fs/xfs/xfs_rmap_item.h

   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
  30 struct xfs_mount;
  31 struct kmem_zone;
  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  */
  46 struct 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
  53 static inline size_t
  54 xfs_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  */
  65 struct 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
  71 extern struct kmem_zone *xfs_rui_zone;
  72 extern struct kmem_zone *xfs_rud_zone;
  73
  74 #endif  /* __XFS_RMAP_ITEM_H__ */