LXR linux/fs/xfs/xfs_bmap

   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
  27struct xfs_mount;
  28struct kmem_zone;
  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 */
  43struct 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
  50static inline size_t
  51xfs_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 */
  62struct 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
  68extern struct kmem_zone *xfs_bui_zone;
  69extern struct kmem_zone *xfs_bud_zone;
  70
  71#endif  /* __XFS_BMAP_ITEM_H__ */
  72