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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  *   Portions Copyright (C) Tino Reichardt, 2012
  4  *
  5  *   This program is free software;  you can redistribute it and/or modify
  6  *   it under the terms of the GNU General Public License as published by
  7  *   the Free Software Foundation; either version 2 of the License, or
  8  *   (at your option) any later version.
  9  *
 10  *   This program is distributed in the hope that it will be useful,
 11  *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 13  *   the GNU General Public License for more details.
 14  *
 15  *   You should have received a copy of the GNU General Public License
 16  *   along with this program;  if not, write to the Free Software
 17  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 18  */
 19 
 20 #include <linux/fs.h>
 21 #include <linux/slab.h>
 22 #include "jfs_incore.h"
 23 #include "jfs_superblock.h"
 24 #include "jfs_dmap.h"
 25 #include "jfs_imap.h"
 26 #include "jfs_lock.h"
 27 #include "jfs_metapage.h"
 28 #include "jfs_debug.h"
 29 #include "jfs_discard.h"
 30 
 31 /*
 32  *      SERIALIZATION of the Block Allocation Map.
 33  *
 34  *      the working state of the block allocation map is accessed in
 35  *      two directions:
 36  *
 37  *      1) allocation and free requests that start at the dmap
 38  *         level and move up through the dmap control pages (i.e.
 39  *         the vast majority of requests).
 40  *
 41  *      2) allocation requests that start at dmap control page
 42  *         level and work down towards the dmaps.
 43  *
 44  *      the serialization scheme used here is as follows.
 45  *
 46  *      requests which start at the bottom are serialized against each
 47  *      other through buffers and each requests holds onto its buffers
 48  *      as it works it way up from a single dmap to the required level
 49  *      of dmap control page.
 50  *      requests that start at the top are serialized against each other
 51  *      and request that start from the bottom by the multiple read/single
 52  *      write inode lock of the bmap inode. requests starting at the top
 53  *      take this lock in write mode while request starting at the bottom
 54  *      take the lock in read mode.  a single top-down request may proceed
 55  *      exclusively while multiple bottoms-up requests may proceed
 56  *      simultaneously (under the protection of busy buffers).
 57  *
 58  *      in addition to information found in dmaps and dmap control pages,
 59  *      the working state of the block allocation map also includes read/
 60  *      write information maintained in the bmap descriptor (i.e. total
 61  *      free block count, allocation group level free block counts).
 62  *      a single exclusive lock (BMAP_LOCK) is used to guard this information
 63  *      in the face of multiple-bottoms up requests.
 64  *      (lock ordering: IREAD_LOCK, BMAP_LOCK);
 65  *
 66  *      accesses to the persistent state of the block allocation map (limited
 67  *      to the persistent bitmaps in dmaps) is guarded by (busy) buffers.
 68  */
 69 
 70 #define BMAP_LOCK_INIT(bmp)     mutex_init(&bmp->db_bmaplock)
 71 #define BMAP_LOCK(bmp)          mutex_lock(&bmp->db_bmaplock)
 72 #define BMAP_UNLOCK(bmp)        mutex_unlock(&bmp->db_bmaplock)
 73 
 74 /*
 75  * forward references
 76  */
 77 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 78                         int nblocks);
 79 static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval);
 80 static int dbBackSplit(dmtree_t * tp, int leafno);
 81 static int dbJoin(dmtree_t * tp, int leafno, int newval);
 82 static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
 83 static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
 84                     int level);
 85 static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results);
 86 static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
 87                        int nblocks);
 88 static int dbAllocNear(struct bmap * bmp, struct dmap * dp, s64 blkno,
 89                        int nblocks,
 90                        int l2nb, s64 * results);
 91 static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
 92                        int nblocks);
 93 static int dbAllocDmapLev(struct bmap * bmp, struct dmap * dp, int nblocks,
 94                           int l2nb,
 95                           s64 * results);
 96 static int dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb,
 97                      s64 * results);
 98 static int dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno,
 99                       s64 * results);
100 static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks);
101 static int dbFindBits(u32 word, int l2nb);
102 static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno);
103 static int dbFindLeaf(dmtree_t * tp, int l2nb, int *leafidx);
104 static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
105                       int nblocks);
106 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
107                       int nblocks);
108 static int dbMaxBud(u8 * cp);
109 static int blkstol2(s64 nb);
110 
111 static int cntlz(u32 value);
112 static int cnttz(u32 word);
113 
114 static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
115                          int nblocks);
116 static int dbInitDmap(struct dmap * dp, s64 blkno, int nblocks);
117 static int dbInitDmapTree(struct dmap * dp);
118 static int dbInitTree(struct dmaptree * dtp);
119 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i);
120 static int dbGetL2AGSize(s64 nblocks);
121 
122 /*
123  *      buddy table
124  *
125  * table used for determining buddy sizes within characters of
126  * dmap bitmap words.  the characters themselves serve as indexes
127  * into the table, with the table elements yielding the maximum
128  * binary buddy of free bits within the character.
129  */
130 static const s8 budtab[256] = {
131         3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
139         2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
143         2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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, 0,
146         2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -1
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  * NAME:        dbFree()
315  *
316  * FUNCTION:    free the specified block range from the working block
317  *              allocation map.
318  *
319  *              the blocks will be free from the working map one dmap
320  *              at a time.
321  *
322  * PARAMETERS:
323  *      ip      - pointer to in-core inode;
324  *      blkno   - starting block number to be freed.
325  *      nblocks - number of blocks to be freed.
326  *
327  * RETURN VALUES:
328  *      0       - success
329  *      -EIO    - i/o error
330  */
331 int dbFree(struct inode *ip, s64 blkno, s64 nblocks)
332 {
333         struct metapage *mp;
334         struct dmap *dp;
335         int nb, rc;
336         s64 lblkno, rem;
337         struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
338         struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
339         struct super_block *sb = ipbmap->i_sb;
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, "block to be freed is outside the map\n");
350                 return -EIO;
351         }
352 
353         /**
354          * TRIM the blocks, when mounted with discard option
355          */
356         if (JFS_SBI(sb)->flag & JFS_DISCARD)
357                 if (JFS_SBI(sb)->minblks_trim <= nblocks)
358                         jfs_issue_discard(ipbmap, blkno, nblocks);
359 
360         /*
361          * free the blocks a dmap at a time.
362          */
363         mp = NULL;
364         for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
365                 /* release previous dmap if any */
366                 if (mp) {
367                         write_metapage(mp);
368                 }
369 
370                 /* get the buffer for the current dmap. */
371                 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
372                 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
373                 if (mp == NULL) {
374                         IREAD_UNLOCK(ipbmap);
375                         return -EIO;
376                 }
377                 dp = (struct dmap *) mp->data;
378 
379                 /* determine the number of blocks to be freed from
380                  * this dmap.
381                  */
382                 nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
383 
384                 /* free the blocks. */
385                 if ((rc = dbFreeDmap(bmp, dp, blkno, nb))) {
386                         jfs_error(ip->i_sb, "error in block map\n");
387                         release_metapage(mp);
388                         IREAD_UNLOCK(ipbmap);
389                         return (rc);
390                 }
391         }
392 
393         /* write the last buffer. */
394         write_metapage(mp);
395 
396         IREAD_UNLOCK(ipbmap);
397 
398         return (0);
399 }
400 
401 
402 /*
403  * NAME:        dbUpdatePMap()
404  *
405  * FUNCTION:    update the allocation state (free or allocate) of the
406  *              specified block range in the persistent block allocation map.
407  *
408  *              the blocks will be updated in the persistent map one
409  *              dmap at a time.
410  *
411  * PARAMETERS:
412  *      ipbmap  - pointer to in-core inode for the block map.
413  *      free    - 'true' if block range is to be freed from the persistent
414  *                map; 'false' if it is to be allocated.
415  *      blkno   - starting block number of the range.
416  *      nblocks - number of contiguous blocks in the range.
417  *      tblk    - transaction block;
418  *
419  * RETURN VALUES:
420  *      0       - success
421  *      -EIO    - i/o error
422  */
423 int
424 dbUpdatePMap(struct inode *ipbmap,
425              int free, s64 blkno, s64 nblocks, struct tblock * tblk)
426 {
427         int nblks, dbitno, wbitno, rbits;
428         int word, nbits, nwords;
429         struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
430         s64 lblkno, rem, lastlblkno;
431         u32 mask;
432         struct dmap *dp;
433         struct metapage *mp;
434         struct jfs_log *log;
435         int lsn, difft, diffp;
436         unsigned long flags;
437 
438         /* the blocks better be within the mapsize. */
439         if (blkno + nblocks > bmp->db_mapsize) {
440                 printk(KERN_ERR "blkno = %Lx, nblocks = %Lx\n",
441                        (unsigned long long) blkno,
442                        (unsigned long long) nblocks);
443                 jfs_error(ipbmap->i_sb, "blocks are outside the map\n");
444                 return -EIO;
445         }
446 
447         /* compute delta of transaction lsn from log syncpt */
448         lsn = tblk->lsn;
449         log = (struct jfs_log *) JFS_SBI(tblk->sb)->log;
450         logdiff(difft, lsn, log);
451 
452         /*
453          * update the block state a dmap at a time.
454          */
455         mp = NULL;
456         lastlblkno = 0;
457         for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
458                 /* get the buffer for the current dmap. */
459                 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
460                 if (lblkno != lastlblkno) {
461                         if (mp) {
462                                 write_metapage(mp);
463                         }
464 
465                         mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE,
466                                            0);
467                         if (mp == NULL)
468                                 return -EIO;
469                         metapage_wait_for_io(mp);
470                 }
471                 dp = (struct dmap *) mp->data;
472 
473                 /* determine the bit number and word within the dmap of
474                  * the starting block.  also determine how many blocks
475                  * are to be updated within this dmap.
476                  */
477                 dbitno = blkno & (BPERDMAP - 1);
478                 word = dbitno >> L2DBWORD;
479                 nblks = min(rem, (s64)BPERDMAP - dbitno);
480 
481                 /* update the bits of the dmap words. the first and last
482                  * words may only have a subset of their bits updated. if
483                  * this is the case, we'll work against that word (i.e.
484                  * partial first and/or last) only in a single pass.  a
485                  * single pass will also be used to update all words that
486                  * are to have all their bits updated.
487                  */
488                 for (rbits = nblks; rbits > 0;
489                      rbits -= nbits, dbitno += nbits) {
490                         /* determine the bit number within the word and
491                          * the number of bits within the word.
492                          */
493                         wbitno = dbitno & (DBWORD - 1);
494                         nbits = min(rbits, DBWORD - wbitno);
495 
496                         /* check if only part of the word is to be updated. */
497                         if (nbits < DBWORD) {
498                                 /* update (free or allocate) the bits
499                                  * in this word.
500                                  */
501                                 mask =
502                                     (ONES << (DBWORD - nbits) >> wbitno);
503                                 if (free)
504                                         dp->pmap[word] &=
505                                             cpu_to_le32(~mask);
506                                 else
507                                         dp->pmap[word] |=
508                                             cpu_to_le32(mask);
509 
510                                 word += 1;
511                         } else {
512                                 /* one or more words are to have all
513                                  * their bits updated.  determine how
514                                  * many words and how many bits.
515                                  */
516                                 nwords = rbits >> L2DBWORD;
517                                 nbits = nwords << L2DBWORD;
518 
519                                 /* update (free or allocate) the bits
520                                  * in these words.
521                                  */
522                                 if (free)
523                                         memset(&dp->pmap[word], 0,
524                                                nwords * 4);
525                                 else
526                                         memset(&dp->pmap[word], (int) ONES,
527                                                nwords * 4);
528 
529                                 word += nwords;
530                         }
531                 }
532 
533                 /*
534                  * update dmap lsn
535                  */
536                 if (lblkno == lastlblkno)
537                         continue;
538 
539                 lastlblkno = lblkno;
540 
541                 LOGSYNC_LOCK(log, flags);
542                 if (mp->lsn != 0) {
543                         /* inherit older/smaller lsn */
544                         logdiff(diffp, mp->lsn, log);
545                         if (difft < diffp) {
546                                 mp->lsn = lsn;
547 
548                                 /* move bp after tblock in logsync list */
549                                 list_move(&mp->synclist, &tblk->synclist);
550                         }
551 
552                         /* inherit younger/larger clsn */
553                         logdiff(difft, tblk->clsn, log);
554                         logdiff(diffp, mp->clsn, log);
555                         if (difft > diffp)
556                                 mp->clsn = tblk->clsn;
557                 } else {
558                         mp->log = log;
559                         mp->lsn = lsn;
560 
561                         /* insert bp after tblock in logsync list */
562                         log->count++;
563                         list_add(&mp->synclist, &tblk->synclist);
564 
565                         mp->clsn = tblk->clsn;
566                 }
567                 LOGSYNC_UNLOCK(log, flags);
568         }
569 
570         /* write the last buffer. */
571         if (mp) {
572                 write_metapage(mp);
573         }
574 
575         return (0);
576 }
577 
578 
579 /*
580  * NAME:        dbNextAG()
581  *
582  * FUNCTION:    find the preferred allocation group for new allocations.
583  *
584  *              Within the allocation groups, we maintain a preferred
585  *              allocation group which consists of a group with at least
586  *              average free space.  It is the preferred group that we target
587  *              new inode allocation towards.  The tie-in between inode
588  *              allocation and block allocation occurs as we allocate the
589  *              first (data) block of an inode and specify the inode (block)
590  *              as the allocation hint for this block.
591  *
592  *              We try to avoid having more than one open file growing in
593  *              an allocation group, as this will lead to fragmentation.
594  *              This differs from the old OS/2 method of trying to keep
595  *              empty ags around for large allocations.
596  *
597  * PARAMETERS:
598  *      ipbmap  - pointer to in-core inode for the block map.
599  *
600  * RETURN VALUES:
601  *      the preferred allocation group number.
602  */
603 int dbNextAG(struct inode *ipbmap)
604 {
605         s64 avgfree;
606         int agpref;
607         s64 hwm = 0;
608         int i;
609         int next_best = -1;
610         struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
611 
612         BMAP_LOCK(bmp);
613 
614         /* determine the average number of free blocks within the ags. */
615         avgfree = (u32)bmp->db_nfree / bmp->db_numag;
616 
617         /*
618          * if the current preferred ag does not have an active allocator
619          * and has at least average freespace, return it
620          */
621         agpref = bmp->db_agpref;
622         if ((atomic_read(&bmp->db_active[agpref]) == 0) &&
623             (bmp->db_agfree[agpref] >= avgfree))
624                 goto unlock;
625 
626         /* From the last preferred ag, find the next one with at least
627          * average free space.
628          */
629         for (i = 0 ; i < bmp->db_numag; i++, agpref++) {
630                 if (agpref == bmp->db_numag)
631                         agpref = 0;
632 
633                 if (atomic_read(&bmp->db_active[agpref]))
634                         /* open file is currently growing in this ag */
635                         continue;
636                 if (bmp->db_agfree[agpref] >= avgfree) {
637                         /* Return this one */
638                         bmp->db_agpref = agpref;
639                         goto unlock;
640                 } else if (bmp->db_agfree[agpref] > hwm) {
641                         /* Less than avg. freespace, but best so far */
642                         hwm = bmp->db_agfree[agpref];
643                         next_best = agpref;
644                 }
645         }
646 
647         /*
648          * If no inactive ag was found with average freespace, use the
649          * next best
650          */
651         if (next_best != -1)
652                 bmp->db_agpref = next_best;
653         /* else leave db_agpref unchanged */
654 unlock:
655         BMAP_UNLOCK(bmp);
656 
657         /* return the preferred group.
658          */
659         return (bmp->db_agpref);
660 }
661 
662 /*
663  * NAME:        dbAlloc()
664  *
665  * FUNCTION:    attempt to allocate a specified number of contiguous free
666  *              blocks from the working allocation block map.
667  *
668  *              the block allocation policy uses hints and a multi-step
669  *              approach.
670  *
671  *              for allocation requests smaller than the number of blocks
672  *              per dmap, we first try to allocate the new blocks
673  *              immediately following the hint.  if these blocks are not
674  *              available, we try to allocate blocks near the hint.  if
675  *              no blocks near the hint are available, we next try to
676  *              allocate within the same dmap as contains the hint.
677  *
678  *              if no blocks are available in the dmap or the allocation
679  *              request is larger than the dmap size, we try to allocate
680  *              within the same allocation group as contains the hint. if
681  *              this does not succeed, we finally try to allocate anywhere
682  *              within the aggregate.
683  *
684  *              we also try to allocate anywhere within the aggregate for
685  *              for allocation requests larger than the allocation group
686  *              size or requests that specify no hint value.
687  *
688  * PARAMETERS:
689  *      ip      - pointer to in-core inode;
690  *      hint    - allocation hint.
691  *      nblocks - number of contiguous blocks in the range.
692  *      results - on successful return, set to the starting block number
693  *                of the newly allocated contiguous range.
694  *
695  * RETURN VALUES:
696  *      0       - success
697  *      -ENOSPC - insufficient disk resources
698  *      -EIO    - i/o error
699  */
700 int dbAlloc(struct inode *ip, s64 hint, s64 nblocks, s64 * results)
701 {
702         int rc, agno;
703         struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
704         struct bmap *bmp;
705         struct metapage *mp;
706         s64 lblkno, blkno;
707         struct dmap *dp;
708         int l2nb;
709         s64 mapSize;
710         int writers;
711 
712         /* assert that nblocks is valid */
713         assert(nblocks > 0);
714 
715         /* get the log2 number of blocks to be allocated.
716          * if the number of blocks is not a log2 multiple,
717          * it will be rounded up to the next log2 multiple.
718          */
719         l2nb = BLKSTOL2(nblocks);
720 
721         bmp = JFS_SBI(ip->i_sb)->bmap;
722 
723         mapSize = bmp->db_mapsize;
724 
725         /* the hint should be within the map */
726         if (hint >= mapSize) {
727                 jfs_error(ip->i_sb, "the hint is outside the map\n");
728                 return -EIO;
729         }
730 
731         /* if the number of blocks to be allocated is greater than the
732          * allocation group size, try to allocate anywhere.
733          */
734         if (l2nb > bmp->db_agl2size) {
735                 IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
736 
737                 rc = dbAllocAny(bmp, nblocks, l2nb, results);
738 
739                 goto write_unlock;
740         }
741 
742         /*
743          * If no hint, let dbNextAG recommend an allocation group
744          */
745         if (hint == 0)
746                 goto pref_ag;
747 
748         /* we would like to allocate close to the hint.  adjust the
749          * hint to the block following the hint since the allocators
750          * will start looking for free space starting at this point.
751          */
752         blkno = hint + 1;
753 
754         if (blkno >= bmp->db_mapsize)
755                 goto pref_ag;
756 
757         agno = blkno >> bmp->db_agl2size;
758 
759         /* check if blkno crosses over into a new allocation group.
760          * if so, check if we should allow allocations within this
761          * allocation group.
762          */
763         if ((blkno & (bmp->db_agsize - 1)) == 0)
764                 /* check if the AG is currently being written to.
765                  * if so, call dbNextAG() to find a non-busy
766                  * AG with sufficient free space.
767                  */
768                 if (atomic_read(&bmp->db_active[agno]))
769                         goto pref_ag;
770 
771         /* check if the allocation request size can be satisfied from a
772          * single dmap.  if so, try to allocate from the dmap containing
773          * the hint using a tiered strategy.
774          */
775         if (nblocks <= BPERDMAP) {
776                 IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
777 
778                 /* get the buffer for the dmap containing the hint.
779                  */
780                 rc = -EIO;
781                 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
782                 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
783                 if (mp == NULL)
784                         goto read_unlock;
785 
786                 dp = (struct dmap *) mp->data;
787 
788                 /* first, try to satisfy the allocation request with the
789                  * blocks beginning at the hint.
790                  */
791                 if ((rc = dbAllocNext(bmp, dp, blkno, (int) nblocks))
792                     != -ENOSPC) {
793                         if (rc == 0) {
794                                 *results = blkno;
795                                 mark_metapage_dirty(mp);
796                         }
797 
798                         release_metapage(mp);
799                         goto read_unlock;
800                 }
801 
802                 writers = atomic_read(&bmp->db_active[agno]);
803                 if ((writers > 1) ||
804                     ((writers == 1) && (JFS_IP(ip)->active_ag != agno))) {
805                         /*
806                          * Someone else is writing in this allocation
807                          * group.  To avoid fragmenting, try another ag
808                          */
809                         release_metapage(mp);
810                         IREAD_UNLOCK(ipbmap);
811                         goto pref_ag;
812                 }
813 
814                 /* next, try to satisfy the allocation request with blocks
815                  * near the hint.
816                  */
817                 if ((rc =
818                      dbAllocNear(bmp, dp, blkno, (int) nblocks, l2nb, results))
819                     != -ENOSPC) {
820                         if (rc == 0)
821                                 mark_metapage_dirty(mp);
822 
823                         release_metapage(mp);
824                         goto read_unlock;
825                 }
826 
827                 /* try to satisfy the allocation request with blocks within
828                  * the same dmap as the hint.
829                  */
830                 if ((rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results))
831                     != -ENOSPC) {
832                         if (rc == 0)
833                                 mark_metapage_dirty(mp);
834 
835                         release_metapage(mp);
836                         goto read_unlock;
837                 }
838 
839                 release_metapage(mp);
840                 IREAD_UNLOCK(ipbmap);
841         }
842 
843         /* try to satisfy the allocation request with blocks within
844          * the same allocation group as the hint.
845          */
846         IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
847         if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) != -ENOSPC)
848                 goto write_unlock;
849 
850         IWRITE_UNLOCK(ipbmap);
851 
852 
853       pref_ag:
854         /*
855          * Let dbNextAG recommend a preferred allocation group
856          */
857         agno = dbNextAG(ipbmap);
858         IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
859 
860         /* Try to allocate within this allocation group.  if that fails, try to
861          * allocate anywhere in the map.
862          */
863         if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) == -ENOSPC)
864                 rc = dbAllocAny(bmp, nblocks, l2nb, results);
865 
866       write_unlock:
867         IWRITE_UNLOCK(ipbmap);
868 
869         return (rc);
870 
871       read_unlock:
872         IREAD_UNLOCK(ipbmap);
873 
874         return (rc);
875 }
876 
877 #ifdef _NOTYET
878 /*
879  * NAME:        dbAllocExact()
880  *
881  * FUNCTION:    try to allocate the requested extent;
882  *
883  * PARAMETERS:
884  *      ip      - pointer to in-core inode;
885  *      blkno   - extent address;
886  *      nblocks - extent length;
887  *
888  * RETURN VALUES:
889  *      0       - success
890  *      -ENOSPC - insufficient disk resources
891  *      -EIO    - i/o error
892  */
893 int dbAllocExact(struct inode *ip, s64 blkno, int nblocks)
894 {
895         int rc;
896         struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
897         struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
898         struct dmap *dp;
899         s64 lblkno;
900         struct metapage *mp;
901 
902         IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
903 
904         /*
905          * validate extent request:
906          *
907          * note: defragfs policy:
908          *  max 64 blocks will be moved.
909          *  allocation request size must be satisfied from a single dmap.
910          */
911         if (nblocks <= 0 || nblocks > BPERDMAP || blkno >= bmp->db_mapsize) {
912                 IREAD_UNLOCK(ipbmap);
913                 return -EINVAL;
914         }
915 
916         if (nblocks > ((s64) 1 << bmp->db_maxfreebud)) {
917                 /* the free space is no longer available */
918                 IREAD_UNLOCK(ipbmap);
919                 return -ENOSPC;
920         }
921 
922         /* read in the dmap covering the extent */
923         lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
924         mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
925         if (mp == NULL) {
926                 IREAD_UNLOCK(ipbmap);
927                 return -EIO;
928         }
929         dp = (struct dmap *) mp->data;
930 
931         /* try to allocate the requested extent */
932         rc = dbAllocNext(bmp, dp, blkno, nblocks);
933 
934         IREAD_UNLOCK(ipbmap);
935 
936         if (rc == 0)
937                 mark_metapage_dirty(mp);
938 
939         release_metapage(mp);
940 
941         return (rc);
942 }
943 #endif /* _NOTYET */
944 
945 /*
946  * NAME:        dbReAlloc()
947  *
948  * FUNCTION:    attempt to extend a current allocation by a specified
949  *              number of blocks.
950  *
951  *              this routine attempts to satisfy the allocation request
952  *              by first trying to extend the existing allocation in
953  *              place by allocating the additional blocks as the blocks
954  *              immediately following the current allocation.  if these
955  *              blocks are not available, this routine will attempt to
956  *              allocate a new set of contiguous blocks large enough
957  *              to cover the existing allocation plus the additional
958  *              number of blocks required.
959  *
960  * PARAMETERS:
961  *      ip          -  pointer to in-core inode requiring allocation.
962  *      blkno       -  starting block of the current allocation.
963  *      nblocks     -  number of contiguous blocks within the current
964  *                     allocation.
965  *      addnblocks  -  number of blocks to add to the allocation.
966  *      results -      on successful return, set to the starting block number
967  *                     of the existing allocation if the existing allocation
968  *                     was extended in place or to a newly allocated contiguous
969  *                     range if the existing allocation could not be extended
970  *                     in place.
971  *
972  * RETURN VALUES:
973  *      0       - success
974  *      -ENOSPC - insufficient disk resources
975  *      -EIO    - i/o error
976  */
977 int
978 dbReAlloc(struct inode *ip,
979           s64 blkno, s64 nblocks, s64 addnblocks, s64 * results)
980 {
981         int rc;
982 
983         /* try to extend the allocation in place.
984          */
985         if ((rc = dbExtend(ip, blkno, nblocks, addnblocks)) == 0) {
986                 *results = blkno;
987                 return (0);
988         } else {
989                 if (rc != -ENOSPC)
990                         return (rc);
991         }
992 
993         /* could not extend the allocation in place, so allocate a
994          * new set of blocks for the entire request (i.e. try to get
995          * a range of contiguous blocks large enough to cover the
996          * existing allocation plus the additional blocks.)
997          */
998         return (dbAlloc
999                 (ip, blkno + nblocks - 1, addnblocks + nblocks, results));
1000 }
1001 
1002 
1003 /*
1004  * NAME:        dbExtend()
1005  *
1006  * FUNCTION:    attempt to extend a current allocation by a specified
1007  *              number of blocks.
1008  *
1009  *              this routine attempts to satisfy the allocation request
1010  *              by first trying to extend the existing allocation in
1011  *              place by allocating the additional blocks as the blocks
1012  *              immediately following the current allocation.
1013  *
1014  * PARAMETERS:
1015  *      ip          -  pointer to in-core inode requiring allocation.
1016  *      blkno       -  starting block of the current allocation.
1017  *      nblocks     -  number of contiguous blocks within the current
1018  *                     allocation.
1019  *      addnblocks  -  number of blocks to add to the allocation.
1020  *
1021  * RETURN VALUES:
1022  *      0       - success
1023  *      -ENOSPC - insufficient disk resources
1024  *      -EIO    - i/o error
1025  */
1026 static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks)
1027 {
1028         struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
1029         s64 lblkno, lastblkno, extblkno;
1030         uint rel_block;
1031         struct metapage *mp;
1032         struct dmap *dp;
1033         int rc;
1034         struct inode *ipbmap = sbi->ipbmap;
1035         struct bmap *bmp;
1036 
1037         /*
1038          * We don't want a non-aligned extent to cross a page boundary
1039          */
1040         if (((rel_block = blkno & (sbi->nbperpage - 1))) &&
1041             (rel_block + nblocks + addnblocks > sbi->nbperpage))
1042                 return -ENOSPC;
1043 
1044         /* get the last block of the current allocation */
1045         lastblkno = blkno + nblocks - 1;
1046 
1047         /* determine the block number of the block following
1048          * the existing allocation.
1049          */
1050         extblkno = lastblkno + 1;
1051 
1052         IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
1053 
1054         /* better be within the file system */
1055         bmp = sbi->bmap;
1056         if (lastblkno < 0 || lastblkno >= bmp->db_mapsize) {
1057                 IREAD_UNLOCK(ipbmap);
1058                 jfs_error(ip->i_sb, "the block is outside the filesystem\n");
1059                 return -EIO;
1060         }
1061 
1062         /* we'll attempt to extend the current allocation in place by
1063          * allocating the additional blocks as the blocks immediately
1064          * following the current allocation.  we only try to extend the
1065          * current allocation in place if the number of additional blocks
1066          * can fit into a dmap, the last block of the current allocation
1067          * is not the last block of the file system, and the start of the
1068          * inplace extension is not on an allocation group boundary.
1069          */
1070         if (addnblocks > BPERDMAP || extblkno >= bmp->db_mapsize ||
1071             (extblkno & (bmp->db_agsize - 1)) == 0) {
1072                 IREAD_UNLOCK(ipbmap);
1073                 return -ENOSPC;
1074         }
1075 
1076         /* get the buffer for the dmap containing the first block
1077          * of the extension.
1078          */
1079         lblkno = BLKTODMAP(extblkno, bmp->db_l2nbperpage);
1080         mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
1081         if (mp == NULL) {
1082                 IREAD_UNLOCK(ipbmap);
1083                 return -EIO;
1084         }
1085 
1086         dp = (struct dmap *) mp->data;
1087 
1088         /* try to allocate the blocks immediately following the
1089          * current allocation.
1090          */
1091         rc = dbAllocNext(bmp, dp, extblkno, (int) addnblocks);
1092 
1093         IREAD_UNLOCK(ipbmap);
1094 
1095         /* were we successful ? */
1096         if (rc == 0)
1097                 write_metapage(mp);
1098         else
1099                 /* we were not successful */
1100                 release_metapage(mp);
1101 
1102         return (rc);
1103 }
1104 
1105 
1106 /*
1107  * NAME:        dbAllocNext()
1108  *
1109  * FUNCTION:    attempt to allocate the blocks of the specified block
1110  *              range within a dmap.
1111  *
1112  * PARAMETERS:
1113  *      bmp     -  pointer to bmap descriptor
1114  *      dp      -  pointer to dmap.
1115  *      blkno   -  starting block number of the range.
1116  *      nblocks -  number of contiguous free blocks of the range.
1117  *
1118  * RETURN VALUES:
1119  *      0       - success
1120  *      -ENOSPC - insufficient disk resources
1121  *      -EIO    - i/o error
1122  *
1123  * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1124  */
1125 static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
1126                        int nblocks)
1127 {
1128         int dbitno, word, rembits, nb, nwords, wbitno, nw;
1129         int l2size;
1130         s8 *leaf;
1131         u32 mask;
1132 
1133         if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1134                 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmap page\n");
1135                 return -EIO;
1136         }
1137 
1138         /* pick up a pointer to the leaves of the dmap tree.
1139          */
1140         leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1141 
1142         /* determine the bit number and word within the dmap of the
1143          * starting block.
1144          */
1145         dbitno = blkno & (BPERDMAP - 1);
1146         word = dbitno >> L2DBWORD;
1147 
1148         /* check if the specified block range is contained within
1149          * this dmap.
1150          */
1151         if (dbitno + nblocks > BPERDMAP)
1152                 return -ENOSPC;
1153 
1154         /* check if the starting leaf indicates that anything
1155          * is free.
1156          */
1157         if (leaf[word] == NOFREE)
1158                 return -ENOSPC;
1159 
1160         /* check the dmaps words corresponding to block range to see
1161          * if the block range is free.  not all bits of the first and
1162          * last words may be contained within the block range.  if this
1163          * is the case, we'll work against those words (i.e. partial first
1164          * and/or last) on an individual basis (a single pass) and examine
1165          * the actual bits to determine if they are free.  a single pass
1166          * will be used for all dmap words fully contained within the
1167          * specified range.  within this pass, the leaves of the dmap
1168          * tree will be examined to determine if the blocks are free. a
1169          * single leaf may describe the free space of multiple dmap
1170          * words, so we may visit only a subset of the actual leaves
1171          * corresponding to the dmap words of the block range.
1172          */
1173         for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
1174                 /* determine the bit number within the word and
1175                  * the number of bits within the word.
1176                  */
1177                 wbitno = dbitno & (DBWORD - 1);
1178                 nb = min(rembits, DBWORD - wbitno);
1179 
1180                 /* check if only part of the word is to be examined.
1181                  */
1182                 if (nb < DBWORD) {
1183                         /* check if the bits are free.
1184                          */
1185                         mask = (ONES << (DBWORD - nb) >> wbitno);
1186                         if ((mask & ~le32_to_cpu(dp->wmap[word])) != mask)
1187                                 return -ENOSPC;
1188 
1189                         word += 1;
1190                 } else {
1191                         /* one or more dmap words are fully contained
1192                          * within the block range.  determine how many
1193                          * words and how many bits.
1194                          */
1195                         nwords = rembits >> L2DBWORD;
1196                         nb = nwords << L2DBWORD;
1197 
1198                         /* now examine the appropriate leaves to determine
1199                          * if the blocks are free.
1200                          */
1201                         while (nwords > 0) {
1202                                 /* does the leaf describe any free space ?
1203                                  */
1204                                 if (leaf[word] < BUDMIN)
1205                                         return -ENOSPC;
1206 
1207                                 /* determine the l2 number of bits provided
1208                                  * by this leaf.
1209                                  */
1210                                 l2size =
1211                                     min_t(int, leaf[word], NLSTOL2BSZ(nwords));
1212 
1213                                 /* determine how many words were handled.
1214                                  */
1215                                 nw = BUDSIZE(l2size, BUDMIN);
1216 
1217                                 nwords -= nw;
1218                                 word += nw;
1219                         }
1220                 }
1221         }
1222 
1223         /* allocate the blocks.
1224          */
1225         return (dbAllocDmap(bmp, dp, blkno, nblocks));
1226 }
1227 
1228 
1229 /*
1230  * NAME:        dbAllocNear()
1231  *
1232  * FUNCTION:    attempt to allocate a number of contiguous free blocks near
1233  *              a specified block (hint) within a dmap.
1234  *
1235  *              starting with the dmap leaf that covers the hint, we'll
1236  *              check the next four contiguous leaves for sufficient free
1237  *              space.  if sufficient free space is found, we'll allocate
1238  *              the desired free space.
1239  *
1240  * PARAMETERS:
1241  *      bmp     -  pointer to bmap descriptor
1242  *      dp      -  pointer to dmap.
1243  *      blkno   -  block number to allocate near.
1244  *      nblocks -  actual number of contiguous free blocks desired.
1245  *      l2nb    -  log2 number of contiguous free blocks desired.
1246  *      results -  on successful return, set to the starting block number
1247  *                 of the newly allocated range.
1248  *
1249  * RETURN VALUES:
1250  *      0       - success
1251  *      -ENOSPC - insufficient disk resources
1252  *      -EIO    - i/o error
1253  *
1254  * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1255  */
1256 static int
1257 dbAllocNear(struct bmap * bmp,
1258             struct dmap * dp, s64 blkno, int nblocks, int l2nb, s64 * results)
1259 {
1260         int word, lword, rc;
1261         s8 *leaf;
1262 
1263         if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1264                 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmap page\n");
1265                 return -EIO;
1266         }
1267 
1268         leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1269 
1270         /* determine the word within the dmap that holds the hint
1271          * (i.e. blkno).  also, determine the last word in the dmap
1272          * that we'll include in our examination.
1273          */
1274         word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
1275         lword = min(word + 4, LPERDMAP);
1276 
1277         /* examine the leaves for sufficient free space.
1278          */
1279         for (; word < lword; word++) {
1280                 /* does the leaf describe sufficient free space ?
1281                  */
1282                 if (leaf[word] < l2nb)
1283                         continue;
1284 
1285                 /* determine the block number within the file system
1286                  * of the first block described by this dmap word.
1287                  */
1288                 blkno = le64_to_cpu(dp->start) + (word << L2DBWORD);
1289 
1290                 /* if not all bits of the dmap word are free, get the
1291                  * starting bit number within the dmap word of the required
1292                  * string of free bits and adjust the block number with the
1293                  * value.
1294                  */
1295                 if (leaf[word] < BUDMIN)
1296                         blkno +=
1297                             dbFindBits(le32_to_cpu(dp->wmap[word]), l2nb);
1298 
1299                 /* allocate the blocks.
1300                  */
1301                 if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1302                         *results = blkno;
1303 
1304                 return (rc);
1305         }
1306 
1307         return -ENOSPC;
1308 }
1309 
1310 
1311 /*
1312  * NAME:        dbAllocAG()
1313  *
1314  * FUNCTION:    attempt to allocate the specified number of contiguous
1315  *              free blocks within the specified allocation group.
1316  *
1317  *              unless the allocation group size is equal to the number
1318  *              of blocks per dmap, the dmap control pages will be used to
1319  *              find the required free space, if available.  we start the
1320  *              search at the highest dmap control page level which
1321  *              distinctly describes the allocation group's free space
1322  *              (i.e. the highest level at which the allocation group's
1323  *              free space is not mixed in with that of any other group).
1324  *              in addition, we start the search within this level at a
1325  *              height of the dmapctl dmtree at which the nodes distinctly
1326  *              describe the allocation group's free space.  at this height,
1327  *              the allocation group's free space may be represented by 1
1328  *              or two sub-trees, depending on the allocation group size.
1329  *              we search the top nodes of these subtrees left to right for
1330  *              sufficient free space.  if sufficient free space is found,
1331  *              the subtree is searched to find the leftmost leaf that
1332  *              has free space.  once we have made it to the leaf, we
1333  *              move the search to the next lower level dmap control page
1334  *              corresponding to this leaf.  we continue down the dmap control
1335  *              pages until we find the dmap that contains or starts the
1336  *              sufficient free space and we allocate at this dmap.
1337  *
1338  *              if the allocation group size is equal to the dmap size,
1339  *              we'll start at the dmap corresponding to the allocation
1340  *              group and attempt the allocation at this level.
1341  *
1342  *              the dmap control page search is also not performed if the
1343  *              allocation group is completely free and we go to the first
1344  *              dmap of the allocation group to do the allocation.  this is
1345  *              done because the allocation group may be part (not the first
1346  *              part) of a larger binary buddy system, causing the dmap
1347  *              control pages to indicate no free space (NOFREE) within
1348  *              the allocation group.
1349  *
1350  * PARAMETERS:
1351  *      bmp     -  pointer to bmap descriptor
1352  *      agno    - allocation group number.
1353  *      nblocks -  actual number of contiguous free blocks desired.
1354  *      l2nb    -  log2 number of contiguous free blocks desired.
1355  *      results -  on successful return, set to the starting block number
1356  *                 of the newly allocated range.
1357  *
1358  * RETURN VALUES:
1359  *      0       - success
1360  *      -ENOSPC - insufficient disk resources
1361  *      -EIO    - i/o error
1362  *
1363  * note: IWRITE_LOCK(ipmap) held on entry/exit;
1364  */
1365 static int
1366 dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
1367 {
1368         struct metapage *mp;
1369         struct dmapctl *dcp;
1370         int rc, ti, i, k, m, n, agperlev;
1371         s64 blkno, lblkno;
1372         int budmin;
1373 
1374         /* allocation request should not be for more than the
1375          * allocation group size.
1376          */
1377         if (l2nb > bmp->db_agl2size) {
1378                 jfs_error(bmp->db_ipbmap->i_sb,
1379                           "allocation request is larger than the allocation group size\n");
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                                   "dbAllocCtl failed in free AG\n");
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, "Corrupt dmapctl page\n");
1431                 release_metapage(mp);
1432                 return -EIO;
1433         }
1434 
1435         /* search the subtree(s) of the dmap control page that describes
1436          * the allocation group, looking for sufficient free space.  to begin,
1437          * determine how many allocation groups are represented in a dmap
1438          * control page at the control page level (i.e. L0, L1, L2) that
1439          * fully describes an allocation group. next, determine the starting
1440          * tree index of this allocation group within the control page.
1441          */
1442         agperlev =
1443             (1 << (L2LPERCTL - (bmp->db_agheight << 1))) / bmp->db_agwidth;
1444         ti = bmp->db_agstart + bmp->db_agwidth * (agno & (agperlev - 1));
1445 
1446         /* dmap control page trees fan-out by 4 and a single allocation
1447          * group may be described by 1 or 2 subtrees within the ag level
1448          * dmap control page, depending upon the ag size. examine the ag's
1449          * subtrees for sufficient free space, starting with the leftmost
1450          * subtree.
1451          */
1452         for (i = 0; i < bmp->db_agwidth; i++, ti++) {
1453                 /* is there sufficient free space ?
1454                  */
1455                 if (l2nb > dcp->stree[ti])
1456                         continue;
1457 
1458                 /* sufficient free space found in a subtree. now search down
1459                  * the subtree to find the leftmost leaf that describes this
1460                  * free space.
1461                  */
1462                 for (k = bmp->db_agheight; k > 0; k--) {
1463                         for (n = 0, m = (ti << 2) + 1; n < 4; n++) {
1464                                 if (l2nb <= dcp->stree[m + n]) {
1465                                         ti = m + n;
1466                                         break;
1467                                 }
1468                         }
1469                         if (n == 4) {
1470                                 jfs_error(bmp->db_ipbmap->i_sb,
1471                                           "failed descending stree\n");
1472                                 release_metapage(mp);
1473                                 return -EIO;
1474                         }
1475                 }
1476 
1477                 /* determine the block number within the file system
1478                  * that corresponds to this leaf.
1479                  */
1480                 if (bmp->db_aglevel == 2)
1481                         blkno = 0;
1482                 else if (bmp->db_aglevel == 1)
1483                         blkno &= ~(MAXL1SIZE - 1);
1484                 else            /* bmp->db_aglevel == 0 */
1485                         blkno &= ~(MAXL0SIZE - 1);
1486 
1487                 blkno +=
1488                     ((s64) (ti - le32_to_cpu(dcp->leafidx))) << budmin;
1489 
1490                 /* release the buffer in preparation for going down
1491                  * the next level of dmap control pages.
1492                  */
1493                 release_metapage(mp);
1494 
1495                 /* check if we need to continue to search down the lower
1496                  * level dmap control pages.  we need to if the number of
1497                  * blocks required is less than maximum number of blocks
1498                  * described at the next lower level.
1499                  */
1500                 if (l2nb < budmin) {
1501 
1502                         /* search the lower level dmap control pages to get
1503                          * the starting block number of the dmap that
1504                          * contains or starts off the free space.
1505                          */
1506                         if ((rc =
1507                              dbFindCtl(bmp, l2nb, bmp->db_aglevel - 1,
1508                                        &blkno))) {
1509                                 if (rc == -ENOSPC) {
1510                                         jfs_error(bmp->db_ipbmap->i_sb,
1511                                                   "control page inconsistent\n");
1512                                         return -EIO;
1513                                 }
1514                                 return (rc);
1515                         }
1516                 }
1517 
1518                 /* allocate the blocks.
1519                  */
1520                 rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1521                 if (rc == -ENOSPC) {
1522                         jfs_error(bmp->db_ipbmap->i_sb,
1523                                   "unable to allocate blocks\n");
1524                         rc = -EIO;
1525                 }
1526                 return (rc);
1527         }
1528 
1529         /* no space in the allocation group.  release the buffer and
1530          * return -ENOSPC.
1531          */
1532         release_metapage(mp);
1533 
1534         return -ENOSPC;
1535 }
1536 
1537 
1538 /*
1539  * NAME:        dbAllocAny()
1540  *
1541  * FUNCTION:    attempt to allocate the specified number of contiguous
1542  *              free blocks anywhere in the file system.
1543  *
1544  *              dbAllocAny() attempts to find the sufficient free space by
1545  *              searching down the dmap control pages, starting with the
1546  *              highest level (i.e. L0, L1, L2) control page.  if free space
1547  *              large enough to satisfy the desired free space is found, the
1548  *              desired free space is allocated.
1549  *
1550  * PARAMETERS:
1551  *      bmp     -  pointer to bmap descriptor
1552  *      nblocks  -  actual number of contiguous free blocks desired.
1553  *      l2nb     -  log2 number of contiguous free blocks desired.
1554  *      results -  on successful return, set to the starting block number
1555  *                 of the newly allocated range.
1556  *
1557  * RETURN VALUES:
1558  *      0       - success
1559  *      -ENOSPC - insufficient disk resources
1560  *      -EIO    - i/o error
1561  *
1562  * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1563  */
1564 static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results)
1565 {
1566         int rc;
1567         s64 blkno = 0;
1568 
1569         /* starting with the top level dmap control page, search
1570          * down the dmap control levels for sufficient free space.
1571          * if free space is found, dbFindCtl() returns the starting
1572          * block number of the dmap that contains or starts off the
1573          * range of free space.
1574          */
1575         if ((rc = dbFindCtl(bmp, l2nb, bmp->db_maxlevel, &blkno)))
1576                 return (rc);
1577 
1578         /* allocate the blocks.
1579          */
1580         rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1581         if (rc == -ENOSPC) {
1582                 jfs_error(bmp->db_ipbmap->i_sb, "unable to allocate blocks\n");
1583                 return -EIO;
1584         }
1585         return (rc);
1586 }
1587 
1588 
1589 /*
1590  * NAME:        dbDiscardAG()
1591  *
1592  * FUNCTION:    attempt to discard (TRIM) all free blocks of specific AG
1593  *
1594  *              algorithm:
1595  *              1) allocate blocks, as large as possible and save them
1596  *                 while holding IWRITE_LOCK on ipbmap
1597  *              2) trim all these saved block/length values
1598  *              3) mark the blocks free again
1599  *
1600  *              benefit:
1601  *              - we work only on one ag at some time, minimizing how long we
1602  *                need to lock ipbmap
1603  *              - reading / writing the fs is possible most time, even on
1604  *                trimming
1605  *
1606  *              downside:
1607  *              - we write two times to the dmapctl and dmap pages
1608  *              - but for me, this seems the best way, better ideas?
1609  *              /TR 2012
1610  *
1611  * PARAMETERS:
1612  *      ip      - pointer to in-core inode
1613  *      agno    - ag to trim
1614  *      minlen  - minimum value of contiguous blocks
1615  *
1616  * RETURN VALUES:
1617  *      s64     - actual number of blocks trimmed
1618  */
1619 s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen)
1620 {
1621         struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
1622         struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
1623         s64 nblocks, blkno;
1624         u64 trimmed = 0;
1625         int rc, l2nb;
1626         struct super_block *sb = ipbmap->i_sb;
1627 
1628         struct range2trim {
1629                 u64 blkno;
1630                 u64 nblocks;
1631         } *totrim, *tt;
1632 
1633         /* max blkno / nblocks pairs to trim */
1634         int count = 0, range_cnt;
1635         u64 max_ranges;
1636 
1637         /* prevent others from writing new stuff here, while trimming */
1638         IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
1639 
1640         nblocks = bmp->db_agfree[agno];
1641         max_ranges = nblocks;
1642         do_div(max_ranges, minlen);
1643         range_cnt = min_t(u64, max_ranges + 1, 32 * 1024);
1644         totrim = kmalloc(sizeof(struct range2trim) * range_cnt, GFP_NOFS);
1645         if (totrim == NULL) {
1646                 jfs_error(bmp->db_ipbmap->i_sb, "no memory for trim array\n");
1647                 IWRITE_UNLOCK(ipbmap);
1648                 return 0;
1649         }
1650 
1651         tt = totrim;
1652         while (nblocks >= minlen) {
1653                 l2nb = BLKSTOL2(nblocks);
1654 
1655                 /* 0 = okay, -EIO = fatal, -ENOSPC -> try smaller block */
1656                 rc = dbAllocAG(bmp, agno, nblocks, l2nb, &blkno);
1657                 if (rc == 0) {
1658                         tt->blkno = blkno;
1659                         tt->nblocks = nblocks;
1660                         tt++; count++;
1661 
1662                         /* the whole ag is free, trim now */
1663                         if (bmp->db_agfree[agno] == 0)
1664                                 break;
1665 
1666                         /* give a hint for the next while */
1667                         nblocks = bmp->db_agfree[agno];
1668                         continue;
1669                 } else if (rc == -ENOSPC) {
1670                         /* search for next smaller log2 block */
1671                         l2nb = BLKSTOL2(nblocks) - 1;
1672                         nblocks = 1 << l2nb;
1673                 } else {
1674                         /* Trim any already allocated blocks */
1675                         jfs_error(bmp->db_ipbmap->i_sb, "-EIO\n");
1676                         break;
1677                 }
1678 
1679                 /* check, if our trim array is full */
1680                 if (unlikely(count >= range_cnt - 1))
1681                         break;
1682         }
1683         IWRITE_UNLOCK(ipbmap);
1684 
1685         tt->nblocks = 0; /* mark the current end */
1686         for (tt = totrim; tt->nblocks != 0; tt++) {
1687                 /* when mounted with online discard, dbFree() will
1688                  * call jfs_issue_discard() itself */
1689                 if (!(JFS_SBI(sb)->flag & JFS_DISCARD))
1690                         jfs_issue_discard(ip, tt->blkno, tt->nblocks);
1691                 dbFree(ip, tt->blkno, tt->nblocks);
1692                 trimmed += tt->nblocks;
1693         }
1694         kfree(totrim);
1695 
1696         return trimmed;
1697 }
1698 
1699 /*
1700  * NAME:        dbFindCtl()
1701  *
1702  * FUNCTION:    starting at a specified dmap control page level and block
1703  *              number, search down the dmap control levels for a range of
1704  *              contiguous free blocks large enough to satisfy an allocation
1705  *              request for the specified number of free blocks.
1706  *
1707  *              if sufficient contiguous free blocks are found, this routine
1708  *              returns the starting block number within a dmap page that
1709  *              contains or starts a range of contiqious free blocks that
1710  *              is sufficient in size.
1711  *
1712  * PARAMETERS:
1713  *      bmp     -  pointer to bmap descriptor
1714  *      level   -  starting dmap control page level.
1715  *      l2nb    -  log2 number of contiguous free blocks desired.
1716  *      *blkno  -  on entry, starting block number for conducting the search.
1717  *                 on successful return, the first block within a dmap page
1718  *                 that contains or starts a range of contiguous free blocks.
1719  *
1720  * RETURN VALUES:
1721  *      0       - success
1722  *      -ENOSPC - insufficient disk resources
1723  *      -EIO    - i/o error
1724  *
1725  * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1726  */
1727 static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno)
1728 {
1729         int rc, leafidx, lev;
1730         s64 b, lblkno;
1731         struct dmapctl *dcp;
1732         int budmin;
1733         struct metapage *mp;
1734 
1735         /* starting at the specified dmap control page level and block
1736          * number, search down the dmap control levels for the starting
1737          * block number of a dmap page that contains or starts off
1738          * sufficient free blocks.
1739          */
1740         for (lev = level, b = *blkno; lev >= 0; lev--) {
1741                 /* get the buffer of the dmap control page for the block
1742                  * number and level (i.e. L0, L1, L2).
1743                  */
1744                 lblkno = BLKTOCTL(b, bmp->db_l2nbperpage, lev);
1745                 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1746                 if (mp == NULL)
1747                         return -EIO;
1748                 dcp = (struct dmapctl *) mp->data;
1749                 budmin = dcp->budmin;
1750 
1751                 if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1752                         jfs_error(bmp->db_ipbmap->i_sb,
1753                                   "Corrupt dmapctl page\n");
1754                         release_metapage(mp);
1755                         return -EIO;
1756                 }
1757 
1758                 /* search the tree within the dmap control page for
1759                  * sufficient free space.  if sufficient free space is found,
1760                  * dbFindLeaf() returns the index of the leaf at which
1761                  * free space was found.
1762                  */
1763                 rc = dbFindLeaf((dmtree_t *) dcp, l2nb, &leafidx);
1764 
1765                 /* release the buffer.
1766                  */
1767                 release_metapage(mp);
1768 
1769                 /* space found ?
1770                  */
1771                 if (rc) {
1772                         if (lev != level) {
1773                                 jfs_error(bmp->db_ipbmap->i_sb,
1774                                           "dmap inconsistent\n");
1775                                 return -EIO;
1776                         }
1777                         return -ENOSPC;
1778                 }
1779 
1780                 /* adjust the block number to reflect the location within
1781                  * the dmap control page (i.e. the leaf) at which free
1782                  * space was found.
1783                  */
1784                 b += (((s64) leafidx) << budmin);
1785 
1786                 /* we stop the search at this dmap control page level if
1787                  * the number of blocks required is greater than or equal
1788                  * to the maximum number of blocks described at the next
1789                  * (lower) level.
1790                  */
1791                 if (l2nb >= budmin)
1792                         break;
1793         }
1794 
1795         *blkno = b;
1796         return (0);
1797 }
1798 
1799 
1800 /*
1801  * NAME:        dbAllocCtl()
1802  *
1803  * FUNCTION:    attempt to allocate a specified number of contiguous
1804  *              blocks starting within a specific dmap.
1805  *
1806  *              this routine is called by higher level routines that search
1807  *              the dmap control pages above the actual dmaps for contiguous
1808  *              free space.  the result of successful searches by these
1809  *              routines are the starting block numbers within dmaps, with
1810  *              the dmaps themselves containing the desired contiguous free
1811  *              space or starting a contiguous free space of desired size
1812  *              that is made up of the blocks of one or more dmaps. these
1813  *              calls should not fail due to insufficent resources.
1814  *
1815  *              this routine is called in some cases where it is not known
1816  *              whether it will fail due to insufficient resources.  more
1817  *              specifically, this occurs when allocating from an allocation
1818  *              group whose size is equal to the number of blocks per dmap.
1819  *              in this case, the dmap control pages are not examined prior
1820  *              to calling this routine (to save pathlength) and the call
1821  *              might fail.
1822  *
1823  *              for a request size that fits within a dmap, this routine relies
1824  *              upon the dmap's dmtree to find the requested contiguous free
1825  *              space.  for request sizes that are larger than a dmap, the
1826  *              requested free space will start at the first block of the
1827  *              first dmap (i.e. blkno).
1828  *
1829  * PARAMETERS:
1830  *      bmp     -  pointer to bmap descriptor
1831  *      nblocks  -  actual number of contiguous free blocks to allocate.
1832  *      l2nb     -  log2 number of contiguous free blocks to allocate.
1833  *      blkno    -  starting block number of the dmap to start the allocation
1834  *                  from.
1835  *      results -  on successful return, set to the starting block number
1836  *                 of the newly allocated range.
1837  *
1838  * RETURN VALUES:
1839  *      0       - success
1840  *      -ENOSPC - insufficient disk resources
1841  *      -EIO    - i/o error
1842  *
1843  * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1844  */
1845 static int
1846 dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno, s64 * results)
1847 {
1848         int rc, nb;
1849         s64 b, lblkno, n;
1850         struct metapage *mp;
1851         struct dmap *dp;
1852 
1853         /* check if the allocation request is confined to a single dmap.
1854          */
1855         if (l2nb <= L2BPERDMAP) {
1856                 /* get the buffer for the dmap.
1857                  */
1858                 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
1859                 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1860                 if (mp == NULL)
1861                         return -EIO;
1862                 dp = (struct dmap *) mp->data;
1863 
1864                 /* try to allocate the blocks.
1865                  */
1866                 rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results);
1867                 if (rc == 0)
1868                         mark_metapage_dirty(mp);
1869 
1870                 release_metapage(mp);
1871 
1872                 return (rc);
1873         }
1874 
1875         /* allocation request involving multiple dmaps. it must start on
1876          * a dmap boundary.
1877          */
1878         assert((blkno & (BPERDMAP - 1)) == 0);
1879 
1880         /* allocate the blocks dmap by dmap.
1881          */
1882         for (n = nblocks, b = blkno; n > 0; n -= nb, b += nb) {
1883                 /* get the buffer for the dmap.
1884                  */
1885                 lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1886                 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1887                 if (mp == NULL) {
1888                         rc = -EIO;
1889                         goto backout;
1890                 }
1891                 dp = (struct dmap *) mp->data;
1892 
1893                 /* the dmap better be all free.
1894                  */
1895                 if (dp->tree.stree[ROOT] != L2BPERDMAP) {
1896                         release_metapage(mp);
1897                         jfs_error(bmp->db_ipbmap->i_sb,
1898                                   "the dmap is not all free\n");
1899                         rc = -EIO;
1900                         goto backout;
1901                 }
1902 
1903                 /* determine how many blocks to allocate from this dmap.
1904                  */
1905                 nb = min_t(s64, n, BPERDMAP);
1906 
1907                 /* allocate the blocks from the dmap.
1908                  */
1909                 if ((rc = dbAllocDmap(bmp, dp, b, nb))) {
1910                         release_metapage(mp);
1911                         goto backout;
1912                 }
1913 
1914                 /* write the buffer.
1915                  */
1916                 write_metapage(mp);
1917         }
1918 
1919         /* set the results (starting block number) and return.
1920          */
1921         *results = blkno;
1922         return (0);
1923 
1924         /* something failed in handling an allocation request involving
1925          * multiple dmaps.  we'll try to clean up by backing out any
1926          * allocation that has already happened for this request.  if
1927          * we fail in backing out the allocation, we'll mark the file
1928          * system to indicate that blocks have been leaked.
1929          */
1930       backout:
1931 
1932         /* try to backout the allocations dmap by dmap.
1933          */
1934         for (n = nblocks - n, b = blkno; n > 0;
1935              n -= BPERDMAP, b += BPERDMAP) {
1936                 /* get the buffer for this dmap.
1937                  */
1938                 lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1939                 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1940                 if (mp == NULL) {
1941                         /* could not back out.  mark the file system
1942                          * to indicate that we have leaked blocks.
1943                          */
1944                         jfs_error(bmp->db_ipbmap->i_sb,
1945                                   "I/O Error: Block Leakage\n");
1946                         continue;
1947                 }
1948                 dp = (struct dmap *) mp->data;
1949 
1950                 /* free the blocks is this dmap.
1951                  */
1952                 if (dbFreeDmap(bmp, dp, b, BPERDMAP)) {
1953                         /* could not back out.  mark the file system
1954                          * to indicate that we have leaked blocks.
1955                          */
1956                         release_metapage(mp);
1957                         jfs_error(bmp->db_ipbmap->i_sb, "Block Leakage\n");
1958                         continue;
1959                 }
1960 
1961                 /* write the buffer.
1962                  */
1963                 write_metapage(mp);
1964         }
1965 
1966         return (rc);
1967 }
1968 
1969 
1970 /*
1971  * NAME:        dbAllocDmapLev()
1972  *
1973  * FUNCTION:    attempt to allocate a specified number of contiguous blocks
1974  *              from a specified dmap.
1975  *
1976  *              this routine checks if the contiguous blocks are available.
1977  *              if so, nblocks of blocks are allocated; otherwise, ENOSPC is
1978  *              returned.
1979  *
1980  * PARAMETERS:
1981  *      mp      -  pointer to bmap descriptor
1982  *      dp      -  pointer to dmap to attempt to allocate blocks from.
1983  *      l2nb    -  log2 number of contiguous block desired.
1984  *      nblocks -  actual number of contiguous block desired.
1985  *      results -  on successful return, set to the starting block number
1986  *                 of the newly allocated range.
1987  *
1988  * RETURN VALUES:
1989  *      0       - success
1990  *      -ENOSPC - insufficient disk resources
1991  *      -EIO    - i/o error
1992  *
1993  * serialization: IREAD_LOCK(ipbmap), e.g., from dbAlloc(), or
1994  *      IWRITE_LOCK(ipbmap), e.g., dbAllocCtl(), held on entry/exit;
1995  */
1996 static int
1997 dbAllocDmapLev(struct bmap * bmp,
1998                struct dmap * dp, int nblocks, int l2nb, s64 * results)
1999 {
2000         s64 blkno;
2001         int leafidx, rc;
2002 
2003         /* can't be more than a dmaps worth of blocks */
2004         assert(l2nb <= L2BPERDMAP);
2005 
2006         /* search the tree within the dmap page for sufficient
2007          * free space.  if sufficient free space is found, dbFindLeaf()
2008          * returns the index of the leaf at which free space was found.
2009          */
2010         if (dbFindLeaf((dmtree_t *) & dp->tree, l2nb, &leafidx))
2011                 return -ENOSPC;
2012 
2013         /* determine the block number within the file system corresponding
2014          * to the leaf at which free space was found.
2015          */
2016         blkno = le64_to_cpu(dp->start) + (leafidx << L2DBWORD);
2017 
2018         /* if not all bits of the dmap word are free, get the starting
2019          * bit number within the dmap word of the required string of free
2020          * bits and adjust the block number with this value.
2021          */
2022         if (dp->tree.stree[leafidx + LEAFIND] < BUDMIN)
2023                 blkno += dbFindBits(le32_to_cpu(dp->wmap[leafidx]), l2nb);
2024 
2025         /* allocate the blocks */
2026         if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
2027                 *results = blkno;
2028 
2029         return (rc);
2030 }
2031 
2032 
2033 /*
2034  * NAME:        dbAllocDmap()
2035  *
2036  * FUNCTION:    adjust the disk allocation map to reflect the allocation
2037  *              of a specified block range within a dmap.
2038  *
2039  *              this routine allocates the specified blocks from the dmap
2040  *              through a call to dbAllocBits(). if the allocation of the
2041  *              block range causes the maximum string of free blocks within
2042  *              the dmap to change (i.e. the value of the root of the dmap's
2043  *              dmtree), this routine will cause this change to be reflected
2044  *              up through the appropriate levels of the dmap control pages
2045  *              by a call to dbAdjCtl() for the L0 dmap control page that
2046  *              covers this dmap.
2047  *
2048  * PARAMETERS:
2049  *      bmp     -  pointer to bmap descriptor
2050  *      dp      -  pointer to dmap to allocate the block range from.
2051  *      blkno   -  starting block number of the block to be allocated.
2052  *      nblocks -  number of blocks to be allocated.
2053  *
2054  * RETURN VALUES:
2055  *      0       - success
2056  *      -EIO    - i/o error
2057  *
2058  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2059  */
2060 static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2061                        int nblocks)
2062 {
2063         s8 oldroot;
2064         int rc;
2065 
2066         /* save the current value of the root (i.e. maximum free string)
2067          * of the dmap tree.
2068          */
2069         oldroot = dp->tree.stree[ROOT];
2070 
2071         /* allocate the specified (blocks) bits */
2072         dbAllocBits(bmp, dp, blkno, nblocks);
2073 
2074         /* if the root has not changed, done. */
2075         if (dp->tree.stree[ROOT] == oldroot)
2076                 return (0);
2077 
2078         /* root changed. bubble the change up to the dmap control pages.
2079          * if the adjustment of the upper level control pages fails,
2080          * backout the bit allocation (thus making everything consistent).
2081          */
2082         if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 1, 0)))
2083                 dbFreeBits(bmp, dp, blkno, nblocks);
2084 
2085         return (rc);
2086 }
2087 
2088 
2089 /*
2090  * NAME:        dbFreeDmap()
2091  *
2092  * FUNCTION:    adjust the disk allocation map to reflect the allocation
2093  *              of a specified block range within a dmap.
2094  *
2095  *              this routine frees the specified blocks from the dmap through
2096  *              a call to dbFreeBits(). if the deallocation of the block range
2097  *              causes the maximum string of free blocks within the dmap to
2098  *              change (i.e. the value of the root of the dmap's dmtree), this
2099  *              routine will cause this change to be reflected up through the
2100  *              appropriate levels of the dmap control pages by a call to
2101  *              dbAdjCtl() for the L0 dmap control page that covers this dmap.
2102  *
2103  * PARAMETERS:
2104  *      bmp     -  pointer to bmap descriptor
2105  *      dp      -  pointer to dmap to free the block range from.
2106  *      blkno   -  starting block number of the block to be freed.
2107  *      nblocks -  number of blocks to be freed.
2108  *
2109  * RETURN VALUES:
2110  *      0       - success
2111  *      -EIO    - i/o error
2112  *
2113  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2114  */
2115 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2116                       int nblocks)
2117 {
2118         s8 oldroot;
2119         int rc = 0, word;
2120 
2121         /* save the current value of the root (i.e. maximum free string)
2122          * of the dmap tree.
2123          */
2124         oldroot = dp->tree.stree[ROOT];
2125 
2126         /* free the specified (blocks) bits */
2127         rc = dbFreeBits(bmp, dp, blkno, nblocks);
2128 
2129         /* if error or the root has not changed, done. */
2130         if (rc || (dp->tree.stree[ROOT] == oldroot))
2131                 return (rc);
2132 
2133         /* root changed. bubble the change up to the dmap control pages.
2134          * if the adjustment of the upper level control pages fails,
2135          * backout the deallocation.
2136          */
2137         if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 0, 0))) {
2138                 word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
2139 
2140                 /* as part of backing out the deallocation, we will have
2141                  * to back split the dmap tree if the deallocation caused
2142                  * the freed blocks to become part of a larger binary buddy
2143                  * system.
2144                  */
2145                 if (dp->tree.stree[word] == NOFREE)
2146                         dbBackSplit((dmtree_t *) & dp->tree, word);
2147 
2148                 dbAllocBits(bmp, dp, blkno, nblocks);
2149         }
2150 
2151         return (rc);
2152 }
2153 
2154 
2155 /*
2156  * NAME:        dbAllocBits()
2157  *
2158  * FUNCTION:    allocate a specified block range from a dmap.
2159  *
2160  *              this routine updates the dmap to reflect the working
2161  *              state allocation of the specified block range. it directly
2162  *              updates the bits of the working map and causes the adjustment
2163  *              of the binary buddy system described by the dmap's dmtree
2164  *              leaves to reflect the bits allocated.  it also causes the
2165  *              dmap's dmtree, as a whole, to reflect the allocated range.
2166  *
2167  * PARAMETERS:
2168  *      bmp     -  pointer to bmap descriptor
2169  *      dp      -  pointer to dmap to allocate bits from.
2170  *      blkno   -  starting block number of the bits to be allocated.
2171  *      nblocks -  number of bits to be allocated.
2172  *
2173  * RETURN VALUES: none
2174  *
2175  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2176  */
2177 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2178                         int nblocks)
2179 {
2180         int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2181         dmtree_t *tp = (dmtree_t *) & dp->tree;
2182         int size;
2183         s8 *leaf;
2184 
2185         /* pick up a pointer to the leaves of the dmap tree */
2186         leaf = dp->tree.stree + LEAFIND;
2187 
2188         /* determine the bit number and word within the dmap of the
2189          * starting block.
2190          */
2191         dbitno = blkno & (BPERDMAP - 1);
2192         word = dbitno >> L2DBWORD;
2193 
2194         /* block range better be within the dmap */
2195         assert(dbitno + nblocks <= BPERDMAP);
2196 
2197         /* allocate the bits of the dmap's words corresponding to the block
2198          * range. not all bits of the first and last words may be contained
2199          * within the block range.  if this is the case, we'll work against
2200          * those words (i.e. partial first and/or last) on an individual basis
2201          * (a single pass), allocating the bits of interest by hand and
2202          * updating the leaf corresponding to the dmap word. a single pass
2203          * will be used for all dmap words fully contained within the
2204          * specified range.  within this pass, the bits of all fully contained
2205          * dmap words will be marked as free in a single shot and the leaves
2206          * will be updated. a single leaf may describe the free space of
2207          * multiple dmap words, so we may update only a subset of the actual
2208          * leaves corresponding to the dmap words of the block range.
2209          */
2210         for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2211                 /* determine the bit number within the word and
2212                  * the number of bits within the word.
2213                  */
2214                 wbitno = dbitno & (DBWORD - 1);
2215                 nb = min(rembits, DBWORD - wbitno);
2216 
2217                 /* check if only part of a word is to be allocated.
2218                  */
2219                 if (nb < DBWORD) {
2220                         /* allocate (set to 1) the appropriate bits within
2221                          * this dmap word.
2222                          */
2223                         dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
2224                                                       >> wbitno);
2225 
2226                         /* update the leaf for this dmap word. in addition
2227                          * to setting the leaf value to the binary buddy max
2228                          * of the updated dmap word, dbSplit() will split
2229                          * the binary system of the leaves if need be.
2230                          */
2231                         dbSplit(tp, word, BUDMIN,
2232                                 dbMaxBud((u8 *) & dp->wmap[word]));
2233 
2234                         word += 1;
2235                 } else {
2236                         /* one or more dmap words are fully contained
2237                          * within the block range.  determine how many
2238                          * words and allocate (set to 1) the bits of these
2239                          * words.
2240                          */
2241                         nwords = rembits >> L2DBWORD;
2242                         memset(&dp->wmap[word], (int) ONES, nwords * 4);
2243 
2244                         /* determine how many bits.
2245                          */
2246                         nb = nwords << L2DBWORD;
2247 
2248                         /* now update the appropriate leaves to reflect
2249                          * the allocated words.
2250                          */
2251                         for (; nwords > 0; nwords -= nw) {
2252                                 if (leaf[word] < BUDMIN) {
2253                                         jfs_error(bmp->db_ipbmap->i_sb,
2254                                                   "leaf page corrupt\n");
2255                                         break;
2256                                 }
2257 
2258                                 /* determine what the leaf value should be
2259                                  * updated to as the minimum of the l2 number
2260                                  * of bits being allocated and the l2 number
2261                                  * of bits currently described by this leaf.
2262                                  */
2263                                 size = min_t(int, leaf[word],
2264                                              NLSTOL2BSZ(nwords));
2265 
2266                                 /* update the leaf to reflect the allocation.
2267                                  * in addition to setting the leaf value to
2268                                  * NOFREE, dbSplit() will split the binary
2269                                  * system of the leaves to reflect the current
2270                                  * allocation (size).
2271                                  */
2272                                 dbSplit(tp, word, size, NOFREE);
2273 
2274                                 /* get the number of dmap words handled */
2275                                 nw = BUDSIZE(size, BUDMIN);
2276                                 word += nw;
2277                         }
2278                 }
2279         }
2280 
2281         /* update the free count for this dmap */
2282         le32_add_cpu(&dp->nfree, -nblocks);
2283 
2284         BMAP_LOCK(bmp);
2285 
2286         /* if this allocation group is completely free,
2287          * update the maximum allocation group number if this allocation
2288          * group is the new max.
2289          */
2290         agno = blkno >> bmp->db_agl2size;
2291         if (agno > bmp->db_maxag)
2292                 bmp->db_maxag = agno;
2293 
2294         /* update the free count for the allocation group and map */
2295         bmp->db_agfree[agno] -= nblocks;
2296         bmp->db_nfree -= nblocks;
2297 
2298         BMAP_UNLOCK(bmp);
2299 }
2300 
2301 
2302 /*
2303  * NAME:        dbFreeBits()
2304  *
2305  * FUNCTION:    free a specified block range from a dmap.
2306  *
2307  *              this routine updates the dmap to reflect the working
2308  *              state allocation of the specified block range. it directly
2309  *              updates the bits of the working map and causes the adjustment
2310  *              of the binary buddy system described by the dmap's dmtree
2311  *              leaves to reflect the bits freed.  it also causes the dmap's
2312  *              dmtree, as a whole, to reflect the deallocated range.
2313  *
2314  * PARAMETERS:
2315  *      bmp     -  pointer to bmap descriptor
2316  *      dp      -  pointer to dmap to free bits from.
2317  *      blkno   -  starting block number of the bits to be freed.
2318  *      nblocks -  number of bits to be freed.
2319  *
2320  * RETURN VALUES: 0 for success
2321  *
2322  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2323  */
2324 static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2325                        int nblocks)
2326 {
2327         int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2328         dmtree_t *tp = (dmtree_t *) & dp->tree;
2329         int rc = 0;
2330         int size;
2331 
2332         /* determine the bit number and word within the dmap of the
2333          * starting block.
2334          */
2335         dbitno = blkno & (BPERDMAP - 1);
2336         word = dbitno >> L2DBWORD;
2337 
2338         /* block range better be within the dmap.
2339          */
2340         assert(dbitno + nblocks <= BPERDMAP);
2341 
2342         /* free the bits of the dmaps words corresponding to the block range.
2343          * not all bits of the first and last words may be contained within
2344          * the block range.  if this is the case, we'll work against those
2345          * words (i.e. partial first and/or last) on an individual basis
2346          * (a single pass), freeing the bits of interest by hand and updating
2347          * the leaf corresponding to the dmap word. a single pass will be used
2348          * for all dmap words fully contained within the specified range.
2349          * within this pass, the bits of all fully contained dmap words will
2350          * be marked as free in a single shot and the leaves will be updated. a
2351          * single leaf may describe the free space of multiple dmap words,
2352          * so we may update only a subset of the actual leaves corresponding
2353          * to the dmap words of the block range.
2354          *
2355          * dbJoin() is used to update leaf values and will join the binary
2356          * buddy system of the leaves if the new leaf values indicate this
2357          * should be done.
2358          */
2359         for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2360                 /* determine the bit number within the word and
2361                  * the number of bits within the word.
2362                  */
2363                 wbitno = dbitno & (DBWORD - 1);
2364                 nb = min(rembits, DBWORD - wbitno);
2365 
2366                 /* check if only part of a word is to be freed.
2367                  */
2368                 if (nb < DBWORD) {
2369                         /* free (zero) the appropriate bits within this
2370                          * dmap word.
2371                          */
2372                         dp->wmap[word] &=
2373                             cpu_to_le32(~(ONES << (DBWORD - nb)
2374                                           >> wbitno));
2375 
2376                         /* update the leaf for this dmap word.
2377                          */
2378                         rc = dbJoin(tp, word,
2379                                     dbMaxBud((u8 *) & dp->wmap[word]));
2380                         if (rc)
2381                                 return rc;
2382 
2383                         word += 1;
2384                 } else {
2385                         /* one or more dmap words are fully contained
2386                          * within the block range.  determine how many
2387                          * words and free (zero) the bits of these words.
2388                          */
2389                         nwords = rembits >> L2DBWORD;
2390                         memset(&dp->wmap[word], 0, nwords * 4);
2391 
2392                         /* determine how many bits.
2393                          */
2394                         nb = nwords << L2DBWORD;
2395 
2396                         /* now update the appropriate leaves to reflect
2397                          * the freed words.
2398                          */
2399                         for (; nwords > 0; nwords -= nw) {
2400                                 /* determine what the leaf value should be
2401                                  * updated to as the minimum of the l2 number
2402                                  * of bits being freed and the l2 (max) number
2403                                  * of bits that can be described by this leaf.
2404                                  */
2405                                 size =
2406                                     min(LITOL2BSZ
2407                                         (word, L2LPERDMAP, BUDMIN),
2408                                         NLSTOL2BSZ(nwords));
2409 
2410                                 /* update the leaf.
2411                                  */
2412                                 rc = dbJoin(tp, word, size);
2413                                 if (rc)
2414                                         return rc;
2415 
2416                                 /* get the number of dmap words handled.
2417                                  */
2418                                 nw = BUDSIZE(size, BUDMIN);
2419                                 word += nw;
2420                         }
2421                 }
2422         }
2423 
2424         /* update the free count for this dmap.
2425          */
2426         le32_add_cpu(&dp->nfree, nblocks);
2427 
2428         BMAP_LOCK(bmp);
2429 
2430         /* update the free count for the allocation group and
2431          * map.
2432          */
2433         agno = blkno >> bmp->db_agl2size;
2434         bmp->db_nfree += nblocks;
2435         bmp->db_agfree[agno] += nblocks;
2436 
2437         /* check if this allocation group is not completely free and
2438          * if it is currently the maximum (rightmost) allocation group.
2439          * if so, establish the new maximum allocation group number by
2440          * searching left for the first allocation group with allocation.
2441          */
2442         if ((bmp->db_agfree[agno] == bmp->db_agsize && agno == bmp->db_maxag) ||
2443             (agno == bmp->db_numag - 1 &&
2444              bmp->db_agfree[agno] == (bmp-> db_mapsize & (BPERDMAP - 1)))) {
2445                 while (bmp->db_maxag > 0) {
2446                         bmp->db_maxag -= 1;
2447                         if (bmp->db_agfree[bmp->db_maxag] !=
2448                             bmp->db_agsize)
2449                                 break;
2450                 }
2451 
2452                 /* re-establish the allocation group preference if the
2453                  * current preference is right of the maximum allocation
2454                  * group.
2455                  */
2456                 if (bmp->db_agpref > bmp->db_maxag)
2457                         bmp->db_agpref = bmp->db_maxag;
2458         }
2459 
2460         BMAP_UNLOCK(bmp);
2461 
2462         return 0;
2463 }
2464 
2465 
2466 /*
2467  * NAME:        dbAdjCtl()
2468  *
2469  * FUNCTION:    adjust a dmap control page at a specified level to reflect
2470  *              the change in a lower level dmap or dmap control page's
2471  *              maximum string of free blocks (i.e. a change in the root
2472  *              of the lower level object's dmtree) due to the allocation
2473  *              or deallocation of a range of blocks with a single dmap.
2474  *
2475  *              on entry, this routine is provided with the new value of
2476  *              the lower level dmap or dmap control page root and the
2477  *              starting block number of the block range whose allocation
2478  *              or deallocation resulted in the root change.  this range
2479  *              is respresented by a single leaf of the current dmapctl
2480  *              and the leaf will be updated with this value, possibly
2481  *              causing a binary buddy system within the leaves to be
2482  *              split or joined.  the update may also cause the dmapctl's
2483  *              dmtree to be updated.
2484  *
2485  *              if the adjustment of the dmap control page, itself, causes its
2486  *              root to change, this change will be bubbled up to the next dmap
2487  *              control level by a recursive call to this routine, specifying
2488  *              the new root value and the next dmap control page level to
2489  *              be adjusted.
2490  * PARAMETERS:
2491  *      bmp     -  pointer to bmap descriptor
2492  *      blkno   -  the first block of a block range within a dmap.  it is
2493  *                 the allocation or deallocation of this block range that
2494  *                 requires the dmap control page to be adjusted.
2495  *      newval  -  the new value of the lower level dmap or dmap control
2496  *                 page root.
2497  *      alloc   -  'true' if adjustment is due to an allocation.
2498  *      level   -  current level of dmap control page (i.e. L0, L1, L2) to
2499  *                 be adjusted.
2500  *
2501  * RETURN VALUES:
2502  *      0       - success
2503  *      -EIO    - i/o error
2504  *
2505  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2506  */
2507 static int
2508 dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
2509 {
2510         struct metapage *mp;
2511         s8 oldroot;
2512         int oldval;
2513         s64 lblkno;
2514         struct dmapctl *dcp;
2515         int rc, leafno, ti;
2516 
2517         /* get the buffer for the dmap control page for the specified
2518          * block number and control page level.
2519          */
2520         lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, level);
2521         mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
2522         if (mp == NULL)
2523                 return -EIO;
2524         dcp = (struct dmapctl *) mp->data;
2525 
2526         if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
2527                 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page\n");
2528                 release_metapage(mp);
2529                 return -EIO;
2530         }
2531 
2532         /* determine the leaf number corresponding to the block and
2533          * the index within the dmap control tree.
2534          */
2535         leafno = BLKTOCTLLEAF(blkno, dcp->budmin);
2536         ti = leafno + le32_to_cpu(dcp->leafidx);
2537 
2538         /* save the current leaf value and the current root level (i.e.
2539          * maximum l2 free string described by this dmapctl).
2540          */
2541         oldval = dcp->stree[ti];
2542         oldroot = dcp->stree[ROOT];
2543 
2544         /* check if this is a control page update for an allocation.
2545          * if so, update the leaf to reflect the new leaf value using
2546          * dbSplit(); otherwise (deallocation), use dbJoin() to update
2547          * the leaf with the new value.  in addition to updating the
2548          * leaf, dbSplit() will also split the binary buddy system of
2549          * the leaves, if required, and bubble new values within the
2550          * dmapctl tree, if required.  similarly, dbJoin() will join
2551          * the binary buddy system of leaves and bubble new values up
2552          * the dmapctl tree as required by the new leaf value.
2553          */
2554         if (alloc) {
2555                 /* check if we are in the middle of a binary buddy
2556                  * system.  this happens when we are performing the
2557                  * first allocation out of an allocation group that
2558                  * is part (not the first part) of a larger binary
2559                  * buddy system.  if we are in the middle, back split
2560                  * the system prior to calling dbSplit() which assumes
2561                  * that it is at the front of a binary buddy system.
2562                  */
2563                 if (oldval == NOFREE) {
2564                         rc = dbBackSplit((dmtree_t *) dcp, leafno);
2565                         if (rc)
2566                                 return rc;
2567                         oldval = dcp->stree[ti];
2568                 }
2569                 dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval);
2570         } else {
2571                 rc = dbJoin((dmtree_t *) dcp, leafno, newval);
2572                 if (rc)
2573                         return rc;
2574         }
2575 
2576         /* check if the root of the current dmap control page changed due
2577          * to the update and if the current dmap control page is not at
2578          * the current top level (i.e. L0, L1, L2) of the map.  if so (i.e.
2579          * root changed and this is not the top level), call this routine
2580          * again (recursion) for the next higher level of the mapping to
2581          * reflect the change in root for the current dmap control page.
2582          */
2583         if (dcp->stree[ROOT] != oldroot) {
2584                 /* are we below the top level of the map.  if so,
2585                  * bubble the root up to the next higher level.
2586                  */
2587                 if (level < bmp->db_maxlevel) {
2588                         /* bubble up the new root of this dmap control page to
2589                          * the next level.
2590                          */
2591                         if ((rc =
2592                              dbAdjCtl(bmp, blkno, dcp->stree[ROOT], alloc,
2593                                       level + 1))) {
2594                                 /* something went wrong in bubbling up the new
2595                                  * root value, so backout the changes to the
2596                                  * current dmap control page.
2597                                  */
2598                                 if (alloc) {
2599                                         dbJoin((dmtree_t *) dcp, leafno,
2600                                                oldval);
2601                                 } else {
2602                                         /* the dbJoin() above might have
2603                                          * caused a larger binary buddy system
2604                                          * to form and we may now be in the
2605                                          * middle of it.  if this is the case,
2606                                          * back split the buddies.
2607                                          */
2608                                         if (dcp->stree[ti] == NOFREE)
2609                                                 dbBackSplit((dmtree_t *)
2610                                                             dcp, leafno);
2611                                         dbSplit((dmtree_t *) dcp, leafno,
2612                                                 dcp->budmin, oldval);
2613                                 }
2614 
2615                                 /* release the buffer and return the error.
2616                                  */
2617                                 release_metapage(mp);
2618                                 return (rc);
2619                         }
2620                 } else {
2621                         /* we're at the top level of the map. update
2622                          * the bmap control page to reflect the size
2623                          * of the maximum free buddy system.
2624                          */
2625                         assert(level == bmp->db_maxlevel);
2626                         if (bmp->db_maxfreebud != oldroot) {
2627                                 jfs_error(bmp->db_ipbmap->i_sb,
2628                                           "the maximum free buddy is not the old root\n");
2629                         }
2630                         bmp->db_maxfreebud = dcp->stree[ROOT];
2631                 }
2632         }
2633 
2634         /* write the buffer.
2635          */
2636         write_metapage(mp);
2637 
2638         return (0);
2639 }
2640 
2641 
2642 /*
2643  * NAME:        dbSplit()
2644  *
2645  * FUNCTION:    update the leaf of a dmtree with a new value, splitting
2646  *              the leaf from the binary buddy system of the dmtree's
2647  *              leaves, as required.
2648  *
2649  * PARAMETERS:
2650  *      tp      - pointer to the tree containing the leaf.
2651  *      leafno  - the number of the leaf to be updated.
2652  *      splitsz - the size the binary buddy system starting at the leaf
2653  *                must be split to, specified as the log2 number of blocks.
2654  *      newval  - the new value for the leaf.
2655  *
2656  * RETURN VALUES: none
2657  *
2658  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2659  */
2660 static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
2661 {
2662         int budsz;
2663         int cursz;
2664         s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2665 
2666         /* check if the leaf needs to be split.
2667          */
2668         if (leaf[leafno] > tp->dmt_budmin) {
2669                 /* the split occurs by cutting the buddy system in half
2670                  * at the specified leaf until we reach the specified
2671                  * size.  pick up the starting split size (current size
2672                  * - 1 in l2) and the corresponding buddy size.
2673                  */
2674                 cursz = leaf[leafno] - 1;
2675                 budsz = BUDSIZE(cursz, tp->dmt_budmin);
2676 
2677                 /* split until we reach the specified size.
2678                  */
2679                 while (cursz >= splitsz) {
2680                         /* update the buddy's leaf with its new value.
2681                          */
2682                         dbAdjTree(tp, leafno ^ budsz, cursz);
2683 
2684                         /* on to the next size and buddy.
2685                          */
2686                         cursz -= 1;
2687                         budsz >>= 1;
2688                 }
2689         }
2690 
2691         /* adjust the dmap tree to reflect the specified leaf's new
2692          * value.
2693          */
2694         dbAdjTree(tp, leafno, newval);
2695 }
2696 
2697 
2698 /*
2699  * NAME:        dbBackSplit()
2700  *
2701  * FUNCTION:    back split the binary buddy system of dmtree leaves
2702  *              that hold a specified leaf until the specified leaf
2703  *              starts its own binary buddy system.
2704  *
2705  *              the allocators typically perform allocations at the start
2706  *              of binary buddy systems and dbSplit() is used to accomplish
2707  *              any required splits.  in some cases, however, allocation
2708  *              may occur in the middle of a binary system and requires a
2709  *              back split, with the split proceeding out from the middle of
2710  *              the system (less efficient) rather than the start of the
2711  *              system (more efficient).  the cases in which a back split
2712  *              is required are rare and are limited to the first allocation
2713  *              within an allocation group which is a part (not first part)
2714  *              of a larger binary buddy system and a few exception cases
2715  *              in which a previous join operation must be backed out.
2716  *
2717  * PARAMETERS:
2718  *      tp      - pointer to the tree containing the leaf.
2719  *      leafno  - the number of the leaf to be updated.
2720  *
2721  * RETURN VALUES: none
2722  *
2723  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2724  */
2725 static int dbBackSplit(dmtree_t * tp, int leafno)
2726 {
2727         int budsz, bud, w, bsz, size;
2728         int cursz;
2729         s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2730 
2731         /* leaf should be part (not first part) of a binary
2732          * buddy system.
2733          */
2734         assert(leaf[leafno] == NOFREE);
2735 
2736         /* the back split is accomplished by iteratively finding the leaf
2737          * that starts the buddy system that contains the specified leaf and
2738          * splitting that system in two.  this iteration continues until
2739          * the specified leaf becomes the start of a buddy system.
2740          *
2741          * determine maximum possible l2 size for the specified leaf.
2742          */
2743         size =
2744             LITOL2BSZ(leafno, le32_to_cpu(tp->dmt_l2nleafs),
2745                       tp->dmt_budmin);
2746 
2747         /* determine the number of leaves covered by this size.  this
2748          * is the buddy size that we will start with as we search for
2749          * the buddy system that contains the specified leaf.
2750          */
2751         budsz = BUDSIZE(size, tp->dmt_budmin);
2752 
2753         /* back split.
2754          */
2755         while (leaf[leafno] == NOFREE) {
2756                 /* find the leftmost buddy leaf.
2757                  */
2758                 for (w = leafno, bsz = budsz;; bsz <<= 1,
2759                      w = (w < bud) ? w : bud) {
2760                         if (bsz >= le32_to_cpu(tp->dmt_nleafs)) {
2761                                 jfs_err("JFS: block map error in dbBackSplit");
2762                                 return -EIO;
2763                         }
2764 
2765                         /* determine the buddy.
2766                          */
2767                         bud = w ^ bsz;
2768 
2769                         /* check if this buddy is the start of the system.
2770                          */
2771                         if (leaf[bud] != NOFREE) {
2772                                 /* split the leaf at the start of the
2773                                  * system in two.
2774                                  */
2775                                 cursz = leaf[bud] - 1;
2776                                 dbSplit(tp, bud, cursz, cursz);
2777                                 break;
2778                         }
2779                 }
2780         }
2781 
2782         if (leaf[leafno] != size) {
2783                 jfs_err("JFS: wrong leaf value in dbBackSplit");
2784                 return -EIO;
2785         }
2786         return 0;
2787 }
2788 
2789 
2790 /*
2791  * NAME:        dbJoin()
2792  *
2793  * FUNCTION:    update the leaf of a dmtree with a new value, joining
2794  *              the leaf with other leaves of the dmtree into a multi-leaf
2795  *              binary buddy system, as required.
2796  *
2797  * PARAMETERS:
2798  *      tp      - pointer to the tree containing the leaf.
2799  *      leafno  - the number of the leaf to be updated.
2800  *      newval  - the new value for the leaf.
2801  *
2802  * RETURN VALUES: none
2803  */
2804 static int dbJoin(dmtree_t * tp, int leafno, int newval)
2805 {
2806         int budsz, buddy;
2807         s8 *leaf;
2808 
2809         /* can the new leaf value require a join with other leaves ?
2810          */
2811         if (newval >= tp->dmt_budmin) {
2812                 /* pickup a pointer to the leaves of the tree.
2813                  */
2814                 leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2815 
2816                 /* try to join the specified leaf into a large binary
2817                  * buddy system.  the join proceeds by attempting to join
2818                  * the specified leafno with its buddy (leaf) at new value.
2819                  * if the join occurs, we attempt to join the left leaf
2820                  * of the joined buddies with its buddy at new value + 1.
2821                  * we continue to join until we find a buddy that cannot be
2822                  * joined (does not have a value equal to the size of the
2823                  * last join) or until all leaves have been joined into a
2824                  * single system.
2825                  *
2826                  * get the buddy size (number of words covered) of
2827                  * the new value.
2828                  */
2829                 budsz = BUDSIZE(newval, tp->dmt_budmin);
2830 
2831                 /* try to join.
2832                  */
2833                 while (budsz < le32_to_cpu(tp->dmt_nleafs)) {
2834                         /* get the buddy leaf.
2835                          */
2836                         buddy = leafno ^ budsz;
2837 
2838                         /* if the leaf's new value is greater than its
2839                          * buddy's value, we join no more.
2840                          */
2841                         if (newval > leaf[buddy])
2842                                 break;
2843 
2844                         /* It shouldn't be less */
2845                         if (newval < leaf[buddy])
2846                                 return -EIO;
2847 
2848                         /* check which (leafno or buddy) is the left buddy.
2849                          * the left buddy gets to claim the blocks resulting
2850                          * from the join while the right gets to claim none.
2851                          * the left buddy is also eligible to participate in
2852                          * a join at the next higher level while the right
2853                          * is not.
2854                          *
2855                          */
2856                         if (leafno < buddy) {
2857                                 /* leafno is the left buddy.
2858                                  */
2859                                 dbAdjTree(tp, buddy, NOFREE);
2860                         } else {
2861                                 /* buddy is the left buddy and becomes
2862                                  * leafno.
2863                                  */
2864                                 dbAdjTree(tp, leafno, NOFREE);
2865                                 leafno = buddy;
2866                         }
2867 
2868                         /* on to try the next join.
2869                          */
2870                         newval += 1;
2871                         budsz <<= 1;
2872                 }
2873         }
2874 
2875         /* update the leaf value.
2876          */
2877         dbAdjTree(tp, leafno, newval);
2878 
2879         return 0;
2880 }
2881 
2882 
2883 /*
2884  * NAME:        dbAdjTree()
2885  *
2886  * FUNCTION:    update a leaf of a dmtree with a new value, adjusting
2887  *              the dmtree, as required, to reflect the new leaf value.
2888  *              the combination of any buddies must already be done before
2889  *              this is called.
2890  *
2891  * PARAMETERS:
2892  *      tp      - pointer to the tree to be adjusted.
2893  *      leafno  - the number of the leaf to be updated.
2894  *      newval  - the new value for the leaf.
2895  *
2896  * RETURN VALUES: none
2897  */
2898 static void dbAdjTree(dmtree_t * tp, int leafno, int newval)
2899 {
2900         int lp, pp, k;
2901         int max;
2902 
2903         /* pick up the index of the leaf for this leafno.
2904          */
2905         lp = leafno + le32_to_cpu(tp->dmt_leafidx);
2906 
2907         /* is the current value the same as the old value ?  if so,
2908          * there is nothing to do.
2909          */
2910         if (tp->dmt_stree[lp] == newval)
2911                 return;
2912 
2913         /* set the new value.
2914          */
2915         tp->dmt_stree[lp] = newval;
2916 
2917         /* bubble the new value up the tree as required.
2918          */
2919         for (k = 0; k < le32_to_cpu(tp->dmt_height); k++) {
2920                 /* get the index of the first leaf of the 4 leaf
2921                  * group containing the specified leaf (leafno).
2922                  */
2923                 lp = ((lp - 1) & ~0x03) + 1;
2924 
2925                 /* get the index of the parent of this 4 leaf group.
2926                  */
2927                 pp = (lp - 1) >> 2;
2928 
2929                 /* determine the maximum of the 4 leaves.
2930                  */
2931                 max = TREEMAX(&tp->dmt_stree[lp]);
2932 
2933                 /* if the maximum of the 4 is the same as the
2934                  * parent's value, we're done.
2935                  */
2936                 if (tp->dmt_stree[pp] == max)
2937                         break;
2938 
2939                 /* parent gets new value.
2940                  */
2941                 tp->dmt_stree[pp] = max;
2942 
2943                 /* parent becomes leaf for next go-round.
2944                  */
2945                 lp = pp;
2946         }
2947 }
2948 
2949 
2950 /*
2951  * NAME:        dbFindLeaf()
2952  *
2953  * FUNCTION:    search a dmtree_t for sufficient free blocks, returning
2954  *              the index of a leaf describing the free blocks if
2955  *              sufficient free blocks are found.
2956  *
2957  *              the search starts at the top of the dmtree_t tree and
2958  *              proceeds down the tree to the leftmost leaf with sufficient
2959  *              free space.
2960  *
2961  * PARAMETERS:
2962  *      tp      - pointer to the tree to be searched.
2963  *      l2nb    - log2 number of free blocks to search for.
2964  *      leafidx - return pointer to be set to the index of the leaf
2965  *                describing at least l2nb free blocks if sufficient
2966  *                free blocks are found.
2967  *
2968  * RETURN VALUES:
2969  *      0       - success
2970  *      -ENOSPC - insufficient free blocks.
2971  */
2972 static int dbFindLeaf(dmtree_t * tp, int l2nb, int *leafidx)
2973 {
2974         int ti, n = 0, k, x = 0;
2975 
2976         /* first check the root of the tree to see if there is
2977          * sufficient free space.
2978          */
2979         if (l2nb > tp->dmt_stree[ROOT])
2980                 return -ENOSPC;
2981 
2982         /* sufficient free space available. now search down the tree
2983          * starting at the next level for the leftmost leaf that
2984          * describes sufficient free space.
2985          */
2986         for (k = le32_to_cpu(tp->dmt_height), ti = 1;
2987              k > 0; k--, ti = ((ti + n) << 2) + 1) {
2988                 /* search the four nodes at this level, starting from
2989                  * the left.
2990                  */
2991                 for (x = ti, n = 0; n < 4; n++) {
2992                         /* sufficient free space found.  move to the next
2993                          * level (or quit if this is the last level).
2994                          */
2995                         if (l2nb <= tp->dmt_stree[x + n])
2996                                 break;
2997                 }
2998 
2999                 /* better have found something since the higher
3000                  * levels of the tree said it was here.
3001                  */
3002                 assert(n < 4);
3003         }
3004 
3005         /* set the return to the leftmost leaf describing sufficient
3006          * free space.
3007          */
3008         *leafidx = x + n - le32_to_cpu(tp->dmt_leafidx);
3009 
3010         return (0);
3011 }
3012 
3013 
3014 /*
3015  * NAME:        dbFindBits()
3016  *
3017  * FUNCTION:    find a specified number of binary buddy free bits within a
3018  *              dmap bitmap word value.
3019  *
3020  *              this routine searches the bitmap value for (1 << l2nb) free
3021  *              bits at (1 << l2nb) alignments within the value.
3022  *
3023  * PARAMETERS:
3024  *      word    -  dmap bitmap word value.
3025  *      l2nb    -  number of free bits specified as a log2 number.
3026  *
3027  * RETURN VALUES:
3028  *      starting bit number of free bits.
3029  */
3030 static int dbFindBits(u32 word, int l2nb)
3031 {
3032         int bitno, nb;
3033         u32 mask;
3034 
3035         /* get the number of bits.
3036          */
3037         nb = 1 << l2nb;
3038         assert(nb <= DBWORD);
3039 
3040         /* complement the word so we can use a mask (i.e. 0s represent
3041          * free bits) and compute the mask.
3042          */
3043         word = ~word;
3044         mask = ONES << (DBWORD - nb);
3045 
3046         /* scan the word for nb free bits at nb alignments.
3047          */
3048         for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
3049                 if ((mask & word) == mask)
3050                         break;
3051         }
3052 
3053         ASSERT(bitno < 32);
3054 
3055         /* return the bit number.
3056          */
3057         return (bitno);
3058 }
3059 
3060 
3061 /*
3062  * NAME:        dbMaxBud(u8 *cp)
3063  *
3064  * FUNCTION:    determine the largest binary buddy string of free
3065  *              bits within 32-bits of the map.
3066  *
3067  * PARAMETERS:
3068  *      cp      -  pointer to the 32-bit value.
3069  *
3070  * RETURN VALUES:
3071  *      largest binary buddy of free bits within a dmap word.
3072  */
3073 static int dbMaxBud(u8 * cp)
3074 {
3075         signed char tmp1, tmp2;
3076 
3077         /* check if the wmap word is all free. if so, the
3078          * free buddy size is BUDMIN.
3079          */
3080         if (*((uint *) cp) == 0)
3081                 return (BUDMIN);
3082 
3083         /* check if the wmap word is half free. if so, the
3084          * free buddy size is BUDMIN-1.
3085          */
3086         if (*((u16 *) cp) == 0 || *((u16 *) cp + 1) == 0)
3087                 return (BUDMIN - 1);
3088 
3089         /* not all free or half free. determine the free buddy
3090          * size thru table lookup using quarters of the wmap word.
3091          */
3092         tmp1 = max(budtab[cp[2]], budtab[cp[3]]);
3093         tmp2 = max(budtab[cp[0]], budtab[cp[1]]);
3094         return (max(tmp1, tmp2));
3095 }
3096 
3097 
3098 /*
3099  * NAME:        cnttz(uint word)
3100  *
3101  * FUNCTION:    determine the number of trailing zeros within a 32-bit
3102  *              value.
3103  *
3104  * PARAMETERS:
3105  *      value   -  32-bit value to be examined.
3106  *
3107  * RETURN VALUES:
3108  *      count of trailing zeros
3109  */
3110 static int cnttz(u32 word)
3111 {
3112         int n;
3113 
3114         for (n = 0; n < 32; n++, word >>= 1) {
3115                 if (word & 0x01)
3116                         break;
3117         }
3118 
3119         return (n);
3120 }
3121 
3122 
3123 /*
3124  * NAME:        cntlz(u32 value)
3125  *
3126  * FUNCTION:    determine the number of leading zeros within a 32-bit
3127  *              value.
3128  *
3129  * PARAMETERS:
3130  *      value   -  32-bit value to be examined.
3131  *
3132  * RETURN VALUES:
3133  *      count of leading zeros
3134  */
3135 static int cntlz(u32 value)
3136 {
3137         int n;
3138 
3139         for (n = 0; n < 32; n++, value <<= 1) {
3140                 if (value & HIGHORDER)
3141                         break;
3142         }
3143         return (n);
3144 }
3145 
3146 
3147 /*
3148  * NAME:        blkstol2(s64 nb)
3149  *
3150  * FUNCTION:    convert a block count to its log2 value. if the block
3151  *              count is not a l2 multiple, it is rounded up to the next
3152  *              larger l2 multiple.
3153  *
3154  * PARAMETERS:
3155  *      nb      -  number of blocks
3156  *
3157  * RETURN VALUES:
3158  *      log2 number of blocks
3159  */
3160 static int blkstol2(s64 nb)
3161 {
3162         int l2nb;
3163         s64 mask;               /* meant to be signed */
3164 
3165         mask = (s64) 1 << (64 - 1);
3166 
3167         /* count the leading bits.
3168          */
3169         for (l2nb = 0; l2nb < 64; l2nb++, mask >>= 1) {
3170                 /* leading bit found.
3171                  */
3172                 if (nb & mask) {
3173                         /* determine the l2 value.
3174                          */
3175                         l2nb = (64 - 1) - l2nb;
3176 
3177                         /* check if we need to round up.
3178                          */
3179                         if (~mask & nb)
3180                                 l2nb++;
3181 
3182                         return (l2nb);
3183                 }
3184         }
3185         assert(0);
3186         return 0;               /* fix compiler warning */
3187 }
3188 
3189 
3190 /*
3191  * NAME:        dbAllocBottomUp()
3192  *
3193  * FUNCTION:    alloc the specified block range from the working block
3194  *              allocation map.
3195  *
3196  *              the blocks will be alloc from the working map one dmap
3197  *              at a time.
3198  *
3199  * PARAMETERS:
3200  *      ip      -  pointer to in-core inode;
3201  *      blkno   -  starting block number to be freed.
3202  *      nblocks -  number of blocks to be freed.
3203  *
3204  * RETURN VALUES:
3205  *      0       - success
3206  *      -EIO    - i/o error
3207  */
3208 int dbAllocBottomUp(struct inode *ip, s64 blkno, s64 nblocks)
3209 {
3210         struct metapage *mp;
3211         struct dmap *dp;
3212         int nb, rc;
3213         s64 lblkno, rem;
3214         struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
3215         struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
3216 
3217         IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
3218 
3219         /* block to be allocated better be within the mapsize. */
3220         ASSERT(nblocks <= bmp->db_mapsize - blkno);
3221 
3222         /*
3223          * allocate the blocks a dmap at a time.
3224          */
3225         mp = NULL;
3226         for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
3227                 /* release previous dmap if any */
3228                 if (mp) {
3229                         write_metapage(mp);
3230                 }
3231 
3232                 /* get the buffer for the current dmap. */
3233                 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
3234                 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
3235                 if (mp == NULL) {
3236                         IREAD_UNLOCK(ipbmap);
3237                         return -EIO;
3238                 }
3239                 dp = (struct dmap *) mp->data;
3240 
3241                 /* determine the number of blocks to be allocated from
3242                  * this dmap.
3243                  */
3244                 nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
3245 
3246                 /* allocate the blocks. */
3247                 if ((rc = dbAllocDmapBU(bmp, dp, blkno, nb))) {
3248                         release_metapage(mp);
3249                         IREAD_UNLOCK(ipbmap);
3250                         return (rc);
3251                 }
3252         }
3253 
3254         /* write the last buffer. */
3255         write_metapage(mp);
3256 
3257         IREAD_UNLOCK(ipbmap);
3258 
3259         return (0);
3260 }
3261 
3262 
3263 static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
3264                          int nblocks)
3265 {
3266         int rc;
3267         int dbitno, word, rembits, nb, nwords, wbitno, agno;
3268         s8 oldroot;
3269         struct dmaptree *tp = (struct dmaptree *) & dp->tree;
3270 
3271         /* save the current value of the root (i.e. maximum free string)
3272          * of the dmap tree.
3273          */
3274         oldroot = tp->stree[ROOT];
3275 
3276         /* determine the bit number and word within the dmap of the
3277          * starting block.
3278          */
3279         dbitno = blkno & (BPERDMAP - 1);
3280         word = dbitno >> L2DBWORD;
3281 
3282         /* block range better be within the dmap */
3283         assert(dbitno + nblocks <= BPERDMAP);
3284 
3285         /* allocate the bits of the dmap's words corresponding to the block
3286          * range. not all bits of the first and last words may be contained
3287          * within the block range.  if this is the case, we'll work against
3288          * those words (i.e. partial first and/or last) on an individual basis
3289          * (a single pass), allocating the bits of interest by hand and
3290          * updating the leaf corresponding to the dmap word. a single pass
3291          * will be used for all dmap words fully contained within the
3292          * specified range.  within this pass, the bits of all fully contained
3293          * dmap words will be marked as free in a single shot and the leaves
3294          * will be updated. a single leaf may describe the free space of
3295          * multiple dmap words, so we may update only a subset of the actual
3296          * leaves corresponding to the dmap words of the block range.
3297          */
3298         for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
3299                 /* determine the bit number within the word and
3300                  * the number of bits within the word.
3301                  */
3302                 wbitno = dbitno & (DBWORD - 1);
3303                 nb = min(rembits, DBWORD - wbitno);
3304 
3305                 /* check if only part of a word is to be allocated.
3306                  */
3307                 if (nb < DBWORD) {
3308                         /* allocate (set to 1) the appropriate bits within
3309                          * this dmap word.
3310                          */
3311                         dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
3312                                                       >> wbitno);
3313 
3314                         word++;
3315                 } else {
3316                         /* one or more dmap words are fully contained
3317                          * within the block range.  determine how many
3318                          * words and allocate (set to 1) the bits of these
3319                          * words.
3320                          */
3321                         nwords = rembits >> L2DBWORD;
3322                         memset(&dp->wmap[word], (int) ONES, nwords * 4);
3323 
3324                         /* determine how many bits */
3325                         nb = nwords << L2DBWORD;
3326                         word += nwords;
3327                 }
3328         }
3329 
3330         /* update the free count for this dmap */
3331         le32_add_cpu(&dp->nfree, -nblocks);
3332 
3333         /* reconstruct summary tree */
3334         dbInitDmapTree(dp);
3335 
3336         BMAP_LOCK(bmp);
3337 
3338         /* if this allocation group is completely free,
3339          * update the highest active allocation group number
3340          * if this allocation group is the new max.
3341          */
3342         agno = blkno >> bmp->db_agl2size;
3343         if (agno > bmp->db_maxag)
3344                 bmp->db_maxag = agno;
3345 
3346         /* update the free count for the allocation group and map */
3347         bmp->db_agfree[agno] -= nblocks;
3348         bmp->db_nfree -= nblocks;
3349 
3350         BMAP_UNLOCK(bmp);
3351 
3352         /* if the root has not changed, done. */
3353         if (tp->stree[ROOT] == oldroot)
3354                 return (0);
3355 
3356         /* root changed. bubble the change up to the dmap control pages.
3357          * if the adjustment of the upper level control pages fails,
3358          * backout the bit allocation (thus making everything consistent).
3359          */
3360         if ((rc = dbAdjCtl(bmp, blkno, tp->stree[ROOT], 1, 0)))
3361                 dbFreeBits(bmp, dp, blkno, nblocks);
3362 
3363         return (rc);
3364 }
3365 
3366 
3367 /*
3368  * NAME:        dbExtendFS()
3369  *
3370  * FUNCTION:    extend bmap from blkno for nblocks;
3371  *              dbExtendFS() updates bmap ready for dbAllocBottomUp();
3372  *
3373  * L2
3374  *  |
3375  *   L1---------------------------------L1
3376  *    |                                  |
3377  *     L0---------L0---------L0           L0---------L0---------L0
3378  *      |          |          |            |          |          |
3379  *       d0,...,dn  d0,...,dn  d0,...,dn    d0,...,dn  d0,...,dn  d0,.,dm;
3380  * L2L1L0d0,...,dnL0d0,...,dnL0d0,...,dnL1L0d0,...,dnL0d0,...,dnL0d0,..dm
3381  *
3382  * <---old---><----------------------------extend----------------------->
3383  */
3384 int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks)
3385 {
3386         struct jfs_sb_info *sbi = JFS_SBI(ipbmap->i_sb);
3387         int nbperpage = sbi->nbperpage;
3388         int i, i0 = true, j, j0 = true, k, n;
3389         s64 newsize;
3390         s64 p;
3391         struct metapage *mp, *l2mp, *l1mp = NULL, *l0mp = NULL;
3392         struct dmapctl *l2dcp, *l1dcp, *l0dcp;
3393         struct dmap *dp;
3394         s8 *l0leaf, *l1leaf, *l2leaf;
3395         struct bmap *bmp = sbi->bmap;
3396         int agno, l2agsize, oldl2agsize;
3397         s64 ag_rem;
3398 
3399         newsize = blkno + nblocks;
3400 
3401         jfs_info("dbExtendFS: blkno:%Ld nblocks:%Ld newsize:%Ld",
3402                  (long long) blkno, (long long) nblocks, (long long) newsize);
3403 
3404         /*
3405          *      initialize bmap control page.
3406          *
3407          * all the data in bmap control page should exclude
3408          * the mkfs hidden dmap page.
3409          */
3410 
3411         /* update mapsize */
3412         bmp->db_mapsize = newsize;
3413         bmp->db_maxlevel = BMAPSZTOLEV(bmp->db_mapsize);
3414 
3415         /* compute new AG size */
3416         l2agsize = dbGetL2AGSize(newsize);
3417         oldl2agsize = bmp->db_agl2size;
3418 
3419         bmp->db_agl2size = l2agsize;
3420         bmp->db_agsize = 1 << l2agsize;
3421 
3422         /* compute new number of AG */
3423         agno = bmp->db_numag;
3424         bmp->db_numag = newsize >> l2agsize;
3425         bmp->db_numag += ((u32) newsize % (u32) bmp->db_agsize) ? 1 : 0;
3426 
3427         /*
3428          *      reconfigure db_agfree[]
3429          * from old AG configuration to new AG configuration;
3430          *
3431          * coalesce contiguous k (newAGSize/oldAGSize) AGs;
3432          * i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
3433          * note: new AG size = old AG size * (2**x).
3434          */
3435         if (l2agsize == oldl2agsize)
3436                 goto extend;
3437         k = 1 << (l2agsize - oldl2agsize);
3438         ag_rem = bmp->db_agfree[0];     /* save agfree[0] */
3439         for (i = 0, n = 0; i < agno; n++) {
3440                 bmp->db_agfree[n] = 0;  /* init collection point */
3441 
3442                 /* coalesce contiguous k AGs; */
3443                 for (j = 0; j < k && i < agno; j++, i++) {
3444                         /* merge AGi to AGn */
3445                         bmp->db_agfree[n] += bmp->db_agfree[i];
3446                 }
3447         }
3448         bmp->db_agfree[0] += ag_rem;    /* restore agfree[0] */
3449 
3450         for (; n < MAXAG; n++)
3451                 bmp->db_agfree[n] = 0;
3452 
3453         /*
3454          * update highest active ag number
3455          */
3456 
3457         bmp->db_maxag = bmp->db_maxag / k;
3458 
3459         /*
3460          *      extend bmap
3461          *
3462          * update bit maps and corresponding level control pages;
3463          * global control page db_nfree, db_agfree[agno], db_maxfreebud;
3464          */
3465       extend:
3466         /* get L2 page */
3467         p = BMAPBLKNO + nbperpage;      /* L2 page */
3468         l2mp = read_metapage(ipbmap, p, PSIZE, 0);
3469         if (!l2mp) {
3470                 jfs_error(ipbmap->i_sb, "L2 page could not be read\n");
3471                 return -EIO;
3472         }
3473         l2dcp = (struct dmapctl *) l2mp->data;
3474 
3475         /* compute start L1 */
3476         k = blkno >> L2MAXL1SIZE;
3477         l2leaf = l2dcp->stree + CTLLEAFIND + k;
3478         p = BLKTOL1(blkno, sbi->l2nbperpage);   /* L1 page */
3479 
3480         /*
3481          * extend each L1 in L2
3482          */
3483         for (; k < LPERCTL; k++, p += nbperpage) {
3484                 /* get L1 page */
3485                 if (j0) {
3486                         /* read in L1 page: (blkno & (MAXL1SIZE - 1)) */
3487                         l1mp = read_metapage(ipbmap, p, PSIZE, 0);
3488                         if (l1mp == NULL)
3489                                 goto errout;
3490                         l1dcp = (struct dmapctl *) l1mp->data;
3491 
3492                         /* compute start L0 */
3493                         j = (blkno & (MAXL1SIZE - 1)) >> L2MAXL0SIZE;
3494                         l1leaf = l1dcp->stree + CTLLEAFIND + j;
3495                         p = BLKTOL0(blkno, sbi->l2nbperpage);
3496                         j0 = false;
3497                 } else {
3498                         /* assign/init L1 page */
3499                         l1mp = get_metapage(ipbmap, p, PSIZE, 0);
3500                         if (l1mp == NULL)
3501                                 goto errout;
3502 
3503                         l1dcp = (struct dmapctl *) l1mp->data;
3504 
3505                         /* compute start L0 */
3506                         j = 0;
3507                         l1leaf = l1dcp->stree + CTLLEAFIND;
3508                         p += nbperpage; /* 1st L0 of L1.k */
3509                 }
3510 
3511                 /*
3512                  * extend each L0 in L1
3513                  */
3514                 for (; j < LPERCTL; j++) {
3515                         /* get L0 page */
3516                         if (i0) {
3517                                 /* read in L0 page: (blkno & (MAXL0SIZE - 1)) */
3518 
3519                                 l0mp = read_metapage(ipbmap, p, PSIZE, 0);
3520                                 if (l0mp == NULL)
3521                                         goto errout;
3522                                 l0dcp = (struct dmapctl *) l0mp->data;
3523 
3524                                 /* compute start dmap */
3525                                 i = (blkno & (MAXL0SIZE - 1)) >>
3526                                     L2BPERDMAP;
3527                                 l0leaf = l0dcp->stree + CTLLEAFIND + i;
3528                                 p = BLKTODMAP(blkno,
3529                                               sbi->l2nbperpage);
3530                                 i0 = false;
3531                         } else {
3532                                 /* assign/init L0 page */
3533                                 l0mp = get_metapage(ipbmap, p, PSIZE, 0);
3534                                 if (l0mp == NULL)
3535                                         goto errout;
3536 
3537                                 l0dcp = (struct dmapctl *) l0mp->data;
3538 
3539                                 /* compute start dmap */
3540                                 i = 0;
3541                                 l0leaf = l0dcp->stree + CTLLEAFIND;
3542                                 p += nbperpage; /* 1st dmap of L0.j */
3543                         }
3544 
3545                         /*
3546                          * extend each dmap in L0
3547                          */
3548                         for (; i < LPERCTL; i++) {
3549                                 /*
3550                                  * reconstruct the dmap page, and
3551                                  * initialize corresponding parent L0 leaf
3552                                  */
3553                                 if ((n = blkno & (BPERDMAP - 1))) {
3554                                         /* read in dmap page: */
3555                                         mp = read_metapage(ipbmap, p,
3556                                                            PSIZE, 0);
3557                                         if (mp == NULL)
3558                                                 goto errout;
3559                                         n = min(nblocks, (s64)BPERDMAP - n);
3560                                 } else {
3561                                         /* assign/init dmap page */
3562                                         mp = read_metapage(ipbmap, p,
3563                                                            PSIZE, 0);
3564                                         if (mp == NULL)
3565                                                 goto errout;
3566 
3567                                         n = min_t(s64, nblocks, BPERDMAP);
3568                                 }
3569 
3570                                 dp = (struct dmap *) mp->data;
3571                                 *l0leaf = dbInitDmap(dp, blkno, n);
3572 
3573                                 bmp->db_nfree += n;
3574                                 agno = le64_to_cpu(dp->start) >> l2agsize;
3575                                 bmp->db_agfree[agno] += n;
3576 
3577                                 write_metapage(mp);
3578 
3579                                 l0leaf++;
3580                                 p += nbperpage;
3581 
3582                                 blkno += n;
3583                                 nblocks -= n;
3584                                 if (nblocks == 0)
3585                                         break;
3586                         }       /* for each dmap in a L0 */
3587 
3588                         /*
3589                          * build current L0 page from its leaves, and
3590                          * initialize corresponding parent L1 leaf
3591                          */
3592                         *l1leaf = dbInitDmapCtl(l0dcp, 0, ++i);
3593                         write_metapage(l0mp);
3594                         l0mp = NULL;
3595 
3596                         if (nblocks)
3597                                 l1leaf++;       /* continue for next L0 */
3598                         else {
3599                                 /* more than 1 L0 ? */
3600                                 if (j > 0)
3601                                         break;  /* build L1 page */
3602                                 else {
3603                                         /* summarize in global bmap page */
3604                                         bmp->db_maxfreebud = *l1leaf;
3605                                         release_metapage(l1mp);
3606                                         release_metapage(l2mp);
3607                                         goto finalize;
3608                                 }
3609                         }
3610                 }               /* for each L0 in a L1 */
3611 
3612                 /*
3613                  * build current L1 page from its leaves, and
3614                  * initialize corresponding parent L2 leaf
3615                  */
3616                 *l2leaf = dbInitDmapCtl(l1dcp, 1, ++j);
3617                 write_metapage(l1mp);
3618                 l1mp = NULL;
3619 
3620                 if (nblocks)
3621                         l2leaf++;       /* continue for next L1 */
3622                 else {
3623                         /* more than 1 L1 ? */
3624                         if (k > 0)
3625                                 break;  /* build L2 page */
3626                         else {
3627                                 /* summarize in global bmap page */
3628                                 bmp->db_maxfreebud = *l2leaf;
3629                                 release_metapage(l2mp);
3630                                 goto finalize;
3631                         }
3632                 }
3633         }                       /* for each L1 in a L2 */
3634 
3635         jfs_error(ipbmap->i_sb, "function has not returned as expected\n");
3636 errout:
3637         if (l0mp)
3638                 release_metapage(l0mp);
3639         if (l1mp)
3640                 release_metapage(l1mp);
3641         release_metapage(l2mp);
3642         return -EIO;
3643 
3644         /*
3645          *      finalize bmap control page
3646          */
3647 finalize:
3648 
3649         return 0;
3650 }
3651 
3652 
3653 /*
3654  *      dbFinalizeBmap()
3655  */
3656 void dbFinalizeBmap(struct inode *ipbmap)
3657 {
3658         struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
3659         int actags, inactags, l2nl;
3660         s64 ag_rem, actfree, inactfree, avgfree;
3661         int i, n;
3662 
3663         /*
3664          *      finalize bmap control page
3665          */
3666 //finalize:
3667         /*
3668          * compute db_agpref: preferred ag to allocate from
3669          * (the leftmost ag with average free space in it);
3670          */
3671 //agpref:
3672         /* get the number of active ags and inacitve ags */
3673         actags = bmp->db_maxag + 1;
3674         inactags = bmp->db_numag - actags;
3675         ag_rem = bmp->db_mapsize & (bmp->db_agsize - 1);        /* ??? */
3676 
3677         /* determine how many blocks are in the inactive allocation
3678          * groups. in doing this, we must account for the fact that
3679          * the rightmost group might be a partial group (i.e. file
3680          * system size is not a multiple of the group size).
3681          */
3682         inactfree = (inactags && ag_rem) ?
3683             ((inactags - 1) << bmp->db_agl2size) + ag_rem
3684             : inactags << bmp->db_agl2size;
3685 
3686         /* determine how many free blocks are in the active
3687          * allocation groups plus the average number of free blocks
3688          * within the active ags.
3689          */
3690         actfree = bmp->db_nfree - inactfree;
3691         avgfree = (u32) actfree / (u32) actags;
3692 
3693         /* if the preferred allocation group has not average free space.
3694          * re-establish the preferred group as the leftmost
3695          * group with average free space.
3696          */
3697         if (bmp->db_agfree[bmp->db_agpref] < avgfree) {
3698                 for (bmp->db_agpref = 0; bmp->db_agpref < actags;
3699                      bmp->db_agpref++) {
3700                         if (bmp->db_agfree[bmp->db_agpref] >= avgfree)
3701                                 break;
3702                 }
3703                 if (bmp->db_agpref >= bmp->db_numag) {
3704                         jfs_error(ipbmap->i_sb,
3705                                   "cannot find ag with average freespace\n");
3706                 }
3707         }
3708 
3709         /*
3710          * compute db_aglevel, db_agheight, db_width, db_agstart:
3711          * an ag is covered in aglevel dmapctl summary tree,
3712          * at agheight level height (from leaf) with agwidth number of nodes
3713          * each, which starts at agstart index node of the smmary tree node
3714          * array;
3715          */
3716         bmp->db_aglevel = BMAPSZTOLEV(bmp->db_agsize);
3717         l2nl =
3718             bmp->db_agl2size - (L2BPERDMAP + bmp->db_aglevel * L2LPERCTL);
3719         bmp->db_agheight = l2nl >> 1;
3720         bmp->db_agwidth = 1 << (l2nl - (bmp->db_agheight << 1));
3721         for (i = 5 - bmp->db_agheight, bmp->db_agstart = 0, n = 1; i > 0;
3722              i--) {
3723                 bmp->db_agstart += n;
3724                 n <<= 2;
3725         }
3726 
3727 }
3728 
3729 
3730 /*
3731  * NAME:        dbInitDmap()/ujfs_idmap_page()
3732  *
3733  * FUNCTION:    initialize working/persistent bitmap of the dmap page
3734  *              for the specified number of blocks:
3735  *
3736  *              at entry, the bitmaps had been initialized as free (ZEROS);
3737  *              The number of blocks will only account for the actually
3738  *              existing blocks. Blocks which don't actually exist in
3739  *              the aggregate will be marked as allocated (ONES);
3740  *
3741  * PARAMETERS:
3742  *      dp      - pointer to page of map
3743  *      nblocks - number of blocks this page
3744  *
3745  * RETURNS: NONE
3746  */
3747 static int dbInitDmap(struct dmap * dp, s64 Blkno, int nblocks)
3748 {
3749         int blkno, w, b, r, nw, nb, i;
3750 
3751         /* starting block number within the dmap */
3752         blkno = Blkno & (BPERDMAP - 1);
3753 
3754         if (blkno == 0) {
3755                 dp->nblocks = dp->nfree = cpu_to_le32(nblocks);
3756                 dp->start = cpu_to_le64(Blkno);
3757 
3758                 if (nblocks == BPERDMAP) {
3759                         memset(&dp->wmap[0], 0, LPERDMAP * 4);
3760                         memset(&dp->pmap[0], 0, LPERDMAP * 4);
3761                         goto initTree;
3762                 }
3763         } else {
3764                 le32_add_cpu(&dp->nblocks, nblocks);
3765                 le32_add_cpu(&dp->nfree, nblocks);
3766         }
3767 
3768         /* word number containing start block number */
3769         w = blkno >> L2DBWORD;
3770 
3771         /*
3772          * free the bits corresponding to the block range (ZEROS):
3773          * note: not all bits of the first and last words may be contained
3774          * within the block range.
3775          */
3776         for (r = nblocks; r > 0; r -= nb, blkno += nb) {
3777                 /* number of bits preceding range to be freed in the word */
3778                 b = blkno & (DBWORD - 1);
3779                 /* number of bits to free in the word */
3780                 nb = min(r, DBWORD - b);
3781 
3782                 /* is partial word to be freed ? */
3783                 if (nb < DBWORD) {
3784                         /* free (set to 0) from the bitmap word */
3785                         dp->wmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3786                                                      >> b));
3787                         dp->pmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3788                                                      >> b));
3789 
3790                         /* skip the word freed */
3791                         w++;
3792                 } else {
3793                         /* free (set to 0) contiguous bitmap words */
3794                         nw = r >> L2DBWORD;
3795                         memset(&dp->wmap[w], 0, nw * 4);
3796                         memset(&dp->pmap[w], 0, nw * 4);
3797 
3798                         /* skip the words freed */
3799                         nb = nw << L2DBWORD;
3800                         w += nw;
3801                 }
3802         }
3803 
3804         /*
3805          * mark bits following the range to be freed (non-existing
3806          * blocks) as allocated (ONES)
3807          */
3808 
3809         if (blkno == BPERDMAP)
3810                 goto initTree;
3811 
3812         /* the first word beyond the end of existing blocks */
3813         w = blkno >> L2DBWORD;
3814 
3815         /* does nblocks fall on a 32-bit boundary ? */
3816         b = blkno & (DBWORD - 1);
3817         if (b) {
3818                 /* mark a partial word allocated */
3819                 dp->wmap[w] = dp->pmap[w] = cpu_to_le32(ONES >> b);
3820                 w++;
3821         }
3822 
3823         /* set the rest of the words in the page to allocated (ONES) */
3824         for (i = w; i < LPERDMAP; i++)
3825                 dp->pmap[i] = dp->wmap[i] = cpu_to_le32(ONES);
3826 
3827         /*
3828          * init tree
3829          */
3830       initTree:
3831         return (dbInitDmapTree(dp));
3832 }
3833 
3834 
3835 /*
3836  * NAME:        dbInitDmapTree()/ujfs_complete_dmap()
3837  *
3838  * FUNCTION:    initialize summary tree of the specified dmap:
3839  *
3840  *              at entry, bitmap of the dmap has been initialized;
3841  *
3842  * PARAMETERS:
3843  *      dp      - dmap to complete
3844  *      blkno   - starting block number for this dmap
3845  *      treemax - will be filled in with max free for this dmap
3846  *
3847  * RETURNS:     max free string at the root of the tree
3848  */
3849 static int dbInitDmapTree(struct dmap * dp)
3850 {
3851         struct dmaptree *tp;
3852         s8 *cp;
3853         int i;
3854 
3855         /* init fixed info of tree */
3856         tp = &dp->tree;
3857         tp->nleafs = cpu_to_le32(LPERDMAP);
3858         tp->l2nleafs = cpu_to_le32(L2LPERDMAP);
3859         tp->leafidx = cpu_to_le32(LEAFIND);
3860         tp->height = cpu_to_le32(4);
3861         tp->budmin = BUDMIN;
3862 
3863         /* init each leaf from corresponding wmap word:
3864          * note: leaf is set to NOFREE(-1) if all blocks of corresponding
3865          * bitmap word are allocated.
3866          */
3867         cp = tp->stree + le32_to_cpu(tp->leafidx);
3868         for (i = 0; i < LPERDMAP; i++)
3869                 *cp++ = dbMaxBud((u8 *) & dp->wmap[i]);
3870 
3871         /* build the dmap's binary buddy summary tree */
3872         return (dbInitTree(tp));
3873 }
3874 
3875 
3876 /*
3877  * NAME:        dbInitTree()/ujfs_adjtree()
3878  *
3879  * FUNCTION:    initialize binary buddy summary tree of a dmap or dmapctl.
3880  *
3881  *              at entry, the leaves of the tree has been initialized
3882  *              from corresponding bitmap word or root of summary tree
3883  *              of the child control page;
3884  *              configure binary buddy system at the leaf level, then
3885  *              bubble up the values of the leaf nodes up the tree.
3886  *
3887  * PARAMETERS:
3888  *      cp      - Pointer to the root of the tree
3889  *      l2leaves- Number of leaf nodes as a power of 2
3890  *      l2min   - Number of blocks that can be covered by a leaf
3891  *                as a power of 2
3892  *
3893  * RETURNS: max free string at the root of the tree
3894  */
3895 static int dbInitTree(struct dmaptree * dtp)
3896 {
3897         int l2max, l2free, bsize, nextb, i;
3898         int child, parent, nparent;
3899         s8 *tp, *cp, *cp1;
3900 
3901         tp = dtp->stree;
3902 
3903         /* Determine the maximum free string possible for the leaves */
3904         l2max = le32_to_cpu(dtp->l2nleafs) + dtp->budmin;
3905 
3906         /*
3907          * configure the leaf levevl into binary buddy system
3908          *
3909          * Try to combine buddies starting with a buddy size of 1
3910          * (i.e. two leaves). At a buddy size of 1 two buddy leaves
3911          * can be combined if both buddies have a maximum free of l2min;
3912          * the combination will result in the left-most buddy leaf having
3913          * a maximum free of l2min+1.
3914          * After processing all buddies for a given size, process buddies
3915          * at the next higher buddy size (i.e. current size * 2) and
3916          * the next maximum free (current free + 1).
3917          * This continues until the maximum possible buddy combination
3918          * yields maximum free.
3919          */
3920         for (l2free = dtp->budmin, bsize = 1; l2free < l2max;
3921              l2free++, bsize = nextb) {
3922                 /* get next buddy size == current buddy pair size */
3923                 nextb = bsize << 1;
3924 
3925                 /* scan each adjacent buddy pair at current buddy size */
3926                 for (i = 0, cp = tp + le32_to_cpu(dtp->leafidx);
3927                      i < le32_to_cpu(dtp->nleafs);
3928                      i += nextb, cp += nextb) {
3929                         /* coalesce if both adjacent buddies are max free */
3930                         if (*cp == l2free && *(cp + bsize) == l2free) {
3931                                 *cp = l2free + 1;       /* left take right */
3932                                 *(cp + bsize) = -1;     /* right give left */
3933                         }
3934                 }
3935         }
3936 
3937         /*
3938          * bubble summary information of leaves up the tree.
3939          *
3940          * Starting at the leaf node level, the four nodes described by
3941          * the higher level parent node are compared for a maximum free and
3942          * this maximum becomes the value of the parent node.
3943          * when all lower level nodes are processed in this fashion then
3944          * move up to the next level (parent becomes a lower level node) and
3945          * continue the process for that level.
3946          */
3947         for (child = le32_to_cpu(dtp->leafidx),
3948              nparent = le32_to_cpu(dtp->nleafs) >> 2;
3949              nparent > 0; nparent >>= 2, child = parent) {
3950                 /* get index of 1st node of parent level */
3951                 parent = (child - 1) >> 2;
3952 
3953                 /* set the value of the parent node as the maximum
3954                  * of the four nodes of the current level.
3955                  */
3956                 for (i = 0, cp = tp + child, cp1 = tp + parent;
3957                      i < nparent; i++, cp += 4, cp1++)
3958                         *cp1 = TREEMAX(cp);
3959         }
3960 
3961         return (*tp);
3962 }
3963 
3964 
3965 /*
3966  *      dbInitDmapCtl()
3967  *
3968  * function: initialize dmapctl page
3969  */
3970 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i)
3971 {                               /* start leaf index not covered by range */
3972         s8 *cp;
3973 
3974         dcp->nleafs = cpu_to_le32(LPERCTL);
3975         dcp->l2nleafs = cpu_to_le32(L2LPERCTL);
3976         dcp->leafidx = cpu_to_le32(CTLLEAFIND);
3977         dcp->height = cpu_to_le32(5);
3978         dcp->budmin = L2BPERDMAP + L2LPERCTL * level;
3979 
3980         /*
3981          * initialize the leaves of current level that were not covered
3982          * by the specified input block range (i.e. the leaves have no
3983          * low level dmapctl or dmap).
3984          */
3985         cp = &dcp->stree[CTLLEAFIND + i];
3986         for (; i < LPERCTL; i++)
3987                 *cp++ = NOFREE;
3988 
3989         /* build the dmap's binary buddy summary tree */
3990         return (dbInitTree((struct dmaptree *) dcp));
3991 }
3992 
3993 
3994 /*
3995  * NAME:        dbGetL2AGSize()/ujfs_getagl2size()
3996  *
3997  * FUNCTION:    Determine log2(allocation group size) from aggregate size
3998  *
3999  * PARAMETERS:
4000  *      nblocks - Number of blocks in aggregate
4001  *
4002  * RETURNS: log2(allocation group size) in aggregate blocks
4003  */
4004 static int dbGetL2AGSize(s64 nblocks)
4005 {
4006         s64 sz;
4007         s64 m;
4008         int l2sz;
4009 
4010         if (nblocks < BPERDMAP * MAXAG)
4011                 return (L2BPERDMAP);
4012 
4013         /* round up aggregate size to power of 2 */
4014         m = ((u64) 1 << (64 - 1));
4015         for (l2sz = 64; l2sz >= 0; l2sz--, m >>= 1) {
4016                 if (m & nblocks)
4017                         break;
4018         }
4019 
4020         sz = (s64) 1 << l2sz;
4021         if (sz < nblocks)
4022                 l2sz += 1;
4023 
4024         /* agsize = roundupSize/max_number_of_ag */
4025         return (l2sz - L2MAXAG);
4026 }
4027 
4028 
4029 /*
4030  * NAME:        dbMapFileSizeToMapSize()
4031  *
4032  * FUNCTION:    compute number of blocks the block allocation map file
4033  *              can cover from the map file size;
4034  *
4035  * RETURNS:     Number of blocks which can be covered by this block map file;
4036  */
4037 
4038 /*
4039  * maximum number of map pages at each level including control pages
4040  */
4041 #define MAXL0PAGES      (1 + LPERCTL)
4042 #define MAXL1PAGES      (1 + LPERCTL * MAXL0PAGES)
4043 #define MAXL2PAGES      (1 + LPERCTL * MAXL1PAGES)
4044 
4045 /*
4046  * convert number of map pages to the zero origin top dmapctl level
4047  */
4048 #define BMAPPGTOLEV(npages)     \
4049         (((npages) <= 3 + MAXL0PAGES) ? 0 : \
4050          ((npages) <= 2 + MAXL1PAGES) ? 1 : 2)
4051 
4052 s64 dbMapFileSizeToMapSize(struct inode * ipbmap)
4053 {
4054         struct super_block *sb = ipbmap->i_sb;
4055         s64 nblocks;
4056         s64 npages, ndmaps;
4057         int level, i;
4058         int complete, factor;
4059 
4060         nblocks = ipbmap->i_size >> JFS_SBI(sb)->l2bsize;
4061         npages = nblocks >> JFS_SBI(sb)->l2nbperpage;
4062         level = BMAPPGTOLEV(npages);
4063 
4064         /* At each level, accumulate the number of dmap pages covered by
4065          * the number of full child levels below it;
4066          * repeat for the last incomplete child level.
4067          */
4068         ndmaps = 0;
4069         npages--;               /* skip the first global control page */
4070         /* skip higher level control pages above top level covered by map */
4071         npages -= (2 - level);
4072         npages--;               /* skip top level's control page */
4073         for (i = level; i >= 0; i--) {
4074                 factor =
4075                     (i == 2) ? MAXL1PAGES : ((i == 1) ? MAXL0PAGES : 1);
4076                 complete = (u32) npages / factor;
4077                 ndmaps += complete * ((i == 2) ? LPERCTL * LPERCTL :
4078                                       ((i == 1) ? LPERCTL : 1));
4079 
4080                 /* pages in last/incomplete child */
4081                 npages = (u32) npages % factor;
4082                 /* skip incomplete child's level control page */
4083                 npages--;
4084         }
4085 
4086         /* convert the number of dmaps into the number of blocks
4087          * which can be covered by the dmaps;
4088          */
4089         nblocks = ndmaps << L2BPERDMAP;
4090 
4091         return (nblocks);
4092 }
4093 

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