1 files changed, 48 insertions, 34 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 3fe15d6f4..a1eb573fb 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -136,6 +136,7 @@ struct share_check {
 	u64 root_objectid;
 	u64 inum;
 	int share_count;
+	bool have_delayed_delete_refs;
 };
 
 static inline int extent_is_shared(struct share_check *sc)
@@ -588,6 +589,18 @@ unode_aux_to_inode_list(struct ulist_node *node)
 	return (struct extent_inode_elem *)(uintptr_t)node->aux;
 }
 
+static void free_leaf_list(struct ulist *ulist)
+{
+	struct ulist_node *node;
+	struct ulist_iterator uiter;
+
+	ULIST_ITER_INIT(&uiter);
+	while ((node = ulist_next(ulist, &uiter)))
+		free_inode_elem_list(unode_aux_to_inode_list(node));
+
+	ulist_free(ulist);
+}
+
 /*
  * We maintain three seperate rbtrees: one for direct refs, one for
  * indirect refs which have a key, and one for indirect refs which do not
@@ -702,7 +715,11 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
 		cond_resched();
 	}
 out:
-	ulist_free(parents);
+	/*
+	 * We may have inode lists attached to refs in the parents ulist, so we
+	 * must free them before freeing the ulist and its refs.
+	 */
+	free_leaf_list(parents);
 	return ret;
 }
 
@@ -760,16 +777,11 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
 			    struct share_check *sc)
 {
 	struct btrfs_delayed_ref_node *node;
-	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
 	struct btrfs_key key;
-	struct btrfs_key tmp_op_key;
 	struct rb_node *n;
 	int count;
 	int ret = 0;
 
-	if (extent_op && extent_op->update_key)
-		btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
-
 	spin_lock(&head->lock);
 	for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) {
 		node = rb_entry(n, struct btrfs_delayed_ref_node,
@@ -796,10 +808,16 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
 		case BTRFS_TREE_BLOCK_REF_KEY: {
 			/* NORMAL INDIRECT METADATA backref */
 			struct btrfs_delayed_tree_ref *ref;
+			struct btrfs_key *key_ptr = NULL;
+
+			if (head->extent_op && head->extent_op->update_key) {
+				btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
+				key_ptr = &key;
+			}
 
 			ref = btrfs_delayed_node_to_tree_ref(node);
 			ret = add_indirect_ref(fs_info, preftrees, ref->root,
-					       &tmp_op_key, ref->level + 1,
+					       key_ptr, ref->level + 1,
 					       node->bytenr, count, sc,
 					       GFP_ATOMIC);
 			break;
@@ -825,13 +843,22 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
 			key.offset = ref->offset;
 
 			/*
-			 * Found a inum that doesn't match our known inum, we
-			 * know it's shared.
+			 * If we have a share check context and a reference for
+			 * another inode, we can't exit immediately. This is
+			 * because even if this is a BTRFS_ADD_DELAYED_REF
+			 * reference we may find next a BTRFS_DROP_DELAYED_REF
+			 * which cancels out this ADD reference.
+			 *
+			 * If this is a DROP reference and there was no previous
+			 * ADD reference, then we need to signal that when we
+			 * process references from the extent tree (through
+			 * add_inline_refs() and add_keyed_refs()), we should
+			 * not exit early if we find a reference for another
+			 * inode, because one of the delayed DROP references
+			 * may cancel that reference in the extent tree.
 			 */
-			if (sc && sc->inum && ref->objectid != sc->inum) {
-				ret = BACKREF_FOUND_SHARED;
-				goto out;
-			}
+			if (sc && count < 0)
+				sc->have_delayed_delete_refs = true;
 
 			ret = add_indirect_ref(fs_info, preftrees, ref->root,
 					       &key, 0, node->bytenr, count, sc,
@@ -861,7 +888,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
 	}
 	if (!ret)
 		ret = extent_is_shared(sc);
-out:
+
 	spin_unlock(&head->lock);
 	return ret;
 }
@@ -965,7 +992,8 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
 			key.type = BTRFS_EXTENT_DATA_KEY;
 			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 
-			if (sc && sc->inum && key.objectid != sc->inum) {
+			if (sc && sc->inum && key.objectid != sc->inum &&
+			    !sc->have_delayed_delete_refs) {
 				ret = BACKREF_FOUND_SHARED;
 				break;
 			}
@@ -975,6 +1003,7 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
 			ret = add_indirect_ref(fs_info, preftrees, root,
 					       &key, 0, bytenr, count,
 					       sc, GFP_NOFS);
+
 			break;
 		}
 		default:
@@ -1064,7 +1093,8 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
 			key.type = BTRFS_EXTENT_DATA_KEY;
 			key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 
-			if (sc && sc->inum && key.objectid != sc->inum) {
+			if (sc && sc->inum && key.objectid != sc->inum &&
+			    !sc->have_delayed_delete_refs) {
 				ret = BACKREF_FOUND_SHARED;
 				break;
 			}
@@ -1346,24 +1376,6 @@ out:
 	return ret;
 }
 
-static void free_leaf_list(struct ulist *blocks)
-{
-	struct ulist_node *node = NULL;
-	struct extent_inode_elem *eie;
-	struct ulist_iterator uiter;
-
-	ULIST_ITER_INIT(&uiter);
-	while ((node = ulist_next(blocks, &uiter))) {
-		if (!node->aux)
-			continue;
-		eie = unode_aux_to_inode_list(node);
-		free_inode_elem_list(eie);
-		node->aux = 0;
-	}
-
-	ulist_free(blocks);
-}
-
 /*
  * Finds all leafs with a reference to the specified combination of bytenr and
  * offset. key_list_head will point to a list of corresponding keys (caller must
@@ -1490,6 +1502,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
 		.root_objectid = root->objectid,
 		.inum = inum,
 		.share_count = 0,
+		.have_delayed_delete_refs = false,
 	};
 
 	tmp = ulist_alloc(GFP_NOFS);
@@ -1528,6 +1541,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
 			break;
 		bytenr = node->val;
 		shared.share_count = 0;
+		shared.have_delayed_delete_refs = false;
 		cond_resched();
 	}