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