LXR linux/fs/xfs/xfs_alloc

   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_ABTC_MAGIC  0x41425443      /* 'ABTC' for cnt tree */
  36
  37/*
  38 * Data record/key structure
  39 */
  40typedef struct xfs_alloc_rec {
  41        __be32          ar_startblock;  /* starting block number */
  42        __be32          ar_blockcount;  /* count of free blocks */
  43} xfs_alloc_rec_t, xfs_alloc_key_t;
  44
  45typedef struct xfs_alloc_rec_incore {
  46        xfs_agblock_t   ar_startblock;  /* starting block number */
  47        xfs_extlen_t    ar_blockcount;  /* count of free blocks */
  48} xfs_alloc_rec_incore_t;
  49
  50/* btree pointer type */
  51typedef __be32 xfs_alloc_ptr_t;
  52
  53/*
  54 * Minimum and maximum blocksize and sectorsize.
  55 * The blocksize upper limit is pretty much arbitrary.
  56 * The sectorsize upper limit is due to sizeof(sb_sectsize).
  57 */
  58#define XFS_MIN_BLOCKSIZE_LOG   9       /* i.e. 512 bytes */
  59#define XFS_MAX_BLOCKSIZE_LOG   16      /* i.e. 65536 bytes */
  60#define XFS_MIN_BLOCKSIZE       (1 << XFS_MIN_BLOCKSIZE_LOG)
  61#define XFS_MAX_BLOCKSIZE       (1 << XFS_MAX_BLOCKSIZE_LOG)
  62#define XFS_MIN_SECTORSIZE_LOG  9       /* i.e. 512 bytes */
  63#define XFS_MAX_SECTORSIZE_LOG  15      /* i.e. 32768 bytes */
  64#define XFS_MIN_SECTORSIZE      (1 << XFS_MIN_SECTORSIZE_LOG)
  65#define XFS_MAX_SECTORSIZE      (1 << XFS_MAX_SECTORSIZE_LOG)
  66
  67/*
  68 * Block numbers in the AG:
  69 * SB is sector 0, AGF is sector 1, AGI is sector 2, AGFL is sector 3.
  70 */
  71#define XFS_BNO_BLOCK(mp)       ((xfs_agblock_t)(XFS_AGFL_BLOCK(mp) + 1))
  72#define XFS_CNT_BLOCK(mp)       ((xfs_agblock_t)(XFS_BNO_BLOCK(mp) + 1))
  73
  74/*
  75 * Btree block header size depends on a superblock flag.
  76 *
  77 * (not quite yet, but soon)
  78 */
  79#define XFS_ALLOC_BLOCK_LEN(mp) XFS_BTREE_SBLOCK_LEN
  80
  81/*
  82 * Record, key, and pointer address macros for btree blocks.
  83 *
  84 * (note that some of these may appear unused, but they are used in userspace)
  85 */
  86#define XFS_ALLOC_REC_ADDR(mp, block, index) \
  87        ((xfs_alloc_rec_t *) \
  88                ((char *)(block) + \
  89                 XFS_ALLOC_BLOCK_LEN(mp) + \
  90                 (((index) - 1) * sizeof(xfs_alloc_rec_t))))
  91
  92#define XFS_ALLOC_KEY_ADDR(mp, block, index) \
  93        ((xfs_alloc_key_t *) \
  94                ((char *)(block) + \
  95                 XFS_ALLOC_BLOCK_LEN(mp) + \
  96                 ((index) - 1) * sizeof(xfs_alloc_key_t)))
  97
  98#define XFS_ALLOC_PTR_ADDR(mp, block, index, maxrecs) \
  99        ((xfs_alloc_ptr_t *) \
 100                ((char *)(block) + \
 101                 XFS_ALLOC_BLOCK_LEN(mp) + \
 102                 (maxrecs) * sizeof(xfs_alloc_key_t) + \
 103                 ((index) - 1) * sizeof(xfs_alloc_ptr_t)))
 104
 105extern struct xfs_btree_cur *xfs_allocbt_init_cursor(struct xfs_mount *,
 106                struct xfs_trans *, struct xfs_buf *,
 107                xfs_agnumber_t, xfs_btnum_t);
 108extern int xfs_allocbt_maxrecs(struct xfs_mount *, int, int);
 109
 110#endif  /* __XFS_ALLOC_BTREE_H__ */
 111