1 files changed, 37 insertions, 21 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 35443cc4b9a9..42491d728e99 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -38,19 +38,12 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                    struct btrfs_path *path, int level, int slot);
 
-inline void btrfs_init_path(struct btrfs_path *p)
-{
-        memset(p, 0, sizeof(*p));
-}
-
 struct btrfs_path *btrfs_alloc_path(void)
 {
         struct btrfs_path *path;
-        path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
-        if (path) {
-                btrfs_init_path(path);
+        path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
+        if (path)
                 path->reada = 1;
-        }
         return path;
 }
 
@@ -69,14 +62,38 @@ noinline void btrfs_set_path_blocking(struct btrfs_path *p)
 
 /*
  * reset all the locked nodes in the patch to spinning locks.
+ *
+ * held is used to keep lockdep happy, when lockdep is enabled
+ * we set held to a blocking lock before we go around and
+ * retake all the spinlocks in the path.  You can safely use NULL
+ * for held
  */
-noinline void btrfs_clear_path_blocking(struct btrfs_path *p)
+noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
+                                        struct extent_buffer *held)
 {
         int i;
-        for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        /* lockdep really cares that we take all of these spinlocks
+         * in the right order.  If any of the locks in the path are not
+         * currently blocking, it is going to complain.  So, make really
+         * really sure by forcing the path to blocking before we clear
+         * the path blocking.
+         */
+        if (held)
+                btrfs_set_lock_blocking(held);
+        btrfs_set_path_blocking(p);
+#endif
+
+        for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
                 if (p->nodes[i] && p->locks[i])
                         btrfs_clear_lock_blocking(p->nodes[i]);
         }
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        if (held)
+                btrfs_clear_lock_blocking(held);
+#endif
 }
 
 /* this also releases the path */
@@ -286,7 +303,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                                                   trans->transid, level, &ins);
                 BUG_ON(ret);
                 cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
-                                            buf->len);
+                                            buf->len, level);
         } else {
                 cow = btrfs_alloc_free_block(trans, root, buf->len,
                                              parent_start,
@@ -917,9 +934,9 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 
                 /* promote the child to a root */
                 child = read_node_slot(root, mid, 0);
+                BUG_ON(!child);
                 btrfs_tree_lock(child);
                 btrfs_set_lock_blocking(child);
-                BUG_ON(!child);
                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0);
                 BUG_ON(ret);
 
@@ -1566,7 +1583,7 @@ cow_done:
                 if (!p->skip_locking)
                         p->locks[level] = 1;
 
-                btrfs_clear_path_blocking(p);
+                btrfs_clear_path_blocking(p, NULL);
 
                 /*
                  * we have a lock on b and as long as we aren't changing
@@ -1605,7 +1622,7 @@ cow_done:
 
                                 btrfs_set_path_blocking(p);
                                 sret = split_node(trans, root, p, level);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 BUG_ON(sret > 0);
                                 if (sret) {
@@ -1625,7 +1642,7 @@ cow_done:
 
                                 btrfs_set_path_blocking(p);
                                 sret = balance_level(trans, root, p, level);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 if (sret) {
                                         ret = sret;
@@ -1688,13 +1705,13 @@ cow_done:
                         if (!p->skip_locking) {
                                 int lret;
 
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
                                 lret = btrfs_try_spin_lock(b);
 
                                 if (!lret) {
                                         btrfs_set_path_blocking(p);
                                         btrfs_tree_lock(b);
-                                        btrfs_clear_path_blocking(p);
+                                        btrfs_clear_path_blocking(p, b);
                                 }
                         }
                 } else {
@@ -1706,7 +1723,7 @@ cow_done:
                                 btrfs_set_path_blocking(p);
                                 sret = split_leaf(trans, root, key,
                                                       p, ins_len, ret == 0);
-                                btrfs_clear_path_blocking(p);
+                                btrfs_clear_path_blocking(p, NULL);
 
                                 BUG_ON(sret > 0);
                                 if (sret) {
@@ -3926,7 +3943,6 @@ find_next_key:
                                 btrfs_release_path(root, path);
                                 goto again;
                         } else {
-                                btrfs_clear_path_blocking(path);
                                 goto out;
                         }
                 }
@@ -3946,7 +3962,7 @@ find_next_key:
                 path->locks[level - 1] = 1;
                 path->nodes[level - 1] = cur;
                 unlock_up(path, level, 1);
-                btrfs_clear_path_blocking(path);
+                btrfs_clear_path_blocking(path, NULL);
         }
 out:
         if (ret == 0)