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                 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  * nilfs_get_blocksize - get block size from raw superblock data
 197  * @sb: super block instance
 198  * @sbp: superblock raw data buffer
 199  * @blocksize: place to store block size
 200  *
 201  * nilfs_get_blocksize() calculates the block size from the block size
 202  * exponent information written in @sbp and stores it in @blocksize,
 203  * or aborts with an error message if it's too large.
 204  *
 205  * Return Value: On success, 0 is returned. If the block size is too
 206  * large, -EINVAL is returned.
 207  */
 208 static int nilfs_get_blocksize(struct super_block *sb,
 209                                struct nilfs_super_block *sbp, int *blocksize)
 210 {
 211         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
 212
 213         if (unlikely(shift_bits >
 214                      ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)) {
 215                 nilfs_err(sb, "too large filesystem blocksize: 2 ^ %u KiB",
 216                           shift_bits);
 217                 return -EINVAL;
 218         }
 219         *blocksize = BLOCK_SIZE << shift_bits;
 220         return 0;
 221 }
 222
 223 /**
 224  * load_nilfs - load and recover the nilfs
 225  * @nilfs: the_nilfs structure to be released
 226  * @sb: super block instance used to recover past segment
 227  *
 228  * load_nilfs() searches and load the latest super root,
 229  * attaches the last segment, and does recovery if needed.
 230  * The caller must call this exclusively for simultaneous mounts.
 231  */
 232 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
 233 {
 234         struct nilfs_recovery_info ri;
 235         unsigned int s_flags = sb->s_flags;
 236         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 237         int valid_fs = nilfs_valid_fs(nilfs);
 238         int err;
 239
 240         if (!valid_fs) {
 241                 nilfs_warn(sb, "mounting unchecked fs");
 242                 if (s_flags & SB_RDONLY) {
 243                         nilfs_info(sb,
 244                                    "recovery required for readonly filesystem");
 245                         nilfs_info(sb,
 246                                    "write access will be enabled during recovery");
 247                 }
 248         }
 249
 250         nilfs_init_recovery_info(&ri);
 251
 252         err = nilfs_search_super_root(nilfs, &ri);
 253         if (unlikely(err)) {
 254                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 255                 int blocksize;
 256
 257                 if (err != -EINVAL)
 258                         goto scan_error;
 259
 260                 if (!nilfs_valid_sb(sbp[1])) {
 261                         nilfs_warn(sb,
 262                                    "unable to fall back to spare super block");
 263                         goto scan_error;
 264                 }
 265                 nilfs_info(sb, "trying rollback from an earlier position");
 266
 267                 /*
 268                  * restore super block with its spare and reconfigure
 269                  * relevant states of the nilfs object.
 270                  */
 271                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 272                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 273                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 274
 275                 /* verify consistency between two super blocks */
 276                 err = nilfs_get_blocksize(sb, sbp[0], &blocksize);
 277                 if (err)
 278                         goto scan_error;
 279
 280                 if (blocksize != nilfs->ns_blocksize) {
 281                         nilfs_warn(sb,
 282                                    "blocksize differs between two super blocks (%d != %d)",
 283                                    blocksize, nilfs->ns_blocksize);
 284                         err = -EINVAL;
 285                         goto scan_error;
 286                 }
 287
 288                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 289                 if (err)
 290                         goto scan_error;
 291
 292                 /* drop clean flag to allow roll-forward and recovery */
 293                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 294                 valid_fs = 0;
 295
 296                 err = nilfs_search_super_root(nilfs, &ri);
 297                 if (err)
 298                         goto scan_error;
 299         }
 300
 301         err = nilfs_load_super_root(nilfs, sb, ri.ri_super_root);
 302         if (unlikely(err)) {
 303                 nilfs_err(sb, "error %d while loading super root", err);
 304                 goto failed;
 305         }
 306
 307         err = nilfs_sysfs_create_device_group(sb);
 308         if (unlikely(err))
 309                 goto sysfs_error;
 310
 311         if (valid_fs)
 312                 goto skip_recovery;
 313
 314         if (s_flags & SB_RDONLY) {
 315                 __u64 features;
 316
 317                 if (nilfs_test_opt(nilfs, NORECOVERY)) {
 318                         nilfs_info(sb,
 319                                    "norecovery option specified, skipping roll-forward recovery");
 320                         goto skip_recovery;
 321                 }
 322                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 323                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 324                 if (features) {
 325                         nilfs_err(sb,
 326                                   "couldn't proceed with recovery because of unsupported optional features (%llx)",
 327                                   (unsigned long long)features);
 328                         err = -EROFS;
 329                         goto failed_unload;
 330                 }
 331                 if (really_read_only) {
 332                         nilfs_err(sb,
 333                                   "write access unavailable, cannot proceed");
 334                         err = -EROFS;
 335                         goto failed_unload;
 336                 }
 337                 sb->s_flags &= ~SB_RDONLY;
 338         } else if (nilfs_test_opt(nilfs, NORECOVERY)) {
 339                 nilfs_err(sb,
 340                           "recovery cancelled because norecovery option was specified for a read/write mount");
 341                 err = -EINVAL;
 342                 goto failed_unload;
 343         }
 344
 345         err = nilfs_salvage_orphan_logs(nilfs, sb, &ri);
 346         if (err)
 347                 goto failed_unload;
 348
 349         down_write(&nilfs->ns_sem);
 350         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 351         err = nilfs_cleanup_super(sb);
 352         up_write(&nilfs->ns_sem);
 353
 354         if (err) {
 355                 nilfs_err(sb,
 356                           "error %d updating super block. recovery unfinished.",
 357                           err);
 358                 goto failed_unload;
 359         }
 360         nilfs_info(sb, "recovery complete");
 361
 362  skip_recovery:
 363         nilfs_clear_recovery_info(&ri);
 364         sb->s_flags = s_flags;
 365         return 0;
 366
 367  scan_error:
 368         nilfs_err(sb, "error %d while searching super root", err);
 369         goto failed;
 370
 371  failed_unload:
 372         nilfs_sysfs_delete_device_group(nilfs);
 373
 374  sysfs_error:
 375         iput(nilfs->ns_cpfile);
 376         iput(nilfs->ns_sufile);
 377         iput(nilfs->ns_dat);
 378
 379  failed:
 380         nilfs_clear_recovery_info(&ri);
 381         sb->s_flags = s_flags;
 382         return err;
 383 }
 384
 385 static unsigned long long nilfs_max_size(unsigned int blkbits)
 386 {
 387         unsigned int max_bits;
 388         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 389
 390         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 391         if (max_bits < 64)
 392                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 393         return res;
 394 }
 395
 396 /**
 397  * nilfs_nrsvsegs - calculate the number of reserved segments
 398  * @nilfs: nilfs object
 399  * @nsegs: total number of segments
 400  */
 401 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs)
 402 {
 403         return max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 404                      DIV_ROUND_UP(nsegs * nilfs->ns_r_segments_percentage,
 405                                   100));
 406 }
 407
 408 /**
 409  * nilfs_max_segment_count - calculate the maximum number of segments
 410  * @nilfs: nilfs object
 411  */
 412 static u64 nilfs_max_segment_count(struct the_nilfs *nilfs)
 413 {
 414         u64 max_count = U64_MAX;
 415
 416         max_count = div64_ul(max_count, nilfs->ns_blocks_per_segment);
 417         return min_t(u64, max_count, ULONG_MAX);
 418 }
 419
 420 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
 421 {
 422         nilfs->ns_nsegments = nsegs;
 423         nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
 424 }
 425
 426 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 427                                    struct nilfs_super_block *sbp)
 428 {
 429         u64 nsegments, nblocks;
 430
 431         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 432                 nilfs_err(nilfs->ns_sb,
 433                           "unsupported revision (superblock rev.=%d.%d, current rev.=%d.%d). Please check the version of mkfs.nilfs(2).",
 434                           le32_to_cpu(sbp->s_rev_level),
 435                           le16_to_cpu(sbp->s_minor_rev_level),
 436                           NILFS_CURRENT_REV, NILFS_MINOR_REV);
 437                 return -EINVAL;
 438         }
 439         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 440         if (nilfs->ns_sbsize > BLOCK_SIZE)
 441                 return -EINVAL;
 442
 443         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 444         if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
 445                 nilfs_err(nilfs->ns_sb, "too large inode size: %d bytes",
 446                           nilfs->ns_inode_size);
 447                 return -EINVAL;
 448         } else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
 449                 nilfs_err(nilfs->ns_sb, "too small inode size: %d bytes",
 450                           nilfs->ns_inode_size);
 451                 return -EINVAL;
 452         }
 453
 454         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 455
 456         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 457         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 458                 nilfs_err(nilfs->ns_sb, "too short segment: %lu blocks",
 459                           nilfs->ns_blocks_per_segment);
 460                 return -EINVAL;
 461         }
 462
 463         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 464         nilfs->ns_r_segments_percentage =
 465                 le32_to_cpu(sbp->s_r_segments_percentage);
 466         if (nilfs->ns_r_segments_percentage < 1 ||
 467             nilfs->ns_r_segments_percentage > 99) {
 468                 nilfs_err(nilfs->ns_sb,
 469                           "invalid reserved segments percentage: %lu",
 470                           nilfs->ns_r_segments_percentage);
 471                 return -EINVAL;
 472         }
 473
 474         nsegments = le64_to_cpu(sbp->s_nsegments);
 475         if (nsegments > nilfs_max_segment_count(nilfs)) {
 476                 nilfs_err(nilfs->ns_sb,
 477                           "segment count %llu exceeds upper limit (%llu segments)",
 478                           (unsigned long long)nsegments,
 479                           (unsigned long long)nilfs_max_segment_count(nilfs));
 480                 return -EINVAL;
 481         }
 482
 483         nblocks = sb_bdev_nr_blocks(nilfs->ns_sb);
 484         if (nblocks) {
 485                 u64 min_block_count = nsegments * nilfs->ns_blocks_per_segment;
 486                 /*
 487                  * To avoid failing to mount early device images without a
 488                  * second superblock, exclude that block count from the
 489                  * "min_block_count" calculation.
 490                  */
 491
 492                 if (nblocks < min_block_count) {
 493                         nilfs_err(nilfs->ns_sb,
 494                                   "total number of segment blocks %llu exceeds device size (%llu blocks)",
 495                                   (unsigned long long)min_block_count,
 496                                   (unsigned long long)nblocks);
 497                         return -EINVAL;
 498                 }
 499         }
 500
 501         nilfs_set_nsegments(nilfs, nsegments);
 502         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 503         return 0;
 504 }
 505
 506 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 507 {
 508         static unsigned char sum[4];
 509         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 510         size_t bytes;
 511         u32 crc;
 512
 513         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 514                 return 0;
 515         bytes = le16_to_cpu(sbp->s_bytes);
 516         if (bytes < sumoff + 4 || bytes > BLOCK_SIZE)
 517                 return 0;
 518         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 519                        sumoff);
 520         crc = crc32_le(crc, sum, 4);
 521         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 522                        bytes - sumoff - 4);
 523         return crc == le32_to_cpu(sbp->s_sum);
 524 }
 525
 526 /**
 527  * nilfs_sb2_bad_offset - check the location of the second superblock
 528  * @sbp: superblock raw data buffer
 529  * @offset: byte offset of second superblock calculated from device size
 530  *
 531  * nilfs_sb2_bad_offset() checks if the position on the second
 532  * superblock is valid or not based on the filesystem parameters
 533  * stored in @sbp.  If @offset points to a location within the segment
 534  * area, or if the parameters themselves are not normal, it is
 535  * determined to be invalid.
 536  *
 537  * Return Value: true if invalid, false if valid.
 538  */
 539 static bool nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 540 {
 541         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
 542         u32 blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 543         u64 nsegments = le64_to_cpu(sbp->s_nsegments);
 544         u64 index;
 545
 546         if (blocks_per_segment < NILFS_SEG_MIN_BLOCKS ||
 547             shift_bits > ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)
 548                 return true;
 549
 550         index = offset >> (shift_bits + BLOCK_SIZE_BITS);
 551         do_div(index, blocks_per_segment);
 552         return index < nsegments;
 553 }
 554
 555 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 556 {
 557         int i;
 558
 559         for (i = 0; i < 2; i++) {
 560                 if (nilfs->ns_sbp[i]) {
 561                         brelse(nilfs->ns_sbh[i]);
 562                         nilfs->ns_sbh[i] = NULL;
 563                         nilfs->ns_sbp[i] = NULL;
 564                 }
 565         }
 566 }
 567
 568 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 569 {
 570         brelse(nilfs->ns_sbh[0]);
 571         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 572         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 573         nilfs->ns_sbh[1] = NULL;
 574         nilfs->ns_sbp[1] = NULL;
 575 }
 576
 577 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 578 {
 579         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 580         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 581
 582         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 583         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 584         nilfs->ns_sbh[1] = tsbh;
 585         nilfs->ns_sbp[1] = tsbp;
 586 }
 587
 588 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 589                                   struct super_block *sb, int blocksize,
 590                                   struct nilfs_super_block **sbpp)
 591 {
 592         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 593         struct buffer_head **sbh = nilfs->ns_sbh;
 594         u64 sb2off, devsize = bdev_nr_bytes(nilfs->ns_bdev);
 595         int valid[2], swp = 0, older;
 596
 597         if (devsize < NILFS_SEG_MIN_BLOCKS * NILFS_MIN_BLOCK_SIZE + 4096) {
 598                 nilfs_err(sb, "device size too small");
 599                 return -EINVAL;
 600         }
 601         sb2off = NILFS_SB2_OFFSET_BYTES(devsize);
 602
 603         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 604                                         &sbh[0]);
 605         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 606
 607         if (!sbp[0]) {
 608                 if (!sbp[1]) {
 609                         nilfs_err(sb, "unable to read superblock");
 610                         return -EIO;
 611                 }
 612                 nilfs_warn(sb,
 613                            "unable to read primary superblock (blocksize = %d)",
 614                            blocksize);
 615         } else if (!sbp[1]) {
 616                 nilfs_warn(sb,
 617                            "unable to read secondary superblock (blocksize = %d)",
 618                            blocksize);
 619         }
 620
 621         /*
 622          * Compare two super blocks and set 1 in swp if the secondary
 623          * super block is valid and newer.  Otherwise, set 0 in swp.
 624          */
 625         valid[0] = nilfs_valid_sb(sbp[0]);
 626         valid[1] = nilfs_valid_sb(sbp[1]);
 627         swp = valid[1] && (!valid[0] ||
 628                            le64_to_cpu(sbp[1]->s_last_cno) >
 629                            le64_to_cpu(sbp[0]->s_last_cno));
 630
 631         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 632                 brelse(sbh[1]);
 633                 sbh[1] = NULL;
 634                 sbp[1] = NULL;
 635                 valid[1] = 0;
 636                 swp = 0;
 637         }
 638         if (!valid[swp]) {
 639                 nilfs_release_super_block(nilfs);
 640                 nilfs_err(sb, "couldn't find nilfs on the device");
 641                 return -EINVAL;
 642         }
 643
 644         if (!valid[!swp])
 645                 nilfs_warn(sb,
 646                            "broken superblock, retrying with spare superblock (blocksize = %d)",
 647                            blocksize);
 648         if (swp)
 649                 nilfs_swap_super_block(nilfs);
 650
 651         /*
 652          * Calculate the array index of the older superblock data.
 653          * If one has been dropped, set index 0 pointing to the remaining one,
 654          * otherwise set index 1 pointing to the old one (including if both
 655          * are the same).
 656          *
 657          *  Divided case             valid[0]  valid[1]  swp  ->  older
 658          *  -------------------------------------------------------------
 659          *  Both SBs are invalid        0         0       N/A (Error)
 660          *  SB1 is invalid              0         1       1         0
 661          *  SB2 is invalid              1         0       0         0
 662          *  SB2 is newer                1         1       1         0
 663          *  SB2 is older or the same    1         1       0         1
 664          */
 665         older = valid[1] ^ swp;
 666
 667         nilfs->ns_sbwcount = 0;
 668         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 669         nilfs->ns_prot_seq = le64_to_cpu(sbp[older]->s_last_seq);
 670         *sbpp = sbp[0];
 671         return 0;
 672 }
 673
 674 /**
 675  * init_nilfs - initialize a NILFS instance.
 676  * @nilfs: the_nilfs structure
 677  * @sb: super block
 678  *
 679  * init_nilfs() performs common initialization per block device (e.g.
 680  * reading the super block, getting disk layout information, initializing
 681  * shared fields in the_nilfs).
 682  *
 683  * Return Value: On success, 0 is returned. On error, a negative error
 684  * code is returned.
 685  */
 686 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
 687 {
 688         struct nilfs_super_block *sbp;
 689         int blocksize;
 690         int err;
 691
 692         down_write(&nilfs->ns_sem);
 693
 694         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 695         if (!blocksize) {
 696                 nilfs_err(sb, "unable to set blocksize");
 697                 err = -EINVAL;
 698                 goto out;
 699         }
 700         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 701         if (err)
 702                 goto out;
 703
 704         err = nilfs_store_magic(sb, sbp);
 705         if (err)
 706                 goto failed_sbh;
 707
 708         err = nilfs_check_feature_compatibility(sb, sbp);
 709         if (err)
 710                 goto failed_sbh;
 711
 712         err = nilfs_get_blocksize(sb, sbp, &blocksize);
 713         if (err)
 714                 goto failed_sbh;
 715
 716         if (blocksize < NILFS_MIN_BLOCK_SIZE) {
 717                 nilfs_err(sb,
 718                           "couldn't mount because of unsupported filesystem blocksize %d",
 719                           blocksize);
 720                 err = -EINVAL;
 721                 goto failed_sbh;
 722         }
 723         if (sb->s_blocksize != blocksize) {
 724                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 725
 726                 if (blocksize < hw_blocksize) {
 727                         nilfs_err(sb,
 728                                   "blocksize %d too small for device (sector-size = %d)",
 729                                   blocksize, hw_blocksize);
 730                         err = -EINVAL;
 731                         goto failed_sbh;
 732                 }
 733                 nilfs_release_super_block(nilfs);
 734                 if (!sb_set_blocksize(sb, blocksize)) {
 735                         nilfs_err(sb, "bad blocksize %d", blocksize);
 736                         err = -EINVAL;
 737                         goto out;
 738                 }
 739
 740                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 741                 if (err)
 742                         goto out;
 743                         /*
 744                          * Not to failed_sbh; sbh is released automatically
 745                          * when reloading fails.
 746                          */
 747         }
 748         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 749         nilfs->ns_blocksize = blocksize;
 750
 751         get_random_bytes(&nilfs->ns_next_generation,
 752                          sizeof(nilfs->ns_next_generation));
 753
 754         err = nilfs_store_disk_layout(nilfs, sbp);
 755         if (err)
 756                 goto failed_sbh;
 757
 758         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 759
 760         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 761
 762         err = nilfs_store_log_cursor(nilfs, sbp);
 763         if (err)
 764                 goto failed_sbh;
 765
 766         set_nilfs_init(nilfs);
 767         err = 0;
 768  out:
 769         up_write(&nilfs->ns_sem);
 770         return err;
 771
 772  failed_sbh:
 773         nilfs_release_super_block(nilfs);
 774         goto out;
 775 }
 776
 777 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 778                             size_t nsegs)
 779 {
 780         sector_t seg_start, seg_end;
 781         sector_t start = 0, nblocks = 0;
 782         unsigned int sects_per_block;
 783         __u64 *sn;
 784         int ret = 0;
 785
 786         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 787                 bdev_logical_block_size(nilfs->ns_bdev);
 788         for (sn = segnump; sn < segnump + nsegs; sn++) {
 789                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 790
 791                 if (!nblocks) {
 792                         start = seg_start;
 793                         nblocks = seg_end - seg_start + 1;
 794                 } else if (start + nblocks == seg_start) {
 795                         nblocks += seg_end - seg_start + 1;
 796                 } else {
 797                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 798                                                    start * sects_per_block,
 799                                                    nblocks * sects_per_block,
 800                                                    GFP_NOFS);
 801                         if (ret < 0)
 802                                 return ret;
 803                         nblocks = 0;
 804                 }
 805         }
 806         if (nblocks)
 807                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 808                                            start * sects_per_block,
 809                                            nblocks * sects_per_block,
 810                                            GFP_NOFS);
 811         return ret;
 812 }
 813
 814 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 815 {
 816         unsigned long ncleansegs;
 817
 818         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 819         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 820         return 0;
 821 }
 822
 823 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 824 {
 825         unsigned long ncleansegs, nincsegs;
 826
 827         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 828         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 829                 nilfs->ns_blocks_per_segment + 1;
 830
 831         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 832 }
 833
 834 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 835 {
 836         struct rb_node *n;
 837         struct nilfs_root *root;
 838
 839         spin_lock(&nilfs->ns_cptree_lock);
 840         n = nilfs->ns_cptree.rb_node;
 841         while (n) {
 842                 root = rb_entry(n, struct nilfs_root, rb_node);
 843
 844                 if (cno < root->cno) {
 845                         n = n->rb_left;
 846                 } else if (cno > root->cno) {
 847                         n = n->rb_right;
 848                 } else {
 849                         refcount_inc(&root->count);
 850                         spin_unlock(&nilfs->ns_cptree_lock);
 851                         return root;
 852                 }
 853         }
 854         spin_unlock(&nilfs->ns_cptree_lock);
 855
 856         return NULL;
 857 }
 858
 859 struct nilfs_root *
 860 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 861 {
 862         struct rb_node **p, *parent;
 863         struct nilfs_root *root, *new;
 864         int err;
 865
 866         root = nilfs_lookup_root(nilfs, cno);
 867         if (root)
 868                 return root;
 869
 870         new = kzalloc(sizeof(*root), GFP_KERNEL);
 871         if (!new)
 872                 return NULL;
 873
 874         spin_lock(&nilfs->ns_cptree_lock);
 875
 876         p = &nilfs->ns_cptree.rb_node;
 877         parent = NULL;
 878
 879         while (*p) {
 880                 parent = *p;
 881                 root = rb_entry(parent, struct nilfs_root, rb_node);
 882
 883                 if (cno < root->cno) {
 884                         p = &(*p)->rb_left;
 885                 } else if (cno > root->cno) {
 886                         p = &(*p)->rb_right;
 887                 } else {
 888                         refcount_inc(&root->count);
 889                         spin_unlock(&nilfs->ns_cptree_lock);
 890                         kfree(new);
 891                         return root;
 892                 }
 893         }
 894
 895         new->cno = cno;
 896         new->ifile = NULL;
 897         new->nilfs = nilfs;
 898         refcount_set(&new->count, 1);
 899         atomic64_set(&new->inodes_count, 0);
 900         atomic64_set(&new->blocks_count, 0);
 901
 902         rb_link_node(&new->rb_node, parent, p);
 903         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 904
 905         spin_unlock(&nilfs->ns_cptree_lock);
 906
 907         err = nilfs_sysfs_create_snapshot_group(new);
 908         if (err) {
 909                 kfree(new);
 910                 new = NULL;
 911         }
 912
 913         return new;
 914 }
 915
 916 void nilfs_put_root(struct nilfs_root *root)
 917 {
 918         struct the_nilfs *nilfs = root->nilfs;
 919
 920         if (refcount_dec_and_lock(&root->count, &nilfs->ns_cptree_lock)) {
 921                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 922                 spin_unlock(&nilfs->ns_cptree_lock);
 923
 924                 nilfs_sysfs_delete_snapshot_group(root);
 925                 iput(root->ifile);
 926
 927                 kfree(root);
 928         }
 929 }