fs/logfs/super.c

   1 /*
   2  * fs/logfs/super.c
   3  *
   4  * As should be obvious for Linux kernel code, license is GPLv2
   5  *
   6  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   7  *
   8  * Generally contains mount/umount code and also serves as a dump area for
   9  * any functions that don't fit elsewhere and neither justify a file of their
  10  * own.
  11  */
  12 #include "logfs.h"
  13 #include <linux/bio.h>
  14 #include <linux/slab.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/statfs.h>
  18 #include <linux/buffer_head.h>
  19
  20 static DEFINE_MUTEX(emergency_mutex);
  21 static struct page *emergency_page;
  22
  23 struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
  24 {
  25         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
  26         struct page *page;
  27         int err;
  28
  29         page = read_cache_page(mapping, index, filler, NULL);
  30         if (page)
  31                 return page;
  32
  33         /* No more pages available, switch to emergency page */
  34         printk(KERN_INFO"Logfs: Using emergency page\n");
  35         mutex_lock(&emergency_mutex);
  36         err = filler(NULL, emergency_page);
  37         if (err) {
  38                 mutex_unlock(&emergency_mutex);
  39                 printk(KERN_EMERG"Logfs: Error reading emergency page\n");
  40                 return ERR_PTR(err);
  41         }
  42         return emergency_page;
  43 }
  44
  45 void emergency_read_end(struct page *page)
  46 {
  47         if (page == emergency_page)
  48                 mutex_unlock(&emergency_mutex);
  49         else
  50                 page_cache_release(page);
  51 }
  52
  53 static void dump_segfile(struct super_block *sb)
  54 {
  55         struct logfs_super *super = logfs_super(sb);
  56         struct logfs_segment_entry se;
  57         u32 segno;
  58
  59         for (segno = 0; segno < super->s_no_segs; segno++) {
  60                 logfs_get_segment_entry(sb, segno, &se);
  61                 printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
  62                                 be32_to_cpu(se.valid));
  63                 if (++segno < super->s_no_segs) {
  64                         logfs_get_segment_entry(sb, segno, &se);
  65                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  66                                         be32_to_cpu(se.valid));
  67                 }
  68                 if (++segno < super->s_no_segs) {
  69                         logfs_get_segment_entry(sb, segno, &se);
  70                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  71                                         be32_to_cpu(se.valid));
  72                 }
  73                 if (++segno < super->s_no_segs) {
  74                         logfs_get_segment_entry(sb, segno, &se);
  75                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  76                                         be32_to_cpu(se.valid));
  77                 }
  78                 printk("\n");
  79         }
  80 }
  81
  82 /*
  83  * logfs_crash_dump - dump debug information to device
  84  *
  85  * The LogFS superblock only occupies part of a segment.  This function will
  86  * write as much debug information as it can gather into the spare space.
  87  */
  88 void logfs_crash_dump(struct super_block *sb)
  89 {
  90         dump_segfile(sb);
  91 }
  92
  93 /*
  94  * TODO: move to lib/string.c
  95  */
  96 /**
  97  * memchr_inv - Find a character in an area of memory.
  98  * @s: The memory area
  99  * @c: The byte to search for
 100  * @n: The size of the area.
 101  *
 102  * returns the address of the first character other than @c, or %NULL
 103  * if the whole buffer contains just @c.
 104  */
 105 void *memchr_inv(const void *s, int c, size_t n)
 106 {
 107         const unsigned char *p = s;
 108         while (n-- != 0)
 109                 if ((unsigned char)c != *p++)
 110                         return (void *)(p - 1);
 111
 112         return NULL;
 113 }
 114
 115 /*
 116  * FIXME: There should be a reserve for root, similar to ext2.
 117  */
 118 int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
 119 {
 120         struct super_block *sb = dentry->d_sb;
 121         struct logfs_super *super = logfs_super(sb);
 122
 123         stats->f_type           = LOGFS_MAGIC_U32;
 124         stats->f_bsize          = sb->s_blocksize;
 125         stats->f_blocks         = super->s_size >> LOGFS_BLOCK_BITS >> 3;
 126         stats->f_bfree          = super->s_free_bytes >> sb->s_blocksize_bits;
 127         stats->f_bavail         = super->s_free_bytes >> sb->s_blocksize_bits;
 128         stats->f_files          = 0;
 129         stats->f_ffree          = 0;
 130         stats->f_namelen        = LOGFS_MAX_NAMELEN;
 131         return 0;
 132 }
 133
 134 static int logfs_sb_set(struct super_block *sb, void *_super)
 135 {
 136         struct logfs_super *super = _super;
 137
 138         sb->s_fs_info = super;
 139         sb->s_mtd = super->s_mtd;
 140         sb->s_bdev = super->s_bdev;
 141         if (sb->s_bdev)
 142                 sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
 143         if (sb->s_mtd)
 144                 sb->s_bdi = sb->s_mtd->backing_dev_info;
 145         return 0;
 146 }
 147
 148 static int logfs_sb_test(struct super_block *sb, void *_super)
 149 {
 150         struct logfs_super *super = _super;
 151         struct mtd_info *mtd = super->s_mtd;
 152
 153         if (mtd && sb->s_mtd == mtd)
 154                 return 1;
 155         if (super->s_bdev && sb->s_bdev == super->s_bdev)
 156                 return 1;
 157         return 0;
 158 }
 159
 160 static void set_segment_header(struct logfs_segment_header *sh, u8 type,
 161                 u8 level, u32 segno, u32 ec)
 162 {
 163         sh->pad = 0;
 164         sh->type = type;
 165         sh->level = level;
 166         sh->segno = cpu_to_be32(segno);
 167         sh->ec = cpu_to_be32(ec);
 168         sh->gec = cpu_to_be64(segno);
 169         sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
 170 }
 171
 172 static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
 173                 u32 segno, u32 ec)
 174 {
 175         struct logfs_super *super = logfs_super(sb);
 176         struct logfs_segment_header *sh = &ds->ds_sh;
 177         int i;
 178
 179         memset(ds, 0, sizeof(*ds));
 180         set_segment_header(sh, SEG_SUPER, 0, segno, ec);
 181
 182         ds->ds_ifile_levels     = super->s_ifile_levels;
 183         ds->ds_iblock_levels    = super->s_iblock_levels;
 184         ds->ds_data_levels      = super->s_data_levels; /* XXX: Remove */
 185         ds->ds_segment_shift    = super->s_segshift;
 186         ds->ds_block_shift      = sb->s_blocksize_bits;
 187         ds->ds_write_shift      = super->s_writeshift;
 188         ds->ds_filesystem_size  = cpu_to_be64(super->s_size);
 189         ds->ds_segment_size     = cpu_to_be32(super->s_segsize);
 190         ds->ds_bad_seg_reserve  = cpu_to_be32(super->s_bad_seg_reserve);
 191         ds->ds_feature_incompat = cpu_to_be64(super->s_feature_incompat);
 192         ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
 193         ds->ds_feature_compat   = cpu_to_be64(super->s_feature_compat);
 194         ds->ds_feature_flags    = cpu_to_be64(super->s_feature_flags);
 195         ds->ds_root_reserve     = cpu_to_be64(super->s_root_reserve);
 196         ds->ds_speed_reserve    = cpu_to_be64(super->s_speed_reserve);
 197         journal_for_each(i)
 198                 ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
 199         ds->ds_magic            = cpu_to_be64(LOGFS_MAGIC);
 200         ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
 201                         LOGFS_SEGMENT_HEADERSIZE + 12);
 202 }
 203
 204 static int write_one_sb(struct super_block *sb,
 205                 struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
 206 {
 207         struct logfs_super *super = logfs_super(sb);
 208         struct logfs_disk_super *ds;
 209         struct logfs_segment_entry se;
 210         struct page *page;
 211         u64 ofs;
 212         u32 ec, segno;
 213         int err;
 214
 215         page = find_sb(sb, &ofs);
 216         if (!page)
 217                 return -EIO;
 218         ds = page_address(page);
 219         segno = seg_no(sb, ofs);
 220         logfs_get_segment_entry(sb, segno, &se);
 221         ec = be32_to_cpu(se.ec_level) >> 4;
 222         ec++;
 223         logfs_set_segment_erased(sb, segno, ec, 0);
 224         logfs_write_ds(sb, ds, segno, ec);
 225         err = super->s_devops->write_sb(sb, page);
 226         page_cache_release(page);
 227         return err;
 228 }
 229
 230 int logfs_write_sb(struct super_block *sb)
 231 {
 232         struct logfs_super *super = logfs_super(sb);
 233         int err;
 234
 235         /* First superblock */
 236         err = write_one_sb(sb, super->s_devops->find_first_sb);
 237         if (err)
 238                 return err;
 239
 240         /* Last superblock */
 241         err = write_one_sb(sb, super->s_devops->find_last_sb);
 242         if (err)
 243                 return err;
 244         return 0;
 245 }
 246
 247 static int ds_cmp(const void *ds0, const void *ds1)
 248 {
 249         size_t len = sizeof(struct logfs_disk_super);
 250
 251         /* We know the segment headers differ, so ignore them */
 252         len -= LOGFS_SEGMENT_HEADERSIZE;
 253         ds0 += LOGFS_SEGMENT_HEADERSIZE;
 254         ds1 += LOGFS_SEGMENT_HEADERSIZE;
 255         return memcmp(ds0, ds1, len);
 256 }
 257
 258 static int logfs_recover_sb(struct super_block *sb)
 259 {
 260         struct logfs_super *super = logfs_super(sb);
 261         struct logfs_disk_super _ds0, *ds0 = &_ds0;
 262         struct logfs_disk_super _ds1, *ds1 = &_ds1;
 263         int err, valid0, valid1;
 264
 265         /* read first superblock */
 266         err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
 267         if (err)
 268                 return err;
 269         /* read last superblock */
 270         err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
 271         if (err)
 272                 return err;
 273         valid0 = logfs_check_ds(ds0) == 0;
 274         valid1 = logfs_check_ds(ds1) == 0;
 275
 276         if (!valid0 && valid1) {
 277                 printk(KERN_INFO"First superblock is invalid - fixing.\n");
 278                 return write_one_sb(sb, super->s_devops->find_first_sb);
 279         }
 280         if (valid0 && !valid1) {
 281                 printk(KERN_INFO"Last superblock is invalid - fixing.\n");
 282                 return write_one_sb(sb, super->s_devops->find_last_sb);
 283         }
 284         if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
 285                 printk(KERN_INFO"Superblocks don't match - fixing.\n");
 286                 return logfs_write_sb(sb);
 287         }
 288         /* If neither is valid now, something's wrong.  Didn't we properly
 289          * check them before?!? */
 290         BUG_ON(!valid0 && !valid1);
 291         return 0;
 292 }
 293
 294 static int logfs_make_writeable(struct super_block *sb)
 295 {
 296         int err;
 297
 298         err = logfs_open_segfile(sb);
 299         if (err)
 300                 return err;
 301
 302         /* Repair any broken superblock copies */
 303         err = logfs_recover_sb(sb);
 304         if (err)
 305                 return err;
 306
 307         /* Check areas for trailing unaccounted data */
 308         err = logfs_check_areas(sb);
 309         if (err)
 310                 return err;
 311
 312         /* Do one GC pass before any data gets dirtied */
 313         logfs_gc_pass(sb);
 314
 315         /* after all initializations are done, replay the journal
 316          * for rw-mounts, if necessary */
 317         err = logfs_replay_journal(sb);
 318         if (err)
 319                 return err;
 320
 321         return 0;
 322 }
 323
 324 static int logfs_get_sb_final(struct super_block *sb, struct vfsmount *mnt)
 325 {
 326         struct logfs_super *super = logfs_super(sb);
 327         struct inode *rootdir;
 328         int err;
 329
 330         /* root dir */
 331         rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
 332         if (IS_ERR(rootdir))
 333                 goto fail;
 334
 335         sb->s_root = d_alloc_root(rootdir);
 336         if (!sb->s_root)
 337                 goto fail2;
 338
 339         super->s_erase_page = alloc_pages(GFP_KERNEL, 0);
 340         if (!super->s_erase_page)
 341                 goto fail2;
 342         memset(page_address(super->s_erase_page), 0xFF, PAGE_SIZE);
 343
 344         /* FIXME: check for read-only mounts */
 345         err = logfs_make_writeable(sb);
 346         if (err)
 347                 goto fail3;
 348
 349         log_super("LogFS: Finished mounting\n");
 350         simple_set_mnt(mnt, sb);
 351         return 0;
 352
 353 fail3:
 354         __free_page(super->s_erase_page);
 355 fail2:
 356         iput(rootdir);
 357 fail:
 358         iput(logfs_super(sb)->s_master_inode);
 359         return -EIO;
 360 }
 361
 362 int logfs_check_ds(struct logfs_disk_super *ds)
 363 {
 364         struct logfs_segment_header *sh = &ds->ds_sh;
 365
 366         if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
 367                 return -EINVAL;
 368         if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
 369                 return -EINVAL;
 370         if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
 371                                 LOGFS_SEGMENT_HEADERSIZE + 12))
 372                 return -EINVAL;
 373         return 0;
 374 }
 375
 376 static struct page *find_super_block(struct super_block *sb)
 377 {
 378         struct logfs_super *super = logfs_super(sb);
 379         struct page *first, *last;
 380
 381         first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
 382         if (!first || IS_ERR(first))
 383                 return NULL;
 384         last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
 385         if (!last || IS_ERR(first)) {
 386                 page_cache_release(first);
 387                 return NULL;
 388         }
 389
 390         if (!logfs_check_ds(page_address(first))) {
 391                 page_cache_release(last);
 392                 return first;
 393         }
 394
 395         /* First one didn't work, try the second superblock */
 396         if (!logfs_check_ds(page_address(last))) {
 397                 page_cache_release(first);
 398                 return last;
 399         }
 400
 401         /* Neither worked, sorry folks */
 402         page_cache_release(first);
 403         page_cache_release(last);
 404         return NULL;
 405 }
 406
 407 static int __logfs_read_sb(struct super_block *sb)
 408 {
 409         struct logfs_super *super = logfs_super(sb);
 410         struct page *page;
 411         struct logfs_disk_super *ds;
 412         int i;
 413
 414         page = find_super_block(sb);
 415         if (!page)
 416                 return -EIO;
 417
 418         ds = page_address(page);
 419         super->s_size = be64_to_cpu(ds->ds_filesystem_size);
 420         super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
 421         super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
 422         super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
 423         super->s_segsize = 1 << ds->ds_segment_shift;
 424         super->s_segmask = (1 << ds->ds_segment_shift) - 1;
 425         super->s_segshift = ds->ds_segment_shift;
 426         sb->s_blocksize = 1 << ds->ds_block_shift;
 427         sb->s_blocksize_bits = ds->ds_block_shift;
 428         super->s_writesize = 1 << ds->ds_write_shift;
 429         super->s_writeshift = ds->ds_write_shift;
 430         super->s_no_segs = super->s_size >> super->s_segshift;
 431         super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
 432         super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
 433         super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
 434         super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
 435         super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
 436
 437         journal_for_each(i)
 438                 super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
 439
 440         super->s_ifile_levels = ds->ds_ifile_levels;
 441         super->s_iblock_levels = ds->ds_iblock_levels;
 442         super->s_data_levels = ds->ds_data_levels;
 443         super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
 444                 + super->s_data_levels;
 445         page_cache_release(page);
 446         return 0;
 447 }
 448
 449 static int logfs_read_sb(struct super_block *sb, int read_only)
 450 {
 451         struct logfs_super *super = logfs_super(sb);
 452         int ret;
 453
 454         super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
 455         if (!super->s_btree_pool)
 456                 return -ENOMEM;
 457
 458         btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
 459         btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
 460         btree_init_mempool32(&super->s_shadow_tree.segment_map,
 461                         super->s_btree_pool);
 462
 463         ret = logfs_init_mapping(sb);
 464         if (ret)
 465                 return ret;
 466
 467         ret = __logfs_read_sb(sb);
 468         if (ret)
 469                 return ret;
 470
 471         if (super->s_feature_incompat & ~LOGFS_FEATURES_INCOMPAT)
 472                 return -EIO;
 473         if ((super->s_feature_ro_compat & ~LOGFS_FEATURES_RO_COMPAT) &&
 474                         !read_only)
 475                 return -EIO;
 476
 477         mutex_init(&super->s_dirop_mutex);
 478         mutex_init(&super->s_object_alias_mutex);
 479         INIT_LIST_HEAD(&super->s_freeing_list);
 480
 481         ret = logfs_init_rw(sb);
 482         if (ret)
 483                 return ret;
 484
 485         ret = logfs_init_areas(sb);
 486         if (ret)
 487                 return ret;
 488
 489         ret = logfs_init_gc(sb);
 490         if (ret)
 491                 return ret;
 492
 493         ret = logfs_init_journal(sb);
 494         if (ret)
 495                 return ret;
 496
 497         return 0;
 498 }
 499
 500 static void logfs_kill_sb(struct super_block *sb)
 501 {
 502         struct logfs_super *super = logfs_super(sb);
 503
 504         log_super("LogFS: Start unmounting\n");
 505         /* Alias entries slow down mount, so evict as many as possible */
 506         sync_filesystem(sb);
 507         logfs_write_anchor(sb);
 508
 509         /*
 510          * From this point on alias entries are simply dropped - and any
 511          * writes to the object store are considered bugs.
 512          */
 513         super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
 514         log_super("LogFS: Now in shutdown\n");
 515         generic_shutdown_super(sb);
 516
 517         BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
 518
 519         logfs_cleanup_gc(sb);
 520         logfs_cleanup_journal(sb);
 521         logfs_cleanup_areas(sb);
 522         logfs_cleanup_rw(sb);
 523         if (super->s_erase_page)
 524                 __free_page(super->s_erase_page);
 525         super->s_devops->put_device(sb);
 526         logfs_mempool_destroy(super->s_btree_pool);
 527         logfs_mempool_destroy(super->s_alias_pool);
 528         kfree(super);
 529         log_super("LogFS: Finished unmounting\n");
 530 }
 531
 532 int logfs_get_sb_device(struct file_system_type *type, int flags,
 533                 struct mtd_info *mtd, struct block_device *bdev,
 534                 const struct logfs_device_ops *devops, struct vfsmount *mnt)
 535 {
 536         struct logfs_super *super;
 537         struct super_block *sb;
 538         int err = -ENOMEM;
 539         static int mount_count;
 540
 541         log_super("LogFS: Start mount %x\n", mount_count++);
 542         super = kzalloc(sizeof(*super), GFP_KERNEL);
 543         if (!super)
 544                 goto err0;
 545
 546         super->s_mtd    = mtd;
 547         super->s_bdev   = bdev;
 548         err = -EINVAL;
 549         sb = sget(type, logfs_sb_test, logfs_sb_set, super);
 550         if (IS_ERR(sb))
 551                 goto err0;
 552
 553         if (sb->s_root) {
 554                 /* Device is already in use */
 555                 err = 0;
 556                 simple_set_mnt(mnt, sb);
 557                 goto err0;
 558         }
 559
 560         super->s_devops = devops;
 561
 562         /*
 563          * sb->s_maxbytes is limited to 8TB.  On 32bit systems, the page cache
 564          * only covers 16TB and the upper 8TB are used for indirect blocks.
 565          * On 64bit system we could bump up the limit, but that would make
 566          * the filesystem incompatible with 32bit systems.
 567          */
 568         sb->s_maxbytes  = (1ull << 43) - 1;
 569         sb->s_op        = &logfs_super_operations;
 570         sb->s_flags     = flags | MS_NOATIME;
 571
 572         err = logfs_read_sb(sb, sb->s_flags & MS_RDONLY);
 573         if (err)
 574                 goto err1;
 575
 576         sb->s_flags |= MS_ACTIVE;
 577         err = logfs_get_sb_final(sb, mnt);
 578         if (err)
 579                 goto err1;
 580         return 0;
 581
 582 err1:
 583         deactivate_locked_super(sb);
 584         return err;
 585 err0:
 586         kfree(super);
 587         //devops->put_device(sb);
 588         return err;
 589 }
 590
 591 static int logfs_get_sb(struct file_system_type *type, int flags,
 592                 const char *devname, void *data, struct vfsmount *mnt)
 593 {
 594         ulong mtdnr;
 595
 596         if (!devname)
 597                 return logfs_get_sb_bdev(type, flags, devname, mnt);
 598         if (strncmp(devname, "mtd", 3))
 599                 return logfs_get_sb_bdev(type, flags, devname, mnt);
 600
 601         {
 602                 char *garbage;
 603                 mtdnr = simple_strtoul(devname+3, &garbage, 0);
 604                 if (*garbage)
 605                         return -EINVAL;
 606         }
 607
 608         return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
 609 }
 610
 611 static struct file_system_type logfs_fs_type = {
 612         .owner          = THIS_MODULE,
 613         .name           = "logfs",
 614         .get_sb         = logfs_get_sb,
 615         .kill_sb        = logfs_kill_sb,
 616         .fs_flags       = FS_REQUIRES_DEV,
 617
 618 };
 619
 620 static int __init logfs_init(void)
 621 {
 622         int ret;
 623
 624         emergency_page = alloc_pages(GFP_KERNEL, 0);
 625         if (!emergency_page)
 626                 return -ENOMEM;
 627
 628         ret = logfs_compr_init();
 629         if (ret)
 630                 goto out1;
 631
 632         ret = logfs_init_inode_cache();
 633         if (ret)
 634                 goto out2;
 635
 636         return register_filesystem(&logfs_fs_type);
 637 out2:
 638         logfs_compr_exit();
 639 out1:
 640         __free_pages(emergency_page, 0);
 641         return ret;
 642 }
 643
 644 static void __exit logfs_exit(void)
 645 {
 646         unregister_filesystem(&logfs_fs_type);
 647         logfs_destroy_inode_cache();
 648         logfs_compr_exit();
 649         __free_pages(emergency_page, 0);
 650 }
 651
 652 module_init(logfs_init);
 653 module_exit(logfs_exit);
 654
 655 MODULE_LICENSE("GPL v2");
 656 MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
 657 MODULE_DESCRIPTION("scalable flash filesystem");