fs/nilfs2/the_nilfs.c

   1 /*
   2  * the_nilfs.c - the_nilfs shared structure.
   3  *
   4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
  21  *
  22  */
  23
  24 #include <linux/buffer_head.h>
  25 #include <linux/slab.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/crc32.h>
  29 #include "nilfs.h"
  30 #include "segment.h"
  31 #include "alloc.h"
  32 #include "cpfile.h"
  33 #include "sufile.h"
  34 #include "dat.h"
  35 #include "segbuf.h"
  36
  37
  38 static int nilfs_valid_sb(struct nilfs_super_block *sbp);
  39
  40 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  41                             sector_t start_blocknr, u64 seq, __u64 cno)
  42 {
  43         spin_lock(&nilfs->ns_last_segment_lock);
  44         nilfs->ns_last_pseg = start_blocknr;
  45         nilfs->ns_last_seq = seq;
  46         nilfs->ns_last_cno = cno;
  47
  48         if (!nilfs_sb_dirty(nilfs)) {
  49                 if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
  50                         goto stay_cursor;
  51
  52                 set_nilfs_sb_dirty(nilfs);
  53         }
  54         nilfs->ns_prev_seq = nilfs->ns_last_seq;
  55
  56  stay_cursor:
  57         spin_unlock(&nilfs->ns_last_segment_lock);
  58 }
  59
  60 /**
  61  * alloc_nilfs - allocate a nilfs object
  62  * @bdev: block device to which the_nilfs is related
  63  *
  64  * Return Value: On success, pointer to the_nilfs is returned.
  65  * On error, NULL is returned.
  66  */
  67 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  68 {
  69         struct the_nilfs *nilfs;
  70
  71         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  72         if (!nilfs)
  73                 return NULL;
  74
  75         nilfs->ns_bdev = bdev;
  76         atomic_set(&nilfs->ns_ndirtyblks, 0);
  77         init_rwsem(&nilfs->ns_sem);
  78         init_rwsem(&nilfs->ns_writer_sem);
  79         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
  80         spin_lock_init(&nilfs->ns_last_segment_lock);
  81         nilfs->ns_cptree = RB_ROOT;
  82         spin_lock_init(&nilfs->ns_cptree_lock);
  83         init_rwsem(&nilfs->ns_segctor_sem);
  84
  85         return nilfs;
  86 }
  87
  88 /**
  89  * destroy_nilfs - destroy nilfs object
  90  * @nilfs: nilfs object to be released
  91  */
  92 void destroy_nilfs(struct the_nilfs *nilfs)
  93 {
  94         might_sleep();
  95         if (nilfs_loaded(nilfs)) {
  96                 nilfs_mdt_destroy(nilfs->ns_sufile);
  97                 nilfs_mdt_destroy(nilfs->ns_cpfile);
  98                 nilfs_mdt_destroy(nilfs->ns_dat);
  99         }
 100         if (nilfs_init(nilfs)) {
 101                 brelse(nilfs->ns_sbh[0]);
 102                 brelse(nilfs->ns_sbh[1]);
 103         }
 104         kfree(nilfs);
 105 }
 106
 107 static int nilfs_load_super_root(struct the_nilfs *nilfs, sector_t sr_block)
 108 {
 109         struct buffer_head *bh_sr;
 110         struct nilfs_super_root *raw_sr;
 111         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 112         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 113         unsigned inode_size;
 114         int err;
 115
 116         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
 117         if (unlikely(err))
 118                 return err;
 119
 120         down_read(&nilfs->ns_sem);
 121         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 122         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 123         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 124         up_read(&nilfs->ns_sem);
 125
 126         inode_size = nilfs->ns_inode_size;
 127
 128         err = -ENOMEM;
 129         nilfs->ns_dat = nilfs_dat_new(nilfs, dat_entry_size);
 130         if (unlikely(!nilfs->ns_dat))
 131                 goto failed;
 132
 133         nilfs->ns_cpfile = nilfs_cpfile_new(nilfs, checkpoint_size);
 134         if (unlikely(!nilfs->ns_cpfile))
 135                 goto failed_dat;
 136
 137         nilfs->ns_sufile = nilfs_sufile_new(nilfs, segment_usage_size);
 138         if (unlikely(!nilfs->ns_sufile))
 139                 goto failed_cpfile;
 140
 141         err = nilfs_dat_read(nilfs->ns_dat, (void *)bh_sr->b_data +
 142                              NILFS_SR_DAT_OFFSET(inode_size));
 143         if (unlikely(err))
 144                 goto failed_sufile;
 145
 146         err = nilfs_cpfile_read(nilfs->ns_cpfile, (void *)bh_sr->b_data +
 147                                 NILFS_SR_CPFILE_OFFSET(inode_size));
 148         if (unlikely(err))
 149                 goto failed_sufile;
 150
 151         err = nilfs_sufile_read(nilfs->ns_sufile, (void *)bh_sr->b_data +
 152                                 NILFS_SR_SUFILE_OFFSET(inode_size));
 153         if (unlikely(err))
 154                 goto failed_sufile;
 155
 156         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 157         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 158
 159  failed:
 160         brelse(bh_sr);
 161         return err;
 162
 163  failed_sufile:
 164         nilfs_mdt_destroy(nilfs->ns_sufile);
 165
 166  failed_cpfile:
 167         nilfs_mdt_destroy(nilfs->ns_cpfile);
 168
 169  failed_dat:
 170         nilfs_mdt_destroy(nilfs->ns_dat);
 171         goto failed;
 172 }
 173
 174 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 175 {
 176         memset(ri, 0, sizeof(*ri));
 177         INIT_LIST_HEAD(&ri->ri_used_segments);
 178 }
 179
 180 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 181 {
 182         nilfs_dispose_segment_list(&ri->ri_used_segments);
 183 }
 184
 185 /**
 186  * nilfs_store_log_cursor - load log cursor from a super block
 187  * @nilfs: nilfs object
 188  * @sbp: buffer storing super block to be read
 189  *
 190  * nilfs_store_log_cursor() reads the last position of the log
 191  * containing a super root from a given super block, and initializes
 192  * relevant information on the nilfs object preparatory for log
 193  * scanning and recovery.
 194  */
 195 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
 196                                   struct nilfs_super_block *sbp)
 197 {
 198         int ret = 0;
 199
 200         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 201         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 202         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 203
 204         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 205         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 206         nilfs->ns_segnum =
 207                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 208         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 209         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 210                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 211                 ret = -EINVAL;
 212         }
 213         return ret;
 214 }
 215
 216 /**
 217  * load_nilfs - load and recover the nilfs
 218  * @nilfs: the_nilfs structure to be released
 219  * @sbi: nilfs_sb_info used to recover past segment
 220  *
 221  * load_nilfs() searches and load the latest super root,
 222  * attaches the last segment, and does recovery if needed.
 223  * The caller must call this exclusively for simultaneous mounts.
 224  */
 225 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 226 {
 227         struct nilfs_recovery_info ri;
 228         unsigned int s_flags = sbi->s_super->s_flags;
 229         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 230         int valid_fs = nilfs_valid_fs(nilfs);
 231         int err;
 232
 233         if (!valid_fs) {
 234                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
 235                 if (s_flags & MS_RDONLY) {
 236                         printk(KERN_INFO "NILFS: INFO: recovery "
 237                                "required for readonly filesystem.\n");
 238                         printk(KERN_INFO "NILFS: write access will "
 239                                "be enabled during recovery.\n");
 240                 }
 241         }
 242
 243         nilfs_init_recovery_info(&ri);
 244
 245         err = nilfs_search_super_root(nilfs, &ri);
 246         if (unlikely(err)) {
 247                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 248                 int blocksize;
 249
 250                 if (err != -EINVAL)
 251                         goto scan_error;
 252
 253                 if (!nilfs_valid_sb(sbp[1])) {
 254                         printk(KERN_WARNING
 255                                "NILFS warning: unable to fall back to spare"
 256                                "super block\n");
 257                         goto scan_error;
 258                 }
 259                 printk(KERN_INFO
 260                        "NILFS: try rollback from an earlier position\n");
 261
 262                 /*
 263                  * restore super block with its spare and reconfigure
 264                  * relevant states of the nilfs object.
 265                  */
 266                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 267                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 268                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 269
 270                 /* verify consistency between two super blocks */
 271                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
 272                 if (blocksize != nilfs->ns_blocksize) {
 273                         printk(KERN_WARNING
 274                                "NILFS warning: blocksize differs between "
 275                                "two super blocks (%d != %d)\n",
 276                                blocksize, nilfs->ns_blocksize);
 277                         goto scan_error;
 278                 }
 279
 280                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 281                 if (err)
 282                         goto scan_error;
 283
 284                 /* drop clean flag to allow roll-forward and recovery */
 285                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 286                 valid_fs = 0;
 287
 288                 err = nilfs_search_super_root(nilfs, &ri);
 289                 if (err)
 290                         goto scan_error;
 291         }
 292
 293         err = nilfs_load_super_root(nilfs, ri.ri_super_root);
 294         if (unlikely(err)) {
 295                 printk(KERN_ERR "NILFS: error loading super root.\n");
 296                 goto failed;
 297         }
 298
 299         if (valid_fs)
 300                 goto skip_recovery;
 301
 302         if (s_flags & MS_RDONLY) {
 303                 __u64 features;
 304
 305                 if (nilfs_test_opt(sbi, NORECOVERY)) {
 306                         printk(KERN_INFO "NILFS: norecovery option specified. "
 307                                "skipping roll-forward recovery\n");
 308                         goto skip_recovery;
 309                 }
 310                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 311                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 312                 if (features) {
 313                         printk(KERN_ERR "NILFS: couldn't proceed with "
 314                                "recovery because of unsupported optional "
 315                                "features (%llx)\n",
 316                                (unsigned long long)features);
 317                         err = -EROFS;
 318                         goto failed_unload;
 319                 }
 320                 if (really_read_only) {
 321                         printk(KERN_ERR "NILFS: write access "
 322                                "unavailable, cannot proceed.\n");
 323                         err = -EROFS;
 324                         goto failed_unload;
 325                 }
 326                 sbi->s_super->s_flags &= ~MS_RDONLY;
 327         } else if (nilfs_test_opt(sbi, NORECOVERY)) {
 328                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
 329                        "option was specified for a read/write mount\n");
 330                 err = -EINVAL;
 331                 goto failed_unload;
 332         }
 333
 334         err = nilfs_salvage_orphan_logs(nilfs, sbi, &ri);
 335         if (err)
 336                 goto failed_unload;
 337
 338         down_write(&nilfs->ns_sem);
 339         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 340         err = nilfs_cleanup_super(sbi);
 341         up_write(&nilfs->ns_sem);
 342
 343         if (err) {
 344                 printk(KERN_ERR "NILFS: failed to update super block. "
 345                        "recovery unfinished.\n");
 346                 goto failed_unload;
 347         }
 348         printk(KERN_INFO "NILFS: recovery complete.\n");
 349
 350  skip_recovery:
 351         set_nilfs_loaded(nilfs);
 352         nilfs_clear_recovery_info(&ri);
 353         sbi->s_super->s_flags = s_flags;
 354         return 0;
 355
 356  scan_error:
 357         printk(KERN_ERR "NILFS: error searching super root.\n");
 358         goto failed;
 359
 360  failed_unload:
 361         nilfs_mdt_destroy(nilfs->ns_cpfile);
 362         nilfs_mdt_destroy(nilfs->ns_sufile);
 363         nilfs_mdt_destroy(nilfs->ns_dat);
 364
 365  failed:
 366         nilfs_clear_recovery_info(&ri);
 367         sbi->s_super->s_flags = s_flags;
 368         return err;
 369 }
 370
 371 static unsigned long long nilfs_max_size(unsigned int blkbits)
 372 {
 373         unsigned int max_bits;
 374         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 375
 376         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 377         if (max_bits < 64)
 378                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 379         return res;
 380 }
 381
 382 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 383                                    struct nilfs_super_block *sbp)
 384 {
 385         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 386                 printk(KERN_ERR "NILFS: unsupported revision "
 387                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 388                        "Please check the version of mkfs.nilfs.\n",
 389                        le32_to_cpu(sbp->s_rev_level),
 390                        le16_to_cpu(sbp->s_minor_rev_level),
 391                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 392                 return -EINVAL;
 393         }
 394         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 395         if (nilfs->ns_sbsize > BLOCK_SIZE)
 396                 return -EINVAL;
 397
 398         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 399         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 400
 401         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 402         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 403                 printk(KERN_ERR "NILFS: too short segment.\n");
 404                 return -EINVAL;
 405         }
 406
 407         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 408         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 409         nilfs->ns_r_segments_percentage =
 410                 le32_to_cpu(sbp->s_r_segments_percentage);
 411         nilfs->ns_nrsvsegs =
 412                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 413                       DIV_ROUND_UP(nilfs->ns_nsegments *
 414                                    nilfs->ns_r_segments_percentage, 100));
 415         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 416         return 0;
 417 }
 418
 419 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 420 {
 421         static unsigned char sum[4];
 422         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 423         size_t bytes;
 424         u32 crc;
 425
 426         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 427                 return 0;
 428         bytes = le16_to_cpu(sbp->s_bytes);
 429         if (bytes > BLOCK_SIZE)
 430                 return 0;
 431         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 432                        sumoff);
 433         crc = crc32_le(crc, sum, 4);
 434         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 435                        bytes - sumoff - 4);
 436         return crc == le32_to_cpu(sbp->s_sum);
 437 }
 438
 439 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 440 {
 441         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 442                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 443                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 444 }
 445
 446 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 447 {
 448         int i;
 449
 450         for (i = 0; i < 2; i++) {
 451                 if (nilfs->ns_sbp[i]) {
 452                         brelse(nilfs->ns_sbh[i]);
 453                         nilfs->ns_sbh[i] = NULL;
 454                         nilfs->ns_sbp[i] = NULL;
 455                 }
 456         }
 457 }
 458
 459 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 460 {
 461         brelse(nilfs->ns_sbh[0]);
 462         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 463         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 464         nilfs->ns_sbh[1] = NULL;
 465         nilfs->ns_sbp[1] = NULL;
 466 }
 467
 468 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 469 {
 470         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 471         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 472
 473         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 474         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 475         nilfs->ns_sbh[1] = tsbh;
 476         nilfs->ns_sbp[1] = tsbp;
 477 }
 478
 479 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 480                                   struct super_block *sb, int blocksize,
 481                                   struct nilfs_super_block **sbpp)
 482 {
 483         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 484         struct buffer_head **sbh = nilfs->ns_sbh;
 485         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 486         int valid[2], swp = 0;
 487
 488         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 489                                         &sbh[0]);
 490         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 491
 492         if (!sbp[0]) {
 493                 if (!sbp[1]) {
 494                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 495                         return -EIO;
 496                 }
 497                 printk(KERN_WARNING
 498                        "NILFS warning: unable to read primary superblock\n");
 499         } else if (!sbp[1])
 500                 printk(KERN_WARNING
 501                        "NILFS warning: unable to read secondary superblock\n");
 502
 503         /*
 504          * Compare two super blocks and set 1 in swp if the secondary
 505          * super block is valid and newer.  Otherwise, set 0 in swp.
 506          */
 507         valid[0] = nilfs_valid_sb(sbp[0]);
 508         valid[1] = nilfs_valid_sb(sbp[1]);
 509         swp = valid[1] && (!valid[0] ||
 510                            le64_to_cpu(sbp[1]->s_last_cno) >
 511                            le64_to_cpu(sbp[0]->s_last_cno));
 512
 513         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 514                 brelse(sbh[1]);
 515                 sbh[1] = NULL;
 516                 sbp[1] = NULL;
 517                 swp = 0;
 518         }
 519         if (!valid[swp]) {
 520                 nilfs_release_super_block(nilfs);
 521                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 522                        sb->s_id);
 523                 return -EINVAL;
 524         }
 525
 526         if (!valid[!swp])
 527                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 528                        "using spare superblock.\n");
 529         if (swp)
 530                 nilfs_swap_super_block(nilfs);
 531
 532         nilfs->ns_sbwcount = 0;
 533         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 534         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 535         *sbpp = sbp[0];
 536         return 0;
 537 }
 538
 539 /**
 540  * init_nilfs - initialize a NILFS instance.
 541  * @nilfs: the_nilfs structure
 542  * @sbi: nilfs_sb_info
 543  * @sb: super block
 544  * @data: mount options
 545  *
 546  * init_nilfs() performs common initialization per block device (e.g.
 547  * reading the super block, getting disk layout information, initializing
 548  * shared fields in the_nilfs).
 549  *
 550  * Return Value: On success, 0 is returned. On error, a negative error
 551  * code is returned.
 552  */
 553 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 554 {
 555         struct super_block *sb = sbi->s_super;
 556         struct nilfs_super_block *sbp;
 557         struct backing_dev_info *bdi;
 558         int blocksize;
 559         int err;
 560
 561         down_write(&nilfs->ns_sem);
 562
 563         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 564         if (!blocksize) {
 565                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 566                 err = -EINVAL;
 567                 goto out;
 568         }
 569         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 570         if (err)
 571                 goto out;
 572
 573         err = nilfs_store_magic_and_option(sb, sbp, data);
 574         if (err)
 575                 goto failed_sbh;
 576
 577         err = nilfs_check_feature_compatibility(sb, sbp);
 578         if (err)
 579                 goto failed_sbh;
 580
 581         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 582         if (blocksize < NILFS_MIN_BLOCK_SIZE ||
 583             blocksize > NILFS_MAX_BLOCK_SIZE) {
 584                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
 585                        "filesystem blocksize %d\n", blocksize);
 586                 err = -EINVAL;
 587                 goto failed_sbh;
 588         }
 589         if (sb->s_blocksize != blocksize) {
 590                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 591
 592                 if (blocksize < hw_blocksize) {
 593                         printk(KERN_ERR
 594                                "NILFS: blocksize %d too small for device "
 595                                "(sector-size = %d).\n",
 596                                blocksize, hw_blocksize);
 597                         err = -EINVAL;
 598                         goto failed_sbh;
 599                 }
 600                 nilfs_release_super_block(nilfs);
 601                 sb_set_blocksize(sb, blocksize);
 602
 603                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 604                 if (err)
 605                         goto out;
 606                         /* not failed_sbh; sbh is released automatically
 607                            when reloading fails. */
 608         }
 609         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 610         nilfs->ns_blocksize = blocksize;
 611
 612         err = nilfs_store_disk_layout(nilfs, sbp);
 613         if (err)
 614                 goto failed_sbh;
 615
 616         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 617
 618         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 619
 620         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 621         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 622
 623         err = nilfs_store_log_cursor(nilfs, sbp);
 624         if (err)
 625                 goto failed_sbh;
 626
 627         set_nilfs_init(nilfs);
 628         err = 0;
 629  out:
 630         up_write(&nilfs->ns_sem);
 631         return err;
 632
 633  failed_sbh:
 634         nilfs_release_super_block(nilfs);
 635         goto out;
 636 }
 637
 638 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 639                             size_t nsegs)
 640 {
 641         sector_t seg_start, seg_end;
 642         sector_t start = 0, nblocks = 0;
 643         unsigned int sects_per_block;
 644         __u64 *sn;
 645         int ret = 0;
 646
 647         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 648                 bdev_logical_block_size(nilfs->ns_bdev);
 649         for (sn = segnump; sn < segnump + nsegs; sn++) {
 650                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 651
 652                 if (!nblocks) {
 653                         start = seg_start;
 654                         nblocks = seg_end - seg_start + 1;
 655                 } else if (start + nblocks == seg_start) {
 656                         nblocks += seg_end - seg_start + 1;
 657                 } else {
 658                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 659                                                    start * sects_per_block,
 660                                                    nblocks * sects_per_block,
 661                                                    GFP_NOFS,
 662                                                    BLKDEV_IFL_WAIT |
 663                                                    BLKDEV_IFL_BARRIER);
 664                         if (ret < 0)
 665                                 return ret;
 666                         nblocks = 0;
 667                 }
 668         }
 669         if (nblocks)
 670                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 671                                            start * sects_per_block,
 672                                            nblocks * sects_per_block,
 673                                            GFP_NOFS,
 674                                           BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 675         return ret;
 676 }
 677
 678 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 679 {
 680         struct inode *dat = nilfs_dat_inode(nilfs);
 681         unsigned long ncleansegs;
 682
 683         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 684         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 685         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 686         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 687         return 0;
 688 }
 689
 690 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 691 {
 692         unsigned long ncleansegs, nincsegs;
 693
 694         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 695         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 696                 nilfs->ns_blocks_per_segment + 1;
 697
 698         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 699 }
 700
 701 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 702 {
 703         struct rb_node *n;
 704         struct nilfs_root *root;
 705
 706         spin_lock(&nilfs->ns_cptree_lock);
 707         n = nilfs->ns_cptree.rb_node;
 708         while (n) {
 709                 root = rb_entry(n, struct nilfs_root, rb_node);
 710
 711                 if (cno < root->cno) {
 712                         n = n->rb_left;
 713                 } else if (cno > root->cno) {
 714                         n = n->rb_right;
 715                 } else {
 716                         atomic_inc(&root->count);
 717                         spin_unlock(&nilfs->ns_cptree_lock);
 718                         return root;
 719                 }
 720         }
 721         spin_unlock(&nilfs->ns_cptree_lock);
 722
 723         return NULL;
 724 }
 725
 726 struct nilfs_root *
 727 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 728 {
 729         struct rb_node **p, *parent;
 730         struct nilfs_root *root, *new;
 731
 732         root = nilfs_lookup_root(nilfs, cno);
 733         if (root)
 734                 return root;
 735
 736         new = kmalloc(sizeof(*root), GFP_KERNEL);
 737         if (!new)
 738                 return NULL;
 739
 740         spin_lock(&nilfs->ns_cptree_lock);
 741
 742         p = &nilfs->ns_cptree.rb_node;
 743         parent = NULL;
 744
 745         while (*p) {
 746                 parent = *p;
 747                 root = rb_entry(parent, struct nilfs_root, rb_node);
 748
 749                 if (cno < root->cno) {
 750                         p = &(*p)->rb_left;
 751                 } else if (cno > root->cno) {
 752                         p = &(*p)->rb_right;
 753                 } else {
 754                         atomic_inc(&root->count);
 755                         spin_unlock(&nilfs->ns_cptree_lock);
 756                         kfree(new);
 757                         return root;
 758                 }
 759         }
 760
 761         new->cno = cno;
 762         new->ifile = NULL;
 763         new->nilfs = nilfs;
 764         atomic_set(&new->count, 1);
 765         atomic_set(&new->inodes_count, 0);
 766         atomic_set(&new->blocks_count, 0);
 767
 768         rb_link_node(&new->rb_node, parent, p);
 769         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 770
 771         spin_unlock(&nilfs->ns_cptree_lock);
 772
 773         return new;
 774 }
 775
 776 void nilfs_put_root(struct nilfs_root *root)
 777 {
 778         if (atomic_dec_and_test(&root->count)) {
 779                 struct the_nilfs *nilfs = root->nilfs;
 780
 781                 spin_lock(&nilfs->ns_cptree_lock);
 782                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 783                 spin_unlock(&nilfs->ns_cptree_lock);
 784                 if (root->ifile)
 785                         nilfs_mdt_destroy(root->ifile);
 786
 787                 kfree(root);
 788         }
 789 }
 790
 791 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 792                                 int snapshot_mount)
 793 {
 794         struct nilfs_root *root;
 795         int ret;
 796
 797         if (cno < 0 || cno > nilfs->ns_cno)
 798                 return false;
 799
 800         if (cno >= nilfs_last_cno(nilfs))
 801                 return true;    /* protect recent checkpoints */
 802
 803         ret = false;
 804         root = nilfs_lookup_root(nilfs, cno);
 805         if (root) {
 806                 ret = true;
 807                 nilfs_put_root(root);
 808         }
 809         return ret;
 810 }