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);
67	static int dbBackSplit(dmtree_t * tp, int leafno);
68	static int dbJoin(dmtree_t * tp, int leafno, int newval);
69	static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
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(size: 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) {
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(sb: 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(objp: 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(sb: ipbmap->i_sb)->bmap;
268
269	if (!(mounterror || isReadOnly(inode: 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(objp: bmp);
279	JFS_SBI(sb: 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(sb: 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(mapping: 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(sb: ip->i_sb)->ipbmap;
362	struct bmap *bmp = JFS_SBI(sb: 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(ip: 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, nblocks: 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(sb: 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(sb: 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(list: &mp->synclist, head: &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(new: &mp->synclist, head: &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(sb: 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(v: &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(v: &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(sb: 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(sb: 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(v: &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, nblocks: (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(v: &bmp->db_active[agno]);
828	if ((writers > 1) ||
829	((writers == 1) && (JFS_IP(inode: 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, nblocks: (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, nblocks: (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, hint: blkno + nblocks - 1, nblocks: 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(sb: 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, blkno: extblkno, nblocks: (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, level: bmp->db_aglevel - 1,
1465	blkno: &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, level: bmp->db_maxlevel, blkno: &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(sb: ip->i_sb)->ipbmap;
1579	struct bmap *bmp = JFS_SBI(sb: 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(n: range_cnt, size: 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, results: &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	nblocks = 1LL << l2nb;
1630	} else {
1631	/* Trim any already allocated blocks */
1632	jfs_error(bmp->db_ipbmap->i_sb, "-EIO\n");
1633	break;
1634	}
1635
1636	/* check, if our trim array is full */
1637	if (unlikely(count >= range_cnt - 1))
1638	break;
1639	}
1640	IWRITE_UNLOCK(ipbmap);
1641
1642	tt->nblocks = 0; /* mark the current end */
1643	for (tt = totrim; tt->nblocks != 0; tt++) {
1644	/* when mounted with online discard, dbFree() will
1645	* call jfs_issue_discard() itself */
1646	if (!(JFS_SBI(sb)->flag & JFS_DISCARD))
1647	jfs_issue_discard(ip, blkno: tt->blkno, nblocks: tt->nblocks);
1648	dbFree(ip, blkno: tt->blkno, nblocks: tt->nblocks);
1649	trimmed += tt->nblocks;
1650	}
1651	kfree(objp: totrim);
1652
1653	return trimmed;
1654	}
1655
1656	/*
1657	* NAME: dbFindCtl()
1658	*
1659	* FUNCTION: starting at a specified dmap control page level and block
1660	* number, search down the dmap control levels for a range of
1661	* contiguous free blocks large enough to satisfy an allocation
1662	* request for the specified number of free blocks.
1663	*
1664	* if sufficient contiguous free blocks are found, this routine
1665	* returns the starting block number within a dmap page that
1666	* contains or starts a range of contiqious free blocks that
1667	* is sufficient in size.
1668	*
1669	* PARAMETERS:
1670	* bmp - pointer to bmap descriptor
1671	* level - starting dmap control page level.
1672	* l2nb - log2 number of contiguous free blocks desired.
1673	* *blkno - on entry, starting block number for conducting the search.
1674	* on successful return, the first block within a dmap page
1675	* that contains or starts a range of contiguous free blocks.
1676	*
1677	* RETURN VALUES:
1678	* 0 - success
1679	* -ENOSPC - insufficient disk resources
1680	* -EIO - i/o error
1681	*
1682	* serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1683	*/
1684	static int dbFindCtl(struct bmap * bmp, int l2nb, int level, s64 * blkno)
1685	{
1686	int rc, leafidx, lev;
1687	s64 b, lblkno;
1688	struct dmapctl *dcp;
1689	int budmin;
1690	struct metapage *mp;
1691
1692	/* starting at the specified dmap control page level and block
1693	* number, search down the dmap control levels for the starting
1694	* block number of a dmap page that contains or starts off
1695	* sufficient free blocks.
1696	*/
1697	for (lev = level, b = *blkno; lev >= 0; lev--) {
1698	/* get the buffer of the dmap control page for the block
1699	* number and level (i.e. L0, L1, L2).
1700	*/
1701	lblkno = BLKTOCTL(b, bmp->db_l2nbperpage, lev);
1702	mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1703	if (mp == NULL)
1704	return -EIO;
1705	dcp = (struct dmapctl *) mp->data;
1706	budmin = dcp->budmin;
1707
1708	if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
1709	jfs_error(bmp->db_ipbmap->i_sb,
1710	"Corrupt dmapctl page\n");
1711	release_metapage(mp);
1712	return -EIO;
1713	}
1714
1715	/* search the tree within the dmap control page for
1716	* sufficient free space. if sufficient free space is found,
1717	* dbFindLeaf() returns the index of the leaf at which
1718	* free space was found.
1719	*/
1720	rc = dbFindLeaf(tp: (dmtree_t *) dcp, l2nb, leafidx: &leafidx, is_ctl: true);
1721
1722	/* release the buffer.
1723	*/
1724	release_metapage(mp);
1725
1726	/* space found ?
1727	*/
1728	if (rc) {
1729	if (lev != level) {
1730	jfs_error(bmp->db_ipbmap->i_sb,
1731	"dmap inconsistent\n");
1732	return -EIO;
1733	}
1734	return -ENOSPC;
1735	}
1736
1737	/* adjust the block number to reflect the location within
1738	* the dmap control page (i.e. the leaf) at which free
1739	* space was found.
1740	*/
1741	b += (((s64) leafidx) << budmin);
1742
1743	/* we stop the search at this dmap control page level if
1744	* the number of blocks required is greater than or equal
1745	* to the maximum number of blocks described at the next
1746	* (lower) level.
1747	*/
1748	if (l2nb >= budmin)
1749	break;
1750	}
1751
1752	*blkno = b;
1753	return (0);
1754	}
1755
1756
1757	/*
1758	* NAME: dbAllocCtl()
1759	*
1760	* FUNCTION: attempt to allocate a specified number of contiguous
1761	* blocks starting within a specific dmap.
1762	*
1763	* this routine is called by higher level routines that search
1764	* the dmap control pages above the actual dmaps for contiguous
1765	* free space. the result of successful searches by these
1766	* routines are the starting block numbers within dmaps, with
1767	* the dmaps themselves containing the desired contiguous free
1768	* space or starting a contiguous free space of desired size
1769	* that is made up of the blocks of one or more dmaps. these
1770	* calls should not fail due to insufficent resources.
1771	*
1772	* this routine is called in some cases where it is not known
1773	* whether it will fail due to insufficient resources. more
1774	* specifically, this occurs when allocating from an allocation
1775	* group whose size is equal to the number of blocks per dmap.
1776	* in this case, the dmap control pages are not examined prior
1777	* to calling this routine (to save pathlength) and the call
1778	* might fail.
1779	*
1780	* for a request size that fits within a dmap, this routine relies
1781	* upon the dmap's dmtree to find the requested contiguous free
1782	* space. for request sizes that are larger than a dmap, the
1783	* requested free space will start at the first block of the
1784	* first dmap (i.e. blkno).
1785	*
1786	* PARAMETERS:
1787	* bmp - pointer to bmap descriptor
1788	* nblocks - actual number of contiguous free blocks to allocate.
1789	* l2nb - log2 number of contiguous free blocks to allocate.
1790	* blkno - starting block number of the dmap to start the allocation
1791	* from.
1792	* results - on successful return, set to the starting block number
1793	* of the newly allocated range.
1794	*
1795	* RETURN VALUES:
1796	* 0 - success
1797	* -ENOSPC - insufficient disk resources
1798	* -EIO - i/o error
1799	*
1800	* serialization: IWRITE_LOCK(ipbmap) held on entry/exit;
1801	*/
1802	static int
1803	dbAllocCtl(struct bmap * bmp, s64 nblocks, int l2nb, s64 blkno, s64 * results)
1804	{
1805	int rc, nb;
1806	s64 b, lblkno, n;
1807	struct metapage *mp;
1808	struct dmap *dp;
1809
1810	/* check if the allocation request is confined to a single dmap.
1811	*/
1812	if (l2nb <= L2BPERDMAP) {
1813	/* get the buffer for the dmap.
1814	*/
1815	lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
1816	mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1817	if (mp == NULL)
1818	return -EIO;
1819	dp = (struct dmap *) mp->data;
1820
1821	/* try to allocate the blocks.
1822	*/
1823	rc = dbAllocDmapLev(bmp, dp, nblocks: (int) nblocks, l2nb, results);
1824	if (rc == 0)
1825	mark_metapage_dirty(mp);
1826
1827	release_metapage(mp);
1828
1829	return (rc);
1830	}
1831
1832	/* allocation request involving multiple dmaps. it must start on
1833	* a dmap boundary.
1834	*/
1835	assert((blkno & (BPERDMAP - 1)) == 0);
1836
1837	/* allocate the blocks dmap by dmap.
1838	*/
1839	for (n = nblocks, b = blkno; n > 0; n -= nb, b += nb) {
1840	/* get the buffer for the dmap.
1841	*/
1842	lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1843	mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1844	if (mp == NULL) {
1845	rc = -EIO;
1846	goto backout;
1847	}
1848	dp = (struct dmap *) mp->data;
1849
1850	/* the dmap better be all free.
1851	*/
1852	if (dp->tree.stree[ROOT] != L2BPERDMAP) {
1853	release_metapage(mp);
1854	jfs_error(bmp->db_ipbmap->i_sb,
1855	"the dmap is not all free\n");
1856	rc = -EIO;
1857	goto backout;
1858	}
1859
1860	/* determine how many blocks to allocate from this dmap.
1861	*/
1862	nb = min_t(s64, n, BPERDMAP);
1863
1864	/* allocate the blocks from the dmap.
1865	*/
1866	if ((rc = dbAllocDmap(bmp, dp, blkno: b, nblocks: nb))) {
1867	release_metapage(mp);
1868	goto backout;
1869	}
1870
1871	/* write the buffer.
1872	*/
1873	write_metapage(mp);
1874	}
1875
1876	/* set the results (starting block number) and return.
1877	*/
1878	*results = blkno;
1879	return (0);
1880
1881	/* something failed in handling an allocation request involving
1882	* multiple dmaps. we'll try to clean up by backing out any
1883	* allocation that has already happened for this request. if
1884	* we fail in backing out the allocation, we'll mark the file
1885	* system to indicate that blocks have been leaked.
1886	*/
1887	backout:
1888
1889	/* try to backout the allocations dmap by dmap.
1890	*/
1891	for (n = nblocks - n, b = blkno; n > 0;
1892	n -= BPERDMAP, b += BPERDMAP) {
1893	/* get the buffer for this dmap.
1894	*/
1895	lblkno = BLKTODMAP(b, bmp->db_l2nbperpage);
1896	mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
1897	if (mp == NULL) {
1898	/* could not back out. mark the file system
1899	* to indicate that we have leaked blocks.
1900	*/
1901	jfs_error(bmp->db_ipbmap->i_sb,
1902	"I/O Error: Block Leakage\n");
1903	continue;
1904	}
1905	dp = (struct dmap *) mp->data;
1906
1907	/* free the blocks is this dmap.
1908	*/
1909	if (dbFreeDmap(bmp, dp, blkno: b, BPERDMAP)) {
1910	/* could not back out. mark the file system
1911	* to indicate that we have leaked blocks.
1912	*/
1913	release_metapage(mp);
1914	jfs_error(bmp->db_ipbmap->i_sb, "Block Leakage\n");
1915	continue;
1916	}
1917
1918	/* write the buffer.
1919	*/
1920	write_metapage(mp);
1921	}
1922
1923	return (rc);
1924	}
1925
1926
1927	/*
1928	* NAME: dbAllocDmapLev()
1929	*
1930	* FUNCTION: attempt to allocate a specified number of contiguous blocks
1931	* from a specified dmap.
1932	*
1933	* this routine checks if the contiguous blocks are available.
1934	* if so, nblocks of blocks are allocated; otherwise, ENOSPC is
1935	* returned.
1936	*
1937	* PARAMETERS:
1938	* mp - pointer to bmap descriptor
1939	* dp - pointer to dmap to attempt to allocate blocks from.
1940	* l2nb - log2 number of contiguous block desired.
1941	* nblocks - actual number of contiguous block desired.
1942	* results - on successful return, set to the starting block number
1943	* of the newly allocated range.
1944	*
1945	* RETURN VALUES:
1946	* 0 - success
1947	* -ENOSPC - insufficient disk resources
1948	* -EIO - i/o error
1949	*
1950	* serialization: IREAD_LOCK(ipbmap), e.g., from dbAlloc(), or
1951	* IWRITE_LOCK(ipbmap), e.g., dbAllocCtl(), held on entry/exit;
1952	*/
1953	static int
1954	dbAllocDmapLev(struct bmap * bmp,
1955	struct dmap * dp, int nblocks, int l2nb, s64 * results)
1956	{
1957	s64 blkno;
1958	int leafidx, rc;
1959
1960	/* can't be more than a dmaps worth of blocks */
1961	assert(l2nb <= L2BPERDMAP);
1962
1963	/* search the tree within the dmap page for sufficient
1964	* free space. if sufficient free space is found, dbFindLeaf()
1965	* returns the index of the leaf at which free space was found.
1966	*/
1967	if (dbFindLeaf(tp: (dmtree_t *) &dp->tree, l2nb, leafidx: &leafidx, is_ctl: false))
1968	return -ENOSPC;
1969
1970	if (leafidx < 0)
1971	return -EIO;
1972
1973	/* determine the block number within the file system corresponding
1974	* to the leaf at which free space was found.
1975	*/
1976	blkno = le64_to_cpu(dp->start) + (leafidx << L2DBWORD);
1977
1978	/* if not all bits of the dmap word are free, get the starting
1979	* bit number within the dmap word of the required string of free
1980	* bits and adjust the block number with this value.
1981	*/
1982	if (dp->tree.stree[leafidx + LEAFIND] < BUDMIN)
1983	blkno += dbFindBits(le32_to_cpu(dp->wmap[leafidx]), l2nb);
1984
1985	/* allocate the blocks */
1986	if ((rc = dbAllocDmap(bmp, dp, blkno, nblocks)) == 0)
1987	*results = blkno;
1988
1989	return (rc);
1990	}
1991
1992
1993	/*
1994	* NAME: dbAllocDmap()
1995	*
1996	* FUNCTION: adjust the disk allocation map to reflect the allocation
1997	* of a specified block range within a dmap.
1998	*
1999	* this routine allocates the specified blocks from the dmap
2000	* through a call to dbAllocBits(). if the allocation of the
2001	* block range causes the maximum string of free blocks within
2002	* the dmap to change (i.e. the value of the root of the dmap's
2003	* dmtree), this routine will cause this change to be reflected
2004	* up through the appropriate levels of the dmap control pages
2005	* by a call to dbAdjCtl() for the L0 dmap control page that
2006	* covers this dmap.
2007	*
2008	* PARAMETERS:
2009	* bmp - pointer to bmap descriptor
2010	* dp - pointer to dmap to allocate the block range from.
2011	* blkno - starting block number of the block to be allocated.
2012	* nblocks - number of blocks to be allocated.
2013	*
2014	* RETURN VALUES:
2015	* 0 - success
2016	* -EIO - i/o error
2017	*
2018	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2019	*/
2020	static int dbAllocDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2021	int nblocks)
2022	{
2023	s8 oldroot;
2024	int rc;
2025
2026	/* save the current value of the root (i.e. maximum free string)
2027	* of the dmap tree.
2028	*/
2029	oldroot = dp->tree.stree[ROOT];
2030
2031	/* allocate the specified (blocks) bits */
2032	dbAllocBits(bmp, dp, blkno, nblocks);
2033
2034	/* if the root has not changed, done. */
2035	if (dp->tree.stree[ROOT] == oldroot)
2036	return (0);
2037
2038	/* root changed. bubble the change up to the dmap control pages.
2039	* if the adjustment of the upper level control pages fails,
2040	* backout the bit allocation (thus making everything consistent).
2041	*/
2042	if ((rc = dbAdjCtl(bmp, blkno, newval: dp->tree.stree[ROOT], alloc: 1, level: 0)))
2043	dbFreeBits(bmp, dp, blkno, nblocks);
2044
2045	return (rc);
2046	}
2047
2048
2049	/*
2050	* NAME: dbFreeDmap()
2051	*
2052	* FUNCTION: adjust the disk allocation map to reflect the allocation
2053	* of a specified block range within a dmap.
2054	*
2055	* this routine frees the specified blocks from the dmap through
2056	* a call to dbFreeBits(). if the deallocation of the block range
2057	* causes the maximum string of free blocks within the dmap to
2058	* change (i.e. the value of the root of the dmap's dmtree), this
2059	* routine will cause this change to be reflected up through the
2060	* appropriate levels of the dmap control pages by a call to
2061	* dbAdjCtl() for the L0 dmap control page that covers this dmap.
2062	*
2063	* PARAMETERS:
2064	* bmp - pointer to bmap descriptor
2065	* dp - pointer to dmap to free the block range from.
2066	* blkno - starting block number of the block to be freed.
2067	* nblocks - number of blocks to be freed.
2068	*
2069	* RETURN VALUES:
2070	* 0 - success
2071	* -EIO - i/o error
2072	*
2073	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2074	*/
2075	static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
2076	int nblocks)
2077	{
2078	s8 oldroot;
2079	int rc = 0, word;
2080
2081	/* save the current value of the root (i.e. maximum free string)
2082	* of the dmap tree.
2083	*/
2084	oldroot = dp->tree.stree[ROOT];
2085
2086	/* free the specified (blocks) bits */
2087	rc = dbFreeBits(bmp, dp, blkno, nblocks);
2088
2089	/* if error or the root has not changed, done. */
2090	if (rc || (dp->tree.stree[ROOT] == oldroot))
2091	return (rc);
2092
2093	/* root changed. bubble the change up to the dmap control pages.
2094	* if the adjustment of the upper level control pages fails,
2095	* backout the deallocation.
2096	*/
2097	if ((rc = dbAdjCtl(bmp, blkno, newval: dp->tree.stree[ROOT], alloc: 0, level: 0))) {
2098	word = (blkno & (BPERDMAP - 1)) >> L2DBWORD;
2099
2100	/* as part of backing out the deallocation, we will have
2101	* to back split the dmap tree if the deallocation caused
2102	* the freed blocks to become part of a larger binary buddy
2103	* system.
2104	*/
2105	if (dp->tree.stree[word] == NOFREE)
2106	dbBackSplit(tp: (dmtree_t *) & dp->tree, leafno: word);
2107
2108	dbAllocBits(bmp, dp, blkno, nblocks);
2109	}
2110
2111	return (rc);
2112	}
2113
2114
2115	/*
2116	* NAME: dbAllocBits()
2117	*
2118	* FUNCTION: allocate a specified block range from a dmap.
2119	*
2120	* this routine updates the dmap to reflect the working
2121	* state allocation of the specified block range. it directly
2122	* updates the bits of the working map and causes the adjustment
2123	* of the binary buddy system described by the dmap's dmtree
2124	* leaves to reflect the bits allocated. it also causes the
2125	* dmap's dmtree, as a whole, to reflect the allocated range.
2126	*
2127	* PARAMETERS:
2128	* bmp - pointer to bmap descriptor
2129	* dp - pointer to dmap to allocate bits from.
2130	* blkno - starting block number of the bits to be allocated.
2131	* nblocks - number of bits to be allocated.
2132	*
2133	* RETURN VALUES: none
2134	*
2135	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2136	*/
2137	static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2138	int nblocks)
2139	{
2140	int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2141	dmtree_t *tp = (dmtree_t *) & dp->tree;
2142	int size;
2143	s8 *leaf;
2144
2145	/* pick up a pointer to the leaves of the dmap tree */
2146	leaf = dp->tree.stree + LEAFIND;
2147
2148	/* determine the bit number and word within the dmap of the
2149	* starting block.
2150	*/
2151	dbitno = blkno & (BPERDMAP - 1);
2152	word = dbitno >> L2DBWORD;
2153
2154	/* block range better be within the dmap */
2155	assert(dbitno + nblocks <= BPERDMAP);
2156
2157	/* allocate the bits of the dmap's words corresponding to the block
2158	* range. not all bits of the first and last words may be contained
2159	* within the block range. if this is the case, we'll work against
2160	* those words (i.e. partial first and/or last) on an individual basis
2161	* (a single pass), allocating the bits of interest by hand and
2162	* updating the leaf corresponding to the dmap word. a single pass
2163	* will be used for all dmap words fully contained within the
2164	* specified range. within this pass, the bits of all fully contained
2165	* dmap words will be marked as free in a single shot and the leaves
2166	* will be updated. a single leaf may describe the free space of
2167	* multiple dmap words, so we may update only a subset of the actual
2168	* leaves corresponding to the dmap words of the block range.
2169	*/
2170	for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2171	/* determine the bit number within the word and
2172	* the number of bits within the word.
2173	*/
2174	wbitno = dbitno & (DBWORD - 1);
2175	nb = min(rembits, DBWORD - wbitno);
2176
2177	/* check if only part of a word is to be allocated.
2178	*/
2179	if (nb < DBWORD) {
2180	/* allocate (set to 1) the appropriate bits within
2181	* this dmap word.
2182	*/
2183	dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
2184	>> wbitno);
2185
2186	/* update the leaf for this dmap word. in addition
2187	* to setting the leaf value to the binary buddy max
2188	* of the updated dmap word, dbSplit() will split
2189	* the binary system of the leaves if need be.
2190	*/
2191	dbSplit(tp, leafno: word, BUDMIN,
2192	newval: dbMaxBud(cp: (u8 *) & dp->wmap[word]));
2193
2194	word += 1;
2195	} else {
2196	/* one or more dmap words are fully contained
2197	* within the block range. determine how many
2198	* words and allocate (set to 1) the bits of these
2199	* words.
2200	*/
2201	nwords = rembits >> L2DBWORD;
2202	memset(&dp->wmap[word], (int) ONES, nwords * 4);
2203
2204	/* determine how many bits.
2205	*/
2206	nb = nwords << L2DBWORD;
2207
2208	/* now update the appropriate leaves to reflect
2209	* the allocated words.
2210	*/
2211	for (; nwords > 0; nwords -= nw) {
2212	if (leaf[word] < BUDMIN) {
2213	jfs_error(bmp->db_ipbmap->i_sb,
2214	"leaf page corrupt\n");
2215	break;
2216	}
2217
2218	/* determine what the leaf value should be
2219	* updated to as the minimum of the l2 number
2220	* of bits being allocated and the l2 number
2221	* of bits currently described by this leaf.
2222	*/
2223	size = min_t(int, leaf[word],
2224	NLSTOL2BSZ(nwords));
2225
2226	/* update the leaf to reflect the allocation.
2227	* in addition to setting the leaf value to
2228	* NOFREE, dbSplit() will split the binary
2229	* system of the leaves to reflect the current
2230	* allocation (size).
2231	*/
2232	dbSplit(tp, leafno: word, splitsz: size, NOFREE);
2233
2234	/* get the number of dmap words handled */
2235	nw = BUDSIZE(size, BUDMIN);
2236	word += nw;
2237	}
2238	}
2239	}
2240
2241	/* update the free count for this dmap */
2242	le32_add_cpu(var: &dp->nfree, val: -nblocks);
2243
2244	BMAP_LOCK(bmp);
2245
2246	/* if this allocation group is completely free,
2247	* update the maximum allocation group number if this allocation
2248	* group is the new max.
2249	*/
2250	agno = blkno >> bmp->db_agl2size;
2251	if (agno > bmp->db_maxag)
2252	bmp->db_maxag = agno;
2253
2254	/* update the free count for the allocation group and map */
2255	bmp->db_agfree[agno] -= nblocks;
2256	bmp->db_nfree -= nblocks;
2257
2258	BMAP_UNLOCK(bmp);
2259	}
2260
2261
2262	/*
2263	* NAME: dbFreeBits()
2264	*
2265	* FUNCTION: free a specified block range from a dmap.
2266	*
2267	* this routine updates the dmap to reflect the working
2268	* state allocation of the specified block range. it directly
2269	* updates the bits of the working map and causes the adjustment
2270	* of the binary buddy system described by the dmap's dmtree
2271	* leaves to reflect the bits freed. it also causes the dmap's
2272	* dmtree, as a whole, to reflect the deallocated range.
2273	*
2274	* PARAMETERS:
2275	* bmp - pointer to bmap descriptor
2276	* dp - pointer to dmap to free bits from.
2277	* blkno - starting block number of the bits to be freed.
2278	* nblocks - number of bits to be freed.
2279	*
2280	* RETURN VALUES: 0 for success
2281	*
2282	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2283	*/
2284	static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
2285	int nblocks)
2286	{
2287	int dbitno, word, rembits, nb, nwords, wbitno, nw, agno;
2288	dmtree_t *tp = (dmtree_t *) & dp->tree;
2289	int rc = 0;
2290	int size;
2291
2292	/* determine the bit number and word within the dmap of the
2293	* starting block.
2294	*/
2295	dbitno = blkno & (BPERDMAP - 1);
2296	word = dbitno >> L2DBWORD;
2297
2298	/* block range better be within the dmap.
2299	*/
2300	assert(dbitno + nblocks <= BPERDMAP);
2301
2302	/* free the bits of the dmaps words corresponding to the block range.
2303	* not all bits of the first and last words may be contained within
2304	* the block range. if this is the case, we'll work against those
2305	* words (i.e. partial first and/or last) on an individual basis
2306	* (a single pass), freeing the bits of interest by hand and updating
2307	* the leaf corresponding to the dmap word. a single pass will be used
2308	* for all dmap words fully contained within the specified range.
2309	* within this pass, the bits of all fully contained dmap words will
2310	* be marked as free in a single shot and the leaves will be updated. a
2311	* single leaf may describe the free space of multiple dmap words,
2312	* so we may update only a subset of the actual leaves corresponding
2313	* to the dmap words of the block range.
2314	*
2315	* dbJoin() is used to update leaf values and will join the binary
2316	* buddy system of the leaves if the new leaf values indicate this
2317	* should be done.
2318	*/
2319	for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
2320	/* determine the bit number within the word and
2321	* the number of bits within the word.
2322	*/
2323	wbitno = dbitno & (DBWORD - 1);
2324	nb = min(rembits, DBWORD - wbitno);
2325
2326	/* check if only part of a word is to be freed.
2327	*/
2328	if (nb < DBWORD) {
2329	/* free (zero) the appropriate bits within this
2330	* dmap word.
2331	*/
2332	dp->wmap[word] &=
2333	cpu_to_le32(~(ONES << (DBWORD - nb)
2334	>> wbitno));
2335
2336	/* update the leaf for this dmap word.
2337	*/
2338	rc = dbJoin(tp, leafno: word,
2339	newval: dbMaxBud(cp: (u8 *) & dp->wmap[word]));
2340	if (rc)
2341	return rc;
2342
2343	word += 1;
2344	} else {
2345	/* one or more dmap words are fully contained
2346	* within the block range. determine how many
2347	* words and free (zero) the bits of these words.
2348	*/
2349	nwords = rembits >> L2DBWORD;
2350	memset(&dp->wmap[word], 0, nwords * 4);
2351
2352	/* determine how many bits.
2353	*/
2354	nb = nwords << L2DBWORD;
2355
2356	/* now update the appropriate leaves to reflect
2357	* the freed words.
2358	*/
2359	for (; nwords > 0; nwords -= nw) {
2360	/* determine what the leaf value should be
2361	* updated to as the minimum of the l2 number
2362	* of bits being freed and the l2 (max) number
2363	* of bits that can be described by this leaf.
2364	*/
2365	size =
2366	min(LITOL2BSZ
2367	(word, L2LPERDMAP, BUDMIN),
2368	NLSTOL2BSZ(nwords));
2369
2370	/* update the leaf.
2371	*/
2372	rc = dbJoin(tp, leafno: word, newval: size);
2373	if (rc)
2374	return rc;
2375
2376	/* get the number of dmap words handled.
2377	*/
2378	nw = BUDSIZE(size, BUDMIN);
2379	word += nw;
2380	}
2381	}
2382	}
2383
2384	/* update the free count for this dmap.
2385	*/
2386	le32_add_cpu(var: &dp->nfree, val: nblocks);
2387
2388	BMAP_LOCK(bmp);
2389
2390	/* update the free count for the allocation group and
2391	* map.
2392	*/
2393	agno = blkno >> bmp->db_agl2size;
2394	bmp->db_nfree += nblocks;
2395	bmp->db_agfree[agno] += nblocks;
2396
2397	/* check if this allocation group is not completely free and
2398	* if it is currently the maximum (rightmost) allocation group.
2399	* if so, establish the new maximum allocation group number by
2400	* searching left for the first allocation group with allocation.
2401	*/
2402	if ((bmp->db_agfree[agno] == bmp->db_agsize && agno == bmp->db_maxag) ||
2403	(agno == bmp->db_numag - 1 &&
2404	bmp->db_agfree[agno] == (bmp-> db_mapsize & (BPERDMAP - 1)))) {
2405	while (bmp->db_maxag > 0) {
2406	bmp->db_maxag -= 1;
2407	if (bmp->db_agfree[bmp->db_maxag] !=
2408	bmp->db_agsize)
2409	break;
2410	}
2411
2412	/* re-establish the allocation group preference if the
2413	* current preference is right of the maximum allocation
2414	* group.
2415	*/
2416	if (bmp->db_agpref > bmp->db_maxag)
2417	bmp->db_agpref = bmp->db_maxag;
2418	}
2419
2420	BMAP_UNLOCK(bmp);
2421
2422	return 0;
2423	}
2424
2425
2426	/*
2427	* NAME: dbAdjCtl()
2428	*
2429	* FUNCTION: adjust a dmap control page at a specified level to reflect
2430	* the change in a lower level dmap or dmap control page's
2431	* maximum string of free blocks (i.e. a change in the root
2432	* of the lower level object's dmtree) due to the allocation
2433	* or deallocation of a range of blocks with a single dmap.
2434	*
2435	* on entry, this routine is provided with the new value of
2436	* the lower level dmap or dmap control page root and the
2437	* starting block number of the block range whose allocation
2438	* or deallocation resulted in the root change. this range
2439	* is respresented by a single leaf of the current dmapctl
2440	* and the leaf will be updated with this value, possibly
2441	* causing a binary buddy system within the leaves to be
2442	* split or joined. the update may also cause the dmapctl's
2443	* dmtree to be updated.
2444	*
2445	* if the adjustment of the dmap control page, itself, causes its
2446	* root to change, this change will be bubbled up to the next dmap
2447	* control level by a recursive call to this routine, specifying
2448	* the new root value and the next dmap control page level to
2449	* be adjusted.
2450	* PARAMETERS:
2451	* bmp - pointer to bmap descriptor
2452	* blkno - the first block of a block range within a dmap. it is
2453	* the allocation or deallocation of this block range that
2454	* requires the dmap control page to be adjusted.
2455	* newval - the new value of the lower level dmap or dmap control
2456	* page root.
2457	* alloc - 'true' if adjustment is due to an allocation.
2458	* level - current level of dmap control page (i.e. L0, L1, L2) to
2459	* be adjusted.
2460	*
2461	* RETURN VALUES:
2462	* 0 - success
2463	* -EIO - i/o error
2464	*
2465	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2466	*/
2467	static int
2468	dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
2469	{
2470	struct metapage *mp;
2471	s8 oldroot;
2472	int oldval;
2473	s64 lblkno;
2474	struct dmapctl *dcp;
2475	int rc, leafno, ti;
2476
2477	/* get the buffer for the dmap control page for the specified
2478	* block number and control page level.
2479	*/
2480	lblkno = BLKTOCTL(blkno, bmp->db_l2nbperpage, level);
2481	mp = read_metapage(bmp->db_ipbmap, lblkno, PSIZE, 0);
2482	if (mp == NULL)
2483	return -EIO;
2484	dcp = (struct dmapctl *) mp->data;
2485
2486	if (dcp->leafidx != cpu_to_le32(CTLLEAFIND)) {
2487	jfs_error(bmp->db_ipbmap->i_sb, "Corrupt dmapctl page\n");
2488	release_metapage(mp);
2489	return -EIO;
2490	}
2491
2492	/* determine the leaf number corresponding to the block and
2493	* the index within the dmap control tree.
2494	*/
2495	leafno = BLKTOCTLLEAF(blkno, dcp->budmin);
2496	ti = leafno + le32_to_cpu(dcp->leafidx);
2497
2498	/* save the current leaf value and the current root level (i.e.
2499	* maximum l2 free string described by this dmapctl).
2500	*/
2501	oldval = dcp->stree[ti];
2502	oldroot = dcp->stree[ROOT];
2503
2504	/* check if this is a control page update for an allocation.
2505	* if so, update the leaf to reflect the new leaf value using
2506	* dbSplit(); otherwise (deallocation), use dbJoin() to update
2507	* the leaf with the new value. in addition to updating the
2508	* leaf, dbSplit() will also split the binary buddy system of
2509	* the leaves, if required, and bubble new values within the
2510	* dmapctl tree, if required. similarly, dbJoin() will join
2511	* the binary buddy system of leaves and bubble new values up
2512	* the dmapctl tree as required by the new leaf value.
2513	*/
2514	if (alloc) {
2515	/* check if we are in the middle of a binary buddy
2516	* system. this happens when we are performing the
2517	* first allocation out of an allocation group that
2518	* is part (not the first part) of a larger binary
2519	* buddy system. if we are in the middle, back split
2520	* the system prior to calling dbSplit() which assumes
2521	* that it is at the front of a binary buddy system.
2522	*/
2523	if (oldval == NOFREE) {
2524	rc = dbBackSplit(tp: (dmtree_t *) dcp, leafno);
2525	if (rc) {
2526	release_metapage(mp);
2527	return rc;
2528	}
2529	oldval = dcp->stree[ti];
2530	}
2531	dbSplit(tp: (dmtree_t *) dcp, leafno, splitsz: dcp->budmin, newval);
2532	} else {
2533	rc = dbJoin(tp: (dmtree_t *) dcp, leafno, newval);
2534	if (rc) {
2535	release_metapage(mp);
2536	return rc;
2537	}
2538	}
2539
2540	/* check if the root of the current dmap control page changed due
2541	* to the update and if the current dmap control page is not at
2542	* the current top level (i.e. L0, L1, L2) of the map. if so (i.e.
2543	* root changed and this is not the top level), call this routine
2544	* again (recursion) for the next higher level of the mapping to
2545	* reflect the change in root for the current dmap control page.
2546	*/
2547	if (dcp->stree[ROOT] != oldroot) {
2548	/* are we below the top level of the map. if so,
2549	* bubble the root up to the next higher level.
2550	*/
2551	if (level < bmp->db_maxlevel) {
2552	/* bubble up the new root of this dmap control page to
2553	* the next level.
2554	*/
2555	if ((rc =
2556	dbAdjCtl(bmp, blkno, newval: dcp->stree[ROOT], alloc,
2557	level: level + 1))) {
2558	/* something went wrong in bubbling up the new
2559	* root value, so backout the changes to the
2560	* current dmap control page.
2561	*/
2562	if (alloc) {
2563	dbJoin(tp: (dmtree_t *) dcp, leafno,
2564	newval: oldval);
2565	} else {
2566	/* the dbJoin() above might have
2567	* caused a larger binary buddy system
2568	* to form and we may now be in the
2569	* middle of it. if this is the case,
2570	* back split the buddies.
2571	*/
2572	if (dcp->stree[ti] == NOFREE)
2573	dbBackSplit(tp: (dmtree_t *)
2574	dcp, leafno);
2575	dbSplit(tp: (dmtree_t *) dcp, leafno,
2576	splitsz: dcp->budmin, newval: oldval);
2577	}
2578
2579	/* release the buffer and return the error.
2580	*/
2581	release_metapage(mp);
2582	return (rc);
2583	}
2584	} else {
2585	/* we're at the top level of the map. update
2586	* the bmap control page to reflect the size
2587	* of the maximum free buddy system.
2588	*/
2589	assert(level == bmp->db_maxlevel);
2590	if (bmp->db_maxfreebud != oldroot) {
2591	jfs_error(bmp->db_ipbmap->i_sb,
2592	"the maximum free buddy is not the old root\n");
2593	}
2594	bmp->db_maxfreebud = dcp->stree[ROOT];
2595	}
2596	}
2597
2598	/* write the buffer.
2599	*/
2600	write_metapage(mp);
2601
2602	return (0);
2603	}
2604
2605
2606	/*
2607	* NAME: dbSplit()
2608	*
2609	* FUNCTION: update the leaf of a dmtree with a new value, splitting
2610	* the leaf from the binary buddy system of the dmtree's
2611	* leaves, as required.
2612	*
2613	* PARAMETERS:
2614	* tp - pointer to the tree containing the leaf.
2615	* leafno - the number of the leaf to be updated.
2616	* splitsz - the size the binary buddy system starting at the leaf
2617	* must be split to, specified as the log2 number of blocks.
2618	* newval - the new value for the leaf.
2619	*
2620	* RETURN VALUES: none
2621	*
2622	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2623	*/
2624	static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
2625	{
2626	int budsz;
2627	int cursz;
2628	s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2629
2630	/* check if the leaf needs to be split.
2631	*/
2632	if (leaf[leafno] > tp->dmt_budmin) {
2633	/* the split occurs by cutting the buddy system in half
2634	* at the specified leaf until we reach the specified
2635	* size. pick up the starting split size (current size
2636	* - 1 in l2) and the corresponding buddy size.
2637	*/
2638	cursz = leaf[leafno] - 1;
2639	budsz = BUDSIZE(cursz, tp->dmt_budmin);
2640
2641	/* split until we reach the specified size.
2642	*/
2643	while (cursz >= splitsz) {
2644	/* update the buddy's leaf with its new value.
2645	*/
2646	dbAdjTree(tp, leafno: leafno ^ budsz, newval: cursz);
2647
2648	/* on to the next size and buddy.
2649	*/
2650	cursz -= 1;
2651	budsz >>= 1;
2652	}
2653	}
2654
2655	/* adjust the dmap tree to reflect the specified leaf's new
2656	* value.
2657	*/
2658	dbAdjTree(tp, leafno, newval);
2659	}
2660
2661
2662	/*
2663	* NAME: dbBackSplit()
2664	*
2665	* FUNCTION: back split the binary buddy system of dmtree leaves
2666	* that hold a specified leaf until the specified leaf
2667	* starts its own binary buddy system.
2668	*
2669	* the allocators typically perform allocations at the start
2670	* of binary buddy systems and dbSplit() is used to accomplish
2671	* any required splits. in some cases, however, allocation
2672	* may occur in the middle of a binary system and requires a
2673	* back split, with the split proceeding out from the middle of
2674	* the system (less efficient) rather than the start of the
2675	* system (more efficient). the cases in which a back split
2676	* is required are rare and are limited to the first allocation
2677	* within an allocation group which is a part (not first part)
2678	* of a larger binary buddy system and a few exception cases
2679	* in which a previous join operation must be backed out.
2680	*
2681	* PARAMETERS:
2682	* tp - pointer to the tree containing the leaf.
2683	* leafno - the number of the leaf to be updated.
2684	*
2685	* RETURN VALUES: none
2686	*
2687	* serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
2688	*/
2689	static int dbBackSplit(dmtree_t * tp, int leafno)
2690	{
2691	int budsz, bud, w, bsz, size;
2692	int cursz;
2693	s8 *leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2694
2695	/* leaf should be part (not first part) of a binary
2696	* buddy system.
2697	*/
2698	assert(leaf[leafno] == NOFREE);
2699
2700	/* the back split is accomplished by iteratively finding the leaf
2701	* that starts the buddy system that contains the specified leaf and
2702	* splitting that system in two. this iteration continues until
2703	* the specified leaf becomes the start of a buddy system.
2704	*
2705	* determine maximum possible l2 size for the specified leaf.
2706	*/
2707	size =
2708	LITOL2BSZ(leafno, le32_to_cpu(tp->dmt_l2nleafs),
2709	tp->dmt_budmin);
2710
2711	/* determine the number of leaves covered by this size. this
2712	* is the buddy size that we will start with as we search for
2713	* the buddy system that contains the specified leaf.
2714	*/
2715	budsz = BUDSIZE(size, tp->dmt_budmin);
2716
2717	/* back split.
2718	*/
2719	while (leaf[leafno] == NOFREE) {
2720	/* find the leftmost buddy leaf.
2721	*/
2722	for (w = leafno, bsz = budsz;; bsz <<= 1,
2723	w = (w < bud) ? w : bud) {
2724	if (bsz >= le32_to_cpu(tp->dmt_nleafs)) {
2725	jfs_err("JFS: block map error in dbBackSplit");
2726	return -EIO;
2727	}
2728
2729	/* determine the buddy.
2730	*/
2731	bud = w ^ bsz;
2732
2733	/* check if this buddy is the start of the system.
2734	*/
2735	if (leaf[bud] != NOFREE) {
2736	/* split the leaf at the start of the
2737	* system in two.
2738	*/
2739	cursz = leaf[bud] - 1;
2740	dbSplit(tp, leafno: bud, splitsz: cursz, newval: cursz);
2741	break;
2742	}
2743	}
2744	}
2745
2746	if (leaf[leafno] != size) {
2747	jfs_err("JFS: wrong leaf value in dbBackSplit");
2748	return -EIO;
2749	}
2750	return 0;
2751	}
2752
2753
2754	/*
2755	* NAME: dbJoin()
2756	*
2757	* FUNCTION: update the leaf of a dmtree with a new value, joining
2758	* the leaf with other leaves of the dmtree into a multi-leaf
2759	* binary buddy system, as required.
2760	*
2761	* PARAMETERS:
2762	* tp - pointer to the tree containing the leaf.
2763	* leafno - the number of the leaf to be updated.
2764	* newval - the new value for the leaf.
2765	*
2766	* RETURN VALUES: none
2767	*/
2768	static int dbJoin(dmtree_t * tp, int leafno, int newval)
2769	{
2770	int budsz, buddy;
2771	s8 *leaf;
2772
2773	/* can the new leaf value require a join with other leaves ?
2774	*/
2775	if (newval >= tp->dmt_budmin) {
2776	/* pickup a pointer to the leaves of the tree.
2777	*/
2778	leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
2779
2780	/* try to join the specified leaf into a large binary
2781	* buddy system. the join proceeds by attempting to join
2782	* the specified leafno with its buddy (leaf) at new value.
2783	* if the join occurs, we attempt to join the left leaf
2784	* of the joined buddies with its buddy at new value + 1.
2785	* we continue to join until we find a buddy that cannot be
2786	* joined (does not have a value equal to the size of the
2787	* last join) or until all leaves have been joined into a
2788	* single system.
2789	*
2790	* get the buddy size (number of words covered) of
2791	* the new value.
2792	*/
2793	budsz = BUDSIZE(newval, tp->dmt_budmin);
2794
2795	/* try to join.
2796	*/
2797	while (budsz < le32_to_cpu(tp->dmt_nleafs)) {
2798	/* get the buddy leaf.
2799	*/
2800	buddy = leafno ^ budsz;
2801
2802	/* if the leaf's new value is greater than its
2803	* buddy's value, we join no more.
2804	*/
2805	if (newval > leaf[buddy])
2806	break;
2807
2808	/* It shouldn't be less */
2809	if (newval < leaf[buddy])
2810	return -EIO;
2811
2812	/* check which (leafno or buddy) is the left buddy.
2813	* the left buddy gets to claim the blocks resulting
2814	* from the join while the right gets to claim none.
2815	* the left buddy is also eligible to participate in
2816	* a join at the next higher level while the right
2817	* is not.
2818	*
2819	*/
2820	if (leafno < buddy) {
2821	/* leafno is the left buddy.
2822	*/
2823	dbAdjTree(tp, leafno: buddy, NOFREE);
2824	} else {
2825	/* buddy is the left buddy and becomes
2826	* leafno.
2827	*/
2828	dbAdjTree(tp, leafno, NOFREE);
2829	leafno = buddy;
2830	}
2831
2832	/* on to try the next join.
2833	*/
2834	newval += 1;
2835	budsz <<= 1;
2836	}
2837	}
2838
2839	/* update the leaf value.
2840	*/
2841	dbAdjTree(tp, leafno, newval);
2842
2843	return 0;
2844	}
2845
2846
2847	/*
2848	* NAME: dbAdjTree()
2849	*
2850	* FUNCTION: update a leaf of a dmtree with a new value, adjusting
2851	* the dmtree, as required, to reflect the new leaf value.
2852	* the combination of any buddies must already be done before
2853	* this is called.
2854	*
2855	* PARAMETERS:
2856	* tp - pointer to the tree to be adjusted.
2857	* leafno - the number of the leaf to be updated.
2858	* newval - the new value for the leaf.
2859	*
2860	* RETURN VALUES: none
2861	*/
2862	static void dbAdjTree(dmtree_t * tp, int leafno, int newval)
2863	{
2864	int lp, pp, k;
2865	int max;
2866
2867	/* pick up the index of the leaf for this leafno.
2868	*/
2869	lp = leafno + le32_to_cpu(tp->dmt_leafidx);
2870
2871	/* is the current value the same as the old value ? if so,
2872	* there is nothing to do.
2873	*/
2874	if (tp->dmt_stree[lp] == newval)
2875	return;
2876
2877	/* set the new value.
2878	*/
2879	tp->dmt_stree[lp] = newval;
2880
2881	/* bubble the new value up the tree as required.
2882	*/
2883	for (k = 0; k < le32_to_cpu(tp->dmt_height); k++) {
2884	/* get the index of the first leaf of the 4 leaf
2885	* group containing the specified leaf (leafno).
2886	*/
2887	lp = ((lp - 1) & ~0x03) + 1;
2888
2889	/* get the index of the parent of this 4 leaf group.
2890	*/
2891	pp = (lp - 1) >> 2;
2892
2893	/* determine the maximum of the 4 leaves.
2894	*/
2895	max = TREEMAX(cp: &tp->dmt_stree[lp]);
2896
2897	/* if the maximum of the 4 is the same as the
2898	* parent's value, we're done.
2899	*/
2900	if (tp->dmt_stree[pp] == max)
2901	break;
2902
2903	/* parent gets new value.
2904	*/
2905	tp->dmt_stree[pp] = max;
2906
2907	/* parent becomes leaf for next go-round.
2908	*/
2909	lp = pp;
2910	}
2911	}
2912
2913
2914	/*
2915	* NAME: dbFindLeaf()
2916	*
2917	* FUNCTION: search a dmtree_t for sufficient free blocks, returning
2918	* the index of a leaf describing the free blocks if
2919	* sufficient free blocks are found.
2920	*
2921	* the search starts at the top of the dmtree_t tree and
2922	* proceeds down the tree to the leftmost leaf with sufficient
2923	* free space.
2924	*
2925	* PARAMETERS:
2926	* tp - pointer to the tree to be searched.
2927	* l2nb - log2 number of free blocks to search for.
2928	* leafidx - return pointer to be set to the index of the leaf
2929	* describing at least l2nb free blocks if sufficient
2930	* free blocks are found.
2931	* is_ctl - determines if the tree is of type ctl
2932	*
2933	* RETURN VALUES:
2934	* 0 - success
2935	* -ENOSPC - insufficient free blocks.
2936	*/
2937	static int dbFindLeaf(dmtree_t *tp, int l2nb, int *leafidx, bool is_ctl)
2938	{
2939	int ti, n = 0, k, x = 0;
2940	int max_size;
2941
2942	max_size = is_ctl ? CTLTREESIZE : TREESIZE;
2943
2944	/* first check the root of the tree to see if there is
2945	* sufficient free space.
2946	*/
2947	if (l2nb > tp->dmt_stree[ROOT])
2948	return -ENOSPC;
2949
2950	/* sufficient free space available. now search down the tree
2951	* starting at the next level for the leftmost leaf that
2952	* describes sufficient free space.
2953	*/
2954	for (k = le32_to_cpu(tp->dmt_height), ti = 1;
2955	k > 0; k--, ti = ((ti + n) << 2) + 1) {
2956	/* search the four nodes at this level, starting from
2957	* the left.
2958	*/
2959	for (x = ti, n = 0; n < 4; n++) {
2960	/* sufficient free space found. move to the next
2961	* level (or quit if this is the last level).
2962	*/
2963	if (x + n > max_size)
2964	return -ENOSPC;
2965	if (l2nb <= tp->dmt_stree[x + n])
2966	break;
2967	}
2968
2969	/* better have found something since the higher
2970	* levels of the tree said it was here.
2971	*/
2972	assert(n < 4);
2973	}
2974
2975	/* set the return to the leftmost leaf describing sufficient
2976	* free space.
2977	*/
2978	*leafidx = x + n - le32_to_cpu(tp->dmt_leafidx);
2979
2980	return (0);
2981	}
2982
2983
2984	/*
2985	* NAME: dbFindBits()
2986	*
2987	* FUNCTION: find a specified number of binary buddy free bits within a
2988	* dmap bitmap word value.
2989	*
2990	* this routine searches the bitmap value for (1 << l2nb) free
2991	* bits at (1 << l2nb) alignments within the value.
2992	*
2993	* PARAMETERS:
2994	* word - dmap bitmap word value.
2995	* l2nb - number of free bits specified as a log2 number.
2996	*
2997	* RETURN VALUES:
2998	* starting bit number of free bits.
2999	*/
3000	static int dbFindBits(u32 word, int l2nb)
3001	{
3002	int bitno, nb;
3003	u32 mask;
3004
3005	/* get the number of bits.
3006	*/
3007	nb = 1 << l2nb;
3008	assert(nb <= DBWORD);
3009
3010	/* complement the word so we can use a mask (i.e. 0s represent
3011	* free bits) and compute the mask.
3012	*/
3013	word = ~word;
3014	mask = ONES << (DBWORD - nb);
3015
3016	/* scan the word for nb free bits at nb alignments.
3017	*/
3018	for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
3019	if ((mask & word) == mask)
3020	break;
3021	}
3022
3023	ASSERT(bitno < 32);
3024
3025	/* return the bit number.
3026	*/
3027	return (bitno);
3028	}
3029
3030
3031	/*
3032	* NAME: dbMaxBud(u8 *cp)
3033	*
3034	* FUNCTION: determine the largest binary buddy string of free
3035	* bits within 32-bits of the map.
3036	*
3037	* PARAMETERS:
3038	* cp - pointer to the 32-bit value.
3039	*
3040	* RETURN VALUES:
3041	* largest binary buddy of free bits within a dmap word.
3042	*/
3043	static int dbMaxBud(u8 * cp)
3044	{
3045	signed char tmp1, tmp2;
3046
3047	/* check if the wmap word is all free. if so, the
3048	* free buddy size is BUDMIN.
3049	*/
3050	if (*((uint *) cp) == 0)
3051	return (BUDMIN);
3052
3053	/* check if the wmap word is half free. if so, the
3054	* free buddy size is BUDMIN-1.
3055	*/
3056	if (*((u16 *) cp) == 0 || *((u16 *) cp + 1) == 0)
3057	return (BUDMIN - 1);
3058
3059	/* not all free or half free. determine the free buddy
3060	* size thru table lookup using quarters of the wmap word.
3061	*/
3062	tmp1 = max(budtab[cp[2]], budtab[cp[3]]);
3063	tmp2 = max(budtab[cp[0]], budtab[cp[1]]);
3064	return (max(tmp1, tmp2));
3065	}
3066
3067
3068	/*
3069	* NAME: cnttz(uint word)
3070	*
3071	* FUNCTION: determine the number of trailing zeros within a 32-bit
3072	* value.
3073	*
3074	* PARAMETERS:
3075	* value - 32-bit value to be examined.
3076	*
3077	* RETURN VALUES:
3078	* count of trailing zeros
3079	*/
3080	static int cnttz(u32 word)
3081	{
3082	int n;
3083
3084	for (n = 0; n < 32; n++, word >>= 1) {
3085	if (word & 0x01)
3086	break;
3087	}
3088
3089	return (n);
3090	}
3091
3092
3093	/*
3094	* NAME: cntlz(u32 value)
3095	*
3096	* FUNCTION: determine the number of leading zeros within a 32-bit
3097	* value.
3098	*
3099	* PARAMETERS:
3100	* value - 32-bit value to be examined.
3101	*
3102	* RETURN VALUES:
3103	* count of leading zeros
3104	*/
3105	static int cntlz(u32 value)
3106	{
3107	int n;
3108
3109	for (n = 0; n < 32; n++, value <<= 1) {
3110	if (value & HIGHORDER)
3111	break;
3112	}
3113	return (n);
3114	}
3115
3116
3117	/*
3118	* NAME: blkstol2(s64 nb)
3119	*
3120	* FUNCTION: convert a block count to its log2 value. if the block
3121	* count is not a l2 multiple, it is rounded up to the next
3122	* larger l2 multiple.
3123	*
3124	* PARAMETERS:
3125	* nb - number of blocks
3126	*
3127	* RETURN VALUES:
3128	* log2 number of blocks
3129	*/
3130	static int blkstol2(s64 nb)
3131	{
3132	int l2nb;
3133	s64 mask; /* meant to be signed */
3134
3135	mask = (s64) 1 << (64 - 1);
3136
3137	/* count the leading bits.
3138	*/
3139	for (l2nb = 0; l2nb < 64; l2nb++, mask >>= 1) {
3140	/* leading bit found.
3141	*/
3142	if (nb & mask) {
3143	/* determine the l2 value.
3144	*/
3145	l2nb = (64 - 1) - l2nb;
3146
3147	/* check if we need to round up.
3148	*/
3149	if (~mask & nb)
3150	l2nb++;
3151
3152	return (l2nb);
3153	}
3154	}
3155	assert(0);
3156	return 0; /* fix compiler warning */
3157	}
3158
3159
3160	/*
3161	* NAME: dbAllocBottomUp()
3162	*
3163	* FUNCTION: alloc the specified block range from the working block
3164	* allocation map.
3165	*
3166	* the blocks will be alloc from the working map one dmap
3167	* at a time.
3168	*
3169	* PARAMETERS:
3170	* ip - pointer to in-core inode;
3171	* blkno - starting block number to be freed.
3172	* nblocks - number of blocks to be freed.
3173	*
3174	* RETURN VALUES:
3175	* 0 - success
3176	* -EIO - i/o error
3177	*/
3178	int dbAllocBottomUp(struct inode *ip, s64 blkno, s64 nblocks)
3179	{
3180	struct metapage *mp;
3181	struct dmap *dp;
3182	int nb, rc;
3183	s64 lblkno, rem;
3184	struct inode *ipbmap = JFS_SBI(sb: ip->i_sb)->ipbmap;
3185	struct bmap *bmp = JFS_SBI(sb: ip->i_sb)->bmap;
3186
3187	IREAD_LOCK(ipbmap, RDWRLOCK_DMAP);
3188
3189	/* block to be allocated better be within the mapsize. */
3190	ASSERT(nblocks <= bmp->db_mapsize - blkno);
3191
3192	/*
3193	* allocate the blocks a dmap at a time.
3194	*/
3195	mp = NULL;
3196	for (rem = nblocks; rem > 0; rem -= nb, blkno += nb) {
3197	/* release previous dmap if any */
3198	if (mp) {
3199	write_metapage(mp);
3200	}
3201
3202	/* get the buffer for the current dmap. */
3203	lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
3204	mp = read_metapage(ipbmap, lblkno, PSIZE, 0);
3205	if (mp == NULL) {
3206	IREAD_UNLOCK(ipbmap);
3207	return -EIO;
3208	}
3209	dp = (struct dmap *) mp->data;
3210
3211	/* determine the number of blocks to be allocated from
3212	* this dmap.
3213	*/
3214	nb = min(rem, BPERDMAP - (blkno & (BPERDMAP - 1)));
3215
3216	/* allocate the blocks. */
3217	if ((rc = dbAllocDmapBU(bmp, dp, blkno, nblocks: nb))) {
3218	release_metapage(mp);
3219	IREAD_UNLOCK(ipbmap);
3220	return (rc);
3221	}
3222	}
3223
3224	/* write the last buffer. */
3225	write_metapage(mp);
3226
3227	IREAD_UNLOCK(ipbmap);
3228
3229	return (0);
3230	}
3231
3232
3233	static int dbAllocDmapBU(struct bmap * bmp, struct dmap * dp, s64 blkno,
3234	int nblocks)
3235	{
3236	int rc;
3237	int dbitno, word, rembits, nb, nwords, wbitno, agno;
3238	s8 oldroot;
3239	struct dmaptree *tp = (struct dmaptree *) & dp->tree;
3240
3241	/* save the current value of the root (i.e. maximum free string)
3242	* of the dmap tree.
3243	*/
3244	oldroot = tp->stree[ROOT];
3245
3246	/* determine the bit number and word within the dmap of the
3247	* starting block.
3248	*/
3249	dbitno = blkno & (BPERDMAP - 1);
3250	word = dbitno >> L2DBWORD;
3251
3252	/* block range better be within the dmap */
3253	assert(dbitno + nblocks <= BPERDMAP);
3254
3255	/* allocate the bits of the dmap's words corresponding to the block
3256	* range. not all bits of the first and last words may be contained
3257	* within the block range. if this is the case, we'll work against
3258	* those words (i.e. partial first and/or last) on an individual basis
3259	* (a single pass), allocating the bits of interest by hand and
3260	* updating the leaf corresponding to the dmap word. a single pass
3261	* will be used for all dmap words fully contained within the
3262	* specified range. within this pass, the bits of all fully contained
3263	* dmap words will be marked as free in a single shot and the leaves
3264	* will be updated. a single leaf may describe the free space of
3265	* multiple dmap words, so we may update only a subset of the actual
3266	* leaves corresponding to the dmap words of the block range.
3267	*/
3268	for (rembits = nblocks; rembits > 0; rembits -= nb, dbitno += nb) {
3269	/* determine the bit number within the word and
3270	* the number of bits within the word.
3271	*/
3272	wbitno = dbitno & (DBWORD - 1);
3273	nb = min(rembits, DBWORD - wbitno);
3274
3275	/* check if only part of a word is to be allocated.
3276	*/
3277	if (nb < DBWORD) {
3278	/* allocate (set to 1) the appropriate bits within
3279	* this dmap word.
3280	*/
3281	dp->wmap[word] |= cpu_to_le32(ONES << (DBWORD - nb)
3282	>> wbitno);
3283
3284	word++;
3285	} else {
3286	/* one or more dmap words are fully contained
3287	* within the block range. determine how many
3288	* words and allocate (set to 1) the bits of these
3289	* words.
3290	*/
3291	nwords = rembits >> L2DBWORD;
3292	memset(&dp->wmap[word], (int) ONES, nwords * 4);
3293
3294	/* determine how many bits */
3295	nb = nwords << L2DBWORD;
3296	word += nwords;
3297	}
3298	}
3299
3300	/* update the free count for this dmap */
3301	le32_add_cpu(var: &dp->nfree, val: -nblocks);
3302
3303	/* reconstruct summary tree */
3304	dbInitDmapTree(dp);
3305
3306	BMAP_LOCK(bmp);
3307
3308	/* if this allocation group is completely free,
3309	* update the highest active allocation group number
3310	* if this allocation group is the new max.
3311	*/
3312	agno = blkno >> bmp->db_agl2size;
3313	if (agno > bmp->db_maxag)
3314	bmp->db_maxag = agno;
3315
3316	/* update the free count for the allocation group and map */
3317	bmp->db_agfree[agno] -= nblocks;
3318	bmp->db_nfree -= nblocks;
3319
3320	BMAP_UNLOCK(bmp);
3321
3322	/* if the root has not changed, done. */
3323	if (tp->stree[ROOT] == oldroot)
3324	return (0);
3325
3326	/* root changed. bubble the change up to the dmap control pages.
3327	* if the adjustment of the upper level control pages fails,
3328	* backout the bit allocation (thus making everything consistent).
3329	*/
3330	if ((rc = dbAdjCtl(bmp, blkno, newval: tp->stree[ROOT], alloc: 1, level: 0)))
3331	dbFreeBits(bmp, dp, blkno, nblocks);
3332
3333	return (rc);
3334	}
3335
3336
3337	/*
3338	* NAME: dbExtendFS()
3339	*
3340	* FUNCTION: extend bmap from blkno for nblocks;
3341	* dbExtendFS() updates bmap ready for dbAllocBottomUp();
3342	*
3343	* L2
3344	* |
3345	* L1---------------------------------L1
3346	* | |
3347	* L0---------L0---------L0 L0---------L0---------L0
3348	* | | | | | |
3349	* d0,...,dn d0,...,dn d0,...,dn d0,...,dn d0,...,dn d0,.,dm;
3350	* L2L1L0d0,...,dnL0d0,...,dnL0d0,...,dnL1L0d0,...,dnL0d0,...,dnL0d0,..dm
3351	*
3352	* <---old---><----------------------------extend----------------------->
3353	*/
3354	int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks)
3355	{
3356	struct jfs_sb_info *sbi = JFS_SBI(sb: ipbmap->i_sb);
3357	int nbperpage = sbi->nbperpage;
3358	int i, i0 = true, j, j0 = true, k, n;
3359	s64 newsize;
3360	s64 p;
3361	struct metapage *mp, *l2mp, *l1mp = NULL, *l0mp = NULL;
3362	struct dmapctl *l2dcp, *l1dcp, *l0dcp;
3363	struct dmap *dp;
3364	s8 *l0leaf, *l1leaf, *l2leaf;
3365	struct bmap *bmp = sbi->bmap;
3366	int agno, l2agsize, oldl2agsize;
3367	s64 ag_rem;
3368
3369	newsize = blkno + nblocks;
3370
3371	jfs_info("dbExtendFS: blkno:%Ld nblocks:%Ld newsize:%Ld",
3372	(long long) blkno, (long long) nblocks, (long long) newsize);
3373
3374	/*
3375	* initialize bmap control page.
3376	*
3377	* all the data in bmap control page should exclude
3378	* the mkfs hidden dmap page.
3379	*/
3380
3381	/* update mapsize */
3382	bmp->db_mapsize = newsize;
3383	bmp->db_maxlevel = BMAPSZTOLEV(bmp->db_mapsize);
3384
3385	/* compute new AG size */
3386	l2agsize = dbGetL2AGSize(nblocks: newsize);
3387	oldl2agsize = bmp->db_agl2size;
3388
3389	bmp->db_agl2size = l2agsize;
3390	bmp->db_agsize = 1 << l2agsize;
3391
3392	/* compute new number of AG */
3393	agno = bmp->db_numag;
3394	bmp->db_numag = newsize >> l2agsize;
3395	bmp->db_numag += ((u32) newsize % (u32) bmp->db_agsize) ? 1 : 0;
3396
3397	/*
3398	* reconfigure db_agfree[]
3399	* from old AG configuration to new AG configuration;
3400	*
3401	* coalesce contiguous k (newAGSize/oldAGSize) AGs;
3402	* i.e., (AGi, ..., AGj) where i = k*n and j = k*(n+1) - 1 to AGn;
3403	* note: new AG size = old AG size * (2**x).
3404	*/
3405	if (l2agsize == oldl2agsize)
3406	goto extend;
3407	k = 1 << (l2agsize - oldl2agsize);
3408	ag_rem = bmp->db_agfree[0]; /* save agfree[0] */
3409	for (i = 0, n = 0; i < agno; n++) {
3410	bmp->db_agfree[n] = 0; /* init collection point */
3411
3412	/* coalesce contiguous k AGs; */
3413	for (j = 0; j < k && i < agno; j++, i++) {
3414	/* merge AGi to AGn */
3415	bmp->db_agfree[n] += bmp->db_agfree[i];
3416	}
3417	}
3418	bmp->db_agfree[0] += ag_rem; /* restore agfree[0] */
3419
3420	for (; n < MAXAG; n++)
3421	bmp->db_agfree[n] = 0;
3422
3423	/*
3424	* update highest active ag number
3425	*/
3426
3427	bmp->db_maxag = bmp->db_maxag / k;
3428
3429	/*
3430	* extend bmap
3431	*
3432	* update bit maps and corresponding level control pages;
3433	* global control page db_nfree, db_agfree[agno], db_maxfreebud;
3434	*/
3435	extend:
3436	/* get L2 page */
3437	p = BMAPBLKNO + nbperpage; /* L2 page */
3438	l2mp = read_metapage(ipbmap, p, PSIZE, 0);
3439	if (!l2mp) {
3440	jfs_error(ipbmap->i_sb, "L2 page could not be read\n");
3441	return -EIO;
3442	}
3443	l2dcp = (struct dmapctl *) l2mp->data;
3444
3445	/* compute start L1 */
3446	k = blkno >> L2MAXL1SIZE;
3447	l2leaf = l2dcp->stree + CTLLEAFIND + k;
3448	p = BLKTOL1(blkno, sbi->l2nbperpage); /* L1 page */
3449
3450	/*
3451	* extend each L1 in L2
3452	*/
3453	for (; k < LPERCTL; k++, p += nbperpage) {
3454	/* get L1 page */
3455	if (j0) {
3456	/* read in L1 page: (blkno & (MAXL1SIZE - 1)) */
3457	l1mp = read_metapage(ipbmap, p, PSIZE, 0);
3458	if (l1mp == NULL)
3459	goto errout;
3460	l1dcp = (struct dmapctl *) l1mp->data;
3461
3462	/* compute start L0 */
3463	j = (blkno & (MAXL1SIZE - 1)) >> L2MAXL0SIZE;
3464	l1leaf = l1dcp->stree + CTLLEAFIND + j;
3465	p = BLKTOL0(blkno, sbi->l2nbperpage);
3466	j0 = false;
3467	} else {
3468	/* assign/init L1 page */
3469	l1mp = get_metapage(ipbmap, p, PSIZE, 0);
3470	if (l1mp == NULL)
3471	goto errout;
3472
3473	l1dcp = (struct dmapctl *) l1mp->data;
3474
3475	/* compute start L0 */
3476	j = 0;
3477	l1leaf = l1dcp->stree + CTLLEAFIND;
3478	p += nbperpage; /* 1st L0 of L1.k */
3479	}
3480
3481	/*
3482	* extend each L0 in L1
3483	*/
3484	for (; j < LPERCTL; j++) {
3485	/* get L0 page */
3486	if (i0) {
3487	/* read in L0 page: (blkno & (MAXL0SIZE - 1)) */
3488
3489	l0mp = read_metapage(ipbmap, p, PSIZE, 0);
3490	if (l0mp == NULL)
3491	goto errout;
3492	l0dcp = (struct dmapctl *) l0mp->data;
3493
3494	/* compute start dmap */
3495	i = (blkno & (MAXL0SIZE - 1)) >>
3496	L2BPERDMAP;
3497	l0leaf = l0dcp->stree + CTLLEAFIND + i;
3498	p = BLKTODMAP(blkno,
3499	sbi->l2nbperpage);
3500	i0 = false;
3501	} else {
3502	/* assign/init L0 page */
3503	l0mp = get_metapage(ipbmap, p, PSIZE, 0);
3504	if (l0mp == NULL)
3505	goto errout;
3506
3507	l0dcp = (struct dmapctl *) l0mp->data;
3508
3509	/* compute start dmap */
3510	i = 0;
3511	l0leaf = l0dcp->stree + CTLLEAFIND;
3512	p += nbperpage; /* 1st dmap of L0.j */
3513	}
3514
3515	/*
3516	* extend each dmap in L0
3517	*/
3518	for (; i < LPERCTL; i++) {
3519	/*
3520	* reconstruct the dmap page, and
3521	* initialize corresponding parent L0 leaf
3522	*/
3523	if ((n = blkno & (BPERDMAP - 1))) {
3524	/* read in dmap page: */
3525	mp = read_metapage(ipbmap, p,
3526	PSIZE, 0);
3527	if (mp == NULL)
3528	goto errout;
3529	n = min(nblocks, (s64)BPERDMAP - n);
3530	} else {
3531	/* assign/init dmap page */
3532	mp = read_metapage(ipbmap, p,
3533	PSIZE, 0);
3534	if (mp == NULL)
3535	goto errout;
3536
3537	n = min_t(s64, nblocks, BPERDMAP);
3538	}
3539
3540	dp = (struct dmap *) mp->data;
3541	*l0leaf = dbInitDmap(dp, blkno, nblocks: n);
3542
3543	bmp->db_nfree += n;
3544	agno = le64_to_cpu(dp->start) >> l2agsize;
3545	bmp->db_agfree[agno] += n;
3546
3547	write_metapage(mp);
3548
3549	l0leaf++;
3550	p += nbperpage;
3551
3552	blkno += n;
3553	nblocks -= n;
3554	if (nblocks == 0)
3555	break;
3556	} /* for each dmap in a L0 */
3557
3558	/*
3559	* build current L0 page from its leaves, and
3560	* initialize corresponding parent L1 leaf
3561	*/
3562	*l1leaf = dbInitDmapCtl(dcp: l0dcp, level: 0, i: ++i);
3563	write_metapage(mp: l0mp);
3564	l0mp = NULL;
3565
3566	if (nblocks)
3567	l1leaf++; /* continue for next L0 */
3568	else {
3569	/* more than 1 L0 ? */
3570	if (j > 0)
3571	break; /* build L1 page */
3572	else {
3573	/* summarize in global bmap page */
3574	bmp->db_maxfreebud = *l1leaf;
3575	release_metapage(l1mp);
3576	release_metapage(l2mp);
3577	goto finalize;
3578	}
3579	}
3580	} /* for each L0 in a L1 */
3581
3582	/*
3583	* build current L1 page from its leaves, and
3584	* initialize corresponding parent L2 leaf
3585	*/
3586	*l2leaf = dbInitDmapCtl(dcp: l1dcp, level: 1, i: ++j);
3587	write_metapage(mp: l1mp);
3588	l1mp = NULL;
3589
3590	if (nblocks)
3591	l2leaf++; /* continue for next L1 */
3592	else {
3593	/* more than 1 L1 ? */
3594	if (k > 0)
3595	break; /* build L2 page */
3596	else {
3597	/* summarize in global bmap page */
3598	bmp->db_maxfreebud = *l2leaf;
3599	release_metapage(l2mp);
3600	goto finalize;
3601	}
3602	}
3603	} /* for each L1 in a L2 */
3604
3605	jfs_error(ipbmap->i_sb, "function has not returned as expected\n");
3606	errout:
3607	if (l0mp)
3608	release_metapage(l0mp);
3609	if (l1mp)
3610	release_metapage(l1mp);
3611	release_metapage(l2mp);
3612	return -EIO;
3613
3614	/*
3615	* finalize bmap control page
3616	*/
3617	finalize:
3618
3619	return 0;
3620	}
3621
3622
3623	/*
3624	* dbFinalizeBmap()
3625	*/
3626	void dbFinalizeBmap(struct inode *ipbmap)
3627	{
3628	struct bmap *bmp = JFS_SBI(sb: ipbmap->i_sb)->bmap;
3629	int actags, inactags, l2nl;
3630	s64 ag_rem, actfree, inactfree, avgfree;
3631	int i, n;
3632
3633	/*
3634	* finalize bmap control page
3635	*/
3636	//finalize:
3637	/*
3638	* compute db_agpref: preferred ag to allocate from
3639	* (the leftmost ag with average free space in it);
3640	*/
3641	//agpref:
3642	/* get the number of active ags and inactive ags */
3643	actags = bmp->db_maxag + 1;
3644	inactags = bmp->db_numag - actags;
3645	ag_rem = bmp->db_mapsize & (bmp->db_agsize - 1); /* ??? */
3646
3647	/* determine how many blocks are in the inactive allocation
3648	* groups. in doing this, we must account for the fact that
3649	* the rightmost group might be a partial group (i.e. file
3650	* system size is not a multiple of the group size).
3651	*/
3652	inactfree = (inactags && ag_rem) ?
3653	((inactags - 1) << bmp->db_agl2size) + ag_rem
3654	: inactags << bmp->db_agl2size;
3655
3656	/* determine how many free blocks are in the active
3657	* allocation groups plus the average number of free blocks
3658	* within the active ags.
3659	*/
3660	actfree = bmp->db_nfree - inactfree;
3661	avgfree = (u32) actfree / (u32) actags;
3662
3663	/* if the preferred allocation group has not average free space.
3664	* re-establish the preferred group as the leftmost
3665	* group with average free space.
3666	*/
3667	if (bmp->db_agfree[bmp->db_agpref] < avgfree) {
3668	for (bmp->db_agpref = 0; bmp->db_agpref < actags;
3669	bmp->db_agpref++) {
3670	if (bmp->db_agfree[bmp->db_agpref] >= avgfree)
3671	break;
3672	}
3673	if (bmp->db_agpref >= bmp->db_numag) {
3674	jfs_error(ipbmap->i_sb,
3675	"cannot find ag with average freespace\n");
3676	}
3677	}
3678
3679	/*
3680	* compute db_aglevel, db_agheight, db_width, db_agstart:
3681	* an ag is covered in aglevel dmapctl summary tree,
3682	* at agheight level height (from leaf) with agwidth number of nodes
3683	* each, which starts at agstart index node of the smmary tree node
3684	* array;
3685	*/
3686	bmp->db_aglevel = BMAPSZTOLEV(bmp->db_agsize);
3687	l2nl =
3688	bmp->db_agl2size - (L2BPERDMAP + bmp->db_aglevel * L2LPERCTL);
3689	bmp->db_agheight = l2nl >> 1;
3690	bmp->db_agwidth = 1 << (l2nl - (bmp->db_agheight << 1));
3691	for (i = 5 - bmp->db_agheight, bmp->db_agstart = 0, n = 1; i > 0;
3692	i--) {
3693	bmp->db_agstart += n;
3694	n <<= 2;
3695	}
3696
3697	}
3698
3699
3700	/*
3701	* NAME: dbInitDmap()/ujfs_idmap_page()
3702	*
3703	* FUNCTION: initialize working/persistent bitmap of the dmap page
3704	* for the specified number of blocks:
3705	*
3706	* at entry, the bitmaps had been initialized as free (ZEROS);
3707	* The number of blocks will only account for the actually
3708	* existing blocks. Blocks which don't actually exist in
3709	* the aggregate will be marked as allocated (ONES);
3710	*
3711	* PARAMETERS:
3712	* dp - pointer to page of map
3713	* nblocks - number of blocks this page
3714	*
3715	* RETURNS: NONE
3716	*/
3717	static int dbInitDmap(struct dmap * dp, s64 Blkno, int nblocks)
3718	{
3719	int blkno, w, b, r, nw, nb, i;
3720
3721	/* starting block number within the dmap */
3722	blkno = Blkno & (BPERDMAP - 1);
3723
3724	if (blkno == 0) {
3725	dp->nblocks = dp->nfree = cpu_to_le32(nblocks);
3726	dp->start = cpu_to_le64(Blkno);
3727
3728	if (nblocks == BPERDMAP) {
3729	memset(&dp->wmap[0], 0, LPERDMAP * 4);
3730	memset(&dp->pmap[0], 0, LPERDMAP * 4);
3731	goto initTree;
3732	}
3733	} else {
3734	le32_add_cpu(var: &dp->nblocks, val: nblocks);
3735	le32_add_cpu(var: &dp->nfree, val: nblocks);
3736	}
3737
3738	/* word number containing start block number */
3739	w = blkno >> L2DBWORD;
3740
3741	/*
3742	* free the bits corresponding to the block range (ZEROS):
3743	* note: not all bits of the first and last words may be contained
3744	* within the block range.
3745	*/
3746	for (r = nblocks; r > 0; r -= nb, blkno += nb) {
3747	/* number of bits preceding range to be freed in the word */
3748	b = blkno & (DBWORD - 1);
3749	/* number of bits to free in the word */
3750	nb = min(r, DBWORD - b);
3751
3752	/* is partial word to be freed ? */
3753	if (nb < DBWORD) {
3754	/* free (set to 0) from the bitmap word */
3755	dp->wmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3756	>> b));
3757	dp->pmap[w] &= cpu_to_le32(~(ONES << (DBWORD - nb)
3758	>> b));
3759
3760	/* skip the word freed */
3761	w++;
3762	} else {
3763	/* free (set to 0) contiguous bitmap words */
3764	nw = r >> L2DBWORD;
3765	memset(&dp->wmap[w], 0, nw * 4);
3766	memset(&dp->pmap[w], 0, nw * 4);
3767
3768	/* skip the words freed */
3769	nb = nw << L2DBWORD;
3770	w += nw;
3771	}
3772	}
3773
3774	/*
3775	* mark bits following the range to be freed (non-existing
3776	* blocks) as allocated (ONES)
3777	*/
3778
3779	if (blkno == BPERDMAP)
3780	goto initTree;
3781
3782	/* the first word beyond the end of existing blocks */
3783	w = blkno >> L2DBWORD;
3784
3785	/* does nblocks fall on a 32-bit boundary ? */
3786	b = blkno & (DBWORD - 1);
3787	if (b) {
3788	/* mark a partial word allocated */
3789	dp->wmap[w] = dp->pmap[w] = cpu_to_le32(ONES >> b);
3790	w++;
3791	}
3792
3793	/* set the rest of the words in the page to allocated (ONES) */
3794	for (i = w; i < LPERDMAP; i++)
3795	dp->pmap[i] = dp->wmap[i] = cpu_to_le32(ONES);
3796
3797	/*
3798	* init tree
3799	*/
3800	initTree:
3801	return (dbInitDmapTree(dp));
3802	}
3803
3804
3805	/*
3806	* NAME: dbInitDmapTree()/ujfs_complete_dmap()
3807	*
3808	* FUNCTION: initialize summary tree of the specified dmap:
3809	*
3810	* at entry, bitmap of the dmap has been initialized;
3811	*
3812	* PARAMETERS:
3813	* dp - dmap to complete
3814	* blkno - starting block number for this dmap
3815	* treemax - will be filled in with max free for this dmap
3816	*
3817	* RETURNS: max free string at the root of the tree
3818	*/
3819	static int dbInitDmapTree(struct dmap * dp)
3820	{
3821	struct dmaptree *tp;
3822	s8 *cp;
3823	int i;
3824
3825	/* init fixed info of tree */
3826	tp = &dp->tree;
3827	tp->nleafs = cpu_to_le32(LPERDMAP);
3828	tp->l2nleafs = cpu_to_le32(L2LPERDMAP);
3829	tp->leafidx = cpu_to_le32(LEAFIND);
3830	tp->height = cpu_to_le32(4);
3831	tp->budmin = BUDMIN;
3832
3833	/* init each leaf from corresponding wmap word:
3834	* note: leaf is set to NOFREE(-1) if all blocks of corresponding
3835	* bitmap word are allocated.
3836	*/
3837	cp = tp->stree + le32_to_cpu(tp->leafidx);
3838	for (i = 0; i < LPERDMAP; i++)
3839	*cp++ = dbMaxBud(cp: (u8 *) & dp->wmap[i]);
3840
3841	/* build the dmap's binary buddy summary tree */
3842	return (dbInitTree(dtp: tp));
3843	}
3844
3845
3846	/*
3847	* NAME: dbInitTree()/ujfs_adjtree()
3848	*
3849	* FUNCTION: initialize binary buddy summary tree of a dmap or dmapctl.
3850	*
3851	* at entry, the leaves of the tree has been initialized
3852	* from corresponding bitmap word or root of summary tree
3853	* of the child control page;
3854	* configure binary buddy system at the leaf level, then
3855	* bubble up the values of the leaf nodes up the tree.
3856	*
3857	* PARAMETERS:
3858	* cp - Pointer to the root of the tree
3859	* l2leaves- Number of leaf nodes as a power of 2
3860	* l2min - Number of blocks that can be covered by a leaf
3861	* as a power of 2
3862	*
3863	* RETURNS: max free string at the root of the tree
3864	*/
3865	static int dbInitTree(struct dmaptree * dtp)
3866	{
3867	int l2max, l2free, bsize, nextb, i;
3868	int child, parent, nparent;
3869	s8 *tp, *cp, *cp1;
3870
3871	tp = dtp->stree;
3872
3873	/* Determine the maximum free string possible for the leaves */
3874	l2max = le32_to_cpu(dtp->l2nleafs) + dtp->budmin;
3875
3876	/*
3877	* configure the leaf level into binary buddy system
3878	*
3879	* Try to combine buddies starting with a buddy size of 1
3880	* (i.e. two leaves). At a buddy size of 1 two buddy leaves
3881	* can be combined if both buddies have a maximum free of l2min;
3882	* the combination will result in the left-most buddy leaf having
3883	* a maximum free of l2min+1.
3884	* After processing all buddies for a given size, process buddies
3885	* at the next higher buddy size (i.e. current size * 2) and
3886	* the next maximum free (current free + 1).
3887	* This continues until the maximum possible buddy combination
3888	* yields maximum free.
3889	*/
3890	for (l2free = dtp->budmin, bsize = 1; l2free < l2max;
3891	l2free++, bsize = nextb) {
3892	/* get next buddy size == current buddy pair size */
3893	nextb = bsize << 1;
3894
3895	/* scan each adjacent buddy pair at current buddy size */
3896	for (i = 0, cp = tp + le32_to_cpu(dtp->leafidx);
3897	i < le32_to_cpu(dtp->nleafs);
3898	i += nextb, cp += nextb) {
3899	/* coalesce if both adjacent buddies are max free */
3900	if (*cp == l2free && *(cp + bsize) == l2free) {
3901	*cp = l2free + 1; /* left take right */
3902	*(cp + bsize) = -1; /* right give left */
3903	}
3904	}
3905	}
3906
3907	/*
3908	* bubble summary information of leaves up the tree.
3909	*
3910	* Starting at the leaf node level, the four nodes described by
3911	* the higher level parent node are compared for a maximum free and
3912	* this maximum becomes the value of the parent node.
3913	* when all lower level nodes are processed in this fashion then
3914	* move up to the next level (parent becomes a lower level node) and
3915	* continue the process for that level.
3916	*/
3917	for (child = le32_to_cpu(dtp->leafidx),
3918	nparent = le32_to_cpu(dtp->nleafs) >> 2;
3919	nparent > 0; nparent >>= 2, child = parent) {
3920	/* get index of 1st node of parent level */
3921	parent = (child - 1) >> 2;
3922
3923	/* set the value of the parent node as the maximum
3924	* of the four nodes of the current level.
3925	*/
3926	for (i = 0, cp = tp + child, cp1 = tp + parent;
3927	i < nparent; i++, cp += 4, cp1++)
3928	*cp1 = TREEMAX(cp);
3929	}
3930
3931	return (*tp);
3932	}
3933
3934
3935	/*
3936	* dbInitDmapCtl()
3937	*
3938	* function: initialize dmapctl page
3939	*/
3940	static int dbInitDmapCtl(struct dmapctl * dcp, int level, int i)
3941	{ /* start leaf index not covered by range */
3942	s8 *cp;
3943
3944	dcp->nleafs = cpu_to_le32(LPERCTL);
3945	dcp->l2nleafs = cpu_to_le32(L2LPERCTL);
3946	dcp->leafidx = cpu_to_le32(CTLLEAFIND);
3947	dcp->height = cpu_to_le32(5);
3948	dcp->budmin = L2BPERDMAP + L2LPERCTL * level;
3949
3950	/*
3951	* initialize the leaves of current level that were not covered
3952	* by the specified input block range (i.e. the leaves have no
3953	* low level dmapctl or dmap).
3954	*/
3955	cp = &dcp->stree[CTLLEAFIND + i];
3956	for (; i < LPERCTL; i++)
3957	*cp++ = NOFREE;
3958
3959	/* build the dmap's binary buddy summary tree */
3960	return (dbInitTree(dtp: (struct dmaptree *) dcp));
3961	}
3962
3963
3964	/*
3965	* NAME: dbGetL2AGSize()/ujfs_getagl2size()
3966	*
3967	* FUNCTION: Determine log2(allocation group size) from aggregate size
3968	*
3969	* PARAMETERS:
3970	* nblocks - Number of blocks in aggregate
3971	*
3972	* RETURNS: log2(allocation group size) in aggregate blocks
3973	*/
3974	static int dbGetL2AGSize(s64 nblocks)
3975	{
3976	s64 sz;
3977	s64 m;
3978	int l2sz;
3979
3980	if (nblocks < BPERDMAP * MAXAG)
3981	return (L2BPERDMAP);
3982
3983	/* round up aggregate size to power of 2 */
3984	m = ((u64) 1 << (64 - 1));
3985	for (l2sz = 64; l2sz >= 0; l2sz--, m >>= 1) {
3986	if (m & nblocks)
3987	break;
3988	}
3989
3990	sz = (s64) 1 << l2sz;
3991	if (sz < nblocks)
3992	l2sz += 1;
3993
3994	/* agsize = roundupSize/max_number_of_ag */
3995	return (l2sz - L2MAXAG);
3996	}
3997
3998
3999	/*
4000	* NAME: dbMapFileSizeToMapSize()
4001	*
4002	* FUNCTION: compute number of blocks the block allocation map file
4003	* can cover from the map file size;
4004	*
4005	* RETURNS: Number of blocks which can be covered by this block map file;
4006	*/
4007
4008	/*
4009	* maximum number of map pages at each level including control pages
4010	*/
4011	#define MAXL0PAGES (1 + LPERCTL)
4012	#define MAXL1PAGES (1 + LPERCTL * MAXL0PAGES)
4013
4014	/*
4015	* convert number of map pages to the zero origin top dmapctl level
4016	*/
4017	#define BMAPPGTOLEV(npages) \
4018	(((npages) <= 3 + MAXL0PAGES) ? 0 : \
4019	((npages) <= 2 + MAXL1PAGES) ? 1 : 2)
4020
4021	s64 dbMapFileSizeToMapSize(struct inode * ipbmap)
4022	{
4023	struct super_block *sb = ipbmap->i_sb;
4024	s64 nblocks;
4025	s64 npages, ndmaps;
4026	int level, i;
4027	int complete, factor;
4028
4029	nblocks = ipbmap->i_size >> JFS_SBI(sb)->l2bsize;
4030	npages = nblocks >> JFS_SBI(sb)->l2nbperpage;
4031	level = BMAPPGTOLEV(npages);
4032
4033	/* At each level, accumulate the number of dmap pages covered by
4034	* the number of full child levels below it;
4035	* repeat for the last incomplete child level.
4036	*/
4037	ndmaps = 0;
4038	npages--; /* skip the first global control page */
4039	/* skip higher level control pages above top level covered by map */
4040	npages -= (2 - level);
4041	npages--; /* skip top level's control page */
4042	for (i = level; i >= 0; i--) {
4043	factor =
4044	(i == 2) ? MAXL1PAGES : ((i == 1) ? MAXL0PAGES : 1);
4045	complete = (u32) npages / factor;
4046	ndmaps += complete * ((i == 2) ? LPERCTL * LPERCTL :
4047	((i == 1) ? LPERCTL : 1));
4048
4049	/* pages in last/incomplete child */
4050	npages = (u32) npages % factor;
4051	/* skip incomplete child's level control page */
4052	npages--;
4053	}
4054
4055	/* convert the number of dmaps into the number of blocks
4056	* which can be covered by the dmaps;
4057	*/
4058	nblocks = ndmaps << L2BPERDMAP;
4059
4060	return (nblocks);
4061	}
4062