xref: /openbmc/linux/fs/jfs/jfs_metapage.c (revision 0edbfea5)
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/module.h>
23 #include <linux/bio.h>
24 #include <linux/slab.h>
25 #include <linux/init.h>
26 #include <linux/buffer_head.h>
27 #include <linux/mempool.h>
28 #include <linux/seq_file.h>
29 #include "jfs_incore.h"
30 #include "jfs_superblock.h"
31 #include "jfs_filsys.h"
32 #include "jfs_metapage.h"
33 #include "jfs_txnmgr.h"
34 #include "jfs_debug.h"
35 
36 #ifdef CONFIG_JFS_STATISTICS
37 static struct {
38 	uint	pagealloc;	/* # of page allocations */
39 	uint	pagefree;	/* # of page frees */
40 	uint	lockwait;	/* # of sleeping lock_metapage() calls */
41 } mpStat;
42 #endif
43 
44 #define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
45 #define trylock_metapage(mp) test_and_set_bit_lock(META_locked, &(mp)->flag)
46 
47 static inline void unlock_metapage(struct metapage *mp)
48 {
49 	clear_bit_unlock(META_locked, &mp->flag);
50 	wake_up(&mp->wait);
51 }
52 
53 static inline void __lock_metapage(struct metapage *mp)
54 {
55 	DECLARE_WAITQUEUE(wait, current);
56 	INCREMENT(mpStat.lockwait);
57 	add_wait_queue_exclusive(&mp->wait, &wait);
58 	do {
59 		set_current_state(TASK_UNINTERRUPTIBLE);
60 		if (metapage_locked(mp)) {
61 			unlock_page(mp->page);
62 			io_schedule();
63 			lock_page(mp->page);
64 		}
65 	} while (trylock_metapage(mp));
66 	__set_current_state(TASK_RUNNING);
67 	remove_wait_queue(&mp->wait, &wait);
68 }
69 
70 /*
71  * Must have mp->page locked
72  */
73 static inline void lock_metapage(struct metapage *mp)
74 {
75 	if (trylock_metapage(mp))
76 		__lock_metapage(mp);
77 }
78 
79 #define METAPOOL_MIN_PAGES 32
80 static struct kmem_cache *metapage_cache;
81 static mempool_t *metapage_mempool;
82 
83 #define MPS_PER_PAGE (PAGE_SIZE >> L2PSIZE)
84 
85 #if MPS_PER_PAGE > 1
86 
87 struct meta_anchor {
88 	int mp_count;
89 	atomic_t io_count;
90 	struct metapage *mp[MPS_PER_PAGE];
91 };
92 #define mp_anchor(page) ((struct meta_anchor *)page_private(page))
93 
94 static inline struct metapage *page_to_mp(struct page *page, int offset)
95 {
96 	if (!PagePrivate(page))
97 		return NULL;
98 	return mp_anchor(page)->mp[offset >> L2PSIZE];
99 }
100 
101 static inline int insert_metapage(struct page *page, struct metapage *mp)
102 {
103 	struct meta_anchor *a;
104 	int index;
105 	int l2mp_blocks;	/* log2 blocks per metapage */
106 
107 	if (PagePrivate(page))
108 		a = mp_anchor(page);
109 	else {
110 		a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
111 		if (!a)
112 			return -ENOMEM;
113 		set_page_private(page, (unsigned long)a);
114 		SetPagePrivate(page);
115 		kmap(page);
116 	}
117 
118 	if (mp) {
119 		l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
120 		index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
121 		a->mp_count++;
122 		a->mp[index] = mp;
123 	}
124 
125 	return 0;
126 }
127 
128 static inline void remove_metapage(struct page *page, struct metapage *mp)
129 {
130 	struct meta_anchor *a = mp_anchor(page);
131 	int l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
132 	int index;
133 
134 	index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
135 
136 	BUG_ON(a->mp[index] != mp);
137 
138 	a->mp[index] = NULL;
139 	if (--a->mp_count == 0) {
140 		kfree(a);
141 		set_page_private(page, 0);
142 		ClearPagePrivate(page);
143 		kunmap(page);
144 	}
145 }
146 
147 static inline void inc_io(struct page *page)
148 {
149 	atomic_inc(&mp_anchor(page)->io_count);
150 }
151 
152 static inline void dec_io(struct page *page, void (*handler) (struct page *))
153 {
154 	if (atomic_dec_and_test(&mp_anchor(page)->io_count))
155 		handler(page);
156 }
157 
158 #else
159 static inline struct metapage *page_to_mp(struct page *page, int offset)
160 {
161 	return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
162 }
163 
164 static inline int insert_metapage(struct page *page, struct metapage *mp)
165 {
166 	if (mp) {
167 		set_page_private(page, (unsigned long)mp);
168 		SetPagePrivate(page);
169 		kmap(page);
170 	}
171 	return 0;
172 }
173 
174 static inline void remove_metapage(struct page *page, struct metapage *mp)
175 {
176 	set_page_private(page, 0);
177 	ClearPagePrivate(page);
178 	kunmap(page);
179 }
180 
181 #define inc_io(page) do {} while(0)
182 #define dec_io(page, handler) handler(page)
183 
184 #endif
185 
186 static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
187 {
188 	struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
189 
190 	if (mp) {
191 		mp->lid = 0;
192 		mp->lsn = 0;
193 		mp->data = NULL;
194 		mp->clsn = 0;
195 		mp->log = NULL;
196 		init_waitqueue_head(&mp->wait);
197 	}
198 	return mp;
199 }
200 
201 static inline void free_metapage(struct metapage *mp)
202 {
203 	mempool_free(mp, metapage_mempool);
204 }
205 
206 int __init metapage_init(void)
207 {
208 	/*
209 	 * Allocate the metapage structures
210 	 */
211 	metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
212 					   0, 0, NULL);
213 	if (metapage_cache == NULL)
214 		return -ENOMEM;
215 
216 	metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
217 						    metapage_cache);
218 
219 	if (metapage_mempool == NULL) {
220 		kmem_cache_destroy(metapage_cache);
221 		return -ENOMEM;
222 	}
223 
224 	return 0;
225 }
226 
227 void metapage_exit(void)
228 {
229 	mempool_destroy(metapage_mempool);
230 	kmem_cache_destroy(metapage_cache);
231 }
232 
233 static inline void drop_metapage(struct page *page, struct metapage *mp)
234 {
235 	if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
236 	    test_bit(META_io, &mp->flag))
237 		return;
238 	remove_metapage(page, mp);
239 	INCREMENT(mpStat.pagefree);
240 	free_metapage(mp);
241 }
242 
243 /*
244  * Metapage address space operations
245  */
246 
247 static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
248 				    int *len)
249 {
250 	int rc = 0;
251 	int xflag;
252 	s64 xaddr;
253 	sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
254 			       inode->i_blkbits;
255 
256 	if (lblock >= file_blocks)
257 		return 0;
258 	if (lblock + *len > file_blocks)
259 		*len = file_blocks - lblock;
260 
261 	if (inode->i_ino) {
262 		rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
263 		if ((rc == 0) && *len)
264 			lblock = (sector_t)xaddr;
265 		else
266 			lblock = 0;
267 	} /* else no mapping */
268 
269 	return lblock;
270 }
271 
272 static void last_read_complete(struct page *page)
273 {
274 	if (!PageError(page))
275 		SetPageUptodate(page);
276 	unlock_page(page);
277 }
278 
279 static void metapage_read_end_io(struct bio *bio)
280 {
281 	struct page *page = bio->bi_private;
282 
283 	if (bio->bi_error) {
284 		printk(KERN_ERR "metapage_read_end_io: I/O error\n");
285 		SetPageError(page);
286 	}
287 
288 	dec_io(page, last_read_complete);
289 	bio_put(bio);
290 }
291 
292 static void remove_from_logsync(struct metapage *mp)
293 {
294 	struct jfs_log *log = mp->log;
295 	unsigned long flags;
296 /*
297  * This can race.  Recheck that log hasn't been set to null, and after
298  * acquiring logsync lock, recheck lsn
299  */
300 	if (!log)
301 		return;
302 
303 	LOGSYNC_LOCK(log, flags);
304 	if (mp->lsn) {
305 		mp->log = NULL;
306 		mp->lsn = 0;
307 		mp->clsn = 0;
308 		log->count--;
309 		list_del(&mp->synclist);
310 	}
311 	LOGSYNC_UNLOCK(log, flags);
312 }
313 
314 static void last_write_complete(struct page *page)
315 {
316 	struct metapage *mp;
317 	unsigned int offset;
318 
319 	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
320 		mp = page_to_mp(page, offset);
321 		if (mp && test_bit(META_io, &mp->flag)) {
322 			if (mp->lsn)
323 				remove_from_logsync(mp);
324 			clear_bit(META_io, &mp->flag);
325 		}
326 		/*
327 		 * I'd like to call drop_metapage here, but I don't think it's
328 		 * safe unless I have the page locked
329 		 */
330 	}
331 	end_page_writeback(page);
332 }
333 
334 static void metapage_write_end_io(struct bio *bio)
335 {
336 	struct page *page = bio->bi_private;
337 
338 	BUG_ON(!PagePrivate(page));
339 
340 	if (bio->bi_error) {
341 		printk(KERN_ERR "metapage_write_end_io: I/O error\n");
342 		SetPageError(page);
343 	}
344 	dec_io(page, last_write_complete);
345 	bio_put(bio);
346 }
347 
348 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
349 {
350 	struct bio *bio = NULL;
351 	int block_offset;	/* block offset of mp within page */
352 	struct inode *inode = page->mapping->host;
353 	int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
354 	int len;
355 	int xlen;
356 	struct metapage *mp;
357 	int redirty = 0;
358 	sector_t lblock;
359 	int nr_underway = 0;
360 	sector_t pblock;
361 	sector_t next_block = 0;
362 	sector_t page_start;
363 	unsigned long bio_bytes = 0;
364 	unsigned long bio_offset = 0;
365 	int offset;
366 	int bad_blocks = 0;
367 
368 	page_start = (sector_t)page->index <<
369 		     (PAGE_SHIFT - inode->i_blkbits);
370 	BUG_ON(!PageLocked(page));
371 	BUG_ON(PageWriteback(page));
372 	set_page_writeback(page);
373 
374 	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
375 		mp = page_to_mp(page, offset);
376 
377 		if (!mp || !test_bit(META_dirty, &mp->flag))
378 			continue;
379 
380 		if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
381 			redirty = 1;
382 			/*
383 			 * Make sure this page isn't blocked indefinitely.
384 			 * If the journal isn't undergoing I/O, push it
385 			 */
386 			if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
387 				jfs_flush_journal(mp->log, 0);
388 			continue;
389 		}
390 
391 		clear_bit(META_dirty, &mp->flag);
392 		set_bit(META_io, &mp->flag);
393 		block_offset = offset >> inode->i_blkbits;
394 		lblock = page_start + block_offset;
395 		if (bio) {
396 			if (xlen && lblock == next_block) {
397 				/* Contiguous, in memory & on disk */
398 				len = min(xlen, blocks_per_mp);
399 				xlen -= len;
400 				bio_bytes += len << inode->i_blkbits;
401 				continue;
402 			}
403 			/* Not contiguous */
404 			if (bio_add_page(bio, page, bio_bytes, bio_offset) <
405 			    bio_bytes)
406 				goto add_failed;
407 			/*
408 			 * Increment counter before submitting i/o to keep
409 			 * count from hitting zero before we're through
410 			 */
411 			inc_io(page);
412 			if (!bio->bi_iter.bi_size)
413 				goto dump_bio;
414 			submit_bio(WRITE, bio);
415 			nr_underway++;
416 			bio = NULL;
417 		} else
418 			inc_io(page);
419 		xlen = (PAGE_SIZE - offset) >> inode->i_blkbits;
420 		pblock = metapage_get_blocks(inode, lblock, &xlen);
421 		if (!pblock) {
422 			printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
423 			/*
424 			 * We already called inc_io(), but can't cancel it
425 			 * with dec_io() until we're done with the page
426 			 */
427 			bad_blocks++;
428 			continue;
429 		}
430 		len = min(xlen, (int)JFS_SBI(inode->i_sb)->nbperpage);
431 
432 		bio = bio_alloc(GFP_NOFS, 1);
433 		bio->bi_bdev = inode->i_sb->s_bdev;
434 		bio->bi_iter.bi_sector = pblock << (inode->i_blkbits - 9);
435 		bio->bi_end_io = metapage_write_end_io;
436 		bio->bi_private = page;
437 
438 		/* Don't call bio_add_page yet, we may add to this vec */
439 		bio_offset = offset;
440 		bio_bytes = len << inode->i_blkbits;
441 
442 		xlen -= len;
443 		next_block = lblock + len;
444 	}
445 	if (bio) {
446 		if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
447 				goto add_failed;
448 		if (!bio->bi_iter.bi_size)
449 			goto dump_bio;
450 
451 		submit_bio(WRITE, bio);
452 		nr_underway++;
453 	}
454 	if (redirty)
455 		redirty_page_for_writepage(wbc, page);
456 
457 	unlock_page(page);
458 
459 	if (bad_blocks)
460 		goto err_out;
461 
462 	if (nr_underway == 0)
463 		end_page_writeback(page);
464 
465 	return 0;
466 add_failed:
467 	/* We should never reach here, since we're only adding one vec */
468 	printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
469 	goto skip;
470 dump_bio:
471 	print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
472 		       4, bio, sizeof(*bio), 0);
473 skip:
474 	bio_put(bio);
475 	unlock_page(page);
476 	dec_io(page, last_write_complete);
477 err_out:
478 	while (bad_blocks--)
479 		dec_io(page, last_write_complete);
480 	return -EIO;
481 }
482 
483 static int metapage_readpage(struct file *fp, struct page *page)
484 {
485 	struct inode *inode = page->mapping->host;
486 	struct bio *bio = NULL;
487 	int block_offset;
488 	int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
489 	sector_t page_start;	/* address of page in fs blocks */
490 	sector_t pblock;
491 	int xlen;
492 	unsigned int len;
493 	int offset;
494 
495 	BUG_ON(!PageLocked(page));
496 	page_start = (sector_t)page->index <<
497 		     (PAGE_SHIFT - inode->i_blkbits);
498 
499 	block_offset = 0;
500 	while (block_offset < blocks_per_page) {
501 		xlen = blocks_per_page - block_offset;
502 		pblock = metapage_get_blocks(inode, page_start + block_offset,
503 					     &xlen);
504 		if (pblock) {
505 			if (!PagePrivate(page))
506 				insert_metapage(page, NULL);
507 			inc_io(page);
508 			if (bio)
509 				submit_bio(READ, bio);
510 
511 			bio = bio_alloc(GFP_NOFS, 1);
512 			bio->bi_bdev = inode->i_sb->s_bdev;
513 			bio->bi_iter.bi_sector =
514 				pblock << (inode->i_blkbits - 9);
515 			bio->bi_end_io = metapage_read_end_io;
516 			bio->bi_private = page;
517 			len = xlen << inode->i_blkbits;
518 			offset = block_offset << inode->i_blkbits;
519 			if (bio_add_page(bio, page, len, offset) < len)
520 				goto add_failed;
521 			block_offset += xlen;
522 		} else
523 			block_offset++;
524 	}
525 	if (bio)
526 		submit_bio(READ, bio);
527 	else
528 		unlock_page(page);
529 
530 	return 0;
531 
532 add_failed:
533 	printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
534 	bio_put(bio);
535 	dec_io(page, last_read_complete);
536 	return -EIO;
537 }
538 
539 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
540 {
541 	struct metapage *mp;
542 	int ret = 1;
543 	int offset;
544 
545 	for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
546 		mp = page_to_mp(page, offset);
547 
548 		if (!mp)
549 			continue;
550 
551 		jfs_info("metapage_releasepage: mp = 0x%p", mp);
552 		if (mp->count || mp->nohomeok ||
553 		    test_bit(META_dirty, &mp->flag)) {
554 			jfs_info("count = %ld, nohomeok = %d", mp->count,
555 				 mp->nohomeok);
556 			ret = 0;
557 			continue;
558 		}
559 		if (mp->lsn)
560 			remove_from_logsync(mp);
561 		remove_metapage(page, mp);
562 		INCREMENT(mpStat.pagefree);
563 		free_metapage(mp);
564 	}
565 	return ret;
566 }
567 
568 static void metapage_invalidatepage(struct page *page, unsigned int offset,
569 				    unsigned int length)
570 {
571 	BUG_ON(offset || length < PAGE_SIZE);
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 	.releasepage	= metapage_releasepage,
582 	.invalidatepage	= metapage_invalidatepage,
583 	.set_page_dirty	= __set_page_dirty_nobuffers,
584 };
585 
586 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
587 				unsigned int size, int absolute,
588 				unsigned long new)
589 {
590 	int l2BlocksPerPage;
591 	int l2bsize;
592 	struct address_space *mapping;
593 	struct metapage *mp = NULL;
594 	struct page *page;
595 	unsigned long page_index;
596 	unsigned long page_offset;
597 
598 	jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
599 		 inode->i_ino, lblock, absolute);
600 
601 	l2bsize = inode->i_blkbits;
602 	l2BlocksPerPage = PAGE_SHIFT - l2bsize;
603 	page_index = lblock >> l2BlocksPerPage;
604 	page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
605 	if ((page_offset + size) > PAGE_SIZE) {
606 		jfs_err("MetaData crosses page boundary!!");
607 		jfs_err("lblock = %lx, size  = %d", lblock, size);
608 		dump_stack();
609 		return NULL;
610 	}
611 	if (absolute)
612 		mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
613 	else {
614 		/*
615 		 * If an nfs client tries to read an inode that is larger
616 		 * than any existing inodes, we may try to read past the
617 		 * end of the inode map
618 		 */
619 		if ((lblock << inode->i_blkbits) >= inode->i_size)
620 			return NULL;
621 		mapping = inode->i_mapping;
622 	}
623 
624 	if (new && (PSIZE == PAGE_SIZE)) {
625 		page = grab_cache_page(mapping, page_index);
626 		if (!page) {
627 			jfs_err("grab_cache_page failed!");
628 			return NULL;
629 		}
630 		SetPageUptodate(page);
631 	} else {
632 		page = read_mapping_page(mapping, page_index, NULL);
633 		if (IS_ERR(page) || !PageUptodate(page)) {
634 			jfs_err("read_mapping_page failed!");
635 			return NULL;
636 		}
637 		lock_page(page);
638 	}
639 
640 	mp = page_to_mp(page, page_offset);
641 	if (mp) {
642 		if (mp->logical_size != size) {
643 			jfs_error(inode->i_sb,
644 				  "get_mp->logical_size != size\n");
645 			jfs_err("logical_size = %d, size = %d",
646 				mp->logical_size, size);
647 			dump_stack();
648 			goto unlock;
649 		}
650 		mp->count++;
651 		lock_metapage(mp);
652 		if (test_bit(META_discard, &mp->flag)) {
653 			if (!new) {
654 				jfs_error(inode->i_sb,
655 					  "using a discarded metapage\n");
656 				discard_metapage(mp);
657 				goto unlock;
658 			}
659 			clear_bit(META_discard, &mp->flag);
660 		}
661 	} else {
662 		INCREMENT(mpStat.pagealloc);
663 		mp = alloc_metapage(GFP_NOFS);
664 		mp->page = page;
665 		mp->flag = 0;
666 		mp->xflag = COMMIT_PAGE;
667 		mp->count = 1;
668 		mp->nohomeok = 0;
669 		mp->logical_size = size;
670 		mp->data = page_address(page) + page_offset;
671 		mp->index = lblock;
672 		if (unlikely(insert_metapage(page, mp))) {
673 			free_metapage(mp);
674 			goto unlock;
675 		}
676 		lock_metapage(mp);
677 	}
678 
679 	if (new) {
680 		jfs_info("zeroing mp = 0x%p", mp);
681 		memset(mp->data, 0, PSIZE);
682 	}
683 
684 	unlock_page(page);
685 	jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
686 	return mp;
687 
688 unlock:
689 	unlock_page(page);
690 	return NULL;
691 }
692 
693 void grab_metapage(struct metapage * mp)
694 {
695 	jfs_info("grab_metapage: mp = 0x%p", mp);
696 	get_page(mp->page);
697 	lock_page(mp->page);
698 	mp->count++;
699 	lock_metapage(mp);
700 	unlock_page(mp->page);
701 }
702 
703 void force_metapage(struct metapage *mp)
704 {
705 	struct page *page = mp->page;
706 	jfs_info("force_metapage: mp = 0x%p", mp);
707 	set_bit(META_forcewrite, &mp->flag);
708 	clear_bit(META_sync, &mp->flag);
709 	get_page(page);
710 	lock_page(page);
711 	set_page_dirty(page);
712 	write_one_page(page, 1);
713 	clear_bit(META_forcewrite, &mp->flag);
714 	put_page(page);
715 }
716 
717 void hold_metapage(struct metapage *mp)
718 {
719 	lock_page(mp->page);
720 }
721 
722 void put_metapage(struct metapage *mp)
723 {
724 	if (mp->count || mp->nohomeok) {
725 		/* Someone else will release this */
726 		unlock_page(mp->page);
727 		return;
728 	}
729 	get_page(mp->page);
730 	mp->count++;
731 	lock_metapage(mp);
732 	unlock_page(mp->page);
733 	release_metapage(mp);
734 }
735 
736 void release_metapage(struct metapage * mp)
737 {
738 	struct page *page = mp->page;
739 	jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
740 
741 	BUG_ON(!page);
742 
743 	lock_page(page);
744 	unlock_metapage(mp);
745 
746 	assert(mp->count);
747 	if (--mp->count || mp->nohomeok) {
748 		unlock_page(page);
749 		put_page(page);
750 		return;
751 	}
752 
753 	if (test_bit(META_dirty, &mp->flag)) {
754 		set_page_dirty(page);
755 		if (test_bit(META_sync, &mp->flag)) {
756 			clear_bit(META_sync, &mp->flag);
757 			write_one_page(page, 1);
758 			lock_page(page); /* write_one_page unlocks the page */
759 		}
760 	} else if (mp->lsn)	/* discard_metapage doesn't remove it */
761 		remove_from_logsync(mp);
762 
763 	/* Try to keep metapages from using up too much memory */
764 	drop_metapage(page, mp);
765 
766 	unlock_page(page);
767 	put_page(page);
768 }
769 
770 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
771 {
772 	sector_t lblock;
773 	int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
774 	int BlocksPerPage = 1 << l2BlocksPerPage;
775 	/* All callers are interested in block device's mapping */
776 	struct address_space *mapping =
777 		JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
778 	struct metapage *mp;
779 	struct page *page;
780 	unsigned int offset;
781 
782 	/*
783 	 * Mark metapages to discard.  They will eventually be
784 	 * released, but should not be written.
785 	 */
786 	for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
787 	     lblock += BlocksPerPage) {
788 		page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
789 		if (!page)
790 			continue;
791 		for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
792 			mp = page_to_mp(page, offset);
793 			if (!mp)
794 				continue;
795 			if (mp->index < addr)
796 				continue;
797 			if (mp->index >= addr + len)
798 				break;
799 
800 			clear_bit(META_dirty, &mp->flag);
801 			set_bit(META_discard, &mp->flag);
802 			if (mp->lsn)
803 				remove_from_logsync(mp);
804 		}
805 		unlock_page(page);
806 		put_page(page);
807 	}
808 }
809 
810 #ifdef CONFIG_JFS_STATISTICS
811 static int jfs_mpstat_proc_show(struct seq_file *m, void *v)
812 {
813 	seq_printf(m,
814 		       "JFS Metapage statistics\n"
815 		       "=======================\n"
816 		       "page allocations = %d\n"
817 		       "page frees = %d\n"
818 		       "lock waits = %d\n",
819 		       mpStat.pagealloc,
820 		       mpStat.pagefree,
821 		       mpStat.lockwait);
822 	return 0;
823 }
824 
825 static int jfs_mpstat_proc_open(struct inode *inode, struct file *file)
826 {
827 	return single_open(file, jfs_mpstat_proc_show, NULL);
828 }
829 
830 const struct file_operations jfs_mpstat_proc_fops = {
831 	.owner		= THIS_MODULE,
832 	.open		= jfs_mpstat_proc_open,
833 	.read		= seq_read,
834 	.llseek		= seq_lseek,
835 	.release	= single_release,
836 };
837 #endif
838