fs/xfs/xfs_alloc_btree.h

   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
  25 struct xfs_buf;
  26 struct xfs_btree_cur;
  27 struct 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  */
  42 typedef 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
  47 typedef 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 */
  53 typedef __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
  93 extern 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);
  96 extern int xfs_allocbt_maxrecs(struct xfs_mount *, int, int);
  97
  98 extern const struct xfs_buf_ops xfs_allocbt_buf_ops;
  99
 100 #endif  /* __XFS_ALLOC_BTREE_H__ */