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TOMOYO Linux Cross Reference
Linux/fs/jfs/jfs_metapage.c

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  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_status) {
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_status) {
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(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_set_dev(bio, 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                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
438 
439                 /* Don't call bio_add_page yet, we may add to this vec */
440                 bio_offset = offset;
441                 bio_bytes = len << inode->i_blkbits;
442 
443                 xlen -= len;
444                 next_block = lblock + len;
445         }
446         if (bio) {
447                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
448                                 goto add_failed;
449                 if (!bio->bi_iter.bi_size)
450                         goto dump_bio;
451 
452                 submit_bio(bio);
453                 nr_underway++;
454         }
455         if (redirty)
456                 redirty_page_for_writepage(wbc, page);
457 
458         unlock_page(page);
459 
460         if (bad_blocks)
461                 goto err_out;
462 
463         if (nr_underway == 0)
464                 end_page_writeback(page);
465 
466         return 0;
467 add_failed:
468         /* We should never reach here, since we're only adding one vec */
469         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
470         goto skip;
471 dump_bio:
472         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
473                        4, bio, sizeof(*bio), 0);
474 skip:
475         bio_put(bio);
476         unlock_page(page);
477         dec_io(page, last_write_complete);
478 err_out:
479         while (bad_blocks--)
480                 dec_io(page, last_write_complete);
481         return -EIO;
482 }
483 
484 static int metapage_readpage(struct file *fp, struct page *page)
485 {
486         struct inode *inode = page->mapping->host;
487         struct bio *bio = NULL;
488         int block_offset;
489         int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
490         sector_t page_start;    /* address of page in fs blocks */
491         sector_t pblock;
492         int xlen;
493         unsigned int len;
494         int offset;
495 
496         BUG_ON(!PageLocked(page));
497         page_start = (sector_t)page->index <<
498                      (PAGE_SHIFT - inode->i_blkbits);
499 
500         block_offset = 0;
501         while (block_offset < blocks_per_page) {
502                 xlen = blocks_per_page - block_offset;
503                 pblock = metapage_get_blocks(inode, page_start + block_offset,
504                                              &xlen);
505                 if (pblock) {
506                         if (!PagePrivate(page))
507                                 insert_metapage(page, NULL);
508                         inc_io(page);
509                         if (bio)
510                                 submit_bio(bio);
511 
512                         bio = bio_alloc(GFP_NOFS, 1);
513                         bio_set_dev(bio, inode->i_sb->s_bdev);
514                         bio->bi_iter.bi_sector =
515                                 pblock << (inode->i_blkbits - 9);
516                         bio->bi_end_io = metapage_read_end_io;
517                         bio->bi_private = page;
518                         bio_set_op_attrs(bio, REQ_OP_READ, 0);
519                         len = xlen << inode->i_blkbits;
520                         offset = block_offset << inode->i_blkbits;
521                         if (bio_add_page(bio, page, len, offset) < len)
522                                 goto add_failed;
523                         block_offset += xlen;
524                 } else
525                         block_offset++;
526         }
527         if (bio)
528                 submit_bio(bio);
529         else
530                 unlock_page(page);
531 
532         return 0;
533 
534 add_failed:
535         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
536         bio_put(bio);
537         dec_io(page, last_read_complete);
538         return -EIO;
539 }
540 
541 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
542 {
543         struct metapage *mp;
544         int ret = 1;
545         int offset;
546 
547         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
548                 mp = page_to_mp(page, offset);
549 
550                 if (!mp)
551                         continue;
552 
553                 jfs_info("metapage_releasepage: mp = 0x%p", mp);
554                 if (mp->count || mp->nohomeok ||
555                     test_bit(META_dirty, &mp->flag)) {
556                         jfs_info("count = %ld, nohomeok = %d", mp->count,
557                                  mp->nohomeok);
558                         ret = 0;
559                         continue;
560                 }
561                 if (mp->lsn)
562                         remove_from_logsync(mp);
563                 remove_metapage(page, mp);
564                 INCREMENT(mpStat.pagefree);
565                 free_metapage(mp);
566         }
567         return ret;
568 }
569 
570 static void metapage_invalidatepage(struct page *page, unsigned int offset,
571                                     unsigned int length)
572 {
573         BUG_ON(offset || length < PAGE_SIZE);
574 
575         BUG_ON(PageWriteback(page));
576 
577         metapage_releasepage(page, 0);
578 }
579 
580 const struct address_space_operations jfs_metapage_aops = {
581         .readpage       = metapage_readpage,
582         .writepage      = metapage_writepage,
583         .releasepage    = metapage_releasepage,
584         .invalidatepage = metapage_invalidatepage,
585         .set_page_dirty = __set_page_dirty_nobuffers,
586 };
587 
588 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
589                                 unsigned int size, int absolute,
590                                 unsigned long new)
591 {
592         int l2BlocksPerPage;
593         int l2bsize;
594         struct address_space *mapping;
595         struct metapage *mp = NULL;
596         struct page *page;
597         unsigned long page_index;
598         unsigned long page_offset;
599 
600         jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
601                  inode->i_ino, lblock, absolute);
602 
603         l2bsize = inode->i_blkbits;
604         l2BlocksPerPage = PAGE_SHIFT - l2bsize;
605         page_index = lblock >> l2BlocksPerPage;
606         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
607         if ((page_offset + size) > PAGE_SIZE) {
608                 jfs_err("MetaData crosses page boundary!!");
609                 jfs_err("lblock = %lx, size  = %d", lblock, size);
610                 dump_stack();
611                 return NULL;
612         }
613         if (absolute)
614                 mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
615         else {
616                 /*
617                  * If an nfs client tries to read an inode that is larger
618                  * than any existing inodes, we may try to read past the
619                  * end of the inode map
620                  */
621                 if ((lblock << inode->i_blkbits) >= inode->i_size)
622                         return NULL;
623                 mapping = inode->i_mapping;
624         }
625 
626         if (new && (PSIZE == PAGE_SIZE)) {
627                 page = grab_cache_page(mapping, page_index);
628                 if (!page) {
629                         jfs_err("grab_cache_page failed!");
630                         return NULL;
631                 }
632                 SetPageUptodate(page);
633         } else {
634                 page = read_mapping_page(mapping, page_index, NULL);
635                 if (IS_ERR(page) || !PageUptodate(page)) {
636                         jfs_err("read_mapping_page failed!");
637                         return NULL;
638                 }
639                 lock_page(page);
640         }
641 
642         mp = page_to_mp(page, page_offset);
643         if (mp) {
644                 if (mp->logical_size != size) {
645                         jfs_error(inode->i_sb,
646                                   "get_mp->logical_size != size\n");
647                         jfs_err("logical_size = %d, size = %d",
648                                 mp->logical_size, size);
649                         dump_stack();
650                         goto unlock;
651                 }
652                 mp->count++;
653                 lock_metapage(mp);
654                 if (test_bit(META_discard, &mp->flag)) {
655                         if (!new) {
656                                 jfs_error(inode->i_sb,
657                                           "using a discarded metapage\n");
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                 if (!mp)
667                         goto unlock;
668                 mp->page = page;
669                 mp->sb = inode->i_sb;
670                 mp->flag = 0;
671                 mp->xflag = COMMIT_PAGE;
672                 mp->count = 1;
673                 mp->nohomeok = 0;
674                 mp->logical_size = size;
675                 mp->data = page_address(page) + page_offset;
676                 mp->index = lblock;
677                 if (unlikely(insert_metapage(page, mp))) {
678                         free_metapage(mp);
679                         goto unlock;
680                 }
681                 lock_metapage(mp);
682         }
683 
684         if (new) {
685                 jfs_info("zeroing mp = 0x%p", mp);
686                 memset(mp->data, 0, PSIZE);
687         }
688 
689         unlock_page(page);
690         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
691         return mp;
692 
693 unlock:
694         unlock_page(page);
695         return NULL;
696 }
697 
698 void grab_metapage(struct metapage * mp)
699 {
700         jfs_info("grab_metapage: mp = 0x%p", mp);
701         get_page(mp->page);
702         lock_page(mp->page);
703         mp->count++;
704         lock_metapage(mp);
705         unlock_page(mp->page);
706 }
707 
708 void force_metapage(struct metapage *mp)
709 {
710         struct page *page = mp->page;
711         jfs_info("force_metapage: mp = 0x%p", mp);
712         set_bit(META_forcewrite, &mp->flag);
713         clear_bit(META_sync, &mp->flag);
714         get_page(page);
715         lock_page(page);
716         set_page_dirty(page);
717         if (write_one_page(page))
718                 jfs_error(mp->sb, "write_one_page() failed\n");
719         clear_bit(META_forcewrite, &mp->flag);
720         put_page(page);
721 }
722 
723 void hold_metapage(struct metapage *mp)
724 {
725         lock_page(mp->page);
726 }
727 
728 void put_metapage(struct metapage *mp)
729 {
730         if (mp->count || mp->nohomeok) {
731                 /* Someone else will release this */
732                 unlock_page(mp->page);
733                 return;
734         }
735         get_page(mp->page);
736         mp->count++;
737         lock_metapage(mp);
738         unlock_page(mp->page);
739         release_metapage(mp);
740 }
741 
742 void release_metapage(struct metapage * mp)
743 {
744         struct page *page = mp->page;
745         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
746 
747         BUG_ON(!page);
748 
749         lock_page(page);
750         unlock_metapage(mp);
751 
752         assert(mp->count);
753         if (--mp->count || mp->nohomeok) {
754                 unlock_page(page);
755                 put_page(page);
756                 return;
757         }
758 
759         if (test_bit(META_dirty, &mp->flag)) {
760                 set_page_dirty(page);
761                 if (test_bit(META_sync, &mp->flag)) {
762                         clear_bit(META_sync, &mp->flag);
763                         if (write_one_page(page))
764                                 jfs_error(mp->sb, "write_one_page() failed\n");
765                         lock_page(page); /* write_one_page unlocks the page */
766                 }
767         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
768                 remove_from_logsync(mp);
769 
770         /* Try to keep metapages from using up too much memory */
771         drop_metapage(page, mp);
772 
773         unlock_page(page);
774         put_page(page);
775 }
776 
777 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
778 {
779         sector_t lblock;
780         int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
781         int BlocksPerPage = 1 << l2BlocksPerPage;
782         /* All callers are interested in block device's mapping */
783         struct address_space *mapping =
784                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
785         struct metapage *mp;
786         struct page *page;
787         unsigned int offset;
788 
789         /*
790          * Mark metapages to discard.  They will eventually be
791          * released, but should not be written.
792          */
793         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
794              lblock += BlocksPerPage) {
795                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
796                 if (!page)
797                         continue;
798                 for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
799                         mp = page_to_mp(page, offset);
800                         if (!mp)
801                                 continue;
802                         if (mp->index < addr)
803                                 continue;
804                         if (mp->index >= addr + len)
805                                 break;
806 
807                         clear_bit(META_dirty, &mp->flag);
808                         set_bit(META_discard, &mp->flag);
809                         if (mp->lsn)
810                                 remove_from_logsync(mp);
811                 }
812                 unlock_page(page);
813                 put_page(page);
814         }
815 }
816 
817 #ifdef CONFIG_JFS_STATISTICS
818 int jfs_mpstat_proc_show(struct seq_file *m, void *v)
819 {
820         seq_printf(m,
821                        "JFS Metapage statistics\n"
822                        "=======================\n"
823                        "page allocations = %d\n"
824                        "page frees = %d\n"
825                        "lock waits = %d\n",
826                        mpStat.pagealloc,
827                        mpStat.pagefree,
828                        mpStat.lockwait);
829         return 0;
830 }
831 #endif
832 

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