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_ag.h"
  26 #include "xfs_dir2.h"
  27 #include "xfs_dmapi.h"
  28 #include "xfs_mount.h"
  29 #include "xfs_da_btree.h"
  30 #include "xfs_bmap_btree.h"
  31 #include "xfs_dir2_sf.h"
  32 #include "xfs_attr_sf.h"
  33 #include "xfs_dinode.h"
  34 #include "xfs_inode.h"
  35 #include "xfs_dir2_data.h"
  36 #include "xfs_dir2_leaf.h"
  37 #include "xfs_dir2_block.h"
  38 #include "xfs_error.h"
  39
  40 #ifdef DEBUG
  41 /*
  42  * Check the consistency of the data block.
  43  * The input can also be a block-format directory.
  44  * Pop an assert if we find anything bad.
  45  */
  46 void
  47 xfs_dir2_data_check(
  48         xfs_inode_t             *dp,            /* incore inode pointer */
  49         xfs_dabuf_t             *bp)            /* data block's buffer */
  50 {
  51         xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
  52         xfs_dir2_data_free_t    *bf;            /* bestfree table */
  53         xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
  54         int                     count;          /* count of entries found */
  55         xfs_dir2_data_t         *d;             /* data block pointer */
  56         xfs_dir2_data_entry_t   *dep;           /* data entry */
  57         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
  58         xfs_dir2_data_unused_t  *dup;           /* unused entry */
  59         char                    *endp;          /* end of useful data */
  60         int                     freeseen;       /* mask of bestfrees seen */
  61         xfs_dahash_t            hash;           /* hash of current name */
  62         int                     i;              /* leaf index */
  63         int                     lastfree;       /* last entry was unused */
  64         xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
  65         xfs_mount_t             *mp;            /* filesystem mount point */
  66         char                    *p;             /* current data position */
  67         int                     stale;          /* count of stale leaves */
  68
  69         mp = dp->i_mount;
  70         d = bp->data;
  71         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
  72                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
  73         bf = d->hdr.bestfree;
  74         p = (char *)d->u;
  75         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
  76                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
  77                 lep = xfs_dir2_block_leaf_p(btp);
  78                 endp = (char *)lep;
  79         } else
  80                 endp = (char *)d + mp->m_dirblksize;
  81         count = lastfree = freeseen = 0;
  82         /*
  83          * Account for zero bestfree entries.
  84          */
  85         if (!bf[0].length) {
  86                 ASSERT(!bf[0].offset);
  87                 freeseen |= 1 << 0;
  88         }
  89         if (!bf[1].length) {
  90                 ASSERT(!bf[1].offset);
  91                 freeseen |= 1 << 1;
  92         }
  93         if (!bf[2].length) {
  94                 ASSERT(!bf[2].offset);
  95                 freeseen |= 1 << 2;
  96         }
  97         ASSERT(be16_to_cpu(bf[0].length) >= be16_to_cpu(bf[1].length));
  98         ASSERT(be16_to_cpu(bf[1].length) >= be16_to_cpu(bf[2].length));
  99         /*
 100          * Loop over the data/unused entries.
 101          */
 102         while (p < endp) {
 103                 dup = (xfs_dir2_data_unused_t *)p;
 104                 /*
 105                  * If it's unused, look for the space in the bestfree table.
 106                  * If we find it, account for that, else make sure it
 107                  * doesn't need to be there.
 108                  */
 109                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 110                         ASSERT(lastfree == 0);
 111                         ASSERT(be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
 112                                (char *)dup - (char *)d);
 113                         dfp = xfs_dir2_data_freefind(d, dup);
 114                         if (dfp) {
 115                                 i = (int)(dfp - bf);
 116                                 ASSERT((freeseen & (1 << i)) == 0);
 117                                 freeseen |= 1 << i;
 118                         } else {
 119                                 ASSERT(be16_to_cpu(dup->length) <=
 120                                        be16_to_cpu(bf[2].length));
 121                         }
 122                         p += be16_to_cpu(dup->length);
 123                         lastfree = 1;
 124                         continue;
 125                 }
 126                 /*
 127                  * It's a real entry.  Validate the fields.
 128                  * If this is a block directory then make sure it's
 129                  * in the leaf section of the block.
 130                  * The linear search is crude but this is DEBUG code.
 131                  */
 132                 dep = (xfs_dir2_data_entry_t *)p;
 133                 ASSERT(dep->namelen != 0);
 134                 ASSERT(xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)) == 0);
 135                 ASSERT(be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
 136                        (char *)dep - (char *)d);
 137                 count++;
 138                 lastfree = 0;
 139                 if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 140                         addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
 141                                 (xfs_dir2_data_aoff_t)
 142                                 ((char *)dep - (char *)d));
 143                         hash = xfs_da_hashname((char *)dep->name, dep->namelen);
 144                         for (i = 0; i < be32_to_cpu(btp->count); i++) {
 145                                 if (be32_to_cpu(lep[i].address) == addr &&
 146                                     be32_to_cpu(lep[i].hashval) == hash)
 147                                         break;
 148                         }
 149                         ASSERT(i < be32_to_cpu(btp->count));
 150                 }
 151                 p += xfs_dir2_data_entsize(dep->namelen);
 152         }
 153         /*
 154          * Need to have seen all the entries and all the bestfree slots.
 155          */
 156         ASSERT(freeseen == 7);
 157         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 158                 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
 159                         if (be32_to_cpu(lep[i].address) == XFS_DIR2_NULL_DATAPTR)
 160                                 stale++;
 161                         if (i > 0)
 162                                 ASSERT(be32_to_cpu(lep[i].hashval) >= be32_to_cpu(lep[i - 1].hashval));
 163                 }
 164                 ASSERT(count == be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
 165                 ASSERT(stale == be32_to_cpu(btp->stale));
 166         }
 167 }
 168 #endif
 169
 170 /*
 171  * Given a data block and an unused entry from that block,
 172  * return the bestfree entry if any that corresponds to it.
 173  */
 174 xfs_dir2_data_free_t *
 175 xfs_dir2_data_freefind(
 176         xfs_dir2_data_t         *d,             /* data block */
 177         xfs_dir2_data_unused_t  *dup)           /* data unused entry */
 178 {
 179         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
 180         xfs_dir2_data_aoff_t    off;            /* offset value needed */
 181 #if defined(DEBUG) && defined(__KERNEL__)
 182         int                     matched;        /* matched the value */
 183         int                     seenzero;       /* saw a 0 bestfree entry */
 184 #endif
 185
 186         off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)d);
 187 #if defined(DEBUG) && defined(__KERNEL__)
 188         /*
 189          * Validate some consistency in the bestfree table.
 190          * Check order, non-overlapping entries, and if we find the
 191          * one we're looking for it has to be exact.
 192          */
 193         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 194                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 195         for (dfp = &d->hdr.bestfree[0], seenzero = matched = 0;
 196              dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
 197              dfp++) {
 198                 if (!dfp->offset) {
 199                         ASSERT(!dfp->length);
 200                         seenzero = 1;
 201                         continue;
 202                 }
 203                 ASSERT(seenzero == 0);
 204                 if (be16_to_cpu(dfp->offset) == off) {
 205                         matched = 1;
 206                         ASSERT(dfp->length == dup->length);
 207                 } else if (off < be16_to_cpu(dfp->offset))
 208                         ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
 209                 else
 210                         ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
 211                 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
 212                 if (dfp > &d->hdr.bestfree[0])
 213                         ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
 214         }
 215 #endif
 216         /*
 217          * If this is smaller than the smallest bestfree entry,
 218          * it can't be there since they're sorted.
 219          */
 220         if (be16_to_cpu(dup->length) <
 221             be16_to_cpu(d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
 222                 return NULL;
 223         /*
 224          * Look at the three bestfree entries for our guy.
 225          */
 226         for (dfp = &d->hdr.bestfree[0];
 227              dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
 228              dfp++) {
 229                 if (!dfp->offset)
 230                         return NULL;
 231                 if (be16_to_cpu(dfp->offset) == off)
 232                         return dfp;
 233         }
 234         /*
 235          * Didn't find it.  This only happens if there are duplicate lengths.
 236          */
 237         return NULL;
 238 }
 239
 240 /*
 241  * Insert an unused-space entry into the bestfree table.
 242  */
 243 xfs_dir2_data_free_t *                          /* entry inserted */
 244 xfs_dir2_data_freeinsert(
 245         xfs_dir2_data_t         *d,             /* data block pointer */
 246         xfs_dir2_data_unused_t  *dup,           /* unused space */
 247         int                     *loghead)       /* log the data header (out) */
 248 {
 249         xfs_dir2_data_free_t    *dfp;           /* bestfree table pointer */
 250         xfs_dir2_data_free_t    new;            /* new bestfree entry */
 251
 252 #ifdef __KERNEL__
 253         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 254                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 255 #endif
 256         dfp = d->hdr.bestfree;
 257         new.length = dup->length;
 258         new.offset = cpu_to_be16((char *)dup - (char *)d);
 259         /*
 260          * Insert at position 0, 1, or 2; or not at all.
 261          */
 262         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
 263                 dfp[2] = dfp[1];
 264                 dfp[1] = dfp[0];
 265                 dfp[0] = new;
 266                 *loghead = 1;
 267                 return &dfp[0];
 268         }
 269         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
 270                 dfp[2] = dfp[1];
 271                 dfp[1] = new;
 272                 *loghead = 1;
 273                 return &dfp[1];
 274         }
 275         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
 276                 dfp[2] = new;
 277                 *loghead = 1;
 278                 return &dfp[2];
 279         }
 280         return NULL;
 281 }
 282
 283 /*
 284  * Remove a bestfree entry from the table.
 285  */
 286 STATIC void
 287 xfs_dir2_data_freeremove(
 288         xfs_dir2_data_t         *d,             /* data block pointer */
 289         xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
 290         int                     *loghead)       /* out: log data header */
 291 {
 292 #ifdef __KERNEL__
 293         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 294                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 295 #endif
 296         /*
 297          * It's the first entry, slide the next 2 up.
 298          */
 299         if (dfp == &d->hdr.bestfree[0]) {
 300                 d->hdr.bestfree[0] = d->hdr.bestfree[1];
 301                 d->hdr.bestfree[1] = d->hdr.bestfree[2];
 302         }
 303         /*
 304          * It's the second entry, slide the 3rd entry up.
 305          */
 306         else if (dfp == &d->hdr.bestfree[1])
 307                 d->hdr.bestfree[1] = d->hdr.bestfree[2];
 308         /*
 309          * Must be the last entry.
 310          */
 311         else
 312                 ASSERT(dfp == &d->hdr.bestfree[2]);
 313         /*
 314          * Clear the 3rd entry, must be zero now.
 315          */
 316         d->hdr.bestfree[2].length = 0;
 317         d->hdr.bestfree[2].offset = 0;
 318         *loghead = 1;
 319 }
 320
 321 /*
 322  * Given a data block, reconstruct its bestfree map.
 323  */
 324 void
 325 xfs_dir2_data_freescan(
 326         xfs_mount_t             *mp,            /* filesystem mount point */
 327         xfs_dir2_data_t         *d,             /* data block pointer */
 328         int                     *loghead)       /* out: log data header */
 329 {
 330         xfs_dir2_block_tail_t   *btp;           /* block tail */
 331         xfs_dir2_data_entry_t   *dep;           /* active data entry */
 332         xfs_dir2_data_unused_t  *dup;           /* unused data entry */
 333         char                    *endp;          /* end of block's data */
 334         char                    *p;             /* current entry pointer */
 335
 336 #ifdef __KERNEL__
 337         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 338                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 339 #endif
 340         /*
 341          * Start by clearing the table.
 342          */
 343         memset(d->hdr.bestfree, 0, sizeof(d->hdr.bestfree));
 344         *loghead = 1;
 345         /*
 346          * Set up pointers.
 347          */
 348         p = (char *)d->u;
 349         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 350                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 351                 endp = (char *)xfs_dir2_block_leaf_p(btp);
 352         } else
 353                 endp = (char *)d + mp->m_dirblksize;
 354         /*
 355          * Loop over the block's entries.
 356          */
 357         while (p < endp) {
 358                 dup = (xfs_dir2_data_unused_t *)p;
 359                 /*
 360                  * If it's a free entry, insert it.
 361                  */
 362                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 363                         ASSERT((char *)dup - (char *)d ==
 364                                be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 365                         xfs_dir2_data_freeinsert(d, dup, loghead);
 366                         p += be16_to_cpu(dup->length);
 367                 }
 368                 /*
 369                  * For active entries, check their tags and skip them.
 370                  */
 371                 else {
 372                         dep = (xfs_dir2_data_entry_t *)p;
 373                         ASSERT((char *)dep - (char *)d ==
 374                                be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
 375                         p += xfs_dir2_data_entsize(dep->namelen);
 376                 }
 377         }
 378 }
 379
 380 /*
 381  * Initialize a data block at the given block number in the directory.
 382  * Give back the buffer for the created block.
 383  */
 384 int                                             /* error */
 385 xfs_dir2_data_init(
 386         xfs_da_args_t           *args,          /* directory operation args */
 387         xfs_dir2_db_t           blkno,          /* logical dir block number */
 388         xfs_dabuf_t             **bpp)          /* output block buffer */
 389 {
 390         xfs_dabuf_t             *bp;            /* block buffer */
 391         xfs_dir2_data_t         *d;             /* pointer to block */
 392         xfs_inode_t             *dp;            /* incore directory inode */
 393         xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
 394         int                     error;          /* error return value */
 395         int                     i;              /* bestfree index */
 396         xfs_mount_t             *mp;            /* filesystem mount point */
 397         xfs_trans_t             *tp;            /* transaction pointer */
 398         int                     t;              /* temp */
 399
 400         dp = args->dp;
 401         mp = dp->i_mount;
 402         tp = args->trans;
 403         /*
 404          * Get the buffer set up for the block.
 405          */
 406         error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
 407                 XFS_DATA_FORK);
 408         if (error) {
 409                 return error;
 410         }
 411         ASSERT(bp != NULL);
 412         /*
 413          * Initialize the header.
 414          */
 415         d = bp->data;
 416         d->hdr.magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
 417         d->hdr.bestfree[0].offset = cpu_to_be16(sizeof(d->hdr));
 418         for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
 419                 d->hdr.bestfree[i].length = 0;
 420                 d->hdr.bestfree[i].offset = 0;
 421         }
 422         /*
 423          * Set up an unused entry for the block's body.
 424          */
 425         dup = &d->u[0].unused;
 426         dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 427
 428         t=mp->m_dirblksize - (uint)sizeof(d->hdr);
 429         d->hdr.bestfree[0].length = cpu_to_be16(t);
 430         dup->length = cpu_to_be16(t);
 431         *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)d);
 432         /*
 433          * Log it and return it.
 434          */
 435         xfs_dir2_data_log_header(tp, bp);
 436         xfs_dir2_data_log_unused(tp, bp, dup);
 437         *bpp = bp;
 438         return 0;
 439 }
 440
 441 /*
 442  * Log an active data entry from the block.
 443  */
 444 void
 445 xfs_dir2_data_log_entry(
 446         xfs_trans_t             *tp,            /* transaction pointer */
 447         xfs_dabuf_t             *bp,            /* block buffer */
 448         xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
 449 {
 450         xfs_dir2_data_t         *d;             /* data block pointer */
 451
 452         d = bp->data;
 453         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 454                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 455         xfs_da_log_buf(tp, bp, (uint)((char *)dep - (char *)d),
 456                 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
 457                        (char *)d - 1));
 458 }
 459
 460 /*
 461  * Log a data block header.
 462  */
 463 void
 464 xfs_dir2_data_log_header(
 465         xfs_trans_t             *tp,            /* transaction pointer */
 466         xfs_dabuf_t             *bp)            /* block buffer */
 467 {
 468         xfs_dir2_data_t         *d;             /* data block pointer */
 469
 470         d = bp->data;
 471         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 472                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 473         xfs_da_log_buf(tp, bp, (uint)((char *)&d->hdr - (char *)d),
 474                 (uint)(sizeof(d->hdr) - 1));
 475 }
 476
 477 /*
 478  * Log a data unused entry.
 479  */
 480 void
 481 xfs_dir2_data_log_unused(
 482         xfs_trans_t             *tp,            /* transaction pointer */
 483         xfs_dabuf_t             *bp,            /* block buffer */
 484         xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
 485 {
 486         xfs_dir2_data_t         *d;             /* data block pointer */
 487
 488         d = bp->data;
 489         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 490                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 491         /*
 492          * Log the first part of the unused entry.
 493          */
 494         xfs_da_log_buf(tp, bp, (uint)((char *)dup - (char *)d),
 495                 (uint)((char *)&dup->length + sizeof(dup->length) -
 496                        1 - (char *)d));
 497         /*
 498          * Log the end (tag) of the unused entry.
 499          */
 500         xfs_da_log_buf(tp, bp,
 501                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d),
 502                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d +
 503                        sizeof(xfs_dir2_data_off_t) - 1));
 504 }
 505
 506 /*
 507  * Make a byte range in the data block unused.
 508  * Its current contents are unimportant.
 509  */
 510 void
 511 xfs_dir2_data_make_free(
 512         xfs_trans_t             *tp,            /* transaction pointer */
 513         xfs_dabuf_t             *bp,            /* block buffer */
 514         xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
 515         xfs_dir2_data_aoff_t    len,            /* length in bytes */
 516         int                     *needlogp,      /* out: log header */
 517         int                     *needscanp)     /* out: regen bestfree */
 518 {
 519         xfs_dir2_data_t         *d;             /* data block pointer */
 520         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 521         char                    *endptr;        /* end of data area */
 522         xfs_mount_t             *mp;            /* filesystem mount point */
 523         int                     needscan;       /* need to regen bestfree */
 524         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 525         xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
 526         xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
 527
 528         mp = tp->t_mountp;
 529         d = bp->data;
 530         /*
 531          * Figure out where the end of the data area is.
 532          */
 533         if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC)
 534                 endptr = (char *)d + mp->m_dirblksize;
 535         else {
 536                 xfs_dir2_block_tail_t   *btp;   /* block tail */
 537
 538                 ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 539                 btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 540                 endptr = (char *)xfs_dir2_block_leaf_p(btp);
 541         }
 542         /*
 543          * If this isn't the start of the block, then back up to
 544          * the previous entry and see if it's free.
 545          */
 546         if (offset > sizeof(d->hdr)) {
 547                 __be16                  *tagp;  /* tag just before us */
 548
 549                 tagp = (__be16 *)((char *)d + offset) - 1;
 550                 prevdup = (xfs_dir2_data_unused_t *)((char *)d + be16_to_cpu(*tagp));
 551                 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 552                         prevdup = NULL;
 553         } else
 554                 prevdup = NULL;
 555         /*
 556          * If this isn't the end of the block, see if the entry after
 557          * us is free.
 558          */
 559         if ((char *)d + offset + len < endptr) {
 560                 postdup =
 561                         (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 562                 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 563                         postdup = NULL;
 564         } else
 565                 postdup = NULL;
 566         ASSERT(*needscanp == 0);
 567         needscan = 0;
 568         /*
 569          * Previous and following entries are both free,
 570          * merge everything into a single free entry.
 571          */
 572         if (prevdup && postdup) {
 573                 xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
 574
 575                 /*
 576                  * See if prevdup and/or postdup are in bestfree table.
 577                  */
 578                 dfp = xfs_dir2_data_freefind(d, prevdup);
 579                 dfp2 = xfs_dir2_data_freefind(d, postdup);
 580                 /*
 581                  * We need a rescan unless there are exactly 2 free entries
 582                  * namely our two.  Then we know what's happening, otherwise
 583                  * since the third bestfree is there, there might be more
 584                  * entries.
 585                  */
 586                 needscan = (d->hdr.bestfree[2].length != 0);
 587                 /*
 588                  * Fix up the new big freespace.
 589                  */
 590                 be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
 591                 *xfs_dir2_data_unused_tag_p(prevdup) =
 592                         cpu_to_be16((char *)prevdup - (char *)d);
 593                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 594                 if (!needscan) {
 595                         /*
 596                          * Has to be the case that entries 0 and 1 are
 597                          * dfp and dfp2 (don't know which is which), and
 598                          * entry 2 is empty.
 599                          * Remove entry 1 first then entry 0.
 600                          */
 601                         ASSERT(dfp && dfp2);
 602                         if (dfp == &d->hdr.bestfree[1]) {
 603                                 dfp = &d->hdr.bestfree[0];
 604                                 ASSERT(dfp2 == dfp);
 605                                 dfp2 = &d->hdr.bestfree[1];
 606                         }
 607                         xfs_dir2_data_freeremove(d, dfp2, needlogp);
 608                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 609                         /*
 610                          * Now insert the new entry.
 611                          */
 612                         dfp = xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 613                         ASSERT(dfp == &d->hdr.bestfree[0]);
 614                         ASSERT(dfp->length == prevdup->length);
 615                         ASSERT(!dfp[1].length);
 616                         ASSERT(!dfp[2].length);
 617                 }
 618         }
 619         /*
 620          * The entry before us is free, merge with it.
 621          */
 622         else if (prevdup) {
 623                 dfp = xfs_dir2_data_freefind(d, prevdup);
 624                 be16_add_cpu(&prevdup->length, len);
 625                 *xfs_dir2_data_unused_tag_p(prevdup) =
 626                         cpu_to_be16((char *)prevdup - (char *)d);
 627                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 628                 /*
 629                  * If the previous entry was in the table, the new entry
 630                  * is longer, so it will be in the table too.  Remove
 631                  * the old one and add the new one.
 632                  */
 633                 if (dfp) {
 634                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 635                         (void)xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 636                 }
 637                 /*
 638                  * Otherwise we need a scan if the new entry is big enough.
 639                  */
 640                 else {
 641                         needscan = be16_to_cpu(prevdup->length) >
 642                                    be16_to_cpu(d->hdr.bestfree[2].length);
 643                 }
 644         }
 645         /*
 646          * The following entry is free, merge with it.
 647          */
 648         else if (postdup) {
 649                 dfp = xfs_dir2_data_freefind(d, postdup);
 650                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 651                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 652                 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
 653                 *xfs_dir2_data_unused_tag_p(newdup) =
 654                         cpu_to_be16((char *)newdup - (char *)d);
 655                 xfs_dir2_data_log_unused(tp, bp, newdup);
 656                 /*
 657                  * If the following entry was in the table, the new entry
 658                  * is longer, so it will be in the table too.  Remove
 659                  * the old one and add the new one.
 660                  */
 661                 if (dfp) {
 662                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 663                         (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 664                 }
 665                 /*
 666                  * Otherwise we need a scan if the new entry is big enough.
 667                  */
 668                 else {
 669                         needscan = be16_to_cpu(newdup->length) >
 670                                    be16_to_cpu(d->hdr.bestfree[2].length);
 671                 }
 672         }
 673         /*
 674          * Neither neighbor is free.  Make a new entry.
 675          */
 676         else {
 677                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 678                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 679                 newdup->length = cpu_to_be16(len);
 680                 *xfs_dir2_data_unused_tag_p(newdup) =
 681                         cpu_to_be16((char *)newdup - (char *)d);
 682                 xfs_dir2_data_log_unused(tp, bp, newdup);
 683                 (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 684         }
 685         *needscanp = needscan;
 686 }
 687
 688 /*
 689  * Take a byte range out of an existing unused space and make it un-free.
 690  */
 691 void
 692 xfs_dir2_data_use_free(
 693         xfs_trans_t             *tp,            /* transaction pointer */
 694         xfs_dabuf_t             *bp,            /* data block buffer */
 695         xfs_dir2_data_unused_t  *dup,           /* unused entry */
 696         xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
 697         xfs_dir2_data_aoff_t    len,            /* length to use */
 698         int                     *needlogp,      /* out: need to log header */
 699         int                     *needscanp)     /* out: need regen bestfree */
 700 {
 701         xfs_dir2_data_t         *d;             /* data block */
 702         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 703         int                     matchback;      /* matches end of freespace */
 704         int                     matchfront;     /* matches start of freespace */
 705         int                     needscan;       /* need to regen bestfree */
 706         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 707         xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
 708         int                     oldlen;         /* old unused entry's length */
 709
 710         d = bp->data;
 711         ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 712                be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 713         ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
 714         ASSERT(offset >= (char *)dup - (char *)d);
 715         ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)d);
 716         ASSERT((char *)dup - (char *)d == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 717         /*
 718          * Look up the entry in the bestfree table.
 719          */
 720         dfp = xfs_dir2_data_freefind(d, dup);
 721         oldlen = be16_to_cpu(dup->length);
 722         ASSERT(dfp || oldlen <= be16_to_cpu(d->hdr.bestfree[2].length));
 723         /*
 724          * Check for alignment with front and back of the entry.
 725          */
 726         matchfront = (char *)dup - (char *)d == offset;
 727         matchback = (char *)dup + oldlen - (char *)d == offset + len;
 728         ASSERT(*needscanp == 0);
 729         needscan = 0;
 730         /*
 731          * If we matched it exactly we just need to get rid of it from
 732          * the bestfree table.
 733          */
 734         if (matchfront && matchback) {
 735                 if (dfp) {
 736                         needscan = (d->hdr.bestfree[2].offset != 0);
 737                         if (!needscan)
 738                                 xfs_dir2_data_freeremove(d, dfp, needlogp);
 739                 }
 740         }
 741         /*
 742          * We match the first part of the entry.
 743          * Make a new entry with the remaining freespace.
 744          */
 745         else if (matchfront) {
 746                 newdup = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 747                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 748                 newdup->length = cpu_to_be16(oldlen - len);
 749                 *xfs_dir2_data_unused_tag_p(newdup) =
 750                         cpu_to_be16((char *)newdup - (char *)d);
 751                 xfs_dir2_data_log_unused(tp, bp, newdup);
 752                 /*
 753                  * If it was in the table, remove it and add the new one.
 754                  */
 755                 if (dfp) {
 756                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 757                         dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 758                         ASSERT(dfp != NULL);
 759                         ASSERT(dfp->length == newdup->length);
 760                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 761                         /*
 762                          * If we got inserted at the last slot,
 763                          * that means we don't know if there was a better
 764                          * choice for the last slot, or not.  Rescan.
 765                          */
 766                         needscan = dfp == &d->hdr.bestfree[2];
 767                 }
 768         }
 769         /*
 770          * We match the last part of the entry.
 771          * Trim the allocated space off the tail of the entry.
 772          */
 773         else if (matchback) {
 774                 newdup = dup;
 775                 newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 776                 *xfs_dir2_data_unused_tag_p(newdup) =
 777                         cpu_to_be16((char *)newdup - (char *)d);
 778                 xfs_dir2_data_log_unused(tp, bp, newdup);
 779                 /*
 780                  * If it was in the table, remove it and add the new one.
 781                  */
 782                 if (dfp) {
 783                         xfs_dir2_data_freeremove(d, dfp, needlogp);
 784                         dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 785                         ASSERT(dfp != NULL);
 786                         ASSERT(dfp->length == newdup->length);
 787                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 788                         /*
 789                          * If we got inserted at the last slot,
 790                          * that means we don't know if there was a better
 791                          * choice for the last slot, or not.  Rescan.
 792                          */
 793                         needscan = dfp == &d->hdr.bestfree[2];
 794                 }
 795         }
 796         /*
 797          * Poking out the middle of an entry.
 798          * Make two new entries.
 799          */
 800         else {
 801                 newdup = dup;
 802                 newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 803                 *xfs_dir2_data_unused_tag_p(newdup) =
 804                         cpu_to_be16((char *)newdup - (char *)d);
 805                 xfs_dir2_data_log_unused(tp, bp, newdup);
 806                 newdup2 = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 807                 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 808                 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
 809                 *xfs_dir2_data_unused_tag_p(newdup2) =
 810                         cpu_to_be16((char *)newdup2 - (char *)d);
 811                 xfs_dir2_data_log_unused(tp, bp, newdup2);
 812                 /*
 813                  * If the old entry was in the table, we need to scan
 814                  * if the 3rd entry was valid, since these entries
 815                  * are smaller than the old one.
 816                  * If we don't need to scan that means there were 1 or 2
 817                  * entries in the table, and removing the old and adding
 818                  * the 2 new will work.
 819                  */
 820                 if (dfp) {
 821                         needscan = (d->hdr.bestfree[2].length != 0);
 822                         if (!needscan) {
 823                                 xfs_dir2_data_freeremove(d, dfp, needlogp);
 824                                 (void)xfs_dir2_data_freeinsert(d, newdup,
 825                                         needlogp);
 826                                 (void)xfs_dir2_data_freeinsert(d, newdup2,
 827                                         needlogp);
 828                         }
 829                 }
 830         }
 831         *needscanp = needscan;
 832 }