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Linux/fs/jfs/jfs_metapage.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  *   Copyright (C) International Business Machines Corp., 2000-2005
  4  *   Portions Copyright (C) Christoph Hellwig, 2001-2002
  5  */
  6 
  7 #include <linux/fs.h>
  8 #include <linux/mm.h>
  9 #include <linux/module.h>
 10 #include <linux/bio.h>
 11 #include <linux/slab.h>
 12 #include <linux/init.h>
 13 #include <linux/buffer_head.h>
 14 #include <linux/mempool.h>
 15 #include <linux/seq_file.h>
 16 #include <linux/writeback.h>
 17 #include "jfs_incore.h"
 18 #include "jfs_superblock.h"
 19 #include "jfs_filsys.h"
 20 #include "jfs_metapage.h"
 21 #include "jfs_txnmgr.h"
 22 #include "jfs_debug.h"
 23 
 24 #ifdef CONFIG_JFS_STATISTICS
 25 static struct {
 26         uint    pagealloc;      /* # of page allocations */
 27         uint    pagefree;       /* # of page frees */
 28         uint    lockwait;       /* # of sleeping lock_metapage() calls */
 29 } mpStat;
 30 #endif
 31 
 32 #define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
 33 #define trylock_metapage(mp) test_and_set_bit_lock(META_locked, &(mp)->flag)
 34 
 35 static inline void unlock_metapage(struct metapage *mp)
 36 {
 37         clear_bit_unlock(META_locked, &mp->flag);
 38         wake_up(&mp->wait);
 39 }
 40 
 41 static inline void __lock_metapage(struct metapage *mp)
 42 {
 43         DECLARE_WAITQUEUE(wait, current);
 44         INCREMENT(mpStat.lockwait);
 45         add_wait_queue_exclusive(&mp->wait, &wait);
 46         do {
 47                 set_current_state(TASK_UNINTERRUPTIBLE);
 48                 if (metapage_locked(mp)) {
 49                         unlock_page(mp->page);
 50                         io_schedule();
 51                         lock_page(mp->page);
 52                 }
 53         } while (trylock_metapage(mp));
 54         __set_current_state(TASK_RUNNING);
 55         remove_wait_queue(&mp->wait, &wait);
 56 }
 57 
 58 /*
 59  * Must have mp->page locked
 60  */
 61 static inline void lock_metapage(struct metapage *mp)
 62 {
 63         if (trylock_metapage(mp))
 64                 __lock_metapage(mp);
 65 }
 66 
 67 #define METAPOOL_MIN_PAGES 32
 68 static struct kmem_cache *metapage_cache;
 69 static mempool_t *metapage_mempool;
 70 
 71 #define MPS_PER_PAGE (PAGE_SIZE >> L2PSIZE)
 72 
 73 #if MPS_PER_PAGE > 1
 74 
 75 struct meta_anchor {
 76         int mp_count;
 77         atomic_t io_count;
 78         struct metapage *mp[MPS_PER_PAGE];
 79 };
 80 #define mp_anchor(page) ((struct meta_anchor *)page_private(page))
 81 
 82 static inline struct metapage *page_to_mp(struct page *page, int offset)
 83 {
 84         if (!PagePrivate(page))
 85                 return NULL;
 86         return mp_anchor(page)->mp[offset >> L2PSIZE];
 87 }
 88 
 89 static inline int insert_metapage(struct page *page, struct metapage *mp)
 90 {
 91         struct meta_anchor *a;
 92         int index;
 93         int l2mp_blocks;        /* log2 blocks per metapage */
 94 
 95         if (PagePrivate(page))
 96                 a = mp_anchor(page);
 97         else {
 98                 a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
 99                 if (!a)
100                         return -ENOMEM;
101                 set_page_private(page, (unsigned long)a);
102                 SetPagePrivate(page);
103                 kmap(page);
104         }
105 
106         if (mp) {
107                 l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
108                 index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
109                 a->mp_count++;
110                 a->mp[index] = mp;
111         }
112 
113         return 0;
114 }
115 
116 static inline void remove_metapage(struct page *page, struct metapage *mp)
117 {
118         struct meta_anchor *a = mp_anchor(page);
119         int l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
120         int index;
121 
122         index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
123 
124         BUG_ON(a->mp[index] != mp);
125 
126         a->mp[index] = NULL;
127         if (--a->mp_count == 0) {
128                 kfree(a);
129                 set_page_private(page, 0);
130                 ClearPagePrivate(page);
131                 kunmap(page);
132         }
133 }
134 
135 static inline void inc_io(struct page *page)
136 {
137         atomic_inc(&mp_anchor(page)->io_count);
138 }
139 
140 static inline void dec_io(struct page *page, void (*handler) (struct page *))
141 {
142         if (atomic_dec_and_test(&mp_anchor(page)->io_count))
143                 handler(page);
144 }
145 
146 #else
147 static inline struct metapage *page_to_mp(struct page *page, int offset)
148 {
149         return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
150 }
151 
152 static inline int insert_metapage(struct page *page, struct metapage *mp)
153 {
154         if (mp) {
155                 set_page_private(page, (unsigned long)mp);
156                 SetPagePrivate(page);
157                 kmap(page);
158         }
159         return 0;
160 }
161 
162 static inline void remove_metapage(struct page *page, struct metapage *mp)
163 {
164         set_page_private(page, 0);
165         ClearPagePrivate(page);
166         kunmap(page);
167 }
168 
169 #define inc_io(page) do {} while(0)
170 #define dec_io(page, handler) handler(page)
171 
172 #endif
173 
174 static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
175 {
176         struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
177 
178         if (mp) {
179                 mp->lid = 0;
180                 mp->lsn = 0;
181                 mp->data = NULL;
182                 mp->clsn = 0;
183                 mp->log = NULL;
184                 init_waitqueue_head(&mp->wait);
185         }
186         return mp;
187 }
188 
189 static inline void free_metapage(struct metapage *mp)
190 {
191         mempool_free(mp, metapage_mempool);
192 }
193 
194 int __init metapage_init(void)
195 {
196         /*
197          * Allocate the metapage structures
198          */
199         metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
200                                            0, 0, NULL);
201         if (metapage_cache == NULL)
202                 return -ENOMEM;
203 
204         metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
205                                                     metapage_cache);
206 
207         if (metapage_mempool == NULL) {
208                 kmem_cache_destroy(metapage_cache);
209                 return -ENOMEM;
210         }
211 
212         return 0;
213 }
214 
215 void metapage_exit(void)
216 {
217         mempool_destroy(metapage_mempool);
218         kmem_cache_destroy(metapage_cache);
219 }
220 
221 static inline void drop_metapage(struct page *page, struct metapage *mp)
222 {
223         if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
224             test_bit(META_io, &mp->flag))
225                 return;
226         remove_metapage(page, mp);
227         INCREMENT(mpStat.pagefree);
228         free_metapage(mp);
229 }
230 
231 /*
232  * Metapage address space operations
233  */
234 
235 static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
236                                     int *len)
237 {
238         int rc = 0;
239         int xflag;
240         s64 xaddr;
241         sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
242                                inode->i_blkbits;
243 
244         if (lblock >= file_blocks)
245                 return 0;
246         if (lblock + *len > file_blocks)
247                 *len = file_blocks - lblock;
248 
249         if (inode->i_ino) {
250                 rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
251                 if ((rc == 0) && *len)
252                         lblock = (sector_t)xaddr;
253                 else
254                         lblock = 0;
255         } /* else no mapping */
256 
257         return lblock;
258 }
259 
260 static void last_read_complete(struct page *page)
261 {
262         if (!PageError(page))
263                 SetPageUptodate(page);
264         unlock_page(page);
265 }
266 
267 static void metapage_read_end_io(struct bio *bio)
268 {
269         struct page *page = bio->bi_private;
270 
271         if (bio->bi_status) {
272                 printk(KERN_ERR "metapage_read_end_io: I/O error\n");
273                 SetPageError(page);
274         }
275 
276         dec_io(page, last_read_complete);
277         bio_put(bio);
278 }
279 
280 static void remove_from_logsync(struct metapage *mp)
281 {
282         struct jfs_log *log = mp->log;
283         unsigned long flags;
284 /*
285  * This can race.  Recheck that log hasn't been set to null, and after
286  * acquiring logsync lock, recheck lsn
287  */
288         if (!log)
289                 return;
290 
291         LOGSYNC_LOCK(log, flags);
292         if (mp->lsn) {
293                 mp->log = NULL;
294                 mp->lsn = 0;
295                 mp->clsn = 0;
296                 log->count--;
297                 list_del(&mp->synclist);
298         }
299         LOGSYNC_UNLOCK(log, flags);
300 }
301 
302 static void last_write_complete(struct page *page)
303 {
304         struct metapage *mp;
305         unsigned int offset;
306 
307         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
308                 mp = page_to_mp(page, offset);
309                 if (mp && test_bit(META_io, &mp->flag)) {
310                         if (mp->lsn)
311                                 remove_from_logsync(mp);
312                         clear_bit(META_io, &mp->flag);
313                 }
314                 /*
315                  * I'd like to call drop_metapage here, but I don't think it's
316                  * safe unless I have the page locked
317                  */
318         }
319         end_page_writeback(page);
320 }
321 
322 static void metapage_write_end_io(struct bio *bio)
323 {
324         struct page *page = bio->bi_private;
325 
326         BUG_ON(!PagePrivate(page));
327 
328         if (bio->bi_status) {
329                 printk(KERN_ERR "metapage_write_end_io: I/O error\n");
330                 SetPageError(page);
331         }
332         dec_io(page, last_write_complete);
333         bio_put(bio);
334 }
335 
336 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
337 {
338         struct bio *bio = NULL;
339         int block_offset;       /* block offset of mp within page */
340         struct inode *inode = page->mapping->host;
341         int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
342         int len;
343         int xlen;
344         struct metapage *mp;
345         int redirty = 0;
346         sector_t lblock;
347         int nr_underway = 0;
348         sector_t pblock;
349         sector_t next_block = 0;
350         sector_t page_start;
351         unsigned long bio_bytes = 0;
352         unsigned long bio_offset = 0;
353         int offset;
354         int bad_blocks = 0;
355 
356         page_start = (sector_t)page->index <<
357                      (PAGE_SHIFT - inode->i_blkbits);
358         BUG_ON(!PageLocked(page));
359         BUG_ON(PageWriteback(page));
360         set_page_writeback(page);
361 
362         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
363                 mp = page_to_mp(page, offset);
364 
365                 if (!mp || !test_bit(META_dirty, &mp->flag))
366                         continue;
367 
368                 if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
369                         redirty = 1;
370                         /*
371                          * Make sure this page isn't blocked indefinitely.
372                          * If the journal isn't undergoing I/O, push it
373                          */
374                         if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
375                                 jfs_flush_journal(mp->log, 0);
376                         continue;
377                 }
378 
379                 clear_bit(META_dirty, &mp->flag);
380                 set_bit(META_io, &mp->flag);
381                 block_offset = offset >> inode->i_blkbits;
382                 lblock = page_start + block_offset;
383                 if (bio) {
384                         if (xlen && lblock == next_block) {
385                                 /* Contiguous, in memory & on disk */
386                                 len = min(xlen, blocks_per_mp);
387                                 xlen -= len;
388                                 bio_bytes += len << inode->i_blkbits;
389                                 continue;
390                         }
391                         /* Not contiguous */
392                         if (bio_add_page(bio, page, bio_bytes, bio_offset) <
393                             bio_bytes)
394                                 goto add_failed;
395                         /*
396                          * Increment counter before submitting i/o to keep
397                          * count from hitting zero before we're through
398                          */
399                         inc_io(page);
400                         if (!bio->bi_iter.bi_size)
401                                 goto dump_bio;
402                         submit_bio(bio);
403                         nr_underway++;
404                         bio = NULL;
405                 } else
406                         inc_io(page);
407                 xlen = (PAGE_SIZE - offset) >> inode->i_blkbits;
408                 pblock = metapage_get_blocks(inode, lblock, &xlen);
409                 if (!pblock) {
410                         printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
411                         /*
412                          * We already called inc_io(), but can't cancel it
413                          * with dec_io() until we're done with the page
414                          */
415                         bad_blocks++;
416                         continue;
417                 }
418                 len = min(xlen, (int)JFS_SBI(inode->i_sb)->nbperpage);
419 
420                 bio = bio_alloc(inode->i_sb->s_bdev, 1, REQ_OP_WRITE, GFP_NOFS);
421                 bio->bi_iter.bi_sector = pblock << (inode->i_blkbits - 9);
422                 bio->bi_end_io = metapage_write_end_io;
423                 bio->bi_private = page;
424 
425                 /* Don't call bio_add_page yet, we may add to this vec */
426                 bio_offset = offset;
427                 bio_bytes = len << inode->i_blkbits;
428 
429                 xlen -= len;
430                 next_block = lblock + len;
431         }
432         if (bio) {
433                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
434                                 goto add_failed;
435                 if (!bio->bi_iter.bi_size)
436                         goto dump_bio;
437 
438                 submit_bio(bio);
439                 nr_underway++;
440         }
441         if (redirty)
442                 redirty_page_for_writepage(wbc, page);
443 
444         unlock_page(page);
445 
446         if (bad_blocks)
447                 goto err_out;
448 
449         if (nr_underway == 0)
450                 end_page_writeback(page);
451 
452         return 0;
453 add_failed:
454         /* We should never reach here, since we're only adding one vec */
455         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
456         goto skip;
457 dump_bio:
458         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
459                        4, bio, sizeof(*bio), 0);
460 skip:
461         bio_put(bio);
462         unlock_page(page);
463         dec_io(page, last_write_complete);
464 err_out:
465         while (bad_blocks--)
466                 dec_io(page, last_write_complete);
467         return -EIO;
468 }
469 
470 static int metapage_read_folio(struct file *fp, struct folio *folio)
471 {
472         struct page *page = &folio->page;
473         struct inode *inode = page->mapping->host;
474         struct bio *bio = NULL;
475         int block_offset;
476         int blocks_per_page = i_blocks_per_page(inode, page);
477         sector_t page_start;    /* address of page in fs blocks */
478         sector_t pblock;
479         int xlen;
480         unsigned int len;
481         int offset;
482 
483         BUG_ON(!PageLocked(page));
484         page_start = (sector_t)page->index <<
485                      (PAGE_SHIFT - inode->i_blkbits);
486 
487         block_offset = 0;
488         while (block_offset < blocks_per_page) {
489                 xlen = blocks_per_page - block_offset;
490                 pblock = metapage_get_blocks(inode, page_start + block_offset,
491                                              &xlen);
492                 if (pblock) {
493                         if (!PagePrivate(page))
494                                 insert_metapage(page, NULL);
495                         inc_io(page);
496                         if (bio)
497                                 submit_bio(bio);
498 
499                         bio = bio_alloc(inode->i_sb->s_bdev, 1, REQ_OP_READ,
500                                         GFP_NOFS);
501                         bio->bi_iter.bi_sector =
502                                 pblock << (inode->i_blkbits - 9);
503                         bio->bi_end_io = metapage_read_end_io;
504                         bio->bi_private = page;
505                         len = xlen << inode->i_blkbits;
506                         offset = block_offset << inode->i_blkbits;
507                         if (bio_add_page(bio, page, len, offset) < len)
508                                 goto add_failed;
509                         block_offset += xlen;
510                 } else
511                         block_offset++;
512         }
513         if (bio)
514                 submit_bio(bio);
515         else
516                 unlock_page(page);
517 
518         return 0;
519 
520 add_failed:
521         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
522         bio_put(bio);
523         dec_io(page, last_read_complete);
524         return -EIO;
525 }
526 
527 static bool metapage_release_folio(struct folio *folio, gfp_t gfp_mask)
528 {
529         struct metapage *mp;
530         bool ret = true;
531         int offset;
532 
533         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
534                 mp = page_to_mp(&folio->page, offset);
535 
536                 if (!mp)
537                         continue;
538 
539                 jfs_info("metapage_release_folio: mp = 0x%p", mp);
540                 if (mp->count || mp->nohomeok ||
541                     test_bit(META_dirty, &mp->flag)) {
542                         jfs_info("count = %ld, nohomeok = %d", mp->count,
543                                  mp->nohomeok);
544                         ret = false;
545                         continue;
546                 }
547                 if (mp->lsn)
548                         remove_from_logsync(mp);
549                 remove_metapage(&folio->page, mp);
550                 INCREMENT(mpStat.pagefree);
551                 free_metapage(mp);
552         }
553         return ret;
554 }
555 
556 static void metapage_invalidate_folio(struct folio *folio, size_t offset,
557                                     size_t length)
558 {
559         BUG_ON(offset || length < folio_size(folio));
560 
561         BUG_ON(folio_test_writeback(folio));
562 
563         metapage_release_folio(folio, 0);
564 }
565 
566 const struct address_space_operations jfs_metapage_aops = {
567         .read_folio     = metapage_read_folio,
568         .writepage      = metapage_writepage,
569         .release_folio  = metapage_release_folio,
570         .invalidate_folio = metapage_invalidate_folio,
571         .dirty_folio    = filemap_dirty_folio,
572 };
573 
574 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
575                                 unsigned int size, int absolute,
576                                 unsigned long new)
577 {
578         int l2BlocksPerPage;
579         int l2bsize;
580         struct address_space *mapping;
581         struct metapage *mp = NULL;
582         struct page *page;
583         unsigned long page_index;
584         unsigned long page_offset;
585 
586         jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
587                  inode->i_ino, lblock, absolute);
588 
589         l2bsize = inode->i_blkbits;
590         l2BlocksPerPage = PAGE_SHIFT - l2bsize;
591         page_index = lblock >> l2BlocksPerPage;
592         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
593         if ((page_offset + size) > PAGE_SIZE) {
594                 jfs_err("MetaData crosses page boundary!!");
595                 jfs_err("lblock = %lx, size  = %d", lblock, size);
596                 dump_stack();
597                 return NULL;
598         }
599         if (absolute)
600                 mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
601         else {
602                 /*
603                  * If an nfs client tries to read an inode that is larger
604                  * than any existing inodes, we may try to read past the
605                  * end of the inode map
606                  */
607                 if ((lblock << inode->i_blkbits) >= inode->i_size)
608                         return NULL;
609                 mapping = inode->i_mapping;
610         }
611 
612         if (new && (PSIZE == PAGE_SIZE)) {
613                 page = grab_cache_page(mapping, page_index);
614                 if (!page) {
615                         jfs_err("grab_cache_page failed!");
616                         return NULL;
617                 }
618                 SetPageUptodate(page);
619         } else {
620                 page = read_mapping_page(mapping, page_index, NULL);
621                 if (IS_ERR(page) || !PageUptodate(page)) {
622                         jfs_err("read_mapping_page failed!");
623                         return NULL;
624                 }
625                 lock_page(page);
626         }
627 
628         mp = page_to_mp(page, page_offset);
629         if (mp) {
630                 if (mp->logical_size != size) {
631                         jfs_error(inode->i_sb,
632                                   "get_mp->logical_size != size\n");
633                         jfs_err("logical_size = %d, size = %d",
634                                 mp->logical_size, size);
635                         dump_stack();
636                         goto unlock;
637                 }
638                 mp->count++;
639                 lock_metapage(mp);
640                 if (test_bit(META_discard, &mp->flag)) {
641                         if (!new) {
642                                 jfs_error(inode->i_sb,
643                                           "using a discarded metapage\n");
644                                 discard_metapage(mp);
645                                 goto unlock;
646                         }
647                         clear_bit(META_discard, &mp->flag);
648                 }
649         } else {
650                 INCREMENT(mpStat.pagealloc);
651                 mp = alloc_metapage(GFP_NOFS);
652                 if (!mp)
653                         goto unlock;
654                 mp->page = page;
655                 mp->sb = inode->i_sb;
656                 mp->flag = 0;
657                 mp->xflag = COMMIT_PAGE;
658                 mp->count = 1;
659                 mp->nohomeok = 0;
660                 mp->logical_size = size;
661                 mp->data = page_address(page) + page_offset;
662                 mp->index = lblock;
663                 if (unlikely(insert_metapage(page, mp))) {
664                         free_metapage(mp);
665                         goto unlock;
666                 }
667                 lock_metapage(mp);
668         }
669 
670         if (new) {
671                 jfs_info("zeroing mp = 0x%p", mp);
672                 memset(mp->data, 0, PSIZE);
673         }
674 
675         unlock_page(page);
676         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
677         return mp;
678 
679 unlock:
680         unlock_page(page);
681         return NULL;
682 }
683 
684 void grab_metapage(struct metapage * mp)
685 {
686         jfs_info("grab_metapage: mp = 0x%p", mp);
687         get_page(mp->page);
688         lock_page(mp->page);
689         mp->count++;
690         lock_metapage(mp);
691         unlock_page(mp->page);
692 }
693 
694 void force_metapage(struct metapage *mp)
695 {
696         struct page *page = mp->page;
697         jfs_info("force_metapage: mp = 0x%p", mp);
698         set_bit(META_forcewrite, &mp->flag);
699         clear_bit(META_sync, &mp->flag);
700         get_page(page);
701         lock_page(page);
702         set_page_dirty(page);
703         if (write_one_page(page))
704                 jfs_error(mp->sb, "write_one_page() failed\n");
705         clear_bit(META_forcewrite, &mp->flag);
706         put_page(page);
707 }
708 
709 void hold_metapage(struct metapage *mp)
710 {
711         lock_page(mp->page);
712 }
713 
714 void put_metapage(struct metapage *mp)
715 {
716         if (mp->count || mp->nohomeok) {
717                 /* Someone else will release this */
718                 unlock_page(mp->page);
719                 return;
720         }
721         get_page(mp->page);
722         mp->count++;
723         lock_metapage(mp);
724         unlock_page(mp->page);
725         release_metapage(mp);
726 }
727 
728 void release_metapage(struct metapage * mp)
729 {
730         struct page *page = mp->page;
731         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
732 
733         BUG_ON(!page);
734 
735         lock_page(page);
736         unlock_metapage(mp);
737 
738         assert(mp->count);
739         if (--mp->count || mp->nohomeok) {
740                 unlock_page(page);
741                 put_page(page);
742                 return;
743         }
744 
745         if (test_bit(META_dirty, &mp->flag)) {
746                 set_page_dirty(page);
747                 if (test_bit(META_sync, &mp->flag)) {
748                         clear_bit(META_sync, &mp->flag);
749                         if (write_one_page(page))
750                                 jfs_error(mp->sb, "write_one_page() failed\n");
751                         lock_page(page); /* write_one_page unlocks the page */
752                 }
753         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
754                 remove_from_logsync(mp);
755 
756         /* Try to keep metapages from using up too much memory */
757         drop_metapage(page, mp);
758 
759         unlock_page(page);
760         put_page(page);
761 }
762 
763 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
764 {
765         sector_t lblock;
766         int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
767         int BlocksPerPage = 1 << l2BlocksPerPage;
768         /* All callers are interested in block device's mapping */
769         struct address_space *mapping =
770                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
771         struct metapage *mp;
772         struct page *page;
773         unsigned int offset;
774 
775         /*
776          * Mark metapages to discard.  They will eventually be
777          * released, but should not be written.
778          */
779         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
780              lblock += BlocksPerPage) {
781                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
782                 if (!page)
783                         continue;
784                 for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
785                         mp = page_to_mp(page, offset);
786                         if (!mp)
787                                 continue;
788                         if (mp->index < addr)
789                                 continue;
790                         if (mp->index >= addr + len)
791                                 break;
792 
793                         clear_bit(META_dirty, &mp->flag);
794                         set_bit(META_discard, &mp->flag);
795                         if (mp->lsn)
796                                 remove_from_logsync(mp);
797                 }
798                 unlock_page(page);
799                 put_page(page);
800         }
801 }
802 
803 #ifdef CONFIG_JFS_STATISTICS
804 int jfs_mpstat_proc_show(struct seq_file *m, void *v)
805 {
806         seq_printf(m,
807                        "JFS Metapage statistics\n"
808                        "=======================\n"
809                        "page allocations = %d\n"
810                        "page frees = %d\n"
811                        "lock waits = %d\n",
812                        mpStat.pagealloc,
813                        mpStat.pagefree,
814                        mpStat.lockwait);
815         return 0;
816 }
817 #endif
818 

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