1 files changed, 17 insertions, 8 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index e4054e533f6d..571024bc632e 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -170,7 +170,7 @@ int __init btrfs_prelim_ref_init(void)
 	return 0;
 }
 
-void btrfs_prelim_ref_exit(void)
+void __cold btrfs_prelim_ref_exit(void)
 {
 	kmem_cache_destroy(btrfs_prelim_ref_cache);
 }
@@ -738,7 +738,8 @@ static int add_missing_keys(struct btrfs_fs_info *fs_info,
 		BUG_ON(ref->key_for_search.type);
 		BUG_ON(!ref->wanted_disk_byte);
 
-		eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0);
+		eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0,
+				     ref->level - 1, NULL);
 		if (IS_ERR(eb)) {
 			free_pref(ref);
 			return PTR_ERR(eb);
@@ -773,15 +774,12 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
 	struct btrfs_delayed_extent_op *extent_op = head->extent_op;
 	struct btrfs_key key;
 	struct btrfs_key tmp_op_key;
-	struct btrfs_key *op_key = NULL;
 	struct rb_node *n;
 	int count;
 	int ret = 0;
 
-	if (extent_op && extent_op->update_key) {
+	if (extent_op && extent_op->update_key)
 		btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);
-		op_key = &tmp_op_key;
-	}
 
 	spin_lock(&head->lock);
 	for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) {
@@ -1264,7 +1262,16 @@ again:
 	while (node) {
 		ref = rb_entry(node, struct prelim_ref, rbnode);
 		node = rb_next(&ref->rbnode);
-		WARN_ON(ref->count < 0);
+		/*
+		 * ref->count < 0 can happen here if there are delayed
+		 * refs with a node->action of BTRFS_DROP_DELAYED_REF.
+		 * prelim_ref_insert() relies on this when merging
+		 * identical refs to keep the overall count correct.
+		 * prelim_ref_insert() will merge only those refs
+		 * which compare identically.  Any refs having
+		 * e.g. different offsets would not be merged,
+		 * and would retain their original ref->count < 0.
+		 */
 		if (roots && ref->count && ref->root_id && ref->parent == 0) {
 			if (sc && sc->root_objectid &&
 			    ref->root_id != sc->root_objectid) {
@@ -1282,7 +1289,8 @@ again:
 			    ref->level == 0) {
 				struct extent_buffer *eb;
 
-				eb = read_tree_block(fs_info, ref->parent, 0);
+				eb = read_tree_block(fs_info, ref->parent, 0,
+						     ref->level, NULL);
 				if (IS_ERR(eb)) {
 					ret = PTR_ERR(eb);
 					goto out;
@@ -1510,6 +1518,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
 		if (!node)
 			break;
 		bytenr = node->val;
+		shared.share_count = 0;
 		cond_resched();
 	}