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         if (flags & SLAB_CTOR_CONSTRUCTOR) {
 188                 mp->lid = 0;
 189                 mp->lsn = 0;
 190                 mp->flag = 0;
 191                 mp->data = NULL;
 192                 mp->clsn = 0;
 193                 mp->log = NULL;
 194                 set_bit(META_free, &mp->flag);
 195                 init_waitqueue_head(&mp->wait);
 196         }
 197 }
 198
 199 static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
 200 {
 201         return mempool_alloc(metapage_mempool, gfp_mask);
 202 }
 203
 204 static inline void free_metapage(struct metapage *mp)
 205 {
 206         mp->flag = 0;
 207         set_bit(META_free, &mp->flag);
 208
 209         mempool_free(mp, metapage_mempool);
 210 }
 211
 212 int __init metapage_init(void)
 213 {
 214         /*
 215          * Allocate the metapage structures
 216          */
 217         metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
 218                                            0, 0, init_once, NULL);
 219         if (metapage_cache == NULL)
 220                 return -ENOMEM;
 221
 222         metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
 223                                                     metapage_cache);
 224
 225         if (metapage_mempool == NULL) {
 226                 kmem_cache_destroy(metapage_cache);
 227                 return -ENOMEM;
 228         }
 229
 230         return 0;
 231 }
 232
 233 void metapage_exit(void)
 234 {
 235         mempool_destroy(metapage_mempool);
 236         kmem_cache_destroy(metapage_cache);
 237 }
 238
 239 static inline void drop_metapage(struct page *page, struct metapage *mp)
 240 {
 241         if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
 242             test_bit(META_io, &mp->flag))
 243                 return;
 244         remove_metapage(page, mp);
 245         INCREMENT(mpStat.pagefree);
 246         free_metapage(mp);
 247 }
 248
 249 /*
 250  * Metapage address space operations
 251  */
 252
 253 static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
 254                                     unsigned int *len)
 255 {
 256         int rc = 0;
 257         int xflag;
 258         s64 xaddr;
 259         sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
 260                                inode->i_blkbits;
 261
 262         if (lblock >= file_blocks)
 263                 return 0;
 264         if (lblock + *len > file_blocks)
 265                 *len = file_blocks - lblock;
 266
 267         if (inode->i_ino) {
 268                 rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
 269                 if ((rc == 0) && *len)
 270                         lblock = (sector_t)xaddr;
 271                 else
 272                         lblock = 0;
 273         } /* else no mapping */
 274
 275         return lblock;
 276 }
 277
 278 static void last_read_complete(struct page *page)
 279 {
 280         if (!PageError(page))
 281                 SetPageUptodate(page);
 282         unlock_page(page);
 283 }
 284
 285 static int metapage_read_end_io(struct bio *bio, unsigned int bytes_done,
 286                                 int err)
 287 {
 288         struct page *page = bio->bi_private;
 289
 290         if (bio->bi_size)
 291                 return 1;
 292
 293         if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 294                 printk(KERN_ERR "metapage_read_end_io: I/O error\n");
 295                 SetPageError(page);
 296         }
 297
 298         dec_io(page, last_read_complete);
 299         bio_put(bio);
 300
 301         return 0;
 302 }
 303
 304 static void remove_from_logsync(struct metapage *mp)
 305 {
 306         struct jfs_log *log = mp->log;
 307         unsigned long flags;
 308 /*
 309  * This can race.  Recheck that log hasn't been set to null, and after
 310  * acquiring logsync lock, recheck lsn
 311  */
 312         if (!log)
 313                 return;
 314
 315         LOGSYNC_LOCK(log, flags);
 316         if (mp->lsn) {
 317                 mp->log = NULL;
 318                 mp->lsn = 0;
 319                 mp->clsn = 0;
 320                 log->count--;
 321                 list_del(&mp->synclist);
 322         }
 323         LOGSYNC_UNLOCK(log, flags);
 324 }
 325
 326 static void last_write_complete(struct page *page)
 327 {
 328         struct metapage *mp;
 329         unsigned int offset;
 330
 331         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 332                 mp = page_to_mp(page, offset);
 333                 if (mp && test_bit(META_io, &mp->flag)) {
 334                         if (mp->lsn)
 335                                 remove_from_logsync(mp);
 336                         clear_bit(META_io, &mp->flag);
 337                 }
 338                 /*
 339                  * I'd like to call drop_metapage here, but I don't think it's
 340                  * safe unless I have the page locked
 341                  */
 342         }
 343         end_page_writeback(page);
 344 }
 345
 346 static int metapage_write_end_io(struct bio *bio, unsigned int bytes_done,
 347                                  int err)
 348 {
 349         struct page *page = bio->bi_private;
 350
 351         BUG_ON(!PagePrivate(page));
 352
 353         if (bio->bi_size)
 354                 return 1;
 355
 356         if (! test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 357                 printk(KERN_ERR "metapage_write_end_io: I/O error\n");
 358                 SetPageError(page);
 359         }
 360         dec_io(page, last_write_complete);
 361         bio_put(bio);
 362         return 0;
 363 }
 364
 365 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 366 {
 367         struct bio *bio = NULL;
 368         unsigned int block_offset;      /* block offset of mp within page */
 369         struct inode *inode = page->mapping->host;
 370         unsigned int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
 371         unsigned int len;
 372         unsigned int xlen;
 373         struct metapage *mp;
 374         int redirty = 0;
 375         sector_t lblock;
 376         sector_t pblock;
 377         sector_t next_block = 0;
 378         sector_t page_start;
 379         unsigned long bio_bytes = 0;
 380         unsigned long bio_offset = 0;
 381         unsigned int offset;
 382
 383         page_start = (sector_t)page->index <<
 384                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 385         BUG_ON(!PageLocked(page));
 386         BUG_ON(PageWriteback(page));
 387
 388         for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 389                 mp = page_to_mp(page, offset);
 390
 391                 if (!mp || !test_bit(META_dirty, &mp->flag))
 392                         continue;
 393
 394                 if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
 395                         redirty = 1;
 396                         /*
 397                          * Make sure this page isn't blocked indefinitely.
 398                          * If the journal isn't undergoing I/O, push it
 399                          */
 400                         if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
 401                                 jfs_flush_journal(mp->log, 0);
 402                         continue;
 403                 }
 404
 405                 clear_bit(META_dirty, &mp->flag);
 406                 block_offset = offset >> inode->i_blkbits;
 407                 lblock = page_start + block_offset;
 408                 if (bio) {
 409                         if (xlen && lblock == next_block) {
 410                                 /* Contiguous, in memory & on disk */
 411                                 len = min(xlen, blocks_per_mp);
 412                                 xlen -= len;
 413                                 bio_bytes += len << inode->i_blkbits;
 414                                 set_bit(META_io, &mp->flag);
 415                                 continue;
 416                         }
 417                         /* Not contiguous */
 418                         if (bio_add_page(bio, page, bio_bytes, bio_offset) <
 419                             bio_bytes)
 420                                 goto add_failed;
 421                         /*
 422                          * Increment counter before submitting i/o to keep
 423                          * count from hitting zero before we're through
 424                          */
 425                         inc_io(page);
 426                         if (!bio->bi_size)
 427                                 goto dump_bio;
 428                         submit_bio(WRITE, bio);
 429                         bio = NULL;
 430                 } else {
 431                         set_page_writeback(page);
 432                         inc_io(page);
 433                 }
 434                 xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits;
 435                 pblock = metapage_get_blocks(inode, lblock, &xlen);
 436                 if (!pblock) {
 437                         /* Need better error handling */
 438                         printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
 439                         dec_io(page, last_write_complete);
 440                         continue;
 441                 }
 442                 set_bit(META_io, &mp->flag);
 443                 len = min(xlen, (uint) JFS_SBI(inode->i_sb)->nbperpage);
 444
 445                 bio = bio_alloc(GFP_NOFS, 1);
 446                 bio->bi_bdev = inode->i_sb->s_bdev;
 447                 bio->bi_sector = pblock << (inode->i_blkbits - 9);
 448                 bio->bi_end_io = metapage_write_end_io;
 449                 bio->bi_private = page;
 450
 451                 /* Don't call bio_add_page yet, we may add to this vec */
 452                 bio_offset = offset;
 453                 bio_bytes = len << inode->i_blkbits;
 454
 455                 xlen -= len;
 456                 next_block = lblock + len;
 457         }
 458         if (bio) {
 459                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
 460                                 goto add_failed;
 461                 if (!bio->bi_size)
 462                         goto dump_bio;
 463
 464                 submit_bio(WRITE, bio);
 465         }
 466         if (redirty)
 467                 redirty_page_for_writepage(wbc, page);
 468
 469         unlock_page(page);
 470
 471         return 0;
 472 add_failed:
 473         /* We should never reach here, since we're only adding one vec */
 474         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 475         goto skip;
 476 dump_bio:
 477         dump_mem("bio", bio, sizeof(*bio));
 478 skip:
 479         bio_put(bio);
 480         unlock_page(page);
 481         dec_io(page, last_write_complete);
 482
 483         return -EIO;
 484 }
 485
 486 static int metapage_readpage(struct file *fp, struct page *page)
 487 {
 488         struct inode *inode = page->mapping->host;
 489         struct bio *bio = NULL;
 490         unsigned int block_offset;
 491         unsigned int blocks_per_page = PAGE_CACHE_SIZE >> inode->i_blkbits;
 492         sector_t page_start;    /* address of page in fs blocks */
 493         sector_t pblock;
 494         unsigned int xlen;
 495         unsigned int len;
 496         unsigned int offset;
 497
 498         BUG_ON(!PageLocked(page));
 499         page_start = (sector_t)page->index <<
 500                      (PAGE_CACHE_SHIFT - inode->i_blkbits);
 501
 502         block_offset = 0;
 503         while (block_offset < blocks_per_page) {
 504                 xlen = blocks_per_page - block_offset;
 505                 pblock = metapage_get_blocks(inode, page_start + block_offset,
 506                                              &xlen);
 507                 if (pblock) {
 508                         if (!PagePrivate(page))
 509                                 insert_metapage(page, NULL);
 510                         inc_io(page);
 511                         if (bio)
 512                                 submit_bio(READ, bio);
 513
 514                         bio = bio_alloc(GFP_NOFS, 1);
 515                         bio->bi_bdev = inode->i_sb->s_bdev;
 516                         bio->bi_sector = pblock << (inode->i_blkbits - 9);
 517                         bio->bi_end_io = metapage_read_end_io;
 518                         bio->bi_private = page;
 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(READ, 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         unsigned int offset;
 546
 547         for (offset = 0; offset < PAGE_CACHE_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 long offset)
 571 {
 572         BUG_ON(offset);
 573
 574         BUG_ON(PageWriteback(page));
 575
 576         metapage_releasepage(page, 0);
 577 }
 578
 579 const struct address_space_operations jfs_metapage_aops = {
 580         .readpage       = metapage_readpage,
 581         .writepage      = metapage_writepage,
 582         .sync_page      = block_sync_page,
 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_CACHE_SHIFT - l2bsize;
 605         page_index = lblock >> l2BlocksPerPage;
 606         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
 607         if ((page_offset + size) > PAGE_CACHE_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_CACHE_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_metapage: mp->logical_size != size");
 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                                           "__get_metapage: using a "
 658                                           "discarded metapage");
 659                                 discard_metapage(mp);
 660                                 goto unlock;
 661                         }
 662                         clear_bit(META_discard, &mp->flag);
 663                 }
 664         } else {
 665                 INCREMENT(mpStat.pagealloc);
 666                 mp = alloc_metapage(GFP_NOFS);
 667                 mp->page = page;
 668                 mp->flag = 0;
 669                 mp->xflag = COMMIT_PAGE;
 670                 mp->count = 1;
 671                 mp->nohomeok = 0;
 672                 mp->logical_size = size;
 673                 mp->data = page_address(page) + page_offset;
 674                 mp->index = lblock;
 675                 if (unlikely(insert_metapage(page, mp))) {
 676                         free_metapage(mp);
 677                         goto unlock;
 678                 }
 679                 lock_metapage(mp);
 680         }
 681
 682         if (new) {
 683                 jfs_info("zeroing mp = 0x%p", mp);
 684                 memset(mp->data, 0, PSIZE);
 685         }
 686
 687         unlock_page(page);
 688         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
 689         return mp;
 690
 691 unlock:
 692         unlock_page(page);
 693         return NULL;
 694 }
 695
 696 void grab_metapage(struct metapage * mp)
 697 {
 698         jfs_info("grab_metapage: mp = 0x%p", mp);
 699         page_cache_get(mp->page);
 700         lock_page(mp->page);
 701         mp->count++;
 702         lock_metapage(mp);
 703         unlock_page(mp->page);
 704 }
 705
 706 void force_metapage(struct metapage *mp)
 707 {
 708         struct page *page = mp->page;
 709         jfs_info("force_metapage: mp = 0x%p", mp);
 710         set_bit(META_forcewrite, &mp->flag);
 711         clear_bit(META_sync, &mp->flag);
 712         page_cache_get(page);
 713         lock_page(page);
 714         set_page_dirty(page);
 715         write_one_page(page, 1);
 716         clear_bit(META_forcewrite, &mp->flag);
 717         page_cache_release(page);
 718 }
 719
 720 void hold_metapage(struct metapage *mp)
 721 {
 722         lock_page(mp->page);
 723 }
 724
 725 void put_metapage(struct metapage *mp)
 726 {
 727         if (mp->count || mp->nohomeok) {
 728                 /* Someone else will release this */
 729                 unlock_page(mp->page);
 730                 return;
 731         }
 732         page_cache_get(mp->page);
 733         mp->count++;
 734         lock_metapage(mp);
 735         unlock_page(mp->page);
 736         release_metapage(mp);
 737 }
 738
 739 void release_metapage(struct metapage * mp)
 740 {
 741         struct page *page = mp->page;
 742         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
 743
 744         BUG_ON(!page);
 745
 746         lock_page(page);
 747         unlock_metapage(mp);
 748
 749         assert(mp->count);
 750         if (--mp->count || mp->nohomeok) {
 751                 unlock_page(page);
 752                 page_cache_release(page);
 753                 return;
 754         }
 755
 756         if (test_bit(META_dirty, &mp->flag)) {
 757                 set_page_dirty(page);
 758                 if (test_bit(META_sync, &mp->flag)) {
 759                         clear_bit(META_sync, &mp->flag);
 760                         write_one_page(page, 1);
 761                         lock_page(page); /* write_one_page unlocks the page */
 762                 }
 763         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
 764                 remove_from_logsync(mp);
 765
 766         /* Try to keep metapages from using up too much memory */
 767         drop_metapage(page, mp);
 768
 769         unlock_page(page);
 770         page_cache_release(page);
 771 }
 772
 773 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 774 {
 775         sector_t lblock;
 776         int l2BlocksPerPage = PAGE_CACHE_SHIFT - ip->i_blkbits;
 777         int BlocksPerPage = 1 << l2BlocksPerPage;
 778         /* All callers are interested in block device's mapping */
 779         struct address_space *mapping =
 780                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
 781         struct metapage *mp;
 782         struct page *page;
 783         unsigned int offset;
 784
 785         /*
 786          * Mark metapages to discard.  They will eventually be
 787          * released, but should not be written.
 788          */
 789         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
 790              lblock += BlocksPerPage) {
 791                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 792                 if (!page)
 793                         continue;
 794                 for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) {
 795                         mp = page_to_mp(page, offset);
 796                         if (!mp)
 797                                 continue;
 798                         if (mp->index < addr)
 799                                 continue;
 800                         if (mp->index >= addr + len)
 801                                 break;
 802
 803                         clear_bit(META_dirty, &mp->flag);
 804                         set_bit(META_discard, &mp->flag);
 805                         if (mp->lsn)
 806                                 remove_from_logsync(mp);
 807                 }
 808                 unlock_page(page);
 809                 page_cache_release(page);
 810         }
 811 }
 812
 813 #ifdef CONFIG_JFS_STATISTICS
 814 int jfs_mpstat_read(char *buffer, char **start, off_t offset, int length,
 815                     int *eof, void *data)
 816 {
 817         int len = 0;
 818         off_t begin;
 819
 820         len += sprintf(buffer,
 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
 830         begin = offset;
 831         *start = buffer + begin;
 832         len -= begin;
 833
 834         if (len > length)
 835                 len = length;
 836         else
 837                 *eof = 1;
 838
 839         if (len < 0)
 840                 len = 0;
 841
 842         return len;
 843 }
 844 #endif