LXR linux/fs/xfs/xfs_dir2

   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_DIR2_DATA_H__
  19#define __XFS_DIR2_DATA_H__
  20
  21/*
  22 * Directory format 2, data block structures.
  23 */
  24
  25struct xfs_dabuf;
  26struct xfs_da_args;
  27struct xfs_inode;
  28struct xfs_trans;
  29
  30/*
  31 * Constants.
  32 */
  33#define XFS_DIR2_DATA_MAGIC     0x58443244      /* XD2D: for multiblock dirs */
  34#define XFS_DIR2_DATA_ALIGN_LOG 3               /* i.e., 8 bytes */
  35#define XFS_DIR2_DATA_ALIGN     (1 << XFS_DIR2_DATA_ALIGN_LOG)
  36#define XFS_DIR2_DATA_FREE_TAG  0xffff
  37#define XFS_DIR2_DATA_FD_COUNT  3
  38
  39/*
  40 * Directory address space divided into sections,
  41 * spaces separated by 32GB.
  42 */
  43#define XFS_DIR2_SPACE_SIZE     (1ULL << (32 + XFS_DIR2_DATA_ALIGN_LOG))
  44#define XFS_DIR2_DATA_SPACE     0
  45#define XFS_DIR2_DATA_OFFSET    (XFS_DIR2_DATA_SPACE * XFS_DIR2_SPACE_SIZE)
  46#define XFS_DIR2_DATA_FIRSTDB(mp)       \
  47        xfs_dir2_byte_to_db(mp, XFS_DIR2_DATA_OFFSET)
  48
  49/*
  50 * Offsets of . and .. in data space (always block 0)
  51 */
  52#define XFS_DIR2_DATA_DOT_OFFSET        \
  53        ((xfs_dir2_data_aoff_t)sizeof(xfs_dir2_data_hdr_t))
  54#define XFS_DIR2_DATA_DOTDOT_OFFSET     \
  55        (XFS_DIR2_DATA_DOT_OFFSET + xfs_dir2_data_entsize(1))
  56#define XFS_DIR2_DATA_FIRST_OFFSET              \
  57        (XFS_DIR2_DATA_DOTDOT_OFFSET + xfs_dir2_data_entsize(2))
  58
  59/*
  60 * Structures.
  61 */
  62
  63/*
  64 * Describe a free area in the data block.
  65 * The freespace will be formatted as a xfs_dir2_data_unused_t.
  66 */
  67typedef struct xfs_dir2_data_free {
  68        __be16                  offset;         /* start of freespace */
  69        __be16                  length;         /* length of freespace */
  70} xfs_dir2_data_free_t;
  71
  72/*
  73 * Header for the data blocks.
  74 * Always at the beginning of a directory-sized block.
  75 * The code knows that XFS_DIR2_DATA_FD_COUNT is 3.
  76 */
  77typedef struct xfs_dir2_data_hdr {
  78        __be32                  magic;          /* XFS_DIR2_DATA_MAGIC */
  79                                                /* or XFS_DIR2_BLOCK_MAGIC */
  80        xfs_dir2_data_free_t    bestfree[XFS_DIR2_DATA_FD_COUNT];
  81} xfs_dir2_data_hdr_t;
  82
  83/*
  84 * Active entry in a data block.  Aligned to 8 bytes.
  85 * Tag appears as the last 2 bytes.
  86 */
  87typedef struct xfs_dir2_data_entry {
  88        __be64                  inumber;        /* inode number */
  89        __u8                    namelen;        /* name length */
  90        __u8                    name[1];        /* name bytes, no null */
  91                                                /* variable offset */
  92        __be16                  tag;            /* starting offset of us */
  93} xfs_dir2_data_entry_t;
  94
  95/*
  96 * Unused entry in a data block.  Aligned to 8 bytes.
  97 * Tag appears as the last 2 bytes.
  98 */
  99typedef struct xfs_dir2_data_unused {
 100        __be16                  freetag;        /* XFS_DIR2_DATA_FREE_TAG */
 101        __be16                  length;         /* total free length */
 102                                                /* variable offset */
 103        __be16                  tag;            /* starting offset of us */
 104} xfs_dir2_data_unused_t;
 105
 106typedef union {
 107        xfs_dir2_data_entry_t   entry;
 108        xfs_dir2_data_unused_t  unused;
 109} xfs_dir2_data_union_t;
 110
 111/*
 112 * Generic data block structure, for xfs_db.
 113 */
 114typedef struct xfs_dir2_data {
 115        xfs_dir2_data_hdr_t     hdr;            /* magic XFS_DIR2_DATA_MAGIC */
 116        xfs_dir2_data_union_t   u[1];
 117} xfs_dir2_data_t;
 118
 119/*
 120 * Macros.
 121 */
 122
 123/*
 124 * Size of a data entry.
 125 */
 126static inline int xfs_dir2_data_entsize(int n)
 127{
 128        return (int)roundup(offsetof(xfs_dir2_data_entry_t, name[0]) + (n) + \
 129                 (uint)sizeof(xfs_dir2_data_off_t), XFS_DIR2_DATA_ALIGN);
 130}
 131
 132/*
 133 * Pointer to an entry's tag word.
 134 */
 135static inline __be16 *
 136xfs_dir2_data_entry_tag_p(xfs_dir2_data_entry_t *dep)
 137{
 138        return (__be16 *)((char *)dep +
 139                xfs_dir2_data_entsize(dep->namelen) - sizeof(__be16));
 140}
 141
 142/*
 143 * Pointer to a freespace's tag word.
 144 */
 145static inline __be16 *
 146xfs_dir2_data_unused_tag_p(xfs_dir2_data_unused_t *dup)
 147{
 148        return (__be16 *)((char *)dup +
 149                        be16_to_cpu(dup->length) - sizeof(__be16));
 150}
 151
 152/*
 153 * Function declarations.
 154 */
 155#ifdef DEBUG
 156extern void xfs_dir2_data_check(struct xfs_inode *dp, struct xfs_dabuf *bp);
 157#else
 158#define xfs_dir2_data_check(dp,bp)
 159#endif
 160extern xfs_dir2_data_free_t *xfs_dir2_data_freefind(xfs_dir2_data_t *d,
 161                                xfs_dir2_data_unused_t *dup);
 162extern xfs_dir2_data_free_t *xfs_dir2_data_freeinsert(xfs_dir2_data_t *d,
 163                                xfs_dir2_data_unused_t *dup, int *loghead);
 164extern void xfs_dir2_data_freescan(struct xfs_mount *mp, xfs_dir2_data_t *d,
 165                                int *loghead);
 166extern int xfs_dir2_data_init(struct xfs_da_args *args, xfs_dir2_db_t blkno,
 167                                struct xfs_dabuf **bpp);
 168extern void xfs_dir2_data_log_entry(struct xfs_trans *tp, struct xfs_dabuf *bp,
 169                                xfs_dir2_data_entry_t *dep);
 170extern void xfs_dir2_data_log_header(struct xfs_trans *tp,
 171                                struct xfs_dabuf *bp);
 172extern void xfs_dir2_data_log_unused(struct xfs_trans *tp, struct xfs_dabuf *bp,
 173                                xfs_dir2_data_unused_t *dup);
 174extern void xfs_dir2_data_make_free(struct xfs_trans *tp, struct xfs_dabuf *bp,
 175                                xfs_dir2_data_aoff_t offset,
 176                                xfs_dir2_data_aoff_t len, int *needlogp,
 177                                int *needscanp);
 178extern void xfs_dir2_data_use_free(struct xfs_trans *tp, struct xfs_dabuf *bp,
 179                               xfs_dir2_data_unused_t *dup,
 180                               xfs_dir2_data_aoff_t offset,
 181                               xfs_dir2_data_aoff_t len, int *needlogp,
 182                               int *needscanp);
 183
 184#endif  /* __XFS_DIR2_DATA_H__ */
 185