fs/xfs/xfs_dir2_data.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_DIR2_DATA_H__
  19 #define __XFS_DIR2_DATA_H__
  20
  21 /*
  22  * Directory format 2, data block structures.
  23  */
  24
  25 struct xfs_dabuf;
  26 struct xfs_da_args;
  27 struct xfs_inode;
  28 struct 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  */
  67 typedef 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  */
  77 typedef 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  */
  87 typedef 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  */
  99 typedef 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
 106 typedef 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  */
 114 typedef 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  */
 126 static 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  */
 135 static inline __be16 *
 136 xfs_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  */
 145 static inline __be16 *
 146 xfs_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
 156 extern 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
 160 extern xfs_dir2_data_free_t *xfs_dir2_data_freefind(xfs_dir2_data_t *d,
 161                                 xfs_dir2_data_unused_t *dup);
 162 extern xfs_dir2_data_free_t *xfs_dir2_data_freeinsert(xfs_dir2_data_t *d,
 163                                 xfs_dir2_data_unused_t *dup, int *loghead);
 164 extern void xfs_dir2_data_freescan(struct xfs_mount *mp, xfs_dir2_data_t *d,
 165                                 int *loghead);
 166 extern int xfs_dir2_data_init(struct xfs_da_args *args, xfs_dir2_db_t blkno,
 167                                 struct xfs_dabuf **bpp);
 168 extern void xfs_dir2_data_log_entry(struct xfs_trans *tp, struct xfs_dabuf *bp,
 169                                 xfs_dir2_data_entry_t *dep);
 170 extern void xfs_dir2_data_log_header(struct xfs_trans *tp,
 171                                 struct xfs_dabuf *bp);
 172 extern void xfs_dir2_data_log_unused(struct xfs_trans *tp, struct xfs_dabuf *bp,
 173                                 xfs_dir2_data_unused_t *dup);
 174 extern 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);
 178 extern 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__ */