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 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
 409 {
 410         nilfs->ns_nsegments = nsegs;
 411         nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
 412 }
 413
 414 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 415                                    struct nilfs_super_block *sbp)
 416 {
 417         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 418                 nilfs_err(nilfs->ns_sb,
 419                           "unsupported revision (superblock rev.=%d.%d, current rev.=%d.%d). Please check the version of mkfs.nilfs(2).",
 420                           le32_to_cpu(sbp->s_rev_level),
 421                           le16_to_cpu(sbp->s_minor_rev_level),
 422                           NILFS_CURRENT_REV, NILFS_MINOR_REV);
 423                 return -EINVAL;
 424         }
 425         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 426         if (nilfs->ns_sbsize > BLOCK_SIZE)
 427                 return -EINVAL;
 428
 429         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 430         if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
 431                 nilfs_err(nilfs->ns_sb, "too large inode size: %d bytes",
 432                           nilfs->ns_inode_size);
 433                 return -EINVAL;
 434         } else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
 435                 nilfs_err(nilfs->ns_sb, "too small inode size: %d bytes",
 436                           nilfs->ns_inode_size);
 437                 return -EINVAL;
 438         }
 439
 440         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 441
 442         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 443         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 444                 nilfs_err(nilfs->ns_sb, "too short segment: %lu blocks",
 445                           nilfs->ns_blocks_per_segment);
 446                 return -EINVAL;
 447         }
 448
 449         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 450         nilfs->ns_r_segments_percentage =
 451                 le32_to_cpu(sbp->s_r_segments_percentage);
 452         if (nilfs->ns_r_segments_percentage < 1 ||
 453             nilfs->ns_r_segments_percentage > 99) {
 454                 nilfs_err(nilfs->ns_sb,
 455                           "invalid reserved segments percentage: %lu",
 456                           nilfs->ns_r_segments_percentage);
 457                 return -EINVAL;
 458         }
 459
 460         nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments));
 461         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 462         return 0;
 463 }
 464
 465 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 466 {
 467         static unsigned char sum[4];
 468         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 469         size_t bytes;
 470         u32 crc;
 471
 472         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 473                 return 0;
 474         bytes = le16_to_cpu(sbp->s_bytes);
 475         if (bytes < sumoff + 4 || bytes > BLOCK_SIZE)
 476                 return 0;
 477         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 478                        sumoff);
 479         crc = crc32_le(crc, sum, 4);
 480         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 481                        bytes - sumoff - 4);
 482         return crc == le32_to_cpu(sbp->s_sum);
 483 }
 484
 485 /**
 486  * nilfs_sb2_bad_offset - check the location of the second superblock
 487  * @sbp: superblock raw data buffer
 488  * @offset: byte offset of second superblock calculated from device size
 489  *
 490  * nilfs_sb2_bad_offset() checks if the position on the second
 491  * superblock is valid or not based on the filesystem parameters
 492  * stored in @sbp.  If @offset points to a location within the segment
 493  * area, or if the parameters themselves are not normal, it is
 494  * determined to be invalid.
 495  *
 496  * Return Value: true if invalid, false if valid.
 497  */
 498 static bool nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 499 {
 500         unsigned int shift_bits = le32_to_cpu(sbp->s_log_block_size);
 501         u32 blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 502         u64 nsegments = le64_to_cpu(sbp->s_nsegments);
 503         u64 index;
 504
 505         if (blocks_per_segment < NILFS_SEG_MIN_BLOCKS ||
 506             shift_bits > ilog2(NILFS_MAX_BLOCK_SIZE) - BLOCK_SIZE_BITS)
 507                 return true;
 508
 509         index = offset >> (shift_bits + BLOCK_SIZE_BITS);
 510         do_div(index, blocks_per_segment);
 511         return index < nsegments;
 512 }
 513
 514 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 515 {
 516         int i;
 517
 518         for (i = 0; i < 2; i++) {
 519                 if (nilfs->ns_sbp[i]) {
 520                         brelse(nilfs->ns_sbh[i]);
 521                         nilfs->ns_sbh[i] = NULL;
 522                         nilfs->ns_sbp[i] = NULL;
 523                 }
 524         }
 525 }
 526
 527 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 528 {
 529         brelse(nilfs->ns_sbh[0]);
 530         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 531         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 532         nilfs->ns_sbh[1] = NULL;
 533         nilfs->ns_sbp[1] = NULL;
 534 }
 535
 536 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 537 {
 538         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 539         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 540
 541         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 542         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 543         nilfs->ns_sbh[1] = tsbh;
 544         nilfs->ns_sbp[1] = tsbp;
 545 }
 546
 547 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 548                                   struct super_block *sb, int blocksize,
 549                                   struct nilfs_super_block **sbpp)
 550 {
 551         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 552         struct buffer_head **sbh = nilfs->ns_sbh;
 553         u64 sb2off, devsize = bdev_nr_bytes(nilfs->ns_bdev);
 554         int valid[2], swp = 0;
 555
 556         if (devsize < NILFS_SEG_MIN_BLOCKS * NILFS_MIN_BLOCK_SIZE + 4096) {
 557                 nilfs_err(sb, "device size too small");
 558                 return -EINVAL;
 559         }
 560         sb2off = NILFS_SB2_OFFSET_BYTES(devsize);
 561
 562         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 563                                         &sbh[0]);
 564         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 565
 566         if (!sbp[0]) {
 567                 if (!sbp[1]) {
 568                         nilfs_err(sb, "unable to read superblock");
 569                         return -EIO;
 570                 }
 571                 nilfs_warn(sb,
 572                            "unable to read primary superblock (blocksize = %d)",
 573                            blocksize);
 574         } else if (!sbp[1]) {
 575                 nilfs_warn(sb,
 576                            "unable to read secondary superblock (blocksize = %d)",
 577                            blocksize);
 578         }
 579
 580         /*
 581          * Compare two super blocks and set 1 in swp if the secondary
 582          * super block is valid and newer.  Otherwise, set 0 in swp.
 583          */
 584         valid[0] = nilfs_valid_sb(sbp[0]);
 585         valid[1] = nilfs_valid_sb(sbp[1]);
 586         swp = valid[1] && (!valid[0] ||
 587                            le64_to_cpu(sbp[1]->s_last_cno) >
 588                            le64_to_cpu(sbp[0]->s_last_cno));
 589
 590         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 591                 brelse(sbh[1]);
 592                 sbh[1] = NULL;
 593                 sbp[1] = NULL;
 594                 valid[1] = 0;
 595                 swp = 0;
 596         }
 597         if (!valid[swp]) {
 598                 nilfs_release_super_block(nilfs);
 599                 nilfs_err(sb, "couldn't find nilfs on the device");
 600                 return -EINVAL;
 601         }
 602
 603         if (!valid[!swp])
 604                 nilfs_warn(sb,
 605                            "broken superblock, retrying with spare superblock (blocksize = %d)",
 606                            blocksize);
 607         if (swp)
 608                 nilfs_swap_super_block(nilfs);
 609
 610         nilfs->ns_sbwcount = 0;
 611         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 612         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 613         *sbpp = sbp[0];
 614         return 0;
 615 }
 616
 617 /**
 618  * init_nilfs - initialize a NILFS instance.
 619  * @nilfs: the_nilfs structure
 620  * @sb: super block
 621  * @data: mount options
 622  *
 623  * init_nilfs() performs common initialization per block device (e.g.
 624  * reading the super block, getting disk layout information, initializing
 625  * shared fields in the_nilfs).
 626  *
 627  * Return Value: On success, 0 is returned. On error, a negative error
 628  * code is returned.
 629  */
 630 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data)
 631 {
 632         struct nilfs_super_block *sbp;
 633         int blocksize;
 634         int err;
 635
 636         down_write(&nilfs->ns_sem);
 637
 638         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 639         if (!blocksize) {
 640                 nilfs_err(sb, "unable to set blocksize");
 641                 err = -EINVAL;
 642                 goto out;
 643         }
 644         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 645         if (err)
 646                 goto out;
 647
 648         err = nilfs_store_magic_and_option(sb, sbp, data);
 649         if (err)
 650                 goto failed_sbh;
 651
 652         err = nilfs_check_feature_compatibility(sb, sbp);
 653         if (err)
 654                 goto failed_sbh;
 655
 656         err = nilfs_get_blocksize(sb, sbp, &blocksize);
 657         if (err)
 658                 goto failed_sbh;
 659
 660         if (blocksize < NILFS_MIN_BLOCK_SIZE) {
 661                 nilfs_err(sb,
 662                           "couldn't mount because of unsupported filesystem blocksize %d",
 663                           blocksize);
 664                 err = -EINVAL;
 665                 goto failed_sbh;
 666         }
 667         if (sb->s_blocksize != blocksize) {
 668                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 669
 670                 if (blocksize < hw_blocksize) {
 671                         nilfs_err(sb,
 672                                   "blocksize %d too small for device (sector-size = %d)",
 673                                   blocksize, hw_blocksize);
 674                         err = -EINVAL;
 675                         goto failed_sbh;
 676                 }
 677                 nilfs_release_super_block(nilfs);
 678                 sb_set_blocksize(sb, blocksize);
 679
 680                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 681                 if (err)
 682                         goto out;
 683                         /*
 684                          * Not to failed_sbh; sbh is released automatically
 685                          * when reloading fails.
 686                          */
 687         }
 688         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 689         nilfs->ns_blocksize = blocksize;
 690
 691         get_random_bytes(&nilfs->ns_next_generation,
 692                          sizeof(nilfs->ns_next_generation));
 693
 694         err = nilfs_store_disk_layout(nilfs, sbp);
 695         if (err)
 696                 goto failed_sbh;
 697
 698         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 699
 700         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 701
 702         err = nilfs_store_log_cursor(nilfs, sbp);
 703         if (err)
 704                 goto failed_sbh;
 705
 706         set_nilfs_init(nilfs);
 707         err = 0;
 708  out:
 709         up_write(&nilfs->ns_sem);
 710         return err;
 711
 712  failed_sbh:
 713         nilfs_release_super_block(nilfs);
 714         goto out;
 715 }
 716
 717 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 718                             size_t nsegs)
 719 {
 720         sector_t seg_start, seg_end;
 721         sector_t start = 0, nblocks = 0;
 722         unsigned int sects_per_block;
 723         __u64 *sn;
 724         int ret = 0;
 725
 726         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 727                 bdev_logical_block_size(nilfs->ns_bdev);
 728         for (sn = segnump; sn < segnump + nsegs; sn++) {
 729                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 730
 731                 if (!nblocks) {
 732                         start = seg_start;
 733                         nblocks = seg_end - seg_start + 1;
 734                 } else if (start + nblocks == seg_start) {
 735                         nblocks += seg_end - seg_start + 1;
 736                 } else {
 737                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 738                                                    start * sects_per_block,
 739                                                    nblocks * sects_per_block,
 740                                                    GFP_NOFS);
 741                         if (ret < 0)
 742                                 return ret;
 743                         nblocks = 0;
 744                 }
 745         }
 746         if (nblocks)
 747                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 748                                            start * sects_per_block,
 749                                            nblocks * sects_per_block,
 750                                            GFP_NOFS);
 751         return ret;
 752 }
 753
 754 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 755 {
 756         unsigned long ncleansegs;
 757
 758         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 759         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 760         return 0;
 761 }
 762
 763 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 764 {
 765         unsigned long ncleansegs, nincsegs;
 766
 767         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 768         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 769                 nilfs->ns_blocks_per_segment + 1;
 770
 771         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 772 }
 773
 774 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 775 {
 776         struct rb_node *n;
 777         struct nilfs_root *root;
 778
 779         spin_lock(&nilfs->ns_cptree_lock);
 780         n = nilfs->ns_cptree.rb_node;
 781         while (n) {
 782                 root = rb_entry(n, struct nilfs_root, rb_node);
 783
 784                 if (cno < root->cno) {
 785                         n = n->rb_left;
 786                 } else if (cno > root->cno) {
 787                         n = n->rb_right;
 788                 } else {
 789                         refcount_inc(&root->count);
 790                         spin_unlock(&nilfs->ns_cptree_lock);
 791                         return root;
 792                 }
 793         }
 794         spin_unlock(&nilfs->ns_cptree_lock);
 795
 796         return NULL;
 797 }
 798
 799 struct nilfs_root *
 800 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 801 {
 802         struct rb_node **p, *parent;
 803         struct nilfs_root *root, *new;
 804         int err;
 805
 806         root = nilfs_lookup_root(nilfs, cno);
 807         if (root)
 808                 return root;
 809
 810         new = kzalloc(sizeof(*root), GFP_KERNEL);
 811         if (!new)
 812                 return NULL;
 813
 814         spin_lock(&nilfs->ns_cptree_lock);
 815
 816         p = &nilfs->ns_cptree.rb_node;
 817         parent = NULL;
 818
 819         while (*p) {
 820                 parent = *p;
 821                 root = rb_entry(parent, struct nilfs_root, rb_node);
 822
 823                 if (cno < root->cno) {
 824                         p = &(*p)->rb_left;
 825                 } else if (cno > root->cno) {
 826                         p = &(*p)->rb_right;
 827                 } else {
 828                         refcount_inc(&root->count);
 829                         spin_unlock(&nilfs->ns_cptree_lock);
 830                         kfree(new);
 831                         return root;
 832                 }
 833         }
 834
 835         new->cno = cno;
 836         new->ifile = NULL;
 837         new->nilfs = nilfs;
 838         refcount_set(&new->count, 1);
 839         atomic64_set(&new->inodes_count, 0);
 840         atomic64_set(&new->blocks_count, 0);
 841
 842         rb_link_node(&new->rb_node, parent, p);
 843         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 844
 845         spin_unlock(&nilfs->ns_cptree_lock);
 846
 847         err = nilfs_sysfs_create_snapshot_group(new);
 848         if (err) {
 849                 kfree(new);
 850                 new = NULL;
 851         }
 852
 853         return new;
 854 }
 855
 856 void nilfs_put_root(struct nilfs_root *root)
 857 {
 858         struct the_nilfs *nilfs = root->nilfs;
 859
 860         if (refcount_dec_and_lock(&root->count, &nilfs->ns_cptree_lock)) {
 861                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 862                 spin_unlock(&nilfs->ns_cptree_lock);
 863
 864                 nilfs_sysfs_delete_snapshot_group(root);
 865                 iput(root->ifile);
 866
 867                 kfree(root);
 868         }
 869 }