fs/xfs/xfs_refcount_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_REFCOUNT_ITEM_H__
0007 #define __XFS_REFCOUNT_ITEM_H__
0008
0009 /*
0010  * There are (currently) two pairs of refcount btree redo item types:
0011  * increase and decrease.  The log items for these are CUI (refcount
0012  * update intent) and CUD (refcount update done).  The redo item type
0013  * is encoded in the flags field of 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
0017  * transaction that records the associated refcountbt updates.
0018  *
0019  * Should the system crash after the commit of the first transaction
0020  * but before the commit of the final transaction in a series, log
0021  * recovery will use the redo information recorded by the intent items
0022  * to replay the refcountbt metadata updates.
0023  */
0024
0025 /* kernel only CUI/CUD 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_CUI_MAX_FAST_EXTENTS    16
0034
0035 /*
0036  * This is the "refcount update intent" log item.  It is used to log
0037  * the fact that some reverse mappings need to change.  It is used in
0038  * conjunction with the "refcount update done" log item described
0039  * below.
0040  *
0041  * These log items follow the same rules as struct xfs_efi_log_item;
0042  * see the comments about that structure (in xfs_extfree_item.h) for
0043  * more details.
0044  */
0045 struct xfs_cui_log_item {
0046     struct xfs_log_item     cui_item;
0047     atomic_t            cui_refcount;
0048     atomic_t            cui_next_extent;
0049     struct xfs_cui_log_format   cui_format;
0050 };
0051
0052 static inline size_t
0053 xfs_cui_log_item_sizeof(
0054     unsigned int        nr)
0055 {
0056     return offsetof(struct xfs_cui_log_item, cui_format) +
0057             xfs_cui_log_format_sizeof(nr);
0058 }
0059
0060 /*
0061  * This is the "refcount update done" log item.  It is used to log the
0062  * fact that some refcountbt updates mentioned in an earlier cui item
0063  * have been performed.
0064  */
0065 struct xfs_cud_log_item {
0066     struct xfs_log_item     cud_item;
0067     struct xfs_cui_log_item     *cud_cuip;
0068     struct xfs_cud_log_format   cud_format;
0069 };
0070
0071 extern struct kmem_cache    *xfs_cui_cache;
0072 extern struct kmem_cache    *xfs_cud_cache;
0073
0074 #endif  /* __XFS_REFCOUNT_ITEM_H__ */