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/module.h>
  23 #include <linux/bio.h>
  24 #include <linux/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/mempool.h>
  28 #include <linux/seq_file.h>
  29 #include "jfs_incore.h"
  30 #include "jfs_superblock.h"
  31 #include "jfs_filsys.h"
  32 #include "jfs_metapage.h"
  33 #include "jfs_txnmgr.h"
  34 #include "jfs_debug.h"
  35
  36 #ifdef CONFIG_JFS_STATISTICS
  37 static struct {
  38         uint    pagealloc;      /* # of page allocations */
  39         uint    pagefree;       /* # of page frees */
  40         uint    lockwait;       /* # of sleeping lock_metapage() calls */
  41 } mpStat;
  42 #endif
  43
  44 #define metapage_locked(mp) test_bit(META_locked, &(mp)->flag)
  45 #define trylock_metapage(mp) test_and_set_bit_lock(META_locked, &(mp)->flag)
  46
  47 static inline void unlock_metapage(struct metapage *mp)
  48 {
  49         clear_bit_unlock(META_locked, &mp->flag);
  50         wake_up(&mp->wait);
  51 }
  52
  53 static inline void __lock_metapage(struct metapage *mp)
  54 {
  55         DECLARE_WAITQUEUE(wait, current);
  56         INCREMENT(mpStat.lockwait);
  57         add_wait_queue_exclusive(&mp->wait, &wait);
  58         do {
  59                 set_current_state(TASK_UNINTERRUPTIBLE);
  60                 if (metapage_locked(mp)) {
  61                         unlock_page(mp->page);
  62                         io_schedule();
  63                         lock_page(mp->page);
  64                 }
  65         } while (trylock_metapage(mp));
  66         __set_current_state(TASK_RUNNING);
  67         remove_wait_queue(&mp->wait, &wait);
  68 }
  69
  70 /*
  71  * Must have mp->page locked
  72  */
  73 static inline void lock_metapage(struct metapage *mp)
  74 {
  75         if (trylock_metapage(mp))
  76                 __lock_metapage(mp);
  77 }
  78
  79 #define METAPOOL_MIN_PAGES 32
  80 static struct kmem_cache *metapage_cache;
  81 static mempool_t *metapage_mempool;
  82
  83 #define MPS_PER_PAGE (PAGE_SIZE >> L2PSIZE)
  84
  85 #if MPS_PER_PAGE > 1
  86
  87 struct meta_anchor {
  88         int mp_count;
  89         atomic_t io_count;
  90         struct metapage *mp[MPS_PER_PAGE];
  91 };
  92 #define mp_anchor(page) ((struct meta_anchor *)page_private(page))
  93
  94 static inline struct metapage *page_to_mp(struct page *page, int offset)
  95 {
  96         if (!PagePrivate(page))
  97                 return NULL;
  98         return mp_anchor(page)->mp[offset >> L2PSIZE];
  99 }
 100
 101 static inline int insert_metapage(struct page *page, struct metapage *mp)
 102 {
 103         struct meta_anchor *a;
 104         int index;
 105         int l2mp_blocks;        /* log2 blocks per metapage */
 106
 107         if (PagePrivate(page))
 108                 a = mp_anchor(page);
 109         else {
 110                 a = kzalloc(sizeof(struct meta_anchor), GFP_NOFS);
 111                 if (!a)
 112                         return -ENOMEM;
 113                 set_page_private(page, (unsigned long)a);
 114                 SetPagePrivate(page);
 115                 kmap(page);
 116         }
 117
 118         if (mp) {
 119                 l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
 120                 index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
 121                 a->mp_count++;
 122                 a->mp[index] = mp;
 123         }
 124
 125         return 0;
 126 }
 127
 128 static inline void remove_metapage(struct page *page, struct metapage *mp)
 129 {
 130         struct meta_anchor *a = mp_anchor(page);
 131         int l2mp_blocks = L2PSIZE - page->mapping->host->i_blkbits;
 132         int index;
 133
 134         index = (mp->index >> l2mp_blocks) & (MPS_PER_PAGE - 1);
 135
 136         BUG_ON(a->mp[index] != mp);
 137
 138         a->mp[index] = NULL;
 139         if (--a->mp_count == 0) {
 140                 kfree(a);
 141                 set_page_private(page, 0);
 142                 ClearPagePrivate(page);
 143                 kunmap(page);
 144         }
 145 }
 146
 147 static inline void inc_io(struct page *page)
 148 {
 149         atomic_inc(&mp_anchor(page)->io_count);
 150 }
 151
 152 static inline void dec_io(struct page *page, void (*handler) (struct page *))
 153 {
 154         if (atomic_dec_and_test(&mp_anchor(page)->io_count))
 155                 handler(page);
 156 }
 157
 158 #else
 159 static inline struct metapage *page_to_mp(struct page *page, int offset)
 160 {
 161         return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
 162 }
 163
 164 static inline int insert_metapage(struct page *page, struct metapage *mp)
 165 {
 166         if (mp) {
 167                 set_page_private(page, (unsigned long)mp);
 168                 SetPagePrivate(page);
 169                 kmap(page);
 170         }
 171         return 0;
 172 }
 173
 174 static inline void remove_metapage(struct page *page, struct metapage *mp)
 175 {
 176         set_page_private(page, 0);
 177         ClearPagePrivate(page);
 178         kunmap(page);
 179 }
 180
 181 #define inc_io(page) do {} while(0)
 182 #define dec_io(page, handler) handler(page)
 183
 184 #endif
 185
 186 static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
 187 {
 188         struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
 189
 190         if (mp) {
 191                 mp->lid = 0;
 192                 mp->lsn = 0;
 193                 mp->data = NULL;
 194                 mp->clsn = 0;
 195                 mp->log = NULL;
 196                 init_waitqueue_head(&mp->wait);
 197         }
 198         return mp;
 199 }
 200
 201 static inline void free_metapage(struct metapage *mp)
 202 {
 203         mempool_free(mp, metapage_mempool);
 204 }
 205
 206 int __init metapage_init(void)
 207 {
 208         /*
 209          * Allocate the metapage structures
 210          */
 211         metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
 212                                            0, 0, NULL);
 213         if (metapage_cache == NULL)
 214                 return -ENOMEM;
 215
 216         metapage_mempool = mempool_create_slab_pool(METAPOOL_MIN_PAGES,
 217                                                     metapage_cache);
 218
 219         if (metapage_mempool == NULL) {
 220                 kmem_cache_destroy(metapage_cache);
 221                 return -ENOMEM;
 222         }
 223
 224         return 0;
 225 }
 226
 227 void metapage_exit(void)
 228 {
 229         mempool_destroy(metapage_mempool);
 230         kmem_cache_destroy(metapage_cache);
 231 }
 232
 233 static inline void drop_metapage(struct page *page, struct metapage *mp)
 234 {
 235         if (mp->count || mp->nohomeok || test_bit(META_dirty, &mp->flag) ||
 236             test_bit(META_io, &mp->flag))
 237                 return;
 238         remove_metapage(page, mp);
 239         INCREMENT(mpStat.pagefree);
 240         free_metapage(mp);
 241 }
 242
 243 /*
 244  * Metapage address space operations
 245  */
 246
 247 static sector_t metapage_get_blocks(struct inode *inode, sector_t lblock,
 248                                     int *len)
 249 {
 250         int rc = 0;
 251         int xflag;
 252         s64 xaddr;
 253         sector_t file_blocks = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
 254                                inode->i_blkbits;
 255
 256         if (lblock >= file_blocks)
 257                 return 0;
 258         if (lblock + *len > file_blocks)
 259                 *len = file_blocks - lblock;
 260
 261         if (inode->i_ino) {
 262                 rc = xtLookup(inode, (s64)lblock, *len, &xflag, &xaddr, len, 0);
 263                 if ((rc == 0) && *len)
 264                         lblock = (sector_t)xaddr;
 265                 else
 266                         lblock = 0;
 267         } /* else no mapping */
 268
 269         return lblock;
 270 }
 271
 272 static void last_read_complete(struct page *page)
 273 {
 274         if (!PageError(page))
 275                 SetPageUptodate(page);
 276         unlock_page(page);
 277 }
 278
 279 static void metapage_read_end_io(struct bio *bio)
 280 {
 281         struct page *page = bio->bi_private;
 282
 283         if (bio->bi_error) {
 284                 printk(KERN_ERR "metapage_read_end_io: I/O error\n");
 285                 SetPageError(page);
 286         }
 287
 288         dec_io(page, last_read_complete);
 289         bio_put(bio);
 290 }
 291
 292 static void remove_from_logsync(struct metapage *mp)
 293 {
 294         struct jfs_log *log = mp->log;
 295         unsigned long flags;
 296 /*
 297  * This can race.  Recheck that log hasn't been set to null, and after
 298  * acquiring logsync lock, recheck lsn
 299  */
 300         if (!log)
 301                 return;
 302
 303         LOGSYNC_LOCK(log, flags);
 304         if (mp->lsn) {
 305                 mp->log = NULL;
 306                 mp->lsn = 0;
 307                 mp->clsn = 0;
 308                 log->count--;
 309                 list_del(&mp->synclist);
 310         }
 311         LOGSYNC_UNLOCK(log, flags);
 312 }
 313
 314 static void last_write_complete(struct page *page)
 315 {
 316         struct metapage *mp;
 317         unsigned int offset;
 318
 319         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 320                 mp = page_to_mp(page, offset);
 321                 if (mp && test_bit(META_io, &mp->flag)) {
 322                         if (mp->lsn)
 323                                 remove_from_logsync(mp);
 324                         clear_bit(META_io, &mp->flag);
 325                 }
 326                 /*
 327                  * I'd like to call drop_metapage here, but I don't think it's
 328                  * safe unless I have the page locked
 329                  */
 330         }
 331         end_page_writeback(page);
 332 }
 333
 334 static void metapage_write_end_io(struct bio *bio)
 335 {
 336         struct page *page = bio->bi_private;
 337
 338         BUG_ON(!PagePrivate(page));
 339
 340         if (bio->bi_error) {
 341                 printk(KERN_ERR "metapage_write_end_io: I/O error\n");
 342                 SetPageError(page);
 343         }
 344         dec_io(page, last_write_complete);
 345         bio_put(bio);
 346 }
 347
 348 static int metapage_writepage(struct page *page, struct writeback_control *wbc)
 349 {
 350         struct bio *bio = NULL;
 351         int block_offset;       /* block offset of mp within page */
 352         struct inode *inode = page->mapping->host;
 353         int blocks_per_mp = JFS_SBI(inode->i_sb)->nbperpage;
 354         int len;
 355         int xlen;
 356         struct metapage *mp;
 357         int redirty = 0;
 358         sector_t lblock;
 359         int nr_underway = 0;
 360         sector_t pblock;
 361         sector_t next_block = 0;
 362         sector_t page_start;
 363         unsigned long bio_bytes = 0;
 364         unsigned long bio_offset = 0;
 365         int offset;
 366         int bad_blocks = 0;
 367
 368         page_start = (sector_t)page->index <<
 369                      (PAGE_SHIFT - inode->i_blkbits);
 370         BUG_ON(!PageLocked(page));
 371         BUG_ON(PageWriteback(page));
 372         set_page_writeback(page);
 373
 374         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 375                 mp = page_to_mp(page, offset);
 376
 377                 if (!mp || !test_bit(META_dirty, &mp->flag))
 378                         continue;
 379
 380                 if (mp->nohomeok && !test_bit(META_forcewrite, &mp->flag)) {
 381                         redirty = 1;
 382                         /*
 383                          * Make sure this page isn't blocked indefinitely.
 384                          * If the journal isn't undergoing I/O, push it
 385                          */
 386                         if (mp->log && !(mp->log->cflag & logGC_PAGEOUT))
 387                                 jfs_flush_journal(mp->log, 0);
 388                         continue;
 389                 }
 390
 391                 clear_bit(META_dirty, &mp->flag);
 392                 set_bit(META_io, &mp->flag);
 393                 block_offset = offset >> inode->i_blkbits;
 394                 lblock = page_start + block_offset;
 395                 if (bio) {
 396                         if (xlen && lblock == next_block) {
 397                                 /* Contiguous, in memory & on disk */
 398                                 len = min(xlen, blocks_per_mp);
 399                                 xlen -= len;
 400                                 bio_bytes += len << inode->i_blkbits;
 401                                 continue;
 402                         }
 403                         /* Not contiguous */
 404                         if (bio_add_page(bio, page, bio_bytes, bio_offset) <
 405                             bio_bytes)
 406                                 goto add_failed;
 407                         /*
 408                          * Increment counter before submitting i/o to keep
 409                          * count from hitting zero before we're through
 410                          */
 411                         inc_io(page);
 412                         if (!bio->bi_iter.bi_size)
 413                                 goto dump_bio;
 414                         submit_bio(WRITE, bio);
 415                         nr_underway++;
 416                         bio = NULL;
 417                 } else
 418                         inc_io(page);
 419                 xlen = (PAGE_SIZE - offset) >> inode->i_blkbits;
 420                 pblock = metapage_get_blocks(inode, lblock, &xlen);
 421                 if (!pblock) {
 422                         printk(KERN_ERR "JFS: metapage_get_blocks failed\n");
 423                         /*
 424                          * We already called inc_io(), but can't cancel it
 425                          * with dec_io() until we're done with the page
 426                          */
 427                         bad_blocks++;
 428                         continue;
 429                 }
 430                 len = min(xlen, (int)JFS_SBI(inode->i_sb)->nbperpage);
 431
 432                 bio = bio_alloc(GFP_NOFS, 1);
 433                 bio->bi_bdev = inode->i_sb->s_bdev;
 434                 bio->bi_iter.bi_sector = pblock << (inode->i_blkbits - 9);
 435                 bio->bi_end_io = metapage_write_end_io;
 436                 bio->bi_private = page;
 437
 438                 /* Don't call bio_add_page yet, we may add to this vec */
 439                 bio_offset = offset;
 440                 bio_bytes = len << inode->i_blkbits;
 441
 442                 xlen -= len;
 443                 next_block = lblock + len;
 444         }
 445         if (bio) {
 446                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
 447                                 goto add_failed;
 448                 if (!bio->bi_iter.bi_size)
 449                         goto dump_bio;
 450
 451                 submit_bio(WRITE, bio);
 452                 nr_underway++;
 453         }
 454         if (redirty)
 455                 redirty_page_for_writepage(wbc, page);
 456
 457         unlock_page(page);
 458
 459         if (bad_blocks)
 460                 goto err_out;
 461
 462         if (nr_underway == 0)
 463                 end_page_writeback(page);
 464
 465         return 0;
 466 add_failed:
 467         /* We should never reach here, since we're only adding one vec */
 468         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 469         goto skip;
 470 dump_bio:
 471         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
 472                        4, bio, sizeof(*bio), 0);
 473 skip:
 474         bio_put(bio);
 475         unlock_page(page);
 476         dec_io(page, last_write_complete);
 477 err_out:
 478         while (bad_blocks--)
 479                 dec_io(page, last_write_complete);
 480         return -EIO;
 481 }
 482
 483 static int metapage_readpage(struct file *fp, struct page *page)
 484 {
 485         struct inode *inode = page->mapping->host;
 486         struct bio *bio = NULL;
 487         int block_offset;
 488         int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
 489         sector_t page_start;    /* address of page in fs blocks */
 490         sector_t pblock;
 491         int xlen;
 492         unsigned int len;
 493         int offset;
 494
 495         BUG_ON(!PageLocked(page));
 496         page_start = (sector_t)page->index <<
 497                      (PAGE_SHIFT - inode->i_blkbits);
 498
 499         block_offset = 0;
 500         while (block_offset < blocks_per_page) {
 501                 xlen = blocks_per_page - block_offset;
 502                 pblock = metapage_get_blocks(inode, page_start + block_offset,
 503                                              &xlen);
 504                 if (pblock) {
 505                         if (!PagePrivate(page))
 506                                 insert_metapage(page, NULL);
 507                         inc_io(page);
 508                         if (bio)
 509                                 submit_bio(READ, bio);
 510
 511                         bio = bio_alloc(GFP_NOFS, 1);
 512                         bio->bi_bdev = inode->i_sb->s_bdev;
 513                         bio->bi_iter.bi_sector =
 514                                 pblock << (inode->i_blkbits - 9);
 515                         bio->bi_end_io = metapage_read_end_io;
 516                         bio->bi_private = page;
 517                         len = xlen << inode->i_blkbits;
 518                         offset = block_offset << inode->i_blkbits;
 519                         if (bio_add_page(bio, page, len, offset) < len)
 520                                 goto add_failed;
 521                         block_offset += xlen;
 522                 } else
 523                         block_offset++;
 524         }
 525         if (bio)
 526                 submit_bio(READ, bio);
 527         else
 528                 unlock_page(page);
 529
 530         return 0;
 531
 532 add_failed:
 533         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 534         bio_put(bio);
 535         dec_io(page, last_read_complete);
 536         return -EIO;
 537 }
 538
 539 static int metapage_releasepage(struct page *page, gfp_t gfp_mask)
 540 {
 541         struct metapage *mp;
 542         int ret = 1;
 543         int offset;
 544
 545         for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 546                 mp = page_to_mp(page, offset);
 547
 548                 if (!mp)
 549                         continue;
 550
 551                 jfs_info("metapage_releasepage: mp = 0x%p", mp);
 552                 if (mp->count || mp->nohomeok ||
 553                     test_bit(META_dirty, &mp->flag)) {
 554                         jfs_info("count = %ld, nohomeok = %d", mp->count,
 555                                  mp->nohomeok);
 556                         ret = 0;
 557                         continue;
 558                 }
 559                 if (mp->lsn)
 560                         remove_from_logsync(mp);
 561                 remove_metapage(page, mp);
 562                 INCREMENT(mpStat.pagefree);
 563                 free_metapage(mp);
 564         }
 565         return ret;
 566 }
 567
 568 static void metapage_invalidatepage(struct page *page, unsigned int offset,
 569                                     unsigned int length)
 570 {
 571         BUG_ON(offset || length < PAGE_SIZE);
 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         .releasepage    = metapage_releasepage,
 582         .invalidatepage = metapage_invalidatepage,
 583         .set_page_dirty = __set_page_dirty_nobuffers,
 584 };
 585
 586 struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
 587                                 unsigned int size, int absolute,
 588                                 unsigned long new)
 589 {
 590         int l2BlocksPerPage;
 591         int l2bsize;
 592         struct address_space *mapping;
 593         struct metapage *mp = NULL;
 594         struct page *page;
 595         unsigned long page_index;
 596         unsigned long page_offset;
 597
 598         jfs_info("__get_metapage: ino = %ld, lblock = 0x%lx, abs=%d",
 599                  inode->i_ino, lblock, absolute);
 600
 601         l2bsize = inode->i_blkbits;
 602         l2BlocksPerPage = PAGE_SHIFT - l2bsize;
 603         page_index = lblock >> l2BlocksPerPage;
 604         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
 605         if ((page_offset + size) > PAGE_SIZE) {
 606                 jfs_err("MetaData crosses page boundary!!");
 607                 jfs_err("lblock = %lx, size  = %d", lblock, size);
 608                 dump_stack();
 609                 return NULL;
 610         }
 611         if (absolute)
 612                 mapping = JFS_SBI(inode->i_sb)->direct_inode->i_mapping;
 613         else {
 614                 /*
 615                  * If an nfs client tries to read an inode that is larger
 616                  * than any existing inodes, we may try to read past the
 617                  * end of the inode map
 618                  */
 619                 if ((lblock << inode->i_blkbits) >= inode->i_size)
 620                         return NULL;
 621                 mapping = inode->i_mapping;
 622         }
 623
 624         if (new && (PSIZE == PAGE_SIZE)) {
 625                 page = grab_cache_page(mapping, page_index);
 626                 if (!page) {
 627                         jfs_err("grab_cache_page failed!");
 628                         return NULL;
 629                 }
 630                 SetPageUptodate(page);
 631         } else {
 632                 page = read_mapping_page(mapping, page_index, NULL);
 633                 if (IS_ERR(page) || !PageUptodate(page)) {
 634                         jfs_err("read_mapping_page failed!");
 635                         return NULL;
 636                 }
 637                 lock_page(page);
 638         }
 639
 640         mp = page_to_mp(page, page_offset);
 641         if (mp) {
 642                 if (mp->logical_size != size) {
 643                         jfs_error(inode->i_sb,
 644                                   "get_mp->logical_size != size\n");
 645                         jfs_err("logical_size = %d, size = %d",
 646                                 mp->logical_size, size);
 647                         dump_stack();
 648                         goto unlock;
 649                 }
 650                 mp->count++;
 651                 lock_metapage(mp);
 652                 if (test_bit(META_discard, &mp->flag)) {
 653                         if (!new) {
 654                                 jfs_error(inode->i_sb,
 655                                           "using a discarded metapage\n");
 656                                 discard_metapage(mp);
 657                                 goto unlock;
 658                         }
 659                         clear_bit(META_discard, &mp->flag);
 660                 }
 661         } else {
 662                 INCREMENT(mpStat.pagealloc);
 663                 mp = alloc_metapage(GFP_NOFS);
 664                 mp->page = page;
 665                 mp->flag = 0;
 666                 mp->xflag = COMMIT_PAGE;
 667                 mp->count = 1;
 668                 mp->nohomeok = 0;
 669                 mp->logical_size = size;
 670                 mp->data = page_address(page) + page_offset;
 671                 mp->index = lblock;
 672                 if (unlikely(insert_metapage(page, mp))) {
 673                         free_metapage(mp);
 674                         goto unlock;
 675                 }
 676                 lock_metapage(mp);
 677         }
 678
 679         if (new) {
 680                 jfs_info("zeroing mp = 0x%p", mp);
 681                 memset(mp->data, 0, PSIZE);
 682         }
 683
 684         unlock_page(page);
 685         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
 686         return mp;
 687
 688 unlock:
 689         unlock_page(page);
 690         return NULL;
 691 }
 692
 693 void grab_metapage(struct metapage * mp)
 694 {
 695         jfs_info("grab_metapage: mp = 0x%p", mp);
 696         get_page(mp->page);
 697         lock_page(mp->page);
 698         mp->count++;
 699         lock_metapage(mp);
 700         unlock_page(mp->page);
 701 }
 702
 703 void force_metapage(struct metapage *mp)
 704 {
 705         struct page *page = mp->page;
 706         jfs_info("force_metapage: mp = 0x%p", mp);
 707         set_bit(META_forcewrite, &mp->flag);
 708         clear_bit(META_sync, &mp->flag);
 709         get_page(page);
 710         lock_page(page);
 711         set_page_dirty(page);
 712         write_one_page(page, 1);
 713         clear_bit(META_forcewrite, &mp->flag);
 714         put_page(page);
 715 }
 716
 717 void hold_metapage(struct metapage *mp)
 718 {
 719         lock_page(mp->page);
 720 }
 721
 722 void put_metapage(struct metapage *mp)
 723 {
 724         if (mp->count || mp->nohomeok) {
 725                 /* Someone else will release this */
 726                 unlock_page(mp->page);
 727                 return;
 728         }
 729         get_page(mp->page);
 730         mp->count++;
 731         lock_metapage(mp);
 732         unlock_page(mp->page);
 733         release_metapage(mp);
 734 }
 735
 736 void release_metapage(struct metapage * mp)
 737 {
 738         struct page *page = mp->page;
 739         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
 740
 741         BUG_ON(!page);
 742
 743         lock_page(page);
 744         unlock_metapage(mp);
 745
 746         assert(mp->count);
 747         if (--mp->count || mp->nohomeok) {
 748                 unlock_page(page);
 749                 put_page(page);
 750                 return;
 751         }
 752
 753         if (test_bit(META_dirty, &mp->flag)) {
 754                 set_page_dirty(page);
 755                 if (test_bit(META_sync, &mp->flag)) {
 756                         clear_bit(META_sync, &mp->flag);
 757                         write_one_page(page, 1);
 758                         lock_page(page); /* write_one_page unlocks the page */
 759                 }
 760         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
 761                 remove_from_logsync(mp);
 762
 763         /* Try to keep metapages from using up too much memory */
 764         drop_metapage(page, mp);
 765
 766         unlock_page(page);
 767         put_page(page);
 768 }
 769
 770 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 771 {
 772         sector_t lblock;
 773         int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
 774         int BlocksPerPage = 1 << l2BlocksPerPage;
 775         /* All callers are interested in block device's mapping */
 776         struct address_space *mapping =
 777                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
 778         struct metapage *mp;
 779         struct page *page;
 780         unsigned int offset;
 781
 782         /*
 783          * Mark metapages to discard.  They will eventually be
 784          * released, but should not be written.
 785          */
 786         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
 787              lblock += BlocksPerPage) {
 788                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 789                 if (!page)
 790                         continue;
 791                 for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 792                         mp = page_to_mp(page, offset);
 793                         if (!mp)
 794                                 continue;
 795                         if (mp->index < addr)
 796                                 continue;
 797                         if (mp->index >= addr + len)
 798                                 break;
 799
 800                         clear_bit(META_dirty, &mp->flag);
 801                         set_bit(META_discard, &mp->flag);
 802                         if (mp->lsn)
 803                                 remove_from_logsync(mp);
 804                 }
 805                 unlock_page(page);
 806                 put_page(page);
 807         }
 808 }
 809
 810 #ifdef CONFIG_JFS_STATISTICS
 811 static int jfs_mpstat_proc_show(struct seq_file *m, void *v)
 812 {
 813         seq_printf(m,
 814                        "JFS Metapage statistics\n"
 815                        "=======================\n"
 816                        "page allocations = %d\n"
 817                        "page frees = %d\n"
 818                        "lock waits = %d\n",
 819                        mpStat.pagealloc,
 820                        mpStat.pagefree,
 821                        mpStat.lockwait);
 822         return 0;
 823 }
 824
 825 static int jfs_mpstat_proc_open(struct inode *inode, struct file *file)
 826 {
 827         return single_open(file, jfs_mpstat_proc_show, NULL);
 828 }
 829
 830 const struct file_operations jfs_mpstat_proc_fops = {
 831         .owner          = THIS_MODULE,
 832         .open           = jfs_mpstat_proc_open,
 833         .read           = seq_read,
 834         .llseek         = seq_lseek,
 835         .release        = single_release,
 836 };
 837 #endif