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 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  38                             sector_t start_blocknr, u64 seq, __u64 cno)
  39 {
  40         spin_lock(&nilfs->ns_last_segment_lock);
  41         nilfs->ns_last_pseg = start_blocknr;
  42         nilfs->ns_last_seq = seq;
  43         nilfs->ns_last_cno = cno;
  44         spin_unlock(&nilfs->ns_last_segment_lock);
  45 }
  46
  47 /**
  48  * alloc_nilfs - allocate the_nilfs structure
  49  * @bdev: block device to which the_nilfs is related
  50  *
  51  * alloc_nilfs() allocates memory for the_nilfs and
  52  * initializes its reference count and locks.
  53  *
  54  * Return Value: On success, pointer to the_nilfs is returned.
  55  * On error, NULL is returned.
  56  */
  57 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  58 {
  59         struct the_nilfs *nilfs;
  60
  61         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  62         if (!nilfs)
  63                 return NULL;
  64
  65         nilfs->ns_bdev = bdev;
  66         atomic_set(&nilfs->ns_count, 1);
  67         atomic_set(&nilfs->ns_writer_refcount, -1);
  68         atomic_set(&nilfs->ns_ndirtyblks, 0);
  69         init_rwsem(&nilfs->ns_sem);
  70         mutex_init(&nilfs->ns_writer_mutex);
  71         INIT_LIST_HEAD(&nilfs->ns_supers);
  72         spin_lock_init(&nilfs->ns_last_segment_lock);
  73         nilfs->ns_gc_inodes_h = NULL;
  74         init_rwsem(&nilfs->ns_segctor_sem);
  75
  76         return nilfs;
  77 }
  78
  79 /**
  80  * put_nilfs - release a reference to the_nilfs
  81  * @nilfs: the_nilfs structure to be released
  82  *
  83  * put_nilfs() decrements a reference counter of the_nilfs.
  84  * If the reference count reaches zero, the_nilfs is freed.
  85  */
  86 void put_nilfs(struct the_nilfs *nilfs)
  87 {
  88         if (!atomic_dec_and_test(&nilfs->ns_count))
  89                 return;
  90         /*
  91          * Increment of ns_count never occur below because the caller
  92          * of get_nilfs() holds at least one reference to the_nilfs.
  93          * Thus its exclusion control is not required here.
  94          */
  95         might_sleep();
  96         if (nilfs_loaded(nilfs)) {
  97                 nilfs_mdt_clear(nilfs->ns_sufile);
  98                 nilfs_mdt_destroy(nilfs->ns_sufile);
  99                 nilfs_mdt_clear(nilfs->ns_cpfile);
 100                 nilfs_mdt_destroy(nilfs->ns_cpfile);
 101                 nilfs_mdt_clear(nilfs->ns_dat);
 102                 nilfs_mdt_destroy(nilfs->ns_dat);
 103                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
 104                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 105         }
 106         if (nilfs_init(nilfs)) {
 107                 nilfs_destroy_gccache(nilfs);
 108                 brelse(nilfs->ns_sbh[0]);
 109                 brelse(nilfs->ns_sbh[1]);
 110         }
 111         kfree(nilfs);
 112 }
 113
 114 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 115                                  struct nilfs_sb_info *sbi, sector_t sr_block)
 116 {
 117         static struct lock_class_key dat_lock_key;
 118         struct buffer_head *bh_sr;
 119         struct nilfs_super_root *raw_sr;
 120         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 121         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 122         unsigned inode_size;
 123         int err;
 124
 125         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
 126         if (unlikely(err))
 127                 return err;
 128
 129         down_read(&nilfs->ns_sem);
 130         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 131         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 132         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 133         up_read(&nilfs->ns_sem);
 134
 135         inode_size = nilfs->ns_inode_size;
 136
 137         err = -ENOMEM;
 138         nilfs->ns_dat = nilfs_mdt_new(
 139                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 140         if (unlikely(!nilfs->ns_dat))
 141                 goto failed;
 142
 143         nilfs->ns_gc_dat = nilfs_mdt_new(
 144                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 145         if (unlikely(!nilfs->ns_gc_dat))
 146                 goto failed_dat;
 147
 148         nilfs->ns_cpfile = nilfs_mdt_new(
 149                 nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
 150         if (unlikely(!nilfs->ns_cpfile))
 151                 goto failed_gc_dat;
 152
 153         nilfs->ns_sufile = nilfs_mdt_new(
 154                 nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
 155         if (unlikely(!nilfs->ns_sufile))
 156                 goto failed_cpfile;
 157
 158         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
 159         if (unlikely(err))
 160                 goto failed_sufile;
 161
 162         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
 163         if (unlikely(err))
 164                 goto failed_sufile;
 165
 166         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
 167         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
 168
 169         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 170         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
 171                                  sizeof(struct nilfs_cpfile_header));
 172         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
 173                                  sizeof(struct nilfs_sufile_header));
 174
 175         err = nilfs_mdt_read_inode_direct(
 176                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
 177         if (unlikely(err))
 178                 goto failed_sufile;
 179
 180         err = nilfs_mdt_read_inode_direct(
 181                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
 182         if (unlikely(err))
 183                 goto failed_sufile;
 184
 185         err = nilfs_mdt_read_inode_direct(
 186                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
 187         if (unlikely(err))
 188                 goto failed_sufile;
 189
 190         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 191         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 192
 193  failed:
 194         brelse(bh_sr);
 195         return err;
 196
 197  failed_sufile:
 198         nilfs_mdt_destroy(nilfs->ns_sufile);
 199
 200  failed_cpfile:
 201         nilfs_mdt_destroy(nilfs->ns_cpfile);
 202
 203  failed_gc_dat:
 204         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 205
 206  failed_dat:
 207         nilfs_mdt_destroy(nilfs->ns_dat);
 208         goto failed;
 209 }
 210
 211 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 212 {
 213         memset(ri, 0, sizeof(*ri));
 214         INIT_LIST_HEAD(&ri->ri_used_segments);
 215 }
 216
 217 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 218 {
 219         nilfs_dispose_segment_list(&ri->ri_used_segments);
 220 }
 221
 222 /**
 223  * load_nilfs - load and recover the nilfs
 224  * @nilfs: the_nilfs structure to be released
 225  * @sbi: nilfs_sb_info used to recover past segment
 226  *
 227  * load_nilfs() searches and load the latest super root,
 228  * attaches the last segment, and does recovery if needed.
 229  * The caller must call this exclusively for simultaneous mounts.
 230  */
 231 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 232 {
 233         struct nilfs_recovery_info ri;
 234         unsigned int s_flags = sbi->s_super->s_flags;
 235         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 236         unsigned valid_fs;
 237         int err = 0;
 238
 239         nilfs_init_recovery_info(&ri);
 240
 241         down_write(&nilfs->ns_sem);
 242         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 243         up_write(&nilfs->ns_sem);
 244
 245         if (!valid_fs && (s_flags & MS_RDONLY)) {
 246                 printk(KERN_INFO "NILFS: INFO: recovery "
 247                        "required for readonly filesystem.\n");
 248                 if (really_read_only) {
 249                         printk(KERN_ERR "NILFS: write access "
 250                                "unavailable, cannot proceed.\n");
 251                         err = -EROFS;
 252                         goto failed;
 253                 }
 254                 printk(KERN_INFO "NILFS: write access will "
 255                        "be enabled during recovery.\n");
 256                 sbi->s_super->s_flags &= ~MS_RDONLY;
 257         }
 258
 259         err = nilfs_search_super_root(nilfs, sbi, &ri);
 260         if (unlikely(err)) {
 261                 printk(KERN_ERR "NILFS: error searching super root.\n");
 262                 goto failed;
 263         }
 264
 265         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
 266         if (unlikely(err)) {
 267                 printk(KERN_ERR "NILFS: error loading super root.\n");
 268                 goto failed;
 269         }
 270
 271         if (!valid_fs) {
 272                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
 273                 if (unlikely(err)) {
 274                         nilfs_mdt_destroy(nilfs->ns_cpfile);
 275                         nilfs_mdt_destroy(nilfs->ns_sufile);
 276                         nilfs_mdt_destroy(nilfs->ns_dat);
 277                         goto failed;
 278                 }
 279                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
 280                         sbi->s_super->s_dirt = 1;
 281         }
 282
 283         set_nilfs_loaded(nilfs);
 284
 285  failed:
 286         nilfs_clear_recovery_info(&ri);
 287         sbi->s_super->s_flags = s_flags;
 288         return err;
 289 }
 290
 291 static unsigned long long nilfs_max_size(unsigned int blkbits)
 292 {
 293         unsigned int max_bits;
 294         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 295
 296         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 297         if (max_bits < 64)
 298                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 299         return res;
 300 }
 301
 302 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 303                                    struct nilfs_super_block *sbp)
 304 {
 305         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 306                 printk(KERN_ERR "NILFS: revision mismatch "
 307                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 308                        "Please check the version of mkfs.nilfs.\n",
 309                        le32_to_cpu(sbp->s_rev_level),
 310                        le16_to_cpu(sbp->s_minor_rev_level),
 311                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 312                 return -EINVAL;
 313         }
 314         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 315         if (nilfs->ns_sbsize > BLOCK_SIZE)
 316                 return -EINVAL;
 317
 318         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 319         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 320
 321         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 322         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 323                 printk(KERN_ERR "NILFS: too short segment. \n");
 324                 return -EINVAL;
 325         }
 326
 327         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 328         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 329         nilfs->ns_r_segments_percentage =
 330                 le32_to_cpu(sbp->s_r_segments_percentage);
 331         nilfs->ns_nrsvsegs =
 332                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 333                       DIV_ROUND_UP(nilfs->ns_nsegments *
 334                                    nilfs->ns_r_segments_percentage, 100));
 335         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 336         return 0;
 337 }
 338
 339 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 340 {
 341         static unsigned char sum[4];
 342         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 343         size_t bytes;
 344         u32 crc;
 345
 346         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 347                 return 0;
 348         bytes = le16_to_cpu(sbp->s_bytes);
 349         if (bytes > BLOCK_SIZE)
 350                 return 0;
 351         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 352                        sumoff);
 353         crc = crc32_le(crc, sum, 4);
 354         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 355                        bytes - sumoff - 4);
 356         return crc == le32_to_cpu(sbp->s_sum);
 357 }
 358
 359 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 360 {
 361         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 362                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 363                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 364 }
 365
 366 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 367 {
 368         int i;
 369
 370         for (i = 0; i < 2; i++) {
 371                 if (nilfs->ns_sbp[i]) {
 372                         brelse(nilfs->ns_sbh[i]);
 373                         nilfs->ns_sbh[i] = NULL;
 374                         nilfs->ns_sbp[i] = NULL;
 375                 }
 376         }
 377 }
 378
 379 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 380 {
 381         brelse(nilfs->ns_sbh[0]);
 382         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 383         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 384         nilfs->ns_sbh[1] = NULL;
 385         nilfs->ns_sbp[1] = NULL;
 386 }
 387
 388 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 389 {
 390         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 391         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 392
 393         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 394         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 395         nilfs->ns_sbh[1] = tsbh;
 396         nilfs->ns_sbp[1] = tsbp;
 397 }
 398
 399 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 400                                   struct super_block *sb, int blocksize,
 401                                   struct nilfs_super_block **sbpp)
 402 {
 403         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 404         struct buffer_head **sbh = nilfs->ns_sbh;
 405         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 406         int valid[2], swp = 0;
 407
 408         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 409                                         &sbh[0]);
 410         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 411
 412         if (!sbp[0]) {
 413                 if (!sbp[1]) {
 414                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 415                         return -EIO;
 416                 }
 417                 printk(KERN_WARNING
 418                        "NILFS warning: unable to read primary superblock\n");
 419         } else if (!sbp[1])
 420                 printk(KERN_WARNING
 421                        "NILFS warning: unable to read secondary superblock\n");
 422
 423         valid[0] = nilfs_valid_sb(sbp[0]);
 424         valid[1] = nilfs_valid_sb(sbp[1]);
 425         swp = valid[1] &&
 426                 (!valid[0] ||
 427                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
 428
 429         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 430                 brelse(sbh[1]);
 431                 sbh[1] = NULL;
 432                 sbp[1] = NULL;
 433                 swp = 0;
 434         }
 435         if (!valid[swp]) {
 436                 nilfs_release_super_block(nilfs);
 437                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 438                        sb->s_id);
 439                 return -EINVAL;
 440         }
 441
 442         if (swp) {
 443                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 444                        "using spare superblock.\n");
 445                 nilfs_swap_super_block(nilfs);
 446         }
 447
 448         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
 449         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
 450         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 451         *sbpp = sbp[0];
 452         return 0;
 453 }
 454
 455 /**
 456  * init_nilfs - initialize a NILFS instance.
 457  * @nilfs: the_nilfs structure
 458  * @sbi: nilfs_sb_info
 459  * @sb: super block
 460  * @data: mount options
 461  *
 462  * init_nilfs() performs common initialization per block device (e.g.
 463  * reading the super block, getting disk layout information, initializing
 464  * shared fields in the_nilfs). It takes on some portion of the jobs
 465  * typically done by a fill_super() routine. This division arises from
 466  * the nature that multiple NILFS instances may be simultaneously
 467  * mounted on a device.
 468  * For multiple mounts on the same device, only the first mount
 469  * invokes these tasks.
 470  *
 471  * Return Value: On success, 0 is returned. On error, a negative error
 472  * code is returned.
 473  */
 474 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 475 {
 476         struct super_block *sb = sbi->s_super;
 477         struct nilfs_super_block *sbp;
 478         struct backing_dev_info *bdi;
 479         int blocksize;
 480         int err;
 481
 482         down_write(&nilfs->ns_sem);
 483         if (nilfs_init(nilfs)) {
 484                 /* Load values from existing the_nilfs */
 485                 sbp = nilfs->ns_sbp[0];
 486                 err = nilfs_store_magic_and_option(sb, sbp, data);
 487                 if (err)
 488                         goto out;
 489
 490                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 491                 if (sb->s_blocksize != blocksize &&
 492                     !sb_set_blocksize(sb, blocksize)) {
 493                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 494                                blocksize);
 495                         err = -EINVAL;
 496                 }
 497                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 498                 goto out;
 499         }
 500
 501         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 502         if (!blocksize) {
 503                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 504                 err = -EINVAL;
 505                 goto out;
 506         }
 507         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 508         if (err)
 509                 goto out;
 510
 511         err = nilfs_store_magic_and_option(sb, sbp, data);
 512         if (err)
 513                 goto failed_sbh;
 514
 515         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 516         if (sb->s_blocksize != blocksize) {
 517                 int hw_blocksize = bdev_hardsect_size(sb->s_bdev);
 518
 519                 if (blocksize < hw_blocksize) {
 520                         printk(KERN_ERR
 521                                "NILFS: blocksize %d too small for device "
 522                                "(sector-size = %d).\n",
 523                                blocksize, hw_blocksize);
 524                         err = -EINVAL;
 525                         goto failed_sbh;
 526                 }
 527                 nilfs_release_super_block(nilfs);
 528                 sb_set_blocksize(sb, blocksize);
 529
 530                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 531                 if (err)
 532                         goto out;
 533                         /* not failed_sbh; sbh is released automatically
 534                            when reloading fails. */
 535         }
 536         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 537
 538         err = nilfs_store_disk_layout(nilfs, sbp);
 539         if (err)
 540                 goto failed_sbh;
 541
 542         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 543
 544         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 545
 546         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
 547         if (!bdi)
 548                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 549         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 550
 551         /* Finding last segment */
 552         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 553         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 554         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 555
 556         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 557         nilfs->ns_segnum =
 558                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 559         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 560         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 561                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 562                 err = -EINVAL;
 563                 goto failed_sbh;
 564         }
 565         /* Dummy values  */
 566         nilfs->ns_free_segments_count =
 567                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
 568
 569         /* Initialize gcinode cache */
 570         err = nilfs_init_gccache(nilfs);
 571         if (err)
 572                 goto failed_sbh;
 573
 574         set_nilfs_init(nilfs);
 575         err = 0;
 576  out:
 577         up_write(&nilfs->ns_sem);
 578         return err;
 579
 580  failed_sbh:
 581         nilfs_release_super_block(nilfs);
 582         goto out;
 583 }
 584
 585 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 586 {
 587         struct inode *dat = nilfs_dat_inode(nilfs);
 588         unsigned long ncleansegs;
 589         int err;
 590
 591         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 592         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
 593         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 594         if (likely(!err))
 595                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 596         return err;
 597 }
 598
 599 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 600 {
 601         struct inode *sufile = nilfs->ns_sufile;
 602         unsigned long ncleansegs, nincsegs;
 603         int ret;
 604
 605         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
 606         if (likely(!ret)) {
 607                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 608                         nilfs->ns_blocks_per_segment + 1;
 609                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
 610                         ret++;
 611         }
 612         return ret;
 613 }
 614
 615 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 616                                 int snapshot_mount)
 617 {
 618         struct nilfs_sb_info *sbi;
 619         int ret = 0;
 620
 621         down_read(&nilfs->ns_sem);
 622         if (cno == 0 || cno > nilfs->ns_cno)
 623                 goto out_unlock;
 624
 625         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 626                 if (sbi->s_snapshot_cno == cno &&
 627                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 628                                         /* exclude read-only mounts */
 629                         ret++;
 630                         break;
 631                 }
 632         }
 633         /* for protecting recent checkpoints */
 634         if (cno >= nilfs_last_cno(nilfs))
 635                 ret++;
 636
 637  out_unlock:
 638         up_read(&nilfs->ns_sem);
 639         return ret;
 640 }