fs/jfs/jfs_metapage.c

   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);
 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 void metapage_read_end_io(struct bio *bio, int err)
 284 {
 285         struct page *page = bio->bi_private;
 286
 287         if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 288                 printk(KERN_ERR "metapage_read_end_io: I/O error\n");
 289                 SetPageError(page);
 290         }
 291
 292         dec_io(page, last_read_complete);
 293         bio_put(bio);
 294
 295         return 0;
 296 }
 297
 298 static void remove_from_logsync(struct metapage *mp)
 299 {
 300         struct jfs_log *log = mp->log;
 301         unsigned long flags;
 302 /*
 303  * This can race.  Recheck that log hasn't been set to null, and after
 304  * acquiring logsync lock, recheck lsn
 305  */
 306         if (!log)
 307                 return;
 308
 309         LOGSYNC_LOCK(log, flags);
 310         if (mp->lsn) {
 311                 mp->log = NULL;
 312                 mp->lsn = 0;
 313                 mp->clsn = 0;
 314                 log->count--;
 315                 list_del(&mp->synclist);
 316         }
 317         LOGSYNC_UNLOCK(log, flags);
 318 }
 319
 320 static void last_write_complete(struct page *page)
 321 {
 322         struct metapage *mp;
 323         unsigned int offset;
 324
 325         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 326                 mp = page_to_mp(page, offset);
 327                 if (mp && test_bit(META_io, &mp->flag)) {
 328                         if (mp->lsn)
 329                                 remove_from_logsync(mp);
 330                         clear_bit(META_io, &mp->flag);
 331                 }
 332                 /*
 333                  * I'd like to call drop_metapage here, but I don't think it's
 334                  * safe unless I have the page locked
 335                  */
 336         }
 337         end_page_writeback(page);
 338 }
 339
 340 static void metapage_write_end_io(struct bio *bio, int err)
 341 {
 342         struct page *page = bio->bi_private;
 343
 344         BUG_ON(!PagePrivate(page));
 345
 346         if (! test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 347                 printk(KERN_ERR "metapage_write_end_io: I/O error\n");
 348                 SetPageError(page);
 349         }
 350         dec_io(page, last_write_complete);
 351         bio_put(bio);
 352         return 0;
 353 }
 354
 355 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 356 {
 357         struct bio *bio = NULL;
 358         unsigned int block_offset;      /* block offset of mp within page */
 359         struct inode *inode = page->mapping->host;
 360         unsigned int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
 361         unsigned int len;
 362         unsigned int xlen;
 363         struct metapage *mp;
 364         int redirty = 0;
 365         sector_t lblock;
 366         sector_t pblock;
 367         sector_t next_block = 0;
 368         sector_t page_start;
 369         unsigned long bio_bytes = 0;
 370         unsigned long bio_offset = 0;
 371         unsigned int offset;
 372
 373         page_start = (sector_t)page->index <<
 374                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 375         BUG_ON(!PageLocked(page));
 376         BUG_ON(PageWriteback(page));
 377
 378         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 379                 mp = page_to_mp(page, offset);
 380
 381                 if (!mp || !test_bit(META_dirty, &mp->flag))
 382                         continue;
 383
 384                 if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
 385                         redirty = 1;
 386                         /*
 387                          * Make sure this page isn't blocked indefinitely.
 388                          * If the journal isn't undergoing I/O, push it
 389                          */
 390                         if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
 391                                 jfs_flush_journal(mp->log, 0);
 392                         continue;
 393                 }
 394
 395                 clear_bit(META_dirty, &mp->flag);
 396                 block_offset = offset >> inode->i_blkbits;
 397                 lblock = page_start + block_offset;
 398                 if (bio) {
 399                         if (xlen && lblock == next_block) {
 400                                 /* Contiguous, in memory & on disk */
 401                                 len = min(xlen, blocks_per_mp);
 402                                 xlen -= len;
 403                                 bio_bytes += len << inode->i_blkbits;
 404                                 set_bit(META_io, &mp->flag);
 405                                 continue;
 406                         }
 407                         /* Not contiguous */
 408                         if (bio_add_page(bio, page, bio_bytes, bio_offset) <
 409                             bio_bytes)
 410                                 goto add_failed;
 411                         /*
 412                          * Increment counter before submitting i/o to keep
 413                          * count from hitting zero before we're through
 414                          */
 415                         inc_io(page);
 416                         if (!bio->bi_size)
 417                                 goto dump_bio;
 418                         submit_bio(WRITE, bio);
 419                         bio = NULL;
 420                 } else {
 421                         set_page_writeback(page);
 422                         inc_io(page);
 423                 }
 424                 xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
 425                 pblock = metapage_get_blocks(inode, lblock, &xlen);
 426                 if (!pblock) {
 427                         /* Need better error handling */
 428                         printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
 429                         dec_io(page, last_write_complete);
 430                         continue;
 431                 }
 432                 set_bit(META_io, &mp->flag);
 433                 len = min(xlen, (uint) JFS_SBI(inode->i_sb)->nbperpage);
 434
 435                 bio = bio_alloc(GFP_NOFS, 1);
 436                 bio->bi_bdev = inode->i_sb->s_bdev;
 437                 bio->bi_sector = pblock << (inode->i_blkbits - 9);
 438                 bio->bi_end_io = metapage_write_end_io;
 439                 bio->bi_private = page;
 440
 441                 /* Don't call bio_add_page yet, we may add to this vec */
 442                 bio_offset = offset;
 443                 bio_bytes = len << inode->i_blkbits;
 444
 445                 xlen -= len;
 446                 next_block = lblock + len;
 447         }
 448         if (bio) {
 449                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
 450                                 goto add_failed;
 451                 if (!bio->bi_size)
 452                         goto dump_bio;
 453
 454                 submit_bio(WRITE, bio);
 455         }
 456         if (redirty)
 457                 redirty_page_for_writepage(wbc, page);
 458
 459         unlock_page(page);
 460
 461         return 0;
 462 add_failed:
 463         /* We should never reach here, since we're only adding one vec */
 464         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 465         goto skip;
 466 dump_bio:
 467         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
 468                        4, bio, sizeof(*bio), 0);
 469 skip:
 470         bio_put(bio);
 471         unlock_page(page);
 472         dec_io(page, last_write_complete);
 473
 474         return -EIO;
 475 }
 476
 477 static int metapage_readpage(struct file *fp, struct page *page)
 478 {
 479         struct inode *inode = page->mapping->host;
 480         struct bio *bio = NULL;
 481         unsigned int block_offset;
 482         unsigned int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
 483         sector_t page_start;    /* address of page in fs blocks */
 484         sector_t pblock;
 485         unsigned int xlen;
 486         unsigned int len;
 487         unsigned int offset;
 488
 489         BUG_ON(!PageLocked(page));
 490         page_start = (sector_t)page->index <<
 491                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 492
 493         block_offset = 0;
 494         while (block_offset < blocks_per_page) {
 495                 xlen = blocks_per_page - block_offset;
 496                 pblock = metapage_get_blocks(inode, page_start + block_offset,
 497                                              &xlen);
 498                 if (pblock) {
 499                         if (!PagePrivate(page))
 500                                 insert_metapage(page, NULL);
 501                         inc_io(page);
 502                         if (bio)
 503                                 submit_bio(READ, bio);
 504
 505                         bio = bio_alloc(GFP_NOFS, 1);
 506                         bio->bi_bdev = inode->i_sb->s_bdev;
 507                         bio->bi_sector = pblock << (inode->i_blkbits - 9);
 508                         bio->bi_end_io = metapage_read_end_io;
 509                         bio->bi_private = page;
 510                         len = xlen << inode->i_blkbits;
 511                         offset = block_offset << inode->i_blkbits;
 512                         if (bio_add_page(bio, page, len, offset) < len)
 513                                 goto add_failed;
 514                         block_offset += xlen;
 515                 } else
 516                         block_offset++;
 517         }
 518         if (bio)
 519                 submit_bio(READ, bio);
 520         else
 521                 unlock_page(page);
 522
 523         return 0;
 524
 525 add_failed:
 526         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 527         bio_put(bio);
 528         dec_io(page, last_read_complete);
 529         return -EIO;
 530 }
 531
 532 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
 533 {
 534         struct metapage *mp;
 535         int ret = 1;
 536         unsigned int offset;
 537
 538         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 539                 mp = page_to_mp(page, offset);
 540
 541                 if (!mp)
 542                         continue;
 543
 544                 jfs_info("metapage_releasepage: mp = 0x%p", mp);
 545                 if (mp->count || mp->nohomeok ||
 546                     test_bit(META_dirty, &mp->flag)) {
 547                         jfs_info("count = %ld, nohomeok = %d", mp->count,
 548                                  mp->nohomeok);
 549                         ret = 0;
 550                         continue;
 551                 }
 552                 if (mp->lsn)
 553                         remove_from_logsync(mp);
 554                 remove_metapage(page, mp);
 555                 INCREMENT(mpStat.pagefree);
 556                 free_metapage(mp);
 557         }
 558         return ret;
 559 }
 560
 561 static void metapage_invalidatepage(struct page *page, unsigned long offset)
 562 {
 563         BUG_ON(offset);
 564
 565         BUG_ON(PageWriteback(page));
 566
 567         metapage_releasepage(page, 0);
 568 }
 569
 570 const struct address_space_operations jfs_metapage_aops = {
 571         .readpage       = metapage_readpage,
 572         .writepage      = metapage_writepage,
 573         .sync_page      = block_sync_page,
 574         .releasepage    = metapage_releasepage,
 575         .invalidatepage = metapage_invalidatepage,
 576         .set_page_dirty = __set_page_dirty_nobuffers,
 577 };
 578
 579 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 580                                 unsigned int size, int absolute,
 581                                 unsigned long new)
 582 {
 583         int l2BlocksPerPage;
 584         int l2bsize;
 585         struct address_space *mapping;
 586         struct metapage *mp = NULL;
 587         struct page *page;
 588         unsigned long page_index;
 589         unsigned long page_offset;
 590
 591         jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
 592                  inode->i_ino, lblock, absolute);
 593
 594         l2bsize = inode->i_blkbits;
 595         l2BlocksPerPage = PAGE_CACHE_SHIFT - l2bsize;
 596         page_index = lblock >> l2BlocksPerPage;
 597         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
 598         if ((page_offset + size) > PAGE_CACHE_SIZE) {
 599                 jfs_err("MetaData crosses page boundary!!");
 600                 jfs_err("lblock = %lx, size  = %d", lblock, size);
 601                 dump_stack();
 602                 return NULL;
 603         }
 604         if (absolute)
 605                 mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
 606         else {
 607                 /*
 608                  * If an nfs client tries to read an inode that is larger
 609                  * than any existing inodes, we may try to read past the
 610                  * end of the inode map
 611                  */
 612                 if ((lblock << inode->i_blkbits) >= inode->i_size)
 613                         return NULL;
 614                 mapping = inode->i_mapping;
 615         }
 616
 617         if (new && (PSIZE == PAGE_CACHE_SIZE)) {
 618                 page = grab_cache_page(mapping, page_index);
 619                 if (!page) {
 620                         jfs_err("grab_cache_page failed!");
 621                         return NULL;
 622                 }
 623                 SetPageUptodate(page);
 624         } else {
 625                 page = read_mapping_page(mapping, page_index, NULL);
 626                 if (IS_ERR(page) || !PageUptodate(page)) {
 627                         jfs_err("read_mapping_page failed!");
 628                         return NULL;
 629                 }
 630                 lock_page(page);
 631         }
 632
 633         mp = page_to_mp(page, page_offset);
 634         if (mp) {
 635                 if (mp->logical_size != size) {
 636                         jfs_error(inode->i_sb,
 637                                   "__get_metapage: mp->logical_size != size");
 638                         jfs_err("logical_size = %d, size = %d",
 639                                 mp->logical_size, size);
 640                         dump_stack();
 641                         goto unlock;
 642                 }
 643                 mp->count++;
 644                 lock_metapage(mp);
 645                 if (test_bit(META_discard, &mp->flag)) {
 646                         if (!new) {
 647                                 jfs_error(inode->i_sb,
 648                                           "__get_metapage: using a "
 649                                           "discarded metapage");
 650                                 discard_metapage(mp);
 651                                 goto unlock;
 652                         }
 653                         clear_bit(META_discard, &mp->flag);
 654                 }
 655         } else {
 656                 INCREMENT(mpStat.pagealloc);
 657                 mp = alloc_metapage(GFP_NOFS);
 658                 mp->page = page;
 659                 mp->flag = 0;
 660                 mp->xflag = COMMIT_PAGE;
 661                 mp->count = 1;
 662                 mp->nohomeok = 0;
 663                 mp->logical_size = size;
 664                 mp->data = page_address(page) + page_offset;
 665                 mp->index = lblock;
 666                 if (unlikely(insert_metapage(page, mp))) {
 667                         free_metapage(mp);
 668                         goto unlock;
 669                 }
 670                 lock_metapage(mp);
 671         }
 672
 673         if (new) {
 674                 jfs_info("zeroing mp = 0x%p", mp);
 675                 memset(mp->data, 0, PSIZE);
 676         }
 677
 678         unlock_page(page);
 679         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
 680         return mp;
 681
 682 unlock:
 683         unlock_page(page);
 684         return NULL;
 685 }
 686
 687 void grab_metapage(struct metapage * mp)
 688 {
 689         jfs_info("grab_metapage: mp = 0x%p", mp);
 690         page_cache_get(mp->page);
 691         lock_page(mp->page);
 692         mp->count++;
 693         lock_metapage(mp);
 694         unlock_page(mp->page);
 695 }
 696
 697 void force_metapage(struct metapage *mp)
 698 {
 699         struct page *page = mp->page;
 700         jfs_info("force_metapage: mp = 0x%p", mp);
 701         set_bit(META_forcewrite, &mp->flag);
 702         clear_bit(META_sync, &mp->flag);
 703         page_cache_get(page);
 704         lock_page(page);
 705         set_page_dirty(page);
 706         write_one_page(page, 1);
 707         clear_bit(META_forcewrite, &mp->flag);
 708         page_cache_release(page);
 709 }
 710
 711 void hold_metapage(struct metapage *mp)
 712 {
 713         lock_page(mp->page);
 714 }
 715
 716 void put_metapage(struct metapage *mp)
 717 {
 718         if (mp->count || mp->nohomeok) {
 719                 /* Someone else will release this */
 720                 unlock_page(mp->page);
 721                 return;
 722         }
 723         page_cache_get(mp->page);
 724         mp->count++;
 725         lock_metapage(mp);
 726         unlock_page(mp->page);
 727         release_metapage(mp);
 728 }
 729
 730 void release_metapage(struct metapage * mp)
 731 {
 732         struct page *page = mp->page;
 733         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
 734
 735         BUG_ON(!page);
 736
 737         lock_page(page);
 738         unlock_metapage(mp);
 739
 740         assert(mp->count);
 741         if (--mp->count || mp->nohomeok) {
 742                 unlock_page(page);
 743                 page_cache_release(page);
 744                 return;
 745         }
 746
 747         if (test_bit(META_dirty, &mp->flag)) {
 748                 set_page_dirty(page);
 749                 if (test_bit(META_sync, &mp->flag)) {
 750                         clear_bit(META_sync, &mp->flag);
 751                         write_one_page(page, 1);
 752                         lock_page(page); /* write_one_page unlocks the page */
 753                 }
 754         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
 755                 remove_from_logsync(mp);
 756
 757         /* Try to keep metapages from using up too much memory */
 758         drop_metapage(page, mp);
 759
 760         unlock_page(page);
 761         page_cache_release(page);
 762 }
 763
 764 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 765 {
 766         sector_t lblock;
 767         int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
 768         int BlocksPerPage = 1 << l2BlocksPerPage;
 769         /* All callers are interested in block device's mapping */
 770         struct address_space *mapping =
 771                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
 772         struct metapage *mp;
 773         struct page *page;
 774         unsigned int offset;
 775
 776         /*
 777          * Mark metapages to discard.  They will eventually be
 778          * released, but should not be written.
 779          */
 780         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
 781              lblock += BlocksPerPage) {
 782                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 783                 if (!page)
 784                         continue;
 785                 for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 786                         mp = page_to_mp(page, offset);
 787                         if (!mp)
 788                                 continue;
 789                         if (mp->index < addr)
 790                                 continue;
 791                         if (mp->index >= addr + len)
 792                                 break;
 793
 794                         clear_bit(META_dirty, &mp->flag);
 795                         set_bit(META_discard, &mp->flag);
 796                         if (mp->lsn)
 797                                 remove_from_logsync(mp);
 798                 }
 799                 unlock_page(page);
 800                 page_cache_release(page);
 801         }
 802 }
 803
 804 #ifdef CONFIG_JFS_STATISTICS
 805 int jfs_mpstat_read(char *buffer, char **start, off_t offset, int length,
 806                     int *eof, void *data)
 807 {
 808         int len = 0;
 809         off_t begin;
 810
 811         len += sprintf(buffer,
 812                        "JFS Metapage statistics\n"
 813                        "=======================\n"
 814                        "page allocations = %d\n"
 815                        "page frees = %d\n"
 816                        "lock waits = %d\n",
 817                        mpStat.pagealloc,
 818                        mpStat.pagefree,
 819                        mpStat.lockwait);
 820
 821         begin = offset;
 822         *start = buffer + begin;
 823         len -= begin;
 824
 825         if (len > length)
 826                 len = length;
 827         else
 828                 *eof = 1;
 829
 830         if (len < 0)
 831                 len = 0;
 832
 833         return len;
 834 }
 835 #endif