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 "seglist.h"
  36 #include "segbuf.h"
  37
  38 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  39                             sector_t start_blocknr, u64 seq, __u64 cno)
  40 {
  41         spin_lock(&nilfs->ns_last_segment_lock);
  42         nilfs->ns_last_pseg = start_blocknr;
  43         nilfs->ns_last_seq = seq;
  44         nilfs->ns_last_cno = cno;
  45         spin_unlock(&nilfs->ns_last_segment_lock);
  46 }
  47
  48 /**
  49  * alloc_nilfs - allocate the_nilfs structure
  50  * @bdev: block device to which the_nilfs is related
  51  *
  52  * alloc_nilfs() allocates memory for the_nilfs and
  53  * initializes its reference count and locks.
  54  *
  55  * Return Value: On success, pointer to the_nilfs is returned.
  56  * On error, NULL is returned.
  57  */
  58 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  59 {
  60         struct the_nilfs *nilfs;
  61
  62         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  63         if (!nilfs)
  64                 return NULL;
  65
  66         nilfs->ns_bdev = bdev;
  67         atomic_set(&nilfs->ns_count, 1);
  68         atomic_set(&nilfs->ns_writer_refcount, -1);
  69         atomic_set(&nilfs->ns_ndirtyblks, 0);
  70         init_rwsem(&nilfs->ns_sem);
  71         mutex_init(&nilfs->ns_writer_mutex);
  72         INIT_LIST_HEAD(&nilfs->ns_supers);
  73         spin_lock_init(&nilfs->ns_last_segment_lock);
  74         nilfs->ns_gc_inodes_h = NULL;
  75         init_rwsem(&nilfs->ns_segctor_sem);
  76
  77         return nilfs;
  78 }
  79
  80 /**
  81  * put_nilfs - release a reference to the_nilfs
  82  * @nilfs: the_nilfs structure to be released
  83  *
  84  * put_nilfs() decrements a reference counter of the_nilfs.
  85  * If the reference count reaches zero, the_nilfs is freed.
  86  */
  87 void put_nilfs(struct the_nilfs *nilfs)
  88 {
  89         if (!atomic_dec_and_test(&nilfs->ns_count))
  90                 return;
  91         /*
  92          * Increment of ns_count never occur below because the caller
  93          * of get_nilfs() holds at least one reference to the_nilfs.
  94          * Thus its exclusion control is not required here.
  95          */
  96         might_sleep();
  97         if (nilfs_loaded(nilfs)) {
  98                 nilfs_mdt_clear(nilfs->ns_sufile);
  99                 nilfs_mdt_destroy(nilfs->ns_sufile);
 100                 nilfs_mdt_clear(nilfs->ns_cpfile);
 101                 nilfs_mdt_destroy(nilfs->ns_cpfile);
 102                 nilfs_mdt_clear(nilfs->ns_dat);
 103                 nilfs_mdt_destroy(nilfs->ns_dat);
 104                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
 105                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 106         }
 107         if (nilfs_init(nilfs)) {
 108                 nilfs_destroy_gccache(nilfs);
 109                 brelse(nilfs->ns_sbh[0]);
 110                 brelse(nilfs->ns_sbh[1]);
 111         }
 112         kfree(nilfs);
 113 }
 114
 115 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 116                                  struct nilfs_sb_info *sbi, sector_t sr_block)
 117 {
 118         static struct lock_class_key dat_lock_key;
 119         struct buffer_head *bh_sr;
 120         struct nilfs_super_root *raw_sr;
 121         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 122         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 123         unsigned inode_size;
 124         int err;
 125
 126         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
 127         if (unlikely(err))
 128                 return err;
 129
 130         down_read(&nilfs->ns_sem);
 131         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 132         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 133         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 134         up_read(&nilfs->ns_sem);
 135
 136         inode_size = nilfs->ns_inode_size;
 137
 138         err = -ENOMEM;
 139         nilfs->ns_dat = nilfs_mdt_new(
 140                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 141         if (unlikely(!nilfs->ns_dat))
 142                 goto failed;
 143
 144         nilfs->ns_gc_dat = nilfs_mdt_new(
 145                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 146         if (unlikely(!nilfs->ns_gc_dat))
 147                 goto failed_dat;
 148
 149         nilfs->ns_cpfile = nilfs_mdt_new(
 150                 nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
 151         if (unlikely(!nilfs->ns_cpfile))
 152                 goto failed_gc_dat;
 153
 154         nilfs->ns_sufile = nilfs_mdt_new(
 155                 nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
 156         if (unlikely(!nilfs->ns_sufile))
 157                 goto failed_cpfile;
 158
 159         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
 160         if (unlikely(err))
 161                 goto failed_sufile;
 162
 163         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
 164         if (unlikely(err))
 165                 goto failed_sufile;
 166
 167         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
 168         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
 169
 170         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 171         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
 172                                  sizeof(struct nilfs_cpfile_header));
 173         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
 174                                  sizeof(struct nilfs_sufile_header));
 175
 176         err = nilfs_mdt_read_inode_direct(
 177                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
 178         if (unlikely(err))
 179                 goto failed_sufile;
 180
 181         err = nilfs_mdt_read_inode_direct(
 182                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
 183         if (unlikely(err))
 184                 goto failed_sufile;
 185
 186         err = nilfs_mdt_read_inode_direct(
 187                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
 188         if (unlikely(err))
 189                 goto failed_sufile;
 190
 191         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 192         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 193
 194  failed:
 195         brelse(bh_sr);
 196         return err;
 197
 198  failed_sufile:
 199         nilfs_mdt_destroy(nilfs->ns_sufile);
 200
 201  failed_cpfile:
 202         nilfs_mdt_destroy(nilfs->ns_cpfile);
 203
 204  failed_gc_dat:
 205         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 206
 207  failed_dat:
 208         nilfs_mdt_destroy(nilfs->ns_dat);
 209         goto failed;
 210 }
 211
 212 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 213 {
 214         memset(ri, 0, sizeof(*ri));
 215         INIT_LIST_HEAD(&ri->ri_used_segments);
 216 }
 217
 218 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 219 {
 220         nilfs_dispose_segment_list(&ri->ri_used_segments);
 221 }
 222
 223 /**
 224  * load_nilfs - load and recover the nilfs
 225  * @nilfs: the_nilfs structure to be released
 226  * @sbi: nilfs_sb_info 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 nilfs_sb_info *sbi)
 233 {
 234         struct nilfs_recovery_info ri;
 235         unsigned int s_flags = sbi->s_super->s_flags;
 236         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 237         unsigned valid_fs;
 238         int err = 0;
 239
 240         nilfs_init_recovery_info(&ri);
 241
 242         down_write(&nilfs->ns_sem);
 243         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 244         up_write(&nilfs->ns_sem);
 245
 246         if (!valid_fs && (s_flags & MS_RDONLY)) {
 247                 printk(KERN_INFO "NILFS: INFO: recovery "
 248                        "required for readonly filesystem.\n");
 249                 if (really_read_only) {
 250                         printk(KERN_ERR "NILFS: write access "
 251                                "unavailable, cannot proceed.\n");
 252                         err = -EROFS;
 253                         goto failed;
 254                 }
 255                 printk(KERN_INFO "NILFS: write access will "
 256                        "be enabled during recovery.\n");
 257                 sbi->s_super->s_flags &= ~MS_RDONLY;
 258         }
 259
 260         err = nilfs_search_super_root(nilfs, sbi, &ri);
 261         if (unlikely(err)) {
 262                 printk(KERN_ERR "NILFS: error searching super root.\n");
 263                 goto failed;
 264         }
 265
 266         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
 267         if (unlikely(err)) {
 268                 printk(KERN_ERR "NILFS: error loading super root.\n");
 269                 goto failed;
 270         }
 271
 272         if (!valid_fs) {
 273                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
 274                 if (unlikely(err)) {
 275                         nilfs_mdt_destroy(nilfs->ns_cpfile);
 276                         nilfs_mdt_destroy(nilfs->ns_sufile);
 277                         nilfs_mdt_destroy(nilfs->ns_dat);
 278                         goto failed;
 279                 }
 280                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
 281                         sbi->s_super->s_dirt = 1;
 282         }
 283
 284         set_nilfs_loaded(nilfs);
 285
 286  failed:
 287         nilfs_clear_recovery_info(&ri);
 288         sbi->s_super->s_flags = s_flags;
 289         return err;
 290 }
 291
 292 static unsigned long long nilfs_max_size(unsigned int blkbits)
 293 {
 294         unsigned int max_bits;
 295         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 296
 297         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 298         if (max_bits < 64)
 299                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 300         return res;
 301 }
 302
 303 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 304                                    struct nilfs_super_block *sbp)
 305 {
 306         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 307                 printk(KERN_ERR "NILFS: revision mismatch "
 308                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 309                        "Please check the version of mkfs.nilfs.\n",
 310                        le32_to_cpu(sbp->s_rev_level),
 311                        le16_to_cpu(sbp->s_minor_rev_level),
 312                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 313                 return -EINVAL;
 314         }
 315         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 316         if (nilfs->ns_sbsize > BLOCK_SIZE)
 317                 return -EINVAL;
 318
 319         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 320         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 321
 322         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 323         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 324                 printk(KERN_ERR "NILFS: too short segment. \n");
 325                 return -EINVAL;
 326         }
 327
 328         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 329         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 330         nilfs->ns_r_segments_percentage =
 331                 le32_to_cpu(sbp->s_r_segments_percentage);
 332         nilfs->ns_nrsvsegs =
 333                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 334                       DIV_ROUND_UP(nilfs->ns_nsegments *
 335                                    nilfs->ns_r_segments_percentage, 100));
 336         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 337         return 0;
 338 }
 339
 340 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 341 {
 342         static unsigned char sum[4];
 343         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 344         size_t bytes;
 345         u32 crc;
 346
 347         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 348                 return 0;
 349         bytes = le16_to_cpu(sbp->s_bytes);
 350         if (bytes > BLOCK_SIZE)
 351                 return 0;
 352         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 353                        sumoff);
 354         crc = crc32_le(crc, sum, 4);
 355         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 356                        bytes - sumoff - 4);
 357         return crc == le32_to_cpu(sbp->s_sum);
 358 }
 359
 360 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 361 {
 362         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 363                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 364                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 365 }
 366
 367 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 368 {
 369         int i;
 370
 371         for (i = 0; i < 2; i++) {
 372                 if (nilfs->ns_sbp[i]) {
 373                         brelse(nilfs->ns_sbh[i]);
 374                         nilfs->ns_sbh[i] = NULL;
 375                         nilfs->ns_sbp[i] = NULL;
 376                 }
 377         }
 378 }
 379
 380 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 381 {
 382         brelse(nilfs->ns_sbh[0]);
 383         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 384         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 385         nilfs->ns_sbh[1] = NULL;
 386         nilfs->ns_sbp[1] = NULL;
 387 }
 388
 389 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 390 {
 391         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 392         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 393
 394         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 395         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 396         nilfs->ns_sbh[1] = tsbh;
 397         nilfs->ns_sbp[1] = tsbp;
 398 }
 399
 400 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 401                                   struct super_block *sb, int blocksize,
 402                                   struct nilfs_super_block **sbpp)
 403 {
 404         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 405         struct buffer_head **sbh = nilfs->ns_sbh;
 406         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 407         int valid[2], swp = 0;
 408
 409         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 410                                         &sbh[0]);
 411         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 412
 413         if (!sbp[0]) {
 414                 if (!sbp[1]) {
 415                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 416                         return -EIO;
 417                 }
 418                 printk(KERN_WARNING
 419                        "NILFS warning: unable to read primary superblock\n");
 420         } else if (!sbp[1])
 421                 printk(KERN_WARNING
 422                        "NILFS warning: unable to read secondary superblock\n");
 423
 424         valid[0] = nilfs_valid_sb(sbp[0]);
 425         valid[1] = nilfs_valid_sb(sbp[1]);
 426         swp = valid[1] &&
 427                 (!valid[0] ||
 428                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
 429
 430         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 431                 brelse(sbh[1]);
 432                 sbh[1] = NULL;
 433                 sbp[1] = NULL;
 434                 swp = 0;
 435         }
 436         if (!valid[swp]) {
 437                 nilfs_release_super_block(nilfs);
 438                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 439                        sb->s_id);
 440                 return -EINVAL;
 441         }
 442
 443         if (swp) {
 444                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 445                        "using spare superblock.\n");
 446                 nilfs_swap_super_block(nilfs);
 447         }
 448
 449         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
 450         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
 451         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 452         *sbpp = sbp[0];
 453         return 0;
 454 }
 455
 456 /**
 457  * init_nilfs - initialize a NILFS instance.
 458  * @nilfs: the_nilfs structure
 459  * @sbi: nilfs_sb_info
 460  * @sb: super block
 461  * @data: mount options
 462  *
 463  * init_nilfs() performs common initialization per block device (e.g.
 464  * reading the super block, getting disk layout information, initializing
 465  * shared fields in the_nilfs). It takes on some portion of the jobs
 466  * typically done by a fill_super() routine. This division arises from
 467  * the nature that multiple NILFS instances may be simultaneously
 468  * mounted on a device.
 469  * For multiple mounts on the same device, only the first mount
 470  * invokes these tasks.
 471  *
 472  * Return Value: On success, 0 is returned. On error, a negative error
 473  * code is returned.
 474  */
 475 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 476 {
 477         struct super_block *sb = sbi->s_super;
 478         struct nilfs_super_block *sbp;
 479         struct backing_dev_info *bdi;
 480         int blocksize;
 481         int err;
 482
 483         down_write(&nilfs->ns_sem);
 484         if (nilfs_init(nilfs)) {
 485                 /* Load values from existing the_nilfs */
 486                 sbp = nilfs->ns_sbp[0];
 487                 err = nilfs_store_magic_and_option(sb, sbp, data);
 488                 if (err)
 489                         goto out;
 490
 491                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 492                 if (sb->s_blocksize != blocksize &&
 493                     !sb_set_blocksize(sb, blocksize)) {
 494                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 495                                blocksize);
 496                         err = -EINVAL;
 497                 }
 498                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 499                 goto out;
 500         }
 501
 502         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 503         if (!blocksize) {
 504                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 505                 err = -EINVAL;
 506                 goto out;
 507         }
 508         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 509         if (err)
 510                 goto out;
 511
 512         err = nilfs_store_magic_and_option(sb, sbp, data);
 513         if (err)
 514                 goto failed_sbh;
 515
 516         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 517         if (sb->s_blocksize != blocksize) {
 518                 int hw_blocksize = bdev_hardsect_size(sb->s_bdev);
 519
 520                 if (blocksize < hw_blocksize) {
 521                         printk(KERN_ERR
 522                                "NILFS: blocksize %d too small for device "
 523                                "(sector-size = %d).\n",
 524                                blocksize, hw_blocksize);
 525                         err = -EINVAL;
 526                         goto failed_sbh;
 527                 }
 528                 nilfs_release_super_block(nilfs);
 529                 sb_set_blocksize(sb, blocksize);
 530
 531                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 532                 if (err)
 533                         goto out;
 534                         /* not failed_sbh; sbh is released automatically
 535                            when reloading fails. */
 536         }
 537         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 538
 539         err = nilfs_store_disk_layout(nilfs, sbp);
 540         if (err)
 541                 goto failed_sbh;
 542
 543         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 544
 545         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 546
 547         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
 548         if (!bdi)
 549                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 550         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 551
 552         /* Finding last segment */
 553         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 554         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 555         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 556
 557         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 558         nilfs->ns_segnum =
 559                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 560         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 561         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 562                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 563                 err = -EINVAL;
 564                 goto failed_sbh;
 565         }
 566         /* Dummy values  */
 567         nilfs->ns_free_segments_count =
 568                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
 569
 570         /* Initialize gcinode cache */
 571         err = nilfs_init_gccache(nilfs);
 572         if (err)
 573                 goto failed_sbh;
 574
 575         set_nilfs_init(nilfs);
 576         err = 0;
 577  out:
 578         up_write(&nilfs->ns_sem);
 579         return err;
 580
 581  failed_sbh:
 582         nilfs_release_super_block(nilfs);
 583         goto out;
 584 }
 585
 586 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 587 {
 588         struct inode *dat = nilfs_dat_inode(nilfs);
 589         unsigned long ncleansegs;
 590         int err;
 591
 592         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 593         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
 594         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 595         if (likely(!err))
 596                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 597         return err;
 598 }
 599
 600 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 601 {
 602         struct inode *sufile = nilfs->ns_sufile;
 603         unsigned long ncleansegs, nincsegs;
 604         int ret;
 605
 606         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
 607         if (likely(!ret)) {
 608                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 609                         nilfs->ns_blocks_per_segment + 1;
 610                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
 611                         ret++;
 612         }
 613         return ret;
 614 }
 615
 616 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 617                                 int snapshot_mount)
 618 {
 619         struct nilfs_sb_info *sbi;
 620         int ret = 0;
 621
 622         down_read(&nilfs->ns_sem);
 623         if (cno == 0 || cno > nilfs->ns_cno)
 624                 goto out_unlock;
 625
 626         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 627                 if (sbi->s_snapshot_cno == cno &&
 628                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 629                                         /* exclude read-only mounts */
 630                         ret++;
 631                         break;
 632                 }
 633         }
 634         /* for protecting recent checkpoints */
 635         if (cno >= nilfs_last_cno(nilfs))
 636                 ret++;
 637
 638  out_unlock:
 639         up_read(&nilfs->ns_sem);
 640         return ret;
 641 }