LXR linux/fs/xfs/xfs_refcount

   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_REFCOUNT_ITEM_H__
   7#define __XFS_REFCOUNT_ITEM_H__
   8
   9/*
  10 * There are (currently) two pairs of refcount btree redo item types:
  11 * increase and decrease.  The log items for these are CUI (refcount
  12 * update intent) and CUD (refcount update done).  The redo item type
  13 * is encoded in the 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
  17 * transaction that records the associated refcountbt updates.
  18 *
  19 * Should the system crash after the commit of the first transaction
  20 * but before the commit of the final transaction in a series, log
  21 * recovery will use the redo information recorded by the intent items
  22 * to replay the refcountbt metadata updates.
  23 */
  24
  25/* kernel only CUI/CUD definitions */
  26
  27struct xfs_mount;
  28struct kmem_zone;
  29
  30/*
  31 * Max number of extents in fast allocation path.
  32 */
  33#define XFS_CUI_MAX_FAST_EXTENTS        16
  34
  35/*
  36 * This is the "refcount update intent" log item.  It is used to log
  37 * the fact that some reverse mappings need to change.  It is used in
  38 * conjunction with the "refcount update done" log item described
  39 * below.
  40 *
  41 * These log items follow the same rules as struct xfs_efi_log_item;
  42 * see the comments about that structure (in xfs_extfree_item.h) for
  43 * more details.
  44 */
  45struct xfs_cui_log_item {
  46        struct xfs_log_item             cui_item;
  47        atomic_t                        cui_refcount;
  48        atomic_t                        cui_next_extent;
  49        struct xfs_cui_log_format       cui_format;
  50};
  51
  52static inline size_t
  53xfs_cui_log_item_sizeof(
  54        unsigned int            nr)
  55{
  56        return offsetof(struct xfs_cui_log_item, cui_format) +
  57                        xfs_cui_log_format_sizeof(nr);
  58}
  59
  60/*
  61 * This is the "refcount update done" log item.  It is used to log the
  62 * fact that some refcountbt updates mentioned in an earlier cui item
  63 * have been performed.
  64 */
  65struct xfs_cud_log_item {
  66        struct xfs_log_item             cud_item;
  67        struct xfs_cui_log_item         *cud_cuip;
  68        struct xfs_cud_log_format       cud_format;
  69};
  70
  71extern struct kmem_zone *xfs_cui_zone;
  72extern struct kmem_zone *xfs_cud_zone;
  73
  74#endif  /* __XFS_REFCOUNT_ITEM_H__ */
  75