linux/fs/xfs/xfs_dir2_data.c
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   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 */
  46void
  47xfs_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        struct xfs_name         name;
  69
  70        mp = dp->i_mount;
  71        d = bp->data;
  72        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
  73               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
  74        bf = d->hdr.bestfree;
  75        p = (char *)d->u;
  76        if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
  77                btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
  78                lep = xfs_dir2_block_leaf_p(btp);
  79                endp = (char *)lep;
  80        } else
  81                endp = (char *)d + mp->m_dirblksize;
  82        count = lastfree = freeseen = 0;
  83        /*
  84         * Account for zero bestfree entries.
  85         */
  86        if (!bf[0].length) {
  87                ASSERT(!bf[0].offset);
  88                freeseen |= 1 << 0;
  89        }
  90        if (!bf[1].length) {
  91                ASSERT(!bf[1].offset);
  92                freeseen |= 1 << 1;
  93        }
  94        if (!bf[2].length) {
  95                ASSERT(!bf[2].offset);
  96                freeseen |= 1 << 2;
  97        }
  98        ASSERT(be16_to_cpu(bf[0].length) >= be16_to_cpu(bf[1].length));
  99        ASSERT(be16_to_cpu(bf[1].length) >= be16_to_cpu(bf[2].length));
 100        /*
 101         * Loop over the data/unused entries.
 102         */
 103        while (p < endp) {
 104                dup = (xfs_dir2_data_unused_t *)p;
 105                /*
 106                 * If it's unused, look for the space in the bestfree table.
 107                 * If we find it, account for that, else make sure it
 108                 * doesn't need to be there.
 109                 */
 110                if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 111                        ASSERT(lastfree == 0);
 112                        ASSERT(be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
 113                               (char *)dup - (char *)d);
 114                        dfp = xfs_dir2_data_freefind(d, dup);
 115                        if (dfp) {
 116                                i = (int)(dfp - bf);
 117                                ASSERT((freeseen & (1 << i)) == 0);
 118                                freeseen |= 1 << i;
 119                        } else {
 120                                ASSERT(be16_to_cpu(dup->length) <=
 121                                       be16_to_cpu(bf[2].length));
 122                        }
 123                        p += be16_to_cpu(dup->length);
 124                        lastfree = 1;
 125                        continue;
 126                }
 127                /*
 128                 * It's a real entry.  Validate the fields.
 129                 * If this is a block directory then make sure it's
 130                 * in the leaf section of the block.
 131                 * The linear search is crude but this is DEBUG code.
 132                 */
 133                dep = (xfs_dir2_data_entry_t *)p;
 134                ASSERT(dep->namelen != 0);
 135                ASSERT(xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)) == 0);
 136                ASSERT(be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
 137                       (char *)dep - (char *)d);
 138                count++;
 139                lastfree = 0;
 140                if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 141                        addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
 142                                (xfs_dir2_data_aoff_t)
 143                                ((char *)dep - (char *)d));
 144                        name.name = dep->name;
 145                        name.len = dep->namelen;
 146                        hash = mp->m_dirnameops->hashname(&name);
 147                        for (i = 0; i < be32_to_cpu(btp->count); i++) {
 148                                if (be32_to_cpu(lep[i].address) == addr &&
 149                                    be32_to_cpu(lep[i].hashval) == hash)
 150                                        break;
 151                        }
 152                        ASSERT(i < be32_to_cpu(btp->count));
 153                }
 154                p += xfs_dir2_data_entsize(dep->namelen);
 155        }
 156        /*
 157         * Need to have seen all the entries and all the bestfree slots.
 158         */
 159        ASSERT(freeseen == 7);
 160        if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 161                for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
 162                        if (be32_to_cpu(lep[i].address) == 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 */
 177xfs_dir2_data_free_t *
 178xfs_dir2_data_freefind(
 179        xfs_dir2_data_t         *d,             /* 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 *)d);
 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(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 197               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 198        for (dfp = &d->hdr.bestfree[0], seenzero = matched = 0;
 199             dfp < &d->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 > &d->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(d->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 = &d->hdr.bestfree[0];
 230             dfp < &d->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 */
 246xfs_dir2_data_free_t *                          /* entry inserted */
 247xfs_dir2_data_freeinsert(
 248        xfs_dir2_data_t         *d,             /* 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(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 257               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 258#endif
 259        dfp = d->hdr.bestfree;
 260        new.length = dup->length;
 261        new.offset = cpu_to_be16((char *)dup - (char *)d);
 262        /*
 263         * Insert at position 0, 1, or 2; or not at all.
 264         */
 265        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
 266                dfp[2] = dfp[1];
 267                dfp[1] = dfp[0];
 268                dfp[0] = new;
 269                *loghead = 1;
 270                return &dfp[0];
 271        }
 272        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
 273                dfp[2] = dfp[1];
 274                dfp[1] = new;
 275                *loghead = 1;
 276                return &dfp[1];
 277        }
 278        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
 279                dfp[2] = new;
 280                *loghead = 1;
 281                return &dfp[2];
 282        }
 283        return NULL;
 284}
 285
 286/*
 287 * Remove a bestfree entry from the table.
 288 */
 289STATIC void
 290xfs_dir2_data_freeremove(
 291        xfs_dir2_data_t         *d,             /* data block pointer */
 292        xfs_dir2_data_free_t    *dfp,           /* bestfree entry pointer */
 293        int                     *loghead)       /* out: log data header */
 294{
 295#ifdef __KERNEL__
 296        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 297               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 298#endif
 299        /*
 300         * It's the first entry, slide the next 2 up.
 301         */
 302        if (dfp == &d->hdr.bestfree[0]) {
 303                d->hdr.bestfree[0] = d->hdr.bestfree[1];
 304                d->hdr.bestfree[1] = d->hdr.bestfree[2];
 305        }
 306        /*
 307         * It's the second entry, slide the 3rd entry up.
 308         */
 309        else if (dfp == &d->hdr.bestfree[1])
 310                d->hdr.bestfree[1] = d->hdr.bestfree[2];
 311        /*
 312         * Must be the last entry.
 313         */
 314        else
 315                ASSERT(dfp == &d->hdr.bestfree[2]);
 316        /*
 317         * Clear the 3rd entry, must be zero now.
 318         */
 319        d->hdr.bestfree[2].length = 0;
 320        d->hdr.bestfree[2].offset = 0;
 321        *loghead = 1;
 322}
 323
 324/*
 325 * Given a data block, reconstruct its bestfree map.
 326 */
 327void
 328xfs_dir2_data_freescan(
 329        xfs_mount_t             *mp,            /* filesystem mount point */
 330        xfs_dir2_data_t         *d,             /* data block pointer */
 331        int                     *loghead)       /* out: log data header */
 332{
 333        xfs_dir2_block_tail_t   *btp;           /* block tail */
 334        xfs_dir2_data_entry_t   *dep;           /* active data entry */
 335        xfs_dir2_data_unused_t  *dup;           /* unused data entry */
 336        char                    *endp;          /* end of block's data */
 337        char                    *p;             /* current entry pointer */
 338
 339#ifdef __KERNEL__
 340        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 341               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 342#endif
 343        /*
 344         * Start by clearing the table.
 345         */
 346        memset(d->hdr.bestfree, 0, sizeof(d->hdr.bestfree));
 347        *loghead = 1;
 348        /*
 349         * Set up pointers.
 350         */
 351        p = (char *)d->u;
 352        if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
 353                btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 354                endp = (char *)xfs_dir2_block_leaf_p(btp);
 355        } else
 356                endp = (char *)d + mp->m_dirblksize;
 357        /*
 358         * Loop over the block's entries.
 359         */
 360        while (p < endp) {
 361                dup = (xfs_dir2_data_unused_t *)p;
 362                /*
 363                 * If it's a free entry, insert it.
 364                 */
 365                if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
 366                        ASSERT((char *)dup - (char *)d ==
 367                               be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 368                        xfs_dir2_data_freeinsert(d, dup, loghead);
 369                        p += be16_to_cpu(dup->length);
 370                }
 371                /*
 372                 * For active entries, check their tags and skip them.
 373                 */
 374                else {
 375                        dep = (xfs_dir2_data_entry_t *)p;
 376                        ASSERT((char *)dep - (char *)d ==
 377                               be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
 378                        p += xfs_dir2_data_entsize(dep->namelen);
 379                }
 380        }
 381}
 382
 383/*
 384 * Initialize a data block at the given block number in the directory.
 385 * Give back the buffer for the created block.
 386 */
 387int                                             /* error */
 388xfs_dir2_data_init(
 389        xfs_da_args_t           *args,          /* directory operation args */
 390        xfs_dir2_db_t           blkno,          /* logical dir block number */
 391        xfs_dabuf_t             **bpp)          /* output block buffer */
 392{
 393        xfs_dabuf_t             *bp;            /* block buffer */
 394        xfs_dir2_data_t         *d;             /* pointer to block */
 395        xfs_inode_t             *dp;            /* incore directory inode */
 396        xfs_dir2_data_unused_t  *dup;           /* unused entry pointer */
 397        int                     error;          /* error return value */
 398        int                     i;              /* bestfree index */
 399        xfs_mount_t             *mp;            /* filesystem mount point */
 400        xfs_trans_t             *tp;            /* transaction pointer */
 401        int                     t;              /* temp */
 402
 403        dp = args->dp;
 404        mp = dp->i_mount;
 405        tp = args->trans;
 406        /*
 407         * Get the buffer set up for the block.
 408         */
 409        error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
 410                XFS_DATA_FORK);
 411        if (error) {
 412                return error;
 413        }
 414        ASSERT(bp != NULL);
 415        /*
 416         * Initialize the header.
 417         */
 418        d = bp->data;
 419        d->hdr.magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
 420        d->hdr.bestfree[0].offset = cpu_to_be16(sizeof(d->hdr));
 421        for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
 422                d->hdr.bestfree[i].length = 0;
 423                d->hdr.bestfree[i].offset = 0;
 424        }
 425        /*
 426         * Set up an unused entry for the block's body.
 427         */
 428        dup = &d->u[0].unused;
 429        dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 430
 431        t=mp->m_dirblksize - (uint)sizeof(d->hdr);
 432        d->hdr.bestfree[0].length = cpu_to_be16(t);
 433        dup->length = cpu_to_be16(t);
 434        *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)d);
 435        /*
 436         * Log it and return it.
 437         */
 438        xfs_dir2_data_log_header(tp, bp);
 439        xfs_dir2_data_log_unused(tp, bp, dup);
 440        *bpp = bp;
 441        return 0;
 442}
 443
 444/*
 445 * Log an active data entry from the block.
 446 */
 447void
 448xfs_dir2_data_log_entry(
 449        xfs_trans_t             *tp,            /* transaction pointer */
 450        xfs_dabuf_t             *bp,            /* block buffer */
 451        xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
 452{
 453        xfs_dir2_data_t         *d;             /* data block pointer */
 454
 455        d = bp->data;
 456        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 457               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 458        xfs_da_log_buf(tp, bp, (uint)((char *)dep - (char *)d),
 459                (uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
 460                       (char *)d - 1));
 461}
 462
 463/*
 464 * Log a data block header.
 465 */
 466void
 467xfs_dir2_data_log_header(
 468        xfs_trans_t             *tp,            /* transaction pointer */
 469        xfs_dabuf_t             *bp)            /* block buffer */
 470{
 471        xfs_dir2_data_t         *d;             /* data block pointer */
 472
 473        d = bp->data;
 474        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 475               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 476        xfs_da_log_buf(tp, bp, (uint)((char *)&d->hdr - (char *)d),
 477                (uint)(sizeof(d->hdr) - 1));
 478}
 479
 480/*
 481 * Log a data unused entry.
 482 */
 483void
 484xfs_dir2_data_log_unused(
 485        xfs_trans_t             *tp,            /* transaction pointer */
 486        xfs_dabuf_t             *bp,            /* block buffer */
 487        xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
 488{
 489        xfs_dir2_data_t         *d;             /* data block pointer */
 490
 491        d = bp->data;
 492        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 493               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 494        /*
 495         * Log the first part of the unused entry.
 496         */
 497        xfs_da_log_buf(tp, bp, (uint)((char *)dup - (char *)d),
 498                (uint)((char *)&dup->length + sizeof(dup->length) -
 499                       1 - (char *)d));
 500        /*
 501         * Log the end (tag) of the unused entry.
 502         */
 503        xfs_da_log_buf(tp, bp,
 504                (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d),
 505                (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d +
 506                       sizeof(xfs_dir2_data_off_t) - 1));
 507}
 508
 509/*
 510 * Make a byte range in the data block unused.
 511 * Its current contents are unimportant.
 512 */
 513void
 514xfs_dir2_data_make_free(
 515        xfs_trans_t             *tp,            /* transaction pointer */
 516        xfs_dabuf_t             *bp,            /* block buffer */
 517        xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
 518        xfs_dir2_data_aoff_t    len,            /* length in bytes */
 519        int                     *needlogp,      /* out: log header */
 520        int                     *needscanp)     /* out: regen bestfree */
 521{
 522        xfs_dir2_data_t         *d;             /* data block pointer */
 523        xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 524        char                    *endptr;        /* end of data area */
 525        xfs_mount_t             *mp;            /* filesystem mount point */
 526        int                     needscan;       /* need to regen bestfree */
 527        xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 528        xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
 529        xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
 530
 531        mp = tp->t_mountp;
 532        d = bp->data;
 533        /*
 534         * Figure out where the end of the data area is.
 535         */
 536        if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC)
 537                endptr = (char *)d + mp->m_dirblksize;
 538        else {
 539                xfs_dir2_block_tail_t   *btp;   /* block tail */
 540
 541                ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 542                btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
 543                endptr = (char *)xfs_dir2_block_leaf_p(btp);
 544        }
 545        /*
 546         * If this isn't the start of the block, then back up to
 547         * the previous entry and see if it's free.
 548         */
 549        if (offset > sizeof(d->hdr)) {
 550                __be16                  *tagp;  /* tag just before us */
 551
 552                tagp = (__be16 *)((char *)d + offset) - 1;
 553                prevdup = (xfs_dir2_data_unused_t *)((char *)d + be16_to_cpu(*tagp));
 554                if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 555                        prevdup = NULL;
 556        } else
 557                prevdup = NULL;
 558        /*
 559         * If this isn't the end of the block, see if the entry after
 560         * us is free.
 561         */
 562        if ((char *)d + offset + len < endptr) {
 563                postdup =
 564                        (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 565                if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
 566                        postdup = NULL;
 567        } else
 568                postdup = NULL;
 569        ASSERT(*needscanp == 0);
 570        needscan = 0;
 571        /*
 572         * Previous and following entries are both free,
 573         * merge everything into a single free entry.
 574         */
 575        if (prevdup && postdup) {
 576                xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */
 577
 578                /*
 579                 * See if prevdup and/or postdup are in bestfree table.
 580                 */
 581                dfp = xfs_dir2_data_freefind(d, prevdup);
 582                dfp2 = xfs_dir2_data_freefind(d, postdup);
 583                /*
 584                 * We need a rescan unless there are exactly 2 free entries
 585                 * namely our two.  Then we know what's happening, otherwise
 586                 * since the third bestfree is there, there might be more
 587                 * entries.
 588                 */
 589                needscan = (d->hdr.bestfree[2].length != 0);
 590                /*
 591                 * Fix up the new big freespace.
 592                 */
 593                be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
 594                *xfs_dir2_data_unused_tag_p(prevdup) =
 595                        cpu_to_be16((char *)prevdup - (char *)d);
 596                xfs_dir2_data_log_unused(tp, bp, prevdup);
 597                if (!needscan) {
 598                        /*
 599                         * Has to be the case that entries 0 and 1 are
 600                         * dfp and dfp2 (don't know which is which), and
 601                         * entry 2 is empty.
 602                         * Remove entry 1 first then entry 0.
 603                         */
 604                        ASSERT(dfp && dfp2);
 605                        if (dfp == &d->hdr.bestfree[1]) {
 606                                dfp = &d->hdr.bestfree[0];
 607                                ASSERT(dfp2 == dfp);
 608                                dfp2 = &d->hdr.bestfree[1];
 609                        }
 610                        xfs_dir2_data_freeremove(d, dfp2, needlogp);
 611                        xfs_dir2_data_freeremove(d, dfp, needlogp);
 612                        /*
 613                         * Now insert the new entry.
 614                         */
 615                        dfp = xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 616                        ASSERT(dfp == &d->hdr.bestfree[0]);
 617                        ASSERT(dfp->length == prevdup->length);
 618                        ASSERT(!dfp[1].length);
 619                        ASSERT(!dfp[2].length);
 620                }
 621        }
 622        /*
 623         * The entry before us is free, merge with it.
 624         */
 625        else if (prevdup) {
 626                dfp = xfs_dir2_data_freefind(d, prevdup);
 627                be16_add_cpu(&prevdup->length, len);
 628                *xfs_dir2_data_unused_tag_p(prevdup) =
 629                        cpu_to_be16((char *)prevdup - (char *)d);
 630                xfs_dir2_data_log_unused(tp, bp, prevdup);
 631                /*
 632                 * If the previous entry was in the table, the new entry
 633                 * is longer, so it will be in the table too.  Remove
 634                 * the old one and add the new one.
 635                 */
 636                if (dfp) {
 637                        xfs_dir2_data_freeremove(d, dfp, needlogp);
 638                        (void)xfs_dir2_data_freeinsert(d, prevdup, needlogp);
 639                }
 640                /*
 641                 * Otherwise we need a scan if the new entry is big enough.
 642                 */
 643                else {
 644                        needscan = be16_to_cpu(prevdup->length) >
 645                                   be16_to_cpu(d->hdr.bestfree[2].length);
 646                }
 647        }
 648        /*
 649         * The following entry is free, merge with it.
 650         */
 651        else if (postdup) {
 652                dfp = xfs_dir2_data_freefind(d, postdup);
 653                newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 654                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 655                newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
 656                *xfs_dir2_data_unused_tag_p(newdup) =
 657                        cpu_to_be16((char *)newdup - (char *)d);
 658                xfs_dir2_data_log_unused(tp, bp, newdup);
 659                /*
 660                 * If the following entry was in the table, the new entry
 661                 * is longer, so it will be in the table too.  Remove
 662                 * the old one and add the new one.
 663                 */
 664                if (dfp) {
 665                        xfs_dir2_data_freeremove(d, dfp, needlogp);
 666                        (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 667                }
 668                /*
 669                 * Otherwise we need a scan if the new entry is big enough.
 670                 */
 671                else {
 672                        needscan = be16_to_cpu(newdup->length) >
 673                                   be16_to_cpu(d->hdr.bestfree[2].length);
 674                }
 675        }
 676        /*
 677         * Neither neighbor is free.  Make a new entry.
 678         */
 679        else {
 680                newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
 681                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 682                newdup->length = cpu_to_be16(len);
 683                *xfs_dir2_data_unused_tag_p(newdup) =
 684                        cpu_to_be16((char *)newdup - (char *)d);
 685                xfs_dir2_data_log_unused(tp, bp, newdup);
 686                (void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
 687        }
 688        *needscanp = needscan;
 689}
 690
 691/*
 692 * Take a byte range out of an existing unused space and make it un-free.
 693 */
 694void
 695xfs_dir2_data_use_free(
 696        xfs_trans_t             *tp,            /* transaction pointer */
 697        xfs_dabuf_t             *bp,            /* data block buffer */
 698        xfs_dir2_data_unused_t  *dup,           /* unused entry */
 699        xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
 700        xfs_dir2_data_aoff_t    len,            /* length to use */
 701        int                     *needlogp,      /* out: need to log header */
 702        int                     *needscanp)     /* out: need regen bestfree */
 703{
 704        xfs_dir2_data_t         *d;             /* data block */
 705        xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
 706        int                     matchback;      /* matches end of freespace */
 707        int                     matchfront;     /* matches start of freespace */
 708        int                     needscan;       /* need to regen bestfree */
 709        xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
 710        xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
 711        int                     oldlen;         /* old unused entry's length */
 712
 713        d = bp->data;
 714        ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
 715               be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
 716        ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
 717        ASSERT(offset >= (char *)dup - (char *)d);
 718        ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)d);
 719        ASSERT((char *)dup - (char *)d == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
 720        /*
 721         * Look up the entry in the bestfree table.
 722         */
 723        dfp = xfs_dir2_data_freefind(d, dup);
 724        oldlen = be16_to_cpu(dup->length);
 725        ASSERT(dfp || oldlen <= be16_to_cpu(d->hdr.bestfree[2].length));
 726        /*
 727         * Check for alignment with front and back of the entry.
 728         */
 729        matchfront = (char *)dup - (char *)d == offset;
 730        matchback = (char *)dup + oldlen - (char *)d == offset + len;
 731        ASSERT(*needscanp == 0);
 732        needscan = 0;
 733        /*
 734         * If we matched it exactly we just need to get rid of it from
 735         * the bestfree table.
 736         */
 737        if (matchfront && matchback) {
 738                if (dfp) {
 739                        needscan = (d->hdr.bestfree[2].offset != 0);
 740                        if (!needscan)
 741                                xfs_dir2_data_freeremove(d, dfp, needlogp);
 742                }
 743        }
 744        /*
 745         * We match the first part of the entry.
 746         * Make a new entry with the remaining freespace.
 747         */
 748        else if (matchfront) {
 749                newdup = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 750                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 751                newdup->length = cpu_to_be16(oldlen - len);
 752                *xfs_dir2_data_unused_tag_p(newdup) =
 753                        cpu_to_be16((char *)newdup - (char *)d);
 754                xfs_dir2_data_log_unused(tp, bp, newdup);
 755                /*
 756                 * If it was in the table, remove it and add the new one.
 757                 */
 758                if (dfp) {
 759                        xfs_dir2_data_freeremove(d, dfp, needlogp);
 760                        dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 761                        ASSERT(dfp != NULL);
 762                        ASSERT(dfp->length == newdup->length);
 763                        ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 764                        /*
 765                         * If we got inserted at the last slot,
 766                         * that means we don't know if there was a better
 767                         * choice for the last slot, or not.  Rescan.
 768                         */
 769                        needscan = dfp == &d->hdr.bestfree[2];
 770                }
 771        }
 772        /*
 773         * We match the last part of the entry.
 774         * Trim the allocated space off the tail of the entry.
 775         */
 776        else if (matchback) {
 777                newdup = dup;
 778                newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 779                *xfs_dir2_data_unused_tag_p(newdup) =
 780                        cpu_to_be16((char *)newdup - (char *)d);
 781                xfs_dir2_data_log_unused(tp, bp, newdup);
 782                /*
 783                 * If it was in the table, remove it and add the new one.
 784                 */
 785                if (dfp) {
 786                        xfs_dir2_data_freeremove(d, dfp, needlogp);
 787                        dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
 788                        ASSERT(dfp != NULL);
 789                        ASSERT(dfp->length == newdup->length);
 790                        ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
 791                        /*
 792                         * If we got inserted at the last slot,
 793                         * that means we don't know if there was a better
 794                         * choice for the last slot, or not.  Rescan.
 795                         */
 796                        needscan = dfp == &d->hdr.bestfree[2];
 797                }
 798        }
 799        /*
 800         * Poking out the middle of an entry.
 801         * Make two new entries.
 802         */
 803        else {
 804                newdup = dup;
 805                newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
 806                *xfs_dir2_data_unused_tag_p(newdup) =
 807                        cpu_to_be16((char *)newdup - (char *)d);
 808                xfs_dir2_data_log_unused(tp, bp, newdup);
 809                newdup2 = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
 810                newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
 811                newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
 812                *xfs_dir2_data_unused_tag_p(newdup2) =
 813                        cpu_to_be16((char *)newdup2 - (char *)d);
 814                xfs_dir2_data_log_unused(tp, bp, newdup2);
 815                /*
 816                 * If the old entry was in the table, we need to scan
 817                 * if the 3rd entry was valid, since these entries
 818                 * are smaller than the old one.
 819                 * If we don't need to scan that means there were 1 or 2
 820                 * entries in the table, and removing the old and adding
 821                 * the 2 new will work.
 822                 */
 823                if (dfp) {
 824                        needscan = (d->hdr.bestfree[2].length != 0);
 825                        if (!needscan) {
 826                                xfs_dir2_data_freeremove(d, dfp, needlogp);
 827                                (void)xfs_dir2_data_freeinsert(d, newdup,
 828                                        needlogp);
 829                                (void)xfs_dir2_data_freeinsert(d, newdup2,
 830                                        needlogp);
 831                        }
 832                }
 833        }
 834        *needscanp = needscan;
 835}
 836
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