git.oblomov.eu Git - linux-2.6/blob - 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         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         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 167         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
 168                                  sizeof(struct nilfs_cpfile_header));
 169         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
 170                                  sizeof(struct nilfs_sufile_header));
 171
 172         err = nilfs_mdt_read_inode_direct(
 173                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
 174         if (unlikely(err))
 175                 goto failed_sufile;
 176
 177         err = nilfs_mdt_read_inode_direct(
 178                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
 179         if (unlikely(err))
 180                 goto failed_sufile;
 181
 182         err = nilfs_mdt_read_inode_direct(
 183                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
 184         if (unlikely(err))
 185                 goto failed_sufile;
 186
 187         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 188         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 189
 190  failed:
 191         brelse(bh_sr);
 192         return err;
 193
 194  failed_sufile:
 195         nilfs_mdt_destroy(nilfs->ns_sufile);
 196
 197  failed_cpfile:
 198         nilfs_mdt_destroy(nilfs->ns_cpfile);
 199
 200  failed_gc_dat:
 201         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 202
 203  failed_dat:
 204         nilfs_mdt_destroy(nilfs->ns_dat);
 205         goto failed;
 206 }
 207
 208 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 209 {
 210         memset(ri, 0, sizeof(*ri));
 211         INIT_LIST_HEAD(&ri->ri_used_segments);
 212 }
 213
 214 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 215 {
 216         nilfs_dispose_segment_list(&ri->ri_used_segments);
 217 }
 218
 219 /**
 220  * load_nilfs - load and recover the nilfs
 221  * @nilfs: the_nilfs structure to be released
 222  * @sbi: nilfs_sb_info used to recover past segment
 223  *
 224  * load_nilfs() searches and load the latest super root,
 225  * attaches the last segment, and does recovery if needed.
 226  * The caller must call this exclusively for simultaneous mounts.
 227  */
 228 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 229 {
 230         struct nilfs_recovery_info ri;
 231         unsigned int s_flags = sbi->s_super->s_flags;
 232         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 233         unsigned valid_fs;
 234         int err = 0;
 235
 236         nilfs_init_recovery_info(&ri);
 237
 238         down_write(&nilfs->ns_sem);
 239         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 240         up_write(&nilfs->ns_sem);
 241
 242         if (!valid_fs && (s_flags & MS_RDONLY)) {
 243                 printk(KERN_INFO "NILFS: INFO: recovery "
 244                        "required for readonly filesystem.\n");
 245                 if (really_read_only) {
 246                         printk(KERN_ERR "NILFS: write access "
 247                                "unavailable, cannot proceed.\n");
 248                         err = -EROFS;
 249                         goto failed;
 250                 }
 251                 printk(KERN_INFO "NILFS: write access will "
 252                        "be enabled during recovery.\n");
 253                 sbi->s_super->s_flags &= ~MS_RDONLY;
 254         }
 255
 256         err = nilfs_search_super_root(nilfs, sbi, &ri);
 257         if (unlikely(err)) {
 258                 printk(KERN_ERR "NILFS: error searching super root.\n");
 259                 goto failed;
 260         }
 261
 262         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
 263         if (unlikely(err)) {
 264                 printk(KERN_ERR "NILFS: error loading super root.\n");
 265                 goto failed;
 266         }
 267
 268         if (!valid_fs) {
 269                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
 270                 if (unlikely(err)) {
 271                         nilfs_mdt_destroy(nilfs->ns_cpfile);
 272                         nilfs_mdt_destroy(nilfs->ns_sufile);
 273                         nilfs_mdt_destroy(nilfs->ns_dat);
 274                         goto failed;
 275                 }
 276                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
 277                         sbi->s_super->s_dirt = 1;
 278         }
 279
 280         set_nilfs_loaded(nilfs);
 281
 282  failed:
 283         nilfs_clear_recovery_info(&ri);
 284         sbi->s_super->s_flags = s_flags;
 285         return err;
 286 }
 287
 288 static unsigned long long nilfs_max_size(unsigned int blkbits)
 289 {
 290         unsigned int max_bits;
 291         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 292
 293         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 294         if (max_bits < 64)
 295                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 296         return res;
 297 }
 298
 299 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 300                                    struct nilfs_super_block *sbp)
 301 {
 302         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 303                 printk(KERN_ERR "NILFS: revision mismatch "
 304                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 305                        "Please check the version of mkfs.nilfs.\n",
 306                        le32_to_cpu(sbp->s_rev_level),
 307                        le16_to_cpu(sbp->s_minor_rev_level),
 308                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 309                 return -EINVAL;
 310         }
 311         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 312         if (nilfs->ns_sbsize > BLOCK_SIZE)
 313                 return -EINVAL;
 314
 315         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 316         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 317
 318         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 319         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 320                 printk(KERN_ERR "NILFS: too short segment. \n");
 321                 return -EINVAL;
 322         }
 323
 324         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 325         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 326         nilfs->ns_r_segments_percentage =
 327                 le32_to_cpu(sbp->s_r_segments_percentage);
 328         nilfs->ns_nrsvsegs =
 329                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 330                       DIV_ROUND_UP(nilfs->ns_nsegments *
 331                                    nilfs->ns_r_segments_percentage, 100));
 332         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 333         return 0;
 334 }
 335
 336 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 337 {
 338         static unsigned char sum[4];
 339         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 340         size_t bytes;
 341         u32 crc;
 342
 343         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 344                 return 0;
 345         bytes = le16_to_cpu(sbp->s_bytes);
 346         if (bytes > BLOCK_SIZE)
 347                 return 0;
 348         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 349                        sumoff);
 350         crc = crc32_le(crc, sum, 4);
 351         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 352                        bytes - sumoff - 4);
 353         return crc == le32_to_cpu(sbp->s_sum);
 354 }
 355
 356 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 357 {
 358         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 359                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 360                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 361 }
 362
 363 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 364 {
 365         int i;
 366
 367         for (i = 0; i < 2; i++) {
 368                 if (nilfs->ns_sbp[i]) {
 369                         brelse(nilfs->ns_sbh[i]);
 370                         nilfs->ns_sbh[i] = NULL;
 371                         nilfs->ns_sbp[i] = NULL;
 372                 }
 373         }
 374 }
 375
 376 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 377 {
 378         brelse(nilfs->ns_sbh[0]);
 379         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 380         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 381         nilfs->ns_sbh[1] = NULL;
 382         nilfs->ns_sbp[1] = NULL;
 383 }
 384
 385 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 386 {
 387         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 388         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 389
 390         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 391         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 392         nilfs->ns_sbh[1] = tsbh;
 393         nilfs->ns_sbp[1] = tsbp;
 394 }
 395
 396 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 397                                   struct super_block *sb, int blocksize,
 398                                   struct nilfs_super_block **sbpp)
 399 {
 400         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 401         struct buffer_head **sbh = nilfs->ns_sbh;
 402         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 403         int valid[2], swp = 0;
 404
 405         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 406                                         &sbh[0]);
 407         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 408
 409         if (!sbp[0]) {
 410                 if (!sbp[1]) {
 411                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 412                         return -EIO;
 413                 }
 414                 printk(KERN_WARNING
 415                        "NILFS warning: unable to read primary superblock\n");
 416         } else if (!sbp[1])
 417                 printk(KERN_WARNING
 418                        "NILFS warning: unable to read secondary superblock\n");
 419
 420         valid[0] = nilfs_valid_sb(sbp[0]);
 421         valid[1] = nilfs_valid_sb(sbp[1]);
 422         swp = valid[1] &&
 423                 (!valid[0] ||
 424                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
 425
 426         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 427                 brelse(sbh[1]);
 428                 sbh[1] = NULL;
 429                 sbp[1] = NULL;
 430                 swp = 0;
 431         }
 432         if (!valid[swp]) {
 433                 nilfs_release_super_block(nilfs);
 434                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 435                        sb->s_id);
 436                 return -EINVAL;
 437         }
 438
 439         if (swp) {
 440                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 441                        "using spare superblock.\n");
 442                 nilfs_swap_super_block(nilfs);
 443         }
 444
 445         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
 446         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
 447         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 448         *sbpp = sbp[0];
 449         return 0;
 450 }
 451
 452 /**
 453  * init_nilfs - initialize a NILFS instance.
 454  * @nilfs: the_nilfs structure
 455  * @sbi: nilfs_sb_info
 456  * @sb: super block
 457  * @data: mount options
 458  *
 459  * init_nilfs() performs common initialization per block device (e.g.
 460  * reading the super block, getting disk layout information, initializing
 461  * shared fields in the_nilfs). It takes on some portion of the jobs
 462  * typically done by a fill_super() routine. This division arises from
 463  * the nature that multiple NILFS instances may be simultaneously
 464  * mounted on a device.
 465  * For multiple mounts on the same device, only the first mount
 466  * invokes these tasks.
 467  *
 468  * Return Value: On success, 0 is returned. On error, a negative error
 469  * code is returned.
 470  */
 471 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 472 {
 473         struct super_block *sb = sbi->s_super;
 474         struct nilfs_super_block *sbp;
 475         struct backing_dev_info *bdi;
 476         int blocksize;
 477         int err;
 478
 479         down_write(&nilfs->ns_sem);
 480         if (nilfs_init(nilfs)) {
 481                 /* Load values from existing the_nilfs */
 482                 sbp = nilfs->ns_sbp[0];
 483                 err = nilfs_store_magic_and_option(sb, sbp, data);
 484                 if (err)
 485                         goto out;
 486
 487                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 488                 if (sb->s_blocksize != blocksize &&
 489                     !sb_set_blocksize(sb, blocksize)) {
 490                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 491                                blocksize);
 492                         err = -EINVAL;
 493                 }
 494                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 495                 goto out;
 496         }
 497
 498         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 499         if (!blocksize) {
 500                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 501                 err = -EINVAL;
 502                 goto out;
 503         }
 504         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 505         if (err)
 506                 goto out;
 507
 508         err = nilfs_store_magic_and_option(sb, sbp, data);
 509         if (err)
 510                 goto failed_sbh;
 511
 512         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 513         if (sb->s_blocksize != blocksize) {
 514                 int hw_blocksize = bdev_hardsect_size(sb->s_bdev);
 515
 516                 if (blocksize < hw_blocksize) {
 517                         printk(KERN_ERR
 518                                "NILFS: blocksize %d too small for device "
 519                                "(sector-size = %d).\n",
 520                                blocksize, hw_blocksize);
 521                         err = -EINVAL;
 522                         goto failed_sbh;
 523                 }
 524                 nilfs_release_super_block(nilfs);
 525                 sb_set_blocksize(sb, blocksize);
 526
 527                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 528                 if (err)
 529                         goto out;
 530                         /* not failed_sbh; sbh is released automatically
 531                            when reloading fails. */
 532         }
 533         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 534
 535         err = nilfs_store_disk_layout(nilfs, sbp);
 536         if (err)
 537                 goto failed_sbh;
 538
 539         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 540
 541         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 542
 543         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
 544         if (!bdi)
 545                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 546         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 547
 548         /* Finding last segment */
 549         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 550         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 551         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 552
 553         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 554         nilfs->ns_segnum =
 555                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 556         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 557         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 558                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 559                 err = -EINVAL;
 560                 goto failed_sbh;
 561         }
 562         /* Dummy values  */
 563         nilfs->ns_free_segments_count =
 564                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
 565
 566         /* Initialize gcinode cache */
 567         err = nilfs_init_gccache(nilfs);
 568         if (err)
 569                 goto failed_sbh;
 570
 571         set_nilfs_init(nilfs);
 572         err = 0;
 573  out:
 574         up_write(&nilfs->ns_sem);
 575         return err;
 576
 577  failed_sbh:
 578         nilfs_release_super_block(nilfs);
 579         goto out;
 580 }
 581
 582 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 583 {
 584         struct inode *dat = nilfs_dat_inode(nilfs);
 585         unsigned long ncleansegs;
 586         int err;
 587
 588         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 589         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
 590         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 591         if (likely(!err))
 592                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 593         return err;
 594 }
 595
 596 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 597 {
 598         struct inode *sufile = nilfs->ns_sufile;
 599         unsigned long ncleansegs, nincsegs;
 600         int ret;
 601
 602         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
 603         if (likely(!ret)) {
 604                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 605                         nilfs->ns_blocks_per_segment + 1;
 606                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
 607                         ret++;
 608         }
 609         return ret;
 610 }
 611
 612 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 613                                 int snapshot_mount)
 614 {
 615         struct nilfs_sb_info *sbi;
 616         int ret = 0;
 617
 618         down_read(&nilfs->ns_sem);
 619         if (cno == 0 || cno > nilfs->ns_cno)
 620                 goto out_unlock;
 621
 622         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 623                 if (sbi->s_snapshot_cno == cno &&
 624                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 625                                         /* exclude read-only mounts */
 626                         ret++;
 627                         break;
 628                 }
 629         }
 630         /* for protecting recent checkpoints */
 631         if (cno >= nilfs_last_cno(nilfs))
 632                 ret++;
 633
 634  out_unlock:
 635         up_read(&nilfs->ns_sem);
 636         return ret;
 637 }