linux/fs/jfs/jfs_dmap.c
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   1/*
   2 *   Copyright (C) International Business Machines Corp., 2000-2004
   3 *
   4 *   This program is free software;  you can redistribute it and/or modify
   5 *   it under the terms of the GNU General Public License as published by
   6 *   the Free Software Foundation; either version 2 of the License, or
   7 *   (at your option) any later version.
   8 *
   9 *   This program is distributed in the hope that it will be useful,
  10 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
  11 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  12 *   the 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 to the Free Software
  16 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17 */
  18
  19#include <linux/fs.h>
  20#include <linux/slab.h>
  21#include "jfs_incore.h"
  22#include "jfs_superblock.h"
  23#include "jfs_dmap.h"
  24#include "jfs_imap.h"
  25#include "jfs_lock.h"
  26#include "jfs_metapage.h"
  27#include "jfs_debug.h"
  28
  29/*
  30 *      SERIALIZATION of the Block Allocation Map.
  31 *
  32 *      the working state of the block allocation map is accessed in
  33 *      two directions:
  34 *
  35 *      1) allocation and free requests that start at the dmap
  36 *         level and move up through the dmap control pages (i.e.
  37 *         the vast majority of requests).
  38 *
  39 *      2) allocation requests that start at dmap control page
  40 *         level and work down towards the dmaps.
  41 *
  42 *      the serialization scheme used here is as follows.
  43 *
  44 *      requests which start at the bottom are serialized against each
  45 *      other through buffers and each requests holds onto its buffers
  46 *      as it works it way up from a single dmap to the required level
  47 *      of dmap control page.
  48 *      requests that start at the top are serialized against each other
  49 *      and request that start from the bottom by the multiple read/single
  50 *      write inode lock of the bmap inode. requests starting at the top
  51 *      take this lock in write mode while request starting at the bottom
  52 *      take the lock in read mode.  a single top-down request may proceed
  53 *      exclusively while multiple bottoms-up requests may proceed
  54 *      simultaneously (under the protection of busy buffers).
  55 *
  56 *      in addition to information found in dmaps and dmap control pages,
  57 *      the working state of the block allocation map also includes read/
  58 *      write information maintained in the bmap descriptor (i.e. total
  59 *      free block count, allocation group level free block counts).
  60 *      a single exclusive lock (BMAP_LOCK) is used to guard this information
  61 *      in the face of multiple-bottoms up requests.
  62 *      (lock ordering: IREAD_LOCK, BMAP_LOCK);
  63 *
  64 *      accesses to the persistent state of the block allocation map (limited
  65 *      to the persistent bitmaps in dmaps) is guarded by (busy) buffers.
  66 */
  67
  68#define BMAP_LOCK_INIT(bmp)     mutex_init(&bmp->db_bmaplock)
  69#define BMAP_LOCK(bmp)          mutex_lock(&bmp->db_bmaplock)
  70#define BMAP_UNLOCK(bmp)        mutex_unlock(&bmp->db_bmaplock)
  71
  72/*
  73 * forward references
  74 */
  75static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
  76                        int nblocks);
  77static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval);
  78static int dbBackSplit(dmtree_t * tp, int leafno);
  79static int dbJoin(dmtree_t * tp, int leafno, int newval);
  80static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
  81static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
  82                    int level);
  83static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results);
  84static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
  85                       int nblocks);
  86static int dbAllocNear(struct bmap * bmp, struct dmap * dp, s64 blkno,
  87                       int nblocks,
  88                       int l2nb, s64 * results);
  89static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
  90                       int nblocks);
  91static int dbAllocDmapLev(struct bmap * bmp, struct dmap * dp, int nblocks,
  92                          int l2nb,
  93                          s64 * results);
  94static int dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb,
  95                     s64 * results);
  96static int dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno,
  97                      s64 * results);
  98static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks);
  99static int dbFindBits(u32 word, int l2nb);
 100static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno);
 101static int dbFindLeaf(dmtree_t * tp, int l2nb, int *leafidx);
 102static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 103                      int nblocks);
 104static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
 105                      int nblocks);
 106static int dbMaxBud(u8 * cp);
 107s64 dbMapFileSizeToMapSize(struct inode *ipbmap);
 108static int blkstol2(s64 nb);
 109
 110static int cntlz(u32 value);
 111static int cnttz(u32 word);
 112
 113static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
 114                         int nblocks);
 115static int dbInitDmap(struct dmap * dp, s64 blkno, int nblocks);
 116static int dbInitDmapTree(struct dmap * dp);
 117static int dbInitTree(struct dmaptree * dtp);
 118static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i);
 119static int dbGetL2AGSize(s64 nblocks);
 120
 121/*
 122 *      buddy table
 123 *
 124 * table used for determining buddy sizes within characters of
 125 * dmap bitmap words.  the characters themselves serve as indexes
 126 * into the table, with the table elements yielding the maximum
 127 * binary buddy of free bits within the character.
 128 */
 129static const s8 budtab[256] = {
 130        3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 131        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 132        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 133        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 134        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 135        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 136        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 137        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 138        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 139        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 140        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 141        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 142        2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 143        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 144        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
 145        2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -1
 146};
 147
 148
 149/*
 150 * NAME:        dbMount()
 151 *
 152 * FUNCTION:    initializate the block allocation map.
 153 *
 154 *              memory is allocated for the in-core bmap descriptor and
 155 *              the in-core descriptor is initialized from disk.
 156 *
 157 * PARAMETERS:
 158 *      ipbmap  - pointer to in-core inode for the block map.
 159 *
 160 * RETURN VALUES:
 161 *      0       - success
 162 *      -ENOMEM - insufficient memory
 163 *      -EIO    - i/o error
 164 */
 165int dbMount(struct inode *ipbmap)
 166{
 167        struct bmap *bmp;
 168        struct dbmap_disk *dbmp_le;
 169        struct metapage *mp;
 170        int i;
 171
 172        /*
 173         * allocate/initialize the in-memory bmap descriptor
 174         */
 175        /* allocate memory for the in-memory bmap descriptor */
 176        bmp = kmalloc(sizeof(struct bmap), GFP_KERNEL);
 177        if (bmp == NULL)
 178                return -ENOMEM;
 179
 180        /* read the on-disk bmap descriptor. */
 181        mp = read_metapage(ipbmap,
 182                           BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
 183                           PSIZE, 0);
 184        if (mp == NULL) {
 185                kfree(bmp);
 186                return -EIO;
 187        }
 188
 189        /* copy the on-disk bmap descriptor to its in-memory version. */
 190        dbmp_le = (struct dbmap_disk *) mp->data;
 191        bmp->db_mapsize = le64_to_cpu(dbmp_le->dn_mapsize);
 192        bmp->db_nfree = le64_to_cpu(dbmp_le->dn_nfree);
 193        bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage);
 194        bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag);
 195        bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel);
 196        bmp->db_maxag = le32_to_cpu(dbmp_le->dn_maxag);
 197        bmp->db_agpref = le32_to_cpu(dbmp_le->dn_agpref);
 198        bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
 199        bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
 200        bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
 201        bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
 202        bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
 203        for (i = 0; i < MAXAG; i++)
 204                bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]);
 205        bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize);
 206        bmp->db_maxfreebud = dbmp_le->dn_maxfreebud;
 207
 208        /* release the buffer. */
 209        release_metapage(mp);
 210
 211        /* bind the bmap inode and the bmap descriptor to each other. */
 212        bmp->db_ipbmap = ipbmap;
 213        JFS_SBI(ipbmap->i_sb)->bmap = bmp;
 214
 215        memset(bmp->db_active, 0, sizeof(bmp->db_active));
 216
 217        /*
 218         * allocate/initialize the bmap lock
 219         */
 220        BMAP_LOCK_INIT(bmp);
 221
 222        return (0);
 223}
 224
 225
 226/*
 227 * NAME:        dbUnmount()
 228 *
 229 * FUNCTION:    terminate the block allocation map in preparation for
 230 *              file system unmount.
 231 *
 232 *              the in-core bmap descriptor is written to disk and
 233 *              the memory for this descriptor is freed.
 234 *
 235 * PARAMETERS:
 236 *      ipbmap  - pointer to in-core inode for the block map.
 237 *
 238 * RETURN VALUES:
 239 *      0       - success
 240 *      -EIO    - i/o error
 241 */
 242int dbUnmount(struct inode *ipbmap, int mounterror)
 243{
 244        struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
 245
 246        if (!(mounterror || isReadOnly(ipbmap)))
 247                dbSync(ipbmap);
 248
 249        /*
 250         * Invalidate the page cache buffers
 251         */
 252        truncate_inode_pages(ipbmap->i_mapping, 0);
 253
 254        /* free the memory for the in-memory bmap. */
 255        kfree(bmp);
 256
 257        return (0);
 258}
 259
 260/*
 261 *      dbSync()
 262 */
 263int dbSync(struct inode *ipbmap)
 264{
 265        struct dbmap_disk *dbmp_le;
 266        struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
 267        struct metapage *mp;
 268        int i;
 269
 270        /*
 271         * write bmap global control page
 272         */
 273        /* get the buffer for the on-disk bmap descriptor. */
 274        mp = read_metapage(ipbmap,
 275                           BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
 276                           PSIZE, 0);
 277        if (mp == NULL) {
 278                jfs_err("dbSync: read_metapage failed!");
 279                return -EIO;
 280        }
 281        /* copy the in-memory version of the bmap to the on-disk version */
 282        dbmp_le = (struct dbmap_disk *) mp->data;
 283        dbmp_le->dn_mapsize = cpu_to_le64(bmp->db_mapsize);
 284        dbmp_le->dn_nfree = cpu_to_le64(bmp->db_nfree);
 285        dbmp_le->dn_l2nbperpage = cpu_to_le32(bmp->db_l2nbperpage);
 286        dbmp_le->dn_numag = cpu_to_le32(bmp->db_numag);
 287        dbmp_le->dn_maxlevel = cpu_to_le32(bmp->db_maxlevel);
 288        dbmp_le->dn_maxag = cpu_to_le32(bmp->db_maxag);
 289        dbmp_le->dn_agpref = cpu_to_le32(bmp->db_agpref);
 290        dbmp_le->dn_aglevel = cpu_to_le32(bmp->db_aglevel);
 291        dbmp_le->dn_agheight = cpu_to_le32(bmp->db_agheight);
 292        dbmp_le->dn_agwidth = cpu_to_le32(bmp->db_agwidth);
 293        dbmp_le->dn_agstart = cpu_to_le32(bmp->db_agstart);
 294        dbmp_le->dn_agl2size = cpu_to_le32(bmp->db_agl2size);
 295        for (i = 0; i < MAXAG; i++)
 296                dbmp_le->dn_agfree[i] = cpu_to_le64(bmp->db_agfree[i]);
 297        dbmp_le->dn_agsize = cpu_to_le64(bmp->db_agsize);
 298        dbmp_le->dn_maxfreebud = bmp->db_maxfreebud;
 299
 300        /* write the buffer */
 301        write_metapage(mp);
 302
 303        /*
 304         * write out dirty pages of bmap
 305         */
 306        filemap_write_and_wait(ipbmap->i_mapping);
 307
 308        diWriteSpecial(ipbmap, 0);
 309
 310        return (0);
 311}
 312
 313
 314/*
 315 * NAME:        dbFree()
 316 *
 317 * FUNCTION:    free the specified block range from the working block
 318 *              allocation map.
 319 *
 320 *              the blocks will be free from the working map one dmap
 321 *              at a time.
 322 *
 323 * PARAMETERS:
 324 *      ip      - pointer to in-core inode;
 325 *      blkno   - starting block number to be freed.
 326 *      nblocks - number of blocks to be freed.
 327 *
 328 * RETURN VALUES:
 329 *      0       - success
 330 *      -EIO    - i/o error
 331 */
 332int dbFree(struct inode *ip, s64 blkno, s64 nblocks)
 333{
 334        struct metapage *mp;
 335        struct dmap *dp;
 336        int nb, rc;
 337        s64 lblkno, rem;
 338        struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
 339        struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
 340
 341        IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
 342
 343        /* block to be freed better be within the mapsize. */
 344        if (unlikely((blkno == 0) || (blkno + nblocks > bmp->db_mapsize))) {
 345                IREAD_UNLOCK(ipbmap);
 346                printk(KERN_ERR "blkno = %Lx, nblocks = %Lx\n",
 347                       (unsigned long long) blkno,
 348                       (unsigned long long) nblocks);
 349                jfs_error(ip->i_sb,
 350                          "dbFree: block to be freed is outside the map");
 351                return -EIO;
 352        }
 353
 354        /*
 355         * free the blocks a dmap at a time.
 356         */
 357        mp = NULL;
 358        for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
 359                /* release previous dmap if any */
 360                if (mp) {
 361                        write_metapage(mp);
 362                }
 363
 364                /* get the buffer for the current dmap. */
 365                lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
 366                mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
 367                if (mp == NULL) {
 368                        IREAD_UNLOCK(ipbmap);
 369                        return -EIO;
 370                }
 371                dp = (struct dmap *) mp->data;
 372
 373                /* determine the number of blocks to be freed from
 374                 * this dmap.
 375                 */
 376                nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
 377
 378                /* free the blocks. */
 379                if ((rc = dbFreeDmap(bmp, dp, blkno, nb))) {
 380                        jfs_error(ip->i_sb, "dbFree: error in block map\n");
 381                        release_metapage(mp);
 382                        IREAD_UNLOCK(ipbmap);
 383                        return (rc);
 384                }
 385        }
 386
 387        /* write the last buffer. */
 388        write_metapage(mp);
 389
 390        IREAD_UNLOCK(ipbmap);
 391
 392        return (0);
 393}
 394
 395
 396/*
 397 * NAME:        dbUpdatePMap()
 398 *
 399 * FUNCTION:    update the allocation state (free or allocate) of the
 400 *              specified block range in the persistent block allocation map.
 401 *
 402 *              the blocks will be updated in the persistent map one
 403 *              dmap at a time.
 404 *
 405 * PARAMETERS:
 406 *      ipbmap  - pointer to in-core inode for the block map.
 407 *      free    - 'true' if block range is to be freed from the persistent
 408 *                map; 'false' if it is to be allocated.
 409 *      blkno   - starting block number of the range.
 410 *      nblocks - number of contiguous blocks in the range.
 411 *      tblk    - transaction block;
 412 *
 413 * RETURN VALUES:
 414 *      0       - success
 415 *      -EIO    - i/o error
 416 */
 417int
 418dbUpdatePMap(struct inode *ipbmap,
 419             int free, s64 blkno, s64 nblocks, struct tblock * tblk)
 420{
 421        int nblks, dbitno, wbitno, rbits;
 422        int word, nbits, nwords;
 423        struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
 424        s64 lblkno, rem, lastlblkno;
 425        u32 mask;
 426        struct dmap *dp;
 427        struct metapage *mp;
 428        struct jfs_log *log;
 429        int lsn, difft, diffp;
 430        unsigned long flags;
 431
 432        /* the blocks better be within the mapsize. */
 433        if (blkno + nblocks > bmp->db_mapsize) {
 434                printk(KERN_ERR "blkno = %Lx, nblocks = %Lx\n",
 435                       (unsigned long long) blkno,
 436                       (unsigned long long) nblocks);
 437                jfs_error(ipbmap->i_sb,
 438                          "dbUpdatePMap: blocks are outside the map");
 439                return -EIO;
 440        }
 441
 442        /* compute delta of transaction lsn from log syncpt */
 443        lsn = tblk->lsn;
 444        log = (struct jfs_log *) JFS_SBI(tblk->sb)->log;
 445        logdiff(difft, lsn, log);
 446
 447        /*
 448         * update the block state a dmap at a time.
 449         */
 450        mp = NULL;
 451        lastlblkno = 0;
 452        for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
 453                /* get the buffer for the current dmap. */
 454                lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
 455                if (lblkno != lastlblkno) {
 456                        if (mp) {
 457                                write_metapage(mp);
 458                        }
 459
 460                        mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE,
 461                                           0);
 462                        if (mp == NULL)
 463                                return -EIO;
 464                        metapage_wait_for_io(mp);
 465                }
 466                dp = (struct dmap *) mp->data;
 467
 468                /* determine the bit number and word within the dmap of
 469                 * the starting block.  also determine how many blocks
 470                 * are to be updated within this dmap.
 471                 */
 472                dbitno = blkno & (BPERDMAP - 1);
 473                word = dbitno >> L2DBWORD;
 474                nblks = min(rem, (s64)BPERDMAP - dbitno);
 475
 476                /* update the bits of the dmap words. the first and last
 477                 * words may only have a subset of their bits updated. if
 478                 * this is the case, we'll work against that word (i.e.
 479                 * partial first and/or last) only in a single pass.  a
 480                 * single pass will also be used to update all words that
 481                 * are to have all their bits updated.
 482                 */
 483                for (rbits = nblks; rbits > 0;
 484                     rbits -= nbits, dbitno += nbits) {
 485                        /* determine the bit number within the word and
 486                         * the number of bits within the word.
 487                         */
 488                        wbitno = dbitno & (DBWORD - 1);
 489                        nbits = min(rbits, DBWORD - wbitno);
 490
 491                        /* check if only part of the word is to be updated. */
 492                        if (nbits < DBWORD) {
 493                                /* update (free or allocate) the bits
 494                                 * in this word.
 495                                 */
 496                                mask =
 497                                    (ONES << (DBWORD - nbits) >> wbitno);
 498                                if (free)
 499                                        dp->pmap[word] &=
 500                                            cpu_to_le32(~mask);
 501                                else
 502                                        dp->pmap[word] |=
 503                                            cpu_to_le32(mask);
 504
 505                                word += 1;
 506                        } else {
 507                                /* one or more words are to have all
 508                                 * their bits updated.  determine how
 509                                 * many words and how many bits.
 510                                 */
 511                                nwords = rbits >> L2DBWORD;
 512                                nbits = nwords << L2DBWORD;
 513
 514                                /* update (free or allocate) the bits
 515                                 * in these words.
 516                                 */
 517                                if (free)
 518                                        memset(&dp->pmap[word], 0,
 519                                               nwords * 4);
 520                                else
 521                                        memset(&dp->pmap[word], (int) ONES,
 522                                               nwords * 4);
 523
 524                                word += nwords;
 525                        }
 526                }
 527
 528                /*
 529                 * update dmap lsn
 530                 */
 531                if (lblkno == lastlblkno)
 532                        continue;
 533
 534                lastlblkno = lblkno;
 535
 536                LOGSYNC_LOCK(log, flags);
 537                if (mp->lsn != 0) {
 538                        /* inherit older/smaller lsn */
 539                        logdiff(diffp, mp->lsn, log);
 540                        if (difft < diffp) {
 541                                mp->lsn = lsn;
 542
 543                                /* move bp after tblock in logsync list */
 544                                list_move(&mp->synclist, &tblk->synclist);
 545                        }
 546
 547                        /* inherit younger/larger clsn */
 548                        logdiff(difft, tblk->clsn, log);
 549                        logdiff(diffp, mp->clsn, log);
 550                        if (difft > diffp)
 551                                mp->clsn = tblk->clsn;
 552                } else {
 553                        mp->log = log;
 554                        mp->lsn = lsn;
 555
 556                        /* insert bp after tblock in logsync list */
 557                        log->count++;
 558                        list_add(&mp->synclist, &tblk->synclist);
 559
 560                        mp->clsn = tblk->clsn;
 561                }
 562                LOGSYNC_UNLOCK(log, flags);
 563        }
 564
 565        /* write the last buffer. */
 566        if (mp) {
 567                write_metapage(mp);
 568        }
 569
 570        return (0);
 571}
 572
 573
 574/*
 575 * NAME:        dbNextAG()
 576 *
 577 * FUNCTION:    find the preferred allocation group for new allocations.
 578 *
 579 *              Within the allocation groups, we maintain a preferred
 580 *              allocation group which consists of a group with at least
 581 *              average free space.  It is the preferred group that we target
 582 *              new inode allocation towards.  The tie-in between inode
 583 *              allocation and block allocation occurs as we allocate the
 584 *              first (data) block of an inode and specify the inode (block)
 585 *              as the allocation hint for this block.
 586 *
 587 *              We try to avoid having more than one open file growing in
 588 *              an allocation group, as this will lead to fragmentation.
 589 *              This differs from the old OS/2 method of trying to keep
 590 *              empty ags around for large allocations.
 591 *
 592 * PARAMETERS:
 593 *      ipbmap  - pointer to in-core inode for the block map.
 594 *
 595 * RETURN VALUES:
 596 *      the preferred allocation group number.
 597 */
 598int dbNextAG(struct inode *ipbmap)
 599{
 600        s64 avgfree;
 601        int agpref;
 602        s64 hwm = 0;
 603        int i;
 604        int next_best = -1;
 605        struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
 606
 607        BMAP_LOCK(bmp);
 608
 609        /* determine the average number of free blocks within the ags. */
 610        avgfree = (u32)bmp->db_nfree / bmp->db_numag;
 611
 612        /*
 613         * if the current preferred ag does not have an active allocator
 614         * and has at least average freespace, return it
 615         */
 616        agpref = bmp->db_agpref;
 617        if ((atomic_read(&bmp->db_active[agpref]) == 0) &&
 618            (bmp->db_agfree[agpref] >= avgfree))
 619                goto unlock;
 620
 621        /* From the last preferred ag, find the next one with at least
 622         * average free space.
 623         */
 624        for (i = 0 ; i < bmp->db_numag; i++, agpref++) {
 625                if (agpref == bmp->db_numag)
 626                        agpref = 0;
 627
 628                if (atomic_read(&bmp->db_active[agpref]))
 629                        /* open file is currently growing in this ag */
 630                        continue;
 631                if (bmp->db_agfree[agpref] >= avgfree) {
 632                        /* Return this one */
 633                        bmp->db_agpref = agpref;
 634                        goto unlock;
 635                } else if (bmp->db_agfree[agpref] > hwm) {
 636                        /* Less than avg. freespace, but best so far */
 637                        hwm = bmp->db_agfree[agpref];
 638                        next_best = agpref;
 639                }
 640        }
 641
 642        /*
 643         * If no inactive ag was found with average freespace, use the
 644         * next best
 645         */
 646        if (next_best != -1)
 647                bmp->db_agpref = next_best;
 648        /* else leave db_agpref unchanged */
 649unlock:
 650        BMAP_UNLOCK(bmp);
 651
 652        /* return the preferred group.
 653         */
 654        return (bmp->db_agpref);
 655}
 656
 657/*
 658 * NAME:        dbAlloc()
 659 *
 660 * FUNCTION:    attempt to allocate a specified number of contiguous free
 661 *              blocks from the working allocation block map.
 662 *
 663 *              the block allocation policy uses hints and a multi-step
 664 *              approach.
 665 *
 666 *              for allocation requests smaller than the number of blocks
 667 *              per dmap, we first try to allocate the new blocks
 668 *              immediately following the hint.  if these blocks are not
 669 *              available, we try to allocate blocks near the hint.  if
 670 *              no blocks near the hint are available, we next try to
 671 *              allocate within the same dmap as contains the hint.
 672 *
 673 *              if no blocks are available in the dmap or the allocation
 674 *              request is larger than the dmap size, we try to allocate
 675 *              within the same allocation group as contains the hint. if
 676 *              this does not succeed, we finally try to allocate anywhere
 677 *              within the aggregate.
 678 *
 679 *              we also try to allocate anywhere within the aggregate for
 680 *              for allocation requests larger than the allocation group
 681 *              size or requests that specify no hint value.
 682 *
 683 * PARAMETERS:
 684 *      ip      - pointer to in-core inode;
 685 *      hint    - allocation hint.
 686 *      nblocks - number of contiguous blocks in the range.
 687 *      results - on successful return, set to the starting block number
 688 *                of the newly allocated contiguous range.
 689 *
 690 * RETURN VALUES:
 691 *      0       - success
 692 *      -ENOSPC - insufficient disk resources
 693 *      -EIO    - i/o error
 694 */
 695int dbAlloc(struct inode *ip, s64 hint, s64 nblocks, s64 * results)
 696{
 697        int rc, agno;
 698        struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
 699        struct bmap *bmp;
 700        struct metapage *mp;
 701        s64 lblkno, blkno;
 702        struct dmap *dp;
 703        int l2nb;
 704        s64 mapSize;
 705        int writers;
 706
 707        /* assert that nblocks is valid */
 708        assert(nblocks > 0);
 709
 710        /* get the log2 number of blocks to be allocated.
 711         * if the number of blocks is not a log2 multiple,
 712         * it will be rounded up to the next log2 multiple.
 713         */
 714        l2nb = BLKSTOL2(nblocks);
 715
 716        bmp = JFS_SBI(ip->i_sb)->bmap;
 717
 718        mapSize = bmp->db_mapsize;
 719
 720        /* the hint should be within the map */
 721        if (hint >= mapSize) {
 722                jfs_error(ip->i_sb, "dbAlloc: the hint is outside the map");
 723                return -EIO;
 724        }
 725
 726        /* if the number of blocks to be allocated is greater than the
 727         * allocation group size, try to allocate anywhere.
 728         */
 729        if (l2nb > bmp->db_agl2size) {
 730                IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
 731
 732                rc = dbAllocAny(bmp, nblocks, l2nb, results);
 733
 734                goto write_unlock;
 735        }
 736
 737        /*
 738         * If no hint, let dbNextAG recommend an allocation group
 739         */
 740        if (hint == 0)
 741                goto pref_ag;
 742
 743        /* we would like to allocate close to the hint.  adjust the
 744         * hint to the block following the hint since the allocators
 745         * will start looking for free space starting at this point.
 746         */
 747        blkno = hint + 1;
 748
 749        if (blkno >= bmp->db_mapsize)
 750                goto pref_ag;
 751
 752        agno = blkno >> bmp->db_agl2size;
 753
 754        /* check if blkno crosses over into a new allocation group.
 755         * if so, check if we should allow allocations within this
 756         * allocation group.
 757         */
 758        if ((blkno & (bmp->db_agsize - 1)) == 0)
 759                /* check if the AG is currently being written to.
 760                 * if so, call dbNextAG() to find a non-busy
 761                 * AG with sufficient free space.
 762                 */
 763                if (atomic_read(&bmp->db_active[agno]))
 764                        goto pref_ag;
 765
 766        /* check if the allocation request size can be satisfied from a
 767         * single dmap.  if so, try to allocate from the dmap containing
 768         * the hint using a tiered strategy.
 769         */
 770        if (nblocks <= BPERDMAP) {
 771                IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
 772
 773                /* get the buffer for the dmap containing the hint.
 774                 */
 775                rc = -EIO;
 776                lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
 777                mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
 778                if (mp == NULL)
 779                        goto read_unlock;
 780
 781                dp = (struct dmap *) mp->data;
 782
 783                /* first, try to satisfy the allocation request with the
 784                 * blocks beginning at the hint.
 785                 */
 786                if ((rc = dbAllocNext(bmp, dp, blkno, (int) nblocks))
 787                    != -ENOSPC) {
 788                        if (rc == 0) {
 789                                *results = blkno;
 790                                mark_metapage_dirty(mp);
 791                        }
 792
 793                        release_metapage(mp);
 794                        goto read_unlock;
 795                }
 796
 797                writers = atomic_read(&bmp->db_active[agno]);
 798                if ((writers > 1) ||
 799                    ((writers == 1) && (JFS_IP(ip)->active_ag != agno))) {
 800                        /*
 801                         * Someone else is writing in this allocation
 802                         * group.  To avoid fragmenting, try another ag
 803                         */
 804                        release_metapage(mp);
 805                        IREAD_UNLOCK(ipbmap);
 806                        goto pref_ag;
 807                }
 808
 809                /* next, try to satisfy the allocation request with blocks
 810                 * near the hint.
 811                 */
 812                if ((rc =
 813                     dbAllocNear(bmp, dp, blkno, (int) nblocks, l2nb, results))
 814                    != -ENOSPC) {
 815                        if (rc == 0)
 816                                mark_metapage_dirty(mp);
 817
 818                        release_metapage(mp);
 819                        goto read_unlock;
 820                }
 821
 822                /* try to satisfy the allocation request with blocks within
 823                 * the same dmap as the hint.
 824                 */
 825                if ((rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results))
 826                    != -ENOSPC) {
 827                        if (rc == 0)
 828                                mark_metapage_dirty(mp);
 829
 830                        release_metapage(mp);
 831                        goto read_unlock;
 832                }
 833
 834                release_metapage(mp);
 835                IREAD_UNLOCK(ipbmap);
 836        }
 837
 838        /* try to satisfy the allocation request with blocks within
 839         * the same allocation group as the hint.
 840         */
 841        IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
 842        if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) != -ENOSPC)
 843                goto write_unlock;
 844
 845        IWRITE_UNLOCK(ipbmap);
 846
 847
 848      pref_ag:
 849        /*
 850         * Let dbNextAG recommend a preferred allocation group
 851         */
 852        agno = dbNextAG(ipbmap);
 853        IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
 854
 855        /* Try to allocate within this allocation group.  if that fails, try to
 856         * allocate anywhere in the map.
 857         */
 858        if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) == -ENOSPC)
 859                rc = dbAllocAny(bmp, nblocks, l2nb, results);
 860
 861      write_unlock:
 862        IWRITE_UNLOCK(ipbmap);
 863
 864        return (rc);
 865
 866      read_unlock:
 867        IREAD_UNLOCK(ipbmap);
 868
 869        return (rc);
 870}
 871
 872#ifdef _NOTYET
 873/*
 874 * NAME:        dbAllocExact()
 875 *
 876 * FUNCTION:    try to allocate the requested extent;
 877 *
 878 * PARAMETERS:
 879 *      ip      - pointer to in-core inode;
 880 *      blkno   - extent address;
 881 *      nblocks - extent length;
 882 *
 883 * RETURN VALUES:
 884 *      0       - success
 885 *      -ENOSPC - insufficient disk resources
 886 *      -EIO    - i/o error
 887 */
 888int dbAllocExact(struct inode *ip, s64 blkno, int nblocks)
 889{
 890        int rc;
 891        struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
 892        struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
 893        struct dmap *dp;
 894        s64 lblkno;
 895        struct metapage *mp;
 896
 897        IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
 898
 899        /*
 900         * validate extent request:
 901         *
 902         * note: defragfs policy:
 903         *  max 64 blocks will be moved.
 904         *  allocation request size must be satisfied from a single dmap.
 905         */
 906        if (nblocks <= 0 || nblocks > BPERDMAP || blkno >= bmp->db_mapsize) {
 907                IREAD_UNLOCK(ipbmap);
 908                return -EINVAL;
 909        }
 910
 911        if (nblocks > ((s64) 1 << bmp->db_maxfreebud)) {
 912                /* the free space is no longer available */
 913                IREAD_UNLOCK(ipbmap);
 914                return -ENOSPC;
 915        }
 916
 917        /* read in the dmap covering the extent */
 918        lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
 919        mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
 920        if (mp == NULL) {
 921                IREAD_UNLOCK(ipbmap);
 922                return -EIO;
 923        }
 924        dp = (struct dmap *) mp->data;
 925
 926        /* try to allocate the requested extent */
 927        rc = dbAllocNext(bmp, dp, blkno, nblocks);
 928
 929        IREAD_UNLOCK(ipbmap);
 930
 931        if (rc == 0)
 932                mark_metapage_dirty(mp);
 933
 934        release_metapage(mp);
 935
 936        return (rc);
 937}
 938#endif /* _NOTYET */
 939
 940/*
 941 * NAME:        dbReAlloc()
 942 *
 943 * FUNCTION:    attempt to extend a current allocation by a specified
 944 *              number of blocks.
 945 *
 946 *              this routine attempts to satisfy the allocation request
 947 *              by first trying to extend the existing allocation in
 948 *              place by allocating the additional blocks as the blocks
 949 *              immediately following the current allocation.  if these
 950 *              blocks are not available, this routine will attempt to
 951 *              allocate a new set of contiguous blocks large enough
 952 *              to cover the existing allocation plus the additional
 953 *              number of blocks required.
 954 *
 955 * PARAMETERS:
 956 *      ip          -  pointer to in-core inode requiring allocation.
 957 *      blkno       -  starting block of the current allocation.
 958 *      nblocks     -  number of contiguous blocks within the current
 959 *                     allocation.
 960 *      addnblocks  -  number of blocks to add to the allocation.
 961 *      results -      on successful return, set to the starting block number
 962 *                     of the existing allocation if the existing allocation
 963 *                     was extended in place or to a newly allocated contiguous
 964 *                     range if the existing allocation could not be extended
 965 *                     in place.
 966 *
 967 * RETURN VALUES:
 968 *      0       - success
 969 *      -ENOSPC - insufficient disk resources
 970 *      -EIO    - i/o error
 971 */
 972int
 973dbReAlloc(struct inode *ip,
 974          s64 blkno, s64 nblocks, s64 addnblocks, s64 * results)
 975{
 976        int rc;
 977
 978        /* try to extend the allocation in place.
 979         */
 980        if ((rc = dbExtend(ip, blkno, nblocks, addnblocks)) == 0) {
 981                *results = blkno;
 982                return (0);
 983        } else {
 984                if (rc != -ENOSPC)
 985                        return (rc);
 986        }
 987
 988        /* could not extend the allocation in place, so allocate a
 989         * new set of blocks for the entire request (i.e. try to get
 990         * a range of contiguous blocks large enough to cover the
 991         * existing allocation plus the additional blocks.)
 992         */
 993        return (dbAlloc
 994                (ip, blkno + nblocks - 1, addnblocks + nblocks, results));
 995}
 996
 997
 998/*
 999 * NAME:        dbExtend()
1000 *
1001 * FUNCTION:    attempt to extend a current allocation by a specified
1002 *              number of blocks.
1003 *
1004 *              this routine attempts to satisfy the allocation request
1005 *              by first trying to extend the existing allocation in
1006 *              place by allocating the additional blocks as the blocks
1007 *              immediately following the current allocation.
1008 *
1009 * PARAMETERS:
1010 *      ip          -  pointer to in-core inode requiring allocation.
1011 *      blkno       -  starting block of the current allocation.
1012 *      nblocks     -  number of contiguous blocks within the current
1013 *                     allocation.
1014 *      addnblocks  -  number of blocks to add to the allocation.
1015 *
1016 * RETURN VALUES:
1017 *      0       - success
1018 *      -ENOSPC - insufficient disk resources
1019 *      -EIO    - i/o error
1020 */
1021static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks)
1022{
1023        struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
1024        s64 lblkno, lastblkno, extblkno;
1025        uint rel_block;
1026        struct metapage *mp;
1027        struct dmap *dp;
1028        int rc;
1029        struct inode *ipbmap = sbi->ipbmap;
1030        struct bmap *bmp;
1031
1032        /*
1033         * We don't want a non-aligned extent to cross a page boundary
1034         */
1035        if (((rel_block = blkno & (sbi->nbperpage - 1))) &&
1036            (rel_block + nblocks + addnblocks > sbi->nbperpage))
1037                return -ENOSPC;
1038
1039        /* get the last block of the current allocation */
1040        lastblkno = blkno + nblocks - 1;
1041
1042        /* determine the block number of the block following
1043         * the existing allocation.
1044         */
1045        extblkno = lastblkno + 1;
1046
1047        IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
1048
1049        /* better be within the file system */
1050        bmp = sbi->bmap;
1051        if (lastblkno < 0 || lastblkno >= bmp->db_mapsize) {
1052                IREAD_UNLOCK(ipbmap);
1053                jfs_error(ip->i_sb,
1054                          "dbExtend: the block is outside the filesystem");
1055                return -EIO;
1056        }
1057
1058        /* we'll attempt to extend the current allocation in place by
1059         * allocating the additional blocks as the blocks immediately
1060         * following the current allocation.  we only try to extend the
1061         * current allocation in place if the number of additional blocks
1062         * can fit into a dmap, the last block of the current allocation
1063         * is not the last block of the file system, and the start of the
1064         * inplace extension is not on an allocation group boundary.
1065         */
1066        if (addnblocks > BPERDMAP || extblkno >= bmp->db_mapsize ||
1067            (extblkno & (bmp->db_agsize - 1)) == 0) {
1068                IREAD_UNLOCK(ipbmap);
1069                return -ENOSPC;
1070        }
1071
1072        /* get the buffer for the dmap containing the first block
1073         * of the extension.
1074         */
1075        lblkno = BLKTODMAP(extblkno, bmp->db_l2nbperpage);
1076        mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
1077        if (mp == NULL) {
1078                IREAD_UNLOCK(ipbmap);
1079                return -EIO;
1080        }
1081
1082        dp = (struct dmap *) mp->data;
1083
1084        /* try to allocate the blocks immediately following the
1085         * current allocation.
1086         */
1087        rc = dbAllocNext(bmp, dp, extblkno, (int) addnblocks);
1088
1089        IREAD_UNLOCK(ipbmap);
1090
1091        /* were we successful ? */
1092        if (rc == 0)
1093                write_metapage(mp);
1094        else
1095                /* we were not successful */
1096                release_metapage(mp);
1097
1098
1099        return (rc);
1100}
1101
1102
1103/*
1104 * NAME:        dbAllocNext()
1105 *
1106 * FUNCTION:    attempt to allocate the blocks of the specified block
1107 *              range within a dmap.
1108 *
1109 * PARAMETERS:
1110 *      bmp     -  pointer to bmap descriptor
1111 *      dp      -  pointer to dmap.
1112 *      blkno   -  starting block number of the range.
1113 *      nblocks -  number of contiguous free blocks of the range.
1114 *
1115 * RETURN VALUES:
1116 *      0       - success
1117 *      -ENOSPC - insufficient disk resources
1118 *      -EIO    - i/o error
1119 *
1120 * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1121 */
1122static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
1123                       int nblocks)
1124{
1125        int dbitno, word, rembits, nb, nwords, wbitno, nw;
1126        int l2size;
1127        s8 *leaf;
1128        u32 mask;
1129
1130        if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1131                jfs_error(bmp->db_ipbmap->i_sb,
1132                          "dbAllocNext: Corrupt dmap page");
1133                return -EIO;
1134        }
1135
1136        /* pick up a pointer to the leaves of the dmap tree.
1137         */
1138        leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1139
1140        /* determine the bit number and word within the dmap of the
1141         * starting block.
1142         */
1143        dbitno = blkno & (BPERDMAP - 1);
1144        word = dbitno >> L2DBWORD;
1145
1146        /* check if the specified block range is contained within
1147         * this dmap.
1148         */
1149        if (dbitno + nblocks > BPERDMAP)
1150                return -ENOSPC;
1151
1152        /* check if the starting leaf indicates that anything
1153         * is free.
1154         */
1155        if (leaf[word] == NOFREE)
1156                return -ENOSPC;
1157
1158        /* check the dmaps words corresponding to block range to see
1159         * if the block range is free.  not all bits of the first and
1160         * last words may be contained within the block range.  if this
1161         * is the case, we'll work against those words (i.e. partial first
1162         * and/or last) on an individual basis (a single pass) and examine
1163         * the actual bits to determine if they are free.  a single pass
1164         * will be used for all dmap words fully contained within the
1165         * specified range.  within this pass, the leaves of the dmap
1166         * tree will be examined to determine if the blocks are free. a
1167         * single leaf may describe the free space of multiple dmap
1168         * words, so we may visit only a subset of the actual leaves
1169         * corresponding to the dmap words of the block range.
1170         */
1171        for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
1172                /* determine the bit number within the word and
1173                 * the number of bits within the word.
1174                 */
1175                wbitno = dbitno & (DBWORD - 1);
1176                nb = min(rembits, DBWORD - wbitno);
1177
1178                /* check if only part of the word is to be examined.
1179                 */
1180                if (nb < DBWORD) {
1181                        /* check if the bits are free.
1182                         */
1183                        mask = (ONES << (DBWORD - nb) >> wbitno);
1184                        if ((mask & ~le32_to_cpu(dp->wmap[word])) != mask)
1185                                return -ENOSPC;
1186
1187                        word += 1;
1188                } else {
1189                        /* one or more dmap words are fully contained
1190                         * within the block range.  determine how many
1191                         * words and how many bits.
1192                         */
1193                        nwords = rembits >> L2DBWORD;
1194                        nb = nwords << L2DBWORD;
1195
1196                        /* now examine the appropriate leaves to determine
1197                         * if the blocks are free.
1198                         */
1199                        while (nwords > 0) {
1200                                /* does the leaf describe any free space ?
1201                                 */
1202                                if (leaf[word] < BUDMIN)
1203                                        return -ENOSPC;
1204
1205                                /* determine the l2 number of bits provided
1206                                 * by this leaf.
1207                                 */
1208                                l2size =
1209                                    min((int)leaf[word], NLSTOL2BSZ(nwords));
1210
1211                                /* determine how many words were handled.
1212                                 */
1213                                nw = BUDSIZE(l2size, BUDMIN);
1214
1215                                nwords -= nw;
1216                                word += nw;
1217                        }
1218                }
1219        }
1220
1221        /* allocate the blocks.
1222         */
1223        return (dbAllocDmap(bmp, dp, blkno, nblocks));
1224}
1225
1226
1227/*
1228 * NAME:        dbAllocNear()
1229 *
1230 * FUNCTION:    attempt to allocate a number of contiguous free blocks near
1231 *              a specified block (hint) within a dmap.
1232 *
1233 *              starting with the dmap leaf that covers the hint, we'll
1234 *              check the next four contiguous leaves for sufficient free
1235 *              space.  if sufficient free space is found, we'll allocate
1236 *              the desired free space.
1237 *
1238 * PARAMETERS:
1239 *      bmp     -  pointer to bmap descriptor
1240 *      dp      -  pointer to dmap.
1241 *      blkno   -  block number to allocate near.
1242 *      nblocks -  actual number of contiguous free blocks desired.
1243 *      l2nb    -  log2 number of contiguous free blocks desired.
1244 *      results -  on successful return, set to the starting block number
1245 *                 of the newly allocated range.
1246 *
1247 * RETURN VALUES:
1248 *      0       - success
1249 *      -ENOSPC - insufficient disk resources
1250 *      -EIO    - i/o error
1251 *
1252 * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1253 */
1254static int
1255dbAllocNear(struct bmap * bmp,
1256            struct dmap * dp, s64 blkno, int nblocks, int l2nb, s64 * results)
1257{
1258        int word, lword, rc;
1259        s8 *leaf;
1260
1261        if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1262                jfs_error(bmp->db_ipbmap->i_sb,
1263                          "dbAllocNear: Corrupt dmap page");
1264                return -EIO;
1265        }
1266
1267        leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1268
1269        /* determine the word within the dmap that holds the hint
1270         * (i.e. blkno).  also, determine the last word in the dmap
1271         * that we'll include in our examination.
1272         */
1273        word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
1274        lword = min(word + 4, LPERDMAP);
1275
1276        /* examine the leaves for sufficient free space.
1277         */
1278        for (; word < lword; word++) {
1279                /* does the leaf describe sufficient free space ?
1280                 */
1281                if (leaf[word] < l2nb)
1282                        continue;
1283
1284                /* determine the block number within the file system
1285                 * of the first block described by this dmap word.
1286                 */
1287                blkno = le64_to_cpu(dp->start) + (word << L2DBWORD);
1288
1289                /* if not all bits of the dmap word are free, get the
1290                 * starting bit number within the dmap word of the required
1291                 * string of free bits and adjust the block number with the
1292                 * value.
1293                 */
1294                if (leaf[word] < BUDMIN)
1295                        blkno +=
1296                            dbFindBits(le32_to_cpu(dp->wmap[word]), l2nb);
1297
1298                /* allocate the blocks.
1299                 */
1300                if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1301                        *results = blkno;
1302
1303                return (rc);
1304        }
1305
1306        return -ENOSPC;
1307}
1308
1309
1310/*
1311 * NAME:        dbAllocAG()
1312 *
1313 * FUNCTION:    attempt to allocate the specified number of contiguous
1314 *              free blocks within the specified allocation group.
1315 *
1316 *              unless the allocation group size is equal to the number
1317 *              of blocks per dmap, the dmap control pages will be used to
1318 *              find the required free space, if available.  we start the
1319 *              search at the highest dmap control page level which
1320 *              distinctly describes the allocation group's free space
1321 *              (i.e. the highest level at which the allocation group's
1322 *              free space is not mixed in with that of any other group).
1323 *              in addition, we start the search within this level at a
1324 *              height of the dmapctl dmtree at which the nodes distinctly
1325 *              describe the allocation group's free space.  at this height,
1326 *              the allocation group's free space may be represented by 1
1327 *              or two sub-trees, depending on the allocation group size.
1328 *              we search the top nodes of these subtrees left to right for
1329 *              sufficient free space.  if sufficient free space is found,
1330 *              the subtree is searched to find the leftmost leaf that
1331 *              has free space.  once we have made it to the leaf, we
1332 *              move the search to the next lower level dmap control page
1333 *              corresponding to this leaf.  we continue down the dmap control
1334 *              pages until we find the dmap that contains or starts the
1335 *              sufficient free space and we allocate at this dmap.
1336 *
1337 *              if the allocation group size is equal to the dmap size,
1338 *              we'll start at the dmap corresponding to the allocation
1339 *              group and attempt the allocation at this level.
1340 *
1341 *              the dmap control page search is also not performed if the
1342 *              allocation group is completely free and we go to the first
1343 *              dmap of the allocation group to do the allocation.  this is
1344 *              done because the allocation group may be part (not the first
1345 *              part) of a larger binary buddy system, causing the dmap
1346 *              control pages to indicate no free space (NOFREE) within
1347 *              the allocation group.
1348 *
1349 * PARAMETERS:
1350 *      bmp     -  pointer to bmap descriptor
1351 *      agno    - allocation group number.
1352 *      nblocks -  actual number of contiguous free blocks desired.
1353 *      l2nb    -  log2 number of contiguous free blocks desired.
1354 *      results -  on successful return, set to the starting block number
1355 *                 of the newly allocated range.
1356 *
1357 * RETURN VALUES:
1358 *      0       - success
1359 *      -ENOSPC - insufficient disk resources
1360 *      -EIO    - i/o error
1361 *
1362 * note: IWRITE_LOCK(ipmap) held on entry/exit;
1363 */
1364static int
1365dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
1366{
1367        struct metapage *mp;
1368        struct dmapctl *dcp;
1369        int rc, ti, i, k, m, n, agperlev;
1370        s64 blkno, lblkno;
1371        int budmin;
1372
1373        /* allocation request should not be for more than the
1374         * allocation group size.
1375         */
1376        if (l2nb > bmp->db_agl2size) {
1377                jfs_error(bmp->db_ipbmap->i_sb,
1378                          "dbAllocAG: allocation request is larger than the "
1379                          "allocation group size");
1380                return -EIO;
1381        }
1382
1383        /* determine the starting block number of the allocation
1384         * group.
1385         */
1386        blkno = (s64) agno << bmp->db_agl2size;
1387
1388        /* check if the allocation group size is the minimum allocation
1389         * group size or if the allocation group is completely free. if
1390         * the allocation group size is the minimum size of BPERDMAP (i.e.
1391         * 1 dmap), there is no need to search the dmap control page (below)
1392         * that fully describes the allocation group since the allocation
1393         * group is already fully described by a dmap.  in this case, we
1394         * just call dbAllocCtl() to search the dmap tree and allocate the
1395         * required space if available.
1396         *
1397         * if the allocation group is completely free, dbAllocCtl() is
1398         * also called to allocate the required space.  this is done for
1399         * two reasons.  first, it makes no sense searching the dmap control
1400         * pages for free space when we know that free space exists.  second,
1401         * the dmap control pages may indicate that the allocation group
1402         * has no free space if the allocation group is part (not the first
1403         * part) of a larger binary buddy system.
1404         */
1405        if (bmp->db_agsize == BPERDMAP
1406            || bmp->db_agfree[agno] == bmp->db_agsize) {
1407                rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1408                if ((rc == -ENOSPC) &&
1409                    (bmp->db_agfree[agno] == bmp->db_agsize)) {
1410                        printk(KERN_ERR "blkno = %Lx, blocks = %Lx\n",
1411                               (unsigned long long) blkno,
1412                               (unsigned long long) nblocks);
1413                        jfs_error(bmp->db_ipbmap->i_sb,
1414                                  "dbAllocAG: dbAllocCtl failed in free AG");
1415                }
1416                return (rc);
1417        }
1418
1419        /* the buffer for the dmap control page that fully describes the
1420         * allocation group.
1421         */
1422        lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, bmp->db_aglevel);
1423        mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1424        if (mp == NULL)
1425                return -EIO;
1426        dcp = (struct dmapctl *) mp->data;
1427        budmin = dcp->budmin;
1428
1429        if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1430                jfs_error(bmp->db_ipbmap->i_sb,
1431                          "dbAllocAG: Corrupt dmapctl page");
1432                release_metapage(mp);
1433                return -EIO;
1434        }
1435
1436        /* search the subtree(s) of the dmap control page that describes
1437         * the allocation group, looking for sufficient free space.  to begin,
1438         * determine how many allocation groups are represented in a dmap
1439         * control page at the control page level (i.e. L0, L1, L2) that
1440         * fully describes an allocation group. next, determine the starting
1441         * tree index of this allocation group within the control page.
1442         */
1443        agperlev =
1444            (1 << (L2LPERCTL - (bmp->db_agheight << 1))) / bmp->db_agwidth;
1445        ti = bmp->db_agstart + bmp->db_agwidth * (agno & (agperlev - 1));
1446
1447        /* dmap control page trees fan-out by 4 and a single allocation
1448         * group may be described by 1 or 2 subtrees within the ag level
1449         * dmap control page, depending upon the ag size. examine the ag's
1450         * subtrees for sufficient free space, starting with the leftmost
1451         * subtree.
1452         */
1453        for (i = 0; i < bmp->db_agwidth; i++, ti++) {
1454                /* is there sufficient free space ?
1455                 */
1456                if (l2nb > dcp->stree[ti])
1457                        continue;
1458
1459                /* sufficient free space found in a subtree. now search down
1460                 * the subtree to find the leftmost leaf that describes this
1461                 * free space.
1462                 */
1463                for (k = bmp->db_agheight; k > 0; k--) {
1464                        for (n = 0, m = (ti << 2) + 1; n < 4; n++) {
1465                                if (l2nb <= dcp->stree[m + n]) {
1466                                        ti = m + n;
1467                                        break;
1468                                }
1469                        }
1470                        if (n == 4) {
1471                                jfs_error(bmp->db_ipbmap->i_sb,
1472                                          "dbAllocAG: failed descending stree");
1473                                release_metapage(mp);
1474                                return -EIO;
1475                        }
1476                }
1477
1478                /* determine the block number within the file system
1479                 * that corresponds to this leaf.
1480                 */
1481                if (bmp->db_aglevel == 2)
1482                        blkno = 0;
1483                else if (bmp->db_aglevel == 1)
1484                        blkno &= ~(MAXL1SIZE - 1);
1485                else            /* bmp->db_aglevel == 0 */
1486                        blkno &= ~(MAXL0SIZE - 1);
1487
1488                blkno +=
1489                    ((s64) (ti - le32_to_cpu(dcp->leafidx))) << budmin;
1490
1491                /* release the buffer in preparation for going down
1492                 * the next level of dmap control pages.
1493                 */
1494                release_metapage(mp);
1495
1496                /* check if we need to continue to search down the lower
1497                 * level dmap control pages.  we need to if the number of
1498                 * blocks required is less than maximum number of blocks
1499                 * described at the next lower level.
1500                 */
1501                if (l2nb < budmin) {
1502
1503                        /* search the lower level dmap control pages to get
1504                         * the starting block number of the dmap that
1505                         * contains or starts off the free space.
1506                         */
1507                        if ((rc =
1508                             dbFindCtl(bmp, l2nb, bmp->db_aglevel - 1,
1509                                       &blkno))) {
1510                                if (rc == -ENOSPC) {
1511                                        jfs_error(bmp->db_ipbmap->i_sb,
1512                                                  "dbAllocAG: control page "
1513                                                  "inconsistent");
1514                                        return -EIO;
1515                                }
1516                                return (rc);
1517                        }
1518                }
1519
1520                /* allocate the blocks.
1521                 */
1522                rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1523                if (rc == -ENOSPC) {
1524                        jfs_error(bmp->db_ipbmap->i_sb,
1525                                  "dbAllocAG: unable to allocate blocks");
1526                        rc = -EIO;
1527                }
1528                return (rc);
1529        }
1530
1531        /* no space in the allocation group.  release the buffer and
1532         * return -ENOSPC.
1533         */
1534        release_metapage(mp);
1535
1536        return -ENOSPC;
1537}
1538
1539
1540/*
1541 * NAME:        dbAllocAny()
1542 *
1543 * FUNCTION:    attempt to allocate the specified number of contiguous
1544 *              free blocks anywhere in the file system.
1545 *
1546 *              dbAllocAny() attempts to find the sufficient free space by
1547 *              searching down the dmap control pages, starting with the
1548 *              highest level (i.e. L0, L1, L2) control page.  if free space
1549 *              large enough to satisfy the desired free space is found, the
1550 *              desired free space is allocated.
1551 *
1552 * PARAMETERS:
1553 *      bmp     -  pointer to bmap descriptor
1554 *      nblocks  -  actual number of contiguous free blocks desired.
1555 *      l2nb     -  log2 number of contiguous free blocks desired.
1556 *      results -  on successful return, set to the starting block number
1557 *                 of the newly allocated range.
1558 *
1559 * RETURN VALUES:
1560 *      0       - success
1561 *      -ENOSPC - insufficient disk resources
1562 *      -EIO    - i/o error
1563 *
1564 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1565 */
1566static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results)
1567{
1568        int rc;
1569        s64 blkno = 0;
1570
1571        /* starting with the top level dmap control page, search
1572         * down the dmap control levels for sufficient free space.
1573         * if free space is found, dbFindCtl() returns the starting
1574         * block number of the dmap that contains or starts off the
1575         * range of free space.
1576         */
1577        if ((rc = dbFindCtl(bmp, l2nb, bmp->db_maxlevel, &blkno)))
1578                return (rc);
1579
1580        /* allocate the blocks.
1581         */
1582        rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1583        if (rc == -ENOSPC) {
1584                jfs_error(bmp->db_ipbmap->i_sb,
1585                          "dbAllocAny: unable to allocate blocks");
1586                return -EIO;
1587        }
1588        return (rc);
1589}
1590
1591
1592/*
1593 * NAME:        dbFindCtl()
1594 *
1595 * FUNCTION:    starting at a specified dmap control page level and block
1596 *              number, search down the dmap control levels for a range of
1597 *              contiguous free blocks large enough to satisfy an allocation
1598 *              request for the specified number of free blocks.
1599 *
1600 *              if sufficient contiguous free blocks are found, this routine
1601 *              returns the starting block number within a dmap page that
1602 *              contains or starts a range of contiqious free blocks that
1603 *              is sufficient in size.
1604 *
1605 * PARAMETERS:
1606 *      bmp     -  pointer to bmap descriptor
1607 *      level   -  starting dmap control page level.
1608 *      l2nb    -  log2 number of contiguous free blocks desired.
1609 *      *blkno  -  on entry, starting block number for conducting the search.
1610 *                 on successful return, the first block within a dmap page
1611 *                 that contains or starts a range of contiguous free blocks.
1612 *
1613 * RETURN VALUES:
1614 *      0       - success
1615 *      -ENOSPC - insufficient disk resources
1616 *      -EIO    - i/o error
1617 *
1618 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1619 */
1620static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno)
1621{
1622        int rc, leafidx, lev;
1623        s64 b, lblkno;
1624        struct dmapctl *dcp;
1625        int budmin;
1626        struct metapage *mp;
1627
1628        /* starting at the specified dmap control page level and block
1629         * number, search down the dmap control levels for the starting
1630         * block number of a dmap page that contains or starts off
1631         * sufficient free blocks.
1632         */
1633        for (lev = level, b = *blkno; lev >= 0; lev--) {
1634                /* get the buffer of the dmap control page for the block
1635                 * number and level (i.e. L0, L1, L2).
1636                 */
1637                lblkno = BLKTOCTL(b, bmp->db_l2nbperpage, lev);
1638                mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1639                if (mp == NULL)
1640                        return -EIO;
1641                dcp = (struct dmapctl *) mp->data;
1642                budmin = dcp->budmin;
1643
1644                if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1645                        jfs_error(bmp->db_ipbmap->i_sb,
1646                                  "dbFindCtl: Corrupt dmapctl page");
1647                        release_metapage(mp);
1648                        return -EIO;
1649                }
1650
1651                /* search the tree within the dmap control page for
1652                 * sufficient free space.  if sufficient free space is found,
1653                 * dbFindLeaf() returns the index of the leaf at which
1654                 * free space was found.
1655                 */
1656                rc = dbFindLeaf((dmtree_t *) dcp, l2nb, &leafidx);
1657
1658                /* release the buffer.
1659                 */
1660                release_metapage(mp);
1661
1662                /* space found ?
1663                 */
1664                if (rc) {
1665                        if (lev != level) {
1666                                jfs_error(bmp->db_ipbmap->i_sb,
1667                                          "dbFindCtl: dmap inconsistent");
1668                                return -EIO;
1669                        }
1670                        return -ENOSPC;
1671                }
1672
1673                /* adjust the block number to reflect the location within
1674                 * the dmap control page (i.e. the leaf) at which free
1675                 * space was found.
1676                 */
1677                b += (((s64) leafidx) << budmin);
1678
1679                /* we stop the search at this dmap control page level if
1680                 * the number of blocks required is greater than or equal
1681                 * to the maximum number of blocks described at the next
1682                 * (lower) level.
1683                 */
1684                if (l2nb >= budmin)
1685                        break;
1686        }
1687
1688        *blkno = b;
1689        return (0);
1690}
1691
1692
1693/*
1694 * NAME:        dbAllocCtl()
1695 *
1696 * FUNCTION:    attempt to allocate a specified number of contiguous
1697 *              blocks starting within a specific dmap.
1698 *
1699 *              this routine is called by higher level routines that search
1700 *              the dmap control pages above the actual dmaps for contiguous
1701 *              free space.  the result of successful searches by these
1702 *              routines are the starting block numbers within dmaps, with
1703 *              the dmaps themselves containing the desired contiguous free
1704 *              space or starting a contiguous free space of desired size
1705 *              that is made up of the blocks of one or more dmaps. these
1706 *              calls should not fail due to insufficent resources.
1707 *
1708 *              this routine is called in some cases where it is not known
1709 *              whether it will fail due to insufficient resources.  more
1710 *              specifically, this occurs when allocating from an allocation
1711 *              group whose size is equal to the number of blocks per dmap.
1712 *              in this case, the dmap control pages are not examined prior
1713 *              to calling this routine (to save pathlength) and the call
1714 *              might fail.
1715 *
1716 *              for a request size that fits within a dmap, this routine relies
1717 *              upon the dmap's dmtree to find the requested contiguous free
1718 *              space.  for request sizes that are larger than a dmap, the
1719 *              requested free space will start at the first block of the
1720 *              first dmap (i.e. blkno).
1721 *
1722 * PARAMETERS:
1723 *      bmp     -  pointer to bmap descriptor
1724 *      nblocks  -  actual number of contiguous free blocks to allocate.
1725 *      l2nb     -  log2 number of contiguous free blocks to allocate.
1726 *      blkno    -  starting block number of the dmap to start the allocation
1727 *                  from.
1728 *      results -  on successful return, set to the starting block number
1729 *                 of the newly allocated range.
1730 *
1731 * RETURN VALUES:
1732 *      0       - success
1733 *      -ENOSPC - insufficient disk resources
1734 *      -EIO    - i/o error
1735 *
1736 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1737 */
1738static int
1739dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno, s64 * results)
1740{
1741        int rc, nb;
1742        s64 b, lblkno, n;
1743        struct metapage *mp;
1744        struct dmap *dp;
1745
1746        /* check if the allocation request is confined to a single dmap.
1747         */
1748        if (l2nb <= L2BPERDMAP) {
1749                /* get the buffer for the dmap.
1750                 */
1751                lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
1752                mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1753                if (mp == NULL)
1754                        return -EIO;
1755                dp = (struct dmap *) mp->data;
1756
1757                /* try to allocate the blocks.
1758                 */
1759                rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results);
1760                if (rc == 0)
1761                        mark_metapage_dirty(mp);
1762
1763                release_metapage(mp);
1764
1765                return (rc);
1766        }
1767
1768        /* allocation request involving multiple dmaps. it must start on
1769         * a dmap boundary.
1770         */
1771        assert((blkno & (BPERDMAP - 1)) == 0);
1772
1773        /* allocate the blocks dmap by dmap.
1774         */
1775        for (n = nblocks, b = blkno; n > 0; n -= nb, b += nb) {
1776                /* get the buffer for the dmap.
1777                 */
1778                lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1779                mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1780                if (mp == NULL) {
1781                        rc = -EIO;
1782                        goto backout;
1783                }
1784                dp = (struct dmap *) mp->data;
1785
1786                /* the dmap better be all free.
1787                 */
1788                if (dp->tree.stree[ROOT] != L2BPERDMAP) {
1789                        release_metapage(mp);
1790                        jfs_error(bmp->db_ipbmap->i_sb,
1791                                  "dbAllocCtl: the dmap is not all free");
1792                        rc = -EIO;
1793                        goto backout;
1794                }
1795
1796                /* determine how many blocks to allocate from this dmap.
1797                 */
1798                nb = min(n, (s64)BPERDMAP);
1799
1800                /* allocate the blocks from the dmap.
1801                 */
1802                if ((rc = dbAllocDmap(bmp, dp, b, nb))) {
1803                        release_metapage(mp);
1804                        goto backout;
1805                }
1806
1807                /* write the buffer.
1808                 */
1809                write_metapage(mp);
1810        }
1811
1812        /* set the results (starting block number) and return.
1813         */
1814        *results = blkno;
1815        return (0);
1816
1817        /* something failed in handling an allocation request involving
1818         * multiple dmaps.  we'll try to clean up by backing out any
1819         * allocation that has already happened for this request.  if
1820         * we fail in backing out the allocation, we'll mark the file
1821         * system to indicate that blocks have been leaked.
1822         */
1823      backout:
1824
1825        /* try to backout the allocations dmap by dmap.
1826         */
1827        for (n = nblocks - n, b = blkno; n > 0;
1828             n -= BPERDMAP, b += BPERDMAP) {
1829                /* get the buffer for this dmap.
1830                 */
1831                lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1832                mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1833                if (mp == NULL) {
1834                        /* could not back out.  mark the file system
1835                         * to indicate that we have leaked blocks.
1836                         */
1837                        jfs_error(bmp->db_ipbmap->i_sb,
1838                                  "dbAllocCtl: I/O Error: Block Leakage.");
1839                        continue;
1840                }
1841                dp = (struct dmap *) mp->data;
1842
1843                /* free the blocks is this dmap.
1844                 */
1845                if (dbFreeDmap(bmp, dp, b, BPERDMAP)) {
1846                        /* could not back out.  mark the file system
1847                         * to indicate that we have leaked blocks.
1848                         */
1849                        release_metapage(mp);
1850                        jfs_error(bmp->db_ipbmap->i_sb,
1851                                  "dbAllocCtl: Block Leakage.");
1852                        continue;
1853                }
1854
1855                /* write the buffer.
1856                 */
1857                write_metapage(mp);
1858        }
1859
1860        return (rc);
1861}
1862
1863
1864/*
1865 * NAME:        dbAllocDmapLev()
1866 *
1867 * FUNCTION:    attempt to allocate a specified number of contiguous blocks
1868 *              from a specified dmap.
1869 *
1870 *              this routine checks if the contiguous blocks are available.
1871 *              if so, nblocks of blocks are allocated; otherwise, ENOSPC is
1872 *              returned.
1873 *
1874 * PARAMETERS:
1875 *      mp      -  pointer to bmap descriptor
1876 *      dp      -  pointer to dmap to attempt to allocate blocks from.
1877 *      l2nb    -  log2 number of contiguous block desired.
1878 *      nblocks -  actual number of contiguous block desired.
1879 *      results -  on successful return, set to the starting block number
1880 *                 of the newly allocated range.
1881 *
1882 * RETURN VALUES:
1883 *      0       - success
1884 *      -ENOSPC - insufficient disk resources
1885 *      -EIO    - i/o error
1886 *
1887 * serialization: IREAD_LOCK(ipbmap), e.g., from dbAlloc(), or
1888 *      IWRITE_LOCK(ipbmap), e.g., dbAllocCtl(), held on entry/exit;
1889 */
1890static int
1891dbAllocDmapLev(struct bmap * bmp,
1892               struct dmap * dp, int nblocks, int l2nb, s64 * results)
1893{
1894        s64 blkno;
1895        int leafidx, rc;
1896
1897        /* can't be more than a dmaps worth of blocks */
1898        assert(l2nb <= L2BPERDMAP);
1899
1900        /* search the tree within the dmap page for sufficient
1901         * free space.  if sufficient free space is found, dbFindLeaf()
1902         * returns the index of the leaf at which free space was found.
1903         */
1904        if (dbFindLeaf((dmtree_t *) & dp->tree, l2nb, &leafidx))
1905                return -ENOSPC;
1906
1907        /* determine the block number within the file system corresponding
1908         * to the leaf at which free space was found.
1909         */
1910        blkno = le64_to_cpu(dp->start) + (leafidx << L2DBWORD);
1911
1912        /* if not all bits of the dmap word are free, get the starting
1913         * bit number within the dmap word of the required string of free
1914         * bits and adjust the block number with this value.
1915         */
1916        if (dp->tree.stree[leafidx + LEAFIND] < BUDMIN)
1917                blkno += dbFindBits(le32_to_cpu(dp->wmap[leafidx]), l2nb);
1918
1919        /* allocate the blocks */
1920        if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1921                *results = blkno;
1922
1923        return (rc);
1924}
1925
1926
1927/*
1928 * NAME:        dbAllocDmap()
1929 *
1930 * FUNCTION:    adjust the disk allocation map to reflect the allocation
1931 *              of a specified block range within a dmap.
1932 *
1933 *              this routine allocates the specified blocks from the dmap
1934 *              through a call to dbAllocBits(). if the allocation of the
1935 *              block range causes the maximum string of free blocks within
1936 *              the dmap to change (i.e. the value of the root of the dmap's
1937 *              dmtree), this routine will cause this change to be reflected
1938 *              up through the appropriate levels of the dmap control pages
1939 *              by a call to dbAdjCtl() for the L0 dmap control page that
1940 *              covers this dmap.
1941 *
1942 * PARAMETERS:
1943 *      bmp     -  pointer to bmap descriptor
1944 *      dp      -  pointer to dmap to allocate the block range from.
1945 *      blkno   -  starting block number of the block to be allocated.
1946 *      nblocks -  number of blocks to be allocated.
1947 *
1948 * RETURN VALUES:
1949 *      0       - success
1950 *      -EIO    - i/o error
1951 *
1952 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
1953 */
1954static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
1955                       int nblocks)
1956{
1957        s8 oldroot;
1958        int rc;
1959
1960        /* save the current value of the root (i.e. maximum free string)
1961         * of the dmap tree.
1962         */
1963        oldroot = dp->tree.stree[ROOT];
1964
1965        /* allocate the specified (blocks) bits */
1966        dbAllocBits(bmp, dp, blkno, nblocks);
1967
1968        /* if the root has not changed, done. */
1969        if (dp->tree.stree[ROOT] == oldroot)
1970                return (0);
1971
1972        /* root changed. bubble the change up to the dmap control pages.
1973         * if the adjustment of the upper level control pages fails,
1974         * backout the bit allocation (thus making everything consistent).
1975         */
1976        if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 1, 0)))
1977                dbFreeBits(bmp, dp, blkno, nblocks);
1978
1979        return (rc);
1980}
1981
1982
1983/*
1984 * NAME:        dbFreeDmap()
1985 *
1986 * FUNCTION:    adjust the disk allocation map to reflect the allocation
1987 *              of a specified block range within a dmap.
1988 *
1989 *              this routine frees the specified blocks from the dmap through
1990 *              a call to dbFreeBits(). if the deallocation of the block range
1991 *              causes the maximum string of free blocks within the dmap to
1992 *              change (i.e. the value of the root of the dmap's dmtree), this
1993 *              routine will cause this change to be reflected up through the
1994 *              appropriate levels of the dmap control pages by a call to
1995 *              dbAdjCtl() for the L0 dmap control page that covers this dmap.
1996 *
1997 * PARAMETERS:
1998 *      bmp     -  pointer to bmap descriptor
1999 *      dp      -  pointer to dmap to free the block range from.
2000 *      blkno   -  starting block number of the block to be freed.
2001 *      nblocks -  number of blocks to be freed.
2002 *
2003 * RETURN VALUES:
2004 *      0       - success
2005 *      -EIO    - i/o error
2006 *
2007 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2008 */
2009static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2010                      int nblocks)
2011{
2012        s8 oldroot;
2013        int rc = 0, word;
2014
2015        /* save the current value of the root (i.e. maximum free string)
2016         * of the dmap tree.
2017         */
2018        oldroot = dp->tree.stree[ROOT];
2019
2020        /* free the specified (blocks) bits */
2021        rc = dbFreeBits(bmp, dp, blkno, nblocks);
2022
2023        /* if error or the root has not changed, done. */
2024        if (rc || (dp->tree.stree[ROOT] == oldroot))
2025                return (rc);
2026
2027        /* root changed. bubble the change up to the dmap control pages.
2028         * if the adjustment of the upper level control pages fails,
2029         * backout the deallocation.
2030         */
2031        if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 0, 0))) {
2032                word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
2033
2034                /* as part of backing out the deallocation, we will have
2035                 * to back split the dmap tree if the deallocation caused
2036                 * the freed blocks to become part of a larger binary buddy
2037                 * system.
2038                 */
2039                if (dp->tree.stree[word] == NOFREE)
2040                        dbBackSplit((dmtree_t *) & dp->tree, word);
2041
2042                dbAllocBits(bmp, dp, blkno, nblocks);
2043        }
2044
2045        return (rc);
2046}
2047
2048
2049/*
2050 * NAME:        dbAllocBits()
2051 *
2052 * FUNCTION:    allocate a specified block range from a dmap.
2053 *
2054 *              this routine updates the dmap to reflect the working
2055 *              state allocation of the specified block range. it directly
2056 *              updates the bits of the working map and causes the adjustment
2057 *              of the binary buddy system described by the dmap's dmtree
2058 *              leaves to reflect the bits allocated.  it also causes the
2059 *              dmap's dmtree, as a whole, to reflect the allocated range.
2060 *
2061 * PARAMETERS:
2062 *      bmp     -  pointer to bmap descriptor
2063 *      dp      -  pointer to dmap to allocate bits from.
2064 *      blkno   -  starting block number of the bits to be allocated.
2065 *      nblocks -  number of bits to be allocated.
2066 *
2067 * RETURN VALUES: none
2068 *
2069 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2070 */
2071static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2072                        int nblocks)
2073{
2074        int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2075        dmtree_t *tp = (dmtree_t *) & dp->tree;
2076        int size;
2077        s8 *leaf;
2078
2079        /* pick up a pointer to the leaves of the dmap tree */
2080        leaf = dp->tree.stree + LEAFIND;
2081
2082        /* determine the bit number and word within the dmap of the
2083         * starting block.
2084         */
2085        dbitno = blkno & (BPERDMAP - 1);
2086        word = dbitno >> L2DBWORD;
2087
2088        /* block range better be within the dmap */
2089        assert(dbitno + nblocks <= BPERDMAP);
2090
2091        /* allocate the bits of the dmap's words corresponding to the block
2092         * range. not all bits of the first and last words may be contained
2093         * within the block range.  if this is the case, we'll work against
2094         * those words (i.e. partial first and/or last) on an individual basis
2095         * (a single pass), allocating the bits of interest by hand and
2096         * updating the leaf corresponding to the dmap word. a single pass
2097         * will be used for all dmap words fully contained within the
2098         * specified range.  within this pass, the bits of all fully contained
2099         * dmap words will be marked as free in a single shot and the leaves
2100         * will be updated. a single leaf may describe the free space of
2101         * multiple dmap words, so we may update only a subset of the actual
2102         * leaves corresponding to the dmap words of the block range.
2103         */
2104        for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2105                /* determine the bit number within the word and
2106                 * the number of bits within the word.
2107                 */
2108                wbitno = dbitno & (DBWORD - 1);
2109                nb = min(rembits, DBWORD - wbitno);
2110
2111                /* check if only part of a word is to be allocated.
2112                 */
2113                if (nb < DBWORD) {
2114                        /* allocate (set to 1) the appropriate bits within
2115                         * this dmap word.
2116                         */
2117                        dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
2118                                                      >> wbitno);
2119
2120                        /* update the leaf for this dmap word. in addition
2121                         * to setting the leaf value to the binary buddy max
2122                         * of the updated dmap word, dbSplit() will split
2123                         * the binary system of the leaves if need be.
2124                         */
2125                        dbSplit(tp, word, BUDMIN,
2126                                dbMaxBud((u8 *) & dp->wmap[word]));
2127
2128                        word += 1;
2129                } else {
2130                        /* one or more dmap words are fully contained
2131                         * within the block range.  determine how many
2132                         * words and allocate (set to 1) the bits of these
2133                         * words.
2134                         */
2135                        nwords = rembits >> L2DBWORD;
2136                        memset(&dp->wmap[word], (int) ONES, nwords * 4);
2137
2138                        /* determine how many bits.
2139                         */
2140                        nb = nwords << L2DBWORD;
2141
2142                        /* now update the appropriate leaves to reflect
2143                         * the allocated words.
2144                         */
2145                        for (; nwords > 0; nwords -= nw) {
2146                                if (leaf[word] < BUDMIN) {
2147                                        jfs_error(bmp->db_ipbmap->i_sb,
2148                                                  "dbAllocBits: leaf page "
2149                                                  "corrupt");
2150                                        break;
2151                                }
2152
2153                                /* determine what the leaf value should be
2154                                 * updated to as the minimum of the l2 number
2155                                 * of bits being allocated and the l2 number
2156                                 * of bits currently described by this leaf.
2157                                 */
2158                                size = min((int)leaf[word], NLSTOL2BSZ(nwords));
2159
2160                                /* update the leaf to reflect the allocation.
2161                                 * in addition to setting the leaf value to
2162                                 * NOFREE, dbSplit() will split the binary
2163                                 * system of the leaves to reflect the current
2164                                 * allocation (size).
2165                                 */
2166                                dbSplit(tp, word, size, NOFREE);
2167
2168                                /* get the number of dmap words handled */
2169                                nw = BUDSIZE(size, BUDMIN);
2170                                word += nw;
2171                        }
2172                }
2173        }
2174
2175        /* update the free count for this dmap */
2176        le32_add_cpu(&dp->nfree, -nblocks);
2177
2178        BMAP_LOCK(bmp);
2179
2180        /* if this allocation group is completely free,
2181         * update the maximum allocation group number if this allocation
2182         * group is the new max.
2183         */
2184        agno = blkno >> bmp->db_agl2size;
2185        if (agno > bmp->db_maxag)
2186                bmp->db_maxag = agno;
2187
2188        /* update the free count for the allocation group and map */
2189        bmp->db_agfree[agno] -= nblocks;
2190        bmp->db_nfree -= nblocks;
2191
2192        BMAP_UNLOCK(bmp);
2193}
2194
2195
2196/*
2197 * NAME:        dbFreeBits()
2198 *
2199 * FUNCTION:    free a specified block range from a dmap.
2200 *
2201 *              this routine updates the dmap to reflect the working
2202 *              state allocation of the specified block range. it directly
2203 *              updates the bits of the working map and causes the adjustment
2204 *              of the binary buddy system described by the dmap's dmtree
2205 *              leaves to reflect the bits freed.  it also causes the dmap's
2206 *              dmtree, as a whole, to reflect the deallocated range.
2207 *
2208 * PARAMETERS:
2209 *      bmp     -  pointer to bmap descriptor
2210 *      dp      -  pointer to dmap to free bits from.
2211 *      blkno   -  starting block number of the bits to be freed.
2212 *      nblocks -  number of bits to be freed.
2213 *
2214 * RETURN VALUES: 0 for success
2215 *
2216 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2217 */
2218static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2219                       int nblocks)
2220{
2221        int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2222        dmtree_t *tp = (dmtree_t *) & dp->tree;
2223        int rc = 0;
2224        int size;
2225
2226        /* determine the bit number and word within the dmap of the
2227         * starting block.
2228         */
2229        dbitno = blkno & (BPERDMAP - 1);
2230        word = dbitno >> L2DBWORD;
2231
2232        /* block range better be within the dmap.
2233         */
2234        assert(dbitno + nblocks <= BPERDMAP);
2235
2236        /* free the bits of the dmaps words corresponding to the block range.
2237         * not all bits of the first and last words may be contained within
2238         * the block range.  if this is the case, we'll work against those
2239         * words (i.e. partial first and/or last) on an individual basis
2240         * (a single pass), freeing the bits of interest by hand and updating
2241         * the leaf corresponding to the dmap word. a single pass will be used
2242         * for all dmap words fully contained within the specified range.
2243         * within this pass, the bits of all fully contained dmap words will
2244         * be marked as free in a single shot and the leaves will be updated. a
2245         * single leaf may describe the free space of multiple dmap words,
2246         * so we may update only a subset of the actual leaves corresponding
2247         * to the dmap words of the block range.
2248         *
2249         * dbJoin() is used to update leaf values and will join the binary
2250         * buddy system of the leaves if the new leaf values indicate this
2251         * should be done.
2252         */
2253        for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2254                /* determine the bit number within the word and
2255                 * the number of bits within the word.
2256                 */
2257                wbitno = dbitno & (DBWORD - 1);
2258                nb = min(rembits, DBWORD - wbitno);
2259
2260                /* check if only part of a word is to be freed.
2261                 */
2262                if (nb < DBWORD) {
2263                        /* free (zero) the appropriate bits within this
2264                         * dmap word.
2265                         */
2266                        dp->wmap[word] &=
2267                            cpu_to_le32(~(ONES << (DBWORD - nb)
2268                                          >> wbitno));
2269
2270                        /* update the leaf for this dmap word.
2271                         */
2272                        rc = dbJoin(tp, word,
2273                                    dbMaxBud((u8 *) & dp->wmap[word]));
2274                        if (rc)
2275                                return rc;
2276
2277                        word += 1;
2278                } else {
2279                        /* one or more dmap words are fully contained
2280                         * within the block range.  determine how many
2281                         * words and free (zero) the bits of these words.
2282                         */
2283                        nwords = rembits >> L2DBWORD;
2284                        memset(&dp->wmap[word], 0, nwords * 4);
2285
2286                        /* determine how many bits.
2287                         */
2288                        nb = nwords << L2DBWORD;
2289
2290                        /* now update the appropriate leaves to reflect
2291                         * the freed words.
2292                         */
2293                        for (; nwords > 0; nwords -= nw) {
2294                                /* determine what the leaf value should be
2295                                 * updated to as the minimum of the l2 number
2296                                 * of bits being freed and the l2 (max) number
2297                                 * of bits that can be described by this leaf.
2298                                 */
2299                                size =
2300                                    min(LITOL2BSZ
2301                                        (word, L2LPERDMAP, BUDMIN),
2302                                        NLSTOL2BSZ(nwords));
2303
2304                                /* update the leaf.
2305                                 */
2306                                rc = dbJoin(tp, word, size);
2307                                if (rc)
2308                                        return rc;
2309
2310                                /* get the number of dmap words handled.
2311                                 */
2312                                nw = BUDSIZE(size, BUDMIN);
2313                                word += nw;
2314                        }
2315                }
2316        }
2317
2318        /* update the free count for this dmap.
2319         */
2320        le32_add_cpu(&dp->nfree, nblocks);
2321
2322        BMAP_LOCK(bmp);
2323
2324        /* update the free count for the allocation group and
2325         * map.
2326         */
2327        agno = blkno >> bmp->db_agl2size;
2328        bmp->db_nfree += nblocks;
2329        bmp->db_agfree[agno] += nblocks;
2330
2331        /* check if this allocation group is not completely free and
2332         * if it is currently the maximum (rightmost) allocation group.
2333         * if so, establish the new maximum allocation group number by
2334         * searching left for the first allocation group with allocation.
2335         */
2336        if ((bmp->db_agfree[agno] == bmp->db_agsize && agno == bmp->db_maxag) ||
2337            (agno == bmp->db_numag - 1 &&
2338             bmp->db_agfree[agno] == (bmp-> db_mapsize & (BPERDMAP - 1)))) {
2339                while (bmp->db_maxag > 0) {
2340                        bmp->db_maxag -= 1;
2341                        if (bmp->db_agfree[bmp->db_maxag] !=
2342                            bmp->db_agsize)
2343                                break;
2344                }
2345
2346                /* re-establish the allocation group preference if the
2347                 * current preference is right of the maximum allocation
2348                 * group.
2349                 */
2350                if (bmp->db_agpref > bmp->db_maxag)
2351                        bmp->db_agpref = bmp->db_maxag;
2352        }
2353
2354        BMAP_UNLOCK(bmp);
2355
2356        return 0;
2357}
2358
2359
2360/*
2361 * NAME:        dbAdjCtl()
2362 *
2363 * FUNCTION:    adjust a dmap control page at a specified level to reflect
2364 *              the change in a lower level dmap or dmap control page's
2365 *              maximum string of free blocks (i.e. a change in the root
2366 *              of the lower level object's dmtree) due to the allocation
2367 *              or deallocation of a range of blocks with a single dmap.
2368 *
2369 *              on entry, this routine is provided with the new value of
2370 *              the lower level dmap or dmap control page root and the
2371 *              starting block number of the block range whose allocation
2372 *              or deallocation resulted in the root change.  this range
2373 *              is respresented by a single leaf of the current dmapctl
2374 *              and the leaf will be updated with this value, possibly
2375 *              causing a binary buddy system within the leaves to be
2376 *              split or joined.  the update may also cause the dmapctl's
2377 *              dmtree to be updated.
2378 *
2379 *              if the adjustment of the dmap control page, itself, causes its
2380 *              root to change, this change will be bubbled up to the next dmap
2381 *              control level by a recursive call to this routine, specifying
2382 *              the new root value and the next dmap control page level to
2383 *              be adjusted.
2384 * PARAMETERS:
2385 *      bmp     -  pointer to bmap descriptor
2386 *      blkno   -  the first block of a block range within a dmap.  it is
2387 *                 the allocation or deallocation of this block range that
2388 *                 requires the dmap control page to be adjusted.
2389 *      newval  -  the new value of the lower level dmap or dmap control
2390 *                 page root.
2391 *      alloc   -  'true' if adjustment is due to an allocation.
2392 *      level   -  current level of dmap control page (i.e. L0, L1, L2) to
2393 *                 be adjusted.
2394 *
2395 * RETURN VALUES:
2396 *      0       - success
2397 *      -EIO    - i/o error
2398 *
2399 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2400 */
2401static int
2402dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
2403{
2404        struct metapage *mp;
2405        s8 oldroot;
2406        int oldval;
2407        s64 lblkno;
2408        struct dmapctl *dcp;
2409        int rc, leafno, ti;
2410
2411        /* get the buffer for the dmap control page for the specified
2412         * block number and control page level.
2413         */
2414        lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, level);
2415        mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
2416        if (mp == NULL)
2417                return -EIO;
2418        dcp = (struct dmapctl *) mp->data;
2419
2420        if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
2421                jfs_error(bmp->db_ipbmap->i_sb,
2422                          "dbAdjCtl: Corrupt dmapctl page");
2423                release_metapage(mp);
2424                return -EIO;
2425        }
2426
2427        /* determine the leaf number corresponding to the block and
2428         * the index within the dmap control tree.
2429         */
2430        leafno = BLKTOCTLLEAF(blkno, dcp->budmin);
2431        ti = leafno + le32_to_cpu(dcp->leafidx);
2432
2433        /* save the current leaf value and the current root level (i.e.
2434         * maximum l2 free string described by this dmapctl).
2435         */
2436        oldval = dcp->stree[ti];
2437        oldroot = dcp->stree[ROOT];
2438
2439        /* check if this is a control page update for an allocation.
2440         * if so, update the leaf to reflect the new leaf value using
2441         * dbSplit(); otherwise (deallocation), use dbJoin() to update
2442         * the leaf with the new value.  in addition to updating the
2443         * leaf, dbSplit() will also split the binary buddy system of
2444         * the leaves, if required, and bubble new values within the
2445         * dmapctl tree, if required.  similarly, dbJoin() will join
2446         * the binary buddy system of leaves and bubble new values up
2447         * the dmapctl tree as required by the new leaf value.
2448         */
2449        if (alloc) {
2450                /* check if we are in the middle of a binary buddy
2451                 * system.  this happens when we are performing the
2452                 * first allocation out of an allocation group that
2453                 * is part (not the first part) of a larger binary
2454                 * buddy system.  if we are in the middle, back split
2455                 * the system prior to calling dbSplit() which assumes
2456                 * that it is at the front of a binary buddy system.
2457                 */
2458                if (oldval == NOFREE) {
2459                        rc = dbBackSplit((dmtree_t *) dcp, leafno);
2460                        if (rc)
2461                                return rc;
2462                        oldval = dcp->stree[ti];
2463                }
2464                dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval);
2465        } else {
2466                rc = dbJoin((dmtree_t *) dcp, leafno, newval);
2467                if (rc)
2468                        return rc;
2469        }
2470
2471        /* check if the root of the current dmap control page changed due
2472         * to the update and if the current dmap control page is not at
2473         * the current top level (i.e. L0, L1, L2) of the map.  if so (i.e.
2474         * root changed and this is not the top level), call this routine
2475         * again (recursion) for the next higher level of the mapping to
2476         * reflect the change in root for the current dmap control page.
2477         */
2478        if (dcp->stree[ROOT] != oldroot) {
2479                /* are we below the top level of the map.  if so,
2480                 * bubble the root up to the next higher level.
2481                 */
2482                if (level < bmp->db_maxlevel) {
2483                        /* bubble up the new root of this dmap control page to
2484                         * the next level.
2485                         */
2486                        if ((rc =
2487                             dbAdjCtl(bmp, blkno, dcp->stree[ROOT], alloc,
2488                                      level + 1))) {
2489                                /* something went wrong in bubbling up the new
2490                                 * root value, so backout the changes to the
2491                                 * current dmap control page.
2492                                 */
2493                                if (alloc) {
2494                                        dbJoin((dmtree_t *) dcp, leafno,
2495                                               oldval);
2496                                } else {
2497                                        /* the dbJoin() above might have
2498                                         * caused a larger binary buddy system
2499                                         * to form and we may now be in the
2500                                         * middle of it.  if this is the case,
2501                                         * back split the buddies.
2502                                         */
2503                                        if (dcp->stree[ti] == NOFREE)
2504                                                dbBackSplit((dmtree_t *)
2505                                                            dcp, leafno);
2506                                        dbSplit((dmtree_t *) dcp, leafno,
2507                                                dcp->budmin, oldval);
2508                                }
2509
2510                                /* release the buffer and return the error.
2511                                 */
2512                                release_metapage(mp);
2513                                return (rc);
2514                        }
2515                } else {
2516                        /* we're at the top level of the map. update
2517                         * the bmap control page to reflect the size
2518                         * of the maximum free buddy system.
2519                         */
2520                        assert(level == bmp->db_maxlevel);
2521                        if (bmp->db_maxfreebud != oldroot) {
2522                                jfs_error(bmp->db_ipbmap->i_sb,
2523                                          "dbAdjCtl: the maximum free buddy is "
2524                                          "not the old root");
2525                        }
2526                        bmp->db_maxfreebud = dcp->stree[ROOT];
2527                }
2528        }
2529
2530        /* write the buffer.
2531         */
2532        write_metapage(mp);
2533
2534        return (0);
2535}
2536
2537
2538/*
2539 * NAME:        dbSplit()
2540 *
2541 * FUNCTION:    update the leaf of a dmtree with a new value, splitting
2542 *              the leaf from the binary buddy system of the dmtree's
2543 *              leaves, as required.
2544 *
2545 * PARAMETERS:
2546 *      tp      - pointer to the tree containing the leaf.
2547 *      leafno  - the number of the leaf to be updated.
2548 *      splitsz - the size the binary buddy system starting at the leaf
2549 *                must be split to, specified as the log2 number of blocks.
2550 *      newval  - the new value for the leaf.
2551 *
2552 * RETURN VALUES: none
2553 *
2554 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2555 */
2556static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
2557{
2558        int budsz;
2559        int cursz;
2560        s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2561
2562        /* check if the leaf needs to be split.
2563         */
2564        if (leaf[leafno] > tp->dmt_budmin) {
2565                /* the split occurs by cutting the buddy system in half
2566                 * at the specified leaf until we reach the specified
2567                 * size.  pick up the starting split size (current size
2568                 * - 1 in l2) and the corresponding buddy size.
2569                 */
2570                cursz = leaf[leafno] - 1;
2571                budsz = BUDSIZE(cursz, tp->dmt_budmin);
2572
2573                /* split until we reach the specified size.
2574                 */
2575                while (cursz >= splitsz) {
2576                        /* update the buddy's leaf with its new value.
2577                         */
2578                        dbAdjTree(tp, leafno ^ budsz, cursz);
2579
2580                        /* on to the next size and buddy.
2581                         */
2582                        cursz -= 1;
2583                        budsz >>= 1;
2584                }
2585        }
2586
2587        /* adjust the dmap tree to reflect the specified leaf's new
2588         * value.
2589         */
2590        dbAdjTree(tp, leafno, newval);
2591}
2592
2593
2594/*
2595 * NAME:        dbBackSplit()
2596 *
2597 * FUNCTION:    back split the binary buddy system of dmtree leaves
2598 *              that hold a specified leaf until the specified leaf
2599 *              starts its own binary buddy system.
2600 *
2601 *              the allocators typically perform allocations at the start
2602 *              of binary buddy systems and dbSplit() is used to accomplish
2603 *              any required splits.  in some cases, however, allocation
2604 *              may occur in the middle of a binary system and requires a
2605 *              back split, with the split proceeding out from the middle of
2606 *              the system (less efficient) rather than the start of the
2607 *              system (more efficient).  the cases in which a back split
2608 *              is required are rare and are limited to the first allocation
2609 *              within an allocation group which is a part (not first part)
2610 *              of a larger binary buddy system and a few exception cases
2611 *              in which a previous join operation must be backed out.
2612 *
2613 * PARAMETERS:
2614 *      tp      - pointer to the tree containing the leaf.
2615 *      leafno  - the number of the leaf to be updated.
2616 *
2617 * RETURN VALUES: none
2618 *
2619 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2620 */
2621static int dbBackSplit(dmtree_t * tp, int leafno)
2622{
2623        int budsz, bud, w, bsz, size;
2624        int cursz;
2625        s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2626
2627        /* leaf should be part (not first part) of a binary
2628         * buddy system.
2629         */
2630        assert(leaf[leafno] == NOFREE);
2631
2632        /* the back split is accomplished by iteratively finding the leaf
2633         * that starts the buddy system that contains the specified leaf and
2634         * splitting that system in two.  this iteration continues until
2635         * the specified leaf becomes the start of a buddy system.
2636         *
2637         * determine maximum possible l2 size for the specified leaf.
2638         */
2639        size =
2640            LITOL2BSZ(leafno, le32_to_cpu(tp->dmt_l2nleafs),
2641                      tp->dmt_budmin);
2642
2643        /* determine the number of leaves covered by this size.  this
2644         * is the buddy size that we will start with as we search for
2645         * the buddy system that contains the specified leaf.
2646         */
2647        budsz = BUDSIZE(size, tp->dmt_budmin);
2648
2649        /* back split.
2650         */
2651        while (leaf[leafno] == NOFREE) {
2652                /* find the leftmost buddy leaf.
2653                 */
2654                for (w = leafno, bsz = budsz;; bsz <<= 1,
2655                     w = (w < bud) ? w : bud) {
2656                        if (bsz >= le32_to_cpu(tp->dmt_nleafs)) {
2657                                jfs_err("JFS: block map error in dbBackSplit");
2658                                return -EIO;
2659                        }
2660
2661                        /* determine the buddy.
2662                         */
2663                        bud = w ^ bsz;
2664
2665                        /* check if this buddy is the start of the system.
2666                         */
2667                        if (leaf[bud] != NOFREE) {
2668                                /* split the leaf at the start of the
2669                                 * system in two.
2670                                 */
2671                                cursz = leaf[bud] - 1;
2672                                dbSplit(tp, bud, cursz, cursz);
2673                                break;
2674                        }
2675                }
2676        }
2677
2678        if (leaf[leafno] != size) {
2679                jfs_err("JFS: wrong leaf value in dbBackSplit");
2680                return -EIO;
2681        }
2682        return 0;
2683}
2684
2685
2686/*
2687 * NAME:        dbJoin()
2688 *
2689 * FUNCTION:    update the leaf of a dmtree with a new value, joining
2690 *              the leaf with other leaves of the dmtree into a multi-leaf
2691 *              binary buddy system, as required.
2692 *
2693 * PARAMETERS:
2694 *      tp      - pointer to the tree containing the leaf.
2695 *      leafno  - the number of the leaf to be updated.
2696 *      newval  - the new value for the leaf.
2697 *
2698 * RETURN VALUES: none
2699 */
2700static int dbJoin(dmtree_t * tp, int leafno, int newval)
2701{
2702        int budsz, buddy;
2703        s8 *leaf;
2704
2705        /* can the new leaf value require a join with other leaves ?
2706         */
2707        if (newval >= tp->dmt_budmin) {
2708                /* pickup a pointer to the leaves of the tree.
2709                 */
2710                leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2711
2712                /* try to join the specified leaf into a large binary
2713                 * buddy system.  the join proceeds by attempting to join
2714                 * the specified leafno with its buddy (leaf) at new value.
2715                 * if the join occurs, we attempt to join the left leaf
2716                 * of the joined buddies with its buddy at new value + 1.
2717                 * we continue to join until we find a buddy that cannot be
2718                 * joined (does not have a value equal to the size of the
2719                 * last join) or until all leaves have been joined into a
2720                 * single system.
2721                 *
2722                 * get the buddy size (number of words covered) of
2723                 * the new value.
2724                 */
2725                budsz = BUDSIZE(newval, tp->dmt_budmin);
2726
2727                /* try to join.
2728                 */
2729                while (budsz < le32_to_cpu(tp->dmt_nleafs)) {
2730                        /* get the buddy leaf.
2731                         */
2732                        buddy = leafno ^ budsz;
2733
2734                        /* if the leaf's new value is greater than its
2735                         * buddy's value, we join no more.
2736                         */
2737                        if (newval > leaf[buddy])
2738                                break;
2739
2740                        /* It shouldn't be less */
2741                        if (newval < leaf[buddy])
2742                                return -EIO;
2743
2744                        /* check which (leafno or buddy) is the left buddy.
2745                         * the left buddy gets to claim the blocks resulting
2746                         * from the join while the right gets to claim none.
2747                         * the left buddy is also eligible to participate in
2748                         * a join at the next higher level while the right
2749                         * is not.
2750                         *
2751                         */
2752                        if (leafno < buddy) {
2753                                /* leafno is the left buddy.
2754                                 */
2755                                dbAdjTree(tp, buddy, NOFREE);
2756                        } else {
2757                                /* buddy is the left buddy and becomes
2758                                 * leafno.
2759                                 */
2760                                dbAdjTree(tp, leafno, NOFREE);
2761                                leafno = buddy;
2762                        }
2763
2764                        /* on to try the next join.
2765                         */
2766                        newval += 1;
2767                        budsz <<= 1;
2768                }
2769        }
2770
2771        /* update the leaf value.
2772         */
2773        dbAdjTree(tp, leafno, newval);
2774
2775        return 0;
2776}
2777
2778
2779/*
2780 * NAME:        dbAdjTree()
2781 *
2782 * FUNCTION:    update a leaf of a dmtree with a new value, adjusting
2783 *              the dmtree, as required, to reflect the new leaf value.
2784 *              the combination of any buddies must already be done before
2785 *              this is called.
2786 *
2787 * PARAMETERS:
2788 *      tp      - pointer to the tree to be adjusted.
2789 *      leafno  - the number of the leaf to be updated.
2790 *      newval  - the new value for the leaf.
2791 *
2792 * RETURN VALUES: none
2793 */
2794static void dbAdjTree(dmtree_t * tp, int leafno, int newval)
2795{
2796        int lp, pp, k;
2797        int max;
2798
2799        /* pick up the index of the leaf for this leafno.
2800         */
2801        lp = leafno + le32_to_cpu(tp->dmt_leafidx);
2802
2803        /* is the current value the same as the old value ?  if so,
2804         * there is nothing to do.
2805         */
2806        if (tp->dmt_stree[lp] == newval)
2807                return;
2808
2809        /* set the new value.
2810         */
2811        tp->dmt_stree[lp] = newval;
2812
2813        /* bubble the new value up the tree as required.
2814         */
2815        for (k = 0; k < le32_to_cpu(tp->dmt_height); k++) {
2816                /* get the index of the first leaf of the 4 leaf
2817                 * group containing the specified leaf (leafno).
2818                 */
2819                lp = ((lp - 1) & ~0x03) + 1;
2820
2821                /* get the index of the parent of this 4 leaf group.
2822                 */
2823                pp = (lp - 1) >> 2;
2824
2825                /* determine the maximum of the 4 leaves.
2826                 */
2827                max = TREEMAX(&tp->dmt_stree[lp]);
2828
2829                /* if the maximum of the 4 is the same as the
2830                 * parent's value, we're done.
2831                 */
2832                if (tp->dmt_stree[pp] == max)
2833                        break;
2834
2835                /* parent gets new value.
2836                 */
2837                tp->dmt_stree[pp] = max;
2838
2839                /* parent becomes leaf for next go-round.
2840                 */
2841                lp = pp;
2842        }
2843}
2844
2845
2846/*
2847 * NAME:        dbFindLeaf()
2848 *
2849 * FUNCTION:    search a dmtree_t for sufficient free blocks, returning
2850 *              the index of a leaf describing the free blocks if
2851 *              sufficient free blocks are found.
2852 *
2853 *              the search starts at the top of the dmtree_t tree and
2854 *              proceeds down the tree to the leftmost leaf with sufficient
2855 *              free space.
2856 *
2857 * PARAMETERS:
2858 *      tp      - pointer to the tree to be searched.
2859 *      l2nb    - log2 number of free blocks to search for.
2860 *      leafidx - return pointer to be set to the index of the leaf
2861 *                describing at least l2nb free blocks if sufficient
2862 *                free blocks are found.
2863 *
2864 * RETURN VALUES:
2865 *      0       - success
2866 *      -ENOSPC - insufficient free blocks.
2867 */
2868static int dbFindLeaf(dmtree_t * tp, int l2nb, int *leafidx)
2869{
2870        int ti, n = 0, k, x = 0;
2871
2872        /* first check the root of the tree to see if there is
2873         * sufficient free space.
2874         */
2875        if (l2nb > tp->dmt_stree[ROOT])
2876                return -ENOSPC;
2877
2878        /* sufficient free space available. now search down the tree
2879         * starting at the next level for the leftmost leaf that
2880         * describes sufficient free space.
2881         */
2882        for (k = le32_to_cpu(tp->dmt_height), ti = 1;
2883             k > 0; k--, ti = ((ti + n) << 2) + 1) {
2884                /* search the four nodes at this level, starting from
2885                 * the left.
2886                 */
2887                for (x = ti, n = 0; n < 4; n++) {
2888                        /* sufficient free space found.  move to the next
2889                         * level (or quit if this is the last level).
2890                         */
2891                        if (l2nb <= tp->dmt_stree[x + n])
2892                                break;
2893                }
2894
2895                /* better have found something since the higher
2896                 * levels of the tree said it was here.
2897                 */
2898                assert(n < 4);
2899        }
2900
2901        /* set the return to the leftmost leaf describing sufficient
2902         * free space.
2903         */
2904        *leafidx = x + n - le32_to_cpu(tp->dmt_leafidx);
2905
2906        return (0);
2907}
2908
2909
2910/*
2911 * NAME:        dbFindBits()
2912 *
2913 * FUNCTION:    find a specified number of binary buddy free bits within a
2914 *              dmap bitmap word value.
2915 *
2916 *              this routine searches the bitmap value for (1 << l2nb) free
2917 *              bits at (1 << l2nb) alignments within the value.
2918 *
2919 * PARAMETERS:
2920 *      word    -  dmap bitmap word value.
2921 *      l2nb    -  number of free bits specified as a log2 number.
2922 *
2923 * RETURN VALUES:
2924 *      starting bit number of free bits.
2925 */
2926static int dbFindBits(u32 word, int l2nb)
2927{
2928        int bitno, nb;
2929        u32 mask;
2930
2931        /* get the number of bits.
2932         */
2933        nb = 1 << l2nb;
2934        assert(nb <= DBWORD);
2935
2936        /* complement the word so we can use a mask (i.e. 0s represent
2937         * free bits) and compute the mask.
2938         */
2939        word = ~word;
2940        mask = ONES << (DBWORD - nb);
2941
2942        /* scan the word for nb free bits at nb alignments.
2943         */
2944        for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
2945                if ((mask & word) == mask)
2946                        break;
2947        }
2948
2949        ASSERT(bitno < 32);
2950
2951        /* return the bit number.
2952         */
2953        return (bitno);
2954}
2955
2956
2957/*
2958 * NAME:        dbMaxBud(u8 *cp)
2959 *
2960 * FUNCTION:    determine the largest binary buddy string of free
2961 *              bits within 32-bits of the map.
2962 *
2963 * PARAMETERS:
2964 *      cp      -  pointer to the 32-bit value.
2965 *
2966 * RETURN VALUES:
2967 *      largest binary buddy of free bits within a dmap word.
2968 */
2969static int dbMaxBud(u8 * cp)
2970{
2971        signed char tmp1, tmp2;
2972
2973        /* check if the wmap word is all free. if so, the
2974         * free buddy size is BUDMIN.
2975         */
2976        if (*((uint *) cp) == 0)
2977                return (BUDMIN);
2978
2979        /* check if the wmap word is half free. if so, the
2980         * free buddy size is BUDMIN-1.
2981         */
2982        if (*((u16 *) cp) == 0 || *((u16 *) cp + 1) == 0)
2983                return (BUDMIN - 1);
2984
2985        /* not all free or half free. determine the free buddy
2986         * size thru table lookup using quarters of the wmap word.
2987         */
2988        tmp1 = max(budtab[cp[2]], budtab[cp[3]]);
2989        tmp2 = max(budtab[cp[0]], budtab[cp[1]]);
2990        return (max(tmp1, tmp2));
2991}
2992
2993
2994/*
2995 * NAME:        cnttz(uint word)
2996 *
2997 * FUNCTION:    determine the number of trailing zeros within a 32-bit
2998 *              value.
2999 *
3000 * PARAMETERS:
3001 *      value   -  32-bit value to be examined.
3002 *
3003 * RETURN VALUES:
3004 *      count of trailing zeros
3005 */
3006static int cnttz(u32 word)
3007{
3008        int n;
3009
3010        for (n = 0; n < 32; n++, word >>= 1) {
3011                if (word & 0x01)
3012                        break;
3013        }
3014
3015        return (n);
3016}
3017
3018
3019/*
3020 * NAME:        cntlz(u32 value)
3021 *
3022 * FUNCTION:    determine the number of leading zeros within a 32-bit
3023 *              value.
3024 *
3025 * PARAMETERS:
3026 *      value   -  32-bit value to be examined.
3027 *
3028 * RETURN VALUES:
3029 *      count of leading zeros
3030 */
3031static int cntlz(u32 value)
3032{
3033        int n;
3034
3035        for (n = 0; n < 32; n++, value <<= 1) {
3036                if (value & HIGHORDER)
3037                        break;
3038        }
3039        return (n);
3040}
3041
3042
3043/*
3044 * NAME:        blkstol2(s64 nb)
3045 *
3046 * FUNCTION:    convert a block count to its log2 value. if the block
3047 *              count is not a l2 multiple, it is rounded up to the next
3048 *              larger l2 multiple.
3049 *
3050 * PARAMETERS:
3051 *      nb      -  number of blocks
3052 *
3053 * RETURN VALUES:
3054 *      log2 number of blocks
3055 */
3056static int blkstol2(s64 nb)
3057{
3058        int l2nb;
3059        s64 mask;               /* meant to be signed */
3060
3061        mask = (s64) 1 << (64 - 1);
3062
3063        /* count the leading bits.
3064         */
3065        for (l2nb = 0; l2nb < 64; l2nb++, mask >>= 1) {
3066                /* leading bit found.
3067                 */
3068                if (nb & mask) {
3069                        /* determine the l2 value.
3070                         */
3071                        l2nb = (64 - 1) - l2nb;
3072
3073                        /* check if we need to round up.
3074                         */
3075                        if (~mask & nb)
3076                                l2nb++;
3077
3078                        return (l2nb);
3079                }
3080        }
3081        assert(0);
3082        return 0;               /* fix compiler warning */
3083}
3084
3085
3086/*
3087 * NAME:        dbAllocBottomUp()
3088 *
3089 * FUNCTION:    alloc the specified block range from the working block
3090 *              allocation map.
3091 *
3092 *              the blocks will be alloc from the working map one dmap
3093 *              at a time.
3094 *
3095 * PARAMETERS:
3096 *      ip      -  pointer to in-core inode;
3097 *      blkno   -  starting block number to be freed.
3098 *      nblocks -  number of blocks to be freed.
3099 *
3100 * RETURN VALUES:
3101 *      0       - success
3102 *      -EIO    - i/o error
3103 */
3104int dbAllocBottomUp(struct inode *ip, s64 blkno, s64 nblocks)
3105{
3106        struct metapage *mp;
3107        struct dmap *dp;
3108        int nb, rc;
3109        s64 lblkno, rem;
3110        struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
3111        struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
3112
3113        IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
3114
3115        /* block to be allocated better be within the mapsize. */
3116        ASSERT(nblocks <= bmp->db_mapsize - blkno);
3117
3118        /*
3119         * allocate the blocks a dmap at a time.
3120         */
3121        mp = NULL;
3122        for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
3123                /* release previous dmap if any */
3124                if (mp) {
3125                        write_metapage(mp);
3126                }
3127
3128                /* get the buffer for the current dmap. */
3129                lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
3130                mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
3131                if (mp == NULL) {
3132                        IREAD_UNLOCK(ipbmap);
3133                        return -EIO;
3134                }
3135                dp = (struct dmap *) mp->data;
3136
3137                /* determine the number of blocks to be allocated from
3138                 * this dmap.
3139                 */
3140                nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
3141
3142                /* allocate the blocks. */
3143                if ((rc = dbAllocDmapBU(bmp, dp, blkno, nb))) {
3144                        release_metapage(mp);
3145                        IREAD_UNLOCK(ipbmap);
3146                        return (rc);
3147                }
3148        }
3149
3150        /* write the last buffer. */
3151        write_metapage(mp);
3152
3153        IREAD_UNLOCK(ipbmap);
3154
3155        return (0);
3156}
3157
3158
3159static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
3160                         int nblocks)
3161{
3162        int rc;
3163        int dbitno, word, rembits, nb, nwords, wbitno, agno;
3164        s8 oldroot;
3165        struct dmaptree *tp = (struct dmaptree *) & dp->tree;
3166
3167        /* save the current value of the root (i.e. maximum free string)
3168         * of the dmap tree.
3169         */
3170        oldroot = tp->stree[ROOT];
3171
3172        /* determine the bit number and word within the dmap of the
3173         * starting block.
3174         */
3175        dbitno = blkno & (BPERDMAP - 1);
3176        word = dbitno >> L2DBWORD;
3177
3178        /* block range better be within the dmap */
3179        assert(dbitno + nblocks <= BPERDMAP);
3180
3181        /* allocate the bits of the dmap's words corresponding to the block
3182         * range. not all bits of the first and last words may be contained
3183         * within the block range.  if this is the case, we'll work against
3184         * those words (i.e. partial first and/or last) on an individual basis
3185         * (a single pass), allocating the bits of interest by hand and
3186         * updating the leaf corresponding to the dmap word. a single pass
3187         * will be used for all dmap words fully contained within the
3188         * specified range.  within this pass, the bits of all fully contained
3189         * dmap words will be marked as free in a single shot and the leaves
3190         * will be updated. a single leaf may describe the free space of
3191         * multiple dmap words, so we may update only a subset of the actual
3192         * leaves corresponding to the dmap words of the block range.
3193         */
3194        for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
3195                /* determine the bit number within the word and
3196                 * the number of bits within the word.
3197                 */
3198                wbitno = dbitno & (DBWORD - 1);
3199                nb = min(rembits, DBWORD - wbitno);
3200
3201                /* check if only part of a word is to be allocated.
3202                 */
3203                if (nb < DBWORD) {
3204                        /* allocate (set to 1) the appropriate bits within
3205                         * this dmap word.
3206                         */
3207                        dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
3208                                                      >> wbitno);
3209
3210                        word++;
3211                } else {
3212                        /* one or more dmap words are fully contained
3213                         * within the block range.  determine how many
3214                         * words and allocate (set to 1) the bits of these
3215                         * words.
3216                         */
3217                        nwords = rembits >> L2DBWORD;
3218                        memset(&dp->wmap[word], (int) ONES, nwords * 4);
3219
3220                        /* determine how many bits */
3221                        nb = nwords << L2DBWORD;
3222                        word += nwords;
3223                }
3224        }
3225
3226        /* update the free count for this dmap */
3227        le32_add_cpu(&dp->nfree, -nblocks);
3228
3229        /* reconstruct summary tree */
3230        dbInitDmapTree(dp);
3231
3232        BMAP_LOCK(bmp);
3233
3234        /* if this allocation group is completely free,
3235         * update the highest active allocation group number
3236         * if this allocation group is the new max.
3237         */
3238        agno = blkno >> bmp->db_agl2size;
3239        if (agno > bmp->db_maxag)
3240                bmp->db_maxag = agno;
3241
3242        /* update the free count for the allocation group and map */
3243        bmp->db_agfree[agno] -= nblocks;
3244        bmp->db_nfree -= nblocks;
3245
3246        BMAP_UNLOCK(bmp);
3247
3248        /* if the root has not changed, done. */
3249        if (tp->stree[ROOT] == oldroot)
3250                return (0);
3251
3252        /* root changed. bubble the change up to the dmap control pages.
3253         * if the adjustment of the upper level control pages fails,
3254         * backout the bit allocation (thus making everything consistent).
3255         */
3256        if ((rc = dbAdjCtl(bmp, blkno, tp->stree[ROOT], 1, 0)))
3257                dbFreeBits(bmp, dp, blkno, nblocks);
3258
3259        return (rc);
3260}
3261
3262
3263/*
3264 * NAME:        dbExtendFS()
3265 *
3266 * FUNCTION:    extend bmap from blkno for nblocks;
3267 *              dbExtendFS() updates bmap ready for dbAllocBottomUp();
3268 *
3269 * L2
3270 *  |
3271 *   L1---------------------------------L1
3272 *    |                                  |
3273 *     L0---------L0---------L0           L0---------L0---------L0
3274 *      |          |          |            |          |          |
3275 *       d0,...,dn  d0,...,dn  d0,...,dn    d0,...,dn  d0,...,dn  d0,.,dm;
3276 * L2L1L0d0,...,dnL0d0,...,dnL0d0,...,dnL1L0d0,...,dnL0d0,...,dnL0d0,..dm
3277 *
3278 * <---old---><----------------------------extend----------------------->
3279 */
3280int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks)
3281{
3282        struct jfs_sb_info *sbi = JFS_SBI(ipbmap->i_sb);
3283        int nbperpage = sbi->nbperpage;
3284        int i, i0 = true, j, j0 = true, k, n;
3285        s64 newsize;
3286        s64 p;
3287        struct metapage *mp, *l2mp, *l1mp = NULL, *l0mp = NULL;
3288        struct dmapctl *l2dcp, *l1dcp, *l0dcp;
3289        struct dmap *dp;
3290        s8 *l0leaf, *l1leaf, *l2leaf;
3291        struct bmap *bmp = sbi->bmap;
3292        int agno, l2agsize, oldl2agsize;
3293        s64 ag_rem;
3294
3295        newsize = blkno + nblocks;
3296
3297        jfs_info("dbExtendFS: blkno:%Ld nblocks:%Ld newsize:%Ld",
3298                 (long long) blkno, (long long) nblocks, (long long) newsize);
3299
3300        /*
3301         *      initialize bmap control page.
3302         *
3303         * all the data in bmap control page should exclude
3304         * the mkfs hidden dmap page.
3305         */
3306
3307        /* update mapsize */
3308        bmp->db_mapsize = newsize;
3309        bmp->db_maxlevel = BMAPSZTOLEV(bmp->db_mapsize);
3310
3311        /* compute new AG size */
3312        l2agsize = dbGetL2AGSize(newsize);
3313        oldl2agsize = bmp->db_agl2size;
3314
3315        bmp->db_agl2size = l2agsize;
3316        bmp->db_agsize = 1 << l2agsize;
3317
3318        /* compute new number of AG */
3319        agno = bmp->db_numag;
3320        bmp->db_numag = newsize >> l2agsize;
3321        bmp->db_numag += ((u32) newsize % (u32) bmp->db_agsize) ? 1 : 0;
3322
3323        /*
3324         *      reconfigure db_agfree[]
3325         * from old AG configuration to new AG configuration;
3326         *
3327         * coalesce contiguous k (newAGSize/oldAGSize) AGs;
3328         * i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
3329         * note: new AG size = old AG size * (2**x).
3330         */
3331        if (l2agsize == oldl2agsize)
3332                goto extend;
3333        k = 1 << (l2agsize - oldl2agsize);
3334        ag_rem = bmp->db_agfree[0];     /* save agfree[0] */
3335        for (i = 0, n = 0; i < agno; n++) {
3336                bmp->db_agfree[n] = 0;  /* init collection point */
3337
3338                /* coalesce contiguous k AGs; */
3339                for (j = 0; j < k && i < agno; j++, i++) {
3340                        /* merge AGi to AGn */
3341                        bmp->db_agfree[n] += bmp->db_agfree[i];
3342                }
3343        }
3344        bmp->db_agfree[0] += ag_rem;    /* restore agfree[0] */
3345
3346        for (; n < MAXAG; n++)
3347                bmp->db_agfree[n] = 0;
3348
3349        /*
3350         * update highest active ag number
3351         */
3352
3353        bmp->db_maxag = bmp->db_maxag / k;
3354
3355        /*
3356         *      extend bmap
3357         *
3358         * update bit maps and corresponding level control pages;
3359         * global control page db_nfree, db_agfree[agno], db_maxfreebud;
3360         */
3361      extend:
3362        /* get L2 page */
3363        p = BMAPBLKNO + nbperpage;      /* L2 page */
3364        l2mp = read_metapage(ipbmap, p, PSIZE, 0);
3365        if (!l2mp) {
3366                jfs_error(ipbmap->i_sb, "dbExtendFS: L2 page could not be read");
3367                return -EIO;
3368        }
3369        l2dcp = (struct dmapctl *) l2mp->data;
3370
3371        /* compute start L1 */
3372        k = blkno >> L2MAXL1SIZE;
3373        l2leaf = l2dcp->stree + CTLLEAFIND + k;
3374        p = BLKTOL1(blkno, sbi->l2nbperpage);   /* L1 page */
3375
3376        /*
3377         * extend each L1 in L2
3378         */
3379        for (; k < LPERCTL; k++, p += nbperpage) {
3380                /* get L1 page */
3381                if (j0) {
3382                        /* read in L1 page: (blkno & (MAXL1SIZE - 1)) */
3383                        l1mp = read_metapage(ipbmap, p, PSIZE, 0);
3384                        if (l1mp == NULL)
3385                                goto errout;
3386                        l1dcp = (struct dmapctl *) l1mp->data;
3387
3388                        /* compute start L0 */
3389                        j = (blkno & (MAXL1SIZE - 1)) >> L2MAXL0SIZE;
3390                        l1leaf = l1dcp->stree + CTLLEAFIND + j;
3391                        p = BLKTOL0(blkno, sbi->l2nbperpage);
3392                        j0 = false;
3393                } else {
3394                        /* assign/init L1 page */
3395                        l1mp = get_metapage(ipbmap, p, PSIZE, 0);
3396                        if (l1mp == NULL)
3397                                goto errout;
3398
3399                        l1dcp = (struct dmapctl *) l1mp->data;
3400
3401                        /* compute start L0 */
3402                        j = 0;
3403                        l1leaf = l1dcp->stree + CTLLEAFIND;
3404                        p += nbperpage; /* 1st L0 of L1.k */
3405                }
3406
3407                /*
3408                 * extend each L0 in L1
3409                 */
3410                for (; j < LPERCTL; j++) {
3411                        /* get L0 page */
3412                        if (i0) {
3413                                /* read in L0 page: (blkno & (MAXL0SIZE - 1)) */
3414
3415                                l0mp = read_metapage(ipbmap, p, PSIZE, 0);
3416                                if (l0mp == NULL)
3417                                        goto errout;
3418                                l0dcp = (struct dmapctl *) l0mp->data;
3419
3420                                /* compute start dmap */
3421                                i = (blkno & (MAXL0SIZE - 1)) >>
3422                                    L2BPERDMAP;
3423                                l0leaf = l0dcp->stree + CTLLEAFIND + i;
3424                                p = BLKTODMAP(blkno,
3425                                              sbi->l2nbperpage);
3426                                i0 = false;
3427                        } else {
3428                                /* assign/init L0 page */
3429                                l0mp = get_metapage(ipbmap, p, PSIZE, 0);
3430                                if (l0mp == NULL)
3431                                        goto errout;
3432
3433                                l0dcp = (struct dmapctl *) l0mp->data;
3434
3435                                /* compute start dmap */
3436                                i = 0;
3437                                l0leaf = l0dcp->stree + CTLLEAFIND;
3438                                p += nbperpage; /* 1st dmap of L0.j */
3439                        }
3440
3441                        /*
3442                         * extend each dmap in L0
3443                         */
3444                        for (; i < LPERCTL; i++) {
3445                                /*
3446                                 * reconstruct the dmap page, and
3447                                 * initialize corresponding parent L0 leaf
3448                                 */
3449                                if ((n = blkno & (BPERDMAP - 1))) {
3450                                        /* read in dmap page: */
3451                                        mp = read_metapage(ipbmap, p,
3452                                                           PSIZE, 0);
3453                                        if (mp == NULL)
3454                                                goto errout;
3455                                        n = min(nblocks, (s64)BPERDMAP - n);
3456                                } else {
3457                                        /* assign/init dmap page */
3458                                        mp = read_metapage(ipbmap, p,
3459                                                           PSIZE, 0);
3460                                        if (mp == NULL)
3461                                                goto errout;
3462
3463                                        n = min(nblocks, (s64)BPERDMAP);
3464                                }
3465
3466                                dp = (struct dmap *) mp->data;
3467                                *l0leaf = dbInitDmap(dp, blkno, n);
3468
3469                                bmp->db_nfree += n;
3470                                agno = le64_to_cpu(dp->start) >> l2agsize;
3471                                bmp->db_agfree[agno] += n;
3472
3473                                write_metapage(mp);
3474
3475                                l0leaf++;
3476                                p += nbperpage;
3477
3478                                blkno += n;
3479                                nblocks -= n;
3480                                if (nblocks == 0)
3481                                        break;
3482                        }       /* for each dmap in a L0 */
3483
3484                        /*
3485                         * build current L0 page from its leaves, and
3486                         * initialize corresponding parent L1 leaf
3487                         */
3488                        *l1leaf = dbInitDmapCtl(l0dcp, 0, ++i);
3489                        write_metapage(l0mp);
3490                        l0mp = NULL;
3491
3492                        if (nblocks)
3493                                l1leaf++;       /* continue for next L0 */
3494                        else {
3495                                /* more than 1 L0 ? */
3496                                if (j > 0)
3497                                        break;  /* build L1 page */
3498                                else {
3499                                        /* summarize in global bmap page */
3500                                        bmp->db_maxfreebud = *l1leaf;
3501                                        release_metapage(l1mp);
3502                                        release_metapage(l2mp);
3503                                        goto finalize;
3504                                }
3505                        }
3506                }               /* for each L0 in a L1 */
3507
3508                /*
3509                 * build current L1 page from its leaves, and
3510                 * initialize corresponding parent L2 leaf
3511                 */
3512                *l2leaf = dbInitDmapCtl(l1dcp, 1, ++j);
3513                write_metapage(l1mp);
3514                l1mp = NULL;
3515
3516                if (nblocks)
3517                        l2leaf++;       /* continue for next L1 */
3518                else {
3519                        /* more than 1 L1 ? */
3520                        if (k > 0)
3521                                break;  /* build L2 page */
3522                        else {
3523                                /* summarize in global bmap page */
3524                                bmp->db_maxfreebud = *l2leaf;
3525                                release_metapage(l2mp);
3526                                goto finalize;
3527                        }
3528                }
3529        }                       /* for each L1 in a L2 */
3530
3531        jfs_error(ipbmap->i_sb,
3532                  "dbExtendFS: function has not returned as expected");
3533errout:
3534        if (l0mp)
3535                release_metapage(l0mp);
3536        if (l1mp)
3537                release_metapage(l1mp);
3538        release_metapage(l2mp);
3539        return -EIO;
3540
3541        /*
3542         *      finalize bmap control page
3543         */
3544finalize:
3545
3546        return 0;
3547}
3548
3549
3550/*
3551 *      dbFinalizeBmap()
3552 */
3553void dbFinalizeBmap(struct inode *ipbmap)
3554{
3555        struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
3556        int actags, inactags, l2nl;
3557        s64 ag_rem, actfree, inactfree, avgfree;
3558        int i, n;
3559
3560        /*
3561         *      finalize bmap control page
3562         */
3563//finalize:
3564        /*
3565         * compute db_agpref: preferred ag to allocate from
3566         * (the leftmost ag with average free space in it);
3567         */
3568//agpref:
3569        /* get the number of active ags and inacitve ags */
3570        actags = bmp->db_maxag + 1;
3571        inactags = bmp->db_numag - actags;
3572        ag_rem = bmp->db_mapsize & (bmp->db_agsize - 1);        /* ??? */
3573
3574        /* determine how many blocks are in the inactive allocation
3575         * groups. in doing this, we must account for the fact that
3576         * the rightmost group might be a partial group (i.e. file
3577         * system size is not a multiple of the group size).
3578         */
3579        inactfree = (inactags && ag_rem) ?
3580            ((inactags - 1) << bmp->db_agl2size) + ag_rem
3581            : inactags << bmp->db_agl2size;
3582
3583        /* determine how many free blocks are in the active
3584         * allocation groups plus the average number of free blocks
3585         * within the active ags.
3586         */
3587        actfree = bmp->db_nfree - inactfree;
3588        avgfree = (u32) actfree / (u32) actags;
3589
3590        /* if the preferred allocation group has not average free space.
3591         * re-establish the preferred group as the leftmost
3592         * group with average free space.
3593         */
3594        if (bmp->db_agfree[bmp->db_agpref] < avgfree) {
3595                for (bmp->db_agpref = 0; bmp->db_agpref < actags;
3596                     bmp->db_agpref++) {
3597                        if (bmp->db_agfree[bmp->db_agpref] >= avgfree)
3598                                break;
3599                }
3600                if (bmp->db_agpref >= bmp->db_numag) {
3601                        jfs_error(ipbmap->i_sb,
3602                                  "cannot find ag with average freespace");
3603                }
3604        }
3605
3606        /*
3607         * compute db_aglevel, db_agheight, db_width, db_agstart:
3608         * an ag is covered in aglevel dmapctl summary tree,
3609         * at agheight level height (from leaf) with agwidth number of nodes
3610         * each, which starts at agstart index node of the smmary tree node
3611         * array;
3612         */
3613        bmp->db_aglevel = BMAPSZTOLEV(bmp->db_agsize);
3614        l2nl =
3615            bmp->db_agl2size - (L2BPERDMAP + bmp->db_aglevel * L2LPERCTL);
3616        bmp->db_agheight = l2nl >> 1;
3617        bmp->db_agwidth = 1 << (l2nl - (bmp->db_agheight << 1));
3618        for (i = 5 - bmp->db_agheight, bmp->db_agstart = 0, n = 1; i > 0;
3619             i--) {
3620                bmp->db_agstart += n;
3621                n <<= 2;
3622        }
3623
3624}
3625
3626
3627/*
3628 * NAME:        dbInitDmap()/ujfs_idmap_page()
3629 *
3630 * FUNCTION:    initialize working/persistent bitmap of the dmap page
3631 *              for the specified number of blocks:
3632 *
3633 *              at entry, the bitmaps had been initialized as free (ZEROS);
3634 *              The number of blocks will only account for the actually
3635 *              existing blocks. Blocks which don't actually exist in
3636 *              the aggregate will be marked as allocated (ONES);
3637 *
3638 * PARAMETERS:
3639 *      dp      - pointer to page of map
3640 *      nblocks - number of blocks this page
3641 *
3642 * RETURNS: NONE
3643 */
3644static int dbInitDmap(struct dmap * dp, s64 Blkno, int nblocks)
3645{
3646        int blkno, w, b, r, nw, nb, i;
3647
3648        /* starting block number within the dmap */
3649        blkno = Blkno & (BPERDMAP - 1);
3650
3651        if (blkno == 0) {
3652                dp->nblocks = dp->nfree = cpu_to_le32(nblocks);
3653                dp->start = cpu_to_le64(Blkno);
3654
3655                if (nblocks == BPERDMAP) {
3656                        memset(&dp->wmap[0], 0, LPERDMAP * 4);
3657                        memset(&dp->pmap[0], 0, LPERDMAP * 4);
3658                        goto initTree;
3659                }
3660        } else {
3661                le32_add_cpu(&dp->nblocks, nblocks);
3662                le32_add_cpu(&dp->nfree, nblocks);
3663        }
3664
3665        /* word number containing start block number */
3666        w = blkno >> L2DBWORD;
3667
3668        /*
3669         * free the bits corresponding to the block range (ZEROS):
3670         * note: not all bits of the first and last words may be contained
3671         * within the block range.
3672         */
3673        for (r = nblocks; r > 0; r -= nb, blkno += nb) {
3674                /* number of bits preceding range to be freed in the word */
3675                b = blkno & (DBWORD - 1);
3676                /* number of bits to free in the word */
3677                nb = min(r, DBWORD - b);
3678
3679                /* is partial word to be freed ? */
3680                if (nb < DBWORD) {
3681                        /* free (set to 0) from the bitmap word */
3682                        dp->wmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3683                                                     >> b));
3684                        dp->pmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3685                                                     >> b));
3686
3687                        /* skip the word freed */
3688                        w++;
3689                } else {
3690                        /* free (set to 0) contiguous bitmap words */
3691                        nw = r >> L2DBWORD;
3692                        memset(&dp->wmap[w], 0, nw * 4);
3693                        memset(&dp->pmap[w], 0, nw * 4);
3694
3695                        /* skip the words freed */
3696                        nb = nw << L2DBWORD;
3697                        w += nw;
3698                }
3699        }
3700
3701        /*
3702         * mark bits following the range to be freed (non-existing
3703         * blocks) as allocated (ONES)
3704         */
3705
3706        if (blkno == BPERDMAP)
3707                goto initTree;
3708
3709        /* the first word beyond the end of existing blocks */
3710        w = blkno >> L2DBWORD;
3711
3712        /* does nblocks fall on a 32-bit boundary ? */
3713        b = blkno & (DBWORD - 1);
3714        if (b) {
3715                /* mark a partial word allocated */
3716                dp->wmap[w] = dp->pmap[w] = cpu_to_le32(ONES >> b);
3717                w++;
3718        }
3719
3720        /* set the rest of the words in the page to allocated (ONES) */
3721        for (i = w; i < LPERDMAP; i++)
3722                dp->pmap[i] = dp->wmap[i] = cpu_to_le32(ONES);
3723
3724        /*
3725         * init tree
3726         */
3727      initTree:
3728        return (dbInitDmapTree(dp));
3729}
3730
3731
3732/*
3733 * NAME:        dbInitDmapTree()/ujfs_complete_dmap()
3734 *
3735 * FUNCTION:    initialize summary tree of the specified dmap:
3736 *
3737 *              at entry, bitmap of the dmap has been initialized;
3738 *
3739 * PARAMETERS:
3740 *      dp      - dmap to complete
3741 *      blkno   - starting block number for this dmap
3742 *      treemax - will be filled in with max free for this dmap
3743 *
3744 * RETURNS:     max free string at the root of the tree
3745 */
3746static int dbInitDmapTree(struct dmap * dp)
3747{
3748        struct dmaptree *tp;
3749        s8 *cp;
3750        int i;
3751
3752        /* init fixed info of tree */
3753        tp = &dp->tree;
3754        tp->nleafs = cpu_to_le32(LPERDMAP);
3755        tp->l2nleafs = cpu_to_le32(L2LPERDMAP);
3756        tp->leafidx = cpu_to_le32(LEAFIND);
3757        tp->height = cpu_to_le32(4);
3758        tp->budmin = BUDMIN;
3759
3760        /* init each leaf from corresponding wmap word:
3761         * note: leaf is set to NOFREE(-1) if all blocks of corresponding
3762         * bitmap word are allocated.
3763         */
3764        cp = tp->stree + le32_to_cpu(tp->leafidx);
3765        for (i = 0; i < LPERDMAP; i++)
3766                *cp++ = dbMaxBud((u8 *) & dp->wmap[i]);
3767
3768        /* build the dmap's binary buddy summary tree */
3769        return (dbInitTree(tp));
3770}
3771
3772
3773/*
3774 * NAME:        dbInitTree()/ujfs_adjtree()
3775 *
3776 * FUNCTION:    initialize binary buddy summary tree of a dmap or dmapctl.
3777 *
3778 *              at entry, the leaves of the tree has been initialized
3779 *              from corresponding bitmap word or root of summary tree
3780 *              of the child control page;
3781 *              configure binary buddy system at the leaf level, then
3782 *              bubble up the values of the leaf nodes up the tree.
3783 *
3784 * PARAMETERS:
3785 *      cp      - Pointer to the root of the tree
3786 *      l2leaves- Number of leaf nodes as a power of 2
3787 *      l2min   - Number of blocks that can be covered by a leaf
3788 *                as a power of 2
3789 *
3790 * RETURNS: max free string at the root of the tree
3791 */
3792static int dbInitTree(struct dmaptree * dtp)
3793{
3794        int l2max, l2free, bsize, nextb, i;
3795        int child, parent, nparent;
3796        s8 *tp, *cp, *cp1;
3797
3798        tp = dtp->stree;
3799
3800        /* Determine the maximum free string possible for the leaves */
3801        l2max = le32_to_cpu(dtp->l2nleafs) + dtp->budmin;
3802
3803        /*
3804         * configure the leaf levevl into binary buddy system
3805         *
3806         * Try to combine buddies starting with a buddy size of 1
3807         * (i.e. two leaves). At a buddy size of 1 two buddy leaves
3808         * can be combined if both buddies have a maximum free of l2min;
3809         * the combination will result in the left-most buddy leaf having
3810         * a maximum free of l2min+1.
3811         * After processing all buddies for a given size, process buddies
3812         * at the next higher buddy size (i.e. current size * 2) and
3813         * the next maximum free (current free + 1).
3814         * This continues until the maximum possible buddy combination
3815         * yields maximum free.
3816         */
3817        for (l2free = dtp->budmin, bsize = 1; l2free < l2max;
3818             l2free++, bsize = nextb) {
3819                /* get next buddy size == current buddy pair size */
3820                nextb = bsize << 1;
3821
3822                /* scan each adjacent buddy pair at current buddy size */
3823                for (i = 0, cp = tp + le32_to_cpu(dtp->leafidx);
3824                     i < le32_to_cpu(dtp->nleafs);
3825                     i += nextb, cp += nextb) {
3826                        /* coalesce if both adjacent buddies are max free */
3827                        if (*cp == l2free && *(cp + bsize) == l2free) {
3828                                *cp = l2free + 1;       /* left take right */
3829                                *(cp + bsize) = -1;     /* right give left */
3830                        }
3831                }
3832        }
3833
3834        /*
3835         * bubble summary information of leaves up the tree.
3836         *
3837         * Starting at the leaf node level, the four nodes described by
3838         * the higher level parent node are compared for a maximum free and
3839         * this maximum becomes the value of the parent node.
3840         * when all lower level nodes are processed in this fashion then
3841         * move up to the next level (parent becomes a lower level node) and
3842         * continue the process for that level.
3843         */
3844        for (child = le32_to_cpu(dtp->leafidx),
3845             nparent = le32_to_cpu(dtp->nleafs) >> 2;
3846             nparent > 0; nparent >>= 2, child = parent) {
3847                /* get index of 1st node of parent level */
3848                parent = (child - 1) >> 2;
3849
3850                /* set the value of the parent node as the maximum
3851                 * of the four nodes of the current level.
3852                 */
3853                for (i = 0, cp = tp + child, cp1 = tp + parent;
3854                     i < nparent; i++, cp += 4, cp1++)
3855                        *cp1 = TREEMAX(cp);
3856        }
3857
3858        return (*tp);
3859}
3860
3861
3862/*
3863 *      dbInitDmapCtl()
3864 *
3865 * function: initialize dmapctl page
3866 */
3867static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i)
3868{                               /* start leaf index not covered by range */
3869        s8 *cp;
3870
3871        dcp->nleafs = cpu_to_le32(LPERCTL);
3872        dcp->l2nleafs = cpu_to_le32(L2LPERCTL);
3873        dcp->leafidx = cpu_to_le32(CTLLEAFIND);
3874        dcp->height = cpu_to_le32(5);
3875        dcp->budmin = L2BPERDMAP + L2LPERCTL * level;
3876
3877        /*
3878         * initialize the leaves of current level that were not covered
3879         * by the specified input block range (i.e. the leaves have no
3880         * low level dmapctl or dmap).
3881         */
3882        cp = &dcp->stree[CTLLEAFIND + i];
3883        for (; i < LPERCTL; i++)
3884                *cp++ = NOFREE;
3885
3886        /* build the dmap's binary buddy summary tree */
3887        return (dbInitTree((struct dmaptree *) dcp));
3888}
3889
3890
3891/*
3892 * NAME:        dbGetL2AGSize()/ujfs_getagl2size()
3893 *
3894 * FUNCTION:    Determine log2(allocation group size) from aggregate size
3895 *
3896 * PARAMETERS:
3897 *      nblocks - Number of blocks in aggregate
3898 *
3899 * RETURNS: log2(allocation group size) in aggregate blocks
3900 */
3901static int dbGetL2AGSize(s64 nblocks)
3902{
3903        s64 sz;
3904        s64 m;
3905        int l2sz;
3906
3907        if (nblocks < BPERDMAP * MAXAG)
3908                return (L2BPERDMAP);
3909
3910        /* round up aggregate size to power of 2 */
3911        m = ((u64) 1 << (64 - 1));
3912        for (l2sz = 64; l2sz >= 0; l2sz--, m >>= 1) {
3913                if (m & nblocks)
3914                        break;
3915        }
3916
3917        sz = (s64) 1 << l2sz;
3918        if (sz < nblocks)
3919                l2sz += 1;
3920
3921        /* agsize = roundupSize/max_number_of_ag */
3922        return (l2sz - L2MAXAG);
3923}
3924
3925
3926/*
3927 * NAME:        dbMapFileSizeToMapSize()
3928 *
3929 * FUNCTION:    compute number of blocks the block allocation map file
3930 *              can cover from the map file size;
3931 *
3932 * RETURNS:     Number of blocks which can be covered by this block map file;
3933 */
3934
3935/*
3936 * maximum number of map pages at each level including control pages
3937 */
3938#define MAXL0PAGES      (1 + LPERCTL)
3939#define MAXL1PAGES      (1 + LPERCTL * MAXL0PAGES)
3940#define MAXL2PAGES      (1 + LPERCTL * MAXL1PAGES)
3941
3942/*
3943 * convert number of map pages to the zero origin top dmapctl level
3944 */
3945#define BMAPPGTOLEV(npages)     \
3946        (((npages) <= 3 + MAXL0PAGES) ? 0 : \
3947         ((npages) <= 2 + MAXL1PAGES) ? 1 : 2)
3948
3949s64 dbMapFileSizeToMapSize(struct inode * ipbmap)
3950{
3951        struct super_block *sb = ipbmap->i_sb;
3952        s64 nblocks;
3953        s64 npages, ndmaps;
3954        int level, i;
3955        int complete, factor;
3956
3957        nblocks = ipbmap->i_size >> JFS_SBI(sb)->l2bsize;
3958        npages = nblocks >> JFS_SBI(sb)->l2nbperpage;
3959        level = BMAPPGTOLEV(npages);
3960
3961        /* At each level, accumulate the number of dmap pages covered by
3962         * the number of full child levels below it;
3963         * repeat for the last incomplete child level.
3964         */
3965        ndmaps = 0;
3966        npages--;               /* skip the first global control page */
3967        /* skip higher level control pages above top level covered by map */
3968        npages -= (2 - level);
3969        npages--;               /* skip top level's control page */
3970        for (i = level; i >= 0; i--) {
3971                factor =
3972                    (i == 2) ? MAXL1PAGES : ((i == 1) ? MAXL0PAGES : 1);
3973                complete = (u32) npages / factor;
3974                ndmaps += complete * ((i == 2) ? LPERCTL * LPERCTL :
3975                                      ((i == 1) ? LPERCTL : 1));
3976
3977                /* pages in last/incomplete child */
3978                npages = (u32) npages % factor;
3979                /* skip incomplete child's level control page */
3980                npages--;
3981        }
3982
3983        /* convert the number of dmaps into the number of blocks
3984         * which can be covered by the dmaps;
3985         */
3986        nblocks = ndmaps << L2BPERDMAP;
3987
3988        return (nblocks);
3989}
3990
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