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 /*
  38  * Check the consistency of the data block.
  39  * The input can also be a block-format directory.
  40  * Return 0 is the buffer is good, otherwise an error.
  41  */
  42 int
  43 __xfs_dir2_data_check(
  44         struct xfs_inode        *dp,            /* incore inode pointer */
  45         struct xfs_buf          *bp)            /* data block's buffer */
  46 {
  47         xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
  48         xfs_dir2_data_free_t    *bf;            /* bestfree table */
  49         xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
  50         int                     count;          /* count of entries found */
  51         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
  52         xfs_dir2_data_entry_t   *dep;           /* data entry */
  53         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
  54         xfs_dir2_data_unused_t  *dup;           /* unused entry */
  55         char                    *endp;          /* end of useful data */
  56         int                     freeseen;       /* mask of bestfrees seen */
  57         xfs_dahash_t            hash;           /* hash of current name */
  58         int                     i;              /* leaf index */
  59         int                     lastfree;       /* last entry was unused */
  60         xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
  61         xfs_mount_t             *mp;            /* filesystem mount point */
  62         char                    *p;             /* current data position */
  63         int                     stale;          /* count of stale leaves */
  64         struct xfs_name         name;
  65
  66         mp = bp->b_target->bt_mount;
  67         hdr = bp->b_addr;
  68         bf = hdr->bestfree;
  69         p = (char *)(hdr + 1);
  70
  71         switch (hdr->magic) {
  72         case 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                 break;
  77         case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
  78                 endp = (char *)hdr + mp->m_dirblksize;
  79                 break;
  80         default:
  81                 XFS_ERROR_REPORT("Bad Magic", XFS_ERRLEVEL_LOW, mp);
  82                 return EFSCORRUPTED;
  83         }
  84
  85         count = lastfree = freeseen = 0;
  86         /*
  87          * Account for zero bestfree entries.
  88          */
  89         if (!bf[0].length) {
  90                 XFS_WANT_CORRUPTED_RETURN(!bf[0].offset);
  91                 freeseen |= 1 << 0;
  92         }
  93         if (!bf[1].length) {
  94                 XFS_WANT_CORRUPTED_RETURN(!bf[1].offset);
  95                 freeseen |= 1 << 1;
  96         }
  97         if (!bf[2].length) {
  98                 XFS_WANT_CORRUPTED_RETURN(!bf[2].offset);
  99                 freeseen |= 1 << 2;
 100         }
 101
 102         XFS_WANT_CORRUPTED_RETURN(be16_to_cpu(bf[0].length) >=
 103                                                 be16_to_cpu(bf[1].length));
 104         XFS_WANT_CORRUPTED_RETURN(be16_to_cpu(bf[1].length) >=
 105                                                 be16_to_cpu(bf[2].length));
 106         /*
 107          * Loop over the data/unused entries.
 108          */
 109         while (p < endp) {
 110                 dup = (xfs_dir2_data_unused_t *)p;
 111                 /*
 112                  * If it's unused, look for the space in the bestfree table.
 113                  * If we find it, account for that, else make sure it
 114                  * doesn't need to be there.
 115                  */
 116                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 117                         XFS_WANT_CORRUPTED_RETURN(lastfree == 0);
 118                         XFS_WANT_CORRUPTED_RETURN(
 119                                 be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
 120                                                (char *)dup - (char *)hdr);
 121                         dfp = xfs_dir2_data_freefind(hdr, dup);
 122                         if (dfp) {
 123                                 i = (int)(dfp - bf);
 124                                 XFS_WANT_CORRUPTED_RETURN(
 125                                         (freeseen & (1 << i)) == 0);
 126                                 freeseen |= 1 << i;
 127                         } else {
 128                                 XFS_WANT_CORRUPTED_RETURN(
 129                                         be16_to_cpu(dup->length) <=
 130                                                 be16_to_cpu(bf[2].length));
 131                         }
 132                         p += be16_to_cpu(dup->length);
 133                         lastfree = 1;
 134                         continue;
 135                 }
 136                 /*
 137                  * It's a real entry.  Validate the fields.
 138                  * If this is a block directory then make sure it's
 139                  * in the leaf section of the block.
 140                  * The linear search is crude but this is DEBUG code.
 141                  */
 142                 dep = (xfs_dir2_data_entry_t *)p;
 143                 XFS_WANT_CORRUPTED_RETURN(dep->namelen != 0);
 144                 XFS_WANT_CORRUPTED_RETURN(
 145                         !xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)));
 146                 XFS_WANT_CORRUPTED_RETURN(
 147                         be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
 148                                                (char *)dep - (char *)hdr);
 149                 count++;
 150                 lastfree = 0;
 151                 if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
 152                         addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
 153                                 (xfs_dir2_data_aoff_t)
 154                                 ((char *)dep - (char *)hdr));
 155                         name.name = dep->name;
 156                         name.len = dep->namelen;
 157                         hash = mp->m_dirnameops->hashname(&name);
 158                         for (i = 0; i < be32_to_cpu(btp->count); i++) {
 159                                 if (be32_to_cpu(lep[i].address) == addr &&
 160                                     be32_to_cpu(lep[i].hashval) == hash)
 161                                         break;
 162                         }
 163                         XFS_WANT_CORRUPTED_RETURN(i < be32_to_cpu(btp->count));
 164                 }
 165                 p += xfs_dir2_data_entsize(dep->namelen);
 166         }
 167         /*
 168          * Need to have seen all the entries and all the bestfree slots.
 169          */
 170         XFS_WANT_CORRUPTED_RETURN(freeseen == 7);
 171         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
 172                 for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
 173                         if (lep[i].address ==
 174                             cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
 175                                 stale++;
 176                         if (i > 0)
 177                                 XFS_WANT_CORRUPTED_RETURN(
 178                                         be32_to_cpu(lep[i].hashval) >=
 179                                                 be32_to_cpu(lep[i - 1].hashval));
 180                 }
 181                 XFS_WANT_CORRUPTED_RETURN(count ==
 182                         be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
 183                 XFS_WANT_CORRUPTED_RETURN(stale == be32_to_cpu(btp->stale));
 184         }
 185         return 0;
 186 }
 187
 188 /*
 189  * Given a data block and an unused entry from that block,
 190  * return the bestfree entry if any that corresponds to it.
 191  */
 192 STATIC xfs_dir2_data_free_t *
 193 xfs_dir2_data_freefind(
 194         xfs_dir2_data_hdr_t     *hdr,           /* data block */
 195         xfs_dir2_data_unused_t  *dup)           /* data unused entry */
 196 {
 197         xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
 198         xfs_dir2_data_aoff_t    off;            /* offset value needed */
 199 #if defined(DEBUG) && defined(__KERNEL__)
 200         int                     matched;        /* matched the value */
 201         int                     seenzero;       /* saw a 0 bestfree entry */
 202 #endif
 203
 204         off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
 205 #if defined(DEBUG) && defined(__KERNEL__)
 206         /*
 207          * Validate some consistency in the bestfree table.
 208          * Check order, non-overlapping entries, and if we find the
 209          * one we're looking for it has to be exact.
 210          */
 211         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 212                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 213         for (dfp = &hdr->bestfree[0], seenzero = matched = 0;
 214              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
 215              dfp++) {
 216                 if (!dfp->offset) {
 217                         ASSERT(!dfp->length);
 218                         seenzero = 1;
 219                         continue;
 220                 }
 221                 ASSERT(seenzero == 0);
 222                 if (be16_to_cpu(dfp->offset) == off) {
 223                         matched = 1;
 224                         ASSERT(dfp->length == dup->length);
 225                 } else if (off < be16_to_cpu(dfp->offset))
 226                         ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
 227                 else
 228                         ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
 229                 ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
 230                 if (dfp > &hdr->bestfree[0])
 231                         ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
 232         }
 233 #endif
 234         /*
 235          * If this is smaller than the smallest bestfree entry,
 236          * it can't be there since they're sorted.
 237          */
 238         if (be16_to_cpu(dup->length) <
 239             be16_to_cpu(hdr->bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
 240                 return NULL;
 241         /*
 242          * Look at the three bestfree entries for our guy.
 243          */
 244         for (dfp = &hdr->bestfree[0];
 245              dfp < &hdr->bestfree[XFS_DIR2_DATA_FD_COUNT];
 246              dfp++) {
 247                 if (!dfp->offset)
 248                         return NULL;
 249                 if (be16_to_cpu(dfp->offset) == off)
 250                         return dfp;
 251         }
 252         /*
 253          * Didn't find it.  This only happens if there are duplicate lengths.
 254          */
 255         return NULL;
 256 }
 257
 258 /*
 259  * Insert an unused-space entry into the bestfree table.
 260  */
 261 xfs_dir2_data_free_t *                          /* entry inserted */
 262 xfs_dir2_data_freeinsert(
 263         xfs_dir2_data_hdr_t     *hdr,           /* data block pointer */
 264         xfs_dir2_data_unused_t  *dup,           /* unused space */
 265         int                     *loghead)       /* log the data header (out) */
 266 {
 267         xfs_dir2_data_free_t    *dfp;           /* bestfree table pointer */
 268         xfs_dir2_data_free_t    new;            /* new bestfree entry */
 269
 270 #ifdef __KERNEL__
 271         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 272                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 273 #endif
 274         dfp = hdr->bestfree;
 275         new.length = dup->length;
 276         new.offset = cpu_to_be16((char *)dup - (char *)hdr);
 277
 278         /*
 279          * Insert at position 0, 1, or 2; or not at all.
 280          */
 281         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
 282                 dfp[2] = dfp[1];
 283                 dfp[1] = dfp[0];
 284                 dfp[0] = new;
 285                 *loghead = 1;
 286                 return &dfp[0];
 287         }
 288         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
 289                 dfp[2] = dfp[1];
 290                 dfp[1] = new;
 291                 *loghead = 1;
 292                 return &dfp[1];
 293         }
 294         if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
 295                 dfp[2] = new;
 296                 *loghead = 1;
 297                 return &dfp[2];
 298         }
 299         return NULL;
 300 }
 301
 302 /*
 303  * Remove a bestfree entry from the table.
 304  */
 305 STATIC void
 306 xfs_dir2_data_freeremove(
 307         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
 308         xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
 309         int                     *loghead)       /* out: log data header */
 310 {
 311 #ifdef __KERNEL__
 312         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 313                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 314 #endif
 315         /*
 316          * It's the first entry, slide the next 2 up.
 317          */
 318         if (dfp == &hdr->bestfree[0]) {
 319                 hdr->bestfree[0] = hdr->bestfree[1];
 320                 hdr->bestfree[1] = hdr->bestfree[2];
 321         }
 322         /*
 323          * It's the second entry, slide the 3rd entry up.
 324          */
 325         else if (dfp == &hdr->bestfree[1])
 326                 hdr->bestfree[1] = hdr->bestfree[2];
 327         /*
 328          * Must be the last entry.
 329          */
 330         else
 331                 ASSERT(dfp == &hdr->bestfree[2]);
 332         /*
 333          * Clear the 3rd entry, must be zero now.
 334          */
 335         hdr->bestfree[2].length = 0;
 336         hdr->bestfree[2].offset = 0;
 337         *loghead = 1;
 338 }
 339
 340 /*
 341  * Given a data block, reconstruct its bestfree map.
 342  */
 343 void
 344 xfs_dir2_data_freescan(
 345         xfs_mount_t             *mp,            /* filesystem mount point */
 346         xfs_dir2_data_hdr_t     *hdr,           /* data block header */
 347         int                     *loghead)       /* out: log data header */
 348 {
 349         xfs_dir2_block_tail_t   *btp;           /* block tail */
 350         xfs_dir2_data_entry_t   *dep;           /* active data entry */
 351         xfs_dir2_data_unused_t  *dup;           /* unused data entry */
 352         char                    *endp;          /* end of block's data */
 353         char                    *p;             /* current entry pointer */
 354
 355 #ifdef __KERNEL__
 356         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 357                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 358 #endif
 359         /*
 360          * Start by clearing the table.
 361          */
 362         memset(hdr->bestfree, 0, sizeof(hdr->bestfree));
 363         *loghead = 1;
 364         /*
 365          * Set up pointers.
 366          */
 367         p = (char *)(hdr + 1);
 368         if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC)) {
 369                 btp = xfs_dir2_block_tail_p(mp, hdr);
 370                 endp = (char *)xfs_dir2_block_leaf_p(btp);
 371         } else
 372                 endp = (char *)hdr + mp->m_dirblksize;
 373         /*
 374          * Loop over the block's entries.
 375          */
 376         while (p < endp) {
 377                 dup = (xfs_dir2_data_unused_t *)p;
 378                 /*
 379                  * If it's a free entry, insert it.
 380                  */
 381                 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 382                         ASSERT((char *)dup - (char *)hdr ==
 383                                be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 384                         xfs_dir2_data_freeinsert(hdr, dup, loghead);
 385                         p += be16_to_cpu(dup->length);
 386                 }
 387                 /*
 388                  * For active entries, check their tags and skip them.
 389                  */
 390                 else {
 391                         dep = (xfs_dir2_data_entry_t *)p;
 392                         ASSERT((char *)dep - (char *)hdr ==
 393                                be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
 394                         p += xfs_dir2_data_entsize(dep->namelen);
 395                 }
 396         }
 397 }
 398
 399 /*
 400  * Initialize a data block at the given block number in the directory.
 401  * Give back the buffer for the created block.
 402  */
 403 int                                             /* error */
 404 xfs_dir2_data_init(
 405         xfs_da_args_t           *args,          /* directory operation args */
 406         xfs_dir2_db_t           blkno,          /* logical dir block number */
 407         struct xfs_buf          **bpp)          /* output block buffer */
 408 {
 409         struct xfs_buf          *bp;            /* block buffer */
 410         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
 411         xfs_inode_t             *dp;            /* incore directory inode */
 412         xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
 413         int                     error;          /* error return value */
 414         int                     i;              /* bestfree index */
 415         xfs_mount_t             *mp;            /* filesystem mount point */
 416         xfs_trans_t             *tp;            /* transaction pointer */
 417         int                     t;              /* temp */
 418
 419         dp = args->dp;
 420         mp = dp->i_mount;
 421         tp = args->trans;
 422         /*
 423          * Get the buffer set up for the block.
 424          */
 425         error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
 426                 XFS_DATA_FORK);
 427         if (error) {
 428                 return error;
 429         }
 430         ASSERT(bp != NULL);
 431
 432         /*
 433          * Initialize the header.
 434          */
 435         hdr = bp->b_addr;
 436         hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
 437         hdr->bestfree[0].offset = cpu_to_be16(sizeof(*hdr));
 438         for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
 439                 hdr->bestfree[i].length = 0;
 440                 hdr->bestfree[i].offset = 0;
 441         }
 442
 443         /*
 444          * Set up an unused entry for the block's body.
 445          */
 446         dup = (xfs_dir2_data_unused_t *)(hdr + 1);
 447         dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 448
 449         t = mp->m_dirblksize - (uint)sizeof(*hdr);
 450         hdr->bestfree[0].length = cpu_to_be16(t);
 451         dup->length = cpu_to_be16(t);
 452         *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)hdr);
 453         /*
 454          * Log it and return it.
 455          */
 456         xfs_dir2_data_log_header(tp, bp);
 457         xfs_dir2_data_log_unused(tp, bp, dup);
 458         *bpp = bp;
 459         return 0;
 460 }
 461
 462 /*
 463  * Log an active data entry from the block.
 464  */
 465 void
 466 xfs_dir2_data_log_entry(
 467         struct xfs_trans        *tp,
 468         struct xfs_buf          *bp,
 469         xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
 470 {
 471         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 472
 473         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 474                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 475
 476         xfs_trans_log_buf(tp, bp, (uint)((char *)dep - (char *)hdr),
 477                 (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
 478                        (char *)hdr - 1));
 479 }
 480
 481 /*
 482  * Log a data block header.
 483  */
 484 void
 485 xfs_dir2_data_log_header(
 486         struct xfs_trans        *tp,
 487         struct xfs_buf          *bp)
 488 {
 489         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 490
 491         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 492                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 493
 494         xfs_trans_log_buf(tp, bp, 0, sizeof(*hdr) - 1);
 495 }
 496
 497 /*
 498  * Log a data unused entry.
 499  */
 500 void
 501 xfs_dir2_data_log_unused(
 502         struct xfs_trans        *tp,
 503         struct xfs_buf          *bp,
 504         xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
 505 {
 506         xfs_dir2_data_hdr_t     *hdr = bp->b_addr;
 507
 508         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 509                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 510
 511         /*
 512          * Log the first part of the unused entry.
 513          */
 514         xfs_trans_log_buf(tp, bp, (uint)((char *)dup - (char *)hdr),
 515                 (uint)((char *)&dup->length + sizeof(dup->length) -
 516                        1 - (char *)hdr));
 517         /*
 518          * Log the end (tag) of the unused entry.
 519          */
 520         xfs_trans_log_buf(tp, bp,
 521                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr),
 522                 (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr +
 523                        sizeof(xfs_dir2_data_off_t) - 1));
 524 }
 525
 526 /*
 527  * Make a byte range in the data block unused.
 528  * Its current contents are unimportant.
 529  */
 530 void
 531 xfs_dir2_data_make_free(
 532         struct xfs_trans        *tp,
 533         struct xfs_buf          *bp,
 534         xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
 535         xfs_dir2_data_aoff_t    len,            /* length in bytes */
 536         int                     *needlogp,      /* out: log header */
 537         int                     *needscanp)     /* out: regen bestfree */
 538 {
 539         xfs_dir2_data_hdr_t     *hdr;           /* data block pointer */
 540         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 541         char                    *endptr;        /* end of data area */
 542         xfs_mount_t             *mp;            /* filesystem mount point */
 543         int                     needscan;       /* need to regen bestfree */
 544         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 545         xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
 546         xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
 547
 548         mp = tp->t_mountp;
 549         hdr = bp->b_addr;
 550
 551         /*
 552          * Figure out where the end of the data area is.
 553          */
 554         if (hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC))
 555                 endptr = (char *)hdr + mp->m_dirblksize;
 556         else {
 557                 xfs_dir2_block_tail_t   *btp;   /* block tail */
 558
 559                 ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 560                 btp = xfs_dir2_block_tail_p(mp, hdr);
 561                 endptr = (char *)xfs_dir2_block_leaf_p(btp);
 562         }
 563         /*
 564          * If this isn't the start of the block, then back up to
 565          * the previous entry and see if it's free.
 566          */
 567         if (offset > sizeof(*hdr)) {
 568                 __be16                  *tagp;  /* tag just before us */
 569
 570                 tagp = (__be16 *)((char *)hdr + offset) - 1;
 571                 prevdup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
 572                 if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 573                         prevdup = NULL;
 574         } else
 575                 prevdup = NULL;
 576         /*
 577          * If this isn't the end of the block, see if the entry after
 578          * us is free.
 579          */
 580         if ((char *)hdr + offset + len < endptr) {
 581                 postdup =
 582                         (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 583                 if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 584                         postdup = NULL;
 585         } else
 586                 postdup = NULL;
 587         ASSERT(*needscanp == 0);
 588         needscan = 0;
 589         /*
 590          * Previous and following entries are both free,
 591          * merge everything into a single free entry.
 592          */
 593         if (prevdup && postdup) {
 594                 xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
 595
 596                 /*
 597                  * See if prevdup and/or postdup are in bestfree table.
 598                  */
 599                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
 600                 dfp2 = xfs_dir2_data_freefind(hdr, postdup);
 601                 /*
 602                  * We need a rescan unless there are exactly 2 free entries
 603                  * namely our two.  Then we know what's happening, otherwise
 604                  * since the third bestfree is there, there might be more
 605                  * entries.
 606                  */
 607                 needscan = (hdr->bestfree[2].length != 0);
 608                 /*
 609                  * Fix up the new big freespace.
 610                  */
 611                 be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
 612                 *xfs_dir2_data_unused_tag_p(prevdup) =
 613                         cpu_to_be16((char *)prevdup - (char *)hdr);
 614                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 615                 if (!needscan) {
 616                         /*
 617                          * Has to be the case that entries 0 and 1 are
 618                          * dfp and dfp2 (don't know which is which), and
 619                          * entry 2 is empty.
 620                          * Remove entry 1 first then entry 0.
 621                          */
 622                         ASSERT(dfp && dfp2);
 623                         if (dfp == &hdr->bestfree[1]) {
 624                                 dfp = &hdr->bestfree[0];
 625                                 ASSERT(dfp2 == dfp);
 626                                 dfp2 = &hdr->bestfree[1];
 627                         }
 628                         xfs_dir2_data_freeremove(hdr, dfp2, needlogp);
 629                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 630                         /*
 631                          * Now insert the new entry.
 632                          */
 633                         dfp = xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
 634                         ASSERT(dfp == &hdr->bestfree[0]);
 635                         ASSERT(dfp->length == prevdup->length);
 636                         ASSERT(!dfp[1].length);
 637                         ASSERT(!dfp[2].length);
 638                 }
 639         }
 640         /*
 641          * The entry before us is free, merge with it.
 642          */
 643         else if (prevdup) {
 644                 dfp = xfs_dir2_data_freefind(hdr, prevdup);
 645                 be16_add_cpu(&prevdup->length, len);
 646                 *xfs_dir2_data_unused_tag_p(prevdup) =
 647                         cpu_to_be16((char *)prevdup - (char *)hdr);
 648                 xfs_dir2_data_log_unused(tp, bp, prevdup);
 649                 /*
 650                  * If the previous entry was in the table, the new entry
 651                  * is longer, so it will be in the table too.  Remove
 652                  * the old one and add the new one.
 653                  */
 654                 if (dfp) {
 655                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 656                         xfs_dir2_data_freeinsert(hdr, prevdup, needlogp);
 657                 }
 658                 /*
 659                  * Otherwise we need a scan if the new entry is big enough.
 660                  */
 661                 else {
 662                         needscan = be16_to_cpu(prevdup->length) >
 663                                    be16_to_cpu(hdr->bestfree[2].length);
 664                 }
 665         }
 666         /*
 667          * The following entry is free, merge with it.
 668          */
 669         else if (postdup) {
 670                 dfp = xfs_dir2_data_freefind(hdr, postdup);
 671                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
 672                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 673                 newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
 674                 *xfs_dir2_data_unused_tag_p(newdup) =
 675                         cpu_to_be16((char *)newdup - (char *)hdr);
 676                 xfs_dir2_data_log_unused(tp, bp, newdup);
 677                 /*
 678                  * If the following entry was in the table, the new entry
 679                  * is longer, so it will be in the table too.  Remove
 680                  * the old one and add the new one.
 681                  */
 682                 if (dfp) {
 683                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 684                         xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 685                 }
 686                 /*
 687                  * Otherwise we need a scan if the new entry is big enough.
 688                  */
 689                 else {
 690                         needscan = be16_to_cpu(newdup->length) >
 691                                    be16_to_cpu(hdr->bestfree[2].length);
 692                 }
 693         }
 694         /*
 695          * Neither neighbor is free.  Make a new entry.
 696          */
 697         else {
 698                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
 699                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 700                 newdup->length = cpu_to_be16(len);
 701                 *xfs_dir2_data_unused_tag_p(newdup) =
 702                         cpu_to_be16((char *)newdup - (char *)hdr);
 703                 xfs_dir2_data_log_unused(tp, bp, newdup);
 704                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 705         }
 706         *needscanp = needscan;
 707 }
 708
 709 /*
 710  * Take a byte range out of an existing unused space and make it un-free.
 711  */
 712 void
 713 xfs_dir2_data_use_free(
 714         struct xfs_trans        *tp,
 715         struct xfs_buf          *bp,
 716         xfs_dir2_data_unused_t  *dup,           /* unused entry */
 717         xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
 718         xfs_dir2_data_aoff_t    len,            /* length to use */
 719         int                     *needlogp,      /* out: need to log header */
 720         int                     *needscanp)     /* out: need regen bestfree */
 721 {
 722         xfs_dir2_data_hdr_t     *hdr;           /* data block header */
 723         xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 724         int                     matchback;      /* matches end of freespace */
 725         int                     matchfront;     /* matches start of freespace */
 726         int                     needscan;       /* need to regen bestfree */
 727         xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 728         xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
 729         int                     oldlen;         /* old unused entry's length */
 730
 731         hdr = bp->b_addr;
 732         ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
 733                hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC));
 734         ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
 735         ASSERT(offset >= (char *)dup - (char *)hdr);
 736         ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)hdr);
 737         ASSERT((char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 738         /*
 739          * Look up the entry in the bestfree table.
 740          */
 741         dfp = xfs_dir2_data_freefind(hdr, dup);
 742         oldlen = be16_to_cpu(dup->length);
 743         ASSERT(dfp || oldlen <= be16_to_cpu(hdr->bestfree[2].length));
 744         /*
 745          * Check for alignment with front and back of the entry.
 746          */
 747         matchfront = (char *)dup - (char *)hdr == offset;
 748         matchback = (char *)dup + oldlen - (char *)hdr == offset + len;
 749         ASSERT(*needscanp == 0);
 750         needscan = 0;
 751         /*
 752          * If we matched it exactly we just need to get rid of it from
 753          * the bestfree table.
 754          */
 755         if (matchfront && matchback) {
 756                 if (dfp) {
 757                         needscan = (hdr->bestfree[2].offset != 0);
 758                         if (!needscan)
 759                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 760                 }
 761         }
 762         /*
 763          * We match the first part of the entry.
 764          * Make a new entry with the remaining freespace.
 765          */
 766         else if (matchfront) {
 767                 newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 768                 newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 769                 newdup->length = cpu_to_be16(oldlen - len);
 770                 *xfs_dir2_data_unused_tag_p(newdup) =
 771                         cpu_to_be16((char *)newdup - (char *)hdr);
 772                 xfs_dir2_data_log_unused(tp, bp, newdup);
 773                 /*
 774                  * If it was in the table, remove it and add the new one.
 775                  */
 776                 if (dfp) {
 777                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 778                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 779                         ASSERT(dfp != NULL);
 780                         ASSERT(dfp->length == newdup->length);
 781                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
 782                         /*
 783                          * If we got inserted at the last slot,
 784                          * that means we don't know if there was a better
 785                          * choice for the last slot, or not.  Rescan.
 786                          */
 787                         needscan = dfp == &hdr->bestfree[2];
 788                 }
 789         }
 790         /*
 791          * We match the last part of the entry.
 792          * Trim the allocated space off the tail of the entry.
 793          */
 794         else if (matchback) {
 795                 newdup = dup;
 796                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
 797                 *xfs_dir2_data_unused_tag_p(newdup) =
 798                         cpu_to_be16((char *)newdup - (char *)hdr);
 799                 xfs_dir2_data_log_unused(tp, bp, newdup);
 800                 /*
 801                  * If it was in the table, remove it and add the new one.
 802                  */
 803                 if (dfp) {
 804                         xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 805                         dfp = xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 806                         ASSERT(dfp != NULL);
 807                         ASSERT(dfp->length == newdup->length);
 808                         ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
 809                         /*
 810                          * If we got inserted at the last slot,
 811                          * that means we don't know if there was a better
 812                          * choice for the last slot, or not.  Rescan.
 813                          */
 814                         needscan = dfp == &hdr->bestfree[2];
 815                 }
 816         }
 817         /*
 818          * Poking out the middle of an entry.
 819          * Make two new entries.
 820          */
 821         else {
 822                 newdup = dup;
 823                 newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
 824                 *xfs_dir2_data_unused_tag_p(newdup) =
 825                         cpu_to_be16((char *)newdup - (char *)hdr);
 826                 xfs_dir2_data_log_unused(tp, bp, newdup);
 827                 newdup2 = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
 828                 newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 829                 newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
 830                 *xfs_dir2_data_unused_tag_p(newdup2) =
 831                         cpu_to_be16((char *)newdup2 - (char *)hdr);
 832                 xfs_dir2_data_log_unused(tp, bp, newdup2);
 833                 /*
 834                  * If the old entry was in the table, we need to scan
 835                  * if the 3rd entry was valid, since these entries
 836                  * are smaller than the old one.
 837                  * If we don't need to scan that means there were 1 or 2
 838                  * entries in the table, and removing the old and adding
 839                  * the 2 new will work.
 840                  */
 841                 if (dfp) {
 842                         needscan = (hdr->bestfree[2].length != 0);
 843                         if (!needscan) {
 844                                 xfs_dir2_data_freeremove(hdr, dfp, needlogp);
 845                                 xfs_dir2_data_freeinsert(hdr, newdup, needlogp);
 846                                 xfs_dir2_data_freeinsert(hdr, newdup2,
 847                                                          needlogp);
 848                         }
 849                 }
 850         }
 851         *needscanp = needscan;
 852 }