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