1 files changed, 131 insertions, 17 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 5470e1cdf10c..5f90f0605b12 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1324,7 +1324,7 @@ static int flush_reservations(struct btrfs_fs_info *fs_info)
 	trans = btrfs_join_transaction(fs_info->tree_root);
 	if (IS_ERR(trans))
 		return PTR_ERR(trans);
-	btrfs_commit_transaction(trans);
+	ret = btrfs_commit_transaction(trans);
 
 	return ret;
 }
@@ -2505,8 +2505,8 @@ int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
 	struct extent_buffer *eb = root_eb;
 	struct btrfs_path *path = NULL;
 
-	BUG_ON(root_level < 0 || root_level >= BTRFS_MAX_LEVEL);
-	BUG_ON(root_eb == NULL);
+	ASSERT(0 <= root_level && root_level < BTRFS_MAX_LEVEL);
+	ASSERT(root_eb != NULL);
 
 	if (!btrfs_qgroup_full_accounting(fs_info))
 		return 0;
@@ -2861,8 +2861,6 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
 	if (nr_old_roots == 0 && nr_new_roots == 0)
 		goto out_free;
 
-	BUG_ON(!fs_info->quota_root);
-
 	trace_btrfs_qgroup_account_extent(fs_info, trans->transid, bytenr,
 					num_bytes, nr_old_roots, nr_new_roots);
 
@@ -2959,11 +2957,6 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans)
 				ctx.roots = NULL;
 			}
 
-			/* Free the reserved data space */
-			btrfs_qgroup_free_refroot(fs_info,
-					record->data_rsv_refroot,
-					record->data_rsv,
-					BTRFS_QGROUP_RSV_DATA);
 			/*
 			 * Use BTRFS_SEQ_LAST as time_seq to do special search,
 			 * which doesn't lock tree or delayed_refs and search
@@ -2987,6 +2980,11 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans)
 			record->old_roots = NULL;
 			new_roots = NULL;
 		}
+		/* Free the reserved data space */
+		btrfs_qgroup_free_refroot(fs_info,
+				record->data_rsv_refroot,
+				record->data_rsv,
+				BTRFS_QGROUP_RSV_DATA);
 cleanup:
 		ulist_free(record->old_roots);
 		ulist_free(new_roots);
@@ -3048,6 +3046,57 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans)
 	return ret;
 }
 
+int btrfs_qgroup_check_inherit(struct btrfs_fs_info *fs_info,
+			       struct btrfs_qgroup_inherit *inherit,
+			       size_t size)
+{
+	if (inherit->flags & ~BTRFS_QGROUP_INHERIT_FLAGS_SUPP)
+		return -EOPNOTSUPP;
+	if (size < sizeof(*inherit) || size > PAGE_SIZE)
+		return -EINVAL;
+
+	/*
+	 * In the past we allowed btrfs_qgroup_inherit to specify to copy
+	 * rfer/excl numbers directly from other qgroups.  This behavior has
+	 * been disabled in userspace for a very long time, but here we should
+	 * also disable it in kernel, as this behavior is known to mark qgroup
+	 * inconsistent, and a rescan would wipe out the changes anyway.
+	 *
+	 * Reject any btrfs_qgroup_inherit with num_ref_copies or num_excl_copies.
+	 */
+	if (inherit->num_ref_copies > 0 || inherit->num_excl_copies > 0)
+		return -EINVAL;
+
+	if (inherit->num_qgroups > PAGE_SIZE)
+		return -EINVAL;
+
+	if (size != struct_size(inherit, qgroups, inherit->num_qgroups))
+		return -EINVAL;
+
+	/*
+	 * Now check all the remaining qgroups, they should all:
+	 *
+	 * - Exist
+	 * - Be higher level qgroups.
+	 */
+	for (int i = 0; i < inherit->num_qgroups; i++) {
+		struct btrfs_qgroup *qgroup;
+		u64 qgroupid = inherit->qgroups[i];
+
+		if (btrfs_qgroup_level(qgroupid) == 0)
+			return -EINVAL;
+
+		spin_lock(&fs_info->qgroup_lock);
+		qgroup = find_qgroup_rb(fs_info, qgroupid);
+		if (!qgroup) {
+			spin_unlock(&fs_info->qgroup_lock);
+			return -ENOENT;
+		}
+		spin_unlock(&fs_info->qgroup_lock);
+	}
+	return 0;
+}
+
 static int qgroup_auto_inherit(struct btrfs_fs_info *fs_info,
 			       u64 inode_rootid,
 			       struct btrfs_qgroup_inherit **inherit)
@@ -3090,6 +3139,62 @@ static int qgroup_auto_inherit(struct btrfs_fs_info *fs_info,
 }
 
 /*
+ * Check if we can skip rescan when inheriting qgroups.  If @src has a single
+ * @parent, and that @parent is owning all its bytes exclusively, we can skip
+ * the full rescan, by just adding nodesize to the @parent's excl/rfer.
+ *
+ * Return <0 for fatal errors (like srcid/parentid has no qgroup).
+ * Return 0 if a quick inherit is done.
+ * Return >0 if a quick inherit is not possible, and a full rescan is needed.
+ */
+static int qgroup_snapshot_quick_inherit(struct btrfs_fs_info *fs_info,
+					 u64 srcid, u64 parentid)
+{
+	struct btrfs_qgroup *src;
+	struct btrfs_qgroup *parent;
+	struct btrfs_qgroup_list *list;
+	int nr_parents = 0;
+
+	src = find_qgroup_rb(fs_info, srcid);
+	if (!src)
+		return -ENOENT;
+	parent = find_qgroup_rb(fs_info, parentid);
+	if (!parent)
+		return -ENOENT;
+
+	/*
+	 * Source has no parent qgroup, but our new qgroup would have one.
+	 * Qgroup numbers would become inconsistent.
+	 */
+	if (list_empty(&src->groups))
+		return 1;
+
+	list_for_each_entry(list, &src->groups, next_group) {
+		/* The parent is not the same, quick update is not possible. */
+		if (list->group->qgroupid != parentid)
+			return 1;
+		nr_parents++;
+		/*
+		 * More than one parent qgroup, we can't be sure about accounting
+		 * consistency.
+		 */
+		if (nr_parents > 1)
+			return 1;
+	}
+
+	/*
+	 * The parent is not exclusively owning all its bytes.  We're not sure
+	 * if the source has any bytes not fully owned by the parent.
+	 */
+	if (parent->excl != parent->rfer)
+		return 1;
+
+	parent->excl += fs_info->nodesize;
+	parent->rfer += fs_info->nodesize;
+	return 0;
+}
+
+/*
  * Copy the accounting information between qgroups. This is necessary
  * when a snapshot or a subvolume is created. Throwing an error will
  * cause a transaction abort so we take extra care here to only error
@@ -3257,6 +3362,13 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 
 		qgroup_dirty(fs_info, dstgroup);
 		qgroup_dirty(fs_info, srcgroup);
+
+		/*
+		 * If the source qgroup has parent but the new one doesn't,
+		 * we need a full rescan.
+		 */
+		if (!inherit && !list_empty(&srcgroup->groups))
+			need_rescan = true;
 	}
 
 	if (!inherit)
@@ -3271,14 +3383,16 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 			if (ret)
 				goto unlock;
 		}
+		if (srcid) {
+			/* Check if we can do a quick inherit. */
+			ret = qgroup_snapshot_quick_inherit(fs_info, srcid, *i_qgroups);
+			if (ret < 0)
+				goto unlock;
+			if (ret > 0)
+				need_rescan = true;
+			ret = 0;
+		}
 		++i_qgroups;
-
-		/*
-		 * If we're doing a snapshot, and adding the snapshot to a new
-		 * qgroup, the numbers are guaranteed to be incorrect.
-		 */
-		if (srcid)
-			need_rescan = true;
 	}
 
 	for (i = 0; i <  inherit->num_ref_copies; ++i, i_qgroups += 2) {