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_BMAP_ITEM_H__
7  #define	__XFS_BMAP_ITEM_H__
8  
9  /*
10   * There are (currently) two pairs of bmap btree redo item types: map & unmap.
11   * The common abbreviations for these are BUI (bmap update intent) and BUD
12   * (bmap update done).  The redo item type is encoded in the flags field of
13   * 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 transaction
17   * that records the associated bmbt updates.
18   *
19   * Should the system crash after the commit of the first transaction but
20   * before the commit of the final transaction in a series, log recovery will
21   * use the redo information recorded by the intent items to replay the
22   * bmbt metadata updates in the non-first transaction.
23   */
24  
25  /* kernel only BUI/BUD definitions */
26  
27  struct xfs_mount;
28  struct kmem_cache;
29  
30  /*
31   * Max number of extents in fast allocation path.
32   */
33  #define	XFS_BUI_MAX_FAST_EXTENTS	1
34  
35  /*
36   * This is the "bmap update intent" log item.  It is used to log the fact that
37   * some reverse mappings need to change.  It is used in conjunction with the
38   * "bmap update done" log item described below.
39   *
40   * These log items follow the same rules as struct xfs_efi_log_item; see the
41   * comments about that structure (in xfs_extfree_item.h) for more details.
42   */
43  struct xfs_bui_log_item {
44  	struct xfs_log_item		bui_item;
45  	atomic_t			bui_refcount;
46  	atomic_t			bui_next_extent;
47  	struct xfs_bui_log_format	bui_format;
48  };
49  
50  static inline size_t
xfs_bui_log_item_sizeof(unsigned int nr)51  xfs_bui_log_item_sizeof(
52  	unsigned int		nr)
53  {
54  	return offsetof(struct xfs_bui_log_item, bui_format) +
55  			xfs_bui_log_format_sizeof(nr);
56  }
57  
58  /*
59   * This is the "bmap update done" log item.  It is used to log the fact that
60   * some bmbt updates mentioned in an earlier bui item have been performed.
61   */
62  struct xfs_bud_log_item {
63  	struct xfs_log_item		bud_item;
64  	struct xfs_bui_log_item		*bud_buip;
65  	struct xfs_bud_log_format	bud_format;
66  };
67  
68  extern struct kmem_cache	*xfs_bui_cache;
69  extern struct kmem_cache	*xfs_bud_cache;
70  
71  struct xfs_bmap_intent;
72  
73  void xfs_bmap_defer_add(struct xfs_trans *tp, struct xfs_bmap_intent *bi);
74  
75  #endif	/* __XFS_BMAP_ITEM_H__ */
76