1 files changed, 34 insertions, 11 deletions

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 481802efaa14..e8bc37453336 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -228,7 +228,7 @@ int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 	if (!num_bytes)
 		return 0;
 
-	ret = btrfs_reserve_metadata_bytes(fs_info, space_info, num_bytes, flush);
+	ret = btrfs_reserve_metadata_bytes(space_info, num_bytes, flush);
 	if (ret)
 		return ret;
 
@@ -798,9 +798,13 @@ static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
 }
 
 /*
- * helper function to actually insert a head node into the rbtree.
- * this does all the dirty work in terms of maintaining the correct
- * overall modification count.
+ * Helper function to actually insert a head node into the xarray. This does all
+ * the dirty work in terms of maintaining the correct overall modification
+ * count.
+ *
+ * The caller is responsible for calling kfree() on @qrecord. More specifically,
+ * if this function reports that it did not insert it as noted in
+ * @qrecord_inserted_ret, then it's safe to call kfree() on it.
  *
  * Returns an error pointer in case of an error.
  */
@@ -814,7 +818,14 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans,
 	struct btrfs_delayed_ref_head *existing;
 	struct btrfs_delayed_ref_root *delayed_refs;
 	const unsigned long index = (head_ref->bytenr >> fs_info->sectorsize_bits);
-	bool qrecord_inserted = false;
+
+	/*
+	 * If 'qrecord_inserted_ret' is provided, then the first thing we need
+	 * to do is to initialize it to false just in case we have an exit
+	 * before trying to insert the record.
+	 */
+	if (qrecord_inserted_ret)
+		*qrecord_inserted_ret = false;
 
 	delayed_refs = &trans->transaction->delayed_refs;
 	lockdep_assert_held(&delayed_refs->lock);
@@ -833,6 +844,12 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans,
 
 	/* Record qgroup extent info if provided */
 	if (qrecord) {
+		/*
+		 * Setting 'qrecord' but not 'qrecord_inserted_ret' will likely
+		 * result in a memory leakage.
+		 */
+		ASSERT(qrecord_inserted_ret != NULL);
+
 		int ret;
 
 		ret = btrfs_qgroup_trace_extent_nolock(fs_info, delayed_refs, qrecord,
@@ -840,12 +857,10 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans,
 		if (ret) {
 			/* Clean up if insertion fails or item exists. */
 			xa_release(&delayed_refs->dirty_extents, index);
-			/* Caller responsible for freeing qrecord on error. */
 			if (ret < 0)
 				return ERR_PTR(ret);
-			kfree(qrecord);
-		} else {
-			qrecord_inserted = true;
+		} else if (qrecord_inserted_ret) {
+			*qrecord_inserted_ret = true;
 		}
 	}
 
@@ -888,8 +903,6 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans,
 		delayed_refs->num_heads++;
 		delayed_refs->num_heads_ready++;
 	}
-	if (qrecord_inserted_ret)
-		*qrecord_inserted_ret = qrecord_inserted;
 
 	return head_ref;
 }
@@ -1049,6 +1062,14 @@ static int add_delayed_ref(struct btrfs_trans_handle *trans,
 		xa_release(&delayed_refs->head_refs, index);
 		spin_unlock(&delayed_refs->lock);
 		ret = PTR_ERR(new_head_ref);
+
+		/*
+		 * It's only safe to call kfree() on 'qrecord' if
+		 * add_delayed_ref_head() has _not_ inserted it for
+		 * tracing. Otherwise we need to handle this here.
+		 */
+		if (!qrecord_reserved || qrecord_inserted)
+			goto free_head_ref;
 		goto free_record;
 	}
 	head_ref = new_head_ref;
@@ -1071,6 +1092,8 @@ static int add_delayed_ref(struct btrfs_trans_handle *trans,
 
 	if (qrecord_inserted)
 		return btrfs_qgroup_trace_extent_post(trans, record, generic_ref->bytenr);
+
+	kfree(record);
 	return 0;
 
 free_record: