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