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                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 100         }
 101         if (nilfs_init(nilfs)) {
 102                 brelse(nilfs->ns_sbh[0]);
 103                 brelse(nilfs->ns_sbh[1]);
 104         }
 105         kfree(nilfs);
 106 }
 107
 108 static int nilfs_load_super_root(struct the_nilfs *nilfs, sector_t sr_block)
 109 {
 110         struct buffer_head *bh_sr;
 111         struct nilfs_super_root *raw_sr;
 112         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 113         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 114         unsigned inode_size;
 115         int err;
 116
 117         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
 118         if (unlikely(err))
 119                 return err;
 120
 121         down_read(&nilfs->ns_sem);
 122         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 123         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 124         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 125         up_read(&nilfs->ns_sem);
 126
 127         inode_size = nilfs->ns_inode_size;
 128
 129         err = -ENOMEM;
 130         nilfs->ns_dat = nilfs_dat_new(nilfs, dat_entry_size);
 131         if (unlikely(!nilfs->ns_dat))
 132                 goto failed;
 133
 134         nilfs->ns_gc_dat = nilfs_dat_new(nilfs, dat_entry_size);
 135         if (unlikely(!nilfs->ns_gc_dat))
 136                 goto failed_dat;
 137
 138         nilfs->ns_cpfile = nilfs_cpfile_new(nilfs, checkpoint_size);
 139         if (unlikely(!nilfs->ns_cpfile))
 140                 goto failed_gc_dat;
 141
 142         nilfs->ns_sufile = nilfs_sufile_new(nilfs, segment_usage_size);
 143         if (unlikely(!nilfs->ns_sufile))
 144                 goto failed_cpfile;
 145
 146         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 147
 148         err = nilfs_dat_read(nilfs->ns_dat, (void *)bh_sr->b_data +
 149                              NILFS_SR_DAT_OFFSET(inode_size));
 150         if (unlikely(err))
 151                 goto failed_sufile;
 152
 153         err = nilfs_cpfile_read(nilfs->ns_cpfile, (void *)bh_sr->b_data +
 154                                 NILFS_SR_CPFILE_OFFSET(inode_size));
 155         if (unlikely(err))
 156                 goto failed_sufile;
 157
 158         err = nilfs_sufile_read(nilfs->ns_sufile, (void *)bh_sr->b_data +
 159                                 NILFS_SR_SUFILE_OFFSET(inode_size));
 160         if (unlikely(err))
 161                 goto failed_sufile;
 162
 163         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 164         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 165
 166  failed:
 167         brelse(bh_sr);
 168         return err;
 169
 170  failed_sufile:
 171         nilfs_mdt_destroy(nilfs->ns_sufile);
 172
 173  failed_cpfile:
 174         nilfs_mdt_destroy(nilfs->ns_cpfile);
 175
 176  failed_gc_dat:
 177         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 178
 179  failed_dat:
 180         nilfs_mdt_destroy(nilfs->ns_dat);
 181         goto failed;
 182 }
 183
 184 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 185 {
 186         memset(ri, 0, sizeof(*ri));
 187         INIT_LIST_HEAD(&ri->ri_used_segments);
 188 }
 189
 190 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 191 {
 192         nilfs_dispose_segment_list(&ri->ri_used_segments);
 193 }
 194
 195 /**
 196  * nilfs_store_log_cursor - load log cursor from a super block
 197  * @nilfs: nilfs object
 198  * @sbp: buffer storing super block to be read
 199  *
 200  * nilfs_store_log_cursor() reads the last position of the log
 201  * containing a super root from a given super block, and initializes
 202  * relevant information on the nilfs object preparatory for log
 203  * scanning and recovery.
 204  */
 205 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
 206                                   struct nilfs_super_block *sbp)
 207 {
 208         int ret = 0;
 209
 210         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 211         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 212         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 213
 214         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 215         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 216         nilfs->ns_segnum =
 217                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 218         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 219         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 220                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 221                 ret = -EINVAL;
 222         }
 223         return ret;
 224 }
 225
 226 /**
 227  * load_nilfs - load and recover the nilfs
 228  * @nilfs: the_nilfs structure to be released
 229  * @sbi: nilfs_sb_info used to recover past segment
 230  *
 231  * load_nilfs() searches and load the latest super root,
 232  * attaches the last segment, and does recovery if needed.
 233  * The caller must call this exclusively for simultaneous mounts.
 234  */
 235 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 236 {
 237         struct nilfs_recovery_info ri;
 238         unsigned int s_flags = sbi->s_super->s_flags;
 239         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 240         int valid_fs = nilfs_valid_fs(nilfs);
 241         int err;
 242
 243         if (!valid_fs) {
 244                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
 245                 if (s_flags & MS_RDONLY) {
 246                         printk(KERN_INFO "NILFS: INFO: recovery "
 247                                "required for readonly filesystem.\n");
 248                         printk(KERN_INFO "NILFS: write access will "
 249                                "be enabled during recovery.\n");
 250                 }
 251         }
 252
 253         nilfs_init_recovery_info(&ri);
 254
 255         err = nilfs_search_super_root(nilfs, &ri);
 256         if (unlikely(err)) {
 257                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 258                 int blocksize;
 259
 260                 if (err != -EINVAL)
 261                         goto scan_error;
 262
 263                 if (!nilfs_valid_sb(sbp[1])) {
 264                         printk(KERN_WARNING
 265                                "NILFS warning: unable to fall back to spare"
 266                                "super block\n");
 267                         goto scan_error;
 268                 }
 269                 printk(KERN_INFO
 270                        "NILFS: try rollback from an earlier position\n");
 271
 272                 /*
 273                  * restore super block with its spare and reconfigure
 274                  * relevant states of the nilfs object.
 275                  */
 276                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 277                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 278                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 279
 280                 /* verify consistency between two super blocks */
 281                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
 282                 if (blocksize != nilfs->ns_blocksize) {
 283                         printk(KERN_WARNING
 284                                "NILFS warning: blocksize differs between "
 285                                "two super blocks (%d != %d)\n",
 286                                blocksize, nilfs->ns_blocksize);
 287                         goto scan_error;
 288                 }
 289
 290                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 291                 if (err)
 292                         goto scan_error;
 293
 294                 /* drop clean flag to allow roll-forward and recovery */
 295                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 296                 valid_fs = 0;
 297
 298                 err = nilfs_search_super_root(nilfs, &ri);
 299                 if (err)
 300                         goto scan_error;
 301         }
 302
 303         err = nilfs_load_super_root(nilfs, ri.ri_super_root);
 304         if (unlikely(err)) {
 305                 printk(KERN_ERR "NILFS: error loading super root.\n");
 306                 goto failed;
 307         }
 308
 309         if (valid_fs)
 310                 goto skip_recovery;
 311
 312         if (s_flags & MS_RDONLY) {
 313                 __u64 features;
 314
 315                 if (nilfs_test_opt(sbi, NORECOVERY)) {
 316                         printk(KERN_INFO "NILFS: norecovery option specified. "
 317                                "skipping roll-forward recovery\n");
 318                         goto skip_recovery;
 319                 }
 320                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 321                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 322                 if (features) {
 323                         printk(KERN_ERR "NILFS: couldn't proceed with "
 324                                "recovery because of unsupported optional "
 325                                "features (%llx)\n",
 326                                (unsigned long long)features);
 327                         err = -EROFS;
 328                         goto failed_unload;
 329                 }
 330                 if (really_read_only) {
 331                         printk(KERN_ERR "NILFS: write access "
 332                                "unavailable, cannot proceed.\n");
 333                         err = -EROFS;
 334                         goto failed_unload;
 335                 }
 336                 sbi->s_super->s_flags &= ~MS_RDONLY;
 337         } else if (nilfs_test_opt(sbi, NORECOVERY)) {
 338                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
 339                        "option was specified for a read/write mount\n");
 340                 err = -EINVAL;
 341                 goto failed_unload;
 342         }
 343
 344         err = nilfs_salvage_orphan_logs(nilfs, sbi, &ri);
 345         if (err)
 346                 goto failed_unload;
 347
 348         down_write(&nilfs->ns_sem);
 349         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 350         err = nilfs_cleanup_super(sbi);
 351         up_write(&nilfs->ns_sem);
 352
 353         if (err) {
 354                 printk(KERN_ERR "NILFS: failed to update super block. "
 355                        "recovery unfinished.\n");
 356                 goto failed_unload;
 357         }
 358         printk(KERN_INFO "NILFS: recovery complete.\n");
 359
 360  skip_recovery:
 361         set_nilfs_loaded(nilfs);
 362         nilfs_clear_recovery_info(&ri);
 363         sbi->s_super->s_flags = s_flags;
 364         return 0;
 365
 366  scan_error:
 367         printk(KERN_ERR "NILFS: error searching super root.\n");
 368         goto failed;
 369
 370  failed_unload:
 371         nilfs_mdt_destroy(nilfs->ns_cpfile);
 372         nilfs_mdt_destroy(nilfs->ns_sufile);
 373         nilfs_mdt_destroy(nilfs->ns_dat);
 374         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 375
 376  failed:
 377         nilfs_clear_recovery_info(&ri);
 378         sbi->s_super->s_flags = s_flags;
 379         return err;
 380 }
 381
 382 static unsigned long long nilfs_max_size(unsigned int blkbits)
 383 {
 384         unsigned int max_bits;
 385         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 386
 387         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 388         if (max_bits < 64)
 389                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 390         return res;
 391 }
 392
 393 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 394                                    struct nilfs_super_block *sbp)
 395 {
 396         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 397                 printk(KERN_ERR "NILFS: unsupported revision "
 398                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 399                        "Please check the version of mkfs.nilfs.\n",
 400                        le32_to_cpu(sbp->s_rev_level),
 401                        le16_to_cpu(sbp->s_minor_rev_level),
 402                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 403                 return -EINVAL;
 404         }
 405         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 406         if (nilfs->ns_sbsize > BLOCK_SIZE)
 407                 return -EINVAL;
 408
 409         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 410         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 411
 412         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 413         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 414                 printk(KERN_ERR "NILFS: too short segment.\n");
 415                 return -EINVAL;
 416         }
 417
 418         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 419         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 420         nilfs->ns_r_segments_percentage =
 421                 le32_to_cpu(sbp->s_r_segments_percentage);
 422         nilfs->ns_nrsvsegs =
 423                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 424                       DIV_ROUND_UP(nilfs->ns_nsegments *
 425                                    nilfs->ns_r_segments_percentage, 100));
 426         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 427         return 0;
 428 }
 429
 430 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 431 {
 432         static unsigned char sum[4];
 433         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 434         size_t bytes;
 435         u32 crc;
 436
 437         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 438                 return 0;
 439         bytes = le16_to_cpu(sbp->s_bytes);
 440         if (bytes > BLOCK_SIZE)
 441                 return 0;
 442         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 443                        sumoff);
 444         crc = crc32_le(crc, sum, 4);
 445         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 446                        bytes - sumoff - 4);
 447         return crc == le32_to_cpu(sbp->s_sum);
 448 }
 449
 450 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 451 {
 452         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 453                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 454                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 455 }
 456
 457 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 458 {
 459         int i;
 460
 461         for (i = 0; i < 2; i++) {
 462                 if (nilfs->ns_sbp[i]) {
 463                         brelse(nilfs->ns_sbh[i]);
 464                         nilfs->ns_sbh[i] = NULL;
 465                         nilfs->ns_sbp[i] = NULL;
 466                 }
 467         }
 468 }
 469
 470 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 471 {
 472         brelse(nilfs->ns_sbh[0]);
 473         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 474         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 475         nilfs->ns_sbh[1] = NULL;
 476         nilfs->ns_sbp[1] = NULL;
 477 }
 478
 479 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 480 {
 481         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 482         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 483
 484         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 485         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 486         nilfs->ns_sbh[1] = tsbh;
 487         nilfs->ns_sbp[1] = tsbp;
 488 }
 489
 490 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 491                                   struct super_block *sb, int blocksize,
 492                                   struct nilfs_super_block **sbpp)
 493 {
 494         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 495         struct buffer_head **sbh = nilfs->ns_sbh;
 496         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 497         int valid[2], swp = 0;
 498
 499         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 500                                         &sbh[0]);
 501         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 502
 503         if (!sbp[0]) {
 504                 if (!sbp[1]) {
 505                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 506                         return -EIO;
 507                 }
 508                 printk(KERN_WARNING
 509                        "NILFS warning: unable to read primary superblock\n");
 510         } else if (!sbp[1])
 511                 printk(KERN_WARNING
 512                        "NILFS warning: unable to read secondary superblock\n");
 513
 514         /*
 515          * Compare two super blocks and set 1 in swp if the secondary
 516          * super block is valid and newer.  Otherwise, set 0 in swp.
 517          */
 518         valid[0] = nilfs_valid_sb(sbp[0]);
 519         valid[1] = nilfs_valid_sb(sbp[1]);
 520         swp = valid[1] && (!valid[0] ||
 521                            le64_to_cpu(sbp[1]->s_last_cno) >
 522                            le64_to_cpu(sbp[0]->s_last_cno));
 523
 524         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 525                 brelse(sbh[1]);
 526                 sbh[1] = NULL;
 527                 sbp[1] = NULL;
 528                 swp = 0;
 529         }
 530         if (!valid[swp]) {
 531                 nilfs_release_super_block(nilfs);
 532                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 533                        sb->s_id);
 534                 return -EINVAL;
 535         }
 536
 537         if (!valid[!swp])
 538                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 539                        "using spare superblock.\n");
 540         if (swp)
 541                 nilfs_swap_super_block(nilfs);
 542
 543         nilfs->ns_sbwcount = 0;
 544         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 545         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 546         *sbpp = sbp[0];
 547         return 0;
 548 }
 549
 550 /**
 551  * init_nilfs - initialize a NILFS instance.
 552  * @nilfs: the_nilfs structure
 553  * @sbi: nilfs_sb_info
 554  * @sb: super block
 555  * @data: mount options
 556  *
 557  * init_nilfs() performs common initialization per block device (e.g.
 558  * reading the super block, getting disk layout information, initializing
 559  * shared fields in the_nilfs).
 560  *
 561  * Return Value: On success, 0 is returned. On error, a negative error
 562  * code is returned.
 563  */
 564 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 565 {
 566         struct super_block *sb = sbi->s_super;
 567         struct nilfs_super_block *sbp;
 568         struct backing_dev_info *bdi;
 569         int blocksize;
 570         int err;
 571
 572         down_write(&nilfs->ns_sem);
 573
 574         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 575         if (!blocksize) {
 576                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 577                 err = -EINVAL;
 578                 goto out;
 579         }
 580         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 581         if (err)
 582                 goto out;
 583
 584         err = nilfs_store_magic_and_option(sb, sbp, data);
 585         if (err)
 586                 goto failed_sbh;
 587
 588         err = nilfs_check_feature_compatibility(sb, sbp);
 589         if (err)
 590                 goto failed_sbh;
 591
 592         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 593         if (blocksize < NILFS_MIN_BLOCK_SIZE ||
 594             blocksize > NILFS_MAX_BLOCK_SIZE) {
 595                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
 596                        "filesystem blocksize %d\n", blocksize);
 597                 err = -EINVAL;
 598                 goto failed_sbh;
 599         }
 600         if (sb->s_blocksize != blocksize) {
 601                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 602
 603                 if (blocksize < hw_blocksize) {
 604                         printk(KERN_ERR
 605                                "NILFS: blocksize %d too small for device "
 606                                "(sector-size = %d).\n",
 607                                blocksize, hw_blocksize);
 608                         err = -EINVAL;
 609                         goto failed_sbh;
 610                 }
 611                 nilfs_release_super_block(nilfs);
 612                 sb_set_blocksize(sb, blocksize);
 613
 614                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 615                 if (err)
 616                         goto out;
 617                         /* not failed_sbh; sbh is released automatically
 618                            when reloading fails. */
 619         }
 620         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 621         nilfs->ns_blocksize = blocksize;
 622
 623         err = nilfs_store_disk_layout(nilfs, sbp);
 624         if (err)
 625                 goto failed_sbh;
 626
 627         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 628
 629         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 630
 631         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 632         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 633
 634         err = nilfs_store_log_cursor(nilfs, sbp);
 635         if (err)
 636                 goto failed_sbh;
 637
 638         set_nilfs_init(nilfs);
 639         err = 0;
 640  out:
 641         up_write(&nilfs->ns_sem);
 642         return err;
 643
 644  failed_sbh:
 645         nilfs_release_super_block(nilfs);
 646         goto out;
 647 }
 648
 649 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 650                             size_t nsegs)
 651 {
 652         sector_t seg_start, seg_end;
 653         sector_t start = 0, nblocks = 0;
 654         unsigned int sects_per_block;
 655         __u64 *sn;
 656         int ret = 0;
 657
 658         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 659                 bdev_logical_block_size(nilfs->ns_bdev);
 660         for (sn = segnump; sn < segnump + nsegs; sn++) {
 661                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 662
 663                 if (!nblocks) {
 664                         start = seg_start;
 665                         nblocks = seg_end - seg_start + 1;
 666                 } else if (start + nblocks == seg_start) {
 667                         nblocks += seg_end - seg_start + 1;
 668                 } else {
 669                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 670                                                    start * sects_per_block,
 671                                                    nblocks * sects_per_block,
 672                                                    GFP_NOFS,
 673                                                    BLKDEV_IFL_WAIT |
 674                                                    BLKDEV_IFL_BARRIER);
 675                         if (ret < 0)
 676                                 return ret;
 677                         nblocks = 0;
 678                 }
 679         }
 680         if (nblocks)
 681                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 682                                            start * sects_per_block,
 683                                            nblocks * sects_per_block,
 684                                            GFP_NOFS,
 685                                           BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 686         return ret;
 687 }
 688
 689 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 690 {
 691         struct inode *dat = nilfs_dat_inode(nilfs);
 692         unsigned long ncleansegs;
 693
 694         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 695         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 696         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 697         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 698         return 0;
 699 }
 700
 701 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 702 {
 703         unsigned long ncleansegs, nincsegs;
 704
 705         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 706         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 707                 nilfs->ns_blocks_per_segment + 1;
 708
 709         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 710 }
 711
 712 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 713 {
 714         struct rb_node *n;
 715         struct nilfs_root *root;
 716
 717         spin_lock(&nilfs->ns_cptree_lock);
 718         n = nilfs->ns_cptree.rb_node;
 719         while (n) {
 720                 root = rb_entry(n, struct nilfs_root, rb_node);
 721
 722                 if (cno < root->cno) {
 723                         n = n->rb_left;
 724                 } else if (cno > root->cno) {
 725                         n = n->rb_right;
 726                 } else {
 727                         atomic_inc(&root->count);
 728                         spin_unlock(&nilfs->ns_cptree_lock);
 729                         return root;
 730                 }
 731         }
 732         spin_unlock(&nilfs->ns_cptree_lock);
 733
 734         return NULL;
 735 }
 736
 737 struct nilfs_root *
 738 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 739 {
 740         struct rb_node **p, *parent;
 741         struct nilfs_root *root, *new;
 742
 743         root = nilfs_lookup_root(nilfs, cno);
 744         if (root)
 745                 return root;
 746
 747         new = kmalloc(sizeof(*root), GFP_KERNEL);
 748         if (!new)
 749                 return NULL;
 750
 751         spin_lock(&nilfs->ns_cptree_lock);
 752
 753         p = &nilfs->ns_cptree.rb_node;
 754         parent = NULL;
 755
 756         while (*p) {
 757                 parent = *p;
 758                 root = rb_entry(parent, struct nilfs_root, rb_node);
 759
 760                 if (cno < root->cno) {
 761                         p = &(*p)->rb_left;
 762                 } else if (cno > root->cno) {
 763                         p = &(*p)->rb_right;
 764                 } else {
 765                         atomic_inc(&root->count);
 766                         spin_unlock(&nilfs->ns_cptree_lock);
 767                         kfree(new);
 768                         return root;
 769                 }
 770         }
 771
 772         new->cno = cno;
 773         new->ifile = NULL;
 774         new->nilfs = nilfs;
 775         atomic_set(&new->count, 1);
 776         atomic_set(&new->inodes_count, 0);
 777         atomic_set(&new->blocks_count, 0);
 778
 779         rb_link_node(&new->rb_node, parent, p);
 780         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 781
 782         spin_unlock(&nilfs->ns_cptree_lock);
 783
 784         return new;
 785 }
 786
 787 void nilfs_put_root(struct nilfs_root *root)
 788 {
 789         if (atomic_dec_and_test(&root->count)) {
 790                 struct the_nilfs *nilfs = root->nilfs;
 791
 792                 spin_lock(&nilfs->ns_cptree_lock);
 793                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 794                 spin_unlock(&nilfs->ns_cptree_lock);
 795                 if (root->ifile)
 796                         nilfs_mdt_destroy(root->ifile);
 797
 798                 kfree(root);
 799         }
 800 }
 801
 802 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 803                                 int snapshot_mount)
 804 {
 805         struct nilfs_root *root;
 806         int ret;
 807
 808         if (cno < 0 || cno > nilfs->ns_cno)
 809                 return false;
 810
 811         if (cno >= nilfs_last_cno(nilfs))
 812                 return true;    /* protect recent checkpoints */
 813
 814         ret = false;
 815         root = nilfs_lookup_root(nilfs, cno);
 816         if (root) {
 817                 ret = true;
 818                 nilfs_put_root(root);
 819         }
 820         return ret;
 821 }