1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) International Business Machines Corp., 2000-2004
4 * Portions Copyright (C) Tino Reichardt, 2012
5 */
6
7 #include <linux/fs.h>
8 #include <linux/slab.h>
9 #include "jfs_incore.h"
10 #include "jfs_superblock.h"
11 #include "jfs_dmap.h"
12 #include "jfs_imap.h"
13 #include "jfs_lock.h"
14 #include "jfs_metapage.h"
15 #include "jfs_debug.h"
16 #include "jfs_discard.h"
17
18 /*
19 * SERIALIZATION of the Block Allocation Map.
20 *
21 * the working state of the block allocation map is accessed in
22 * two directions:
23 *
24 * 1) allocation and free requests that start at the dmap
25 * level and move up through the dmap control pages (i.e.
26 * the vast majority of requests).
27 *
28 * 2) allocation requests that start at dmap control page
29 * level and work down towards the dmaps.
30 *
31 * the serialization scheme used here is as follows.
32 *
33 * requests which start at the bottom are serialized against each
34 * other through buffers and each requests holds onto its buffers
35 * as it works it way up from a single dmap to the required level
36 * of dmap control page.
37 * requests that start at the top are serialized against each other
38 * and request that start from the bottom by the multiple read/single
39 * write inode lock of the bmap inode. requests starting at the top
40 * take this lock in write mode while request starting at the bottom
41 * take the lock in read mode. a single top-down request may proceed
42 * exclusively while multiple bottoms-up requests may proceed
43 * simultaneously (under the protection of busy buffers).
44 *
45 * in addition to information found in dmaps and dmap control pages,
46 * the working state of the block allocation map also includes read/
47 * write information maintained in the bmap descriptor (i.e. total
48 * free block count, allocation group level free block counts).
49 * a single exclusive lock (BMAP_LOCK) is used to guard this information
50 * in the face of multiple-bottoms up requests.
51 * (lock ordering: IREAD_LOCK, BMAP_LOCK);
52 *
53 * accesses to the persistent state of the block allocation map (limited
54 * to the persistent bitmaps in dmaps) is guarded by (busy) buffers.
55 */
56
57 #define BMAP_LOCK_INIT(bmp) mutex_init(&bmp->db_bmaplock)
58 #define BMAP_LOCK(bmp) mutex_lock(&bmp->db_bmaplock)
59 #define BMAP_UNLOCK(bmp) mutex_unlock(&bmp->db_bmaplock)
60
61 /*
62 * forward references
63 */
64 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
65 int nblocks);
66 static void dbSplit(dmtree_t *tp, int leafno, int splitsz, int newval, bool is_ctl);
67 static int dbBackSplit(dmtree_t *tp, int leafno, bool is_ctl);
68 static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl);
69 static void dbAdjTree(dmtree_t *tp, int leafno, int newval, bool is_ctl);
70 static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
71 int level);
72 static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results);
73 static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
74 int nblocks);
75 static int dbAllocNear(struct bmap * bmp, struct dmap * dp, s64 blkno,
76 int nblocks,
77 int l2nb, s64 * results);
78 static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
79 int nblocks);
80 static int dbAllocDmapLev(struct bmap * bmp, struct dmap * dp, int nblocks,
81 int l2nb,
82 s64 * results);
83 static int dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb,
84 s64 * results);
85 static int dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno,
86 s64 * results);
87 static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks);
88 static int dbFindBits(u32 word, int l2nb);
89 static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno);
90 static int dbFindLeaf(dmtree_t *tp, int l2nb, int *leafidx, bool is_ctl);
91 static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
92 int nblocks);
93 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
94 int nblocks);
95 static int dbMaxBud(u8 * cp);
96 static int blkstol2(s64 nb);
97
98 static int cntlz(u32 value);
99 static int cnttz(u32 word);
100
101 static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
102 int nblocks);
103 static int dbInitDmap(struct dmap * dp, s64 blkno, int nblocks);
104 static int dbInitDmapTree(struct dmap * dp);
105 static int dbInitTree(struct dmaptree * dtp);
106 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i);
107 static int dbGetL2AGSize(s64 nblocks);
108
109 /*
110 * buddy table
111 *
112 * table used for determining buddy sizes within characters of
113 * dmap bitmap words. the characters themselves serve as indexes
114 * into the table, with the table elements yielding the maximum
115 * binary buddy of free bits within the character.
116 */
117 static const s8 budtab[256] = {
118 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
119 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
120 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
121 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
122 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
123 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
124 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
125 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
126 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
127 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
128 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
129 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
130 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
131 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
132 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0,
133 2, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, -1
134 };
135
136 /*
137 * NAME: dbMount()
138 *
139 * FUNCTION: initializate the block allocation map.
140 *
141 * memory is allocated for the in-core bmap descriptor and
142 * the in-core descriptor is initialized from disk.
143 *
144 * PARAMETERS:
145 * ipbmap - pointer to in-core inode for the block map.
146 *
147 * RETURN VALUES:
148 * 0 - success
149 * -ENOMEM - insufficient memory
150 * -EIO - i/o error
151 * -EINVAL - wrong bmap data
152 */
153 int dbMount(struct inode *ipbmap)
154 {
155 struct bmap *bmp;
156 struct dbmap_disk *dbmp_le;
157 struct metapage *mp;
158 int i, err;
159
160 /*
161 * allocate/initialize the in-memory bmap descriptor
162 */
163 /* allocate memory for the in-memory bmap descriptor */
164 bmp = kmalloc(sizeof(struct bmap), GFP_KERNEL);
165 if (bmp == NULL)
166 return -ENOMEM;
167
168 /* read the on-disk bmap descriptor. */
169 mp = read_metapage(ipbmap,
170 BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
171 PSIZE, 0);
172 if (mp == NULL) {
173 err = -EIO;
174 goto err_kfree_bmp;
175 }
176
177 /* copy the on-disk bmap descriptor to its in-memory version. */
178 dbmp_le = (struct dbmap_disk *) mp->data;
179 bmp->db_mapsize = le64_to_cpu(dbmp_le->dn_mapsize);
180 bmp->db_nfree = le64_to_cpu(dbmp_le->dn_nfree);
181
182 bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage);
183 if (bmp->db_l2nbperpage > L2PSIZE - L2MINBLOCKSIZE ||
184 bmp->db_l2nbperpage < 0) {
185 err = -EINVAL;
186 goto err_release_metapage;
187 }
188
189 bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag);
190 if (!bmp->db_numag || bmp->db_numag >= MAXAG) {
191 err = -EINVAL;
192 goto err_release_metapage;
193 }
194
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 if (bmp->db_maxag >= MAXAG || bmp->db_maxag < 0 ||
199 bmp->db_agpref >= MAXAG || bmp->db_agpref < 0) {
200 err = -EINVAL;
201 goto err_release_metapage;
202 }
203
204 bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
205 bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
206 bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
207 bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
208 bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
209 if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG ||
210 bmp->db_agl2size < 0) {
211 err = -EINVAL;
212 goto err_release_metapage;
213 }
214
215 if (((bmp->db_mapsize - 1) >> bmp->db_agl2size) > MAXAG) {
216 err = -EINVAL;
217 goto err_release_metapage;
218 }
219
220 for (i = 0; i < MAXAG; i++)
221 bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]);
222 bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize);
223 bmp->db_maxfreebud = dbmp_le->dn_maxfreebud;
224
225 /* release the buffer. */
226 release_metapage(mp);
227
228 /* bind the bmap inode and the bmap descriptor to each other. */
229 bmp->db_ipbmap = ipbmap;
230 JFS_SBI(ipbmap->i_sb)->bmap = bmp;
231
232 memset(bmp->db_active, 0, sizeof(bmp->db_active));
233
234 /*
235 * allocate/initialize the bmap lock
236 */
237 BMAP_LOCK_INIT(bmp);
238
239 return (0);
240
241 err_release_metapage:
242 release_metapage(mp);
243 err_kfree_bmp:
244 kfree(bmp);
245 return err;
246 }
247
248
249 /*
250 * NAME: dbUnmount()
251 *
252 * FUNCTION: terminate the block allocation map in preparation for
253 * file system unmount.
254 *
255 * the in-core bmap descriptor is written to disk and
256 * the memory for this descriptor is freed.
257 *
258 * PARAMETERS:
259 * ipbmap - pointer to in-core inode for the block map.
260 *
261 * RETURN VALUES:
262 * 0 - success
263 * -EIO - i/o error
264 */
265 int dbUnmount(struct inode *ipbmap, int mounterror)
266 {
267 struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
268
269 if (!(mounterror || isReadOnly(ipbmap)))
270 dbSync(ipbmap);
271
272 /*
273 * Invalidate the page cache buffers
274 */
275 truncate_inode_pages(ipbmap->i_mapping, 0);
276
277 /* free the memory for the in-memory bmap. */
278 kfree(bmp);
279 JFS_SBI(ipbmap->i_sb)->bmap = NULL;
280
281 return (0);
282 }
283
284 /*
285 * dbSync()
286 */
287 int dbSync(struct inode *ipbmap)
288 {
289 struct dbmap_disk *dbmp_le;
290 struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
291 struct metapage *mp;
292 int i;
293
294 /*
295 * write bmap global control page
296 */
297 /* get the buffer for the on-disk bmap descriptor. */
298 mp = read_metapage(ipbmap,
299 BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
300 PSIZE, 0);
301 if (mp == NULL) {
302 jfs_err("dbSync: read_metapage failed!");
303 return -EIO;
304 }
305 /* copy the in-memory version of the bmap to the on-disk version */
306 dbmp_le = (struct dbmap_disk *) mp->data;
307 dbmp_le->dn_mapsize = cpu_to_le64(bmp->db_mapsize);
308 dbmp_le->dn_nfree = cpu_to_le64(bmp->db_nfree);
309 dbmp_le->dn_l2nbperpage = cpu_to_le32(bmp->db_l2nbperpage);
310 dbmp_le->dn_numag = cpu_to_le32(bmp->db_numag);
311 dbmp_le->dn_maxlevel = cpu_to_le32(bmp->db_maxlevel);
312 dbmp_le->dn_maxag = cpu_to_le32(bmp->db_maxag);
313 dbmp_le->dn_agpref = cpu_to_le32(bmp->db_agpref);
314 dbmp_le->dn_aglevel = cpu_to_le32(bmp->db_aglevel);
315 dbmp_le->dn_agheight = cpu_to_le32(bmp->db_agheight);
316 dbmp_le->dn_agwidth = cpu_to_le32(bmp->db_agwidth);
317 dbmp_le->dn_agstart = cpu_to_le32(bmp->db_agstart);
318 dbmp_le->dn_agl2size = cpu_to_le32(bmp->db_agl2size);
319 for (i = 0; i < MAXAG; i++)
320 dbmp_le->dn_agfree[i] = cpu_to_le64(bmp->db_agfree[i]);
321 dbmp_le->dn_agsize = cpu_to_le64(bmp->db_agsize);
322 dbmp_le->dn_maxfreebud = bmp->db_maxfreebud;
323
324 /* write the buffer */
325 write_metapage(mp);
326
327 /*
328 * write out dirty pages of bmap
329 */
330 filemap_write_and_wait(ipbmap->i_mapping);
331
332 diWriteSpecial(ipbmap, 0);
333
334 return (0);
335 }
336
337 /*
338 * NAME: dbFree()
339 *
340 * FUNCTION: free the specified block range from the working block
341 * allocation map.
342 *
343 * the blocks will be free from the working map one dmap
344 * at a time.
345 *
346 * PARAMETERS:
347 * ip - pointer to in-core inode;
348 * blkno - starting block number to be freed.
349 * nblocks - number of blocks to be freed.
350 *
351 * RETURN VALUES:
352 * 0 - success
353 * -EIO - i/o error
354 */
355 int dbFree(struct inode *ip, s64 blkno, s64 nblocks)
356 {
357 struct metapage *mp;
358 struct dmap *dp;
359 int nb, rc;
360 s64 lblkno, rem;
361 struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
362 struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
363 struct super_block *sb = ipbmap->i_sb;
364
365 IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
366
367 /* block to be freed better be within the mapsize. */
368 if (unlikely((blkno == 0) || (blkno + nblocks > bmp->db_mapsize))) {
369 IREAD_UNLOCK(ipbmap);
370 printk(KERN_ERR "blkno = %Lx, nblocks = %Lx\n",
371 (unsigned long long) blkno,
372 (unsigned long long) nblocks);
373 jfs_error(ip->i_sb, "block to be freed is outside the map\n");
374 return -EIO;
375 }
376
377 /**
378 * TRIM the blocks, when mounted with discard option
379 */
380 if (JFS_SBI(sb)->flag & JFS_DISCARD)
381 if (JFS_SBI(sb)->minblks_trim <= nblocks)
382 jfs_issue_discard(ipbmap, blkno, nblocks);
383
384 /*
385 * free the blocks a dmap at a time.
386 */
387 mp = NULL;
388 for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
389 /* release previous dmap if any */
390 if (mp) {
391 write_metapage(mp);
392 }
393
394 /* get the buffer for the current dmap. */
395 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
396 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
397 if (mp == NULL) {
398 IREAD_UNLOCK(ipbmap);
399 return -EIO;
400 }
401 dp = (struct dmap *) mp->data;
402
403 /* determine the number of blocks to be freed from
404 * this dmap.
405 */
406 nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
407
408 /* free the blocks. */
409 if ((rc = dbFreeDmap(bmp, dp, blkno, nb))) {
410 jfs_error(ip->i_sb, "error in block map\n");
411 release_metapage(mp);
412 IREAD_UNLOCK(ipbmap);
413 return (rc);
414 }
415 }
416
417 /* write the last buffer. */
418 if (mp)
419 write_metapage(mp);
420
421 IREAD_UNLOCK(ipbmap);
422
423 return (0);
424 }
425
426
427 /*
428 * NAME: dbUpdatePMap()
429 *
430 * FUNCTION: update the allocation state (free or allocate) of the
431 * specified block range in the persistent block allocation map.
432 *
433 * the blocks will be updated in the persistent map one
434 * dmap at a time.
435 *
436 * PARAMETERS:
437 * ipbmap - pointer to in-core inode for the block map.
438 * free - 'true' if block range is to be freed from the persistent
439 * map; 'false' if it is to be allocated.
440 * blkno - starting block number of the range.
441 * nblocks - number of contiguous blocks in the range.
442 * tblk - transaction block;
443 *
444 * RETURN VALUES:
445 * 0 - success
446 * -EIO - i/o error
447 */
448 int
449 dbUpdatePMap(struct inode *ipbmap,
450 int free, s64 blkno, s64 nblocks, struct tblock * tblk)
451 {
452 int nblks, dbitno, wbitno, rbits;
453 int word, nbits, nwords;
454 struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
455 s64 lblkno, rem, lastlblkno;
456 u32 mask;
457 struct dmap *dp;
458 struct metapage *mp;
459 struct jfs_log *log;
460 int lsn, difft, diffp;
461 unsigned long flags;
462
463 /* the blocks better be within the mapsize. */
464 if (blkno + nblocks > bmp->db_mapsize) {
465 printk(KERN_ERR "blkno = %Lx, nblocks = %Lx\n",
466 (unsigned long long) blkno,
467 (unsigned long long) nblocks);
468 jfs_error(ipbmap->i_sb, "blocks are outside the map\n");
469 return -EIO;
470 }
471
472 /* compute delta of transaction lsn from log syncpt */
473 lsn = tblk->lsn;
474 log = (struct jfs_log *) JFS_SBI(tblk->sb)->log;
475 logdiff(difft, lsn, log);
476
477 /*
478 * update the block state a dmap at a time.
479 */
480 mp = NULL;
481 lastlblkno = 0;
482 for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
483 /* get the buffer for the current dmap. */
484 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
485 if (lblkno != lastlblkno) {
486 if (mp) {
487 write_metapage(mp);
488 }
489
490 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE,
491 0);
492 if (mp == NULL)
493 return -EIO;
494 metapage_wait_for_io(mp);
495 }
496 dp = (struct dmap *) mp->data;
497
498 /* determine the bit number and word within the dmap of
499 * the starting block. also determine how many blocks
500 * are to be updated within this dmap.
501 */
502 dbitno = blkno & (BPERDMAP - 1);
503 word = dbitno >> L2DBWORD;
504 nblks = min(rem, (s64)BPERDMAP - dbitno);
505
506 /* update the bits of the dmap words. the first and last
507 * words may only have a subset of their bits updated. if
508 * this is the case, we'll work against that word (i.e.
509 * partial first and/or last) only in a single pass. a
510 * single pass will also be used to update all words that
511 * are to have all their bits updated.
512 */
513 for (rbits = nblks; rbits > 0;
514 rbits -= nbits, dbitno += nbits) {
515 /* determine the bit number within the word and
516 * the number of bits within the word.
517 */
518 wbitno = dbitno & (DBWORD - 1);
519 nbits = min(rbits, DBWORD - wbitno);
520
521 /* check if only part of the word is to be updated. */
522 if (nbits < DBWORD) {
523 /* update (free or allocate) the bits
524 * in this word.
525 */
526 mask =
527 (ONES << (DBWORD - nbits) >> wbitno);
528 if (free)
529 dp->pmap[word] &=
530 cpu_to_le32(~mask);
531 else
532 dp->pmap[word] |=
533 cpu_to_le32(mask);
534
535 word += 1;
536 } else {
537 /* one or more words are to have all
538 * their bits updated. determine how
539 * many words and how many bits.
540 */
541 nwords = rbits >> L2DBWORD;
542 nbits = nwords << L2DBWORD;
543
544 /* update (free or allocate) the bits
545 * in these words.
546 */
547 if (free)
548 memset(&dp->pmap[word], 0,
549 nwords * 4);
550 else
551 memset(&dp->pmap[word], (int) ONES,
552 nwords * 4);
553
554 word += nwords;
555 }
556 }
557
558 /*
559 * update dmap lsn
560 */
561 if (lblkno == lastlblkno)
562 continue;
563
564 lastlblkno = lblkno;
565
566 LOGSYNC_LOCK(log, flags);
567 if (mp->lsn != 0) {
568 /* inherit older/smaller lsn */
569 logdiff(diffp, mp->lsn, log);
570 if (difft < diffp) {
571 mp->lsn = lsn;
572
573 /* move bp after tblock in logsync list */
574 list_move(&mp->synclist, &tblk->synclist);
575 }
576
577 /* inherit younger/larger clsn */
578 logdiff(difft, tblk->clsn, log);
579 logdiff(diffp, mp->clsn, log);
580 if (difft > diffp)
581 mp->clsn = tblk->clsn;
582 } else {
583 mp->log = log;
584 mp->lsn = lsn;
585
586 /* insert bp after tblock in logsync list */
587 log->count++;
588 list_add(&mp->synclist, &tblk->synclist);
589
590 mp->clsn = tblk->clsn;
591 }
592 LOGSYNC_UNLOCK(log, flags);
593 }
594
595 /* write the last buffer. */
596 if (mp) {
597 write_metapage(mp);
598 }
599
600 return (0);
601 }
602
603
604 /*
605 * NAME: dbNextAG()
606 *
607 * FUNCTION: find the preferred allocation group for new allocations.
608 *
609 * Within the allocation groups, we maintain a preferred
610 * allocation group which consists of a group with at least
611 * average free space. It is the preferred group that we target
612 * new inode allocation towards. The tie-in between inode
613 * allocation and block allocation occurs as we allocate the
614 * first (data) block of an inode and specify the inode (block)
615 * as the allocation hint for this block.
616 *
617 * We try to avoid having more than one open file growing in
618 * an allocation group, as this will lead to fragmentation.
619 * This differs from the old OS/2 method of trying to keep
620 * empty ags around for large allocations.
621 *
622 * PARAMETERS:
623 * ipbmap - pointer to in-core inode for the block map.
624 *
625 * RETURN VALUES:
626 * the preferred allocation group number.
627 */
628 int dbNextAG(struct inode *ipbmap)
629 {
630 s64 avgfree;
631 int agpref;
632 s64 hwm = 0;
633 int i;
634 int next_best = -1;
635 struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
636
637 BMAP_LOCK(bmp);
638
639 /* determine the average number of free blocks within the ags. */
640 avgfree = (u32)bmp->db_nfree / bmp->db_numag;
641
642 /*
643 * if the current preferred ag does not have an active allocator
644 * and has at least average freespace, return it
645 */
646 agpref = bmp->db_agpref;
647 if ((atomic_read(&bmp->db_active[agpref]) == 0) &&
648 (bmp->db_agfree[agpref] >= avgfree))
649 goto unlock;
650
651 /* From the last preferred ag, find the next one with at least
652 * average free space.
653 */
654 for (i = 0 ; i < bmp->db_numag; i++, agpref++) {
655 if (agpref >= bmp->db_numag)
656 agpref = 0;
657
658 if (atomic_read(&bmp->db_active[agpref]))
659 /* open file is currently growing in this ag */
660 continue;
661 if (bmp->db_agfree[agpref] >= avgfree) {
662 /* Return this one */
663 bmp->db_agpref = agpref;
664 goto unlock;
665 } else if (bmp->db_agfree[agpref] > hwm) {
666 /* Less than avg. freespace, but best so far */
667 hwm = bmp->db_agfree[agpref];
668 next_best = agpref;
669 }
670 }
671
672 /*
673 * If no inactive ag was found with average freespace, use the
674 * next best
675 */
676 if (next_best != -1)
677 bmp->db_agpref = next_best;
678 /* else leave db_agpref unchanged */
679 unlock:
680 BMAP_UNLOCK(bmp);
681
682 /* return the preferred group.
683 */
684 return (bmp->db_agpref);
685 }
686
687 /*
688 * NAME: dbAlloc()
689 *
690 * FUNCTION: attempt to allocate a specified number of contiguous free
691 * blocks from the working allocation block map.
692 *
693 * the block allocation policy uses hints and a multi-step
694 * approach.
695 *
696 * for allocation requests smaller than the number of blocks
697 * per dmap, we first try to allocate the new blocks
698 * immediately following the hint. if these blocks are not
699 * available, we try to allocate blocks near the hint. if
700 * no blocks near the hint are available, we next try to
701 * allocate within the same dmap as contains the hint.
702 *
703 * if no blocks are available in the dmap or the allocation
704 * request is larger than the dmap size, we try to allocate
705 * within the same allocation group as contains the hint. if
706 * this does not succeed, we finally try to allocate anywhere
707 * within the aggregate.
708 *
709 * we also try to allocate anywhere within the aggregate
710 * for allocation requests larger than the allocation group
711 * size or requests that specify no hint value.
712 *
713 * PARAMETERS:
714 * ip - pointer to in-core inode;
715 * hint - allocation hint.
716 * nblocks - number of contiguous blocks in the range.
717 * results - on successful return, set to the starting block number
718 * of the newly allocated contiguous range.
719 *
720 * RETURN VALUES:
721 * 0 - success
722 * -ENOSPC - insufficient disk resources
723 * -EIO - i/o error
724 */
725 int dbAlloc(struct inode *ip, s64 hint, s64 nblocks, s64 * results)
726 {
727 int rc, agno;
728 struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
729 struct bmap *bmp;
730 struct metapage *mp;
731 s64 lblkno, blkno;
732 struct dmap *dp;
733 int l2nb;
734 s64 mapSize;
735 int writers;
736
737 /* assert that nblocks is valid */
738 assert(nblocks > 0);
739
740 /* get the log2 number of blocks to be allocated.
741 * if the number of blocks is not a log2 multiple,
742 * it will be rounded up to the next log2 multiple.
743 */
744 l2nb = BLKSTOL2(nblocks);
745
746 bmp = JFS_SBI(ip->i_sb)->bmap;
747
748 mapSize = bmp->db_mapsize;
749
750 /* the hint should be within the map */
751 if (hint >= mapSize) {
752 jfs_error(ip->i_sb, "the hint is outside the map\n");
753 return -EIO;
754 }
755
756 /* if the number of blocks to be allocated is greater than the
757 * allocation group size, try to allocate anywhere.
758 */
759 if (l2nb > bmp->db_agl2size) {
760 IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
761
762 rc = dbAllocAny(bmp, nblocks, l2nb, results);
763
764 goto write_unlock;
765 }
766
767 /*
768 * If no hint, let dbNextAG recommend an allocation group
769 */
770 if (hint == 0)
771 goto pref_ag;
772
773 /* we would like to allocate close to the hint. adjust the
774 * hint to the block following the hint since the allocators
775 * will start looking for free space starting at this point.
776 */
777 blkno = hint + 1;
778
779 if (blkno >= bmp->db_mapsize)
780 goto pref_ag;
781
782 agno = blkno >> bmp->db_agl2size;
783
784 /* check if blkno crosses over into a new allocation group.
785 * if so, check if we should allow allocations within this
786 * allocation group.
787 */
788 if ((blkno & (bmp->db_agsize - 1)) == 0)
789 /* check if the AG is currently being written to.
790 * if so, call dbNextAG() to find a non-busy
791 * AG with sufficient free space.
792 */
793 if (atomic_read(&bmp->db_active[agno]))
794 goto pref_ag;
795
796 /* check if the allocation request size can be satisfied from a
797 * single dmap. if so, try to allocate from the dmap containing
798 * the hint using a tiered strategy.
799 */
800 if (nblocks <= BPERDMAP) {
801 IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
802
803 /* get the buffer for the dmap containing the hint.
804 */
805 rc = -EIO;
806 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
807 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
808 if (mp == NULL)
809 goto read_unlock;
810
811 dp = (struct dmap *) mp->data;
812
813 /* first, try to satisfy the allocation request with the
814 * blocks beginning at the hint.
815 */
816 if ((rc = dbAllocNext(bmp, dp, blkno, (int) nblocks))
817 != -ENOSPC) {
818 if (rc == 0) {
819 *results = blkno;
820 mark_metapage_dirty(mp);
821 }
822
823 release_metapage(mp);
824 goto read_unlock;
825 }
826
827 writers = atomic_read(&bmp->db_active[agno]);
828 if ((writers > 1) ||
829 ((writers == 1) && (JFS_IP(ip)->active_ag != agno))) {
830 /*
831 * Someone else is writing in this allocation
832 * group. To avoid fragmenting, try another ag
833 */
834 release_metapage(mp);
835 IREAD_UNLOCK(ipbmap);
836 goto pref_ag;
837 }
838
839 /* next, try to satisfy the allocation request with blocks
840 * near the hint.
841 */
842 if ((rc =
843 dbAllocNear(bmp, dp, blkno, (int) nblocks, l2nb, results))
844 != -ENOSPC) {
845 if (rc == 0)
846 mark_metapage_dirty(mp);
847
848 release_metapage(mp);
849 goto read_unlock;
850 }
851
852 /* try to satisfy the allocation request with blocks within
853 * the same dmap as the hint.
854 */
855 if ((rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results))
856 != -ENOSPC) {
857 if (rc == 0)
858 mark_metapage_dirty(mp);
859
860 release_metapage(mp);
861 goto read_unlock;
862 }
863
864 release_metapage(mp);
865 IREAD_UNLOCK(ipbmap);
866 }
867
868 /* try to satisfy the allocation request with blocks within
869 * the same allocation group as the hint.
870 */
871 IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
872 if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) != -ENOSPC)
873 goto write_unlock;
874
875 IWRITE_UNLOCK(ipbmap);
876
877
878 pref_ag:
879 /*
880 * Let dbNextAG recommend a preferred allocation group
881 */
882 agno = dbNextAG(ipbmap);
883 IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
884
885 /* Try to allocate within this allocation group. if that fails, try to
886 * allocate anywhere in the map.
887 */
888 if ((rc = dbAllocAG(bmp, agno, nblocks, l2nb, results)) == -ENOSPC)
889 rc = dbAllocAny(bmp, nblocks, l2nb, results);
890
891 write_unlock:
892 IWRITE_UNLOCK(ipbmap);
893
894 return (rc);
895
896 read_unlock:
897 IREAD_UNLOCK(ipbmap);
898
899 return (rc);
900 }
901
902 /*
903 * NAME: dbReAlloc()
904 *
905 * FUNCTION: attempt to extend a current allocation by a specified
906 * number of blocks.
907 *
908 * this routine attempts to satisfy the allocation request
909 * by first trying to extend the existing allocation in
910 * place by allocating the additional blocks as the blocks
911 * immediately following the current allocation. if these
912 * blocks are not available, this routine will attempt to
913 * allocate a new set of contiguous blocks large enough
914 * to cover the existing allocation plus the additional
915 * number of blocks required.
916 *
917 * PARAMETERS:
918 * ip - pointer to in-core inode requiring allocation.
919 * blkno - starting block of the current allocation.
920 * nblocks - number of contiguous blocks within the current
921 * allocation.
922 * addnblocks - number of blocks to add to the allocation.
923 * results - on successful return, set to the starting block number
924 * of the existing allocation if the existing allocation
925 * was extended in place or to a newly allocated contiguous
926 * range if the existing allocation could not be extended
927 * in place.
928 *
929 * RETURN VALUES:
930 * 0 - success
931 * -ENOSPC - insufficient disk resources
932 * -EIO - i/o error
933 */
934 int
935 dbReAlloc(struct inode *ip,
936 s64 blkno, s64 nblocks, s64 addnblocks, s64 * results)
937 {
938 int rc;
939
940 /* try to extend the allocation in place.
941 */
942 if ((rc = dbExtend(ip, blkno, nblocks, addnblocks)) == 0) {
943 *results = blkno;
944 return (0);
945 } else {
946 if (rc != -ENOSPC)
947 return (rc);
948 }
949
950 /* could not extend the allocation in place, so allocate a
951 * new set of blocks for the entire request (i.e. try to get
952 * a range of contiguous blocks large enough to cover the
953 * existing allocation plus the additional blocks.)
954 */
955 return (dbAlloc
956 (ip, blkno + nblocks - 1, addnblocks + nblocks, results));
957 }
958
959
960 /*
961 * NAME: dbExtend()
962 *
963 * FUNCTION: attempt to extend a current allocation by a specified
964 * number of blocks.
965 *
966 * this routine attempts to satisfy the allocation request
967 * by first trying to extend the existing allocation in
968 * place by allocating the additional blocks as the blocks
969 * immediately following the current allocation.
970 *
971 * PARAMETERS:
972 * ip - pointer to in-core inode requiring allocation.
973 * blkno - starting block of the current allocation.
974 * nblocks - number of contiguous blocks within the current
975 * allocation.
976 * addnblocks - number of blocks to add to the allocation.
977 *
978 * RETURN VALUES:
979 * 0 - success
980 * -ENOSPC - insufficient disk resources
981 * -EIO - i/o error
982 */
983 static int dbExtend(struct inode *ip, s64 blkno, s64 nblocks, s64 addnblocks)
984 {
985 struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
986 s64 lblkno, lastblkno, extblkno;
987 uint rel_block;
988 struct metapage *mp;
989 struct dmap *dp;
990 int rc;
991 struct inode *ipbmap = sbi->ipbmap;
992 struct bmap *bmp;
993
994 /*
995 * We don't want a non-aligned extent to cross a page boundary
996 */
997 if (((rel_block = blkno & (sbi->nbperpage - 1))) &&
998 (rel_block + nblocks + addnblocks > sbi->nbperpage))
999 return -ENOSPC;
1000
1001 /* get the last block of the current allocation */
1002 lastblkno = blkno + nblocks - 1;
1003
1004 /* determine the block number of the block following
1005 * the existing allocation.
1006 */
1007 extblkno = lastblkno + 1;
1008
1009 IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
1010
1011 /* better be within the file system */
1012 bmp = sbi->bmap;
1013 if (lastblkno < 0 || lastblkno >= bmp->db_mapsize) {
1014 IREAD_UNLOCK(ipbmap);
1015 jfs_error(ip->i_sb, "the block is outside the filesystem\n");
1016 return -EIO;
1017 }
1018
1019 /* we'll attempt to extend the current allocation in place by
1020 * allocating the additional blocks as the blocks immediately
1021 * following the current allocation. we only try to extend the
1022 * current allocation in place if the number of additional blocks
1023 * can fit into a dmap, the last block of the current allocation
1024 * is not the last block of the file system, and the start of the
1025 * inplace extension is not on an allocation group boundary.
1026 */
1027 if (addnblocks > BPERDMAP || extblkno >= bmp->db_mapsize ||
1028 (extblkno & (bmp->db_agsize - 1)) == 0) {
1029 IREAD_UNLOCK(ipbmap);
1030 return -ENOSPC;
1031 }
1032
1033 /* get the buffer for the dmap containing the first block
1034 * of the extension.
1035 */
1036 lblkno = BLKTODMAP(extblkno, bmp->db_l2nbperpage);
1037 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
1038 if (mp == NULL) {
1039 IREAD_UNLOCK(ipbmap);
1040 return -EIO;
1041 }
1042
1043 dp = (struct dmap *) mp->data;
1044
1045 /* try to allocate the blocks immediately following the
1046 * current allocation.
1047 */
1048 rc = dbAllocNext(bmp, dp, extblkno, (int) addnblocks);
1049
1050 IREAD_UNLOCK(ipbmap);
1051
1052 /* were we successful ? */
1053 if (rc == 0)
1054 write_metapage(mp);
1055 else
1056 /* we were not successful */
1057 release_metapage(mp);
1058
1059 return (rc);
1060 }
1061
1062
1063 /*
1064 * NAME: dbAllocNext()
1065 *
1066 * FUNCTION: attempt to allocate the blocks of the specified block
1067 * range within a dmap.
1068 *
1069 * PARAMETERS:
1070 * bmp - pointer to bmap descriptor
1071 * dp - pointer to dmap.
1072 * blkno - starting block number of the range.
1073 * nblocks - number of contiguous free blocks of the range.
1074 *
1075 * RETURN VALUES:
1076 * 0 - success
1077 * -ENOSPC - insufficient disk resources
1078 * -EIO - i/o error
1079 *
1080 * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1081 */
1082 static int dbAllocNext(struct bmap * bmp, struct dmap * dp, s64 blkno,
1083 int nblocks)
1084 {
1085 int dbitno, word, rembits, nb, nwords, wbitno, nw;
1086 int l2size;
1087 s8 *leaf;
1088 u32 mask;
1089
1090 if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1091 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmap page\n");
1092 return -EIO;
1093 }
1094
1095 /* pick up a pointer to the leaves of the dmap tree.
1096 */
1097 leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1098
1099 /* determine the bit number and word within the dmap of the
1100 * starting block.
1101 */
1102 dbitno = blkno & (BPERDMAP - 1);
1103 word = dbitno >> L2DBWORD;
1104
1105 /* check if the specified block range is contained within
1106 * this dmap.
1107 */
1108 if (dbitno + nblocks > BPERDMAP)
1109 return -ENOSPC;
1110
1111 /* check if the starting leaf indicates that anything
1112 * is free.
1113 */
1114 if (leaf[word] == NOFREE)
1115 return -ENOSPC;
1116
1117 /* check the dmaps words corresponding to block range to see
1118 * if the block range is free. not all bits of the first and
1119 * last words may be contained within the block range. if this
1120 * is the case, we'll work against those words (i.e. partial first
1121 * and/or last) on an individual basis (a single pass) and examine
1122 * the actual bits to determine if they are free. a single pass
1123 * will be used for all dmap words fully contained within the
1124 * specified range. within this pass, the leaves of the dmap
1125 * tree will be examined to determine if the blocks are free. a
1126 * single leaf may describe the free space of multiple dmap
1127 * words, so we may visit only a subset of the actual leaves
1128 * corresponding to the dmap words of the block range.
1129 */
1130 for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
1131 /* determine the bit number within the word and
1132 * the number of bits within the word.
1133 */
1134 wbitno = dbitno & (DBWORD - 1);
1135 nb = min(rembits, DBWORD - wbitno);
1136
1137 /* check if only part of the word is to be examined.
1138 */
1139 if (nb < DBWORD) {
1140 /* check if the bits are free.
1141 */
1142 mask = (ONES << (DBWORD - nb) >> wbitno);
1143 if ((mask & ~le32_to_cpu(dp->wmap[word])) != mask)
1144 return -ENOSPC;
1145
1146 word += 1;
1147 } else {
1148 /* one or more dmap words are fully contained
1149 * within the block range. determine how many
1150 * words and how many bits.
1151 */
1152 nwords = rembits >> L2DBWORD;
1153 nb = nwords << L2DBWORD;
1154
1155 /* now examine the appropriate leaves to determine
1156 * if the blocks are free.
1157 */
1158 while (nwords > 0) {
1159 /* does the leaf describe any free space ?
1160 */
1161 if (leaf[word] < BUDMIN)
1162 return -ENOSPC;
1163
1164 /* determine the l2 number of bits provided
1165 * by this leaf.
1166 */
1167 l2size =
1168 min_t(int, leaf[word], NLSTOL2BSZ(nwords));
1169
1170 /* determine how many words were handled.
1171 */
1172 nw = BUDSIZE(l2size, BUDMIN);
1173
1174 nwords -= nw;
1175 word += nw;
1176 }
1177 }
1178 }
1179
1180 /* allocate the blocks.
1181 */
1182 return (dbAllocDmap(bmp, dp, blkno, nblocks));
1183 }
1184
1185
1186 /*
1187 * NAME: dbAllocNear()
1188 *
1189 * FUNCTION: attempt to allocate a number of contiguous free blocks near
1190 * a specified block (hint) within a dmap.
1191 *
1192 * starting with the dmap leaf that covers the hint, we'll
1193 * check the next four contiguous leaves for sufficient free
1194 * space. if sufficient free space is found, we'll allocate
1195 * the desired free space.
1196 *
1197 * PARAMETERS:
1198 * bmp - pointer to bmap descriptor
1199 * dp - pointer to dmap.
1200 * blkno - block number to allocate near.
1201 * nblocks - actual number of contiguous free blocks desired.
1202 * l2nb - log2 number of contiguous free blocks desired.
1203 * results - on successful return, set to the starting block number
1204 * of the newly allocated range.
1205 *
1206 * RETURN VALUES:
1207 * 0 - success
1208 * -ENOSPC - insufficient disk resources
1209 * -EIO - i/o error
1210 *
1211 * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
1212 */
1213 static int
1214 dbAllocNear(struct bmap * bmp,
1215 struct dmap * dp, s64 blkno, int nblocks, int l2nb, s64 * results)
1216 {
1217 int word, lword, rc;
1218 s8 *leaf;
1219
1220 if (dp->tree.leafidx != cpu_to_le32(LEAFIND)) {
1221 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmap page\n");
1222 return -EIO;
1223 }
1224
1225 leaf = dp->tree.stree + le32_to_cpu(dp->tree.leafidx);
1226
1227 /* determine the word within the dmap that holds the hint
1228 * (i.e. blkno). also, determine the last word in the dmap
1229 * that we'll include in our examination.
1230 */
1231 word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
1232 lword = min(word + 4, LPERDMAP);
1233
1234 /* examine the leaves for sufficient free space.
1235 */
1236 for (; word < lword; word++) {
1237 /* does the leaf describe sufficient free space ?
1238 */
1239 if (leaf[word] < l2nb)
1240 continue;
1241
1242 /* determine the block number within the file system
1243 * of the first block described by this dmap word.
1244 */
1245 blkno = le64_to_cpu(dp->start) + (word << L2DBWORD);
1246
1247 /* if not all bits of the dmap word are free, get the
1248 * starting bit number within the dmap word of the required
1249 * string of free bits and adjust the block number with the
1250 * value.
1251 */
1252 if (leaf[word] < BUDMIN)
1253 blkno +=
1254 dbFindBits(le32_to_cpu(dp->wmap[word]), l2nb);
1255
1256 /* allocate the blocks.
1257 */
1258 if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1259 *results = blkno;
1260
1261 return (rc);
1262 }
1263
1264 return -ENOSPC;
1265 }
1266
1267
1268 /*
1269 * NAME: dbAllocAG()
1270 *
1271 * FUNCTION: attempt to allocate the specified number of contiguous
1272 * free blocks within the specified allocation group.
1273 *
1274 * unless the allocation group size is equal to the number
1275 * of blocks per dmap, the dmap control pages will be used to
1276 * find the required free space, if available. we start the
1277 * search at the highest dmap control page level which
1278 * distinctly describes the allocation group's free space
1279 * (i.e. the highest level at which the allocation group's
1280 * free space is not mixed in with that of any other group).
1281 * in addition, we start the search within this level at a
1282 * height of the dmapctl dmtree at which the nodes distinctly
1283 * describe the allocation group's free space. at this height,
1284 * the allocation group's free space may be represented by 1
1285 * or two sub-trees, depending on the allocation group size.
1286 * we search the top nodes of these subtrees left to right for
1287 * sufficient free space. if sufficient free space is found,
1288 * the subtree is searched to find the leftmost leaf that
1289 * has free space. once we have made it to the leaf, we
1290 * move the search to the next lower level dmap control page
1291 * corresponding to this leaf. we continue down the dmap control
1292 * pages until we find the dmap that contains or starts the
1293 * sufficient free space and we allocate at this dmap.
1294 *
1295 * if the allocation group size is equal to the dmap size,
1296 * we'll start at the dmap corresponding to the allocation
1297 * group and attempt the allocation at this level.
1298 *
1299 * the dmap control page search is also not performed if the
1300 * allocation group is completely free and we go to the first
1301 * dmap of the allocation group to do the allocation. this is
1302 * done because the allocation group may be part (not the first
1303 * part) of a larger binary buddy system, causing the dmap
1304 * control pages to indicate no free space (NOFREE) within
1305 * the allocation group.
1306 *
1307 * PARAMETERS:
1308 * bmp - pointer to bmap descriptor
1309 * agno - allocation group number.
1310 * nblocks - actual number of contiguous free blocks desired.
1311 * l2nb - log2 number of contiguous free blocks desired.
1312 * results - on successful return, set to the starting block number
1313 * of the newly allocated range.
1314 *
1315 * RETURN VALUES:
1316 * 0 - success
1317 * -ENOSPC - insufficient disk resources
1318 * -EIO - i/o error
1319 *
1320 * note: IWRITE_LOCK(ipmap) held on entry/exit;
1321 */
1322 static int
1323 dbAllocAG(struct bmap * bmp, int agno, s64 nblocks, int l2nb, s64 * results)
1324 {
1325 struct metapage *mp;
1326 struct dmapctl *dcp;
1327 int rc, ti, i, k, m, n, agperlev;
1328 s64 blkno, lblkno;
1329 int budmin;
1330
1331 /* allocation request should not be for more than the
1332 * allocation group size.
1333 */
1334 if (l2nb > bmp->db_agl2size) {
1335 jfs_error(bmp->db_ipbmap->i_sb,
1336 "allocation request is larger than the allocation group size\n");
1337 return -EIO;
1338 }
1339
1340 /* determine the starting block number of the allocation
1341 * group.
1342 */
1343 blkno = (s64) agno << bmp->db_agl2size;
1344
1345 /* check if the allocation group size is the minimum allocation
1346 * group size or if the allocation group is completely free. if
1347 * the allocation group size is the minimum size of BPERDMAP (i.e.
1348 * 1 dmap), there is no need to search the dmap control page (below)
1349 * that fully describes the allocation group since the allocation
1350 * group is already fully described by a dmap. in this case, we
1351 * just call dbAllocCtl() to search the dmap tree and allocate the
1352 * required space if available.
1353 *
1354 * if the allocation group is completely free, dbAllocCtl() is
1355 * also called to allocate the required space. this is done for
1356 * two reasons. first, it makes no sense searching the dmap control
1357 * pages for free space when we know that free space exists. second,
1358 * the dmap control pages may indicate that the allocation group
1359 * has no free space if the allocation group is part (not the first
1360 * part) of a larger binary buddy system.
1361 */
1362 if (bmp->db_agsize == BPERDMAP
1363 || bmp->db_agfree[agno] == bmp->db_agsize) {
1364 rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1365 if ((rc == -ENOSPC) &&
1366 (bmp->db_agfree[agno] == bmp->db_agsize)) {
1367 printk(KERN_ERR "blkno = %Lx, blocks = %Lx\n",
1368 (unsigned long long) blkno,
1369 (unsigned long long) nblocks);
1370 jfs_error(bmp->db_ipbmap->i_sb,
1371 "dbAllocCtl failed in free AG\n");
1372 }
1373 return (rc);
1374 }
1375
1376 /* the buffer for the dmap control page that fully describes the
1377 * allocation group.
1378 */
1379 lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, bmp->db_aglevel);
1380 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1381 if (mp == NULL)
1382 return -EIO;
1383 dcp = (struct dmapctl *) mp->data;
1384 budmin = dcp->budmin;
1385
1386 if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1387 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page\n");
1388 release_metapage(mp);
1389 return -EIO;
1390 }
1391
1392 /* search the subtree(s) of the dmap control page that describes
1393 * the allocation group, looking for sufficient free space. to begin,
1394 * determine how many allocation groups are represented in a dmap
1395 * control page at the control page level (i.e. L0, L1, L2) that
1396 * fully describes an allocation group. next, determine the starting
1397 * tree index of this allocation group within the control page.
1398 */
1399 agperlev =
1400 (1 << (L2LPERCTL - (bmp->db_agheight << 1))) / bmp->db_agwidth;
1401 ti = bmp->db_agstart + bmp->db_agwidth * (agno & (agperlev - 1));
1402
1403 /* dmap control page trees fan-out by 4 and a single allocation
1404 * group may be described by 1 or 2 subtrees within the ag level
1405 * dmap control page, depending upon the ag size. examine the ag's
1406 * subtrees for sufficient free space, starting with the leftmost
1407 * subtree.
1408 */
1409 for (i = 0; i < bmp->db_agwidth; i++, ti++) {
1410 /* is there sufficient free space ?
1411 */
1412 if (l2nb > dcp->stree[ti])
1413 continue;
1414
1415 /* sufficient free space found in a subtree. now search down
1416 * the subtree to find the leftmost leaf that describes this
1417 * free space.
1418 */
1419 for (k = bmp->db_agheight; k > 0; k--) {
1420 for (n = 0, m = (ti << 2) + 1; n < 4; n++) {
1421 if (l2nb <= dcp->stree[m + n]) {
1422 ti = m + n;
1423 break;
1424 }
1425 }
1426 if (n == 4) {
1427 jfs_error(bmp->db_ipbmap->i_sb,
1428 "failed descending stree\n");
1429 release_metapage(mp);
1430 return -EIO;
1431 }
1432 }
1433
1434 /* determine the block number within the file system
1435 * that corresponds to this leaf.
1436 */
1437 if (bmp->db_aglevel == 2)
1438 blkno = 0;
1439 else if (bmp->db_aglevel == 1)
1440 blkno &= ~(MAXL1SIZE - 1);
1441 else /* bmp->db_aglevel == 0 */
1442 blkno &= ~(MAXL0SIZE - 1);
1443
1444 blkno +=
1445 ((s64) (ti - le32_to_cpu(dcp->leafidx))) << budmin;
1446
1447 /* release the buffer in preparation for going down
1448 * the next level of dmap control pages.
1449 */
1450 release_metapage(mp);
1451
1452 /* check if we need to continue to search down the lower
1453 * level dmap control pages. we need to if the number of
1454 * blocks required is less than maximum number of blocks
1455 * described at the next lower level.
1456 */
1457 if (l2nb < budmin) {
1458
1459 /* search the lower level dmap control pages to get
1460 * the starting block number of the dmap that
1461 * contains or starts off the free space.
1462 */
1463 if ((rc =
1464 dbFindCtl(bmp, l2nb, bmp->db_aglevel - 1,
1465 &blkno))) {
1466 if (rc == -ENOSPC) {
1467 jfs_error(bmp->db_ipbmap->i_sb,
1468 "control page inconsistent\n");
1469 return -EIO;
1470 }
1471 return (rc);
1472 }
1473 }
1474
1475 /* allocate the blocks.
1476 */
1477 rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1478 if (rc == -ENOSPC) {
1479 jfs_error(bmp->db_ipbmap->i_sb,
1480 "unable to allocate blocks\n");
1481 rc = -EIO;
1482 }
1483 return (rc);
1484 }
1485
1486 /* no space in the allocation group. release the buffer and
1487 * return -ENOSPC.
1488 */
1489 release_metapage(mp);
1490
1491 return -ENOSPC;
1492 }
1493
1494
1495 /*
1496 * NAME: dbAllocAny()
1497 *
1498 * FUNCTION: attempt to allocate the specified number of contiguous
1499 * free blocks anywhere in the file system.
1500 *
1501 * dbAllocAny() attempts to find the sufficient free space by
1502 * searching down the dmap control pages, starting with the
1503 * highest level (i.e. L0, L1, L2) control page. if free space
1504 * large enough to satisfy the desired free space is found, the
1505 * desired free space is allocated.
1506 *
1507 * PARAMETERS:
1508 * bmp - pointer to bmap descriptor
1509 * nblocks - actual number of contiguous free blocks desired.
1510 * l2nb - log2 number of contiguous free blocks desired.
1511 * results - on successful return, set to the starting block number
1512 * of the newly allocated range.
1513 *
1514 * RETURN VALUES:
1515 * 0 - success
1516 * -ENOSPC - insufficient disk resources
1517 * -EIO - i/o error
1518 *
1519 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1520 */
1521 static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results)
1522 {
1523 int rc;
1524 s64 blkno = 0;
1525
1526 /* starting with the top level dmap control page, search
1527 * down the dmap control levels for sufficient free space.
1528 * if free space is found, dbFindCtl() returns the starting
1529 * block number of the dmap that contains or starts off the
1530 * range of free space.
1531 */
1532 if ((rc = dbFindCtl(bmp, l2nb, bmp->db_maxlevel, &blkno)))
1533 return (rc);
1534
1535 /* allocate the blocks.
1536 */
1537 rc = dbAllocCtl(bmp, nblocks, l2nb, blkno, results);
1538 if (rc == -ENOSPC) {
1539 jfs_error(bmp->db_ipbmap->i_sb, "unable to allocate blocks\n");
1540 return -EIO;
1541 }
1542 return (rc);
1543 }
1544
1545
1546 /*
1547 * NAME: dbDiscardAG()
1548 *
1549 * FUNCTION: attempt to discard (TRIM) all free blocks of specific AG
1550 *
1551 * algorithm:
1552 * 1) allocate blocks, as large as possible and save them
1553 * while holding IWRITE_LOCK on ipbmap
1554 * 2) trim all these saved block/length values
1555 * 3) mark the blocks free again
1556 *
1557 * benefit:
1558 * - we work only on one ag at some time, minimizing how long we
1559 * need to lock ipbmap
1560 * - reading / writing the fs is possible most time, even on
1561 * trimming
1562 *
1563 * downside:
1564 * - we write two times to the dmapctl and dmap pages
1565 * - but for me, this seems the best way, better ideas?
1566 * /TR 2012
1567 *
1568 * PARAMETERS:
1569 * ip - pointer to in-core inode
1570 * agno - ag to trim
1571 * minlen - minimum value of contiguous blocks
1572 *
1573 * RETURN VALUES:
1574 * s64 - actual number of blocks trimmed
1575 */
1576 s64 dbDiscardAG(struct inode *ip, int agno, s64 minlen)
1577 {
1578 struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
1579 struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
1580 s64 nblocks, blkno;
1581 u64 trimmed = 0;
1582 int rc, l2nb;
1583 struct super_block *sb = ipbmap->i_sb;
1584
1585 struct range2trim {
1586 u64 blkno;
1587 u64 nblocks;
1588 } *totrim, *tt;
1589
1590 /* max blkno / nblocks pairs to trim */
1591 int count = 0, range_cnt;
1592 u64 max_ranges;
1593
1594 /* prevent others from writing new stuff here, while trimming */
1595 IWRITE_LOCK(ipbmap, RDWRLOCK_DMAP);
1596
1597 nblocks = bmp->db_agfree[agno];
1598 max_ranges = nblocks;
1599 do_div(max_ranges, minlen);
1600 range_cnt = min_t(u64, max_ranges + 1, 32 * 1024);
1601 totrim = kmalloc_array(range_cnt, sizeof(struct range2trim), GFP_NOFS);
1602 if (totrim == NULL) {
1603 jfs_error(bmp->db_ipbmap->i_sb, "no memory for trim array\n");
1604 IWRITE_UNLOCK(ipbmap);
1605 return 0;
1606 }
1607
1608 tt = totrim;
1609 while (nblocks >= minlen) {
1610 l2nb = BLKSTOL2(nblocks);
1611
1612 /* 0 = okay, -EIO = fatal, -ENOSPC -> try smaller block */
1613 rc = dbAllocAG(bmp, agno, nblocks, l2nb, &blkno);
1614 if (rc == 0) {
1615 tt->blkno = blkno;
1616 tt->nblocks = nblocks;
1617 tt++; count++;
1618
1619 /* the whole ag is free, trim now */
1620 if (bmp->db_agfree[agno] == 0)
1621 break;
1622
1623 /* give a hint for the next while */
1624 nblocks = bmp->db_agfree[agno];
1625 continue;
1626 } else if (rc == -ENOSPC) {
1627 /* search for next smaller log2 block */
1628 l2nb = BLKSTOL2(nblocks) - 1;
1629 if (unlikely(l2nb < 0))
1630 break;
1631 nblocks = 1LL << l2nb;
1632 } else {
1633 /* Trim any already allocated blocks */
1634 jfs_error(bmp->db_ipbmap->i_sb, "-EIO\n");
1635 break;
1636 }
1637
1638 /* check, if our trim array is full */
1639 if (unlikely(count >= range_cnt - 1))
1640 break;
1641 }
1642 IWRITE_UNLOCK(ipbmap);
1643
1644 tt->nblocks = 0; /* mark the current end */
1645 for (tt = totrim; tt->nblocks != 0; tt++) {
1646 /* when mounted with online discard, dbFree() will
1647 * call jfs_issue_discard() itself */
1648 if (!(JFS_SBI(sb)->flag & JFS_DISCARD))
1649 jfs_issue_discard(ip, tt->blkno, tt->nblocks);
1650 dbFree(ip, tt->blkno, tt->nblocks);
1651 trimmed += tt->nblocks;
1652 }
1653 kfree(totrim);
1654
1655 return trimmed;
1656 }
1657
1658 /*
1659 * NAME: dbFindCtl()
1660 *
1661 * FUNCTION: starting at a specified dmap control page level and block
1662 * number, search down the dmap control levels for a range of
1663 * contiguous free blocks large enough to satisfy an allocation
1664 * request for the specified number of free blocks.
1665 *
1666 * if sufficient contiguous free blocks are found, this routine
1667 * returns the starting block number within a dmap page that
1668 * contains or starts a range of contiqious free blocks that
1669 * is sufficient in size.
1670 *
1671 * PARAMETERS:
1672 * bmp - pointer to bmap descriptor
1673 * level - starting dmap control page level.
1674 * l2nb - log2 number of contiguous free blocks desired.
1675 * *blkno - on entry, starting block number for conducting the search.
1676 * on successful return, the first block within a dmap page
1677 * that contains or starts a range of contiguous free blocks.
1678 *
1679 * RETURN VALUES:
1680 * 0 - success
1681 * -ENOSPC - insufficient disk resources
1682 * -EIO - i/o error
1683 *
1684 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1685 */
1686 static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno)
1687 {
1688 int rc, leafidx, lev;
1689 s64 b, lblkno;
1690 struct dmapctl *dcp;
1691 int budmin;
1692 struct metapage *mp;
1693
1694 /* starting at the specified dmap control page level and block
1695 * number, search down the dmap control levels for the starting
1696 * block number of a dmap page that contains or starts off
1697 * sufficient free blocks.
1698 */
1699 for (lev = level, b = *blkno; lev >= 0; lev--) {
1700 /* get the buffer of the dmap control page for the block
1701 * number and level (i.e. L0, L1, L2).
1702 */
1703 lblkno = BLKTOCTL(b, bmp->db_l2nbperpage, lev);
1704 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1705 if (mp == NULL)
1706 return -EIO;
1707 dcp = (struct dmapctl *) mp->data;
1708 budmin = dcp->budmin;
1709
1710 if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1711 jfs_error(bmp->db_ipbmap->i_sb,
1712 "Corrupt dmapctl page\n");
1713 release_metapage(mp);
1714 return -EIO;
1715 }
1716
1717 /* search the tree within the dmap control page for
1718 * sufficient free space. if sufficient free space is found,
1719 * dbFindLeaf() returns the index of the leaf at which
1720 * free space was found.
1721 */
1722 rc = dbFindLeaf((dmtree_t *) dcp, l2nb, &leafidx, true);
1723
1724 /* release the buffer.
1725 */
1726 release_metapage(mp);
1727
1728 /* space found ?
1729 */
1730 if (rc) {
1731 if (lev != level) {
1732 jfs_error(bmp->db_ipbmap->i_sb,
1733 "dmap inconsistent\n");
1734 return -EIO;
1735 }
1736 return -ENOSPC;
1737 }
1738
1739 /* adjust the block number to reflect the location within
1740 * the dmap control page (i.e. the leaf) at which free
1741 * space was found.
1742 */
1743 b += (((s64) leafidx) << budmin);
1744
1745 /* we stop the search at this dmap control page level if
1746 * the number of blocks required is greater than or equal
1747 * to the maximum number of blocks described at the next
1748 * (lower) level.
1749 */
1750 if (l2nb >= budmin)
1751 break;
1752 }
1753
1754 *blkno = b;
1755 return (0);
1756 }
1757
1758
1759 /*
1760 * NAME: dbAllocCtl()
1761 *
1762 * FUNCTION: attempt to allocate a specified number of contiguous
1763 * blocks starting within a specific dmap.
1764 *
1765 * this routine is called by higher level routines that search
1766 * the dmap control pages above the actual dmaps for contiguous
1767 * free space. the result of successful searches by these
1768 * routines are the starting block numbers within dmaps, with
1769 * the dmaps themselves containing the desired contiguous free
1770 * space or starting a contiguous free space of desired size
1771 * that is made up of the blocks of one or more dmaps. these
1772 * calls should not fail due to insufficent resources.
1773 *
1774 * this routine is called in some cases where it is not known
1775 * whether it will fail due to insufficient resources. more
1776 * specifically, this occurs when allocating from an allocation
1777 * group whose size is equal to the number of blocks per dmap.
1778 * in this case, the dmap control pages are not examined prior
1779 * to calling this routine (to save pathlength) and the call
1780 * might fail.
1781 *
1782 * for a request size that fits within a dmap, this routine relies
1783 * upon the dmap's dmtree to find the requested contiguous free
1784 * space. for request sizes that are larger than a dmap, the
1785 * requested free space will start at the first block of the
1786 * first dmap (i.e. blkno).
1787 *
1788 * PARAMETERS:
1789 * bmp - pointer to bmap descriptor
1790 * nblocks - actual number of contiguous free blocks to allocate.
1791 * l2nb - log2 number of contiguous free blocks to allocate.
1792 * blkno - starting block number of the dmap to start the allocation
1793 * from.
1794 * results - on successful return, set to the starting block number
1795 * of the newly allocated range.
1796 *
1797 * RETURN VALUES:
1798 * 0 - success
1799 * -ENOSPC - insufficient disk resources
1800 * -EIO - i/o error
1801 *
1802 * serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1803 */
1804 static int
1805 dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno, s64 * results)
1806 {
1807 int rc, nb;
1808 s64 b, lblkno, n;
1809 struct metapage *mp;
1810 struct dmap *dp;
1811
1812 /* check if the allocation request is confined to a single dmap.
1813 */
1814 if (l2nb <= L2BPERDMAP) {
1815 /* get the buffer for the dmap.
1816 */
1817 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
1818 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1819 if (mp == NULL)
1820 return -EIO;
1821 dp = (struct dmap *) mp->data;
1822
1823 /* try to allocate the blocks.
1824 */
1825 rc = dbAllocDmapLev(bmp, dp, (int) nblocks, l2nb, results);
1826 if (rc == 0)
1827 mark_metapage_dirty(mp);
1828
1829 release_metapage(mp);
1830
1831 return (rc);
1832 }
1833
1834 /* allocation request involving multiple dmaps. it must start on
1835 * a dmap boundary.
1836 */
1837 assert((blkno & (BPERDMAP - 1)) == 0);
1838
1839 /* allocate the blocks dmap by dmap.
1840 */
1841 for (n = nblocks, b = blkno; n > 0; n -= nb, b += nb) {
1842 /* get the buffer for the dmap.
1843 */
1844 lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1845 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1846 if (mp == NULL) {
1847 rc = -EIO;
1848 goto backout;
1849 }
1850 dp = (struct dmap *) mp->data;
1851
1852 /* the dmap better be all free.
1853 */
1854 if (dp->tree.stree[ROOT] != L2BPERDMAP) {
1855 release_metapage(mp);
1856 jfs_error(bmp->db_ipbmap->i_sb,
1857 "the dmap is not all free\n");
1858 rc = -EIO;
1859 goto backout;
1860 }
1861
1862 /* determine how many blocks to allocate from this dmap.
1863 */
1864 nb = min_t(s64, n, BPERDMAP);
1865
1866 /* allocate the blocks from the dmap.
1867 */
1868 if ((rc = dbAllocDmap(bmp, dp, b, nb))) {
1869 release_metapage(mp);
1870 goto backout;
1871 }
1872
1873 /* write the buffer.
1874 */
1875 write_metapage(mp);
1876 }
1877
1878 /* set the results (starting block number) and return.
1879 */
1880 *results = blkno;
1881 return (0);
1882
1883 /* something failed in handling an allocation request involving
1884 * multiple dmaps. we'll try to clean up by backing out any
1885 * allocation that has already happened for this request. if
1886 * we fail in backing out the allocation, we'll mark the file
1887 * system to indicate that blocks have been leaked.
1888 */
1889 backout:
1890
1891 /* try to backout the allocations dmap by dmap.
1892 */
1893 for (n = nblocks - n, b = blkno; n > 0;
1894 n -= BPERDMAP, b += BPERDMAP) {
1895 /* get the buffer for this dmap.
1896 */
1897 lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1898 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1899 if (mp == NULL) {
1900 /* could not back out. mark the file system
1901 * to indicate that we have leaked blocks.
1902 */
1903 jfs_error(bmp->db_ipbmap->i_sb,
1904 "I/O Error: Block Leakage\n");
1905 continue;
1906 }
1907 dp = (struct dmap *) mp->data;
1908
1909 /* free the blocks is this dmap.
1910 */
1911 if (dbFreeDmap(bmp, dp, b, BPERDMAP)) {
1912 /* could not back out. mark the file system
1913 * to indicate that we have leaked blocks.
1914 */
1915 release_metapage(mp);
1916 jfs_error(bmp->db_ipbmap->i_sb, "Block Leakage\n");
1917 continue;
1918 }
1919
1920 /* write the buffer.
1921 */
1922 write_metapage(mp);
1923 }
1924
1925 return (rc);
1926 }
1927
1928
1929 /*
1930 * NAME: dbAllocDmapLev()
1931 *
1932 * FUNCTION: attempt to allocate a specified number of contiguous blocks
1933 * from a specified dmap.
1934 *
1935 * this routine checks if the contiguous blocks are available.
1936 * if so, nblocks of blocks are allocated; otherwise, ENOSPC is
1937 * returned.
1938 *
1939 * PARAMETERS:
1940 * mp - pointer to bmap descriptor
1941 * dp - pointer to dmap to attempt to allocate blocks from.
1942 * l2nb - log2 number of contiguous block desired.
1943 * nblocks - actual number of contiguous block desired.
1944 * results - on successful return, set to the starting block number
1945 * of the newly allocated range.
1946 *
1947 * RETURN VALUES:
1948 * 0 - success
1949 * -ENOSPC - insufficient disk resources
1950 * -EIO - i/o error
1951 *
1952 * serialization: IREAD_LOCK(ipbmap), e.g., from dbAlloc(), or
1953 * IWRITE_LOCK(ipbmap), e.g., dbAllocCtl(), held on entry/exit;
1954 */
1955 static int
1956 dbAllocDmapLev(struct bmap * bmp,
1957 struct dmap * dp, int nblocks, int l2nb, s64 * results)
1958 {
1959 s64 blkno;
1960 int leafidx, rc;
1961
1962 /* can't be more than a dmaps worth of blocks */
1963 assert(l2nb <= L2BPERDMAP);
1964
1965 /* search the tree within the dmap page for sufficient
1966 * free space. if sufficient free space is found, dbFindLeaf()
1967 * returns the index of the leaf at which free space was found.
1968 */
1969 if (dbFindLeaf((dmtree_t *) &dp->tree, l2nb, &leafidx, false))
1970 return -ENOSPC;
1971
1972 if (leafidx < 0)
1973 return -EIO;
1974
1975 /* determine the block number within the file system corresponding
1976 * to the leaf at which free space was found.
1977 */
1978 blkno = le64_to_cpu(dp->start) + (leafidx << L2DBWORD);
1979
1980 /* if not all bits of the dmap word are free, get the starting
1981 * bit number within the dmap word of the required string of free
1982 * bits and adjust the block number with this value.
1983 */
1984 if (dp->tree.stree[leafidx + LEAFIND] < BUDMIN)
1985 blkno += dbFindBits(le32_to_cpu(dp->wmap[leafidx]), l2nb);
1986
1987 /* allocate the blocks */
1988 if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1989 *results = blkno;
1990
1991 return (rc);
1992 }
1993
1994
1995 /*
1996 * NAME: dbAllocDmap()
1997 *
1998 * FUNCTION: adjust the disk allocation map to reflect the allocation
1999 * of a specified block range within a dmap.
2000 *
2001 * this routine allocates the specified blocks from the dmap
2002 * through a call to dbAllocBits(). if the allocation of the
2003 * block range causes the maximum string of free blocks within
2004 * the dmap to change (i.e. the value of the root of the dmap's
2005 * dmtree), this routine will cause this change to be reflected
2006 * up through the appropriate levels of the dmap control pages
2007 * by a call to dbAdjCtl() for the L0 dmap control page that
2008 * covers this dmap.
2009 *
2010 * PARAMETERS:
2011 * bmp - pointer to bmap descriptor
2012 * dp - pointer to dmap to allocate the block range from.
2013 * blkno - starting block number of the block to be allocated.
2014 * nblocks - number of blocks to be allocated.
2015 *
2016 * RETURN VALUES:
2017 * 0 - success
2018 * -EIO - i/o error
2019 *
2020 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2021 */
2022 static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2023 int nblocks)
2024 {
2025 s8 oldroot;
2026 int rc;
2027
2028 /* save the current value of the root (i.e. maximum free string)
2029 * of the dmap tree.
2030 */
2031 oldroot = dp->tree.stree[ROOT];
2032
2033 /* allocate the specified (blocks) bits */
2034 dbAllocBits(bmp, dp, blkno, nblocks);
2035
2036 /* if the root has not changed, done. */
2037 if (dp->tree.stree[ROOT] == oldroot)
2038 return (0);
2039
2040 /* root changed. bubble the change up to the dmap control pages.
2041 * if the adjustment of the upper level control pages fails,
2042 * backout the bit allocation (thus making everything consistent).
2043 */
2044 if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 1, 0)))
2045 dbFreeBits(bmp, dp, blkno, nblocks);
2046
2047 return (rc);
2048 }
2049
2050
2051 /*
2052 * NAME: dbFreeDmap()
2053 *
2054 * FUNCTION: adjust the disk allocation map to reflect the allocation
2055 * of a specified block range within a dmap.
2056 *
2057 * this routine frees the specified blocks from the dmap through
2058 * a call to dbFreeBits(). if the deallocation of the block range
2059 * causes the maximum string of free blocks within the dmap to
2060 * change (i.e. the value of the root of the dmap's dmtree), this
2061 * routine will cause this change to be reflected up through the
2062 * appropriate levels of the dmap control pages by a call to
2063 * dbAdjCtl() for the L0 dmap control page that covers this dmap.
2064 *
2065 * PARAMETERS:
2066 * bmp - pointer to bmap descriptor
2067 * dp - pointer to dmap to free the block range from.
2068 * blkno - starting block number of the block to be freed.
2069 * nblocks - number of blocks to be freed.
2070 *
2071 * RETURN VALUES:
2072 * 0 - success
2073 * -EIO - i/o error
2074 *
2075 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2076 */
2077 static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2078 int nblocks)
2079 {
2080 s8 oldroot;
2081 int rc = 0, word;
2082
2083 /* save the current value of the root (i.e. maximum free string)
2084 * of the dmap tree.
2085 */
2086 oldroot = dp->tree.stree[ROOT];
2087
2088 /* free the specified (blocks) bits */
2089 rc = dbFreeBits(bmp, dp, blkno, nblocks);
2090
2091 /* if error or the root has not changed, done. */
2092 if (rc || (dp->tree.stree[ROOT] == oldroot))
2093 return (rc);
2094
2095 /* root changed. bubble the change up to the dmap control pages.
2096 * if the adjustment of the upper level control pages fails,
2097 * backout the deallocation.
2098 */
2099 if ((rc = dbAdjCtl(bmp, blkno, dp->tree.stree[ROOT], 0, 0))) {
2100 word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
2101
2102 /* as part of backing out the deallocation, we will have
2103 * to back split the dmap tree if the deallocation caused
2104 * the freed blocks to become part of a larger binary buddy
2105 * system.
2106 */
2107 if (dp->tree.stree[word] == NOFREE)
2108 dbBackSplit((dmtree_t *)&dp->tree, word, false);
2109
2110 dbAllocBits(bmp, dp, blkno, nblocks);
2111 }
2112
2113 return (rc);
2114 }
2115
2116
2117 /*
2118 * NAME: dbAllocBits()
2119 *
2120 * FUNCTION: allocate a specified block range from a dmap.
2121 *
2122 * this routine updates the dmap to reflect the working
2123 * state allocation of the specified block range. it directly
2124 * updates the bits of the working map and causes the adjustment
2125 * of the binary buddy system described by the dmap's dmtree
2126 * leaves to reflect the bits allocated. it also causes the
2127 * dmap's dmtree, as a whole, to reflect the allocated range.
2128 *
2129 * PARAMETERS:
2130 * bmp - pointer to bmap descriptor
2131 * dp - pointer to dmap to allocate bits from.
2132 * blkno - starting block number of the bits to be allocated.
2133 * nblocks - number of bits to be allocated.
2134 *
2135 * RETURN VALUES: none
2136 *
2137 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2138 */
2139 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2140 int nblocks)
2141 {
2142 int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2143 dmtree_t *tp = (dmtree_t *) & dp->tree;
2144 int size;
2145 s8 *leaf;
2146
2147 /* pick up a pointer to the leaves of the dmap tree */
2148 leaf = dp->tree.stree + LEAFIND;
2149
2150 /* determine the bit number and word within the dmap of the
2151 * starting block.
2152 */
2153 dbitno = blkno & (BPERDMAP - 1);
2154 word = dbitno >> L2DBWORD;
2155
2156 /* block range better be within the dmap */
2157 assert(dbitno + nblocks <= BPERDMAP);
2158
2159 /* allocate the bits of the dmap's words corresponding to the block
2160 * range. not all bits of the first and last words may be contained
2161 * within the block range. if this is the case, we'll work against
2162 * those words (i.e. partial first and/or last) on an individual basis
2163 * (a single pass), allocating the bits of interest by hand and
2164 * updating the leaf corresponding to the dmap word. a single pass
2165 * will be used for all dmap words fully contained within the
2166 * specified range. within this pass, the bits of all fully contained
2167 * dmap words will be marked as free in a single shot and the leaves
2168 * will be updated. a single leaf may describe the free space of
2169 * multiple dmap words, so we may update only a subset of the actual
2170 * leaves corresponding to the dmap words of the block range.
2171 */
2172 for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2173 /* determine the bit number within the word and
2174 * the number of bits within the word.
2175 */
2176 wbitno = dbitno & (DBWORD - 1);
2177 nb = min(rembits, DBWORD - wbitno);
2178
2179 /* check if only part of a word is to be allocated.
2180 */
2181 if (nb < DBWORD) {
2182 /* allocate (set to 1) the appropriate bits within
2183 * this dmap word.
2184 */
2185 dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
2186 >> wbitno);
2187
2188 /* update the leaf for this dmap word. in addition
2189 * to setting the leaf value to the binary buddy max
2190 * of the updated dmap word, dbSplit() will split
2191 * the binary system of the leaves if need be.
2192 */
2193 dbSplit(tp, word, BUDMIN,
2194 dbMaxBud((u8 *)&dp->wmap[word]), false);
2195
2196 word += 1;
2197 } else {
2198 /* one or more dmap words are fully contained
2199 * within the block range. determine how many
2200 * words and allocate (set to 1) the bits of these
2201 * words.
2202 */
2203 nwords = rembits >> L2DBWORD;
2204 memset(&dp->wmap[word], (int) ONES, nwords * 4);
2205
2206 /* determine how many bits.
2207 */
2208 nb = nwords << L2DBWORD;
2209
2210 /* now update the appropriate leaves to reflect
2211 * the allocated words.
2212 */
2213 for (; nwords > 0; nwords -= nw) {
2214 if (leaf[word] < BUDMIN) {
2215 jfs_error(bmp->db_ipbmap->i_sb,
2216 "leaf page corrupt\n");
2217 break;
2218 }
2219
2220 /* determine what the leaf value should be
2221 * updated to as the minimum of the l2 number
2222 * of bits being allocated and the l2 number
2223 * of bits currently described by this leaf.
2224 */
2225 size = min_t(int, leaf[word],
2226 NLSTOL2BSZ(nwords));
2227
2228 /* update the leaf to reflect the allocation.
2229 * in addition to setting the leaf value to
2230 * NOFREE, dbSplit() will split the binary
2231 * system of the leaves to reflect the current
2232 * allocation (size).
2233 */
2234 dbSplit(tp, word, size, NOFREE, false);
2235
2236 /* get the number of dmap words handled */
2237 nw = BUDSIZE(size, BUDMIN);
2238 word += nw;
2239 }
2240 }
2241 }
2242
2243 /* update the free count for this dmap */
2244 le32_add_cpu(&dp->nfree, -nblocks);
2245
2246 BMAP_LOCK(bmp);
2247
2248 /* if this allocation group is completely free,
2249 * update the maximum allocation group number if this allocation
2250 * group is the new max.
2251 */
2252 agno = blkno >> bmp->db_agl2size;
2253 if (agno > bmp->db_maxag)
2254 bmp->db_maxag = agno;
2255
2256 /* update the free count for the allocation group and map */
2257 bmp->db_agfree[agno] -= nblocks;
2258 bmp->db_nfree -= nblocks;
2259
2260 BMAP_UNLOCK(bmp);
2261 }
2262
2263
2264 /*
2265 * NAME: dbFreeBits()
2266 *
2267 * FUNCTION: free a specified block range from a dmap.
2268 *
2269 * this routine updates the dmap to reflect the working
2270 * state allocation of the specified block range. it directly
2271 * updates the bits of the working map and causes the adjustment
2272 * of the binary buddy system described by the dmap's dmtree
2273 * leaves to reflect the bits freed. it also causes the dmap's
2274 * dmtree, as a whole, to reflect the deallocated range.
2275 *
2276 * PARAMETERS:
2277 * bmp - pointer to bmap descriptor
2278 * dp - pointer to dmap to free bits from.
2279 * blkno - starting block number of the bits to be freed.
2280 * nblocks - number of bits to be freed.
2281 *
2282 * RETURN VALUES: 0 for success
2283 *
2284 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2285 */
2286 static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2287 int nblocks)
2288 {
2289 int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2290 dmtree_t *tp = (dmtree_t *) & dp->tree;
2291 int rc = 0;
2292 int size;
2293
2294 /* determine the bit number and word within the dmap of the
2295 * starting block.
2296 */
2297 dbitno = blkno & (BPERDMAP - 1);
2298 word = dbitno >> L2DBWORD;
2299
2300 /* block range better be within the dmap.
2301 */
2302 assert(dbitno + nblocks <= BPERDMAP);
2303
2304 /* free the bits of the dmaps words corresponding to the block range.
2305 * not all bits of the first and last words may be contained within
2306 * the block range. if this is the case, we'll work against those
2307 * words (i.e. partial first and/or last) on an individual basis
2308 * (a single pass), freeing the bits of interest by hand and updating
2309 * the leaf corresponding to the dmap word. a single pass will be used
2310 * for all dmap words fully contained within the specified range.
2311 * within this pass, the bits of all fully contained dmap words will
2312 * be marked as free in a single shot and the leaves will be updated. a
2313 * single leaf may describe the free space of multiple dmap words,
2314 * so we may update only a subset of the actual leaves corresponding
2315 * to the dmap words of the block range.
2316 *
2317 * dbJoin() is used to update leaf values and will join the binary
2318 * buddy system of the leaves if the new leaf values indicate this
2319 * should be done.
2320 */
2321 for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2322 /* determine the bit number within the word and
2323 * the number of bits within the word.
2324 */
2325 wbitno = dbitno & (DBWORD - 1);
2326 nb = min(rembits, DBWORD - wbitno);
2327
2328 /* check if only part of a word is to be freed.
2329 */
2330 if (nb < DBWORD) {
2331 /* free (zero) the appropriate bits within this
2332 * dmap word.
2333 */
2334 dp->wmap[word] &=
2335 cpu_to_le32(~(ONES << (DBWORD - nb)
2336 >> wbitno));
2337
2338 /* update the leaf for this dmap word.
2339 */
2340 rc = dbJoin(tp, word,
2341 dbMaxBud((u8 *)&dp->wmap[word]), false);
2342 if (rc)
2343 return rc;
2344
2345 word += 1;
2346 } else {
2347 /* one or more dmap words are fully contained
2348 * within the block range. determine how many
2349 * words and free (zero) the bits of these words.
2350 */
2351 nwords = rembits >> L2DBWORD;
2352 memset(&dp->wmap[word], 0, nwords * 4);
2353
2354 /* determine how many bits.
2355 */
2356 nb = nwords << L2DBWORD;
2357
2358 /* now update the appropriate leaves to reflect
2359 * the freed words.
2360 */
2361 for (; nwords > 0; nwords -= nw) {
2362 /* determine what the leaf value should be
2363 * updated to as the minimum of the l2 number
2364 * of bits being freed and the l2 (max) number
2365 * of bits that can be described by this leaf.
2366 */
2367 size =
2368 min(LITOL2BSZ
2369 (word, L2LPERDMAP, BUDMIN),
2370 NLSTOL2BSZ(nwords));
2371
2372 /* update the leaf.
2373 */
2374 rc = dbJoin(tp, word, size, false);
2375 if (rc)
2376 return rc;
2377
2378 /* get the number of dmap words handled.
2379 */
2380 nw = BUDSIZE(size, BUDMIN);
2381 word += nw;
2382 }
2383 }
2384 }
2385
2386 /* update the free count for this dmap.
2387 */
2388 le32_add_cpu(&dp->nfree, nblocks);
2389
2390 BMAP_LOCK(bmp);
2391
2392 /* update the free count for the allocation group and
2393 * map.
2394 */
2395 agno = blkno >> bmp->db_agl2size;
2396 bmp->db_nfree += nblocks;
2397 bmp->db_agfree[agno] += nblocks;
2398
2399 /* check if this allocation group is not completely free and
2400 * if it is currently the maximum (rightmost) allocation group.
2401 * if so, establish the new maximum allocation group number by
2402 * searching left for the first allocation group with allocation.
2403 */
2404 if ((bmp->db_agfree[agno] == bmp->db_agsize && agno == bmp->db_maxag) ||
2405 (agno == bmp->db_numag - 1 &&
2406 bmp->db_agfree[agno] == (bmp-> db_mapsize & (BPERDMAP - 1)))) {
2407 while (bmp->db_maxag > 0) {
2408 bmp->db_maxag -= 1;
2409 if (bmp->db_agfree[bmp->db_maxag] !=
2410 bmp->db_agsize)
2411 break;
2412 }
2413
2414 /* re-establish the allocation group preference if the
2415 * current preference is right of the maximum allocation
2416 * group.
2417 */
2418 if (bmp->db_agpref > bmp->db_maxag)
2419 bmp->db_agpref = bmp->db_maxag;
2420 }
2421
2422 BMAP_UNLOCK(bmp);
2423
2424 return 0;
2425 }
2426
2427
2428 /*
2429 * NAME: dbAdjCtl()
2430 *
2431 * FUNCTION: adjust a dmap control page at a specified level to reflect
2432 * the change in a lower level dmap or dmap control page's
2433 * maximum string of free blocks (i.e. a change in the root
2434 * of the lower level object's dmtree) due to the allocation
2435 * or deallocation of a range of blocks with a single dmap.
2436 *
2437 * on entry, this routine is provided with the new value of
2438 * the lower level dmap or dmap control page root and the
2439 * starting block number of the block range whose allocation
2440 * or deallocation resulted in the root change. this range
2441 * is respresented by a single leaf of the current dmapctl
2442 * and the leaf will be updated with this value, possibly
2443 * causing a binary buddy system within the leaves to be
2444 * split or joined. the update may also cause the dmapctl's
2445 * dmtree to be updated.
2446 *
2447 * if the adjustment of the dmap control page, itself, causes its
2448 * root to change, this change will be bubbled up to the next dmap
2449 * control level by a recursive call to this routine, specifying
2450 * the new root value and the next dmap control page level to
2451 * be adjusted.
2452 * PARAMETERS:
2453 * bmp - pointer to bmap descriptor
2454 * blkno - the first block of a block range within a dmap. it is
2455 * the allocation or deallocation of this block range that
2456 * requires the dmap control page to be adjusted.
2457 * newval - the new value of the lower level dmap or dmap control
2458 * page root.
2459 * alloc - 'true' if adjustment is due to an allocation.
2460 * level - current level of dmap control page (i.e. L0, L1, L2) to
2461 * be adjusted.
2462 *
2463 * RETURN VALUES:
2464 * 0 - success
2465 * -EIO - i/o error
2466 *
2467 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2468 */
2469 static int
2470 dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
2471 {
2472 struct metapage *mp;
2473 s8 oldroot;
2474 int oldval;
2475 s64 lblkno;
2476 struct dmapctl *dcp;
2477 int rc, leafno, ti;
2478
2479 /* get the buffer for the dmap control page for the specified
2480 * block number and control page level.
2481 */
2482 lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, level);
2483 mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
2484 if (mp == NULL)
2485 return -EIO;
2486 dcp = (struct dmapctl *) mp->data;
2487
2488 if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
2489 jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page\n");
2490 release_metapage(mp);
2491 return -EIO;
2492 }
2493
2494 /* determine the leaf number corresponding to the block and
2495 * the index within the dmap control tree.
2496 */
2497 leafno = BLKTOCTLLEAF(blkno, dcp->budmin);
2498 ti = leafno + le32_to_cpu(dcp->leafidx);
2499
2500 /* save the current leaf value and the current root level (i.e.
2501 * maximum l2 free string described by this dmapctl).
2502 */
2503 oldval = dcp->stree[ti];
2504 oldroot = dcp->stree[ROOT];
2505
2506 /* check if this is a control page update for an allocation.
2507 * if so, update the leaf to reflect the new leaf value using
2508 * dbSplit(); otherwise (deallocation), use dbJoin() to update
2509 * the leaf with the new value. in addition to updating the
2510 * leaf, dbSplit() will also split the binary buddy system of
2511 * the leaves, if required, and bubble new values within the
2512 * dmapctl tree, if required. similarly, dbJoin() will join
2513 * the binary buddy system of leaves and bubble new values up
2514 * the dmapctl tree as required by the new leaf value.
2515 */
2516 if (alloc) {
2517 /* check if we are in the middle of a binary buddy
2518 * system. this happens when we are performing the
2519 * first allocation out of an allocation group that
2520 * is part (not the first part) of a larger binary
2521 * buddy system. if we are in the middle, back split
2522 * the system prior to calling dbSplit() which assumes
2523 * that it is at the front of a binary buddy system.
2524 */
2525 if (oldval == NOFREE) {
2526 rc = dbBackSplit((dmtree_t *)dcp, leafno, true);
2527 if (rc) {
2528 release_metapage(mp);
2529 return rc;
2530 }
2531 oldval = dcp->stree[ti];
2532 }
2533 dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval, true);
2534 } else {
2535 rc = dbJoin((dmtree_t *) dcp, leafno, newval, true);
2536 if (rc) {
2537 release_metapage(mp);
2538 return rc;
2539 }
2540 }
2541
2542 /* check if the root of the current dmap control page changed due
2543 * to the update and if the current dmap control page is not at
2544 * the current top level (i.e. L0, L1, L2) of the map. if so (i.e.
2545 * root changed and this is not the top level), call this routine
2546 * again (recursion) for the next higher level of the mapping to
2547 * reflect the change in root for the current dmap control page.
2548 */
2549 if (dcp->stree[ROOT] != oldroot) {
2550 /* are we below the top level of the map. if so,
2551 * bubble the root up to the next higher level.
2552 */
2553 if (level < bmp->db_maxlevel) {
2554 /* bubble up the new root of this dmap control page to
2555 * the next level.
2556 */
2557 if ((rc =
2558 dbAdjCtl(bmp, blkno, dcp->stree[ROOT], alloc,
2559 level + 1))) {
2560 /* something went wrong in bubbling up the new
2561 * root value, so backout the changes to the
2562 * current dmap control page.
2563 */
2564 if (alloc) {
2565 dbJoin((dmtree_t *) dcp, leafno,
2566 oldval, true);
2567 } else {
2568 /* the dbJoin() above might have
2569 * caused a larger binary buddy system
2570 * to form and we may now be in the
2571 * middle of it. if this is the case,
2572 * back split the buddies.
2573 */
2574 if (dcp->stree[ti] == NOFREE)
2575 dbBackSplit((dmtree_t *)
2576 dcp, leafno, true);
2577 dbSplit((dmtree_t *) dcp, leafno,
2578 dcp->budmin, oldval, true);
2579 }
2580
2581 /* release the buffer and return the error.
2582 */
2583 release_metapage(mp);
2584 return (rc);
2585 }
2586 } else {
2587 /* we're at the top level of the map. update
2588 * the bmap control page to reflect the size
2589 * of the maximum free buddy system.
2590 */
2591 assert(level == bmp->db_maxlevel);
2592 if (bmp->db_maxfreebud != oldroot) {
2593 jfs_error(bmp->db_ipbmap->i_sb,
2594 "the maximum free buddy is not the old root\n");
2595 }
2596 bmp->db_maxfreebud = dcp->stree[ROOT];
2597 }
2598 }
2599
2600 /* write the buffer.
2601 */
2602 write_metapage(mp);
2603
2604 return (0);
2605 }
2606
2607
2608 /*
2609 * NAME: dbSplit()
2610 *
2611 * FUNCTION: update the leaf of a dmtree with a new value, splitting
2612 * the leaf from the binary buddy system of the dmtree's
2613 * leaves, as required.
2614 *
2615 * PARAMETERS:
2616 * tp - pointer to the tree containing the leaf.
2617 * leafno - the number of the leaf to be updated.
2618 * splitsz - the size the binary buddy system starting at the leaf
2619 * must be split to, specified as the log2 number of blocks.
2620 * newval - the new value for the leaf.
2621 *
2622 * RETURN VALUES: none
2623 *
2624 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2625 */
2626 static void dbSplit(dmtree_t *tp, int leafno, int splitsz, int newval, bool is_ctl)
2627 {
2628 int budsz;
2629 int cursz;
2630 s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2631
2632 /* check if the leaf needs to be split.
2633 */
2634 if (leaf[leafno] > tp->dmt_budmin) {
2635 /* the split occurs by cutting the buddy system in half
2636 * at the specified leaf until we reach the specified
2637 * size. pick up the starting split size (current size
2638 * - 1 in l2) and the corresponding buddy size.
2639 */
2640 cursz = leaf[leafno] - 1;
2641 budsz = BUDSIZE(cursz, tp->dmt_budmin);
2642
2643 /* split until we reach the specified size.
2644 */
2645 while (cursz >= splitsz) {
2646 /* update the buddy's leaf with its new value.
2647 */
2648 dbAdjTree(tp, leafno ^ budsz, cursz, is_ctl);
2649
2650 /* on to the next size and buddy.
2651 */
2652 cursz -= 1;
2653 budsz >>= 1;
2654 }
2655 }
2656
2657 /* adjust the dmap tree to reflect the specified leaf's new
2658 * value.
2659 */
2660 dbAdjTree(tp, leafno, newval, is_ctl);
2661 }
2662
2663
2664 /*
2665 * NAME: dbBackSplit()
2666 *
2667 * FUNCTION: back split the binary buddy system of dmtree leaves
2668 * that hold a specified leaf until the specified leaf
2669 * starts its own binary buddy system.
2670 *
2671 * the allocators typically perform allocations at the start
2672 * of binary buddy systems and dbSplit() is used to accomplish
2673 * any required splits. in some cases, however, allocation
2674 * may occur in the middle of a binary system and requires a
2675 * back split, with the split proceeding out from the middle of
2676 * the system (less efficient) rather than the start of the
2677 * system (more efficient). the cases in which a back split
2678 * is required are rare and are limited to the first allocation
2679 * within an allocation group which is a part (not first part)
2680 * of a larger binary buddy system and a few exception cases
2681 * in which a previous join operation must be backed out.
2682 *
2683 * PARAMETERS:
2684 * tp - pointer to the tree containing the leaf.
2685 * leafno - the number of the leaf to be updated.
2686 *
2687 * RETURN VALUES: none
2688 *
2689 * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2690 */
2691 static int dbBackSplit(dmtree_t *tp, int leafno, bool is_ctl)
2692 {
2693 int budsz, bud, w, bsz, size;
2694 int cursz;
2695 s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2696
2697 /* leaf should be part (not first part) of a binary
2698 * buddy system.
2699 */
2700 assert(leaf[leafno] == NOFREE);
2701
2702 /* the back split is accomplished by iteratively finding the leaf
2703 * that starts the buddy system that contains the specified leaf and
2704 * splitting that system in two. this iteration continues until
2705 * the specified leaf becomes the start of a buddy system.
2706 *
2707 * determine maximum possible l2 size for the specified leaf.
2708 */
2709 size =
2710 LITOL2BSZ(leafno, le32_to_cpu(tp->dmt_l2nleafs),
2711 tp->dmt_budmin);
2712
2713 /* determine the number of leaves covered by this size. this
2714 * is the buddy size that we will start with as we search for
2715 * the buddy system that contains the specified leaf.
2716 */
2717 budsz = BUDSIZE(size, tp->dmt_budmin);
2718
2719 /* back split.
2720 */
2721 while (leaf[leafno] == NOFREE) {
2722 /* find the leftmost buddy leaf.
2723 */
2724 for (w = leafno, bsz = budsz;; bsz <<= 1,
2725 w = (w < bud) ? w : bud) {
2726 if (bsz >= le32_to_cpu(tp->dmt_nleafs)) {
2727 jfs_err("JFS: block map error in dbBackSplit");
2728 return -EIO;
2729 }
2730
2731 /* determine the buddy.
2732 */
2733 bud = w ^ bsz;
2734
2735 /* check if this buddy is the start of the system.
2736 */
2737 if (leaf[bud] != NOFREE) {
2738 /* split the leaf at the start of the
2739 * system in two.
2740 */
2741 cursz = leaf[bud] - 1;
2742 dbSplit(tp, bud, cursz, cursz, is_ctl);
2743 break;
2744 }
2745 }
2746 }
2747
2748 if (leaf[leafno] != size) {
2749 jfs_err("JFS: wrong leaf value in dbBackSplit");
2750 return -EIO;
2751 }
2752 return 0;
2753 }
2754
2755
2756 /*
2757 * NAME: dbJoin()
2758 *
2759 * FUNCTION: update the leaf of a dmtree with a new value, joining
2760 * the leaf with other leaves of the dmtree into a multi-leaf
2761 * binary buddy system, as required.
2762 *
2763 * PARAMETERS:
2764 * tp - pointer to the tree containing the leaf.
2765 * leafno - the number of the leaf to be updated.
2766 * newval - the new value for the leaf.
2767 *
2768 * RETURN VALUES: none
2769 */
2770 static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl)
2771 {
2772 int budsz, buddy;
2773 s8 *leaf;
2774
2775 /* can the new leaf value require a join with other leaves ?
2776 */
2777 if (newval >= tp->dmt_budmin) {
2778 /* pickup a pointer to the leaves of the tree.
2779 */
2780 leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2781
2782 /* try to join the specified leaf into a large binary
2783 * buddy system. the join proceeds by attempting to join
2784 * the specified leafno with its buddy (leaf) at new value.
2785 * if the join occurs, we attempt to join the left leaf
2786 * of the joined buddies with its buddy at new value + 1.
2787 * we continue to join until we find a buddy that cannot be
2788 * joined (does not have a value equal to the size of the
2789 * last join) or until all leaves have been joined into a
2790 * single system.
2791 *
2792 * get the buddy size (number of words covered) of
2793 * the new value.
2794 */
2795 budsz = BUDSIZE(newval, tp->dmt_budmin);
2796
2797 /* try to join.
2798 */
2799 while (budsz < le32_to_cpu(tp->dmt_nleafs)) {
2800 /* get the buddy leaf.
2801 */
2802 buddy = leafno ^ budsz;
2803
2804 /* if the leaf's new value is greater than its
2805 * buddy's value, we join no more.
2806 */
2807 if (newval > leaf[buddy])
2808 break;
2809
2810 /* It shouldn't be less */
2811 if (newval < leaf[buddy])
2812 return -EIO;
2813
2814 /* check which (leafno or buddy) is the left buddy.
2815 * the left buddy gets to claim the blocks resulting
2816 * from the join while the right gets to claim none.
2817 * the left buddy is also eligible to participate in
2818 * a join at the next higher level while the right
2819 * is not.
2820 *
2821 */
2822 if (leafno < buddy) {
2823 /* leafno is the left buddy.
2824 */
2825 dbAdjTree(tp, buddy, NOFREE, is_ctl);
2826 } else {
2827 /* buddy is the left buddy and becomes
2828 * leafno.
2829 */
2830 dbAdjTree(tp, leafno, NOFREE, is_ctl);
2831 leafno = buddy;
2832 }
2833
2834 /* on to try the next join.
2835 */
2836 newval += 1;
2837 budsz <<= 1;
2838 }
2839 }
2840
2841 /* update the leaf value.
2842 */
2843 dbAdjTree(tp, leafno, newval, is_ctl);
2844
2845 return 0;
2846 }
2847
2848
2849 /*
2850 * NAME: dbAdjTree()
2851 *
2852 * FUNCTION: update a leaf of a dmtree with a new value, adjusting
2853 * the dmtree, as required, to reflect the new leaf value.
2854 * the combination of any buddies must already be done before
2855 * this is called.
2856 *
2857 * PARAMETERS:
2858 * tp - pointer to the tree to be adjusted.
2859 * leafno - the number of the leaf to be updated.
2860 * newval - the new value for the leaf.
2861 *
2862 * RETURN VALUES: none
2863 */
2864 static void dbAdjTree(dmtree_t *tp, int leafno, int newval, bool is_ctl)
2865 {
2866 int lp, pp, k;
2867 int max, size;
2868
2869 size = is_ctl ? CTLTREESIZE : TREESIZE;
2870
2871 /* pick up the index of the leaf for this leafno.
2872 */
2873 lp = leafno + le32_to_cpu(tp->dmt_leafidx);
2874
2875 if (WARN_ON_ONCE(lp >= size || lp < 0))
2876 return;
2877
2878 /* is the current value the same as the old value ? if so,
2879 * there is nothing to do.
2880 */
2881 if (tp->dmt_stree[lp] == newval)
2882 return;
2883
2884 /* set the new value.
2885 */
2886 tp->dmt_stree[lp] = newval;
2887
2888 /* bubble the new value up the tree as required.
2889 */
2890 for (k = 0; k < le32_to_cpu(tp->dmt_height); k++) {
2891 /* get the index of the first leaf of the 4 leaf
2892 * group containing the specified leaf (leafno).
2893 */
2894 lp = ((lp - 1) & ~0x03) + 1;
2895
2896 /* get the index of the parent of this 4 leaf group.
2897 */
2898 pp = (lp - 1) >> 2;
2899
2900 /* determine the maximum of the 4 leaves.
2901 */
2902 max = TREEMAX(&tp->dmt_stree[lp]);
2903
2904 /* if the maximum of the 4 is the same as the
2905 * parent's value, we're done.
2906 */
2907 if (tp->dmt_stree[pp] == max)
2908 break;
2909
2910 /* parent gets new value.
2911 */
2912 tp->dmt_stree[pp] = max;
2913
2914 /* parent becomes leaf for next go-round.
2915 */
2916 lp = pp;
2917 }
2918 }
2919
2920
2921 /*
2922 * NAME: dbFindLeaf()
2923 *
2924 * FUNCTION: search a dmtree_t for sufficient free blocks, returning
2925 * the index of a leaf describing the free blocks if
2926 * sufficient free blocks are found.
2927 *
2928 * the search starts at the top of the dmtree_t tree and
2929 * proceeds down the tree to the leftmost leaf with sufficient
2930 * free space.
2931 *
2932 * PARAMETERS:
2933 * tp - pointer to the tree to be searched.
2934 * l2nb - log2 number of free blocks to search for.
2935 * leafidx - return pointer to be set to the index of the leaf
2936 * describing at least l2nb free blocks if sufficient
2937 * free blocks are found.
2938 * is_ctl - determines if the tree is of type ctl
2939 *
2940 * RETURN VALUES:
2941 * 0 - success
2942 * -ENOSPC - insufficient free blocks.
2943 */
2944 static int dbFindLeaf(dmtree_t *tp, int l2nb, int *leafidx, bool is_ctl)
2945 {
2946 int ti, n = 0, k, x = 0;
2947 int max_size, max_idx;
2948
2949 max_size = is_ctl ? CTLTREESIZE : TREESIZE;
2950 max_idx = is_ctl ? LPERCTL : LPERDMAP;
2951
2952 /* first check the root of the tree to see if there is
2953 * sufficient free space.
2954 */
2955 if (l2nb > tp->dmt_stree[ROOT])
2956 return -ENOSPC;
2957
2958 /* sufficient free space available. now search down the tree
2959 * starting at the next level for the leftmost leaf that
2960 * describes sufficient free space.
2961 */
2962 for (k = le32_to_cpu(tp->dmt_height), ti = 1;
2963 k > 0; k--, ti = ((ti + n) << 2) + 1) {
2964 /* search the four nodes at this level, starting from
2965 * the left.
2966 */
2967 for (x = ti, n = 0; n < 4; n++) {
2968 /* sufficient free space found. move to the next
2969 * level (or quit if this is the last level).
2970 */
2971 if (x + n > max_size)
2972 return -ENOSPC;
2973 if (l2nb <= tp->dmt_stree[x + n])
2974 break;
2975 }
2976
2977 /* better have found something since the higher
2978 * levels of the tree said it was here.
2979 */
2980 assert(n < 4);
2981 }
2982 if (le32_to_cpu(tp->dmt_leafidx) >= max_idx)
2983 return -ENOSPC;
2984
2985 /* set the return to the leftmost leaf describing sufficient
2986 * free space.
2987 */
2988 *leafidx = x + n - le32_to_cpu(tp->dmt_leafidx);
2989
2990 return (0);
2991 }
2992
2993
2994 /*
2995 * NAME: dbFindBits()
2996 *
2997 * FUNCTION: find a specified number of binary buddy free bits within a
2998 * dmap bitmap word value.
2999 *
3000 * this routine searches the bitmap value for (1 << l2nb) free
3001 * bits at (1 << l2nb) alignments within the value.
3002 *
3003 * PARAMETERS:
3004 * word - dmap bitmap word value.
3005 * l2nb - number of free bits specified as a log2 number.
3006 *
3007 * RETURN VALUES:
3008 * starting bit number of free bits.
3009 */
3010 static int dbFindBits(u32 word, int l2nb)
3011 {
3012 int bitno, nb;
3013 u32 mask;
3014
3015 /* get the number of bits.
3016 */
3017 nb = 1 << l2nb;
3018 assert(nb <= DBWORD);
3019
3020 /* complement the word so we can use a mask (i.e. 0s represent
3021 * free bits) and compute the mask.
3022 */
3023 word = ~word;
3024 mask = ONES << (DBWORD - nb);
3025
3026 /* scan the word for nb free bits at nb alignments.
3027 */
3028 for (bitno = 0; mask != 0; bitno += nb, mask = (mask >> nb)) {
3029 if ((mask & word) == mask)
3030 break;
3031 }
3032
3033 ASSERT(bitno < 32);
3034
3035 /* return the bit number.
3036 */
3037 return (bitno);
3038 }
3039
3040
3041 /*
3042 * NAME: dbMaxBud(u8 *cp)
3043 *
3044 * FUNCTION: determine the largest binary buddy string of free
3045 * bits within 32-bits of the map.
3046 *
3047 * PARAMETERS:
3048 * cp - pointer to the 32-bit value.
3049 *
3050 * RETURN VALUES:
3051 * largest binary buddy of free bits within a dmap word.
3052 */
3053 static int dbMaxBud(u8 * cp)
3054 {
3055 signed char tmp1, tmp2;
3056
3057 /* check if the wmap word is all free. if so, the
3058 * free buddy size is BUDMIN.
3059 */
3060 if (*((uint *) cp) == 0)
3061 return (BUDMIN);
3062
3063 /* check if the wmap word is half free. if so, the
3064 * free buddy size is BUDMIN-1.
3065 */
3066 if (*((u16 *) cp) == 0 || *((u16 *) cp + 1) == 0)
3067 return (BUDMIN - 1);
3068
3069 /* not all free or half free. determine the free buddy
3070 * size thru table lookup using quarters of the wmap word.
3071 */
3072 tmp1 = max(budtab[cp[2]], budtab[cp[3]]);
3073 tmp2 = max(budtab[cp[0]], budtab[cp[1]]);
3074 return (max(tmp1, tmp2));
3075 }
3076
3077
3078 /*
3079 * NAME: cnttz(uint word)
3080 *
3081 * FUNCTION: determine the number of trailing zeros within a 32-bit
3082 * value.
3083 *
3084 * PARAMETERS:
3085 * value - 32-bit value to be examined.
3086 *
3087 * RETURN VALUES:
3088 * count of trailing zeros
3089 */
3090 static int cnttz(u32 word)
3091 {
3092 int n;
3093
3094 for (n = 0; n < 32; n++, word >>= 1) {
3095 if (word & 0x01)
3096 break;
3097 }
3098
3099 return (n);
3100 }
3101
3102
3103 /*
3104 * NAME: cntlz(u32 value)
3105 *
3106 * FUNCTION: determine the number of leading zeros within a 32-bit
3107 * value.
3108 *
3109 * PARAMETERS:
3110 * value - 32-bit value to be examined.
3111 *
3112 * RETURN VALUES:
3113 * count of leading zeros
3114 */
3115 static int cntlz(u32 value)
3116 {
3117 int n;
3118
3119 for (n = 0; n < 32; n++, value <<= 1) {
3120 if (value & HIGHORDER)
3121 break;
3122 }
3123 return (n);
3124 }
3125
3126
3127 /*
3128 * NAME: blkstol2(s64 nb)
3129 *
3130 * FUNCTION: convert a block count to its log2 value. if the block
3131 * count is not a l2 multiple, it is rounded up to the next
3132 * larger l2 multiple.
3133 *
3134 * PARAMETERS:
3135 * nb - number of blocks
3136 *
3137 * RETURN VALUES:
3138 * log2 number of blocks
3139 */
3140 static int blkstol2(s64 nb)
3141 {
3142 int l2nb;
3143 s64 mask; /* meant to be signed */
3144
3145 mask = (s64) 1 << (64 - 1);
3146
3147 /* count the leading bits.
3148 */
3149 for (l2nb = 0; l2nb < 64; l2nb++, mask >>= 1) {
3150 /* leading bit found.
3151 */
3152 if (nb & mask) {
3153 /* determine the l2 value.
3154 */
3155 l2nb = (64 - 1) - l2nb;
3156
3157 /* check if we need to round up.
3158 */
3159 if (~mask & nb)
3160 l2nb++;
3161
3162 return (l2nb);
3163 }
3164 }
3165 assert(0);
3166 return 0; /* fix compiler warning */
3167 }
3168
3169
3170 /*
3171 * NAME: dbAllocBottomUp()
3172 *
3173 * FUNCTION: alloc the specified block range from the working block
3174 * allocation map.
3175 *
3176 * the blocks will be alloc from the working map one dmap
3177 * at a time.
3178 *
3179 * PARAMETERS:
3180 * ip - pointer to in-core inode;
3181 * blkno - starting block number to be freed.
3182 * nblocks - number of blocks to be freed.
3183 *
3184 * RETURN VALUES:
3185 * 0 - success
3186 * -EIO - i/o error
3187 */
3188 int dbAllocBottomUp(struct inode *ip, s64 blkno, s64 nblocks)
3189 {
3190 struct metapage *mp;
3191 struct dmap *dp;
3192 int nb, rc;
3193 s64 lblkno, rem;
3194 struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
3195 struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
3196
3197 IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
3198
3199 /* block to be allocated better be within the mapsize. */
3200 ASSERT(nblocks <= bmp->db_mapsize - blkno);
3201
3202 /*
3203 * allocate the blocks a dmap at a time.
3204 */
3205 mp = NULL;
3206 for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
3207 /* release previous dmap if any */
3208 if (mp) {
3209 write_metapage(mp);
3210 }
3211
3212 /* get the buffer for the current dmap. */
3213 lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
3214 mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
3215 if (mp == NULL) {
3216 IREAD_UNLOCK(ipbmap);
3217 return -EIO;
3218 }
3219 dp = (struct dmap *) mp->data;
3220
3221 /* determine the number of blocks to be allocated from
3222 * this dmap.
3223 */
3224 nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
3225
3226 /* allocate the blocks. */
3227 if ((rc = dbAllocDmapBU(bmp, dp, blkno, nb))) {
3228 release_metapage(mp);
3229 IREAD_UNLOCK(ipbmap);
3230 return (rc);
3231 }
3232 }
3233
3234 /* write the last buffer. */
3235 write_metapage(mp);
3236
3237 IREAD_UNLOCK(ipbmap);
3238
3239 return (0);
3240 }
3241
3242
3243 static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
3244 int nblocks)
3245 {
3246 int rc;
3247 int dbitno, word, rembits, nb, nwords, wbitno, agno;
3248 s8 oldroot;
3249 struct dmaptree *tp = (struct dmaptree *) & dp->tree;
3250
3251 /* save the current value of the root (i.e. maximum free string)
3252 * of the dmap tree.
3253 */
3254 oldroot = tp->stree[ROOT];
3255
3256 /* determine the bit number and word within the dmap of the
3257 * starting block.
3258 */
3259 dbitno = blkno & (BPERDMAP - 1);
3260 word = dbitno >> L2DBWORD;
3261
3262 /* block range better be within the dmap */
3263 assert(dbitno + nblocks <= BPERDMAP);
3264
3265 /* allocate the bits of the dmap's words corresponding to the block
3266 * range. not all bits of the first and last words may be contained
3267 * within the block range. if this is the case, we'll work against
3268 * those words (i.e. partial first and/or last) on an individual basis
3269 * (a single pass), allocating the bits of interest by hand and
3270 * updating the leaf corresponding to the dmap word. a single pass
3271 * will be used for all dmap words fully contained within the
3272 * specified range. within this pass, the bits of all fully contained
3273 * dmap words will be marked as free in a single shot and the leaves
3274 * will be updated. a single leaf may describe the free space of
3275 * multiple dmap words, so we may update only a subset of the actual
3276 * leaves corresponding to the dmap words of the block range.
3277 */
3278 for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
3279 /* determine the bit number within the word and
3280 * the number of bits within the word.
3281 */
3282 wbitno = dbitno & (DBWORD - 1);
3283 nb = min(rembits, DBWORD - wbitno);
3284
3285 /* check if only part of a word is to be allocated.
3286 */
3287 if (nb < DBWORD) {
3288 /* allocate (set to 1) the appropriate bits within
3289 * this dmap word.
3290 */
3291 dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
3292 >> wbitno);
3293
3294 word++;
3295 } else {
3296 /* one or more dmap words are fully contained
3297 * within the block range. determine how many
3298 * words and allocate (set to 1) the bits of these
3299 * words.
3300 */
3301 nwords = rembits >> L2DBWORD;
3302 memset(&dp->wmap[word], (int) ONES, nwords * 4);
3303
3304 /* determine how many bits */
3305 nb = nwords << L2DBWORD;
3306 word += nwords;
3307 }
3308 }
3309
3310 /* update the free count for this dmap */
3311 le32_add_cpu(&dp->nfree, -nblocks);
3312
3313 /* reconstruct summary tree */
3314 dbInitDmapTree(dp);
3315
3316 BMAP_LOCK(bmp);
3317
3318 /* if this allocation group is completely free,
3319 * update the highest active allocation group number
3320 * if this allocation group is the new max.
3321 */
3322 agno = blkno >> bmp->db_agl2size;
3323 if (agno > bmp->db_maxag)
3324 bmp->db_maxag = agno;
3325
3326 /* update the free count for the allocation group and map */
3327 bmp->db_agfree[agno] -= nblocks;
3328 bmp->db_nfree -= nblocks;
3329
3330 BMAP_UNLOCK(bmp);
3331
3332 /* if the root has not changed, done. */
3333 if (tp->stree[ROOT] == oldroot)
3334 return (0);
3335
3336 /* root changed. bubble the change up to the dmap control pages.
3337 * if the adjustment of the upper level control pages fails,
3338 * backout the bit allocation (thus making everything consistent).
3339 */
3340 if ((rc = dbAdjCtl(bmp, blkno, tp->stree[ROOT], 1, 0)))
3341 dbFreeBits(bmp, dp, blkno, nblocks);
3342
3343 return (rc);
3344 }
3345
3346
3347 /*
3348 * NAME: dbExtendFS()
3349 *
3350 * FUNCTION: extend bmap from blkno for nblocks;
3351 * dbExtendFS() updates bmap ready for dbAllocBottomUp();
3352 *
3353 * L2
3354 * |
3355 * L1---------------------------------L1
3356 * | |
3357 * L0---------L0---------L0 L0---------L0---------L0
3358 * | | | | | |
3359 * d0,...,dn d0,...,dn d0,...,dn d0,...,dn d0,...,dn d0,.,dm;
3360 * L2L1L0d0,...,dnL0d0,...,dnL0d0,...,dnL1L0d0,...,dnL0d0,...,dnL0d0,..dm
3361 *
3362 * <---old---><----------------------------extend----------------------->
3363 */
3364 int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks)
3365 {
3366 struct jfs_sb_info *sbi = JFS_SBI(ipbmap->i_sb);
3367 int nbperpage = sbi->nbperpage;
3368 int i, i0 = true, j, j0 = true, k, n;
3369 s64 newsize;
3370 s64 p;
3371 struct metapage *mp, *l2mp, *l1mp = NULL, *l0mp = NULL;
3372 struct dmapctl *l2dcp, *l1dcp, *l0dcp;
3373 struct dmap *dp;
3374 s8 *l0leaf, *l1leaf, *l2leaf;
3375 struct bmap *bmp = sbi->bmap;
3376 int agno, l2agsize, oldl2agsize;
3377 s64 ag_rem;
3378
3379 newsize = blkno + nblocks;
3380
3381 jfs_info("dbExtendFS: blkno:%Ld nblocks:%Ld newsize:%Ld",
3382 (long long) blkno, (long long) nblocks, (long long) newsize);
3383
3384 /*
3385 * initialize bmap control page.
3386 *
3387 * all the data in bmap control page should exclude
3388 * the mkfs hidden dmap page.
3389 */
3390
3391 /* update mapsize */
3392 bmp->db_mapsize = newsize;
3393 bmp->db_maxlevel = BMAPSZTOLEV(bmp->db_mapsize);
3394
3395 /* compute new AG size */
3396 l2agsize = dbGetL2AGSize(newsize);
3397 oldl2agsize = bmp->db_agl2size;
3398
3399 bmp->db_agl2size = l2agsize;
3400 bmp->db_agsize = 1 << l2agsize;
3401
3402 /* compute new number of AG */
3403 agno = bmp->db_numag;
3404 bmp->db_numag = newsize >> l2agsize;
3405 bmp->db_numag += ((u32) newsize % (u32) bmp->db_agsize) ? 1 : 0;
3406
3407 /*
3408 * reconfigure db_agfree[]
3409 * from old AG configuration to new AG configuration;
3410 *
3411 * coalesce contiguous k (newAGSize/oldAGSize) AGs;
3412 * i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
3413 * note: new AG size = old AG size * (2**x).
3414 */
3415 if (l2agsize == oldl2agsize)
3416 goto extend;
3417 k = 1 << (l2agsize - oldl2agsize);
3418 ag_rem = bmp->db_agfree[0]; /* save agfree[0] */
3419 for (i = 0, n = 0; i < agno; n++) {
3420 bmp->db_agfree[n] = 0; /* init collection point */
3421
3422 /* coalesce contiguous k AGs; */
3423 for (j = 0; j < k && i < agno; j++, i++) {
3424 /* merge AGi to AGn */
3425 bmp->db_agfree[n] += bmp->db_agfree[i];
3426 }
3427 }
3428 bmp->db_agfree[0] += ag_rem; /* restore agfree[0] */
3429
3430 for (; n < MAXAG; n++)
3431 bmp->db_agfree[n] = 0;
3432
3433 /*
3434 * update highest active ag number
3435 */
3436
3437 bmp->db_maxag = bmp->db_maxag / k;
3438
3439 /*
3440 * extend bmap
3441 *
3442 * update bit maps and corresponding level control pages;
3443 * global control page db_nfree, db_agfree[agno], db_maxfreebud;
3444 */
3445 extend:
3446 /* get L2 page */
3447 p = BMAPBLKNO + nbperpage; /* L2 page */
3448 l2mp = read_metapage(ipbmap, p, PSIZE, 0);
3449 if (!l2mp) {
3450 jfs_error(ipbmap->i_sb, "L2 page could not be read\n");
3451 return -EIO;
3452 }
3453 l2dcp = (struct dmapctl *) l2mp->data;
3454
3455 /* compute start L1 */
3456 k = blkno >> L2MAXL1SIZE;
3457 l2leaf = l2dcp->stree + CTLLEAFIND + k;
3458 p = BLKTOL1(blkno, sbi->l2nbperpage); /* L1 page */
3459
3460 /*
3461 * extend each L1 in L2
3462 */
3463 for (; k < LPERCTL; k++, p += nbperpage) {
3464 /* get L1 page */
3465 if (j0) {
3466 /* read in L1 page: (blkno & (MAXL1SIZE - 1)) */
3467 l1mp = read_metapage(ipbmap, p, PSIZE, 0);
3468 if (l1mp == NULL)
3469 goto errout;
3470 l1dcp = (struct dmapctl *) l1mp->data;
3471
3472 /* compute start L0 */
3473 j = (blkno & (MAXL1SIZE - 1)) >> L2MAXL0SIZE;
3474 l1leaf = l1dcp->stree + CTLLEAFIND + j;
3475 p = BLKTOL0(blkno, sbi->l2nbperpage);
3476 j0 = false;
3477 } else {
3478 /* assign/init L1 page */
3479 l1mp = get_metapage(ipbmap, p, PSIZE, 0);
3480 if (l1mp == NULL)
3481 goto errout;
3482
3483 l1dcp = (struct dmapctl *) l1mp->data;
3484
3485 /* compute start L0 */
3486 j = 0;
3487 l1leaf = l1dcp->stree + CTLLEAFIND;
3488 p += nbperpage; /* 1st L0 of L1.k */
3489 }
3490
3491 /*
3492 * extend each L0 in L1
3493 */
3494 for (; j < LPERCTL; j++) {
3495 /* get L0 page */
3496 if (i0) {
3497 /* read in L0 page: (blkno & (MAXL0SIZE - 1)) */
3498
3499 l0mp = read_metapage(ipbmap, p, PSIZE, 0);
3500 if (l0mp == NULL)
3501 goto errout;
3502 l0dcp = (struct dmapctl *) l0mp->data;
3503
3504 /* compute start dmap */
3505 i = (blkno & (MAXL0SIZE - 1)) >>
3506 L2BPERDMAP;
3507 l0leaf = l0dcp->stree + CTLLEAFIND + i;
3508 p = BLKTODMAP(blkno,
3509 sbi->l2nbperpage);
3510 i0 = false;
3511 } else {
3512 /* assign/init L0 page */
3513 l0mp = get_metapage(ipbmap, p, PSIZE, 0);
3514 if (l0mp == NULL)
3515 goto errout;
3516
3517 l0dcp = (struct dmapctl *) l0mp->data;
3518
3519 /* compute start dmap */
3520 i = 0;
3521 l0leaf = l0dcp->stree + CTLLEAFIND;
3522 p += nbperpage; /* 1st dmap of L0.j */
3523 }
3524
3525 /*
3526 * extend each dmap in L0
3527 */
3528 for (; i < LPERCTL; i++) {
3529 /*
3530 * reconstruct the dmap page, and
3531 * initialize corresponding parent L0 leaf
3532 */
3533 if ((n = blkno & (BPERDMAP - 1))) {
3534 /* read in dmap page: */
3535 mp = read_metapage(ipbmap, p,
3536 PSIZE, 0);
3537 if (mp == NULL)
3538 goto errout;
3539 n = min(nblocks, (s64)BPERDMAP - n);
3540 } else {
3541 /* assign/init dmap page */
3542 mp = read_metapage(ipbmap, p,
3543 PSIZE, 0);
3544 if (mp == NULL)
3545 goto errout;
3546
3547 n = min_t(s64, nblocks, BPERDMAP);
3548 }
3549
3550 dp = (struct dmap *) mp->data;
3551 *l0leaf = dbInitDmap(dp, blkno, n);
3552
3553 bmp->db_nfree += n;
3554 agno = le64_to_cpu(dp->start) >> l2agsize;
3555 bmp->db_agfree[agno] += n;
3556
3557 write_metapage(mp);
3558
3559 l0leaf++;
3560 p += nbperpage;
3561
3562 blkno += n;
3563 nblocks -= n;
3564 if (nblocks == 0)
3565 break;
3566 } /* for each dmap in a L0 */
3567
3568 /*
3569 * build current L0 page from its leaves, and
3570 * initialize corresponding parent L1 leaf
3571 */
3572 *l1leaf = dbInitDmapCtl(l0dcp, 0, ++i);
3573 write_metapage(l0mp);
3574 l0mp = NULL;
3575
3576 if (nblocks)
3577 l1leaf++; /* continue for next L0 */
3578 else {
3579 /* more than 1 L0 ? */
3580 if (j > 0)
3581 break; /* build L1 page */
3582 else {
3583 /* summarize in global bmap page */
3584 bmp->db_maxfreebud = *l1leaf;
3585 release_metapage(l1mp);
3586 release_metapage(l2mp);
3587 goto finalize;
3588 }
3589 }
3590 } /* for each L0 in a L1 */
3591
3592 /*
3593 * build current L1 page from its leaves, and
3594 * initialize corresponding parent L2 leaf
3595 */
3596 *l2leaf = dbInitDmapCtl(l1dcp, 1, ++j);
3597 write_metapage(l1mp);
3598 l1mp = NULL;
3599
3600 if (nblocks)
3601 l2leaf++; /* continue for next L1 */
3602 else {
3603 /* more than 1 L1 ? */
3604 if (k > 0)
3605 break; /* build L2 page */
3606 else {
3607 /* summarize in global bmap page */
3608 bmp->db_maxfreebud = *l2leaf;
3609 release_metapage(l2mp);
3610 goto finalize;
3611 }
3612 }
3613 } /* for each L1 in a L2 */
3614
3615 jfs_error(ipbmap->i_sb, "function has not returned as expected\n");
3616 errout:
3617 if (l0mp)
3618 release_metapage(l0mp);
3619 if (l1mp)
3620 release_metapage(l1mp);
3621 release_metapage(l2mp);
3622 return -EIO;
3623
3624 /*
3625 * finalize bmap control page
3626 */
3627 finalize:
3628
3629 return 0;
3630 }
3631
3632
3633 /*
3634 * dbFinalizeBmap()
3635 */
3636 void dbFinalizeBmap(struct inode *ipbmap)
3637 {
3638 struct bmap *bmp = JFS_SBI(ipbmap->i_sb)->bmap;
3639 int actags, inactags, l2nl;
3640 s64 ag_rem, actfree, inactfree, avgfree;
3641 int i, n;
3642
3643 /*
3644 * finalize bmap control page
3645 */
3646 //finalize:
3647 /*
3648 * compute db_agpref: preferred ag to allocate from
3649 * (the leftmost ag with average free space in it);
3650 */
3651 //agpref:
3652 /* get the number of active ags and inactive ags */
3653 actags = bmp->db_maxag + 1;
3654 inactags = bmp->db_numag - actags;
3655 ag_rem = bmp->db_mapsize & (bmp->db_agsize - 1); /* ??? */
3656
3657 /* determine how many blocks are in the inactive allocation
3658 * groups. in doing this, we must account for the fact that
3659 * the rightmost group might be a partial group (i.e. file
3660 * system size is not a multiple of the group size).
3661 */
3662 inactfree = (inactags && ag_rem) ?
3663 ((inactags - 1) << bmp->db_agl2size) + ag_rem
3664 : inactags << bmp->db_agl2size;
3665
3666 /* determine how many free blocks are in the active
3667 * allocation groups plus the average number of free blocks
3668 * within the active ags.
3669 */
3670 actfree = bmp->db_nfree - inactfree;
3671 avgfree = (u32) actfree / (u32) actags;
3672
3673 /* if the preferred allocation group has not average free space.
3674 * re-establish the preferred group as the leftmost
3675 * group with average free space.
3676 */
3677 if (bmp->db_agfree[bmp->db_agpref] < avgfree) {
3678 for (bmp->db_agpref = 0; bmp->db_agpref < actags;
3679 bmp->db_agpref++) {
3680 if (bmp->db_agfree[bmp->db_agpref] >= avgfree)
3681 break;
3682 }
3683 if (bmp->db_agpref >= bmp->db_numag) {
3684 jfs_error(ipbmap->i_sb,
3685 "cannot find ag with average freespace\n");
3686 }
3687 }
3688
3689 /*
3690 * compute db_aglevel, db_agheight, db_width, db_agstart:
3691 * an ag is covered in aglevel dmapctl summary tree,
3692 * at agheight level height (from leaf) with agwidth number of nodes
3693 * each, which starts at agstart index node of the smmary tree node
3694 * array;
3695 */
3696 bmp->db_aglevel = BMAPSZTOLEV(bmp->db_agsize);
3697 l2nl =
3698 bmp->db_agl2size - (L2BPERDMAP + bmp->db_aglevel * L2LPERCTL);
3699 bmp->db_agheight = l2nl >> 1;
3700 bmp->db_agwidth = 1 << (l2nl - (bmp->db_agheight << 1));
3701 for (i = 5 - bmp->db_agheight, bmp->db_agstart = 0, n = 1; i > 0;
3702 i--) {
3703 bmp->db_agstart += n;
3704 n <<= 2;
3705 }
3706
3707 }
3708
3709
3710 /*
3711 * NAME: dbInitDmap()/ujfs_idmap_page()
3712 *
3713 * FUNCTION: initialize working/persistent bitmap of the dmap page
3714 * for the specified number of blocks:
3715 *
3716 * at entry, the bitmaps had been initialized as free (ZEROS);
3717 * The number of blocks will only account for the actually
3718 * existing blocks. Blocks which don't actually exist in
3719 * the aggregate will be marked as allocated (ONES);
3720 *
3721 * PARAMETERS:
3722 * dp - pointer to page of map
3723 * nblocks - number of blocks this page
3724 *
3725 * RETURNS: NONE
3726 */
3727 static int dbInitDmap(struct dmap * dp, s64 Blkno, int nblocks)
3728 {
3729 int blkno, w, b, r, nw, nb, i;
3730
3731 /* starting block number within the dmap */
3732 blkno = Blkno & (BPERDMAP - 1);
3733
3734 if (blkno == 0) {
3735 dp->nblocks = dp->nfree = cpu_to_le32(nblocks);
3736 dp->start = cpu_to_le64(Blkno);
3737
3738 if (nblocks == BPERDMAP) {
3739 memset(&dp->wmap[0], 0, LPERDMAP * 4);
3740 memset(&dp->pmap[0], 0, LPERDMAP * 4);
3741 goto initTree;
3742 }
3743 } else {
3744 le32_add_cpu(&dp->nblocks, nblocks);
3745 le32_add_cpu(&dp->nfree, nblocks);
3746 }
3747
3748 /* word number containing start block number */
3749 w = blkno >> L2DBWORD;
3750
3751 /*
3752 * free the bits corresponding to the block range (ZEROS):
3753 * note: not all bits of the first and last words may be contained
3754 * within the block range.
3755 */
3756 for (r = nblocks; r > 0; r -= nb, blkno += nb) {
3757 /* number of bits preceding range to be freed in the word */
3758 b = blkno & (DBWORD - 1);
3759 /* number of bits to free in the word */
3760 nb = min(r, DBWORD - b);
3761
3762 /* is partial word to be freed ? */
3763 if (nb < DBWORD) {
3764 /* free (set to 0) from the bitmap word */
3765 dp->wmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3766 >> b));
3767 dp->pmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3768 >> b));
3769
3770 /* skip the word freed */
3771 w++;
3772 } else {
3773 /* free (set to 0) contiguous bitmap words */
3774 nw = r >> L2DBWORD;
3775 memset(&dp->wmap[w], 0, nw * 4);
3776 memset(&dp->pmap[w], 0, nw * 4);
3777
3778 /* skip the words freed */
3779 nb = nw << L2DBWORD;
3780 w += nw;
3781 }
3782 }
3783
3784 /*
3785 * mark bits following the range to be freed (non-existing
3786 * blocks) as allocated (ONES)
3787 */
3788
3789 if (blkno == BPERDMAP)
3790 goto initTree;
3791
3792 /* the first word beyond the end of existing blocks */
3793 w = blkno >> L2DBWORD;
3794
3795 /* does nblocks fall on a 32-bit boundary ? */
3796 b = blkno & (DBWORD - 1);
3797 if (b) {
3798 /* mark a partial word allocated */
3799 dp->wmap[w] = dp->pmap[w] = cpu_to_le32(ONES >> b);
3800 w++;
3801 }
3802
3803 /* set the rest of the words in the page to allocated (ONES) */
3804 for (i = w; i < LPERDMAP; i++)
3805 dp->pmap[i] = dp->wmap[i] = cpu_to_le32(ONES);
3806
3807 /*
3808 * init tree
3809 */
3810 initTree:
3811 return (dbInitDmapTree(dp));
3812 }
3813
3814
3815 /*
3816 * NAME: dbInitDmapTree()/ujfs_complete_dmap()
3817 *
3818 * FUNCTION: initialize summary tree of the specified dmap:
3819 *
3820 * at entry, bitmap of the dmap has been initialized;
3821 *
3822 * PARAMETERS:
3823 * dp - dmap to complete
3824 * blkno - starting block number for this dmap
3825 * treemax - will be filled in with max free for this dmap
3826 *
3827 * RETURNS: max free string at the root of the tree
3828 */
3829 static int dbInitDmapTree(struct dmap * dp)
3830 {
3831 struct dmaptree *tp;
3832 s8 *cp;
3833 int i;
3834
3835 /* init fixed info of tree */
3836 tp = &dp->tree;
3837 tp->nleafs = cpu_to_le32(LPERDMAP);
3838 tp->l2nleafs = cpu_to_le32(L2LPERDMAP);
3839 tp->leafidx = cpu_to_le32(LEAFIND);
3840 tp->height = cpu_to_le32(4);
3841 tp->budmin = BUDMIN;
3842
3843 /* init each leaf from corresponding wmap word:
3844 * note: leaf is set to NOFREE(-1) if all blocks of corresponding
3845 * bitmap word are allocated.
3846 */
3847 cp = tp->stree + le32_to_cpu(tp->leafidx);
3848 for (i = 0; i < LPERDMAP; i++)
3849 *cp++ = dbMaxBud((u8 *) & dp->wmap[i]);
3850
3851 /* build the dmap's binary buddy summary tree */
3852 return (dbInitTree(tp));
3853 }
3854
3855
3856 /*
3857 * NAME: dbInitTree()/ujfs_adjtree()
3858 *
3859 * FUNCTION: initialize binary buddy summary tree of a dmap or dmapctl.
3860 *
3861 * at entry, the leaves of the tree has been initialized
3862 * from corresponding bitmap word or root of summary tree
3863 * of the child control page;
3864 * configure binary buddy system at the leaf level, then
3865 * bubble up the values of the leaf nodes up the tree.
3866 *
3867 * PARAMETERS:
3868 * cp - Pointer to the root of the tree
3869 * l2leaves- Number of leaf nodes as a power of 2
3870 * l2min - Number of blocks that can be covered by a leaf
3871 * as a power of 2
3872 *
3873 * RETURNS: max free string at the root of the tree
3874 */
3875 static int dbInitTree(struct dmaptree * dtp)
3876 {
3877 int l2max, l2free, bsize, nextb, i;
3878 int child, parent, nparent;
3879 s8 *tp, *cp, *cp1;
3880
3881 tp = dtp->stree;
3882
3883 /* Determine the maximum free string possible for the leaves */
3884 l2max = le32_to_cpu(dtp->l2nleafs) + dtp->budmin;
3885
3886 /*
3887 * configure the leaf level into binary buddy system
3888 *
3889 * Try to combine buddies starting with a buddy size of 1
3890 * (i.e. two leaves). At a buddy size of 1 two buddy leaves
3891 * can be combined if both buddies have a maximum free of l2min;
3892 * the combination will result in the left-most buddy leaf having
3893 * a maximum free of l2min+1.
3894 * After processing all buddies for a given size, process buddies
3895 * at the next higher buddy size (i.e. current size * 2) and
3896 * the next maximum free (current free + 1).
3897 * This continues until the maximum possible buddy combination
3898 * yields maximum free.
3899 */
3900 for (l2free = dtp->budmin, bsize = 1; l2free < l2max;
3901 l2free++, bsize = nextb) {
3902 /* get next buddy size == current buddy pair size */
3903 nextb = bsize << 1;
3904
3905 /* scan each adjacent buddy pair at current buddy size */
3906 for (i = 0, cp = tp + le32_to_cpu(dtp->leafidx);
3907 i < le32_to_cpu(dtp->nleafs);
3908 i += nextb, cp += nextb) {
3909 /* coalesce if both adjacent buddies are max free */
3910 if (*cp == l2free && *(cp + bsize) == l2free) {
3911 *cp = l2free + 1; /* left take right */
3912 *(cp + bsize) = -1; /* right give left */
3913 }
3914 }
3915 }
3916
3917 /*
3918 * bubble summary information of leaves up the tree.
3919 *
3920 * Starting at the leaf node level, the four nodes described by
3921 * the higher level parent node are compared for a maximum free and
3922 * this maximum becomes the value of the parent node.
3923 * when all lower level nodes are processed in this fashion then
3924 * move up to the next level (parent becomes a lower level node) and
3925 * continue the process for that level.
3926 */
3927 for (child = le32_to_cpu(dtp->leafidx),
3928 nparent = le32_to_cpu(dtp->nleafs) >> 2;
3929 nparent > 0; nparent >>= 2, child = parent) {
3930 /* get index of 1st node of parent level */
3931 parent = (child - 1) >> 2;
3932
3933 /* set the value of the parent node as the maximum
3934 * of the four nodes of the current level.
3935 */
3936 for (i = 0, cp = tp + child, cp1 = tp + parent;
3937 i < nparent; i++, cp += 4, cp1++)
3938 *cp1 = TREEMAX(cp);
3939 }
3940
3941 return (*tp);
3942 }
3943
3944
3945 /*
3946 * dbInitDmapCtl()
3947 *
3948 * function: initialize dmapctl page
3949 */
3950 static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i)
3951 { /* start leaf index not covered by range */
3952 s8 *cp;
3953
3954 dcp->nleafs = cpu_to_le32(LPERCTL);
3955 dcp->l2nleafs = cpu_to_le32(L2LPERCTL);
3956 dcp->leafidx = cpu_to_le32(CTLLEAFIND);
3957 dcp->height = cpu_to_le32(5);
3958 dcp->budmin = L2BPERDMAP + L2LPERCTL * level;
3959
3960 /*
3961 * initialize the leaves of current level that were not covered
3962 * by the specified input block range (i.e. the leaves have no
3963 * low level dmapctl or dmap).
3964 */
3965 cp = &dcp->stree[CTLLEAFIND + i];
3966 for (; i < LPERCTL; i++)
3967 *cp++ = NOFREE;
3968
3969 /* build the dmap's binary buddy summary tree */
3970 return (dbInitTree((struct dmaptree *) dcp));
3971 }
3972
3973
3974 /*
3975 * NAME: dbGetL2AGSize()/ujfs_getagl2size()
3976 *
3977 * FUNCTION: Determine log2(allocation group size) from aggregate size
3978 *
3979 * PARAMETERS:
3980 * nblocks - Number of blocks in aggregate
3981 *
3982 * RETURNS: log2(allocation group size) in aggregate blocks
3983 */
3984 static int dbGetL2AGSize(s64 nblocks)
3985 {
3986 s64 sz;
3987 s64 m;
3988 int l2sz;
3989
3990 if (nblocks < BPERDMAP * MAXAG)
3991 return (L2BPERDMAP);
3992
3993 /* round up aggregate size to power of 2 */
3994 m = ((u64) 1 << (64 - 1));
3995 for (l2sz = 64; l2sz >= 0; l2sz--, m >>= 1) {
3996 if (m & nblocks)
3997 break;
3998 }
3999
4000 sz = (s64) 1 << l2sz;
4001 if (sz < nblocks)
4002 l2sz += 1;
4003
4004 /* agsize = roundupSize/max_number_of_ag */
4005 return (l2sz - L2MAXAG);
4006 }
4007
4008
4009 /*
4010 * NAME: dbMapFileSizeToMapSize()
4011 *
4012 * FUNCTION: compute number of blocks the block allocation map file
4013 * can cover from the map file size;
4014 *
4015 * RETURNS: Number of blocks which can be covered by this block map file;
4016 */
4017
4018 /*
4019 * maximum number of map pages at each level including control pages
4020 */
4021 #define MAXL0PAGES (1 + LPERCTL)
4022 #define MAXL1PAGES (1 + LPERCTL * MAXL0PAGES)
4023
4024 /*
4025 * convert number of map pages to the zero origin top dmapctl level
4026 */
4027 #define BMAPPGTOLEV(npages) \
4028 (((npages) <= 3 + MAXL0PAGES) ? 0 : \
4029 ((npages) <= 2 + MAXL1PAGES) ? 1 : 2)
4030
4031 s64 dbMapFileSizeToMapSize(struct inode * ipbmap)
4032 {
4033 struct super_block *sb = ipbmap->i_sb;
4034 s64 nblocks;
4035 s64 npages, ndmaps;
4036 int level, i;
4037 int complete, factor;
4038
4039 nblocks = ipbmap->i_size >> JFS_SBI(sb)->l2bsize;
4040 npages = nblocks >> JFS_SBI(sb)->l2nbperpage;
4041 level = BMAPPGTOLEV(npages);
4042
4043 /* At each level, accumulate the number of dmap pages covered by
4044 * the number of full child levels below it;
4045 * repeat for the last incomplete child level.
4046 */
4047 ndmaps = 0;
4048 npages--; /* skip the first global control page */
4049 /* skip higher level control pages above top level covered by map */
4050 npages -= (2 - level);
4051 npages--; /* skip top level's control page */
4052 for (i = level; i >= 0; i--) {
4053 factor =
4054 (i == 2) ? MAXL1PAGES : ((i == 1) ? MAXL0PAGES : 1);
4055 complete = (u32) npages / factor;
4056 ndmaps += complete * ((i == 2) ? LPERCTL * LPERCTL :
4057 ((i == 1) ? LPERCTL : 1));
4058
4059 /* pages in last/incomplete child */
4060 npages = (u32) npages % factor;
4061 /* skip incomplete child's level control page */
4062 npages--;
4063 }
4064
4065 /* convert the number of dmaps into the number of blocks
4066 * which can be covered by the dmaps;
4067 */
4068 nblocks = ndmaps << L2BPERDMAP;
4069
4070 return (nblocks);
4071 }
4072
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