1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2016 Oracle.  All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 */
6#ifndef	__XFS_REFCOUNT_ITEM_H__
7#define	__XFS_REFCOUNT_ITEM_H__
8
9/*
10 * There are (currently) two pairs of refcount btree redo item types:
11 * increase and decrease.  The log items for these are CUI (refcount
12 * update intent) and CUD (refcount update done).  The redo item type
13 * is encoded in the flags field of each xfs_map_extent.
14 *
15 * *I items should be recorded in the *first* of a series of rolled
16 * transactions, and the *D items should be recorded in the same
17 * transaction that records the associated refcountbt updates.
18 *
19 * Should the system crash after the commit of the first transaction
20 * but before the commit of the final transaction in a series, log
21 * recovery will use the redo information recorded by the intent items
22 * to replay the refcountbt metadata updates.
23 */
24
25/* kernel only CUI/CUD definitions */
26
27struct xfs_mount;
28struct kmem_cache;
29
30/*
31 * Max number of extents in fast allocation path.
32 */
33#define	XFS_CUI_MAX_FAST_EXTENTS	16
34
35/*
36 * This is the "refcount update intent" log item.  It is used to log
37 * the fact that some reverse mappings need to change.  It is used in
38 * conjunction with the "refcount update done" log item described
39 * below.
40 *
41 * These log items follow the same rules as struct xfs_efi_log_item;
42 * see the comments about that structure (in xfs_extfree_item.h) for
43 * more details.
44 */
45struct xfs_cui_log_item {
46	struct xfs_log_item		cui_item;
47	atomic_t			cui_refcount;
48	atomic_t			cui_next_extent;
49	struct xfs_cui_log_format	cui_format;
50};
51
52static inline size_t
53xfs_cui_log_item_sizeof(
54	unsigned int		nr)
55{
56	return offsetof(struct xfs_cui_log_item, cui_format) +
57			xfs_cui_log_format_sizeof(nr);
58}
59
60/*
61 * This is the "refcount update done" log item.  It is used to log the
62 * fact that some refcountbt updates mentioned in an earlier cui item
63 * have been performed.
64 */
65struct xfs_cud_log_item {
66	struct xfs_log_item		cud_item;
67	struct xfs_cui_log_item		*cud_cuip;
68	struct xfs_cud_log_format	cud_format;
69};
70
71extern struct kmem_cache	*xfs_cui_cache;
72extern struct kmem_cache	*xfs_cud_cache;
73
74#endif	/* __XFS_REFCOUNT_ITEM_H__ */
75