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// SPDX-License-Identifier: GPL-2.0+
* Copyright (C) 2016 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <>
* There are (currently) two pairs of refcount btree redo item types:
* increase and decrease. The log items for these are CUI (refcount
* update intent) and CUD (refcount update done). The redo item type
* is encoded in the flags field of each xfs_map_extent.
* *I items should be recorded in the *first* of a series of rolled
* transactions, and the *D items should be recorded in the same
* transaction that records the associated refcountbt updates.
* Should the system crash after the commit of the first transaction
* but before the commit of the final transaction in a series, log
* recovery will use the redo information recorded by the intent items
* to replay the refcountbt metadata updates.
/* kernel only CUI/CUD definitions */
struct xfs_mount;
struct kmem_zone;
* Max number of extents in fast allocation path.
* This is the "refcount update intent" log item. It is used to log
* the fact that some reverse mappings need to change. It is used in
* conjunction with the "refcount update done" log item described
* below.
* These log items follow the same rules as struct xfs_efi_log_item;
* see the comments about that structure (in xfs_extfree_item.h) for
* more details.
struct xfs_cui_log_item {
struct xfs_log_item cui_item;
atomic_t cui_refcount;
atomic_t cui_next_extent;
struct xfs_cui_log_format cui_format;
static inline size_t
unsigned int nr)
return offsetof(struct xfs_cui_log_item, cui_format) +
* This is the "refcount update done" log item. It is used to log the
* fact that some refcountbt updates mentioned in an earlier cui item
* have been performed.
struct xfs_cud_log_item {
struct xfs_log_item cud_item;
struct xfs_cui_log_item *cud_cuip;
struct xfs_cud_log_format cud_format;
extern struct kmem_zone *xfs_cui_zone;
extern struct kmem_zone *xfs_cud_zone;
#endif /* __XFS_REFCOUNT_ITEM_H__ */