fs/nilfs2/the_nilfs.c

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