fs/xfs/xfs_dir2_format.h

   1 /*
   2  * Copyright (c) 2000-2001,2005 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_FORMAT_H__
  19 #define __XFS_DIR2_FORMAT_H__
  20
  21 /*
  22  * Directory version 2.
  23  *
  24  * There are 4 possible formats:
  25  *  - shortform - embedded into the inode
  26  *  - single block - data with embedded leaf at the end
  27  *  - multiple data blocks, single leaf+freeindex block
  28  *  - data blocks, node and leaf blocks (btree), freeindex blocks
  29  *
  30  * Note: many node blocks structures and constants are shared with the attr
  31  * code and defined in xfs_da_btree.h.
  32  */
  33
  34 #define XFS_DIR2_BLOCK_MAGIC    0x58443242      /* XD2B: single block dirs */
  35 #define XFS_DIR2_DATA_MAGIC     0x58443244      /* XD2D: multiblock dirs */
  36 #define XFS_DIR2_FREE_MAGIC     0x58443246      /* XD2F: free index blocks */
  37
  38 /*
  39  * Byte offset in data block and shortform entry.
  40  */
  41 typedef __uint16_t      xfs_dir2_data_off_t;
  42 #define NULLDATAOFF     0xffffU
  43 typedef uint            xfs_dir2_data_aoff_t;   /* argument form */
  44
  45 /*
  46  * Normalized offset (in a data block) of the entry, really xfs_dir2_data_off_t.
  47  * Only need 16 bits, this is the byte offset into the single block form.
  48  */
  49 typedef struct { __uint8_t i[2]; } __arch_pack xfs_dir2_sf_off_t;
  50
  51 /*
  52  * Offset in data space of a data entry.
  53  */
  54 typedef __uint32_t      xfs_dir2_dataptr_t;
  55 #define XFS_DIR2_MAX_DATAPTR    ((xfs_dir2_dataptr_t)0xffffffff)
  56 #define XFS_DIR2_NULL_DATAPTR   ((xfs_dir2_dataptr_t)0)
  57
  58 /*
  59  * Byte offset in a directory.
  60  */
  61 typedef xfs_off_t       xfs_dir2_off_t;
  62
  63 /*
  64  * Directory block number (logical dirblk in file)
  65  */
  66 typedef __uint32_t      xfs_dir2_db_t;
  67
  68 /*
  69  * Inode number stored as 8 8-bit values.
  70  */
  71 typedef struct { __uint8_t i[8]; } xfs_dir2_ino8_t;
  72
  73 /*
  74  * Inode number stored as 4 8-bit values.
  75  * Works a lot of the time, when all the inode numbers in a directory
  76  * fit in 32 bits.
  77  */
  78 typedef struct { __uint8_t i[4]; } xfs_dir2_ino4_t;
  79
  80 typedef union {
  81         xfs_dir2_ino8_t i8;
  82         xfs_dir2_ino4_t i4;
  83 } xfs_dir2_inou_t;
  84 #define XFS_DIR2_MAX_SHORT_INUM ((xfs_ino_t)0xffffffffULL)
  85
  86 /*
  87  * Directory layout when stored internal to an inode.
  88  *
  89  * Small directories are packed as tightly as possible so as to fit into the
  90  * literal area of the inode.  These "shortform" directories consist of a
  91  * single xfs_dir2_sf_hdr header followed by zero or more xfs_dir2_sf_entry
  92  * structures.  Due the different inode number storage size and the variable
  93  * length name field in the xfs_dir2_sf_entry all these structure are
  94  * variable length, and the accessors in this file should be used to iterate
  95  * over them.
  96  */
  97 typedef struct xfs_dir2_sf_hdr {
  98         __uint8_t               count;          /* count of entries */
  99         __uint8_t               i8count;        /* count of 8-byte inode #s */
 100         xfs_dir2_inou_t         parent;         /* parent dir inode number */
 101 } __arch_pack xfs_dir2_sf_hdr_t;
 102
 103 typedef struct xfs_dir2_sf_entry {
 104         __u8                    namelen;        /* actual name length */
 105         xfs_dir2_sf_off_t       offset;         /* saved offset */
 106         __u8                    name[];         /* name, variable size */
 107         /*
 108          * A xfs_dir2_ino8_t or xfs_dir2_ino4_t follows here, at a
 109          * variable offset after the name.
 110          */
 111 } __arch_pack xfs_dir2_sf_entry_t;
 112
 113 static inline int xfs_dir2_sf_hdr_size(int i8count)
 114 {
 115         return sizeof(struct xfs_dir2_sf_hdr) -
 116                 (i8count == 0) *
 117                 (sizeof(xfs_dir2_ino8_t) - sizeof(xfs_dir2_ino4_t));
 118 }
 119
 120 static inline xfs_dir2_data_aoff_t
 121 xfs_dir2_sf_get_offset(xfs_dir2_sf_entry_t *sfep)
 122 {
 123         return get_unaligned_be16(&sfep->offset.i);
 124 }
 125
 126 static inline void
 127 xfs_dir2_sf_put_offset(xfs_dir2_sf_entry_t *sfep, xfs_dir2_data_aoff_t off)
 128 {
 129         put_unaligned_be16(off, &sfep->offset.i);
 130 }
 131
 132 static inline int
 133 xfs_dir2_sf_entsize(struct xfs_dir2_sf_hdr *hdr, int len)
 134 {
 135         return sizeof(struct xfs_dir2_sf_entry) +       /* namelen + offset */
 136                 len +                                   /* name */
 137                 (hdr->i8count ?                         /* ino */
 138                  sizeof(xfs_dir2_ino8_t) :
 139                  sizeof(xfs_dir2_ino4_t));
 140 }
 141
 142 static inline struct xfs_dir2_sf_entry *
 143 xfs_dir2_sf_firstentry(struct xfs_dir2_sf_hdr *hdr)
 144 {
 145         return (struct xfs_dir2_sf_entry *)
 146                 ((char *)hdr + xfs_dir2_sf_hdr_size(hdr->i8count));
 147 }
 148
 149 static inline struct xfs_dir2_sf_entry *
 150 xfs_dir2_sf_nextentry(struct xfs_dir2_sf_hdr *hdr,
 151                 struct xfs_dir2_sf_entry *sfep)
 152 {
 153         return (struct xfs_dir2_sf_entry *)
 154                 ((char *)sfep + xfs_dir2_sf_entsize(hdr, sfep->namelen));
 155 }
 156
 157
 158 /*
 159  * Data block structures.
 160  *
 161  * A pure data block looks like the following drawing on disk:
 162  *
 163  *    +-------------------------------------------------+
 164  *    | xfs_dir2_data_hdr_t                             |
 165  *    +-------------------------------------------------+
 166  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
 167  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
 168  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
 169  *    | ...                                             |
 170  *    +-------------------------------------------------+
 171  *    | unused space                                    |
 172  *    +-------------------------------------------------+
 173  *
 174  * As all the entries are variable size structures the accessors below should
 175  * be used to iterate over them.
 176  *
 177  * In addition to the pure data blocks for the data and node formats,
 178  * most structures are also used for the combined data/freespace "block"
 179  * format below.
 180  */
 181
 182 #define XFS_DIR2_DATA_ALIGN_LOG 3               /* i.e., 8 bytes */
 183 #define XFS_DIR2_DATA_ALIGN     (1 << XFS_DIR2_DATA_ALIGN_LOG)
 184 #define XFS_DIR2_DATA_FREE_TAG  0xffff
 185 #define XFS_DIR2_DATA_FD_COUNT  3
 186
 187 /*
 188  * Directory address space divided into sections,
 189  * spaces separated by 32GB.
 190  */
 191 #define XFS_DIR2_SPACE_SIZE     (1ULL << (32 + XFS_DIR2_DATA_ALIGN_LOG))
 192 #define XFS_DIR2_DATA_SPACE     0
 193 #define XFS_DIR2_DATA_OFFSET    (XFS_DIR2_DATA_SPACE * XFS_DIR2_SPACE_SIZE)
 194 #define XFS_DIR2_DATA_FIRSTDB(mp)       \
 195         xfs_dir2_byte_to_db(mp, XFS_DIR2_DATA_OFFSET)
 196
 197 /*
 198  * Offsets of . and .. in data space (always block 0)
 199  */
 200 #define XFS_DIR2_DATA_DOT_OFFSET        \
 201         ((xfs_dir2_data_aoff_t)sizeof(struct xfs_dir2_data_hdr))
 202 #define XFS_DIR2_DATA_DOTDOT_OFFSET     \
 203         (XFS_DIR2_DATA_DOT_OFFSET + xfs_dir2_data_entsize(1))
 204 #define XFS_DIR2_DATA_FIRST_OFFSET              \
 205         (XFS_DIR2_DATA_DOTDOT_OFFSET + xfs_dir2_data_entsize(2))
 206
 207 /*
 208  * Describe a free area in the data block.
 209  *
 210  * The freespace will be formatted as a xfs_dir2_data_unused_t.
 211  */
 212 typedef struct xfs_dir2_data_free {
 213         __be16                  offset;         /* start of freespace */
 214         __be16                  length;         /* length of freespace */
 215 } xfs_dir2_data_free_t;
 216
 217 /*
 218  * Header for the data blocks.
 219  *
 220  * The code knows that XFS_DIR2_DATA_FD_COUNT is 3.
 221  */
 222 typedef struct xfs_dir2_data_hdr {
 223         __be32                  magic;          /* XFS_DIR2_DATA_MAGIC or */
 224                                                 /* XFS_DIR2_BLOCK_MAGIC */
 225         xfs_dir2_data_free_t    bestfree[XFS_DIR2_DATA_FD_COUNT];
 226 } xfs_dir2_data_hdr_t;
 227
 228 /*
 229  * Active entry in a data block.
 230  *
 231  * Aligned to 8 bytes.  After the variable length name field there is a
 232  * 2 byte tag field, which can be accessed using xfs_dir2_data_entry_tag_p.
 233  */
 234 typedef struct xfs_dir2_data_entry {
 235         __be64                  inumber;        /* inode number */
 236         __u8                    namelen;        /* name length */
 237         __u8                    name[];         /* name bytes, no null */
 238      /* __be16                  tag; */         /* starting offset of us */
 239 } xfs_dir2_data_entry_t;
 240
 241 /*
 242  * Unused entry in a data block.
 243  *
 244  * Aligned to 8 bytes.  Tag appears as the last 2 bytes and must be accessed
 245  * using xfs_dir2_data_unused_tag_p.
 246  */
 247 typedef struct xfs_dir2_data_unused {
 248         __be16                  freetag;        /* XFS_DIR2_DATA_FREE_TAG */
 249         __be16                  length;         /* total free length */
 250                                                 /* variable offset */
 251         __be16                  tag;            /* starting offset of us */
 252 } xfs_dir2_data_unused_t;
 253
 254 /*
 255  * Size of a data entry.
 256  */
 257 static inline int xfs_dir2_data_entsize(int n)
 258 {
 259         return (int)roundup(offsetof(struct xfs_dir2_data_entry, name[0]) + n +
 260                  (uint)sizeof(xfs_dir2_data_off_t), XFS_DIR2_DATA_ALIGN);
 261 }
 262
 263 /*
 264  * Pointer to an entry's tag word.
 265  */
 266 static inline __be16 *
 267 xfs_dir2_data_entry_tag_p(struct xfs_dir2_data_entry *dep)
 268 {
 269         return (__be16 *)((char *)dep +
 270                 xfs_dir2_data_entsize(dep->namelen) - sizeof(__be16));
 271 }
 272
 273 /*
 274  * Pointer to a freespace's tag word.
 275  */
 276 static inline __be16 *
 277 xfs_dir2_data_unused_tag_p(struct xfs_dir2_data_unused *dup)
 278 {
 279         return (__be16 *)((char *)dup +
 280                         be16_to_cpu(dup->length) - sizeof(__be16));
 281 }
 282
 283 /*
 284  * Leaf block structures.
 285  *
 286  * A pure leaf block looks like the following drawing on disk:
 287  *
 288  *    +---------------------------+
 289  *    | xfs_dir2_leaf_hdr_t       |
 290  *    +---------------------------+
 291  *    | xfs_dir2_leaf_entry_t     |
 292  *    | xfs_dir2_leaf_entry_t     |
 293  *    | xfs_dir2_leaf_entry_t     |
 294  *    | xfs_dir2_leaf_entry_t     |
 295  *    | ...                       |
 296  *    +---------------------------+
 297  *    | xfs_dir2_data_off_t       |
 298  *    | xfs_dir2_data_off_t       |
 299  *    | xfs_dir2_data_off_t       |
 300  *    | ...                       |
 301  *    +---------------------------+
 302  *    | xfs_dir2_leaf_tail_t      |
 303  *    +---------------------------+
 304  *
 305  * The xfs_dir2_data_off_t members (bests) and tail are at the end of the block
 306  * for single-leaf (magic = XFS_DIR2_LEAF1_MAGIC) blocks only, but not present
 307  * for directories with separate leaf nodes and free space blocks
 308  * (magic = XFS_DIR2_LEAFN_MAGIC).
 309  *
 310  * As all the entries are variable size structures the accessors below should
 311  * be used to iterate over them.
 312  */
 313
 314 /*
 315  * Offset of the leaf/node space.  First block in this space
 316  * is the btree root.
 317  */
 318 #define XFS_DIR2_LEAF_SPACE     1
 319 #define XFS_DIR2_LEAF_OFFSET    (XFS_DIR2_LEAF_SPACE * XFS_DIR2_SPACE_SIZE)
 320 #define XFS_DIR2_LEAF_FIRSTDB(mp)       \
 321         xfs_dir2_byte_to_db(mp, XFS_DIR2_LEAF_OFFSET)
 322
 323 /*
 324  * Leaf block header.
 325  */
 326 typedef struct xfs_dir2_leaf_hdr {
 327         xfs_da_blkinfo_t        info;           /* header for da routines */
 328         __be16                  count;          /* count of entries */
 329         __be16                  stale;          /* count of stale entries */
 330 } xfs_dir2_leaf_hdr_t;
 331
 332 /*
 333  * Leaf block entry.
 334  */
 335 typedef struct xfs_dir2_leaf_entry {
 336         __be32                  hashval;        /* hash value of name */
 337         __be32                  address;        /* address of data entry */
 338 } xfs_dir2_leaf_entry_t;
 339
 340 /*
 341  * Leaf block tail.
 342  */
 343 typedef struct xfs_dir2_leaf_tail {
 344         __be32                  bestcount;
 345 } xfs_dir2_leaf_tail_t;
 346
 347 /*
 348  * Leaf block.
 349  */
 350 typedef struct xfs_dir2_leaf {
 351         xfs_dir2_leaf_hdr_t     hdr;            /* leaf header */
 352         xfs_dir2_leaf_entry_t   ents[];         /* entries */
 353 } xfs_dir2_leaf_t;
 354
 355 /*
 356  * DB blocks here are logical directory block numbers, not filesystem blocks.
 357  */
 358
 359 static inline int xfs_dir2_max_leaf_ents(struct xfs_mount *mp)
 360 {
 361         return (mp->m_dirblksize - (uint)sizeof(struct xfs_dir2_leaf_hdr)) /
 362                 (uint)sizeof(struct xfs_dir2_leaf_entry);
 363 }
 364
 365 /*
 366  * Get address of the bestcount field in the single-leaf block.
 367  */
 368 static inline struct xfs_dir2_leaf_tail *
 369 xfs_dir2_leaf_tail_p(struct xfs_mount *mp, struct xfs_dir2_leaf *lp)
 370 {
 371         return (struct xfs_dir2_leaf_tail *)
 372                 ((char *)lp + mp->m_dirblksize -
 373                   sizeof(struct xfs_dir2_leaf_tail));
 374 }
 375
 376 /*
 377  * Get address of the bests array in the single-leaf block.
 378  */
 379 static inline __be16 *
 380 xfs_dir2_leaf_bests_p(struct xfs_dir2_leaf_tail *ltp)
 381 {
 382         return (__be16 *)ltp - be32_to_cpu(ltp->bestcount);
 383 }
 384
 385 /*
 386  * Convert dataptr to byte in file space
 387  */
 388 static inline xfs_dir2_off_t
 389 xfs_dir2_dataptr_to_byte(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
 390 {
 391         return (xfs_dir2_off_t)dp << XFS_DIR2_DATA_ALIGN_LOG;
 392 }
 393
 394 /*
 395  * Convert byte in file space to dataptr.  It had better be aligned.
 396  */
 397 static inline xfs_dir2_dataptr_t
 398 xfs_dir2_byte_to_dataptr(struct xfs_mount *mp, xfs_dir2_off_t by)
 399 {
 400         return (xfs_dir2_dataptr_t)(by >> XFS_DIR2_DATA_ALIGN_LOG);
 401 }
 402
 403 /*
 404  * Convert byte in space to (DB) block
 405  */
 406 static inline xfs_dir2_db_t
 407 xfs_dir2_byte_to_db(struct xfs_mount *mp, xfs_dir2_off_t by)
 408 {
 409         return (xfs_dir2_db_t)
 410                 (by >> (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog));
 411 }
 412
 413 /*
 414  * Convert dataptr to a block number
 415  */
 416 static inline xfs_dir2_db_t
 417 xfs_dir2_dataptr_to_db(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
 418 {
 419         return xfs_dir2_byte_to_db(mp, xfs_dir2_dataptr_to_byte(mp, dp));
 420 }
 421
 422 /*
 423  * Convert byte in space to offset in a block
 424  */
 425 static inline xfs_dir2_data_aoff_t
 426 xfs_dir2_byte_to_off(struct xfs_mount *mp, xfs_dir2_off_t by)
 427 {
 428         return (xfs_dir2_data_aoff_t)(by &
 429                 ((1 << (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog)) - 1));
 430 }
 431
 432 /*
 433  * Convert dataptr to a byte offset in a block
 434  */
 435 static inline xfs_dir2_data_aoff_t
 436 xfs_dir2_dataptr_to_off(struct xfs_mount *mp, xfs_dir2_dataptr_t dp)
 437 {
 438         return xfs_dir2_byte_to_off(mp, xfs_dir2_dataptr_to_byte(mp, dp));
 439 }
 440
 441 /*
 442  * Convert block and offset to byte in space
 443  */
 444 static inline xfs_dir2_off_t
 445 xfs_dir2_db_off_to_byte(struct xfs_mount *mp, xfs_dir2_db_t db,
 446                         xfs_dir2_data_aoff_t o)
 447 {
 448         return ((xfs_dir2_off_t)db <<
 449                 (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog)) + o;
 450 }
 451
 452 /*
 453  * Convert block (DB) to block (dablk)
 454  */
 455 static inline xfs_dablk_t
 456 xfs_dir2_db_to_da(struct xfs_mount *mp, xfs_dir2_db_t db)
 457 {
 458         return (xfs_dablk_t)(db << mp->m_sb.sb_dirblklog);
 459 }
 460
 461 /*
 462  * Convert byte in space to (DA) block
 463  */
 464 static inline xfs_dablk_t
 465 xfs_dir2_byte_to_da(struct xfs_mount *mp, xfs_dir2_off_t by)
 466 {
 467         return xfs_dir2_db_to_da(mp, xfs_dir2_byte_to_db(mp, by));
 468 }
 469
 470 /*
 471  * Convert block and offset to dataptr
 472  */
 473 static inline xfs_dir2_dataptr_t
 474 xfs_dir2_db_off_to_dataptr(struct xfs_mount *mp, xfs_dir2_db_t db,
 475                            xfs_dir2_data_aoff_t o)
 476 {
 477         return xfs_dir2_byte_to_dataptr(mp, xfs_dir2_db_off_to_byte(mp, db, o));
 478 }
 479
 480 /*
 481  * Convert block (dablk) to block (DB)
 482  */
 483 static inline xfs_dir2_db_t
 484 xfs_dir2_da_to_db(struct xfs_mount *mp, xfs_dablk_t da)
 485 {
 486         return (xfs_dir2_db_t)(da >> mp->m_sb.sb_dirblklog);
 487 }
 488
 489 /*
 490  * Convert block (dablk) to byte offset in space
 491  */
 492 static inline xfs_dir2_off_t
 493 xfs_dir2_da_to_byte(struct xfs_mount *mp, xfs_dablk_t da)
 494 {
 495         return xfs_dir2_db_off_to_byte(mp, xfs_dir2_da_to_db(mp, da), 0);
 496 }
 497
 498 /*
 499  * Free space block defintions for the node format.
 500  */
 501
 502 /*
 503  * Offset of the freespace index.
 504  */
 505 #define XFS_DIR2_FREE_SPACE     2
 506 #define XFS_DIR2_FREE_OFFSET    (XFS_DIR2_FREE_SPACE * XFS_DIR2_SPACE_SIZE)
 507 #define XFS_DIR2_FREE_FIRSTDB(mp)       \
 508         xfs_dir2_byte_to_db(mp, XFS_DIR2_FREE_OFFSET)
 509
 510 typedef struct xfs_dir2_free_hdr {
 511         __be32                  magic;          /* XFS_DIR2_FREE_MAGIC */
 512         __be32                  firstdb;        /* db of first entry */
 513         __be32                  nvalid;         /* count of valid entries */
 514         __be32                  nused;          /* count of used entries */
 515 } xfs_dir2_free_hdr_t;
 516
 517 typedef struct xfs_dir2_free {
 518         xfs_dir2_free_hdr_t     hdr;            /* block header */
 519         __be16                  bests[];        /* best free counts */
 520                                                 /* unused entries are -1 */
 521 } xfs_dir2_free_t;
 522
 523 static inline int xfs_dir2_free_max_bests(struct xfs_mount *mp)
 524 {
 525         return (mp->m_dirblksize - sizeof(struct xfs_dir2_free_hdr)) /
 526                 sizeof(xfs_dir2_data_off_t);
 527 }
 528
 529 /*
 530  * Convert data space db to the corresponding free db.
 531  */
 532 static inline xfs_dir2_db_t
 533 xfs_dir2_db_to_fdb(struct xfs_mount *mp, xfs_dir2_db_t db)
 534 {
 535         return XFS_DIR2_FREE_FIRSTDB(mp) + db / xfs_dir2_free_max_bests(mp);
 536 }
 537
 538 /*
 539  * Convert data space db to the corresponding index in a free db.
 540  */
 541 static inline int
 542 xfs_dir2_db_to_fdindex(struct xfs_mount *mp, xfs_dir2_db_t db)
 543 {
 544         return db % xfs_dir2_free_max_bests(mp);
 545 }
 546
 547 /*
 548  * Single block format.
 549  *
 550  * The single block format looks like the following drawing on disk:
 551  *
 552  *    +-------------------------------------------------+
 553  *    | xfs_dir2_data_hdr_t                             |
 554  *    +-------------------------------------------------+
 555  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
 556  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t |
 557  *    | xfs_dir2_data_entry_t OR xfs_dir2_data_unused_t :
 558  *    | ...                                             |
 559  *    +-------------------------------------------------+
 560  *    | unused space                                    |
 561  *    +-------------------------------------------------+
 562  *    | ...                                             |
 563  *    | xfs_dir2_leaf_entry_t                           |
 564  *    | xfs_dir2_leaf_entry_t                           |
 565  *    +-------------------------------------------------+
 566  *    | xfs_dir2_block_tail_t                           |
 567  *    +-------------------------------------------------+
 568  *
 569  * As all the entries are variable size structures the accessors below should
 570  * be used to iterate over them.
 571  */
 572
 573 typedef struct xfs_dir2_block_tail {
 574         __be32          count;                  /* count of leaf entries */
 575         __be32          stale;                  /* count of stale lf entries */
 576 } xfs_dir2_block_tail_t;
 577
 578 /*
 579  * Pointer to the leaf header embedded in a data block (1-block format)
 580  */
 581 static inline struct xfs_dir2_block_tail *
 582 xfs_dir2_block_tail_p(struct xfs_mount *mp, struct xfs_dir2_data_hdr *hdr)
 583 {
 584         return ((struct xfs_dir2_block_tail *)
 585                 ((char *)hdr + mp->m_dirblksize)) - 1;
 586 }
 587
 588 /*
 589  * Pointer to the leaf entries embedded in a data block (1-block format)
 590  */
 591 static inline struct xfs_dir2_leaf_entry *
 592 xfs_dir2_block_leaf_p(struct xfs_dir2_block_tail *btp)
 593 {
 594         return ((struct xfs_dir2_leaf_entry *)btp) - be32_to_cpu(btp->count);
 595 }
 596
 597 #endif /* __XFS_DIR2_FORMAT_H__ */