linux/fs/xfs/xfs_alloc_btree.h
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   1/*
   2 * Copyright (c) 2000,2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#ifndef __XFS_ALLOC_BTREE_H__
  19#define __XFS_ALLOC_BTREE_H__
  20
  21/*
  22 * Freespace on-disk structures
  23 */
  24
  25struct xfs_buf;
  26struct xfs_btree_cur;
  27struct xfs_mount;
  28
  29/*
  30 * There are two on-disk btrees, one sorted by blockno and one sorted
  31 * by blockcount and blockno.  All blocks look the same to make the code
  32 * simpler; if we have time later, we'll make the optimizations.
  33 */
  34#define XFS_ABTB_MAGIC          0x41425442      /* 'ABTB' for bno tree */
  35#define XFS_ABTB_CRC_MAGIC      0x41423342      /* 'AB3B' */
  36#define XFS_ABTC_MAGIC          0x41425443      /* 'ABTC' for cnt tree */
  37#define XFS_ABTC_CRC_MAGIC      0x41423343      /* 'AB3C' */
  38
  39/*
  40 * Data record/key structure
  41 */
  42typedef struct xfs_alloc_rec {
  43        __be32          ar_startblock;  /* starting block number */
  44        __be32          ar_blockcount;  /* count of free blocks */
  45} xfs_alloc_rec_t, xfs_alloc_key_t;
  46
  47typedef struct xfs_alloc_rec_incore {
  48        xfs_agblock_t   ar_startblock;  /* starting block number */
  49        xfs_extlen_t    ar_blockcount;  /* count of free blocks */
  50} xfs_alloc_rec_incore_t;
  51
  52/* btree pointer type */
  53typedef __be32 xfs_alloc_ptr_t;
  54
  55/*
  56 * Block numbers in the AG:
  57 * SB is sector 0, AGF is sector 1, AGI is sector 2, AGFL is sector 3.
  58 */
  59#define XFS_BNO_BLOCK(mp)       ((xfs_agblock_t)(XFS_AGFL_BLOCK(mp) + 1))
  60#define XFS_CNT_BLOCK(mp)       ((xfs_agblock_t)(XFS_BNO_BLOCK(mp) + 1))
  61
  62/*
  63 * Btree block header size depends on a superblock flag.
  64 */
  65#define XFS_ALLOC_BLOCK_LEN(mp) \
  66        (xfs_sb_version_hascrc(&((mp)->m_sb)) ? \
  67                XFS_BTREE_SBLOCK_CRC_LEN : XFS_BTREE_SBLOCK_LEN)
  68
  69/*
  70 * Record, key, and pointer address macros for btree blocks.
  71 *
  72 * (note that some of these may appear unused, but they are used in userspace)
  73 */
  74#define XFS_ALLOC_REC_ADDR(mp, block, index) \
  75        ((xfs_alloc_rec_t *) \
  76                ((char *)(block) + \
  77                 XFS_ALLOC_BLOCK_LEN(mp) + \
  78                 (((index) - 1) * sizeof(xfs_alloc_rec_t))))
  79
  80#define XFS_ALLOC_KEY_ADDR(mp, block, index) \
  81        ((xfs_alloc_key_t *) \
  82                ((char *)(block) + \
  83                 XFS_ALLOC_BLOCK_LEN(mp) + \
  84                 ((index) - 1) * sizeof(xfs_alloc_key_t)))
  85
  86#define XFS_ALLOC_PTR_ADDR(mp, block, index, maxrecs) \
  87        ((xfs_alloc_ptr_t *) \
  88                ((char *)(block) + \
  89                 XFS_ALLOC_BLOCK_LEN(mp) + \
  90                 (maxrecs) * sizeof(xfs_alloc_key_t) + \
  91                 ((index) - 1) * sizeof(xfs_alloc_ptr_t)))
  92
  93extern struct xfs_btree_cur *xfs_allocbt_init_cursor(struct xfs_mount *,
  94                struct xfs_trans *, struct xfs_buf *,
  95                xfs_agnumber_t, xfs_btnum_t);
  96extern int xfs_allocbt_maxrecs(struct xfs_mount *, int, int);
  97
  98extern const struct xfs_buf_ops xfs_allocbt_buf_ops;
  99
 100#endif  /* __XFS_ALLOC_BTREE_H__ */
 101
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