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 int metapage_read_end_io(struct bio *bio, unsigned int bytes_done,
 284                                 int err)
 285 {
 286         struct page *page = bio->bi_private;
 287
 288         if (bio->bi_size)
 289                 return 1;
 290
 291         if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 292                 printk(KERN_ERR "metapage_read_end_io: I/O error\n");
 293                 SetPageError(page);
 294         }
 295
 296         dec_io(page, last_read_complete);
 297         bio_put(bio);
 298
 299         return 0;
 300 }
 301
 302 static void remove_from_logsync(struct metapage *mp)
 303 {
 304         struct jfs_log *log = mp->log;
 305         unsigned long flags;
 306 /*
 307  * This can race.  Recheck that log hasn't been set to null, and after
 308  * acquiring logsync lock, recheck lsn
 309  */
 310         if (!log)
 311                 return;
 312
 313         LOGSYNC_LOCK(log, flags);
 314         if (mp->lsn) {
 315                 mp->log = NULL;
 316                 mp->lsn = 0;
 317                 mp->clsn = 0;
 318                 log->count--;
 319                 list_del(&mp->synclist);
 320         }
 321         LOGSYNC_UNLOCK(log, flags);
 322 }
 323
 324 static void last_write_complete(struct page *page)
 325 {
 326         struct metapage *mp;
 327         unsigned int offset;
 328
 329         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 330                 mp = page_to_mp(page, offset);
 331                 if (mp && test_bit(META_io, &mp->flag)) {
 332                         if (mp->lsn)
 333                                 remove_from_logsync(mp);
 334                         clear_bit(META_io, &mp->flag);
 335                 }
 336                 /*
 337                  * I'd like to call drop_metapage here, but I don't think it's
 338                  * safe unless I have the page locked
 339                  */
 340         }
 341         end_page_writeback(page);
 342 }
 343
 344 static int metapage_write_end_io(struct bio *bio, unsigned int bytes_done,
 345                                  int err)
 346 {
 347         struct page *page = bio->bi_private;
 348
 349         BUG_ON(!PagePrivate(page));
 350
 351         if (bio->bi_size)
 352                 return 1;
 353
 354         if (! test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 355                 printk(KERN_ERR "metapage_write_end_io: I/O error\n");
 356                 SetPageError(page);
 357         }
 358         dec_io(page, last_write_complete);
 359         bio_put(bio);
 360         return 0;
 361 }
 362
 363 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 364 {
 365         struct bio *bio = NULL;
 366         unsigned int block_offset;      /* block offset of mp within page */
 367         struct inode *inode = page->mapping->host;
 368         unsigned int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
 369         unsigned int len;
 370         unsigned int xlen;
 371         struct metapage *mp;
 372         int redirty = 0;
 373         sector_t lblock;
 374         sector_t pblock;
 375         sector_t next_block = 0;
 376         sector_t page_start;
 377         unsigned long bio_bytes = 0;
 378         unsigned long bio_offset = 0;
 379         unsigned int offset;
 380
 381         page_start = (sector_t)page->index <<
 382                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 383         BUG_ON(!PageLocked(page));
 384         BUG_ON(PageWriteback(page));
 385
 386         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 387                 mp = page_to_mp(page, offset);
 388
 389                 if (!mp || !test_bit(META_dirty, &mp->flag))
 390                         continue;
 391
 392                 if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
 393                         redirty = 1;
 394                         /*
 395                          * Make sure this page isn't blocked indefinitely.
 396                          * If the journal isn't undergoing I/O, push it
 397                          */
 398                         if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
 399                                 jfs_flush_journal(mp->log, 0);
 400                         continue;
 401                 }
 402
 403                 clear_bit(META_dirty, &mp->flag);
 404                 block_offset = offset >> inode->i_blkbits;
 405                 lblock = page_start + block_offset;
 406                 if (bio) {
 407                         if (xlen && lblock == next_block) {
 408                                 /* Contiguous, in memory & on disk */
 409                                 len = min(xlen, blocks_per_mp);
 410                                 xlen -= len;
 411                                 bio_bytes += len << inode->i_blkbits;
 412                                 set_bit(META_io, &mp->flag);
 413                                 continue;
 414                         }
 415                         /* Not contiguous */
 416                         if (bio_add_page(bio, page, bio_bytes, bio_offset) <
 417                             bio_bytes)
 418                                 goto add_failed;
 419                         /*
 420                          * Increment counter before submitting i/o to keep
 421                          * count from hitting zero before we're through
 422                          */
 423                         inc_io(page);
 424                         if (!bio->bi_size)
 425                                 goto dump_bio;
 426                         submit_bio(WRITE, bio);
 427                         bio = NULL;
 428                 } else {
 429                         set_page_writeback(page);
 430                         inc_io(page);
 431                 }
 432                 xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
 433                 pblock = metapage_get_blocks(inode, lblock, &xlen);
 434                 if (!pblock) {
 435                         /* Need better error handling */
 436                         printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
 437                         dec_io(page, last_write_complete);
 438                         continue;
 439                 }
 440                 set_bit(META_io, &mp->flag);
 441                 len = min(xlen, (uint) JFS_SBI(inode->i_sb)->nbperpage);
 442
 443                 bio = bio_alloc(GFP_NOFS, 1);
 444                 bio->bi_bdev = inode->i_sb->s_bdev;
 445                 bio->bi_sector = pblock << (inode->i_blkbits - 9);
 446                 bio->bi_end_io = metapage_write_end_io;
 447                 bio->bi_private = page;
 448
 449                 /* Don't call bio_add_page yet, we may add to this vec */
 450                 bio_offset = offset;
 451                 bio_bytes = len << inode->i_blkbits;
 452
 453                 xlen -= len;
 454                 next_block = lblock + len;
 455         }
 456         if (bio) {
 457                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
 458                                 goto add_failed;
 459                 if (!bio->bi_size)
 460                         goto dump_bio;
 461
 462                 submit_bio(WRITE, bio);
 463         }
 464         if (redirty)
 465                 redirty_page_for_writepage(wbc, page);
 466
 467         unlock_page(page);
 468
 469         return 0;
 470 add_failed:
 471         /* We should never reach here, since we're only adding one vec */
 472         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 473         goto skip;
 474 dump_bio:
 475         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
 476                        4, bio, sizeof(*bio), 0);
 477 skip:
 478         bio_put(bio);
 479         unlock_page(page);
 480         dec_io(page, last_write_complete);
 481
 482         return -EIO;
 483 }
 484
 485 static int metapage_readpage(struct file *fp, struct page *page)
 486 {
 487         struct inode *inode = page->mapping->host;
 488         struct bio *bio = NULL;
 489         unsigned int block_offset;
 490         unsigned int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
 491         sector_t page_start;    /* address of page in fs blocks */
 492         sector_t pblock;
 493         unsigned int xlen;
 494         unsigned int len;
 495         unsigned int offset;
 496
 497         BUG_ON(!PageLocked(page));
 498         page_start = (sector_t)page->index <<
 499                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 500
 501         block_offset = 0;
 502         while (block_offset < blocks_per_page) {
 503                 xlen = blocks_per_page - block_offset;
 504                 pblock = metapage_get_blocks(inode, page_start + block_offset,
 505                                              &xlen);
 506                 if (pblock) {
 507                         if (!PagePrivate(page))
 508                                 insert_metapage(page, NULL);
 509                         inc_io(page);
 510                         if (bio)
 511                                 submit_bio(READ, bio);
 512
 513                         bio = bio_alloc(GFP_NOFS, 1);
 514                         bio->bi_bdev = inode->i_sb->s_bdev;
 515                         bio->bi_sector = pblock << (inode->i_blkbits - 9);
 516                         bio->bi_end_io = metapage_read_end_io;
 517                         bio->bi_private = page;
 518                         len = xlen << inode->i_blkbits;
 519                         offset = block_offset << inode->i_blkbits;
 520                         if (bio_add_page(bio, page, len, offset) < len)
 521                                 goto add_failed;
 522                         block_offset += xlen;
 523                 } else
 524                         block_offset++;
 525         }
 526         if (bio)
 527                 submit_bio(READ, bio);
 528         else
 529                 unlock_page(page);
 530
 531         return 0;
 532
 533 add_failed:
 534         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 535         bio_put(bio);
 536         dec_io(page, last_read_complete);
 537         return -EIO;
 538 }
 539
 540 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
 541 {
 542         struct metapage *mp;
 543         int ret = 1;
 544         unsigned int offset;
 545
 546         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 547                 mp = page_to_mp(page, offset);
 548
 549                 if (!mp)
 550                         continue;
 551
 552                 jfs_info("metapage_releasepage: mp = 0x%p", mp);
 553                 if (mp->count || mp->nohomeok ||
 554                     test_bit(META_dirty, &mp->flag)) {
 555                         jfs_info("count = %ld, nohomeok = %d", mp->count,
 556                                  mp->nohomeok);
 557                         ret = 0;
 558                         continue;
 559                 }
 560                 if (mp->lsn)
 561                         remove_from_logsync(mp);
 562                 remove_metapage(page, mp);
 563                 INCREMENT(mpStat.pagefree);
 564                 free_metapage(mp);
 565         }
 566         return ret;
 567 }
 568
 569 static void metapage_invalidatepage(struct page *page, unsigned long offset)
 570 {
 571         BUG_ON(offset);
 572
 573         BUG_ON(PageWriteback(page));
 574
 575         metapage_releasepage(page, 0);
 576 }
 577
 578 const struct address_space_operations jfs_metapage_aops = {
 579         .readpage       = metapage_readpage,
 580         .writepage      = metapage_writepage,
 581         .sync_page      = block_sync_page,
 582         .releasepage    = metapage_releasepage,
 583         .invalidatepage = metapage_invalidatepage,
 584         .set_page_dirty = __set_page_dirty_nobuffers,
 585 };
 586
 587 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 588                                 unsigned int size, int absolute,
 589                                 unsigned long new)
 590 {
 591         int l2BlocksPerPage;
 592         int l2bsize;
 593         struct address_space *mapping;
 594         struct metapage *mp = NULL;
 595         struct page *page;
 596         unsigned long page_index;
 597         unsigned long page_offset;
 598
 599         jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
 600                  inode->i_ino, lblock, absolute);
 601
 602         l2bsize = inode->i_blkbits;
 603         l2BlocksPerPage = PAGE_CACHE_SHIFT - l2bsize;
 604         page_index = lblock >> l2BlocksPerPage;
 605         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
 606         if ((page_offset + size) > PAGE_CACHE_SIZE) {
 607                 jfs_err("MetaData crosses page boundary!!");
 608                 jfs_err("lblock = %lx, size  = %d", lblock, size);
 609                 dump_stack();
 610                 return NULL;
 611         }
 612         if (absolute)
 613                 mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
 614         else {
 615                 /*
 616                  * If an nfs client tries to read an inode that is larger
 617                  * than any existing inodes, we may try to read past the
 618                  * end of the inode map
 619                  */
 620                 if ((lblock << inode->i_blkbits) >= inode->i_size)
 621                         return NULL;
 622                 mapping = inode->i_mapping;
 623         }
 624
 625         if (new && (PSIZE == PAGE_CACHE_SIZE)) {
 626                 page = grab_cache_page(mapping, page_index);
 627                 if (!page) {
 628                         jfs_err("grab_cache_page failed!");
 629                         return NULL;
 630                 }
 631                 SetPageUptodate(page);
 632         } else {
 633                 page = read_mapping_page(mapping, page_index, NULL);
 634                 if (IS_ERR(page) || !PageUptodate(page)) {
 635                         jfs_err("read_mapping_page failed!");
 636                         return NULL;
 637                 }
 638                 lock_page(page);
 639         }
 640
 641         mp = page_to_mp(page, page_offset);
 642         if (mp) {
 643                 if (mp->logical_size != size) {
 644                         jfs_error(inode->i_sb,
 645                                   "__get_metapage: mp->logical_size != size");
 646                         jfs_err("logical_size = %d, size = %d",
 647                                 mp->logical_size, size);
 648                         dump_stack();
 649                         goto unlock;
 650                 }
 651                 mp->count++;
 652                 lock_metapage(mp);
 653                 if (test_bit(META_discard, &mp->flag)) {
 654                         if (!new) {
 655                                 jfs_error(inode->i_sb,
 656                                           "__get_metapage: using a "
 657                                           "discarded metapage");
 658                                 discard_metapage(mp);
 659                                 goto unlock;
 660                         }
 661                         clear_bit(META_discard, &mp->flag);
 662                 }
 663         } else {
 664                 INCREMENT(mpStat.pagealloc);
 665                 mp = alloc_metapage(GFP_NOFS);
 666                 mp->page = page;
 667                 mp->flag = 0;
 668                 mp->xflag = COMMIT_PAGE;
 669                 mp->count = 1;
 670                 mp->nohomeok = 0;
 671                 mp->logical_size = size;
 672                 mp->data = page_address(page) + page_offset;
 673                 mp->index = lblock;
 674                 if (unlikely(insert_metapage(page, mp))) {
 675                         free_metapage(mp);
 676                         goto unlock;
 677                 }
 678                 lock_metapage(mp);
 679         }
 680
 681         if (new) {
 682                 jfs_info("zeroing mp = 0x%p", mp);
 683                 memset(mp->data, 0, PSIZE);
 684         }
 685
 686         unlock_page(page);
 687         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
 688         return mp;
 689
 690 unlock:
 691         unlock_page(page);
 692         return NULL;
 693 }
 694
 695 void grab_metapage(struct metapage * mp)
 696 {
 697         jfs_info("grab_metapage: mp = 0x%p", mp);
 698         page_cache_get(mp->page);
 699         lock_page(mp->page);
 700         mp->count++;
 701         lock_metapage(mp);
 702         unlock_page(mp->page);
 703 }
 704
 705 void force_metapage(struct metapage *mp)
 706 {
 707         struct page *page = mp->page;
 708         jfs_info("force_metapage: mp = 0x%p", mp);
 709         set_bit(META_forcewrite, &mp->flag);
 710         clear_bit(META_sync, &mp->flag);
 711         page_cache_get(page);
 712         lock_page(page);
 713         set_page_dirty(page);
 714         write_one_page(page, 1);
 715         clear_bit(META_forcewrite, &mp->flag);
 716         page_cache_release(page);
 717 }
 718
 719 void hold_metapage(struct metapage *mp)
 720 {
 721         lock_page(mp->page);
 722 }
 723
 724 void put_metapage(struct metapage *mp)
 725 {
 726         if (mp->count || mp->nohomeok) {
 727                 /* Someone else will release this */
 728                 unlock_page(mp->page);
 729                 return;
 730         }
 731         page_cache_get(mp->page);
 732         mp->count++;
 733         lock_metapage(mp);
 734         unlock_page(mp->page);
 735         release_metapage(mp);
 736 }
 737
 738 void release_metapage(struct metapage * mp)
 739 {
 740         struct page *page = mp->page;
 741         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
 742
 743         BUG_ON(!page);
 744
 745         lock_page(page);
 746         unlock_metapage(mp);
 747
 748         assert(mp->count);
 749         if (--mp->count || mp->nohomeok) {
 750                 unlock_page(page);
 751                 page_cache_release(page);
 752                 return;
 753         }
 754
 755         if (test_bit(META_dirty, &mp->flag)) {
 756                 set_page_dirty(page);
 757                 if (test_bit(META_sync, &mp->flag)) {
 758                         clear_bit(META_sync, &mp->flag);
 759                         write_one_page(page, 1);
 760                         lock_page(page); /* write_one_page unlocks the page */
 761                 }
 762         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
 763                 remove_from_logsync(mp);
 764
 765         /* Try to keep metapages from using up too much memory */
 766         drop_metapage(page, mp);
 767
 768         unlock_page(page);
 769         page_cache_release(page);
 770 }
 771
 772 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 773 {
 774         sector_t lblock;
 775         int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
 776         int BlocksPerPage = 1 << l2BlocksPerPage;
 777         /* All callers are interested in block device's mapping */
 778         struct address_space *mapping =
 779                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
 780         struct metapage *mp;
 781         struct page *page;
 782         unsigned int offset;
 783
 784         /*
 785          * Mark metapages to discard.  They will eventually be
 786          * released, but should not be written.
 787          */
 788         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
 789              lblock += BlocksPerPage) {
 790                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 791                 if (!page)
 792                         continue;
 793                 for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 794                         mp = page_to_mp(page, offset);
 795                         if (!mp)
 796                                 continue;
 797                         if (mp->index < addr)
 798                                 continue;
 799                         if (mp->index >= addr + len)
 800                                 break;
 801
 802                         clear_bit(META_dirty, &mp->flag);
 803                         set_bit(META_discard, &mp->flag);
 804                         if (mp->lsn)
 805                                 remove_from_logsync(mp);
 806                 }
 807                 unlock_page(page);
 808                 page_cache_release(page);
 809         }
 810 }
 811
 812 #ifdef CONFIG_JFS_STATISTICS
 813 int jfs_mpstat_read(char *buffer, char **start, off_t offset, int length,
 814                     int *eof, void *data)
 815 {
 816         int len = 0;
 817         off_t begin;
 818
 819         len += sprintf(buffer,
 820                        "JFS Metapage statistics\n"
 821                        "=======================\n"
 822                        "page allocations = %d\n"
 823                        "page frees = %d\n"
 824                        "lock waits = %d\n",
 825                        mpStat.pagealloc,
 826                        mpStat.pagefree,
 827                        mpStat.lockwait);
 828
 829         begin = offset;
 830         *start = buffer + begin;
 831         len -= begin;
 832
 833         if (len > length)
 834                 len = length;
 835         else
 836                 *eof = 1;
 837
 838         if (len < 0)
 839                 len = 0;
 840
 841         return len;
 842 }
 843 #endif