
+        }
+}
+
 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
                                 u64 extent_item_pos,
                                 struct extent_inode_elem **eie)
@@ -275,6 +285,7 @@ static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
                                         old = old->next;
                                 old->next = eie;
                         }
+                        eie = NULL;
                 }
 next:
                 ret = btrfs_next_old_item(root, path, time_seq);
@@ -282,6 +293,8 @@ next:
 
         if (ret > 0)
                 ret = 0;
+        else if (ret < 0)
+                free_inode_elem_list(eie);
         return ret;
 }
 
@@ -845,6 +858,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
         struct list_head prefs_delayed;
         struct list_head prefs;
         struct __prelim_ref *ref;
+        struct extent_inode_elem *eie = NULL;
 
         INIT_LIST_HEAD(&prefs);
         INIT_LIST_HEAD(&prefs_delayed);
@@ -958,7 +972,6 @@ again:
                                 goto out;
                 }
                 if (ref->count && ref->parent) {
-                        struct extent_inode_elem *eie = NULL;
                         if (extent_item_pos && !ref->inode_list) {
                                 u32 bsz;
                                 struct extent_buffer *eb;
@@ -993,6 +1006,7 @@ again:
                                         eie = eie->next;
                                 eie->next = ref->inode_list;
                         }
+                        eie = NULL;
                 }
                 list_del(&ref->list);
                 kmem_cache_free(btrfs_prelim_ref_cache, ref);
@@ -1011,7 +1025,8 @@ out:
                 list_del(&ref->list);
                 kmem_cache_free(btrfs_prelim_ref_cache, ref);
         }
-
+        if (ret < 0)
+                free_inode_elem_list(eie);
         return ret;
 }
 
@@ -1019,7 +1034,6 @@ static void free_leaf_list(struct ulist *blocks)
 {
         struct ulist_node *node = NULL;
         struct extent_inode_elem *eie;
-        struct extent_inode_elem *eie_next;
         struct ulist_iterator uiter;
 
         ULIST_ITER_INIT(&uiter);
@@ -1027,10 +1041,7 @@ static void free_leaf_list(struct ulist *blocks)
                 if (!node->aux)
                         continue;
                 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
-                for (; eie; eie = eie_next) {
-                        eie_next = eie->next;
-                        kfree(eie);
-                }
+                free_inode_elem_list(eie);
                 node->aux = 0;
         }