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TOMOYO Linux Cross Reference
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  */
 75 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 76                         int nblocks);
 77 static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval);
 78 static int dbBackSplit(dmtree_t * tp, int leafno);
 79 static int dbJoin(dmtree_t * tp, int leafno, int newval);
 80 static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
 81 static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
 82                     int level);
 83 static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results);
 84 static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
 85                        int nblocks);
 86 static int dbAllocNear(struct bmap * bmp, struct dmap * dp, s64 blkno,
 87                        int nblocks,
 88                        int l2nb, s64 * results);
 89 static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
 90                        int nblocks);
 91 static int dbAllocDmapLev(struct bmap * bmp, struct dmap * dp, int nblocks,
 92                           int l2nb,
 93                           s64 * results);
 94 static int dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb,
 95                      s64 * results);
 96 static int dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno,
 97                       s64 * results);
 98 static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks);
 99 static int dbFindBits(u32 word, int l2nb);
100 static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno);
101 static int dbFindLeaf(dmtree_t * tp, int l2nb, int *leafidx);
102 static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
103                       int nblocks);
104 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
105                       int nblocks);
106 static int dbMaxBud(u8 * cp);
107 s64 dbMapFileSizeToMapSize(struct inode *ipbmap);
108 static int blkstol2(s64 nb);
109 
110 static int cntlz(u32 value);
111 static int cnttz(u32 word);
112 
113 static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
114                          int nblocks);
115 static int dbInitDmap(struct dmap * dp, s64 blkno, int nblocks);
116 static int dbInitDmapTree(struct dmap * dp);
117 static int dbInitTree(struct dmaptree * dtp);
118 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i);
119 static 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  */
129 static 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  */
165 int 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  */
242 int 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  */
263 int 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  */
332 int 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  */
417 int
418 dbUpdatePMap(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  */
598 int 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 */
649 unlock:
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  */
695 int 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  */
888 int 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  */
972 int
973 dbReAlloc(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  */
1021 static 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  */
1122 static 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  */
1254 static int
1255 dbAllocNear(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  */
1364 static int
1365 dbAllocAG(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  */
1566 static 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  */
1620 static 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  */
1738 static int
1739 dbAllocCtl(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  */
1890 static int
1891 dbAllocDmapLev(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  */
1954 static 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  */
2009 static 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  */
2071 static 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  */
2218 static 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  */
2401 static int
2402 dbAdjCtl(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  */
2556 static 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  */
2621 static 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  */
2700 static 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  */
2794 static 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  */
2868 static 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  */
2926 static 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  */
2969 static 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  */
3006 static 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  */
3031 static 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  */
3056 static 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  */
3104 int 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 
3159 static 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, *leaf;
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         /* pick up a pointer to the leaves of the dmap tree */
3173         leaf = tp->stree + LEAFIND;
3174 
3175         /* determine the bit number and word within the dmap of the
3176          * starting block.
3177          */
3178         dbitno = blkno & (BPERDMAP - 1);
3179         word = dbitno >> L2DBWORD;
3180 
3181         /* block range better be within the dmap */
3182         assert(dbitno + nblocks <= BPERDMAP);
3183 
3184         /* allocate the bits of the dmap's words corresponding to the block
3185          * range. not all bits of the first and last words may be contained
3186          * within the block range.  if this is the case, we'll work against
3187          * those words (i.e. partial first and/or last) on an individual basis
3188          * (a single pass), allocating the bits of interest by hand and
3189          * updating the leaf corresponding to the dmap word. a single pass
3190          * will be used for all dmap words fully contained within the
3191          * specified range.  within this pass, the bits of all fully contained
3192          * dmap words will be marked as free in a single shot and the leaves
3193          * will be updated. a single leaf may describe the free space of
3194          * multiple dmap words, so we may update only a subset of the actual
3195          * leaves corresponding to the dmap words of the block range.
3196          */
3197         for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
3198                 /* determine the bit number within the word and
3199                  * the number of bits within the word.
3200                  */
3201                 wbitno = dbitno & (DBWORD - 1);
3202                 nb = min(rembits, DBWORD - wbitno);
3203 
3204                 /* check if only part of a word is to be allocated.
3205                  */
3206                 if (nb < DBWORD) {
3207                         /* allocate (set to 1) the appropriate bits within
3208                          * this dmap word.
3209                          */
3210                         dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
3211                                                       >> wbitno);
3212 
3213                         word++;
3214                 } else {
3215                         /* one or more dmap words are fully contained
3216                          * within the block range.  determine how many
3217                          * words and allocate (set to 1) the bits of these
3218                          * words.
3219                          */
3220                         nwords = rembits >> L2DBWORD;
3221                         memset(&dp->wmap[word], (int) ONES, nwords * 4);
3222 
3223                         /* determine how many bits */
3224                         nb = nwords << L2DBWORD;
3225                         word += nwords;
3226                 }
3227         }
3228 
3229         /* update the free count for this dmap */
3230         le32_add_cpu(&dp->nfree, -nblocks);
3231 
3232         /* reconstruct summary tree */
3233         dbInitDmapTree(dp);
3234 
3235         BMAP_LOCK(bmp);
3236 
3237         /* if this allocation group is completely free,
3238          * update the highest active allocation group number
3239          * if this allocation group is the new max.
3240          */
3241         agno = blkno >> bmp->db_agl2size;
3242         if (agno > bmp->db_maxag)
3243                 bmp->db_maxag = agno;
3244 
3245         /* update the free count for the allocation group and map */
3246         bmp->db_agfree[agno] -= nblocks;
3247         bmp->db_nfree -= nblocks;
3248 
3249         BMAP_UNLOCK(bmp);
3250 
3251         /* if the root has not changed, done. */
3252         if (tp->stree[ROOT] == oldroot)
3253                 return (0);
3254 
3255         /* root changed. bubble the change up to the dmap control pages.
3256          * if the adjustment of the upper level control pages fails,
3257          * backout the bit allocation (thus making everything consistent).
3258          */
3259         if ((rc = dbAdjCtl(bmp, blkno, tp->stree[ROOT], 1, 0)))
3260                 dbFreeBits(bmp, dp, blkno, nblocks);
3261 
3262         return (rc);
3263 }
3264 
3265 
3266 /*
3267  * NAME:        dbExtendFS()
3268  *
3269  * FUNCTION:    extend bmap from blkno for nblocks;
3270  *              dbExtendFS() updates bmap ready for dbAllocBottomUp();
3271  *
3272  * L2
3273  *  |
3274  *   L1---------------------------------L1
3275  *    |                                  |
3276  *     L0---------L0---------L0           L0---------L0---------L0
3277  *      |          |          |            |          |          |
3278  *       d0,...,dn  d0,...,dn  d0,...,dn    d0,...,dn  d0,...,dn  d0,.,dm;
3279  * L2L1L0d0,...,dnL0d0,...,dnL0d0,...,dnL1L0d0,...,dnL0d0,...,dnL0d0,..dm
3280  *
3281  * <---old---><----------------------------extend----------------------->
3282  */
3283 int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks)
3284 {
3285         struct jfs_sb_info *sbi = JFS_SBI(ipbmap->i_sb);
3286         int nbperpage = sbi->nbperpage;
3287         int i, i0 = true, j, j0 = true, k, n;
3288         s64 newsize;
3289         s64 p;
3290         struct metapage *mp, *l2mp, *l1mp = NULL, *l0mp = NULL;
3291         struct dmapctl *l2dcp, *l1dcp, *l0dcp;
3292         struct dmap *dp;
3293         s8 *l0leaf, *l1leaf, *l2leaf;
3294         struct bmap *bmp = sbi->bmap;
3295         int agno, l2agsize, oldl2agsize;
3296         s64 ag_rem;
3297 
3298         newsize = blkno + nblocks;
3299 
3300         jfs_info("dbExtendFS: blkno:%Ld nblocks:%Ld newsize:%Ld",
3301                  (long long) blkno, (long long) nblocks, (long long) newsize);
3302 
3303         /*
3304          *      initialize bmap control page.
3305          *
3306          * all the data in bmap control page should exclude
3307          * the mkfs hidden dmap page.
3308          */
3309 
3310         /* update mapsize */
3311         bmp->db_mapsize = newsize;
3312         bmp->db_maxlevel = BMAPSZTOLEV(bmp->db_mapsize);
3313 
3314         /* compute new AG size */
3315         l2agsize = dbGetL2AGSize(newsize);
3316         oldl2agsize = bmp->db_agl2size;
3317 
3318         bmp->db_agl2size = l2agsize;
3319         bmp->db_agsize = 1 << l2agsize;
3320 
3321         /* compute new number of AG */
3322         agno = bmp->db_numag;
3323         bmp->db_numag = newsize >> l2agsize;
3324         bmp->db_numag += ((u32) newsize % (u32) bmp->db_agsize) ? 1 : 0;
3325 
3326         /*
3327          *      reconfigure db_agfree[]
3328          * from old AG configuration to new AG configuration;
3329          *
3330          * coalesce contiguous k (newAGSize/oldAGSize) AGs;
3331          * i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
3332          * note: new AG size = old AG size * (2**x).
3333          */
3334         if (l2agsize == oldl2agsize)
3335                 goto extend;
3336         k = 1 << (l2agsize - oldl2agsize);
3337         ag_rem = bmp->db_agfree[0];     /* save agfree[0] */
3338         for (i = 0, n = 0; i < agno; n++) {
3339                 bmp->db_agfree[n] = 0;  /* init collection point */
3340 
3341                 /* coalesce contiguous k AGs; */
3342                 for (j = 0; j < k && i < agno; j++, i++) {
3343                         /* merge AGi to AGn */
3344                         bmp->db_agfree[n] += bmp->db_agfree[i];
3345                 }
3346         }
3347         bmp->db_agfree[0] += ag_rem;    /* restore agfree[0] */
3348 
3349         for (; n < MAXAG; n++)
3350                 bmp->db_agfree[n] = 0;
3351 
3352         /*
3353          * update highest active ag number
3354          */
3355 
3356         bmp->db_maxag = bmp->db_maxag / k;
3357 
3358         /*
3359          *      extend bmap
3360          *
3361          * update bit maps and corresponding level control pages;
3362          * global control page db_nfree, db_agfree[agno], db_maxfreebud;
3363          */
3364       extend:
3365         /* get L2 page */
3366         p = BMAPBLKNO + nbperpage;      /* L2 page */
3367         l2mp = read_metapage(ipbmap, p, PSIZE, 0);
3368         if (!l2mp) {
3369                 jfs_error(ipbmap->i_sb, "dbExtendFS: L2 page could not be read");
3370                 return -EIO;
3371         }
3372         l2dcp = (struct dmapctl *) l2mp->data;
3373 
3374         /* compute start L1 */
3375         k = blkno >> L2MAXL1SIZE;
3376         l2leaf = l2dcp->stree + CTLLEAFIND + k;
3377         p = BLKTOL1(blkno, sbi->l2nbperpage);   /* L1 page */
3378 
3379         /*
3380          * extend each L1 in L2
3381          */
3382         for (; k < LPERCTL; k++, p += nbperpage) {
3383                 /* get L1 page */
3384                 if (j0) {
3385                         /* read in L1 page: (blkno & (MAXL1SIZE - 1)) */
3386                         l1mp = read_metapage(ipbmap, p, PSIZE, 0);
3387                         if (l1mp == NULL)
3388                                 goto errout;
3389                         l1dcp = (struct dmapctl *) l1mp->data;
3390 
3391                         /* compute start L0 */
3392                         j = (blkno & (MAXL1SIZE - 1)) >> L2MAXL0SIZE;
3393                         l1leaf = l1dcp->stree + CTLLEAFIND + j;
3394                         p = BLKTOL0(blkno, sbi->l2nbperpage);
3395                         j0 = false;
3396                 } else {
3397                         /* assign/init L1 page */
3398                         l1mp = get_metapage(ipbmap, p, PSIZE, 0);
3399                         if (l1mp == NULL)
3400                                 goto errout;
3401 
3402                         l1dcp = (struct dmapctl *) l1mp->data;
3403 
3404                         /* compute start L0 */
3405                         j = 0;
3406                         l1leaf = l1dcp->stree + CTLLEAFIND;
3407                         p += nbperpage; /* 1st L0 of L1.k */
3408                 }
3409 
3410                 /*
3411                  * extend each L0 in L1
3412                  */
3413                 for (; j < LPERCTL; j++) {
3414                         /* get L0 page */
3415                         if (i0) {
3416                                 /* read in L0 page: (blkno & (MAXL0SIZE - 1)) */
3417 
3418                                 l0mp = read_metapage(ipbmap, p, PSIZE, 0);
3419                                 if (l0mp == NULL)
3420                                         goto errout;
3421                                 l0dcp = (struct dmapctl *) l0mp->data;
3422 
3423                                 /* compute start dmap */
3424                                 i = (blkno & (MAXL0SIZE - 1)) >>
3425                                     L2BPERDMAP;
3426                                 l0leaf = l0dcp->stree + CTLLEAFIND + i;
3427                                 p = BLKTODMAP(blkno,
3428                                               sbi->l2nbperpage);
3429                                 i0 = false;
3430                         } else {
3431                                 /* assign/init L0 page */
3432                                 l0mp = get_metapage(ipbmap, p, PSIZE, 0);
3433                                 if (l0mp == NULL)
3434                                         goto errout;
3435 
3436                                 l0dcp = (struct dmapctl *) l0mp->data;
3437 
3438                                 /* compute start dmap */
3439                                 i = 0;
3440                                 l0leaf = l0dcp->stree + CTLLEAFIND;
3441                                 p += nbperpage; /* 1st dmap of L0.j */
3442                         }
3443 
3444                         /*
3445                          * extend each dmap in L0
3446                          */
3447                         for (; i < LPERCTL; i++) {
3448                                 /*
3449                                  * reconstruct the dmap page, and
3450                                  * initialize corresponding parent L0 leaf
3451                                  */
3452                                 if ((n = blkno & (BPERDMAP - 1))) {
3453                                         /* read in dmap page: */
3454                                         mp = read_metapage(ipbmap, p,
3455                                                            PSIZE, 0);
3456                                         if (mp == NULL)
3457                                                 goto errout;
3458                                         n = min(nblocks, (s64)BPERDMAP - n);
3459                                 } else {
3460                                         /* assign/init dmap page */
3461                                         mp = read_metapage(ipbmap, p,
3462                                                            PSIZE, 0);
3463                                         if (mp == NULL)
3464                                                 goto errout;
3465 
3466                                         n = min(nblocks, (s64)BPERDMAP);
3467                                 }
3468 
3469                                 dp = (struct dmap *) mp->data;
3470                                 *l0leaf = dbInitDmap(dp, blkno, n);
3471 
3472                                 bmp->db_nfree += n;
3473                                 agno = le64_to_cpu(dp->start) >> l2agsize;
3474                                 bmp->db_agfree[agno] += n;
3475 
3476                                 write_metapage(mp);
3477 
3478                                 l0leaf++;
3479                                 p += nbperpage;
3480 
3481                                 blkno += n;
3482                                 nblocks -= n;
3483                                 if (nblocks == 0)
3484                                         break;
3485                         }       /* for each dmap in a L0 */
3486 
3487                         /*
3488                          * build current L0 page from its leaves, and
3489                          * initialize corresponding parent L1 leaf
3490                          */
3491                         *l1leaf = dbInitDmapCtl(l0dcp, 0, ++i);
3492                         write_metapage(l0mp);
3493                         l0mp = NULL;
3494 
3495                         if (nblocks)
3496                                 l1leaf++;       /* continue for next L0 */
3497                         else {
3498                                 /* more than 1 L0 ? */
3499                                 if (j > 0)
3500                                         break;  /* build L1 page */
3501                                 else {
3502                                         /* summarize in global bmap page */
3503                                         bmp->db_maxfreebud = *l1leaf;
3504                                         release_metapage(l1mp);
3505                                         release_metapage(l2mp);
3506                                         goto finalize;
3507                                 }
3508                         }
3509                 }               /* for each L0 in a L1 */
3510 
3511                 /*
3512                  * build current L1 page from its leaves, and
3513                  * initialize corresponding parent L2 leaf
3514                  */
3515                 *l2leaf = dbInitDmapCtl(l1dcp, 1, ++j);
3516                 write_metapage(l1mp);
3517                 l1mp = NULL;
3518 
3519                 if (nblocks)
3520                         l2leaf++;       /* continue for next L1 */
3521                 else {
3522                         /* more than 1 L1 ? */
3523                         if (k > 0)
3524                                 break;  /* build L2 page */
3525                         else {
3526                                 /* summarize in global bmap page */
3527                                 bmp->db_maxfreebud = *l2leaf;
3528                                 release_metapage(l2mp);
3529                                 goto finalize;
3530                         }
3531                 }
3532         }                       /* for each L1 in a L2 */
3533 
3534         jfs_error(ipbmap->i_sb,
3535                   "dbExtendFS: function has not returned as expected");
3536 errout:
3537         if (l0mp)
3538                 release_metapage(l0mp);
3539         if (l1mp)
3540                 release_metapage(l1mp);
3541         release_metapage(l2mp);
3542         return -EIO;
3543 
3544         /*
3545          *      finalize bmap control page
3546          */
3547 finalize:
3548 
3549         return 0;
3550 }
3551 
3552 
3553 /*
3554  *      dbFinalizeBmap()
3555  */
3556 void dbFinalizeBmap(struct inode *ipbmap)
3557 {
3558         struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
3559         int actags, inactags, l2nl;
3560         s64 ag_rem, actfree, inactfree, avgfree;
3561         int i, n;
3562 
3563         /*
3564          *      finalize bmap control page
3565          */
3566 //finalize:
3567         /*
3568          * compute db_agpref: preferred ag to allocate from
3569          * (the leftmost ag with average free space in it);
3570          */
3571 //agpref:
3572         /* get the number of active ags and inacitve ags */
3573         actags = bmp->db_maxag + 1;
3574         inactags = bmp->db_numag - actags;
3575         ag_rem = bmp->db_mapsize & (bmp->db_agsize - 1);        /* ??? */
3576 
3577         /* determine how many blocks are in the inactive allocation
3578          * groups. in doing this, we must account for the fact that
3579          * the rightmost group might be a partial group (i.e. file
3580          * system size is not a multiple of the group size).
3581          */
3582         inactfree = (inactags && ag_rem) ?
3583             ((inactags - 1) << bmp->db_agl2size) + ag_rem
3584             : inactags << bmp->db_agl2size;
3585 
3586         /* determine how many free blocks are in the active
3587          * allocation groups plus the average number of free blocks
3588          * within the active ags.
3589          */
3590         actfree = bmp->db_nfree - inactfree;
3591         avgfree = (u32) actfree / (u32) actags;
3592 
3593         /* if the preferred allocation group has not average free space.
3594          * re-establish the preferred group as the leftmost
3595          * group with average free space.
3596          */
3597         if (bmp->db_agfree[bmp->db_agpref] < avgfree) {
3598                 for (bmp->db_agpref = 0; bmp->db_agpref < actags;
3599                      bmp->db_agpref++) {
3600                         if (bmp->db_agfree[bmp->db_agpref] >= avgfree)
3601                                 break;
3602                 }
3603                 if (bmp->db_agpref >= bmp->db_numag) {
3604                         jfs_error(ipbmap->i_sb,
3605                                   "cannot find ag with average freespace");
3606                 }
3607         }
3608 
3609         /*
3610          * compute db_aglevel, db_agheight, db_width, db_agstart:
3611          * an ag is covered in aglevel dmapctl summary tree,
3612          * at agheight level height (from leaf) with agwidth number of nodes
3613          * each, which starts at agstart index node of the smmary tree node
3614          * array;
3615          */
3616         bmp->db_aglevel = BMAPSZTOLEV(bmp->db_agsize);
3617         l2nl =
3618             bmp->db_agl2size - (L2BPERDMAP + bmp->db_aglevel * L2LPERCTL);
3619         bmp->db_agheight = l2nl >> 1;
3620         bmp->db_agwidth = 1 << (l2nl - (bmp->db_agheight << 1));
3621         for (i = 5 - bmp->db_agheight, bmp->db_agstart = 0, n = 1; i > 0;
3622              i--) {
3623                 bmp->db_agstart += n;
3624                 n <<= 2;
3625         }
3626 
3627 }
3628 
3629 
3630 /*
3631  * NAME:        dbInitDmap()/ujfs_idmap_page()
3632  *
3633  * FUNCTION:    initialize working/persistent bitmap of the dmap page
3634  *              for the specified number of blocks:
3635  *
3636  *              at entry, the bitmaps had been initialized as free (ZEROS);
3637  *              The number of blocks will only account for the actually
3638  *              existing blocks. Blocks which don't actually exist in
3639  *              the aggregate will be marked as allocated (ONES);
3640  *
3641  * PARAMETERS:
3642  *      dp      - pointer to page of map
3643  *      nblocks - number of blocks this page
3644  *
3645  * RETURNS: NONE
3646  */
3647 static int dbInitDmap(struct dmap * dp, s64 Blkno, int nblocks)
3648 {
3649         int blkno, w, b, r, nw, nb, i;
3650 
3651         /* starting block number within the dmap */
3652         blkno = Blkno & (BPERDMAP - 1);
3653 
3654         if (blkno == 0) {
3655                 dp->nblocks = dp->nfree = cpu_to_le32(nblocks);
3656                 dp->start = cpu_to_le64(Blkno);
3657 
3658                 if (nblocks == BPERDMAP) {
3659                         memset(&dp->wmap[0], 0, LPERDMAP * 4);
3660                         memset(&dp->pmap[0], 0, LPERDMAP * 4);
3661                         goto initTree;
3662                 }
3663         } else {
3664                 le32_add_cpu(&dp->nblocks, nblocks);
3665                 le32_add_cpu(&dp->nfree, nblocks);
3666         }
3667 
3668         /* word number containing start block number */
3669         w = blkno >> L2DBWORD;
3670 
3671         /*
3672          * free the bits corresponding to the block range (ZEROS):
3673          * note: not all bits of the first and last words may be contained
3674          * within the block range.
3675          */
3676         for (r = nblocks; r > 0; r -= nb, blkno += nb) {
3677                 /* number of bits preceding range to be freed in the word */
3678                 b = blkno & (DBWORD - 1);
3679                 /* number of bits to free in the word */
3680                 nb = min(r, DBWORD - b);
3681 
3682                 /* is partial word to be freed ? */
3683                 if (nb < DBWORD) {
3684                         /* free (set to 0) from the bitmap word */
3685                         dp->wmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3686                                                      >> b));
3687                         dp->pmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3688                                                      >> b));
3689 
3690                         /* skip the word freed */
3691                         w++;
3692                 } else {
3693                         /* free (set to 0) contiguous bitmap words */
3694                         nw = r >> L2DBWORD;
3695                         memset(&dp->wmap[w], 0, nw * 4);
3696                         memset(&dp->pmap[w], 0, nw * 4);
3697 
3698                         /* skip the words freed */
3699                         nb = nw << L2DBWORD;
3700                         w += nw;
3701                 }
3702         }
3703 
3704         /*
3705          * mark bits following the range to be freed (non-existing
3706          * blocks) as allocated (ONES)
3707          */
3708 
3709         if (blkno == BPERDMAP)
3710                 goto initTree;
3711 
3712         /* the first word beyond the end of existing blocks */
3713         w = blkno >> L2DBWORD;
3714 
3715         /* does nblocks fall on a 32-bit boundary ? */
3716         b = blkno & (DBWORD - 1);
3717         if (b) {
3718                 /* mark a partial word allocated */
3719                 dp->wmap[w] = dp->pmap[w] = cpu_to_le32(ONES >> b);
3720                 w++;
3721         }
3722 
3723         /* set the rest of the words in the page to allocated (ONES) */
3724         for (i = w; i < LPERDMAP; i++)
3725                 dp->pmap[i] = dp->wmap[i] = cpu_to_le32(ONES);
3726 
3727         /*
3728          * init tree
3729          */
3730       initTree:
3731         return (dbInitDmapTree(dp));
3732 }
3733 
3734 
3735 /*
3736  * NAME:        dbInitDmapTree()/ujfs_complete_dmap()
3737  *
3738  * FUNCTION:    initialize summary tree of the specified dmap:
3739  *
3740  *              at entry, bitmap of the dmap has been initialized;
3741  *
3742  * PARAMETERS:
3743  *      dp      - dmap to complete
3744  *      blkno   - starting block number for this dmap
3745  *      treemax - will be filled in with max free for this dmap
3746  *
3747  * RETURNS:     max free string at the root of the tree
3748  */
3749 static int dbInitDmapTree(struct dmap * dp)
3750 {
3751         struct dmaptree *tp;
3752         s8 *cp;
3753         int i;
3754 
3755         /* init fixed info of tree */
3756         tp = &dp->tree;
3757         tp->nleafs = cpu_to_le32(LPERDMAP);
3758         tp->l2nleafs = cpu_to_le32(L2LPERDMAP);
3759         tp->leafidx = cpu_to_le32(LEAFIND);
3760         tp->height = cpu_to_le32(4);
3761         tp->budmin = BUDMIN;
3762 
3763         /* init each leaf from corresponding wmap word:
3764          * note: leaf is set to NOFREE(-1) if all blocks of corresponding
3765          * bitmap word are allocated.
3766          */
3767         cp = tp->stree + le32_to_cpu(tp->leafidx);
3768         for (i = 0; i < LPERDMAP; i++)
3769                 *cp++ = dbMaxBud((u8 *) & dp->wmap[i]);
3770 
3771         /* build the dmap's binary buddy summary tree */
3772         return (dbInitTree(tp));
3773 }
3774 
3775 
3776 /*
3777  * NAME:        dbInitTree()/ujfs_adjtree()
3778  *
3779  * FUNCTION:    initialize binary buddy summary tree of a dmap or dmapctl.
3780  *
3781  *              at entry, the leaves of the tree has been initialized
3782  *              from corresponding bitmap word or root of summary tree
3783  *              of the child control page;
3784  *              configure binary buddy system at the leaf level, then
3785  *              bubble up the values of the leaf nodes up the tree.
3786  *
3787  * PARAMETERS:
3788  *      cp      - Pointer to the root of the tree
3789  *      l2leaves- Number of leaf nodes as a power of 2
3790  *      l2min   - Number of blocks that can be covered by a leaf
3791  *                as a power of 2
3792  *
3793  * RETURNS: max free string at the root of the tree
3794  */
3795 static int dbInitTree(struct dmaptree * dtp)
3796 {
3797         int l2max, l2free, bsize, nextb, i;
3798         int child, parent, nparent;
3799         s8 *tp, *cp, *cp1;
3800 
3801         tp = dtp->stree;
3802 
3803         /* Determine the maximum free string possible for the leaves */
3804         l2max = le32_to_cpu(dtp->l2nleafs) + dtp->budmin;
3805 
3806         /*
3807          * configure the leaf levevl into binary buddy system
3808          *
3809          * Try to combine buddies starting with a buddy size of 1
3810          * (i.e. two leaves). At a buddy size of 1 two buddy leaves
3811          * can be combined if both buddies have a maximum free of l2min;
3812          * the combination will result in the left-most buddy leaf having
3813          * a maximum free of l2min+1.
3814          * After processing all buddies for a given size, process buddies
3815          * at the next higher buddy size (i.e. current size * 2) and
3816          * the next maximum free (current free + 1).
3817          * This continues until the maximum possible buddy combination
3818          * yields maximum free.
3819          */
3820         for (l2free = dtp->budmin, bsize = 1; l2free < l2max;
3821              l2free++, bsize = nextb) {
3822                 /* get next buddy size == current buddy pair size */
3823                 nextb = bsize << 1;
3824 
3825                 /* scan each adjacent buddy pair at current buddy size */
3826                 for (i = 0, cp = tp + le32_to_cpu(dtp->leafidx);
3827                      i < le32_to_cpu(dtp->nleafs);
3828                      i += nextb, cp += nextb) {
3829                         /* coalesce if both adjacent buddies are max free */
3830                         if (*cp == l2free && *(cp + bsize) == l2free) {
3831                                 *cp = l2free + 1;       /* left take right */
3832                                 *(cp + bsize) = -1;     /* right give left */
3833                         }
3834                 }
3835         }
3836 
3837         /*
3838          * bubble summary information of leaves up the tree.
3839          *
3840          * Starting at the leaf node level, the four nodes described by
3841          * the higher level parent node are compared for a maximum free and
3842          * this maximum becomes the value of the parent node.
3843          * when all lower level nodes are processed in this fashion then
3844          * move up to the next level (parent becomes a lower level node) and
3845          * continue the process for that level.
3846          */
3847         for (child = le32_to_cpu(dtp->leafidx),
3848              nparent = le32_to_cpu(dtp->nleafs) >> 2;
3849              nparent > 0; nparent >>= 2, child = parent) {
3850                 /* get index of 1st node of parent level */
3851                 parent = (child - 1) >> 2;
3852 
3853                 /* set the value of the parent node as the maximum
3854                  * of the four nodes of the current level.
3855                  */
3856                 for (i = 0, cp = tp + child, cp1 = tp + parent;
3857                      i < nparent; i++, cp += 4, cp1++)
3858                         *cp1 = TREEMAX(cp);
3859         }
3860 
3861         return (*tp);
3862 }
3863 
3864 
3865 /*
3866  *      dbInitDmapCtl()
3867  *
3868  * function: initialize dmapctl page
3869  */
3870 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i)
3871 {                               /* start leaf index not covered by range */
3872         s8 *cp;
3873 
3874         dcp->nleafs = cpu_to_le32(LPERCTL);
3875         dcp->l2nleafs = cpu_to_le32(L2LPERCTL);
3876         dcp->leafidx = cpu_to_le32(CTLLEAFIND);
3877         dcp->height = cpu_to_le32(5);
3878         dcp->budmin = L2BPERDMAP + L2LPERCTL * level;
3879 
3880         /*
3881          * initialize the leaves of current level that were not covered
3882          * by the specified input block range (i.e. the leaves have no
3883          * low level dmapctl or dmap).
3884          */
3885         cp = &dcp->stree[CTLLEAFIND + i];
3886         for (; i < LPERCTL; i++)
3887                 *cp++ = NOFREE;
3888 
3889         /* build the dmap's binary buddy summary tree */
3890         return (dbInitTree((struct dmaptree *) dcp));
3891 }
3892 
3893 
3894 /*
3895  * NAME:        dbGetL2AGSize()/ujfs_getagl2size()
3896  *
3897  * FUNCTION:    Determine log2(allocation group size) from aggregate size
3898  *
3899  * PARAMETERS:
3900  *      nblocks - Number of blocks in aggregate
3901  *
3902  * RETURNS: log2(allocation group size) in aggregate blocks
3903  */
3904 static int dbGetL2AGSize(s64 nblocks)
3905 {
3906         s64 sz;
3907         s64 m;
3908         int l2sz;
3909 
3910         if (nblocks < BPERDMAP * MAXAG)
3911                 return (L2BPERDMAP);
3912 
3913         /* round up aggregate size to power of 2 */
3914         m = ((u64) 1 << (64 - 1));
3915         for (l2sz = 64; l2sz >= 0; l2sz--, m >>= 1) {
3916                 if (m & nblocks)
3917                         break;
3918         }
3919 
3920         sz = (s64) 1 << l2sz;
3921         if (sz < nblocks)
3922                 l2sz += 1;
3923 
3924         /* agsize = roundupSize/max_number_of_ag */
3925         return (l2sz - L2MAXAG);
3926 }
3927 
3928 
3929 /*
3930  * NAME:        dbMapFileSizeToMapSize()
3931  *
3932  * FUNCTION:    compute number of blocks the block allocation map file
3933  *              can cover from the map file size;
3934  *
3935  * RETURNS:     Number of blocks which can be covered by this block map file;
3936  */
3937 
3938 /*
3939  * maximum number of map pages at each level including control pages
3940  */
3941 #define MAXL0PAGES      (1 + LPERCTL)
3942 #define MAXL1PAGES      (1 + LPERCTL * MAXL0PAGES)
3943 #define MAXL2PAGES      (1 + LPERCTL * MAXL1PAGES)
3944 
3945 /*
3946  * convert number of map pages to the zero origin top dmapctl level
3947  */
3948 #define BMAPPGTOLEV(npages)     \
3949         (((npages) <= 3 + MAXL0PAGES) ? 0 : \
3950          ((npages) <= 2 + MAXL1PAGES) ? 1 : 2)
3951 
3952 s64 dbMapFileSizeToMapSize(struct inode * ipbmap)
3953 {
3954         struct super_block *sb = ipbmap->i_sb;
3955         s64 nblocks;
3956         s64 npages, ndmaps;
3957         int level, i;
3958         int complete, factor;
3959 
3960         nblocks = ipbmap->i_size >> JFS_SBI(sb)->l2bsize;
3961         npages = nblocks >> JFS_SBI(sb)->l2nbperpage;
3962         level = BMAPPGTOLEV(npages);
3963 
3964         /* At each level, accumulate the number of dmap pages covered by
3965          * the number of full child levels below it;
3966          * repeat for the last incomplete child level.
3967          */
3968         ndmaps = 0;
3969         npages--;               /* skip the first global control page */
3970         /* skip higher level control pages above top level covered by map */
3971         npages -= (2 - level);
3972         npages--;               /* skip top level's control page */
3973         for (i = level; i >= 0; i--) {
3974                 factor =
3975                     (i == 2) ? MAXL1PAGES : ((i == 1) ? MAXL0PAGES : 1);
3976                 complete = (u32) npages / factor;
3977                 ndmaps += complete * ((i == 2) ? LPERCTL * LPERCTL :
3978                                       ((i == 1) ? LPERCTL : 1));
3979 
3980                 /* pages in last/incomplete child */
3981                 npages = (u32) npages % factor;
3982                 /* skip incomplete child's level control page */
3983                 npages--;
3984         }
3985 
3986         /* convert the number of dmaps into the number of blocks
3987          * which can be covered by the dmaps;
3988          */
3989         nblocks = ndmaps << L2BPERDMAP;
3990 
3991         return (nblocks);
3992 }
3993 

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