fs/jfs/jfs_metapage.c

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