LXR linux/fs/xfs/xfs_rmap

   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_RMAP_ITEM_H__
   7#define __XFS_RMAP_ITEM_H__
   8
   9/*
  10 * There are (currently) three pairs of rmap btree redo item types: map, unmap,
  11 * and convert.  The common abbreviations for these are RUI (rmap update
  12 * intent) and RUD (rmap update done).  The redo item type is encoded in the
  13 * 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 transaction
  17 * that records the associated rmapbt updates.  Typically, the first
  18 * transaction will record a bmbt update, followed by some number of
  19 * transactions containing rmapbt updates, and finally transactions with any
  20 * bnobt/cntbt updates.
  21 *
  22 * Should the system crash after the commit of the first transaction but
  23 * before the commit of the final transaction in a series, log recovery will
  24 * use the redo information recorded by the intent items to replay the
  25 * (rmapbt/bnobt/cntbt) metadata updates in the non-first transaction.
  26 */
  27
  28/* kernel only RUI/RUD definitions */
  29
  30struct xfs_mount;
  31struct kmem_cache;
  32
  33/*
  34 * Max number of extents in fast allocation path.
  35 */
  36#define XFS_RUI_MAX_FAST_EXTENTS        16
  37
  38/*
  39 * This is the "rmap update intent" log item.  It is used to log the fact that
  40 * some reverse mappings need to change.  It is used in conjunction with the
  41 * "rmap update done" log item described below.
  42 *
  43 * These log items follow the same rules as struct xfs_efi_log_item; see the
  44 * comments about that structure (in xfs_extfree_item.h) for more details.
  45 */
  46struct xfs_rui_log_item {
  47        struct xfs_log_item             rui_item;
  48        atomic_t                        rui_refcount;
  49        atomic_t                        rui_next_extent;
  50        struct xfs_rui_log_format       rui_format;
  51};
  52
  53static inline size_t
  54xfs_rui_log_item_sizeof(
  55        unsigned int            nr)
  56{
  57        return offsetof(struct xfs_rui_log_item, rui_format) +
  58                        xfs_rui_log_format_sizeof(nr);
  59}
  60
  61/*
  62 * This is the "rmap update done" log item.  It is used to log the fact that
  63 * some rmapbt updates mentioned in an earlier rui item have been performed.
  64 */
  65struct xfs_rud_log_item {
  66        struct xfs_log_item             rud_item;
  67        struct xfs_rui_log_item         *rud_ruip;
  68        struct xfs_rud_log_format       rud_format;
  69};
  70
  71extern struct kmem_cache        *xfs_rui_cache;
  72extern struct kmem_cache        *xfs_rud_cache;
  73
  74#endif  /* __XFS_RMAP_ITEM_H__ */
  75