fs/xfs/xfs_bmap_item.h

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Copyright (C) 2016 Oracle.  All Rights Reserved.
0004  * Author: Darrick J. Wong <darrick.wong@oracle.com>
0005  */
0006 #ifndef __XFS_BMAP_ITEM_H__
0007 #define __XFS_BMAP_ITEM_H__
0008
0009 /*
0010  * There are (currently) two pairs of bmap btree redo item types: map & unmap.
0011  * The common abbreviations for these are BUI (bmap update intent) and BUD
0012  * (bmap update done).  The redo item type is encoded in the flags field of
0013  * each xfs_map_extent.
0014  *
0015  * *I items should be recorded in the *first* of a series of rolled
0016  * transactions, and the *D items should be recorded in the same transaction
0017  * that records the associated bmbt updates.
0018  *
0019  * Should the system crash after the commit of the first transaction but
0020  * before the commit of the final transaction in a series, log recovery will
0021  * use the redo information recorded by the intent items to replay the
0022  * bmbt metadata updates in the non-first transaction.
0023  */
0024
0025 /* kernel only BUI/BUD definitions */
0026
0027 struct xfs_mount;
0028 struct kmem_cache;
0029
0030 /*
0031  * Max number of extents in fast allocation path.
0032  */
0033 #define XFS_BUI_MAX_FAST_EXTENTS    1
0034
0035 /*
0036  * This is the "bmap update intent" log item.  It is used to log the fact that
0037  * some reverse mappings need to change.  It is used in conjunction with the
0038  * "bmap update done" log item described below.
0039  *
0040  * These log items follow the same rules as struct xfs_efi_log_item; see the
0041  * comments about that structure (in xfs_extfree_item.h) for more details.
0042  */
0043 struct xfs_bui_log_item {
0044     struct xfs_log_item     bui_item;
0045     atomic_t            bui_refcount;
0046     atomic_t            bui_next_extent;
0047     struct xfs_bui_log_format   bui_format;
0048 };
0049
0050 static inline size_t
0051 xfs_bui_log_item_sizeof(
0052     unsigned int        nr)
0053 {
0054     return offsetof(struct xfs_bui_log_item, bui_format) +
0055             xfs_bui_log_format_sizeof(nr);
0056 }
0057
0058 /*
0059  * This is the "bmap update done" log item.  It is used to log the fact that
0060  * some bmbt updates mentioned in an earlier bui item have been performed.
0061  */
0062 struct xfs_bud_log_item {
0063     struct xfs_log_item     bud_item;
0064     struct xfs_bui_log_item     *bud_buip;
0065     struct xfs_bud_log_format   bud_format;
0066 };
0067
0068 extern struct kmem_cache    *xfs_bui_cache;
0069 extern struct kmem_cache    *xfs_bud_cache;
0070
0071 #endif  /* __XFS_BMAP_ITEM_H__ */