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_trans.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_ag.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_da_btree.h"
  27 #include "xfs_bmap_btree.h"
  28 #include "xfs_dinode.h"
  29 #include "xfs_inode.h"
  30 #include "xfs_dir2_format.h"
  31 #include "xfs_dir2_priv.h"
  32 #include "xfs_error.h"
  33
  34 STATIC xfs_dir2_data_free_t *
  35 xfs_dir2_data_freefind(xfs_dir2_data_hdr_t *hdr, xfs_dir2_data_unused_t *dup);
  36
  37 #ifdef DEBUG
  38 /*
  39  * Check the consistency of the data block.
  40  * The input can also be a block-format directory.
  41  * Pop an assert if we find anything bad.
  42  */
  43 void
  44 xfs_dir2_data_check(
  45         struct xfs_inode        *dp,            /* incore inode pointer */
  46         struct xfs_buf          *bp)            /* data block's buffer */
  47 {
  48         xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
  49         xfs_dir2_data_free_t    *bf;            /* bestfree table */
  50         xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
  51         int                     count;          /* count of entries found */
  52         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
  53         xfs_dir2_data_entry_t   *dep;           /* data entry */
  54         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
  55         xfs_dir2_data_unused_t  *dup;           /* unused entry */
  56         char                    *endp;          /* end of useful data */
  57         int                     freeseen;       /* mask of bestfrees seen */
  58         xfs_dahash_t            hash;           /* hash of current name */
  59         int                     i;              /* leaf index */
  60         int                     lastfree;       /* last entry was unused */
  61         xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
  62         xfs_mount_t             *mp;            /* filesystem mount point */
  63         char                    *p;             /* current data position */
  64         int                     stale;          /* count of stale leaves */
  65         struct xfs_name         name;
  66
  67         mp = dp->i_mount;
  68         hdr = bp->b_addr;
  69         bf = hdr->bestfree;
  70         p = (char *)(hdr + 1);
  71
  72         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
  73                 btp = xfs_dir2_block_tail_p(mp, hdr);
  74                 lep = xfs_dir2_block_leaf_p(btp);
  75                 endp = (char *)lep;
  76         } else {
  77                 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC));
  78                 endp = (char *)hdr + mp->m_dirblksize;
  79         }
  80
  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 *)hdr);
 113                         dfp = xfs_dir2_data_freefind(hdr, 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 *)hdr);
 137                 count++;
 138                 lastfree = 0;
 139                 if (hdr->magic == cpu_to_be32(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 *)hdr));
 143                         name.name = dep->name;
 144                         name.len = dep->namelen;
 145                         hash = mp->m_dirnameops->hashname(&name);
 146                         for (i = 0; i < be32_to_cpu(btp->count); i++) {
 147                                 if (be32_to_cpu(lep[i].address) == addr &&
 148                                     be32_to_cpu(lep[i].hashval) == hash)
 149                                         break;
 150                         }
 151                         ASSERT(i < be32_to_cpu(btp->count));
 152                 }
 153                 p += xfs_dir2_data_entsize(dep->namelen);
 154         }
 155         /*
 156          * Need to have seen all the entries and all the bestfree slots.
 157          */
 158         ASSERT(freeseen == 7);
 159         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
 160                 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
 161                         if (lep[i].address ==
 162                             cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
 163                                 stale++;
 164                         if (i > 0)
 165                                 ASSERT(be32_to_cpu(lep[i].hashval) >= be32_to_cpu(lep[i - 1].hashval));
 166                 }
 167                 ASSERT(count == be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
 168                 ASSERT(stale == be32_to_cpu(btp->stale));
 169         }
 170 }
 171 #endif
 172
 173 /*
 174  * Given a data block and an unused entry from that block,
 175  * return the bestfree entry if any that corresponds to it.
 176  */
 177 STATIC xfs_dir2_data_free_t *
 178 xfs_dir2_data_freefind(
 179         xfs_dir2_data_hdr_t     *hdr,           /* data block */
 180         xfs_dir2_data_unused_t  *dup)           /* data unused entry */
 181 {
 182         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
 183         xfs_dir2_data_aoff_t    off;            /* offset value needed */
 184 #if defined(DEBUG) && defined(__KERNEL__)
 185         int                     matched;        /* matched the value */
 186         int                     seenzero;       /* saw a 0 bestfree entry */
 187 #endif
 188
 189         off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
 190 #if defined(DEBUG) && defined(__KERNEL__)
 191         /*
 192          * Validate some consistency in the bestfree table.
 193          * Check order, non-overlapping entries, and if we find the
 194          * one we're looking for it has to be exact.
 195          */
 196         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 197                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 198         for (dfp = &hdr->bestfree[0], seenzero = matched = 0;
 199              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
 200              dfp++) {
 201                 if (!dfp->offset) {
 202                         ASSERT(!dfp->length);
 203                         seenzero = 1;
 204                         continue;
 205                 }
 206                 ASSERT(seenzero == 0);
 207                 if (be16_to_cpu(dfp->offset) == off) {
 208                         matched = 1;
 209                         ASSERT(dfp->length == dup->length);
 210                 } else if (off < be16_to_cpu(dfp->offset))
 211                         ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
 212                 else
 213                         ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
 214                 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
 215                 if (dfp > &hdr->bestfree[0])
 216                         ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
 217         }
 218 #endif
 219         /*
 220          * If this is smaller than the smallest bestfree entry,
 221          * it can't be there since they're sorted.
 222          */
 223         if (be16_to_cpu(dup->length) <
 224             be16_to_cpu(hdr->bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
 225                 return NULL;
 226         /*
 227          * Look at the three bestfree entries for our guy.
 228          */
 229         for (dfp = &hdr->bestfree[0];
 230              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
 231              dfp++) {
 232                 if (!dfp->offset)
 233                         return NULL;
 234                 if (be16_to_cpu(dfp->offset) == off)
 235                         return dfp;
 236         }
 237         /*
 238          * Didn't find it.  This only happens if there are duplicate lengths.
 239          */
 240         return NULL;
 241 }
 242
 243 /*
 244  * Insert an unused-space entry into the bestfree table.
 245  */
 246 xfs_dir2_data_free_t *                          /* entry inserted */
 247 xfs_dir2_data_freeinsert(
 248         xfs_dir2_data_hdr_t     *hdr,           /* data block pointer */
 249         xfs_dir2_data_unused_t  *dup,           /* unused space */
 250         int                     *loghead)       /* log the data header (out) */
 251 {
 252         xfs_dir2_data_free_t    *dfp;           /* bestfree table pointer */
 253         xfs_dir2_data_free_t    new;            /* new bestfree entry */
 254
 255 #ifdef __KERNEL__
 256         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 257                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 258 #endif
 259         dfp = hdr->bestfree;
 260         new.length = dup->length;
 261         new.offset = cpu_to_be16((char *)dup - (char *)hdr);
 262
 263         /*
 264          * Insert at position 0, 1, or 2; or not at all.
 265          */
 266         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
 267                 dfp[2] = dfp[1];
 268                 dfp[1] = dfp[0];
 269                 dfp[0] = new;
 270                 *loghead = 1;
 271                 return &dfp[0];
 272         }
 273         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
 274                 dfp[2] = dfp[1];
 275                 dfp[1] = new;
 276                 *loghead = 1;
 277                 return &dfp[1];
 278         }
 279         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
 280                 dfp[2] = new;
 281                 *loghead = 1;
 282                 return &dfp[2];
 283         }
 284         return NULL;
 285 }
 286
 287 /*
 288  * Remove a bestfree entry from the table.
 289  */
 290 STATIC void
 291 xfs_dir2_data_freeremove(
 292         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
 293         xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
 294         int                     *loghead)       /* out: log data header */
 295 {
 296 #ifdef __KERNEL__
 297         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 298                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 299 #endif
 300         /*
 301          * It's the first entry, slide the next 2 up.
 302          */
 303         if (dfp == &hdr->bestfree[0]) {
 304                 hdr->bestfree[0] = hdr->bestfree[1];
 305                 hdr->bestfree[1] = hdr->bestfree[2];
 306         }
 307         /*
 308          * It's the second entry, slide the 3rd entry up.
 309          */
 310         else if (dfp == &hdr->bestfree[1])
 311                 hdr->bestfree[1] = hdr->bestfree[2];
 312         /*
 313          * Must be the last entry.
 314          */
 315         else
 316                 ASSERT(dfp == &hdr->bestfree[2]);
 317         /*
 318          * Clear the 3rd entry, must be zero now.
 319          */
 320         hdr->bestfree[2].length = 0;
 321         hdr->bestfree[2].offset = 0;
 322         *loghead = 1;
 323 }
 324
 325 /*
 326  * Given a data block, reconstruct its bestfree map.
 327  */
 328 void
 329 xfs_dir2_data_freescan(
 330         xfs_mount_t             *mp,            /* filesystem mount point */
 331         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
 332         int                     *loghead)       /* out: log data header */
 333 {
 334         xfs_dir2_block_tail_t   *btp;           /* block tail */
 335         xfs_dir2_data_entry_t   *dep;           /* active data entry */
 336         xfs_dir2_data_unused_t  *dup;           /* unused data entry */
 337         char                    *endp;          /* end of block's data */
 338         char                    *p;             /* current entry pointer */
 339
 340 #ifdef __KERNEL__
 341         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 342                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 343 #endif
 344         /*
 345          * Start by clearing the table.
 346          */
 347         memset(hdr->bestfree, 0, sizeof(hdr->bestfree));
 348         *loghead = 1;
 349         /*
 350          * Set up pointers.
 351          */
 352         p = (char *)(hdr + 1);
 353         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
 354                 btp = xfs_dir2_block_tail_p(mp, hdr);
 355                 endp = (char *)xfs_dir2_block_leaf_p(btp);
 356         } else
 357                 endp = (char *)hdr + mp->m_dirblksize;
 358         /*
 359          * Loop over the block's entries.
 360          */
 361         while (p < endp) {
 362                 dup = (xfs_dir2_data_unused_t *)p;
 363                 /*
 364                  * If it's a free entry, insert it.
 365                  */
 366                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 367                         ASSERT((char *)dup - (char *)hdr ==
 368                                be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 369                         xfs_dir2_data_freeinsert(hdr, dup, loghead);
 370                         p += be16_to_cpu(dup->length);
 371                 }
 372                 /*
 373                  * For active entries, check their tags and skip them.
 374                  */
 375                 else {
 376                         dep = (xfs_dir2_data_entry_t *)p;
 377                         ASSERT((char *)dep - (char *)hdr ==
 378                                be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
 379                         p += xfs_dir2_data_entsize(dep->namelen);
 380                 }
 381         }
 382 }
 383
 384 /*
 385  * Initialize a data block at the given block number in the directory.
 386  * Give back the buffer for the created block.
 387  */
 388 int                                             /* error */
 389 xfs_dir2_data_init(
 390         xfs_da_args_t           *args,          /* directory operation args */
 391         xfs_dir2_db_t           blkno,          /* logical dir block number */
 392         struct xfs_buf          **bpp)          /* output block buffer */
 393 {
 394         struct xfs_buf          *bp;            /* block buffer */
 395         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
 396         xfs_inode_t             *dp;            /* incore directory inode */
 397         xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
 398         int                     error;          /* error return value */
 399         int                     i;              /* bestfree index */
 400         xfs_mount_t             *mp;            /* filesystem mount point */
 401         xfs_trans_t             *tp;            /* transaction pointer */
 402         int                     t;              /* temp */
 403
 404         dp = args->dp;
 405         mp = dp->i_mount;
 406         tp = args->trans;
 407         /*
 408          * Get the buffer set up for the block.
 409          */
 410         error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
 411                 XFS_DATA_FORK);
 412         if (error) {
 413                 return error;
 414         }
 415         ASSERT(bp != NULL);
 416
 417         /*
 418          * Initialize the header.
 419          */
 420         hdr = bp->b_addr;
 421         hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
 422         hdr->bestfree[0].offset = cpu_to_be16(sizeof(*hdr));
 423         for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
 424                 hdr->bestfree[i].length = 0;
 425                 hdr->bestfree[i].offset = 0;
 426         }
 427
 428         /*
 429          * Set up an unused entry for the block's body.
 430          */
 431         dup = (xfs_dir2_data_unused_t *)(hdr + 1);
 432         dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 433
 434         t = mp->m_dirblksize - (uint)sizeof(*hdr);
 435         hdr->bestfree[0].length = cpu_to_be16(t);
 436         dup->length = cpu_to_be16(t);
 437         *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)hdr);
 438         /*
 439          * Log it and return it.
 440          */
 441         xfs_dir2_data_log_header(tp, bp);
 442         xfs_dir2_data_log_unused(tp, bp, dup);
 443         *bpp = bp;
 444         return 0;
 445 }
 446
 447 /*
 448  * Log an active data entry from the block.
 449  */
 450 void
 451 xfs_dir2_data_log_entry(
 452         struct xfs_trans        *tp,
 453         struct xfs_buf          *bp,
 454         xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
 455 {
 456         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 457
 458         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 459                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 460
 461         xfs_trans_log_buf(tp, bp, (uint)((char *)dep - (char *)hdr),
 462                 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
 463                        (char *)hdr - 1));
 464 }
 465
 466 /*
 467  * Log a data block header.
 468  */
 469 void
 470 xfs_dir2_data_log_header(
 471         struct xfs_trans        *tp,
 472         struct xfs_buf          *bp)
 473 {
 474         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 475
 476         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 477                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 478
 479         xfs_trans_log_buf(tp, bp, 0, sizeof(*hdr) - 1);
 480 }
 481
 482 /*
 483  * Log a data unused entry.
 484  */
 485 void
 486 xfs_dir2_data_log_unused(
 487         struct xfs_trans        *tp,
 488         struct xfs_buf          *bp,
 489         xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
 490 {
 491         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 492
 493         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 494                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 495
 496         /*
 497          * Log the first part of the unused entry.
 498          */
 499         xfs_trans_log_buf(tp, bp, (uint)((char *)dup - (char *)hdr),
 500                 (uint)((char *)&dup->length + sizeof(dup->length) -
 501                        1 - (char *)hdr));
 502         /*
 503          * Log the end (tag) of the unused entry.
 504          */
 505         xfs_trans_log_buf(tp, bp,
 506                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr),
 507                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr +
 508                        sizeof(xfs_dir2_data_off_t) - 1));
 509 }
 510
 511 /*
 512  * Make a byte range in the data block unused.
 513  * Its current contents are unimportant.
 514  */
 515 void
 516 xfs_dir2_data_make_free(
 517         struct xfs_trans        *tp,
 518         struct xfs_buf          *bp,
 519         xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
 520         xfs_dir2_data_aoff_t    len,            /* length in bytes */
 521         int                     *needlogp,      /* out: log header */
 522         int                     *needscanp)     /* out: regen bestfree */
 523 {
 524         xfs_dir2_data_hdr_t     *hdr;           /* data block pointer */
 525         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 526         char                    *endptr;        /* end of data area */
 527         xfs_mount_t             *mp;            /* filesystem mount point */
 528         int                     needscan;       /* need to regen bestfree */
 529         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 530         xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
 531         xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
 532
 533         mp = tp->t_mountp;
 534         hdr = bp->b_addr;
 535
 536         /*
 537          * Figure out where the end of the data area is.
 538          */
 539         if (hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC))
 540                 endptr = (char *)hdr + mp->m_dirblksize;
 541         else {
 542                 xfs_dir2_block_tail_t   *btp;   /* block tail */
 543
 544                 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 545                 btp = xfs_dir2_block_tail_p(mp, hdr);
 546                 endptr = (char *)xfs_dir2_block_leaf_p(btp);
 547         }
 548         /*
 549          * If this isn't the start of the block, then back up to
 550          * the previous entry and see if it's free.
 551          */
 552         if (offset > sizeof(*hdr)) {
 553                 __be16                  *tagp;  /* tag just before us */
 554
 555                 tagp = (__be16 *)((char *)hdr + offset) - 1;
 556                 prevdup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
 557                 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 558                         prevdup = NULL;
 559         } else
 560                 prevdup = NULL;
 561         /*
 562          * If this isn't the end of the block, see if the entry after
 563          * us is free.
 564          */
 565         if ((char *)hdr + offset + len < endptr) {
 566                 postdup =
 567                         (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 568                 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 569                         postdup = NULL;
 570         } else
 571                 postdup = NULL;
 572         ASSERT(*needscanp == 0);
 573         needscan = 0;
 574         /*
 575          * Previous and following entries are both free,
 576          * merge everything into a single free entry.
 577          */
 578         if (prevdup && postdup) {
 579                 xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
 580
 581                 /*
 582                  * See if prevdup and/or postdup are in bestfree table.
 583                  */
 584                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
 585                 dfp2 = xfs_dir2_data_freefind(hdr, postdup);
 586                 /*
 587                  * We need a rescan unless there are exactly 2 free entries
 588                  * namely our two.  Then we know what's happening, otherwise
 589                  * since the third bestfree is there, there might be more
 590                  * entries.
 591                  */
 592                 needscan = (hdr->bestfree[2].length != 0);
 593                 /*
 594                  * Fix up the new big freespace.
 595                  */
 596                 be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
 597                 *xfs_dir2_data_unused_tag_p(prevdup) =
 598                         cpu_to_be16((char *)prevdup - (char *)hdr);
 599                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 600                 if (!needscan) {
 601                         /*
 602                          * Has to be the case that entries 0 and 1 are
 603                          * dfp and dfp2 (don't know which is which), and
 604                          * entry 2 is empty.
 605                          * Remove entry 1 first then entry 0.
 606                          */
 607                         ASSERT(dfp && dfp2);
 608                         if (dfp == &hdr->bestfree[1]) {
 609                                 dfp = &hdr->bestfree[0];
 610                                 ASSERT(dfp2 == dfp);
 611                                 dfp2 = &hdr->bestfree[1];
 612                         }
 613                         xfs_dir2_data_freeremove(hdr, dfp2, needlogp);
 614                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 615                         /*
 616                          * Now insert the new entry.
 617                          */
 618                         dfp = xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
 619                         ASSERT(dfp == &hdr->bestfree[0]);
 620                         ASSERT(dfp->length == prevdup->length);
 621                         ASSERT(!dfp[1].length);
 622                         ASSERT(!dfp[2].length);
 623                 }
 624         }
 625         /*
 626          * The entry before us is free, merge with it.
 627          */
 628         else if (prevdup) {
 629                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
 630                 be16_add_cpu(&prevdup->length, len);
 631                 *xfs_dir2_data_unused_tag_p(prevdup) =
 632                         cpu_to_be16((char *)prevdup - (char *)hdr);
 633                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 634                 /*
 635                  * If the previous entry was in the table, the new entry
 636                  * is longer, so it will be in the table too.  Remove
 637                  * the old one and add the new one.
 638                  */
 639                 if (dfp) {
 640                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 641                         xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
 642                 }
 643                 /*
 644                  * Otherwise we need a scan if the new entry is big enough.
 645                  */
 646                 else {
 647                         needscan = be16_to_cpu(prevdup->length) >
 648                                    be16_to_cpu(hdr->bestfree[2].length);
 649                 }
 650         }
 651         /*
 652          * The following entry is free, merge with it.
 653          */
 654         else if (postdup) {
 655                 dfp = xfs_dir2_data_freefind(hdr, postdup);
 656                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
 657                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 658                 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
 659                 *xfs_dir2_data_unused_tag_p(newdup) =
 660                         cpu_to_be16((char *)newdup - (char *)hdr);
 661                 xfs_dir2_data_log_unused(tp, bp, newdup);
 662                 /*
 663                  * If the following entry was in the table, the new entry
 664                  * is longer, so it will be in the table too.  Remove
 665                  * the old one and add the new one.
 666                  */
 667                 if (dfp) {
 668                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 669                         xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 670                 }
 671                 /*
 672                  * Otherwise we need a scan if the new entry is big enough.
 673                  */
 674                 else {
 675                         needscan = be16_to_cpu(newdup->length) >
 676                                    be16_to_cpu(hdr->bestfree[2].length);
 677                 }
 678         }
 679         /*
 680          * Neither neighbor is free.  Make a new entry.
 681          */
 682         else {
 683                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
 684                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 685                 newdup->length = cpu_to_be16(len);
 686                 *xfs_dir2_data_unused_tag_p(newdup) =
 687                         cpu_to_be16((char *)newdup - (char *)hdr);
 688                 xfs_dir2_data_log_unused(tp, bp, newdup);
 689                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 690         }
 691         *needscanp = needscan;
 692 }
 693
 694 /*
 695  * Take a byte range out of an existing unused space and make it un-free.
 696  */
 697 void
 698 xfs_dir2_data_use_free(
 699         struct xfs_trans        *tp,
 700         struct xfs_buf          *bp,
 701         xfs_dir2_data_unused_t  *dup,           /* unused entry */
 702         xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
 703         xfs_dir2_data_aoff_t    len,            /* length to use */
 704         int                     *needlogp,      /* out: need to log header */
 705         int                     *needscanp)     /* out: need regen bestfree */
 706 {
 707         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
 708         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 709         int                     matchback;      /* matches end of freespace */
 710         int                     matchfront;     /* matches start of freespace */
 711         int                     needscan;       /* need to regen bestfree */
 712         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 713         xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
 714         int                     oldlen;         /* old unused entry's length */
 715
 716         hdr = bp->b_addr;
 717         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 718                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 719         ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
 720         ASSERT(offset >= (char *)dup - (char *)hdr);
 721         ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)hdr);
 722         ASSERT((char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 723         /*
 724          * Look up the entry in the bestfree table.
 725          */
 726         dfp = xfs_dir2_data_freefind(hdr, dup);
 727         oldlen = be16_to_cpu(dup->length);
 728         ASSERT(dfp || oldlen <= be16_to_cpu(hdr->bestfree[2].length));
 729         /*
 730          * Check for alignment with front and back of the entry.
 731          */
 732         matchfront = (char *)dup - (char *)hdr == offset;
 733         matchback = (char *)dup + oldlen - (char *)hdr == offset + len;
 734         ASSERT(*needscanp == 0);
 735         needscan = 0;
 736         /*
 737          * If we matched it exactly we just need to get rid of it from
 738          * the bestfree table.
 739          */
 740         if (matchfront && matchback) {
 741                 if (dfp) {
 742                         needscan = (hdr->bestfree[2].offset != 0);
 743                         if (!needscan)
 744                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 745                 }
 746         }
 747         /*
 748          * We match the first part of the entry.
 749          * Make a new entry with the remaining freespace.
 750          */
 751         else if (matchfront) {
 752                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 753                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 754                 newdup->length = cpu_to_be16(oldlen - len);
 755                 *xfs_dir2_data_unused_tag_p(newdup) =
 756                         cpu_to_be16((char *)newdup - (char *)hdr);
 757                 xfs_dir2_data_log_unused(tp, bp, newdup);
 758                 /*
 759                  * If it was in the table, remove it and add the new one.
 760                  */
 761                 if (dfp) {
 762                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 763                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 764                         ASSERT(dfp != NULL);
 765                         ASSERT(dfp->length == newdup->length);
 766                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
 767                         /*
 768                          * If we got inserted at the last slot,
 769                          * that means we don't know if there was a better
 770                          * choice for the last slot, or not.  Rescan.
 771                          */
 772                         needscan = dfp == &hdr->bestfree[2];
 773                 }
 774         }
 775         /*
 776          * We match the last part of the entry.
 777          * Trim the allocated space off the tail of the entry.
 778          */
 779         else if (matchback) {
 780                 newdup = dup;
 781                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
 782                 *xfs_dir2_data_unused_tag_p(newdup) =
 783                         cpu_to_be16((char *)newdup - (char *)hdr);
 784                 xfs_dir2_data_log_unused(tp, bp, newdup);
 785                 /*
 786                  * If it was in the table, remove it and add the new one.
 787                  */
 788                 if (dfp) {
 789                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 790                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 791                         ASSERT(dfp != NULL);
 792                         ASSERT(dfp->length == newdup->length);
 793                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
 794                         /*
 795                          * If we got inserted at the last slot,
 796                          * that means we don't know if there was a better
 797                          * choice for the last slot, or not.  Rescan.
 798                          */
 799                         needscan = dfp == &hdr->bestfree[2];
 800                 }
 801         }
 802         /*
 803          * Poking out the middle of an entry.
 804          * Make two new entries.
 805          */
 806         else {
 807                 newdup = dup;
 808                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
 809                 *xfs_dir2_data_unused_tag_p(newdup) =
 810                         cpu_to_be16((char *)newdup - (char *)hdr);
 811                 xfs_dir2_data_log_unused(tp, bp, newdup);
 812                 newdup2 = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 813                 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 814                 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
 815                 *xfs_dir2_data_unused_tag_p(newdup2) =
 816                         cpu_to_be16((char *)newdup2 - (char *)hdr);
 817                 xfs_dir2_data_log_unused(tp, bp, newdup2);
 818                 /*
 819                  * If the old entry was in the table, we need to scan
 820                  * if the 3rd entry was valid, since these entries
 821                  * are smaller than the old one.
 822                  * If we don't need to scan that means there were 1 or 2
 823                  * entries in the table, and removing the old and adding
 824                  * the 2 new will work.
 825                  */
 826                 if (dfp) {
 827                         needscan = (hdr->bestfree[2].length != 0);
 828                         if (!needscan) {
 829                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 830                                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 831                                 xfs_dir2_data_freeinsert(hdr, newdup2,
 832                                                          needlogp);
 833                         }
 834                 }
 835         }
 836         *needscanp = needscan;
 837 }