fs/xfs/xfs_dir2_data.c

   1 /*
   2  * Copyright (c) 2000-2002,2005 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 #include "xfs.h"
  19 #include "xfs_fs.h"
  20 #include "xfs_types.h"
  21 #include "xfs_log.h"
  22 #include "xfs_inum.h"
  23 #include "xfs_trans.h"
  24 #include "xfs_sb.h"
  25 #include "xfs_dir2.h"
  26 #include "xfs_dmapi.h"
  27 #include "xfs_mount.h"
  28 #include "xfs_da_btree.h"
  29 #include "xfs_bmap_btree.h"
  30 #include "xfs_dir2_sf.h"
  31 #include "xfs_attr_sf.h"
  32 #include "xfs_dinode.h"
  33 #include "xfs_inode.h"
  34 #include "xfs_dir2_data.h"
  35 #include "xfs_dir2_leaf.h"
  36 #include "xfs_dir2_block.h"
  37 #include "xfs_error.h"
  38
  39 #ifdef DEBUG
  40 /*
  41  * Check the consistency of the data block.
  42  * The input can also be a block-format directory.
  43  * Pop an assert if we find anything bad.
  44  */
  45 void
  46 xfs_dir2_data_check(
  47         xfs_inode_t             *dp,            /* incore inode pointer */
  48         xfs_dabuf_t             *bp)            /* data block's buffer */
  49 {
  50         xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
  51         xfs_dir2_data_free_t    *bf;            /* bestfree table */
  52         xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
  53         int                     count;          /* count of entries found */
  54         xfs_dir2_data_t         *d;             /* data block pointer */
  55         xfs_dir2_data_entry_t   *dep;           /* data entry */
  56         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
  57         xfs_dir2_data_unused_t  *dup;           /* unused entry */
  58         char                    *endp;          /* end of useful data */
  59         int                     freeseen;       /* mask of bestfrees seen */
  60         xfs_dahash_t            hash;           /* hash of current name */
  61         int                     i;              /* leaf index */
  62         int                     lastfree;       /* last entry was unused */
  63         xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
  64         xfs_mount_t             *mp;            /* filesystem mount point */
  65         char                    *p;             /* current data position */
  66         int                     stale;          /* count of stale leaves */
  67
  68         mp = dp->i_mount;
  69         d = bp->data;
  70         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
  71                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
  72         bf = d->hdr.bestfree;
  73         p = (char *)d->u;
  74         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
  75                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
  76                 lep = xfs_dir2_block_leaf_p(btp);
  77                 endp = (char *)lep;
  78         } else
  79                 endp = (char *)d + mp->m_dirblksize;
  80         count = lastfree = freeseen = 0;
  81         /*
  82          * Account for zero bestfree entries.
  83          */
  84         if (!bf[0].length) {
  85                 ASSERT(!bf[0].offset);
  86                 freeseen |= 1 << 0;
  87         }
  88         if (!bf[1].length) {
  89                 ASSERT(!bf[1].offset);
  90                 freeseen |= 1 << 1;
  91         }
  92         if (!bf[2].length) {
  93                 ASSERT(!bf[2].offset);
  94                 freeseen |= 1 << 2;
  95         }
  96         ASSERT(be16_to_cpu(bf[0].length) >= be16_to_cpu(bf[1].length));
  97         ASSERT(be16_to_cpu(bf[1].length) >= be16_to_cpu(bf[2].length));
  98         /*
  99          * Loop over the data/unused entries.
 100          */
 101         while (p < endp) {
 102                 dup = (xfs_dir2_data_unused_t *)p;
 103                 /*
 104                  * If it's unused, look for the space in the bestfree table.
 105                  * If we find it, account for that, else make sure it
 106                  * doesn't need to be there.
 107                  */
 108                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 109                         ASSERT(lastfree == 0);
 110                         ASSERT(be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
 111                                (char *)dup - (char *)d);
 112                         dfp = xfs_dir2_data_freefind(d, dup);
 113                         if (dfp) {
 114                                 i = (int)(dfp - bf);
 115                                 ASSERT((freeseen & (1 << i)) == 0);
 116                                 freeseen |= 1 << i;
 117                         } else {
 118                                 ASSERT(be16_to_cpu(dup->length) <=
 119                                        be16_to_cpu(bf[2].length));
 120                         }
 121                         p += be16_to_cpu(dup->length);
 122                         lastfree = 1;
 123                         continue;
 124                 }
 125                 /*
 126                  * It's a real entry.  Validate the fields.
 127                  * If this is a block directory then make sure it's
 128                  * in the leaf section of the block.
 129                  * The linear search is crude but this is DEBUG code.
 130                  */
 131                 dep = (xfs_dir2_data_entry_t *)p;
 132                 ASSERT(dep->namelen != 0);
 133                 ASSERT(xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)) == 0);
 134                 ASSERT(be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
 135                        (char *)dep - (char *)d);
 136                 count++;
 137                 lastfree = 0;
 138                 if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 139                         addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
 140                                 (xfs_dir2_data_aoff_t)
 141                                 ((char *)dep - (char *)d));
 142                         hash = xfs_da_hashname((char *)dep->name, dep->namelen);
 143                         for (i = 0; i < be32_to_cpu(btp->count); i++) {
 144                                 if (be32_to_cpu(lep[i].address) == addr &&
 145                                     be32_to_cpu(lep[i].hashval) == hash)
 146                                         break;
 147                         }
 148                         ASSERT(i < be32_to_cpu(btp->count));
 149                 }
 150                 p += xfs_dir2_data_entsize(dep->namelen);
 151         }
 152         /*
 153          * Need to have seen all the entries and all the bestfree slots.
 154          */
 155         ASSERT(freeseen == 7);
 156         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 157                 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
 158                         if (be32_to_cpu(lep[i].address) == XFS_DIR2_NULL_DATAPTR)
 159                                 stale++;
 160                         if (i > 0)
 161                                 ASSERT(be32_to_cpu(lep[i].hashval) >= be32_to_cpu(lep[i - 1].hashval));
 162                 }
 163                 ASSERT(count == be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
 164                 ASSERT(stale == be32_to_cpu(btp->stale));
 165         }
 166 }
 167 #endif
 168
 169 /*
 170  * Given a data block and an unused entry from that block,
 171  * return the bestfree entry if any that corresponds to it.
 172  */
 173 xfs_dir2_data_free_t *
 174 xfs_dir2_data_freefind(
 175         xfs_dir2_data_t         *d,             /* data block */
 176         xfs_dir2_data_unused_t  *dup)           /* data unused entry */
 177 {
 178         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
 179         xfs_dir2_data_aoff_t    off;            /* offset value needed */
 180 #if defined(DEBUG) && defined(__KERNEL__)
 181         int                     matched;        /* matched the value */
 182         int                     seenzero;       /* saw a 0 bestfree entry */
 183 #endif
 184
 185         off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)d);
 186 #if defined(DEBUG) && defined(__KERNEL__)
 187         /*
 188          * Validate some consistency in the bestfree table.
 189          * Check order, non-overlapping entries, and if we find the
 190          * one we're looking for it has to be exact.
 191          */
 192         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 193                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 194         for (dfp = &d->hdr.bestfree[0], seenzero = matched = 0;
 195              dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
 196              dfp++) {
 197                 if (!dfp->offset) {
 198                         ASSERT(!dfp->length);
 199                         seenzero = 1;
 200                         continue;
 201                 }
 202                 ASSERT(seenzero == 0);
 203                 if (be16_to_cpu(dfp->offset) == off) {
 204                         matched = 1;
 205                         ASSERT(dfp->length == dup->length);
 206                 } else if (off < be16_to_cpu(dfp->offset))
 207                         ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
 208                 else
 209                         ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
 210                 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
 211                 if (dfp > &d->hdr.bestfree[0])
 212                         ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
 213         }
 214 #endif
 215         /*
 216          * If this is smaller than the smallest bestfree entry,
 217          * it can't be there since they're sorted.
 218          */
 219         if (be16_to_cpu(dup->length) <
 220             be16_to_cpu(d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
 221                 return NULL;
 222         /*
 223          * Look at the three bestfree entries for our guy.
 224          */
 225         for (dfp = &d->hdr.bestfree[0];
 226              dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
 227              dfp++) {
 228                 if (!dfp->offset)
 229                         return NULL;
 230                 if (be16_to_cpu(dfp->offset) == off)
 231                         return dfp;
 232         }
 233         /*
 234          * Didn't find it.  This only happens if there are duplicate lengths.
 235          */
 236         return NULL;
 237 }
 238
 239 /*
 240  * Insert an unused-space entry into the bestfree table.
 241  */
 242 xfs_dir2_data_free_t *                          /* entry inserted */
 243 xfs_dir2_data_freeinsert(
 244         xfs_dir2_data_t         *d,             /* data block pointer */
 245         xfs_dir2_data_unused_t  *dup,           /* unused space */
 246         int                     *loghead)       /* log the data header (out) */
 247 {
 248         xfs_dir2_data_free_t    *dfp;           /* bestfree table pointer */
 249         xfs_dir2_data_free_t    new;            /* new bestfree entry */
 250
 251 #ifdef __KERNEL__
 252         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 253                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 254 #endif
 255         dfp = d->hdr.bestfree;
 256         new.length = dup->length;
 257         new.offset = cpu_to_be16((char *)dup - (char *)d);
 258         /*
 259          * Insert at position 0, 1, or 2; or not at all.
 260          */
 261         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
 262                 dfp[2] = dfp[1];
 263                 dfp[1] = dfp[0];
 264                 dfp[0] = new;
 265                 *loghead = 1;
 266                 return &dfp[0];
 267         }
 268         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
 269                 dfp[2] = dfp[1];
 270                 dfp[1] = new;
 271                 *loghead = 1;
 272                 return &dfp[1];
 273         }
 274         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
 275                 dfp[2] = new;
 276                 *loghead = 1;
 277                 return &dfp[2];
 278         }
 279         return NULL;
 280 }
 281
 282 /*
 283  * Remove a bestfree entry from the table.
 284  */
 285 STATIC void
 286 xfs_dir2_data_freeremove(
 287         xfs_dir2_data_t         *d,             /* data block pointer */
 288         xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
 289         int                     *loghead)       /* out: log data header */
 290 {
 291 #ifdef __KERNEL__
 292         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 293                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 294 #endif
 295         /*
 296          * It's the first entry, slide the next 2 up.
 297          */
 298         if (dfp == &d->hdr.bestfree[0]) {
 299                 d->hdr.bestfree[0] = d->hdr.bestfree[1];
 300                 d->hdr.bestfree[1] = d->hdr.bestfree[2];
 301         }
 302         /*
 303          * It's the second entry, slide the 3rd entry up.
 304          */
 305         else if (dfp == &d->hdr.bestfree[1])
 306                 d->hdr.bestfree[1] = d->hdr.bestfree[2];
 307         /*
 308          * Must be the last entry.
 309          */
 310         else
 311                 ASSERT(dfp == &d->hdr.bestfree[2]);
 312         /*
 313          * Clear the 3rd entry, must be zero now.
 314          */
 315         d->hdr.bestfree[2].length = 0;
 316         d->hdr.bestfree[2].offset = 0;
 317         *loghead = 1;
 318 }
 319
 320 /*
 321  * Given a data block, reconstruct its bestfree map.
 322  */
 323 void
 324 xfs_dir2_data_freescan(
 325         xfs_mount_t             *mp,            /* filesystem mount point */
 326         xfs_dir2_data_t         *d,             /* data block pointer */
 327         int                     *loghead)       /* out: log data header */
 328 {
 329         xfs_dir2_block_tail_t   *btp;           /* block tail */
 330         xfs_dir2_data_entry_t   *dep;           /* active data entry */
 331         xfs_dir2_data_unused_t  *dup;           /* unused data entry */
 332         char                    *endp;          /* end of block's data */
 333         char                    *p;             /* current entry pointer */
 334
 335 #ifdef __KERNEL__
 336         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 337                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 338 #endif
 339         /*
 340          * Start by clearing the table.
 341          */
 342         memset(d->hdr.bestfree, 0, sizeof(d->hdr.bestfree));
 343         *loghead = 1;
 344         /*
 345          * Set up pointers.
 346          */
 347         p = (char *)d->u;
 348         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 349                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 350                 endp = (char *)xfs_dir2_block_leaf_p(btp);
 351         } else
 352                 endp = (char *)d + mp->m_dirblksize;
 353         /*
 354          * Loop over the block's entries.
 355          */
 356         while (p < endp) {
 357                 dup = (xfs_dir2_data_unused_t *)p;
 358                 /*
 359                  * If it's a free entry, insert it.
 360                  */
 361                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 362                         ASSERT((char *)dup - (char *)d ==
 363                                be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 364                         xfs_dir2_data_freeinsert(d, dup, loghead);
 365                         p += be16_to_cpu(dup->length);
 366                 }
 367                 /*
 368                  * For active entries, check their tags and skip them.
 369                  */
 370                 else {
 371                         dep = (xfs_dir2_data_entry_t *)p;
 372                         ASSERT((char *)dep - (char *)d ==
 373                                be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
 374                         p += xfs_dir2_data_entsize(dep->namelen);
 375                 }
 376         }
 377 }
 378
 379 /*
 380  * Initialize a data block at the given block number in the directory.
 381  * Give back the buffer for the created block.
 382  */
 383 int                                             /* error */
 384 xfs_dir2_data_init(
 385         xfs_da_args_t           *args,          /* directory operation args */
 386         xfs_dir2_db_t           blkno,          /* logical dir block number */
 387         xfs_dabuf_t             **bpp)          /* output block buffer */
 388 {
 389         xfs_dabuf_t             *bp;            /* block buffer */
 390         xfs_dir2_data_t         *d;             /* pointer to block */
 391         xfs_inode_t             *dp;            /* incore directory inode */
 392         xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
 393         int                     error;          /* error return value */
 394         int                     i;              /* bestfree index */
 395         xfs_mount_t             *mp;            /* filesystem mount point */
 396         xfs_trans_t             *tp;            /* transaction pointer */
 397         int                     t;              /* temp */
 398
 399         dp = args->dp;
 400         mp = dp->i_mount;
 401         tp = args->trans;
 402         /*
 403          * Get the buffer set up for the block.
 404          */
 405         error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
 406                 XFS_DATA_FORK);
 407         if (error) {
 408                 return error;
 409         }
 410         ASSERT(bp != NULL);
 411         /*
 412          * Initialize the header.
 413          */
 414         d = bp->data;
 415         d->hdr.magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
 416         d->hdr.bestfree[0].offset = cpu_to_be16(sizeof(d->hdr));
 417         for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
 418                 d->hdr.bestfree[i].length = 0;
 419                 d->hdr.bestfree[i].offset = 0;
 420         }
 421         /*
 422          * Set up an unused entry for the block's body.
 423          */
 424         dup = &d->u[0].unused;
 425         dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 426
 427         t=mp->m_dirblksize - (uint)sizeof(d->hdr);
 428         d->hdr.bestfree[0].length = cpu_to_be16(t);
 429         dup->length = cpu_to_be16(t);
 430         *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)d);
 431         /*
 432          * Log it and return it.
 433          */
 434         xfs_dir2_data_log_header(tp, bp);
 435         xfs_dir2_data_log_unused(tp, bp, dup);
 436         *bpp = bp;
 437         return 0;
 438 }
 439
 440 /*
 441  * Log an active data entry from the block.
 442  */
 443 void
 444 xfs_dir2_data_log_entry(
 445         xfs_trans_t             *tp,            /* transaction pointer */
 446         xfs_dabuf_t             *bp,            /* block buffer */
 447         xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
 448 {
 449         xfs_dir2_data_t         *d;             /* data block pointer */
 450
 451         d = bp->data;
 452         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 453                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 454         xfs_da_log_buf(tp, bp, (uint)((char *)dep - (char *)d),
 455                 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
 456                        (char *)d - 1));
 457 }
 458
 459 /*
 460  * Log a data block header.
 461  */
 462 void
 463 xfs_dir2_data_log_header(
 464         xfs_trans_t             *tp,            /* transaction pointer */
 465         xfs_dabuf_t             *bp)            /* block buffer */
 466 {
 467         xfs_dir2_data_t         *d;             /* data block pointer */
 468
 469         d = bp->data;
 470         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 471                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 472         xfs_da_log_buf(tp, bp, (uint)((char *)&d->hdr - (char *)d),
 473                 (uint)(sizeof(d->hdr) - 1));
 474 }
 475
 476 /*
 477  * Log a data unused entry.
 478  */
 479 void
 480 xfs_dir2_data_log_unused(
 481         xfs_trans_t             *tp,            /* transaction pointer */
 482         xfs_dabuf_t             *bp,            /* block buffer */
 483         xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
 484 {
 485         xfs_dir2_data_t         *d;             /* data block pointer */
 486
 487         d = bp->data;
 488         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 489                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 490         /*
 491          * Log the first part of the unused entry.
 492          */
 493         xfs_da_log_buf(tp, bp, (uint)((char *)dup - (char *)d),
 494                 (uint)((char *)&dup->length + sizeof(dup->length) -
 495                        1 - (char *)d));
 496         /*
 497          * Log the end (tag) of the unused entry.
 498          */
 499         xfs_da_log_buf(tp, bp,
 500                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d),
 501                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d +
 502                        sizeof(xfs_dir2_data_off_t) - 1));
 503 }
 504
 505 /*
 506  * Make a byte range in the data block unused.
 507  * Its current contents are unimportant.
 508  */
 509 void
 510 xfs_dir2_data_make_free(
 511         xfs_trans_t             *tp,            /* transaction pointer */
 512         xfs_dabuf_t             *bp,            /* block buffer */
 513         xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
 514         xfs_dir2_data_aoff_t    len,            /* length in bytes */
 515         int                     *needlogp,      /* out: log header */
 516         int                     *needscanp)     /* out: regen bestfree */
 517 {
 518         xfs_dir2_data_t         *d;             /* data block pointer */
 519         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 520         char                    *endptr;        /* end of data area */
 521         xfs_mount_t             *mp;            /* filesystem mount point */
 522         int                     needscan;       /* need to regen bestfree */
 523         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 524         xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
 525         xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
 526
 527         mp = tp->t_mountp;
 528         d = bp->data;
 529         /*
 530          * Figure out where the end of the data area is.
 531          */
 532         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC)
 533                 endptr = (char *)d + mp->m_dirblksize;
 534         else {
 535                 xfs_dir2_block_tail_t   *btp;   /* block tail */
 536
 537                 ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 538                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 539                 endptr = (char *)xfs_dir2_block_leaf_p(btp);
 540         }
 541         /*
 542          * If this isn't the start of the block, then back up to
 543          * the previous entry and see if it's free.
 544          */
 545         if (offset > sizeof(d->hdr)) {
 546                 __be16                  *tagp;  /* tag just before us */
 547
 548                 tagp = (__be16 *)((char *)d + offset) - 1;
 549                 prevdup = (xfs_dir2_data_unused_t *)((char *)d + be16_to_cpu(*tagp));
 550                 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 551                         prevdup = NULL;
 552         } else
 553                 prevdup = NULL;
 554         /*
 555          * If this isn't the end of the block, see if the entry after
 556          * us is free.
 557          */
 558         if ((char *)d + offset + len < endptr) {
 559                 postdup =
 560                         (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 561                 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 562                         postdup = NULL;
 563         } else
 564                 postdup = NULL;
 565         ASSERT(*needscanp == 0);
 566         needscan = 0;
 567         /*
 568          * Previous and following entries are both free,
 569          * merge everything into a single free entry.
 570          */
 571         if (prevdup && postdup) {
 572                 xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
 573
 574                 /*
 575                  * See if prevdup and/or postdup are in bestfree table.
 576                  */
 577                 dfp = xfs_dir2_data_freefind(d, prevdup);
 578                 dfp2 = xfs_dir2_data_freefind(d, postdup);
 579                 /*
 580                  * We need a rescan unless there are exactly 2 free entries
 581                  * namely our two.  Then we know what's happening, otherwise
 582                  * since the third bestfree is there, there might be more
 583                  * entries.
 584                  */
 585                 needscan = (d->hdr.bestfree[2].length != 0);
 586                 /*
 587                  * Fix up the new big freespace.
 588                  */
 589                 be16_add(&prevdup->length, len + be16_to_cpu(postdup->length));
 590                 *xfs_dir2_data_unused_tag_p(prevdup) =
 591                         cpu_to_be16((char *)prevdup - (char *)d);
 592                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 593                 if (!needscan) {
 594                         /*
 595                          * Has to be the case that entries 0 and 1 are
 596                          * dfp and dfp2 (don't know which is which), and
 597                          * entry 2 is empty.
 598                          * Remove entry 1 first then entry 0.
 599                          */
 600                         ASSERT(dfp && dfp2);
 601                         if (dfp == &d->hdr.bestfree[1]) {
 602                                 dfp = &d->hdr.bestfree[0];
 603                                 ASSERT(dfp2 == dfp);
 604                                 dfp2 = &d->hdr.bestfree[1];
 605                         }
 606                         xfs_dir2_data_freeremove(d, dfp2, needlogp);
 607                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 608                         /*
 609                          * Now insert the new entry.
 610                          */
 611                         dfp = xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 612                         ASSERT(dfp == &d->hdr.bestfree[0]);
 613                         ASSERT(dfp->length == prevdup->length);
 614                         ASSERT(!dfp[1].length);
 615                         ASSERT(!dfp[2].length);
 616                 }
 617         }
 618         /*
 619          * The entry before us is free, merge with it.
 620          */
 621         else if (prevdup) {
 622                 dfp = xfs_dir2_data_freefind(d, prevdup);
 623                 be16_add(&prevdup->length, len);
 624                 *xfs_dir2_data_unused_tag_p(prevdup) =
 625                         cpu_to_be16((char *)prevdup - (char *)d);
 626                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 627                 /*
 628                  * If the previous entry was in the table, the new entry
 629                  * is longer, so it will be in the table too.  Remove
 630                  * the old one and add the new one.
 631                  */
 632                 if (dfp) {
 633                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 634                         (void)xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 635                 }
 636                 /*
 637                  * Otherwise we need a scan if the new entry is big enough.
 638                  */
 639                 else {
 640                         needscan = be16_to_cpu(prevdup->length) >
 641                                    be16_to_cpu(d->hdr.bestfree[2].length);
 642                 }
 643         }
 644         /*
 645          * The following entry is free, merge with it.
 646          */
 647         else if (postdup) {
 648                 dfp = xfs_dir2_data_freefind(d, postdup);
 649                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 650                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 651                 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
 652                 *xfs_dir2_data_unused_tag_p(newdup) =
 653                         cpu_to_be16((char *)newdup - (char *)d);
 654                 xfs_dir2_data_log_unused(tp, bp, newdup);
 655                 /*
 656                  * If the following entry was in the table, the new entry
 657                  * is longer, so it will be in the table too.  Remove
 658                  * the old one and add the new one.
 659                  */
 660                 if (dfp) {
 661                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 662                         (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 663                 }
 664                 /*
 665                  * Otherwise we need a scan if the new entry is big enough.
 666                  */
 667                 else {
 668                         needscan = be16_to_cpu(newdup->length) >
 669                                    be16_to_cpu(d->hdr.bestfree[2].length);
 670                 }
 671         }
 672         /*
 673          * Neither neighbor is free.  Make a new entry.
 674          */
 675         else {
 676                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 677                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 678                 newdup->length = cpu_to_be16(len);
 679                 *xfs_dir2_data_unused_tag_p(newdup) =
 680                         cpu_to_be16((char *)newdup - (char *)d);
 681                 xfs_dir2_data_log_unused(tp, bp, newdup);
 682                 (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 683         }
 684         *needscanp = needscan;
 685 }
 686
 687 /*
 688  * Take a byte range out of an existing unused space and make it un-free.
 689  */
 690 void
 691 xfs_dir2_data_use_free(
 692         xfs_trans_t             *tp,            /* transaction pointer */
 693         xfs_dabuf_t             *bp,            /* data block buffer */
 694         xfs_dir2_data_unused_t  *dup,           /* unused entry */
 695         xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
 696         xfs_dir2_data_aoff_t    len,            /* length to use */
 697         int                     *needlogp,      /* out: need to log header */
 698         int                     *needscanp)     /* out: need regen bestfree */
 699 {
 700         xfs_dir2_data_t         *d;             /* data block */
 701         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 702         int                     matchback;      /* matches end of freespace */
 703         int                     matchfront;     /* matches start of freespace */
 704         int                     needscan;       /* need to regen bestfree */
 705         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 706         xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
 707         int                     oldlen;         /* old unused entry's length */
 708
 709         d = bp->data;
 710         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 711                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 712         ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
 713         ASSERT(offset >= (char *)dup - (char *)d);
 714         ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)d);
 715         ASSERT((char *)dup - (char *)d == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 716         /*
 717          * Look up the entry in the bestfree table.
 718          */
 719         dfp = xfs_dir2_data_freefind(d, dup);
 720         oldlen = be16_to_cpu(dup->length);
 721         ASSERT(dfp || oldlen <= be16_to_cpu(d->hdr.bestfree[2].length));
 722         /*
 723          * Check for alignment with front and back of the entry.
 724          */
 725         matchfront = (char *)dup - (char *)d == offset;
 726         matchback = (char *)dup + oldlen - (char *)d == offset + len;
 727         ASSERT(*needscanp == 0);
 728         needscan = 0;
 729         /*
 730          * If we matched it exactly we just need to get rid of it from
 731          * the bestfree table.
 732          */
 733         if (matchfront && matchback) {
 734                 if (dfp) {
 735                         needscan = (d->hdr.bestfree[2].offset != 0);
 736                         if (!needscan)
 737                                 xfs_dir2_data_freeremove(d, dfp, needlogp);
 738                 }
 739         }
 740         /*
 741          * We match the first part of the entry.
 742          * Make a new entry with the remaining freespace.
 743          */
 744         else if (matchfront) {
 745                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 746                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 747                 newdup->length = cpu_to_be16(oldlen - len);
 748                 *xfs_dir2_data_unused_tag_p(newdup) =
 749                         cpu_to_be16((char *)newdup - (char *)d);
 750                 xfs_dir2_data_log_unused(tp, bp, newdup);
 751                 /*
 752                  * If it was in the table, remove it and add the new one.
 753                  */
 754                 if (dfp) {
 755                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 756                         dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 757                         ASSERT(dfp != NULL);
 758                         ASSERT(dfp->length == newdup->length);
 759                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 760                         /*
 761                          * If we got inserted at the last slot,
 762                          * that means we don't know if there was a better
 763                          * choice for the last slot, or not.  Rescan.
 764                          */
 765                         needscan = dfp == &d->hdr.bestfree[2];
 766                 }
 767         }
 768         /*
 769          * We match the last part of the entry.
 770          * Trim the allocated space off the tail of the entry.
 771          */
 772         else if (matchback) {
 773                 newdup = dup;
 774                 newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 775                 *xfs_dir2_data_unused_tag_p(newdup) =
 776                         cpu_to_be16((char *)newdup - (char *)d);
 777                 xfs_dir2_data_log_unused(tp, bp, newdup);
 778                 /*
 779                  * If it was in the table, remove it and add the new one.
 780                  */
 781                 if (dfp) {
 782                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 783                         dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 784                         ASSERT(dfp != NULL);
 785                         ASSERT(dfp->length == newdup->length);
 786                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 787                         /*
 788                          * If we got inserted at the last slot,
 789                          * that means we don't know if there was a better
 790                          * choice for the last slot, or not.  Rescan.
 791                          */
 792                         needscan = dfp == &d->hdr.bestfree[2];
 793                 }
 794         }
 795         /*
 796          * Poking out the middle of an entry.
 797          * Make two new entries.
 798          */
 799         else {
 800                 newdup = dup;
 801                 newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 802                 *xfs_dir2_data_unused_tag_p(newdup) =
 803                         cpu_to_be16((char *)newdup - (char *)d);
 804                 xfs_dir2_data_log_unused(tp, bp, newdup);
 805                 newdup2 = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 806                 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 807                 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
 808                 *xfs_dir2_data_unused_tag_p(newdup2) =
 809                         cpu_to_be16((char *)newdup2 - (char *)d);
 810                 xfs_dir2_data_log_unused(tp, bp, newdup2);
 811                 /*
 812                  * If the old entry was in the table, we need to scan
 813                  * if the 3rd entry was valid, since these entries
 814                  * are smaller than the old one.
 815                  * If we don't need to scan that means there were 1 or 2
 816                  * entries in the table, and removing the old and adding
 817                  * the 2 new will work.
 818                  */
 819                 if (dfp) {
 820                         needscan = (d->hdr.bestfree[2].length != 0);
 821                         if (!needscan) {
 822                                 xfs_dir2_data_freeremove(d, dfp, needlogp);
 823                                 (void)xfs_dir2_data_freeinsert(d, newdup,
 824                                         needlogp);
 825                                 (void)xfs_dir2_data_freeinsert(d, newdup2,
 826                                         needlogp);
 827                         }
 828                 }
 829         }
 830         *needscanp = needscan;
 831 }