fs/nilfs2/the_nilfs.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * the_nilfs shared structure.
   4  *
   5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   6  *
   7  * Written by Ryusuke Konishi.
   8  *
   9  */
  10
  11 #include <linux/buffer_head.h>
  12 #include <linux/slab.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/backing-dev.h>
  15 #include <linux/random.h>
  16 #include <linux/log2.h>
  17 #include <linux/crc32.h>
  18 #include "nilfs.h"
  19 #include "segment.h"
  20 #include "alloc.h"
  21 #include "cpfile.h"
  22 #include "sufile.h"
  23 #include "dat.h"
  24 #include "segbuf.h"
  25
  26
  27 static int nilfs_valid_sb(struct nilfs_super_block *sbp);
  28
  29 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  30                             sector_t start_blocknr, u64 seq, __u64 cno)
  31 {
  32         spin_lock(&nilfs->ns_last_segment_lock);
  33         nilfs->ns_last_pseg = start_blocknr;
  34         nilfs->ns_last_seq = seq;
  35         nilfs->ns_last_cno = cno;
  36
  37         if (!nilfs_sb_dirty(nilfs)) {
  38                 if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
  39                         goto stay_cursor;
  40
  41                 set_nilfs_sb_dirty(nilfs);
  42         }
  43         nilfs->ns_prev_seq = nilfs->ns_last_seq;
  44
  45  stay_cursor:
  46         spin_unlock(&nilfs->ns_last_segment_lock);
  47 }
  48
  49 /**
  50  * alloc_nilfs - allocate a nilfs object
  51  * @sb: super block instance
  52  *
  53  * Return Value: On success, pointer to the_nilfs is returned.
  54  * On error, NULL is returned.
  55  */
  56 struct the_nilfs *alloc_nilfs(struct super_block *sb)
  57 {
  58         struct the_nilfs *nilfs;
  59
  60         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  61         if (!nilfs)
  62                 return NULL;
  63
  64         nilfs->ns_sb = sb;
  65         nilfs->ns_bdev = sb->s_bdev;
  66         atomic_set(&nilfs->ns_ndirtyblks, 0);
  67         init_rwsem(&nilfs->ns_sem);
  68         mutex_init(&nilfs->ns_snapshot_mount_mutex);
  69         INIT_LIST_HEAD(&nilfs->ns_dirty_files);
  70         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
  71         spin_lock_init(&nilfs->ns_inode_lock);
  72         spin_lock_init(&nilfs->ns_next_gen_lock);
  73         spin_lock_init(&nilfs->ns_last_segment_lock);
  74         nilfs->ns_cptree = RB_ROOT;
  75         spin_lock_init(&nilfs->ns_cptree_lock);
  76         init_rwsem(&nilfs->ns_segctor_sem);
  77         nilfs->ns_sb_update_freq = NILFS_SB_FREQ;
  78
  79         return nilfs;
  80 }
  81
  82 /**
  83  * destroy_nilfs - destroy nilfs object
  84  * @nilfs: nilfs object to be released
  85  */
  86 void destroy_nilfs(struct the_nilfs *nilfs)
  87 {
  88         might_sleep();
  89         if (nilfs_init(nilfs)) {
  90                 nilfs_sysfs_delete_device_group(nilfs);
  91                 brelse(nilfs->ns_sbh[0]);
  92                 brelse(nilfs->ns_sbh[1]);
  93         }
  94         kfree(nilfs);
  95 }
  96
  97 static int nilfs_load_super_root(struct the_nilfs *nilfs,
  98                                  struct super_block *sb, sector_t sr_block)
  99 {
 100         struct buffer_head *bh_sr;
 101         struct nilfs_super_root *raw_sr;
 102         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 103         struct nilfs_inode *rawi;
 104         unsigned int dat_entry_size, segment_usage_size, checkpoint_size;
 105         unsigned int inode_size;
 106         int err;
 107
 108         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
 109         if (unlikely(err))
 110                 return err;
 111
 112         down_read(&nilfs->ns_sem);
 113         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 114         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 115         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 116         up_read(&nilfs->ns_sem);
 117
 118         inode_size = nilfs->ns_inode_size;
 119
 120         rawi = (void *)bh_sr->b_data + NILFS_SR_DAT_OFFSET(inode_size);
 121         err = nilfs_dat_read(sb, dat_entry_size, rawi, &nilfs->ns_dat);
 122         if (err)
 123                 goto failed;
 124
 125         rawi = (void *)bh_sr->b_data + NILFS_SR_CPFILE_OFFSET(inode_size);
 126         err = nilfs_cpfile_read(sb, checkpoint_size, rawi, &nilfs->ns_cpfile);
 127         if (err)
 128                 goto failed_dat;
 129
 130         rawi = (void *)bh_sr->b_data + NILFS_SR_SUFILE_OFFSET(inode_size);
 131         err = nilfs_sufile_read(sb, segment_usage_size, rawi,
 132                                 &nilfs->ns_sufile);
 133         if (err)
 134                 goto failed_cpfile;
 135
 136         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 137         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 138
 139  failed:
 140         brelse(bh_sr);
 141         return err;
 142
 143  failed_cpfile:
 144         iput(nilfs->ns_cpfile);
 145
 146  failed_dat:
 147         iput(nilfs->ns_dat);
 148         goto failed;
 149 }
 150
 151 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 152 {
 153         memset(ri, 0, sizeof(*ri));
 154         INIT_LIST_HEAD(&ri->ri_used_segments);
 155 }
 156
 157 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 158 {
 159         nilfs_dispose_segment_list(&ri->ri_used_segments);
 160 }
 161
 162 /**
 163  * nilfs_store_log_cursor - load log cursor from a super block
 164  * @nilfs: nilfs object
 165  * @sbp: buffer storing super block to be read
 166  *
 167  * nilfs_store_log_cursor() reads the last position of the log
 168  * containing a super root from a given super block, and initializes
 169  * relevant information on the nilfs object preparatory for log
 170  * scanning and recovery.
 171  */
 172 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
 173                                   struct nilfs_super_block *sbp)
 174 {
 175         int ret = 0;
 176
 177         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 178         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 179         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 180
 181         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 182         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 183         nilfs->ns_segnum =
 184                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 185         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 186         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 187                 nilfs_err(nilfs->ns_sb,
 188                           "pointed segment number is out of range: segnum=%llu, nsegments=%lu",
 189                           (unsigned long long)nilfs->ns_segnum,
 190                           nilfs->ns_nsegments);
 191                 ret = -EINVAL;
 192         }
 193         return ret;
 194 }
 195
 196 /**
 197  * nilfs_get_blocksize - get block size from raw superblock data
 198  * @sb: super block instance
 199  * @sbp: superblock raw data buffer
 200  * @blocksize: place to store block size
 201  *
 202  * nilfs_get_blocksize() calculates the block size from the block size
 203  * exponent information written in @sbp and stores it in @blocksize,
 204  * or aborts with an error message if it's too large.
 205  *
 206  * Return Value: On success, 0 is returned. If the block size is too
 207  * large, -EINVAL is returned.
 208  */
 209 static int nilfs_get_blocksize(struct super_block *sb,
 210                                struct nilfs_super_block *sbp, int *blocksize)
 211 {
 212         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
 213
 214         if (unlikely(shift_bits >
 215                      ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)) {
 216                 nilfs_err(sb, "too large filesystem blocksize: 2 ^ %u KiB",
 217                           shift_bits);
 218                 return -EINVAL;
 219         }
 220         *blocksize = BLOCK_SIZE << shift_bits;
 221         return 0;
 222 }
 223
 224 /**
 225  * load_nilfs - load and recover the nilfs
 226  * @nilfs: the_nilfs structure to be released
 227  * @sb: super block instance used to recover past segment
 228  *
 229  * load_nilfs() searches and load the latest super root,
 230  * attaches the last segment, and does recovery if needed.
 231  * The caller must call this exclusively for simultaneous mounts.
 232  */
 233 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
 234 {
 235         struct nilfs_recovery_info ri;
 236         unsigned int s_flags = sb->s_flags;
 237         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 238         int valid_fs = nilfs_valid_fs(nilfs);
 239         int err;
 240
 241         if (!valid_fs) {
 242                 nilfs_warn(sb, "mounting unchecked fs");
 243                 if (s_flags & SB_RDONLY) {
 244                         nilfs_info(sb,
 245                                    "recovery required for readonly filesystem");
 246                         nilfs_info(sb,
 247                                    "write access will be enabled during recovery");
 248                 }
 249         }
 250
 251         nilfs_init_recovery_info(&ri);
 252
 253         err = nilfs_search_super_root(nilfs, &ri);
 254         if (unlikely(err)) {
 255                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 256                 int blocksize;
 257
 258                 if (err != -EINVAL)
 259                         goto scan_error;
 260
 261                 if (!nilfs_valid_sb(sbp[1])) {
 262                         nilfs_warn(sb,
 263                                    "unable to fall back to spare super block");
 264                         goto scan_error;
 265                 }
 266                 nilfs_info(sb, "trying rollback from an earlier position");
 267
 268                 /*
 269                  * restore super block with its spare and reconfigure
 270                  * relevant states of the nilfs object.
 271                  */
 272                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 273                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 274                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 275
 276                 /* verify consistency between two super blocks */
 277                 err = nilfs_get_blocksize(sb, sbp[0], &blocksize);
 278                 if (err)
 279                         goto scan_error;
 280
 281                 if (blocksize != nilfs->ns_blocksize) {
 282                         nilfs_warn(sb,
 283                                    "blocksize differs between two super blocks (%d != %d)",
 284                                    blocksize, nilfs->ns_blocksize);
 285                         err = -EINVAL;
 286                         goto scan_error;
 287                 }
 288
 289                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 290                 if (err)
 291                         goto scan_error;
 292
 293                 /* drop clean flag to allow roll-forward and recovery */
 294                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 295                 valid_fs = 0;
 296
 297                 err = nilfs_search_super_root(nilfs, &ri);
 298                 if (err)
 299                         goto scan_error;
 300         }
 301
 302         err = nilfs_load_super_root(nilfs, sb, ri.ri_super_root);
 303         if (unlikely(err)) {
 304                 nilfs_err(sb, "error %d while loading super root", err);
 305                 goto failed;
 306         }
 307
 308         if (valid_fs)
 309                 goto skip_recovery;
 310
 311         if (s_flags & SB_RDONLY) {
 312                 __u64 features;
 313
 314                 if (nilfs_test_opt(nilfs, NORECOVERY)) {
 315                         nilfs_info(sb,
 316                                    "norecovery option specified, skipping roll-forward recovery");
 317                         goto skip_recovery;
 318                 }
 319                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 320                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 321                 if (features) {
 322                         nilfs_err(sb,
 323                                   "couldn't proceed with recovery because of unsupported optional features (%llx)",
 324                                   (unsigned long long)features);
 325                         err = -EROFS;
 326                         goto failed_unload;
 327                 }
 328                 if (really_read_only) {
 329                         nilfs_err(sb,
 330                                   "write access unavailable, cannot proceed");
 331                         err = -EROFS;
 332                         goto failed_unload;
 333                 }
 334                 sb->s_flags &= ~SB_RDONLY;
 335         } else if (nilfs_test_opt(nilfs, NORECOVERY)) {
 336                 nilfs_err(sb,
 337                           "recovery cancelled because norecovery option was specified for a read/write mount");
 338                 err = -EINVAL;
 339                 goto failed_unload;
 340         }
 341
 342         err = nilfs_salvage_orphan_logs(nilfs, sb, &ri);
 343         if (err)
 344                 goto failed_unload;
 345
 346         down_write(&nilfs->ns_sem);
 347         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 348         err = nilfs_cleanup_super(sb);
 349         up_write(&nilfs->ns_sem);
 350
 351         if (err) {
 352                 nilfs_err(sb,
 353                           "error %d updating super block. recovery unfinished.",
 354                           err);
 355                 goto failed_unload;
 356         }
 357         nilfs_info(sb, "recovery complete");
 358
 359  skip_recovery:
 360         nilfs_clear_recovery_info(&ri);
 361         sb->s_flags = s_flags;
 362         return 0;
 363
 364  scan_error:
 365         nilfs_err(sb, "error %d while searching super root", err);
 366         goto failed;
 367
 368  failed_unload:
 369         iput(nilfs->ns_cpfile);
 370         iput(nilfs->ns_sufile);
 371         iput(nilfs->ns_dat);
 372
 373  failed:
 374         nilfs_clear_recovery_info(&ri);
 375         sb->s_flags = s_flags;
 376         return err;
 377 }
 378
 379 static unsigned long long nilfs_max_size(unsigned int blkbits)
 380 {
 381         unsigned int max_bits;
 382         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 383
 384         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 385         if (max_bits < 64)
 386                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 387         return res;
 388 }
 389
 390 /**
 391  * nilfs_nrsvsegs - calculate the number of reserved segments
 392  * @nilfs: nilfs object
 393  * @nsegs: total number of segments
 394  */
 395 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs)
 396 {
 397         return max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 398                      DIV_ROUND_UP(nsegs * nilfs->ns_r_segments_percentage,
 399                                   100));
 400 }
 401
 402 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
 403 {
 404         nilfs->ns_nsegments = nsegs;
 405         nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
 406 }
 407
 408 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 409                                    struct nilfs_super_block *sbp)
 410 {
 411         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 412                 nilfs_err(nilfs->ns_sb,
 413                           "unsupported revision (superblock rev.=%d.%d, current rev.=%d.%d). Please check the version of mkfs.nilfs(2).",
 414                           le32_to_cpu(sbp->s_rev_level),
 415                           le16_to_cpu(sbp->s_minor_rev_level),
 416                           NILFS_CURRENT_REV, NILFS_MINOR_REV);
 417                 return -EINVAL;
 418         }
 419         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 420         if (nilfs->ns_sbsize > BLOCK_SIZE)
 421                 return -EINVAL;
 422
 423         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 424         if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
 425                 nilfs_err(nilfs->ns_sb, "too large inode size: %d bytes",
 426                           nilfs->ns_inode_size);
 427                 return -EINVAL;
 428         } else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
 429                 nilfs_err(nilfs->ns_sb, "too small inode size: %d bytes",
 430                           nilfs->ns_inode_size);
 431                 return -EINVAL;
 432         }
 433
 434         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 435
 436         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 437         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 438                 nilfs_err(nilfs->ns_sb, "too short segment: %lu blocks",
 439                           nilfs->ns_blocks_per_segment);
 440                 return -EINVAL;
 441         }
 442
 443         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 444         nilfs->ns_r_segments_percentage =
 445                 le32_to_cpu(sbp->s_r_segments_percentage);
 446         if (nilfs->ns_r_segments_percentage < 1 ||
 447             nilfs->ns_r_segments_percentage > 99) {
 448                 nilfs_err(nilfs->ns_sb,
 449                           "invalid reserved segments percentage: %lu",
 450                           nilfs->ns_r_segments_percentage);
 451                 return -EINVAL;
 452         }
 453
 454         nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments));
 455         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 456         return 0;
 457 }
 458
 459 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 460 {
 461         static unsigned char sum[4];
 462         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 463         size_t bytes;
 464         u32 crc;
 465
 466         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 467                 return 0;
 468         bytes = le16_to_cpu(sbp->s_bytes);
 469         if (bytes < sumoff + 4 || bytes > BLOCK_SIZE)
 470                 return 0;
 471         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 472                        sumoff);
 473         crc = crc32_le(crc, sum, 4);
 474         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 475                        bytes - sumoff - 4);
 476         return crc == le32_to_cpu(sbp->s_sum);
 477 }
 478
 479 /**
 480  * nilfs_sb2_bad_offset - check the location of the second superblock
 481  * @sbp: superblock raw data buffer
 482  * @offset: byte offset of second superblock calculated from device size
 483  *
 484  * nilfs_sb2_bad_offset() checks if the position on the second
 485  * superblock is valid or not based on the filesystem parameters
 486  * stored in @sbp.  If @offset points to a location within the segment
 487  * area, or if the parameters themselves are not normal, it is
 488  * determined to be invalid.
 489  *
 490  * Return Value: true if invalid, false if valid.
 491  */
 492 static bool nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 493 {
 494         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
 495         u32 blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 496         u64 nsegments = le64_to_cpu(sbp->s_nsegments);
 497         u64 index;
 498
 499         if (blocks_per_segment < NILFS_SEG_MIN_BLOCKS ||
 500             shift_bits > ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)
 501                 return true;
 502
 503         index = offset >> (shift_bits + BLOCK_SIZE_BITS);
 504         do_div(index, blocks_per_segment);
 505         return index < nsegments;
 506 }
 507
 508 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 509 {
 510         int i;
 511
 512         for (i = 0; i < 2; i++) {
 513                 if (nilfs->ns_sbp[i]) {
 514                         brelse(nilfs->ns_sbh[i]);
 515                         nilfs->ns_sbh[i] = NULL;
 516                         nilfs->ns_sbp[i] = NULL;
 517                 }
 518         }
 519 }
 520
 521 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 522 {
 523         brelse(nilfs->ns_sbh[0]);
 524         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 525         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 526         nilfs->ns_sbh[1] = NULL;
 527         nilfs->ns_sbp[1] = NULL;
 528 }
 529
 530 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 531 {
 532         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 533         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 534
 535         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 536         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 537         nilfs->ns_sbh[1] = tsbh;
 538         nilfs->ns_sbp[1] = tsbp;
 539 }
 540
 541 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 542                                   struct super_block *sb, int blocksize,
 543                                   struct nilfs_super_block **sbpp)
 544 {
 545         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 546         struct buffer_head **sbh = nilfs->ns_sbh;
 547         u64 sb2off, devsize = bdev_nr_bytes(nilfs->ns_bdev);
 548         int valid[2], swp = 0;
 549
 550         if (devsize < NILFS_SEG_MIN_BLOCKS * NILFS_MIN_BLOCK_SIZE + 4096) {
 551                 nilfs_err(sb, "device size too small");
 552                 return -EINVAL;
 553         }
 554         sb2off = NILFS_SB2_OFFSET_BYTES(devsize);
 555
 556         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 557                                         &sbh[0]);
 558         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 559
 560         if (!sbp[0]) {
 561                 if (!sbp[1]) {
 562                         nilfs_err(sb, "unable to read superblock");
 563                         return -EIO;
 564                 }
 565                 nilfs_warn(sb,
 566                            "unable to read primary superblock (blocksize = %d)",
 567                            blocksize);
 568         } else if (!sbp[1]) {
 569                 nilfs_warn(sb,
 570                            "unable to read secondary superblock (blocksize = %d)",
 571                            blocksize);
 572         }
 573
 574         /*
 575          * Compare two super blocks and set 1 in swp if the secondary
 576          * super block is valid and newer.  Otherwise, set 0 in swp.
 577          */
 578         valid[0] = nilfs_valid_sb(sbp[0]);
 579         valid[1] = nilfs_valid_sb(sbp[1]);
 580         swp = valid[1] && (!valid[0] ||
 581                            le64_to_cpu(sbp[1]->s_last_cno) >
 582                            le64_to_cpu(sbp[0]->s_last_cno));
 583
 584         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 585                 brelse(sbh[1]);
 586                 sbh[1] = NULL;
 587                 sbp[1] = NULL;
 588                 valid[1] = 0;
 589                 swp = 0;
 590         }
 591         if (!valid[swp]) {
 592                 nilfs_release_super_block(nilfs);
 593                 nilfs_err(sb, "couldn't find nilfs on the device");
 594                 return -EINVAL;
 595         }
 596
 597         if (!valid[!swp])
 598                 nilfs_warn(sb,
 599                            "broken superblock, retrying with spare superblock (blocksize = %d)",
 600                            blocksize);
 601         if (swp)
 602                 nilfs_swap_super_block(nilfs);
 603
 604         nilfs->ns_sbwcount = 0;
 605         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 606         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 607         *sbpp = sbp[0];
 608         return 0;
 609 }
 610
 611 /**
 612  * init_nilfs - initialize a NILFS instance.
 613  * @nilfs: the_nilfs structure
 614  * @sb: super block
 615  * @data: mount options
 616  *
 617  * init_nilfs() performs common initialization per block device (e.g.
 618  * reading the super block, getting disk layout information, initializing
 619  * shared fields in the_nilfs).
 620  *
 621  * Return Value: On success, 0 is returned. On error, a negative error
 622  * code is returned.
 623  */
 624 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data)
 625 {
 626         struct nilfs_super_block *sbp;
 627         int blocksize;
 628         int err;
 629
 630         down_write(&nilfs->ns_sem);
 631
 632         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 633         if (!blocksize) {
 634                 nilfs_err(sb, "unable to set blocksize");
 635                 err = -EINVAL;
 636                 goto out;
 637         }
 638         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 639         if (err)
 640                 goto out;
 641
 642         err = nilfs_store_magic_and_option(sb, sbp, data);
 643         if (err)
 644                 goto failed_sbh;
 645
 646         err = nilfs_check_feature_compatibility(sb, sbp);
 647         if (err)
 648                 goto failed_sbh;
 649
 650         err = nilfs_get_blocksize(sb, sbp, &blocksize);
 651         if (err)
 652                 goto failed_sbh;
 653
 654         if (blocksize < NILFS_MIN_BLOCK_SIZE) {
 655                 nilfs_err(sb,
 656                           "couldn't mount because of unsupported filesystem blocksize %d",
 657                           blocksize);
 658                 err = -EINVAL;
 659                 goto failed_sbh;
 660         }
 661         if (sb->s_blocksize != blocksize) {
 662                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 663
 664                 if (blocksize < hw_blocksize) {
 665                         nilfs_err(sb,
 666                                   "blocksize %d too small for device (sector-size = %d)",
 667                                   blocksize, hw_blocksize);
 668                         err = -EINVAL;
 669                         goto failed_sbh;
 670                 }
 671                 nilfs_release_super_block(nilfs);
 672                 sb_set_blocksize(sb, blocksize);
 673
 674                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 675                 if (err)
 676                         goto out;
 677                         /*
 678                          * Not to failed_sbh; sbh is released automatically
 679                          * when reloading fails.
 680                          */
 681         }
 682         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 683         nilfs->ns_blocksize = blocksize;
 684
 685         get_random_bytes(&nilfs->ns_next_generation,
 686                          sizeof(nilfs->ns_next_generation));
 687
 688         err = nilfs_store_disk_layout(nilfs, sbp);
 689         if (err)
 690                 goto failed_sbh;
 691
 692         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 693
 694         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 695
 696         err = nilfs_store_log_cursor(nilfs, sbp);
 697         if (err)
 698                 goto failed_sbh;
 699
 700         err = nilfs_sysfs_create_device_group(sb);
 701         if (err)
 702                 goto failed_sbh;
 703
 704         set_nilfs_init(nilfs);
 705         err = 0;
 706  out:
 707         up_write(&nilfs->ns_sem);
 708         return err;
 709
 710  failed_sbh:
 711         nilfs_release_super_block(nilfs);
 712         goto out;
 713 }
 714
 715 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 716                             size_t nsegs)
 717 {
 718         sector_t seg_start, seg_end;
 719         sector_t start = 0, nblocks = 0;
 720         unsigned int sects_per_block;
 721         __u64 *sn;
 722         int ret = 0;
 723
 724         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 725                 bdev_logical_block_size(nilfs->ns_bdev);
 726         for (sn = segnump; sn < segnump + nsegs; sn++) {
 727                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 728
 729                 if (!nblocks) {
 730                         start = seg_start;
 731                         nblocks = seg_end - seg_start + 1;
 732                 } else if (start + nblocks == seg_start) {
 733                         nblocks += seg_end - seg_start + 1;
 734                 } else {
 735                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 736                                                    start * sects_per_block,
 737                                                    nblocks * sects_per_block,
 738                                                    GFP_NOFS);
 739                         if (ret < 0)
 740                                 return ret;
 741                         nblocks = 0;
 742                 }
 743         }
 744         if (nblocks)
 745                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 746                                            start * sects_per_block,
 747                                            nblocks * sects_per_block,
 748                                            GFP_NOFS);
 749         return ret;
 750 }
 751
 752 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 753 {
 754         unsigned long ncleansegs;
 755
 756         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 757         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 758         return 0;
 759 }
 760
 761 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 762 {
 763         unsigned long ncleansegs, nincsegs;
 764
 765         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 766         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 767                 nilfs->ns_blocks_per_segment + 1;
 768
 769         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 770 }
 771
 772 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 773 {
 774         struct rb_node *n;
 775         struct nilfs_root *root;
 776
 777         spin_lock(&nilfs->ns_cptree_lock);
 778         n = nilfs->ns_cptree.rb_node;
 779         while (n) {
 780                 root = rb_entry(n, struct nilfs_root, rb_node);
 781
 782                 if (cno < root->cno) {
 783                         n = n->rb_left;
 784                 } else if (cno > root->cno) {
 785                         n = n->rb_right;
 786                 } else {
 787                         refcount_inc(&root->count);
 788                         spin_unlock(&nilfs->ns_cptree_lock);
 789                         return root;
 790                 }
 791         }
 792         spin_unlock(&nilfs->ns_cptree_lock);
 793
 794         return NULL;
 795 }
 796
 797 struct nilfs_root *
 798 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 799 {
 800         struct rb_node **p, *parent;
 801         struct nilfs_root *root, *new;
 802         int err;
 803
 804         root = nilfs_lookup_root(nilfs, cno);
 805         if (root)
 806                 return root;
 807
 808         new = kzalloc(sizeof(*root), GFP_KERNEL);
 809         if (!new)
 810                 return NULL;
 811
 812         spin_lock(&nilfs->ns_cptree_lock);
 813
 814         p = &nilfs->ns_cptree.rb_node;
 815         parent = NULL;
 816
 817         while (*p) {
 818                 parent = *p;
 819                 root = rb_entry(parent, struct nilfs_root, rb_node);
 820
 821                 if (cno < root->cno) {
 822                         p = &(*p)->rb_left;
 823                 } else if (cno > root->cno) {
 824                         p = &(*p)->rb_right;
 825                 } else {
 826                         refcount_inc(&root->count);
 827                         spin_unlock(&nilfs->ns_cptree_lock);
 828                         kfree(new);
 829                         return root;
 830                 }
 831         }
 832
 833         new->cno = cno;
 834         new->ifile = NULL;
 835         new->nilfs = nilfs;
 836         refcount_set(&new->count, 1);
 837         atomic64_set(&new->inodes_count, 0);
 838         atomic64_set(&new->blocks_count, 0);
 839
 840         rb_link_node(&new->rb_node, parent, p);
 841         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 842
 843         spin_unlock(&nilfs->ns_cptree_lock);
 844
 845         err = nilfs_sysfs_create_snapshot_group(new);
 846         if (err) {
 847                 kfree(new);
 848                 new = NULL;
 849         }
 850
 851         return new;
 852 }
 853
 854 void nilfs_put_root(struct nilfs_root *root)
 855 {
 856         struct the_nilfs *nilfs = root->nilfs;
 857
 858         if (refcount_dec_and_lock(&root->count, &nilfs->ns_cptree_lock)) {
 859                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 860                 spin_unlock(&nilfs->ns_cptree_lock);
 861
 862                 nilfs_sysfs_delete_snapshot_group(root);
 863                 iput(root->ifile);
 864
 865                 kfree(root);
 866         }
 867 }