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