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