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/module.h>
  17 #include <linux/mtd/mtd.h>
  18 #include <linux/statfs.h>
  19 #include <linux/buffer_head.h>
  20
  21 static DEFINE_MUTEX(emergency_mutex);
  22 static struct page *emergency_page;
  23
  24 struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
  25 {
  26         filler_t *filler = (filler_t *)mapping->a_ops->readpage;
  27         struct page *page;
  28         int err;
  29
  30         page = read_cache_page(mapping, index, filler, NULL);
  31         if (page)
  32                 return page;
  33
  34         /* No more pages available, switch to emergency page */
  35         printk(KERN_INFO"Logfs: Using emergency page\n");
  36         mutex_lock(&emergency_mutex);
  37         err = filler(NULL, emergency_page);
  38         if (err) {
  39                 mutex_unlock(&emergency_mutex);
  40                 printk(KERN_EMERG"Logfs: Error reading emergency page\n");
  41                 return ERR_PTR(err);
  42         }
  43         return emergency_page;
  44 }
  45
  46 void emergency_read_end(struct page *page)
  47 {
  48         if (page == emergency_page)
  49                 mutex_unlock(&emergency_mutex);
  50         else
  51                 page_cache_release(page);
  52 }
  53
  54 static void dump_segfile(struct super_block *sb)
  55 {
  56         struct logfs_super *super = logfs_super(sb);
  57         struct logfs_segment_entry se;
  58         u32 segno;
  59
  60         for (segno = 0; segno < super->s_no_segs; segno++) {
  61                 logfs_get_segment_entry(sb, segno, &se);
  62                 printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
  63                                 be32_to_cpu(se.valid));
  64                 if (++segno < super->s_no_segs) {
  65                         logfs_get_segment_entry(sb, segno, &se);
  66                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  67                                         be32_to_cpu(se.valid));
  68                 }
  69                 if (++segno < super->s_no_segs) {
  70                         logfs_get_segment_entry(sb, segno, &se);
  71                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  72                                         be32_to_cpu(se.valid));
  73                 }
  74                 if (++segno < super->s_no_segs) {
  75                         logfs_get_segment_entry(sb, segno, &se);
  76                         printk(" %6x %8x", be32_to_cpu(se.ec_level),
  77                                         be32_to_cpu(se.valid));
  78                 }
  79                 printk("\n");
  80         }
  81 }
  82
  83 /*
  84  * logfs_crash_dump - dump debug information to device
  85  *
  86  * The LogFS superblock only occupies part of a segment.  This function will
  87  * write as much debug information as it can gather into the spare space.
  88  */
  89 void logfs_crash_dump(struct super_block *sb)
  90 {
  91         dump_segfile(sb);
  92 }
  93
  94 /*
  95  * TODO: move to lib/string.c
  96  */
  97 /**
  98  * memchr_inv - Find a character in an area of memory.
  99  * @s: The memory area
 100  * @c: The byte to search for
 101  * @n: The size of the area.
 102  *
 103  * returns the address of the first character other than @c, or %NULL
 104  * if the whole buffer contains just @c.
 105  */
 106 void *memchr_inv(const void *s, int c, size_t n)
 107 {
 108         const unsigned char *p = s;
 109         while (n-- != 0)
 110                 if ((unsigned char)c != *p++)
 111                         return (void *)(p - 1);
 112
 113         return NULL;
 114 }
 115
 116 /*
 117  * FIXME: There should be a reserve for root, similar to ext2.
 118  */
 119 int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
 120 {
 121         struct super_block *sb = dentry->d_sb;
 122         struct logfs_super *super = logfs_super(sb);
 123
 124         stats->f_type           = LOGFS_MAGIC_U32;
 125         stats->f_bsize          = sb->s_blocksize;
 126         stats->f_blocks         = super->s_size >> LOGFS_BLOCK_BITS >> 3;
 127         stats->f_bfree          = super->s_free_bytes >> sb->s_blocksize_bits;
 128         stats->f_bavail         = super->s_free_bytes >> sb->s_blocksize_bits;
 129         stats->f_files          = 0;
 130         stats->f_ffree          = 0;
 131         stats->f_namelen        = LOGFS_MAX_NAMELEN;
 132         return 0;
 133 }
 134
 135 static int logfs_sb_set(struct super_block *sb, void *_super)
 136 {
 137         struct logfs_super *super = _super;
 138
 139         sb->s_fs_info = super;
 140         sb->s_mtd = super->s_mtd;
 141         sb->s_bdev = super->s_bdev;
 142 #ifdef CONFIG_BLOCK
 143         if (sb->s_bdev)
 144                 sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
 145 #endif
 146 #ifdef CONFIG_MTD
 147         if (sb->s_mtd)
 148                 sb->s_bdi = sb->s_mtd->backing_dev_info;
 149 #endif
 150         return 0;
 151 }
 152
 153 static int logfs_sb_test(struct super_block *sb, void *_super)
 154 {
 155         struct logfs_super *super = _super;
 156         struct mtd_info *mtd = super->s_mtd;
 157
 158         if (mtd && sb->s_mtd == mtd)
 159                 return 1;
 160         if (super->s_bdev && sb->s_bdev == super->s_bdev)
 161                 return 1;
 162         return 0;
 163 }
 164
 165 static void set_segment_header(struct logfs_segment_header *sh, u8 type,
 166                 u8 level, u32 segno, u32 ec)
 167 {
 168         sh->pad = 0;
 169         sh->type = type;
 170         sh->level = level;
 171         sh->segno = cpu_to_be32(segno);
 172         sh->ec = cpu_to_be32(ec);
 173         sh->gec = cpu_to_be64(segno);
 174         sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
 175 }
 176
 177 static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
 178                 u32 segno, u32 ec)
 179 {
 180         struct logfs_super *super = logfs_super(sb);
 181         struct logfs_segment_header *sh = &ds->ds_sh;
 182         int i;
 183
 184         memset(ds, 0, sizeof(*ds));
 185         set_segment_header(sh, SEG_SUPER, 0, segno, ec);
 186
 187         ds->ds_ifile_levels     = super->s_ifile_levels;
 188         ds->ds_iblock_levels    = super->s_iblock_levels;
 189         ds->ds_data_levels      = super->s_data_levels; /* XXX: Remove */
 190         ds->ds_segment_shift    = super->s_segshift;
 191         ds->ds_block_shift      = sb->s_blocksize_bits;
 192         ds->ds_write_shift      = super->s_writeshift;
 193         ds->ds_filesystem_size  = cpu_to_be64(super->s_size);
 194         ds->ds_segment_size     = cpu_to_be32(super->s_segsize);
 195         ds->ds_bad_seg_reserve  = cpu_to_be32(super->s_bad_seg_reserve);
 196         ds->ds_feature_incompat = cpu_to_be64(super->s_feature_incompat);
 197         ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
 198         ds->ds_feature_compat   = cpu_to_be64(super->s_feature_compat);
 199         ds->ds_feature_flags    = cpu_to_be64(super->s_feature_flags);
 200         ds->ds_root_reserve     = cpu_to_be64(super->s_root_reserve);
 201         ds->ds_speed_reserve    = cpu_to_be64(super->s_speed_reserve);
 202         journal_for_each(i)
 203                 ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
 204         ds->ds_magic            = cpu_to_be64(LOGFS_MAGIC);
 205         ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
 206                         LOGFS_SEGMENT_HEADERSIZE + 12);
 207 }
 208
 209 static int write_one_sb(struct super_block *sb,
 210                 struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
 211 {
 212         struct logfs_super *super = logfs_super(sb);
 213         struct logfs_disk_super *ds;
 214         struct logfs_segment_entry se;
 215         struct page *page;
 216         u64 ofs;
 217         u32 ec, segno;
 218         int err;
 219
 220         page = find_sb(sb, &ofs);
 221         if (!page)
 222                 return -EIO;
 223         ds = page_address(page);
 224         segno = seg_no(sb, ofs);
 225         logfs_get_segment_entry(sb, segno, &se);
 226         ec = be32_to_cpu(se.ec_level) >> 4;
 227         ec++;
 228         logfs_set_segment_erased(sb, segno, ec, 0);
 229         logfs_write_ds(sb, ds, segno, ec);
 230         err = super->s_devops->write_sb(sb, page);
 231         page_cache_release(page);
 232         return err;
 233 }
 234
 235 int logfs_write_sb(struct super_block *sb)
 236 {
 237         struct logfs_super *super = logfs_super(sb);
 238         int err;
 239
 240         /* First superblock */
 241         err = write_one_sb(sb, super->s_devops->find_first_sb);
 242         if (err)
 243                 return err;
 244
 245         /* Last superblock */
 246         err = write_one_sb(sb, super->s_devops->find_last_sb);
 247         if (err)
 248                 return err;
 249         return 0;
 250 }
 251
 252 static int ds_cmp(const void *ds0, const void *ds1)
 253 {
 254         size_t len = sizeof(struct logfs_disk_super);
 255
 256         /* We know the segment headers differ, so ignore them */
 257         len -= LOGFS_SEGMENT_HEADERSIZE;
 258         ds0 += LOGFS_SEGMENT_HEADERSIZE;
 259         ds1 += LOGFS_SEGMENT_HEADERSIZE;
 260         return memcmp(ds0, ds1, len);
 261 }
 262
 263 static int logfs_recover_sb(struct super_block *sb)
 264 {
 265         struct logfs_super *super = logfs_super(sb);
 266         struct logfs_disk_super _ds0, *ds0 = &_ds0;
 267         struct logfs_disk_super _ds1, *ds1 = &_ds1;
 268         int err, valid0, valid1;
 269
 270         /* read first superblock */
 271         err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
 272         if (err)
 273                 return err;
 274         /* read last superblock */
 275         err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
 276         if (err)
 277                 return err;
 278         valid0 = logfs_check_ds(ds0) == 0;
 279         valid1 = logfs_check_ds(ds1) == 0;
 280
 281         if (!valid0 && valid1) {
 282                 printk(KERN_INFO"First superblock is invalid - fixing.\n");
 283                 return write_one_sb(sb, super->s_devops->find_first_sb);
 284         }
 285         if (valid0 && !valid1) {
 286                 printk(KERN_INFO"Last superblock is invalid - fixing.\n");
 287                 return write_one_sb(sb, super->s_devops->find_last_sb);
 288         }
 289         if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
 290                 printk(KERN_INFO"Superblocks don't match - fixing.\n");
 291                 return logfs_write_sb(sb);
 292         }
 293         /* If neither is valid now, something's wrong.  Didn't we properly
 294          * check them before?!? */
 295         BUG_ON(!valid0 && !valid1);
 296         return 0;
 297 }
 298
 299 static int logfs_make_writeable(struct super_block *sb)
 300 {
 301         int err;
 302
 303         err = logfs_open_segfile(sb);
 304         if (err)
 305                 return err;
 306
 307         /* Repair any broken superblock copies */
 308         err = logfs_recover_sb(sb);
 309         if (err)
 310                 return err;
 311
 312         /* Check areas for trailing unaccounted data */
 313         err = logfs_check_areas(sb);
 314         if (err)
 315                 return err;
 316
 317         /* Do one GC pass before any data gets dirtied */
 318         logfs_gc_pass(sb);
 319
 320         /* after all initializations are done, replay the journal
 321          * for rw-mounts, if necessary */
 322         err = logfs_replay_journal(sb);
 323         if (err)
 324                 return err;
 325
 326         return 0;
 327 }
 328
 329 static int logfs_get_sb_final(struct super_block *sb)
 330 {
 331         struct logfs_super *super = logfs_super(sb);
 332         struct inode *rootdir;
 333         int err;
 334
 335         /* root dir */
 336         rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
 337         if (IS_ERR(rootdir))
 338                 goto fail;
 339
 340         sb->s_root = d_alloc_root(rootdir);
 341         if (!sb->s_root) {
 342                 iput(rootdir);
 343                 goto fail;
 344         }
 345
 346         /* at that point we know that ->put_super() will be called */
 347         super->s_erase_page = alloc_pages(GFP_KERNEL, 0);
 348         if (!super->s_erase_page)
 349                 return -ENOMEM;
 350         memset(page_address(super->s_erase_page), 0xFF, PAGE_SIZE);
 351
 352         /* FIXME: check for read-only mounts */
 353         err = logfs_make_writeable(sb);
 354         if (err) {
 355                 __free_page(super->s_erase_page);
 356                 return err;
 357         }
 358
 359         log_super("LogFS: Finished mounting\n");
 360         return 0;
 361
 362 fail:
 363         iput(super->s_master_inode);
 364         iput(super->s_segfile_inode);
 365         iput(super->s_mapping_inode);
 366         return -EIO;
 367 }
 368
 369 int logfs_check_ds(struct logfs_disk_super *ds)
 370 {
 371         struct logfs_segment_header *sh = &ds->ds_sh;
 372
 373         if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
 374                 return -EINVAL;
 375         if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
 376                 return -EINVAL;
 377         if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
 378                                 LOGFS_SEGMENT_HEADERSIZE + 12))
 379                 return -EINVAL;
 380         return 0;
 381 }
 382
 383 static struct page *find_super_block(struct super_block *sb)
 384 {
 385         struct logfs_super *super = logfs_super(sb);
 386         struct page *first, *last;
 387
 388         first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
 389         if (!first || IS_ERR(first))
 390                 return NULL;
 391         last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
 392         if (!last || IS_ERR(last)) {
 393                 page_cache_release(first);
 394                 return NULL;
 395         }
 396
 397         if (!logfs_check_ds(page_address(first))) {
 398                 page_cache_release(last);
 399                 return first;
 400         }
 401
 402         /* First one didn't work, try the second superblock */
 403         if (!logfs_check_ds(page_address(last))) {
 404                 page_cache_release(first);
 405                 return last;
 406         }
 407
 408         /* Neither worked, sorry folks */
 409         page_cache_release(first);
 410         page_cache_release(last);
 411         return NULL;
 412 }
 413
 414 static int __logfs_read_sb(struct super_block *sb)
 415 {
 416         struct logfs_super *super = logfs_super(sb);
 417         struct page *page;
 418         struct logfs_disk_super *ds;
 419         int i;
 420
 421         page = find_super_block(sb);
 422         if (!page)
 423                 return -EINVAL;
 424
 425         ds = page_address(page);
 426         super->s_size = be64_to_cpu(ds->ds_filesystem_size);
 427         super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
 428         super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
 429         super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
 430         super->s_segsize = 1 << ds->ds_segment_shift;
 431         super->s_segmask = (1 << ds->ds_segment_shift) - 1;
 432         super->s_segshift = ds->ds_segment_shift;
 433         sb->s_blocksize = 1 << ds->ds_block_shift;
 434         sb->s_blocksize_bits = ds->ds_block_shift;
 435         super->s_writesize = 1 << ds->ds_write_shift;
 436         super->s_writeshift = ds->ds_write_shift;
 437         super->s_no_segs = super->s_size >> super->s_segshift;
 438         super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
 439         super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
 440         super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
 441         super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
 442         super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
 443
 444         journal_for_each(i)
 445                 super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
 446
 447         super->s_ifile_levels = ds->ds_ifile_levels;
 448         super->s_iblock_levels = ds->ds_iblock_levels;
 449         super->s_data_levels = ds->ds_data_levels;
 450         super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
 451                 + super->s_data_levels;
 452         page_cache_release(page);
 453         return 0;
 454 }
 455
 456 static int logfs_read_sb(struct super_block *sb, int read_only)
 457 {
 458         struct logfs_super *super = logfs_super(sb);
 459         int ret;
 460
 461         super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
 462         if (!super->s_btree_pool)
 463                 return -ENOMEM;
 464
 465         btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
 466         btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
 467         btree_init_mempool32(&super->s_shadow_tree.segment_map,
 468                         super->s_btree_pool);
 469
 470         ret = logfs_init_mapping(sb);
 471         if (ret)
 472                 return ret;
 473
 474         ret = __logfs_read_sb(sb);
 475         if (ret)
 476                 return ret;
 477
 478         if (super->s_feature_incompat & ~LOGFS_FEATURES_INCOMPAT)
 479                 return -EIO;
 480         if ((super->s_feature_ro_compat & ~LOGFS_FEATURES_RO_COMPAT) &&
 481                         !read_only)
 482                 return -EIO;
 483
 484         ret = logfs_init_rw(sb);
 485         if (ret)
 486                 return ret;
 487
 488         ret = logfs_init_areas(sb);
 489         if (ret)
 490                 return ret;
 491
 492         ret = logfs_init_gc(sb);
 493         if (ret)
 494                 return ret;
 495
 496         ret = logfs_init_journal(sb);
 497         if (ret)
 498                 return ret;
 499
 500         return 0;
 501 }
 502
 503 static void logfs_kill_sb(struct super_block *sb)
 504 {
 505         struct logfs_super *super = logfs_super(sb);
 506
 507         log_super("LogFS: Start unmounting\n");
 508         /* Alias entries slow down mount, so evict as many as possible */
 509         sync_filesystem(sb);
 510         logfs_write_anchor(sb);
 511         free_areas(sb);
 512
 513         /*
 514          * From this point on alias entries are simply dropped - and any
 515          * writes to the object store are considered bugs.
 516          */
 517         super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
 518         log_super("LogFS: Now in shutdown\n");
 519         generic_shutdown_super(sb);
 520
 521         BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
 522
 523         logfs_cleanup_gc(sb);
 524         logfs_cleanup_journal(sb);
 525         logfs_cleanup_areas(sb);
 526         logfs_cleanup_rw(sb);
 527         if (super->s_erase_page)
 528                 __free_page(super->s_erase_page);
 529         super->s_devops->put_device(super);
 530         logfs_mempool_destroy(super->s_btree_pool);
 531         logfs_mempool_destroy(super->s_alias_pool);
 532         kfree(super);
 533         log_super("LogFS: Finished unmounting\n");
 534 }
 535
 536 static struct dentry *logfs_get_sb_device(struct logfs_super *super,
 537                 struct file_system_type *type, int flags)
 538 {
 539         struct super_block *sb;
 540         int err = -ENOMEM;
 541         static int mount_count;
 542
 543         log_super("LogFS: Start mount %x\n", mount_count++);
 544
 545         err = -EINVAL;
 546         sb = sget(type, logfs_sb_test, logfs_sb_set, super);
 547         if (IS_ERR(sb)) {
 548                 super->s_devops->put_device(super);
 549                 kfree(super);
 550                 return ERR_CAST(sb);
 551         }
 552
 553         if (sb->s_root) {
 554                 /* Device is already in use */
 555                 super->s_devops->put_device(super);
 556                 kfree(super);
 557                 return dget(sb->s_root);
 558         }
 559
 560         /*
 561          * sb->s_maxbytes is limited to 8TB.  On 32bit systems, the page cache
 562          * only covers 16TB and the upper 8TB are used for indirect blocks.
 563          * On 64bit system we could bump up the limit, but that would make
 564          * the filesystem incompatible with 32bit systems.
 565          */
 566         sb->s_maxbytes  = (1ull << 43) - 1;
 567         sb->s_op        = &logfs_super_operations;
 568         sb->s_flags     = flags | MS_NOATIME;
 569
 570         err = logfs_read_sb(sb, sb->s_flags & MS_RDONLY);
 571         if (err)
 572                 goto err1;
 573
 574         sb->s_flags |= MS_ACTIVE;
 575         err = logfs_get_sb_final(sb);
 576         if (err) {
 577                 deactivate_locked_super(sb);
 578                 return ERR_PTR(err);
 579         }
 580         return dget(sb->s_root);
 581
 582 err1:
 583         /* no ->s_root, no ->put_super() */
 584         iput(super->s_master_inode);
 585         iput(super->s_segfile_inode);
 586         iput(super->s_mapping_inode);
 587         deactivate_locked_super(sb);
 588         return ERR_PTR(err);
 589 }
 590
 591 static struct dentry *logfs_mount(struct file_system_type *type, int flags,
 592                 const char *devname, void *data)
 593 {
 594         ulong mtdnr;
 595         struct logfs_super *super;
 596         int err;
 597
 598         super = kzalloc(sizeof(*super), GFP_KERNEL);
 599         if (!super)
 600                 return ERR_PTR(-ENOMEM);
 601
 602         mutex_init(&super->s_dirop_mutex);
 603         mutex_init(&super->s_object_alias_mutex);
 604         INIT_LIST_HEAD(&super->s_freeing_list);
 605
 606         if (!devname)
 607                 err = logfs_get_sb_bdev(super, type, devname);
 608         else if (strncmp(devname, "mtd", 3))
 609                 err = logfs_get_sb_bdev(super, type, devname);
 610         else {
 611                 char *garbage;
 612                 mtdnr = simple_strtoul(devname+3, &garbage, 0);
 613                 if (*garbage)
 614                         err = -EINVAL;
 615                 else
 616                         err = logfs_get_sb_mtd(super, mtdnr);
 617         }
 618
 619         if (err) {
 620                 kfree(super);
 621                 return ERR_PTR(err);
 622         }
 623
 624         return logfs_get_sb_device(super, type, flags);
 625 }
 626
 627 static struct file_system_type logfs_fs_type = {
 628         .owner          = THIS_MODULE,
 629         .name           = "logfs",
 630         .mount          = logfs_mount,
 631         .kill_sb        = logfs_kill_sb,
 632         .fs_flags       = FS_REQUIRES_DEV,
 633
 634 };
 635
 636 static int __init logfs_init(void)
 637 {
 638         int ret;
 639
 640         emergency_page = alloc_pages(GFP_KERNEL, 0);
 641         if (!emergency_page)
 642                 return -ENOMEM;
 643
 644         ret = logfs_compr_init();
 645         if (ret)
 646                 goto out1;
 647
 648         ret = logfs_init_inode_cache();
 649         if (ret)
 650                 goto out2;
 651
 652         return register_filesystem(&logfs_fs_type);
 653 out2:
 654         logfs_compr_exit();
 655 out1:
 656         __free_pages(emergency_page, 0);
 657         return ret;
 658 }
 659
 660 static void __exit logfs_exit(void)
 661 {
 662         unregister_filesystem(&logfs_fs_type);
 663         logfs_destroy_inode_cache();
 664         logfs_compr_exit();
 665         __free_pages(emergency_page, 0);
 666 }
 667
 668 module_init(logfs_init);
 669 module_exit(logfs_exit);
 670
 671 MODULE_LICENSE("GPL v2");
 672 MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
 673 MODULE_DESCRIPTION("scalable flash filesystem");