xref: /openbmc/linux/fs/xfs/xfs_bmap_item.h (revision 182696fb)
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 #endif	/* __XFS_BMAP_ITEM_H__ */
72