xref: /openbmc/linux/fs/jfs/jfs_metapage.c (revision 64c70b1c)
1 /*
2  *   Copyright (C) International Business Machines Corp., 2000-2005
3  *   Portions Copyright (C) Christoph Hellwig, 2001-2002
4  *
5  *   This program is free software;  you can redistribute it and/or modify
6  *   it under the terms of the GNU General Public License as published by
7  *   the Free Software Foundation; either version 2 of the License, or
8  *   (at your option) any later version.
9  *
10  *   This program is distributed in the hope that it will be useful,
11  *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
13  *   the GNU General Public License for more details.
14  *
15  *   You should have received a copy of the GNU General Public License
16  *   along with this program;  if not, write to the Free Software
17  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  */
19 
20 #include <linux/fs.h>
21 #include <linux/mm.h>
22 #include <linux/bio.h>
23 #include <linux/init.h>
24 #include <linux/buffer_head.h>
25 #include <linux/mempool.h>
26 #include "jfs_incore.h"
27 #include "jfs_superblock.h"
28 #include "jfs_filsys.h"
29 #include "jfs_metapage.h"
30 #include "jfs_txnmgr.h"
31 #include "jfs_debug.h"
32 
33 #ifdef CONFIG_JFS_STATISTICS
34 static struct {
35 	uint	pagealloc;	/* # of page allocations */
36 	uint	pagefree;	/* # of page frees */
37 	uint	lockwait;	/* # of sleeping lock_metapage() calls */
38 } mpStat;
39 #endif
40 
41 #define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
42 #define trylock_metapage(mp) test_and_set_bit(META_locked, &(mp)->flag)
43 
44 static inline void unlock_metapage(struct metapage *mp)
45 {
46 	clear_bit(META_locked, &mp->flag);
47 	wake_up(&mp->wait);
48 }
49 
50 static inline void __lock_metapage(struct metapage *mp)
51 {
52 	DECLARE_WAITQUEUE(wait, current);
53 	INCREMENT(mpStat.lockwait);
54 	add_wait_queue_exclusive(&mp->wait, &wait);
55 	do {
56 		set_current_state(TASK_UNINTERRUPTIBLE);
57 		if (metapage_locked(mp)) {
58 			unlock_page(mp->page);
59 			io_schedule();
60 			lock_page(mp->page);
61 		}
62 	} while (trylock_metapage(mp));
63 	__set_current_state(TASK_RUNNING);
64 	remove_wait_queue(&mp->wait, &wait);
65 }
66 
67 /*
68  * Must have mp->page locked
69  */
70 static inline void lock_metapage(struct metapage *mp)
71 {
72 	if (trylock_metapage(mp))
73 		__lock_metapage(mp);
74 }
75 
76 #define METAPOOL_MIN_PAGES 32
77 static struct kmem_cache *metapage_cache;
78 static mempool_t *metapage_mempool;
79 
80 #define MPS_PER_PAGE (PAGE_CACHE_SIZE >> L2PSIZE)
81 
82 #if MPS_PER_PAGE > 1
83 
84 struct meta_anchor {
85 	int mp_count;
86 	atomic_t io_count;
87 	struct metapage *mp[MPS_PER_PAGE];
88 };
89 #define mp_anchor(page) ((struct meta_anchor *)page_private(page))
90 
91 static inline struct metapage *page_to_mp(struct page *page, uint offset)
92 {
93 	if (!PagePrivate(page))
94 		return NULL;
95 	return mp_anchor(page)->mp[offset >> L2PSIZE];
96 }
97 
98 static inline int insert_metapage(struct page *page, struct metapage *mp)
99 {
100 	struct meta_anchor *a;
101 	int index;
102 	int l2mp_blocks;	/* log2 blocks per metapage */
103 
104 	if (PagePrivate(page))
105 		a = mp_anchor(page);
106 	else {
107 		a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
108 		if (!a)
109 			return -ENOMEM;
110 		set_page_private(page, (unsigned long)a);
111 		SetPagePrivate(page);
112 		kmap(page);
113 	}
114 
115 	if (mp) {
116 		l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
117 		index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
118 		a->mp_count++;
119 		a->mp[index] = mp;
120 	}
121 
122 	return 0;
123 }
124 
125 static inline void remove_metapage(struct page *page, struct metapage *mp)
126 {
127 	struct meta_anchor *a = mp_anchor(page);
128 	int l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
129 	int index;
130 
131 	index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
132 
133 	BUG_ON(a->mp[index] != mp);
134 
135 	a->mp[index] = NULL;
136 	if (--a->mp_count == 0) {
137 		kfree(a);
138 		set_page_private(page, 0);
139 		ClearPagePrivate(page);
140 		kunmap(page);
141 	}
142 }
143 
144 static inline void inc_io(struct page *page)
145 {
146 	atomic_inc(&mp_anchor(page)->io_count);
147 }
148 
149 static inline void dec_io(struct page *page, void (*handler) (struct page *))
150 {
151 	if (atomic_dec_and_test(&mp_anchor(page)->io_count))
152 		handler(page);
153 }
154 
155 #else
156 static inline struct metapage *page_to_mp(struct page *page, uint offset)
157 {
158 	return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
159 }
160 
161 static inline int insert_metapage(struct page *page, struct metapage *mp)
162 {
163 	if (mp) {
164 		set_page_private(page, (unsigned long)mp);
165 		SetPagePrivate(page);
166 		kmap(page);
167 	}
168 	return 0;
169 }
170 
171 static inline void remove_metapage(struct page *page, struct metapage *mp)
172 {
173 	set_page_private(page, 0);
174 	ClearPagePrivate(page);
175 	kunmap(page);
176 }
177 
178 #define inc_io(page) do {} while(0)
179 #define dec_io(page, handler) handler(page)
180 
181 #endif
182 
183 static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags)
184 {
185 	struct metapage *mp = (struct metapage *)foo;
186 
187 	mp->lid = 0;
188 	mp->lsn = 0;
189 	mp->flag = 0;
190 	mp->data = NULL;
191 	mp->clsn = 0;
192 	mp->log = NULL;
193 	set_bit(META_free, &mp->flag);
194 	init_waitqueue_head(&mp->wait);
195 }
196 
197 static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
198 {
199 	return mempool_alloc(metapage_mempool, gfp_mask);
200 }
201 
202 static inline void free_metapage(struct metapage *mp)
203 {
204 	mp->flag = 0;
205 	set_bit(META_free, &mp->flag);
206 
207 	mempool_free(mp, metapage_mempool);
208 }
209 
210 int __init metapage_init(void)
211 {
212 	/*
213 	 * Allocate the metapage structures
214 	 */
215 	metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
216 					   0, 0, init_once, NULL);
217 	if (metapage_cache == NULL)
218 		return -ENOMEM;
219 
220 	metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
221 						    metapage_cache);
222 
223 	if (metapage_mempool == NULL) {
224 		kmem_cache_destroy(metapage_cache);
225 		return -ENOMEM;
226 	}
227 
228 	return 0;
229 }
230 
231 void metapage_exit(void)
232 {
233 	mempool_destroy(metapage_mempool);
234 	kmem_cache_destroy(metapage_cache);
235 }
236 
237 static inline void drop_metapage(struct page *page, struct metapage *mp)
238 {
239 	if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
240 	    test_bit(META_io, &mp->flag))
241 		return;
242 	remove_metapage(page, mp);
243 	INCREMENT(mpStat.pagefree);
244 	free_metapage(mp);
245 }
246 
247 /*
248  * Metapage address space operations
249  */
250 
251 static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
252 				    unsigned int *len)
253 {
254 	int rc = 0;
255 	int xflag;
256 	s64 xaddr;
257 	sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
258 			       inode->i_blkbits;
259 
260 	if (lblock >= file_blocks)
261 		return 0;
262 	if (lblock + *len > file_blocks)
263 		*len = file_blocks - lblock;
264 
265 	if (inode->i_ino) {
266 		rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
267 		if ((rc == 0) && *len)
268 			lblock = (sector_t)xaddr;
269 		else
270 			lblock = 0;
271 	} /* else no mapping */
272 
273 	return lblock;
274 }
275 
276 static void last_read_complete(struct page *page)
277 {
278 	if (!PageError(page))
279 		SetPageUptodate(page);
280 	unlock_page(page);
281 }
282 
283 static int metapage_read_end_io(struct bio *bio, unsigned int bytes_done,
284 				int err)
285 {
286 	struct page *page = bio->bi_private;
287 
288 	if (bio->bi_size)
289 		return 1;
290 
291 	if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
292 		printk(KERN_ERR "metapage_read_end_io: I/O error\n");
293 		SetPageError(page);
294 	}
295 
296 	dec_io(page, last_read_complete);
297 	bio_put(bio);
298 
299 	return 0;
300 }
301 
302 static void remove_from_logsync(struct metapage *mp)
303 {
304 	struct jfs_log *log = mp->log;
305 	unsigned long flags;
306 /*
307  * This can race.  Recheck that log hasn't been set to null, and after
308  * acquiring logsync lock, recheck lsn
309  */
310 	if (!log)
311 		return;
312 
313 	LOGSYNC_LOCK(log, flags);
314 	if (mp->lsn) {
315 		mp->log = NULL;
316 		mp->lsn = 0;
317 		mp->clsn = 0;
318 		log->count--;
319 		list_del(&mp->synclist);
320 	}
321 	LOGSYNC_UNLOCK(log, flags);
322 }
323 
324 static void last_write_complete(struct page *page)
325 {
326 	struct metapage *mp;
327 	unsigned int offset;
328 
329 	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
330 		mp = page_to_mp(page, offset);
331 		if (mp && test_bit(META_io, &mp->flag)) {
332 			if (mp->lsn)
333 				remove_from_logsync(mp);
334 			clear_bit(META_io, &mp->flag);
335 		}
336 		/*
337 		 * I'd like to call drop_metapage here, but I don't think it's
338 		 * safe unless I have the page locked
339 		 */
340 	}
341 	end_page_writeback(page);
342 }
343 
344 static int metapage_write_end_io(struct bio *bio, unsigned int bytes_done,
345 				 int err)
346 {
347 	struct page *page = bio->bi_private;
348 
349 	BUG_ON(!PagePrivate(page));
350 
351 	if (bio->bi_size)
352 		return 1;
353 
354 	if (! test_bit(BIO_UPTODATE, &bio->bi_flags)) {
355 		printk(KERN_ERR "metapage_write_end_io: I/O error\n");
356 		SetPageError(page);
357 	}
358 	dec_io(page, last_write_complete);
359 	bio_put(bio);
360 	return 0;
361 }
362 
363 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
364 {
365 	struct bio *bio = NULL;
366 	unsigned int block_offset;	/* block offset of mp within page */
367 	struct inode *inode = page->mapping->host;
368 	unsigned int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
369 	unsigned int len;
370 	unsigned int xlen;
371 	struct metapage *mp;
372 	int redirty = 0;
373 	sector_t lblock;
374 	sector_t pblock;
375 	sector_t next_block = 0;
376 	sector_t page_start;
377 	unsigned long bio_bytes = 0;
378 	unsigned long bio_offset = 0;
379 	unsigned int offset;
380 
381 	page_start = (sector_t)page->index <<
382 		     (PAGE_CACHE_SHIFT - inode->i_blkbits);
383 	BUG_ON(!PageLocked(page));
384 	BUG_ON(PageWriteback(page));
385 
386 	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
387 		mp = page_to_mp(page, offset);
388 
389 		if (!mp || !test_bit(META_dirty, &mp->flag))
390 			continue;
391 
392 		if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
393 			redirty = 1;
394 			/*
395 			 * Make sure this page isn't blocked indefinitely.
396 			 * If the journal isn't undergoing I/O, push it
397 			 */
398 			if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
399 				jfs_flush_journal(mp->log, 0);
400 			continue;
401 		}
402 
403 		clear_bit(META_dirty, &mp->flag);
404 		block_offset = offset >> inode->i_blkbits;
405 		lblock = page_start + block_offset;
406 		if (bio) {
407 			if (xlen && lblock == next_block) {
408 				/* Contiguous, in memory & on disk */
409 				len = min(xlen, blocks_per_mp);
410 				xlen -= len;
411 				bio_bytes += len << inode->i_blkbits;
412 				set_bit(META_io, &mp->flag);
413 				continue;
414 			}
415 			/* Not contiguous */
416 			if (bio_add_page(bio, page, bio_bytes, bio_offset) <
417 			    bio_bytes)
418 				goto add_failed;
419 			/*
420 			 * Increment counter before submitting i/o to keep
421 			 * count from hitting zero before we're through
422 			 */
423 			inc_io(page);
424 			if (!bio->bi_size)
425 				goto dump_bio;
426 			submit_bio(WRITE, bio);
427 			bio = NULL;
428 		} else {
429 			set_page_writeback(page);
430 			inc_io(page);
431 		}
432 		xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
433 		pblock = metapage_get_blocks(inode, lblock, &xlen);
434 		if (!pblock) {
435 			/* Need better error handling */
436 			printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
437 			dec_io(page, last_write_complete);
438 			continue;
439 		}
440 		set_bit(META_io, &mp->flag);
441 		len = min(xlen, (uint) JFS_SBI(inode->i_sb)->nbperpage);
442 
443 		bio = bio_alloc(GFP_NOFS, 1);
444 		bio->bi_bdev = inode->i_sb->s_bdev;
445 		bio->bi_sector = pblock << (inode->i_blkbits - 9);
446 		bio->bi_end_io = metapage_write_end_io;
447 		bio->bi_private = page;
448 
449 		/* Don't call bio_add_page yet, we may add to this vec */
450 		bio_offset = offset;
451 		bio_bytes = len << inode->i_blkbits;
452 
453 		xlen -= len;
454 		next_block = lblock + len;
455 	}
456 	if (bio) {
457 		if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
458 				goto add_failed;
459 		if (!bio->bi_size)
460 			goto dump_bio;
461 
462 		submit_bio(WRITE, bio);
463 	}
464 	if (redirty)
465 		redirty_page_for_writepage(wbc, page);
466 
467 	unlock_page(page);
468 
469 	return 0;
470 add_failed:
471 	/* We should never reach here, since we're only adding one vec */
472 	printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
473 	goto skip;
474 dump_bio:
475 	print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
476 		       4, bio, sizeof(*bio), 0);
477 skip:
478 	bio_put(bio);
479 	unlock_page(page);
480 	dec_io(page, last_write_complete);
481 
482 	return -EIO;
483 }
484 
485 static int metapage_readpage(struct file *fp, struct page *page)
486 {
487 	struct inode *inode = page->mapping->host;
488 	struct bio *bio = NULL;
489 	unsigned int block_offset;
490 	unsigned int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
491 	sector_t page_start;	/* address of page in fs blocks */
492 	sector_t pblock;
493 	unsigned int xlen;
494 	unsigned int len;
495 	unsigned int offset;
496 
497 	BUG_ON(!PageLocked(page));
498 	page_start = (sector_t)page->index <<
499 		     (PAGE_CACHE_SHIFT - inode->i_blkbits);
500 
501 	block_offset = 0;
502 	while (block_offset < blocks_per_page) {
503 		xlen = blocks_per_page - block_offset;
504 		pblock = metapage_get_blocks(inode, page_start + block_offset,
505 					     &xlen);
506 		if (pblock) {
507 			if (!PagePrivate(page))
508 				insert_metapage(page, NULL);
509 			inc_io(page);
510 			if (bio)
511 				submit_bio(READ, bio);
512 
513 			bio = bio_alloc(GFP_NOFS, 1);
514 			bio->bi_bdev = inode->i_sb->s_bdev;
515 			bio->bi_sector = pblock << (inode->i_blkbits - 9);
516 			bio->bi_end_io = metapage_read_end_io;
517 			bio->bi_private = page;
518 			len = xlen << inode->i_blkbits;
519 			offset = block_offset << inode->i_blkbits;
520 			if (bio_add_page(bio, page, len, offset) < len)
521 				goto add_failed;
522 			block_offset += xlen;
523 		} else
524 			block_offset++;
525 	}
526 	if (bio)
527 		submit_bio(READ, bio);
528 	else
529 		unlock_page(page);
530 
531 	return 0;
532 
533 add_failed:
534 	printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
535 	bio_put(bio);
536 	dec_io(page, last_read_complete);
537 	return -EIO;
538 }
539 
540 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
541 {
542 	struct metapage *mp;
543 	int ret = 1;
544 	unsigned int offset;
545 
546 	for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
547 		mp = page_to_mp(page, offset);
548 
549 		if (!mp)
550 			continue;
551 
552 		jfs_info("metapage_releasepage: mp = 0x%p", mp);
553 		if (mp->count || mp->nohomeok ||
554 		    test_bit(META_dirty, &mp->flag)) {
555 			jfs_info("count = %ld, nohomeok = %d", mp->count,
556 				 mp->nohomeok);
557 			ret = 0;
558 			continue;
559 		}
560 		if (mp->lsn)
561 			remove_from_logsync(mp);
562 		remove_metapage(page, mp);
563 		INCREMENT(mpStat.pagefree);
564 		free_metapage(mp);
565 	}
566 	return ret;
567 }
568 
569 static void metapage_invalidatepage(struct page *page, unsigned long offset)
570 {
571 	BUG_ON(offset);
572 
573 	BUG_ON(PageWriteback(page));
574 
575 	metapage_releasepage(page, 0);
576 }
577 
578 const struct address_space_operations jfs_metapage_aops = {
579 	.readpage	= metapage_readpage,
580 	.writepage	= metapage_writepage,
581 	.sync_page	= block_sync_page,
582 	.releasepage	= metapage_releasepage,
583 	.invalidatepage	= metapage_invalidatepage,
584 	.set_page_dirty	= __set_page_dirty_nobuffers,
585 };
586 
587 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
588 				unsigned int size, int absolute,
589 				unsigned long new)
590 {
591 	int l2BlocksPerPage;
592 	int l2bsize;
593 	struct address_space *mapping;
594 	struct metapage *mp = NULL;
595 	struct page *page;
596 	unsigned long page_index;
597 	unsigned long page_offset;
598 
599 	jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
600 		 inode->i_ino, lblock, absolute);
601 
602 	l2bsize = inode->i_blkbits;
603 	l2BlocksPerPage = PAGE_CACHE_SHIFT - l2bsize;
604 	page_index = lblock >> l2BlocksPerPage;
605 	page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
606 	if ((page_offset + size) > PAGE_CACHE_SIZE) {
607 		jfs_err("MetaData crosses page boundary!!");
608 		jfs_err("lblock = %lx, size  = %d", lblock, size);
609 		dump_stack();
610 		return NULL;
611 	}
612 	if (absolute)
613 		mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
614 	else {
615 		/*
616 		 * If an nfs client tries to read an inode that is larger
617 		 * than any existing inodes, we may try to read past the
618 		 * end of the inode map
619 		 */
620 		if ((lblock << inode->i_blkbits) >= inode->i_size)
621 			return NULL;
622 		mapping = inode->i_mapping;
623 	}
624 
625 	if (new && (PSIZE == PAGE_CACHE_SIZE)) {
626 		page = grab_cache_page(mapping, page_index);
627 		if (!page) {
628 			jfs_err("grab_cache_page failed!");
629 			return NULL;
630 		}
631 		SetPageUptodate(page);
632 	} else {
633 		page = read_mapping_page(mapping, page_index, NULL);
634 		if (IS_ERR(page) || !PageUptodate(page)) {
635 			jfs_err("read_mapping_page failed!");
636 			return NULL;
637 		}
638 		lock_page(page);
639 	}
640 
641 	mp = page_to_mp(page, page_offset);
642 	if (mp) {
643 		if (mp->logical_size != size) {
644 			jfs_error(inode->i_sb,
645 				  "__get_metapage: mp->logical_size != size");
646 			jfs_err("logical_size = %d, size = %d",
647 				mp->logical_size, size);
648 			dump_stack();
649 			goto unlock;
650 		}
651 		mp->count++;
652 		lock_metapage(mp);
653 		if (test_bit(META_discard, &mp->flag)) {
654 			if (!new) {
655 				jfs_error(inode->i_sb,
656 					  "__get_metapage: using a "
657 					  "discarded metapage");
658 				discard_metapage(mp);
659 				goto unlock;
660 			}
661 			clear_bit(META_discard, &mp->flag);
662 		}
663 	} else {
664 		INCREMENT(mpStat.pagealloc);
665 		mp = alloc_metapage(GFP_NOFS);
666 		mp->page = page;
667 		mp->flag = 0;
668 		mp->xflag = COMMIT_PAGE;
669 		mp->count = 1;
670 		mp->nohomeok = 0;
671 		mp->logical_size = size;
672 		mp->data = page_address(page) + page_offset;
673 		mp->index = lblock;
674 		if (unlikely(insert_metapage(page, mp))) {
675 			free_metapage(mp);
676 			goto unlock;
677 		}
678 		lock_metapage(mp);
679 	}
680 
681 	if (new) {
682 		jfs_info("zeroing mp = 0x%p", mp);
683 		memset(mp->data, 0, PSIZE);
684 	}
685 
686 	unlock_page(page);
687 	jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
688 	return mp;
689 
690 unlock:
691 	unlock_page(page);
692 	return NULL;
693 }
694 
695 void grab_metapage(struct metapage * mp)
696 {
697 	jfs_info("grab_metapage: mp = 0x%p", mp);
698 	page_cache_get(mp->page);
699 	lock_page(mp->page);
700 	mp->count++;
701 	lock_metapage(mp);
702 	unlock_page(mp->page);
703 }
704 
705 void force_metapage(struct metapage *mp)
706 {
707 	struct page *page = mp->page;
708 	jfs_info("force_metapage: mp = 0x%p", mp);
709 	set_bit(META_forcewrite, &mp->flag);
710 	clear_bit(META_sync, &mp->flag);
711 	page_cache_get(page);
712 	lock_page(page);
713 	set_page_dirty(page);
714 	write_one_page(page, 1);
715 	clear_bit(META_forcewrite, &mp->flag);
716 	page_cache_release(page);
717 }
718 
719 void hold_metapage(struct metapage *mp)
720 {
721 	lock_page(mp->page);
722 }
723 
724 void put_metapage(struct metapage *mp)
725 {
726 	if (mp->count || mp->nohomeok) {
727 		/* Someone else will release this */
728 		unlock_page(mp->page);
729 		return;
730 	}
731 	page_cache_get(mp->page);
732 	mp->count++;
733 	lock_metapage(mp);
734 	unlock_page(mp->page);
735 	release_metapage(mp);
736 }
737 
738 void release_metapage(struct metapage * mp)
739 {
740 	struct page *page = mp->page;
741 	jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
742 
743 	BUG_ON(!page);
744 
745 	lock_page(page);
746 	unlock_metapage(mp);
747 
748 	assert(mp->count);
749 	if (--mp->count || mp->nohomeok) {
750 		unlock_page(page);
751 		page_cache_release(page);
752 		return;
753 	}
754 
755 	if (test_bit(META_dirty, &mp->flag)) {
756 		set_page_dirty(page);
757 		if (test_bit(META_sync, &mp->flag)) {
758 			clear_bit(META_sync, &mp->flag);
759 			write_one_page(page, 1);
760 			lock_page(page); /* write_one_page unlocks the page */
761 		}
762 	} else if (mp->lsn)	/* discard_metapage doesn't remove it */
763 		remove_from_logsync(mp);
764 
765 	/* Try to keep metapages from using up too much memory */
766 	drop_metapage(page, mp);
767 
768 	unlock_page(page);
769 	page_cache_release(page);
770 }
771 
772 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
773 {
774 	sector_t lblock;
775 	int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
776 	int BlocksPerPage = 1 << l2BlocksPerPage;
777 	/* All callers are interested in block device's mapping */
778 	struct address_space *mapping =
779 		JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
780 	struct metapage *mp;
781 	struct page *page;
782 	unsigned int offset;
783 
784 	/*
785 	 * Mark metapages to discard.  They will eventually be
786 	 * released, but should not be written.
787 	 */
788 	for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
789 	     lblock += BlocksPerPage) {
790 		page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
791 		if (!page)
792 			continue;
793 		for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
794 			mp = page_to_mp(page, offset);
795 			if (!mp)
796 				continue;
797 			if (mp->index < addr)
798 				continue;
799 			if (mp->index >= addr + len)
800 				break;
801 
802 			clear_bit(META_dirty, &mp->flag);
803 			set_bit(META_discard, &mp->flag);
804 			if (mp->lsn)
805 				remove_from_logsync(mp);
806 		}
807 		unlock_page(page);
808 		page_cache_release(page);
809 	}
810 }
811 
812 #ifdef CONFIG_JFS_STATISTICS
813 int jfs_mpstat_read(char *buffer, char **start, off_t offset, int length,
814 		    int *eof, void *data)
815 {
816 	int len = 0;
817 	off_t begin;
818 
819 	len += sprintf(buffer,
820 		       "JFS Metapage statistics\n"
821 		       "=======================\n"
822 		       "page allocations = %d\n"
823 		       "page frees = %d\n"
824 		       "lock waits = %d\n",
825 		       mpStat.pagealloc,
826 		       mpStat.pagefree,
827 		       mpStat.lockwait);
828 
829 	begin = offset;
830 	*start = buffer + begin;
831 	len -= begin;
832 
833 	if (len > length)
834 		len = length;
835 	else
836 		*eof = 1;
837 
838 	if (len < 0)
839 		len = 0;
840 
841 	return len;
842 }
843 #endif
844