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(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                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 438
 439                 /* Don't call bio_add_page yet, we may add to this vec */
 440                 bio_offset = offset;
 441                 bio_bytes = len << inode->i_blkbits;
 442
 443                 xlen -= len;
 444                 next_block = lblock + len;
 445         }
 446         if (bio) {
 447                 if (bio_add_page(bio, page, bio_bytes, bio_offset) < bio_bytes)
 448                                 goto add_failed;
 449                 if (!bio->bi_iter.bi_size)
 450                         goto dump_bio;
 451
 452                 submit_bio(bio);
 453                 nr_underway++;
 454         }
 455         if (redirty)
 456                 redirty_page_for_writepage(wbc, page);
 457
 458         unlock_page(page);
 459
 460         if (bad_blocks)
 461                 goto err_out;
 462
 463         if (nr_underway == 0)
 464                 end_page_writeback(page);
 465
 466         return 0;
 467 add_failed:
 468         /* We should never reach here, since we're only adding one vec */
 469         printk(KERN_ERR "JFS: bio_add_page failed unexpectedly\n");
 470         goto skip;
 471 dump_bio:
 472         print_hex_dump(KERN_ERR, "JFS: dump of bio: ", DUMP_PREFIX_ADDRESS, 16,
 473                        4, bio, sizeof(*bio), 0);
 474 skip:
 475         bio_put(bio);
 476         unlock_page(page);
 477         dec_io(page, last_write_complete);
 478 err_out:
 479         while (bad_blocks--)
 480                 dec_io(page, last_write_complete);
 481         return -EIO;
 482 }
 483
 484 static int metapage_readpage(struct file *fp, struct page *page)
 485 {
 486         struct inode *inode = page->mapping->host;
 487         struct bio *bio = NULL;
 488         int block_offset;
 489         int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
 490         sector_t page_start;    /* address of page in fs blocks */
 491         sector_t pblock;
 492         int xlen;
 493         unsigned int len;
 494         int offset;
 495
 496         BUG_ON(!PageLocked(page));
 497         page_start = (sector_t)page->index <<
 498                      (PAGE_SHIFT - inode->i_blkbits);
 499
 500         block_offset = 0;
 501         while (block_offset < blocks_per_page) {
 502                 xlen = blocks_per_page - block_offset;
 503                 pblock = metapage_get_blocks(inode, page_start + block_offset,
 504                                              &xlen);
 505                 if (pblock) {
 506                         if (!PagePrivate(page))
 507                                 insert_metapage(page, NULL);
 508                         inc_io(page);
 509                         if (bio)
 510                                 submit_bio(bio);
 511
 512                         bio = bio_alloc(GFP_NOFS, 1);
 513                         bio->bi_bdev = inode->i_sb->s_bdev;
 514                         bio->bi_iter.bi_sector =
 515                                 pblock << (inode->i_blkbits - 9);
 516                         bio->bi_end_io = metapage_read_end_io;
 517                         bio->bi_private = page;
 518                         bio_set_op_attrs(bio, REQ_OP_READ, 0);
 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(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         int offset;
 546
 547         for (offset = 0; offset < PAGE_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 int offset,
 571                                     unsigned int length)
 572 {
 573         BUG_ON(offset || length < PAGE_SIZE);
 574
 575         BUG_ON(PageWriteback(page));
 576
 577         metapage_releasepage(page, 0);
 578 }
 579
 580 const struct address_space_operations jfs_metapage_aops = {
 581         .readpage       = metapage_readpage,
 582         .writepage      = metapage_writepage,
 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_SHIFT - l2bsize;
 605         page_index = lblock >> l2BlocksPerPage;
 606         page_offset = (lblock - (page_index << l2BlocksPerPage)) << l2bsize;
 607         if ((page_offset + size) > PAGE_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_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_mp->logical_size != size\n");
 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                                           "using a discarded metapage\n");
 658                                 discard_metapage(mp);
 659                                 goto unlock;
 660                         }
 661                         clear_bit(META_discard, &mp->flag);
 662                 }
 663         } else {
 664                 INCREMENT(mpStat.pagealloc);
 665                 mp = alloc_metapage(GFP_NOFS);
 666                 mp->page = page;
 667                 mp->flag = 0;
 668                 mp->xflag = COMMIT_PAGE;
 669                 mp->count = 1;
 670                 mp->nohomeok = 0;
 671                 mp->logical_size = size;
 672                 mp->data = page_address(page) + page_offset;
 673                 mp->index = lblock;
 674                 if (unlikely(insert_metapage(page, mp))) {
 675                         free_metapage(mp);
 676                         goto unlock;
 677                 }
 678                 lock_metapage(mp);
 679         }
 680
 681         if (new) {
 682                 jfs_info("zeroing mp = 0x%p", mp);
 683                 memset(mp->data, 0, PSIZE);
 684         }
 685
 686         unlock_page(page);
 687         jfs_info("__get_metapage: returning = 0x%p data = 0x%p", mp, mp->data);
 688         return mp;
 689
 690 unlock:
 691         unlock_page(page);
 692         return NULL;
 693 }
 694
 695 void grab_metapage(struct metapage * mp)
 696 {
 697         jfs_info("grab_metapage: mp = 0x%p", mp);
 698         get_page(mp->page);
 699         lock_page(mp->page);
 700         mp->count++;
 701         lock_metapage(mp);
 702         unlock_page(mp->page);
 703 }
 704
 705 void force_metapage(struct metapage *mp)
 706 {
 707         struct page *page = mp->page;
 708         jfs_info("force_metapage: mp = 0x%p", mp);
 709         set_bit(META_forcewrite, &mp->flag);
 710         clear_bit(META_sync, &mp->flag);
 711         get_page(page);
 712         lock_page(page);
 713         set_page_dirty(page);
 714         write_one_page(page, 1);
 715         clear_bit(META_forcewrite, &mp->flag);
 716         put_page(page);
 717 }
 718
 719 void hold_metapage(struct metapage *mp)
 720 {
 721         lock_page(mp->page);
 722 }
 723
 724 void put_metapage(struct metapage *mp)
 725 {
 726         if (mp->count || mp->nohomeok) {
 727                 /* Someone else will release this */
 728                 unlock_page(mp->page);
 729                 return;
 730         }
 731         get_page(mp->page);
 732         mp->count++;
 733         lock_metapage(mp);
 734         unlock_page(mp->page);
 735         release_metapage(mp);
 736 }
 737
 738 void release_metapage(struct metapage * mp)
 739 {
 740         struct page *page = mp->page;
 741         jfs_info("release_metapage: mp = 0x%p, flag = 0x%lx", mp, mp->flag);
 742
 743         BUG_ON(!page);
 744
 745         lock_page(page);
 746         unlock_metapage(mp);
 747
 748         assert(mp->count);
 749         if (--mp->count || mp->nohomeok) {
 750                 unlock_page(page);
 751                 put_page(page);
 752                 return;
 753         }
 754
 755         if (test_bit(META_dirty, &mp->flag)) {
 756                 set_page_dirty(page);
 757                 if (test_bit(META_sync, &mp->flag)) {
 758                         clear_bit(META_sync, &mp->flag);
 759                         write_one_page(page, 1);
 760                         lock_page(page); /* write_one_page unlocks the page */
 761                 }
 762         } else if (mp->lsn)     /* discard_metapage doesn't remove it */
 763                 remove_from_logsync(mp);
 764
 765         /* Try to keep metapages from using up too much memory */
 766         drop_metapage(page, mp);
 767
 768         unlock_page(page);
 769         put_page(page);
 770 }
 771
 772 void __invalidate_metapages(struct inode *ip, s64 addr, int len)
 773 {
 774         sector_t lblock;
 775         int l2BlocksPerPage = PAGE_SHIFT - ip->i_blkbits;
 776         int BlocksPerPage = 1 << l2BlocksPerPage;
 777         /* All callers are interested in block device's mapping */
 778         struct address_space *mapping =
 779                 JFS_SBI(ip->i_sb)->direct_inode->i_mapping;
 780         struct metapage *mp;
 781         struct page *page;
 782         unsigned int offset;
 783
 784         /*
 785          * Mark metapages to discard.  They will eventually be
 786          * released, but should not be written.
 787          */
 788         for (lblock = addr & ~(BlocksPerPage - 1); lblock < addr + len;
 789              lblock += BlocksPerPage) {
 790                 page = find_lock_page(mapping, lblock >> l2BlocksPerPage);
 791                 if (!page)
 792                         continue;
 793                 for (offset = 0; offset < PAGE_SIZE; offset += PSIZE) {
 794                         mp = page_to_mp(page, offset);
 795                         if (!mp)
 796                                 continue;
 797                         if (mp->index < addr)
 798                                 continue;
 799                         if (mp->index >= addr + len)
 800                                 break;
 801
 802                         clear_bit(META_dirty, &mp->flag);
 803                         set_bit(META_discard, &mp->flag);
 804                         if (mp->lsn)
 805                                 remove_from_logsync(mp);
 806                 }
 807                 unlock_page(page);
 808                 put_page(page);
 809         }
 810 }
 811
 812 #ifdef CONFIG_JFS_STATISTICS
 813 static int jfs_mpstat_proc_show(struct seq_file *m, void *v)
 814 {
 815         seq_printf(m,
 816                        "JFS Metapage statistics\n"
 817                        "=======================\n"
 818                        "page allocations = %d\n"
 819                        "page frees = %d\n"
 820                        "lock waits = %d\n",
 821                        mpStat.pagealloc,
 822                        mpStat.pagefree,
 823                        mpStat.lockwait);
 824         return 0;
 825 }
 826
 827 static int jfs_mpstat_proc_open(struct inode *inode, struct file *file)
 828 {
 829         return single_open(file, jfs_mpstat_proc_show, NULL);
 830 }
 831
 832 const struct file_operations jfs_mpstat_proc_fops = {
 833         .open           = jfs_mpstat_proc_open,
 834         .read           = seq_read,
 835         .llseek         = seq_lseek,
 836         .release        = single_release,
 837 };
 838 #endif