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
  39 static LIST_HEAD(nilfs_objects);
  40 static DEFINE_SPINLOCK(nilfs_lock);
  41
  42 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  43                             sector_t start_blocknr, u64 seq, __u64 cno)
  44 {
  45         spin_lock(&nilfs->ns_last_segment_lock);
  46         nilfs->ns_last_pseg = start_blocknr;
  47         nilfs->ns_last_seq = seq;
  48         nilfs->ns_last_cno = cno;
  49         spin_unlock(&nilfs->ns_last_segment_lock);
  50 }
  51
  52 /**
  53  * alloc_nilfs - allocate the_nilfs structure
  54  * @bdev: block device to which the_nilfs is related
  55  *
  56  * alloc_nilfs() allocates memory for the_nilfs and
  57  * initializes its reference count and locks.
  58  *
  59  * Return Value: On success, pointer to the_nilfs is returned.
  60  * On error, NULL is returned.
  61  */
  62 static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  63 {
  64         struct the_nilfs *nilfs;
  65
  66         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  67         if (!nilfs)
  68                 return NULL;
  69
  70         nilfs->ns_bdev = bdev;
  71         atomic_set(&nilfs->ns_count, 1);
  72         atomic_set(&nilfs->ns_writer_refcount, -1);
  73         atomic_set(&nilfs->ns_ndirtyblks, 0);
  74         init_rwsem(&nilfs->ns_sem);
  75         init_rwsem(&nilfs->ns_super_sem);
  76         mutex_init(&nilfs->ns_mount_mutex);
  77         mutex_init(&nilfs->ns_writer_mutex);
  78         INIT_LIST_HEAD(&nilfs->ns_list);
  79         INIT_LIST_HEAD(&nilfs->ns_supers);
  80         spin_lock_init(&nilfs->ns_last_segment_lock);
  81         nilfs->ns_gc_inodes_h = NULL;
  82         init_rwsem(&nilfs->ns_segctor_sem);
  83
  84         return nilfs;
  85 }
  86
  87 /**
  88  * find_or_create_nilfs - find or create nilfs object
  89  * @bdev: block device to which the_nilfs is related
  90  *
  91  * find_nilfs() looks up an existent nilfs object created on the
  92  * device and gets the reference count of the object.  If no nilfs object
  93  * is found on the device, a new nilfs object is allocated.
  94  *
  95  * Return Value: On success, pointer to the nilfs object is returned.
  96  * On error, NULL is returned.
  97  */
  98 struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)
  99 {
 100         struct the_nilfs *nilfs, *new = NULL;
 101
 102  retry:
 103         spin_lock(&nilfs_lock);
 104         list_for_each_entry(nilfs, &nilfs_objects, ns_list) {
 105                 if (nilfs->ns_bdev == bdev) {
 106                         get_nilfs(nilfs);
 107                         spin_unlock(&nilfs_lock);
 108                         if (new)
 109                                 put_nilfs(new);
 110                         return nilfs; /* existing object */
 111                 }
 112         }
 113         if (new) {
 114                 list_add_tail(&new->ns_list, &nilfs_objects);
 115                 spin_unlock(&nilfs_lock);
 116                 return new; /* new object */
 117         }
 118         spin_unlock(&nilfs_lock);
 119
 120         new = alloc_nilfs(bdev);
 121         if (new)
 122                 goto retry;
 123         return NULL; /* insufficient memory */
 124 }
 125
 126 /**
 127  * put_nilfs - release a reference to the_nilfs
 128  * @nilfs: the_nilfs structure to be released
 129  *
 130  * put_nilfs() decrements a reference counter of the_nilfs.
 131  * If the reference count reaches zero, the_nilfs is freed.
 132  */
 133 void put_nilfs(struct the_nilfs *nilfs)
 134 {
 135         spin_lock(&nilfs_lock);
 136         if (!atomic_dec_and_test(&nilfs->ns_count)) {
 137                 spin_unlock(&nilfs_lock);
 138                 return;
 139         }
 140         list_del_init(&nilfs->ns_list);
 141         spin_unlock(&nilfs_lock);
 142
 143         /*
 144          * Increment of ns_count never occurs below because the caller
 145          * of get_nilfs() holds at least one reference to the_nilfs.
 146          * Thus its exclusion control is not required here.
 147          */
 148
 149         might_sleep();
 150         if (nilfs_loaded(nilfs)) {
 151                 nilfs_mdt_clear(nilfs->ns_sufile);
 152                 nilfs_mdt_destroy(nilfs->ns_sufile);
 153                 nilfs_mdt_clear(nilfs->ns_cpfile);
 154                 nilfs_mdt_destroy(nilfs->ns_cpfile);
 155                 nilfs_mdt_clear(nilfs->ns_dat);
 156                 nilfs_mdt_destroy(nilfs->ns_dat);
 157                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
 158                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 159         }
 160         if (nilfs_init(nilfs)) {
 161                 nilfs_destroy_gccache(nilfs);
 162                 brelse(nilfs->ns_sbh[0]);
 163                 brelse(nilfs->ns_sbh[1]);
 164         }
 165         kfree(nilfs);
 166 }
 167
 168 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 169                                  struct nilfs_sb_info *sbi, sector_t sr_block)
 170 {
 171         static struct lock_class_key dat_lock_key;
 172         struct buffer_head *bh_sr;
 173         struct nilfs_super_root *raw_sr;
 174         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 175         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 176         unsigned inode_size;
 177         int err;
 178
 179         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
 180         if (unlikely(err))
 181                 return err;
 182
 183         down_read(&nilfs->ns_sem);
 184         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 185         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 186         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 187         up_read(&nilfs->ns_sem);
 188
 189         inode_size = nilfs->ns_inode_size;
 190
 191         err = -ENOMEM;
 192         nilfs->ns_dat = nilfs_mdt_new(
 193                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 194         if (unlikely(!nilfs->ns_dat))
 195                 goto failed;
 196
 197         nilfs->ns_gc_dat = nilfs_mdt_new(
 198                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
 199         if (unlikely(!nilfs->ns_gc_dat))
 200                 goto failed_dat;
 201
 202         nilfs->ns_cpfile = nilfs_mdt_new(
 203                 nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
 204         if (unlikely(!nilfs->ns_cpfile))
 205                 goto failed_gc_dat;
 206
 207         nilfs->ns_sufile = nilfs_mdt_new(
 208                 nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
 209         if (unlikely(!nilfs->ns_sufile))
 210                 goto failed_cpfile;
 211
 212         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
 213         if (unlikely(err))
 214                 goto failed_sufile;
 215
 216         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
 217         if (unlikely(err))
 218                 goto failed_sufile;
 219
 220         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
 221         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
 222
 223         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 224         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
 225                                  sizeof(struct nilfs_cpfile_header));
 226         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
 227                                  sizeof(struct nilfs_sufile_header));
 228
 229         err = nilfs_mdt_read_inode_direct(
 230                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
 231         if (unlikely(err))
 232                 goto failed_sufile;
 233
 234         err = nilfs_mdt_read_inode_direct(
 235                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
 236         if (unlikely(err))
 237                 goto failed_sufile;
 238
 239         err = nilfs_mdt_read_inode_direct(
 240                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
 241         if (unlikely(err))
 242                 goto failed_sufile;
 243
 244         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 245         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 246
 247  failed:
 248         brelse(bh_sr);
 249         return err;
 250
 251  failed_sufile:
 252         nilfs_mdt_destroy(nilfs->ns_sufile);
 253
 254  failed_cpfile:
 255         nilfs_mdt_destroy(nilfs->ns_cpfile);
 256
 257  failed_gc_dat:
 258         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 259
 260  failed_dat:
 261         nilfs_mdt_destroy(nilfs->ns_dat);
 262         goto failed;
 263 }
 264
 265 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 266 {
 267         memset(ri, 0, sizeof(*ri));
 268         INIT_LIST_HEAD(&ri->ri_used_segments);
 269 }
 270
 271 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 272 {
 273         nilfs_dispose_segment_list(&ri->ri_used_segments);
 274 }
 275
 276 /**
 277  * load_nilfs - load and recover the nilfs
 278  * @nilfs: the_nilfs structure to be released
 279  * @sbi: nilfs_sb_info used to recover past segment
 280  *
 281  * load_nilfs() searches and load the latest super root,
 282  * attaches the last segment, and does recovery if needed.
 283  * The caller must call this exclusively for simultaneous mounts.
 284  */
 285 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 286 {
 287         struct nilfs_recovery_info ri;
 288         unsigned int s_flags = sbi->s_super->s_flags;
 289         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 290         unsigned valid_fs;
 291         int err = 0;
 292
 293         nilfs_init_recovery_info(&ri);
 294
 295         down_write(&nilfs->ns_sem);
 296         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 297         up_write(&nilfs->ns_sem);
 298
 299         if (!valid_fs && (s_flags & MS_RDONLY)) {
 300                 printk(KERN_INFO "NILFS: INFO: recovery "
 301                        "required for readonly filesystem.\n");
 302                 if (really_read_only) {
 303                         printk(KERN_ERR "NILFS: write access "
 304                                "unavailable, cannot proceed.\n");
 305                         err = -EROFS;
 306                         goto failed;
 307                 }
 308                 printk(KERN_INFO "NILFS: write access will "
 309                        "be enabled during recovery.\n");
 310                 sbi->s_super->s_flags &= ~MS_RDONLY;
 311         }
 312
 313         err = nilfs_search_super_root(nilfs, sbi, &ri);
 314         if (unlikely(err)) {
 315                 printk(KERN_ERR "NILFS: error searching super root.\n");
 316                 goto failed;
 317         }
 318
 319         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
 320         if (unlikely(err)) {
 321                 printk(KERN_ERR "NILFS: error loading super root.\n");
 322                 goto failed;
 323         }
 324
 325         if (!valid_fs) {
 326                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
 327                 if (unlikely(err)) {
 328                         nilfs_mdt_destroy(nilfs->ns_cpfile);
 329                         nilfs_mdt_destroy(nilfs->ns_sufile);
 330                         nilfs_mdt_destroy(nilfs->ns_dat);
 331                         goto failed;
 332                 }
 333                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
 334                         sbi->s_super->s_dirt = 1;
 335         }
 336
 337         set_nilfs_loaded(nilfs);
 338
 339  failed:
 340         nilfs_clear_recovery_info(&ri);
 341         sbi->s_super->s_flags = s_flags;
 342         return err;
 343 }
 344
 345 static unsigned long long nilfs_max_size(unsigned int blkbits)
 346 {
 347         unsigned int max_bits;
 348         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 349
 350         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 351         if (max_bits < 64)
 352                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 353         return res;
 354 }
 355
 356 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 357                                    struct nilfs_super_block *sbp)
 358 {
 359         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 360                 printk(KERN_ERR "NILFS: revision mismatch "
 361                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 362                        "Please check the version of mkfs.nilfs.\n",
 363                        le32_to_cpu(sbp->s_rev_level),
 364                        le16_to_cpu(sbp->s_minor_rev_level),
 365                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 366                 return -EINVAL;
 367         }
 368         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 369         if (nilfs->ns_sbsize > BLOCK_SIZE)
 370                 return -EINVAL;
 371
 372         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 373         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 374
 375         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 376         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 377                 printk(KERN_ERR "NILFS: too short segment. \n");
 378                 return -EINVAL;
 379         }
 380
 381         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 382         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 383         nilfs->ns_r_segments_percentage =
 384                 le32_to_cpu(sbp->s_r_segments_percentage);
 385         nilfs->ns_nrsvsegs =
 386                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 387                       DIV_ROUND_UP(nilfs->ns_nsegments *
 388                                    nilfs->ns_r_segments_percentage, 100));
 389         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 390         return 0;
 391 }
 392
 393 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 394 {
 395         static unsigned char sum[4];
 396         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 397         size_t bytes;
 398         u32 crc;
 399
 400         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 401                 return 0;
 402         bytes = le16_to_cpu(sbp->s_bytes);
 403         if (bytes > BLOCK_SIZE)
 404                 return 0;
 405         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 406                        sumoff);
 407         crc = crc32_le(crc, sum, 4);
 408         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 409                        bytes - sumoff - 4);
 410         return crc == le32_to_cpu(sbp->s_sum);
 411 }
 412
 413 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 414 {
 415         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 416                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 417                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 418 }
 419
 420 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 421 {
 422         int i;
 423
 424         for (i = 0; i < 2; i++) {
 425                 if (nilfs->ns_sbp[i]) {
 426                         brelse(nilfs->ns_sbh[i]);
 427                         nilfs->ns_sbh[i] = NULL;
 428                         nilfs->ns_sbp[i] = NULL;
 429                 }
 430         }
 431 }
 432
 433 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 434 {
 435         brelse(nilfs->ns_sbh[0]);
 436         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 437         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 438         nilfs->ns_sbh[1] = NULL;
 439         nilfs->ns_sbp[1] = NULL;
 440 }
 441
 442 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 443 {
 444         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 445         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 446
 447         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 448         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 449         nilfs->ns_sbh[1] = tsbh;
 450         nilfs->ns_sbp[1] = tsbp;
 451 }
 452
 453 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 454                                   struct super_block *sb, int blocksize,
 455                                   struct nilfs_super_block **sbpp)
 456 {
 457         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 458         struct buffer_head **sbh = nilfs->ns_sbh;
 459         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 460         int valid[2], swp = 0;
 461
 462         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 463                                         &sbh[0]);
 464         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 465
 466         if (!sbp[0]) {
 467                 if (!sbp[1]) {
 468                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 469                         return -EIO;
 470                 }
 471                 printk(KERN_WARNING
 472                        "NILFS warning: unable to read primary superblock\n");
 473         } else if (!sbp[1])
 474                 printk(KERN_WARNING
 475                        "NILFS warning: unable to read secondary superblock\n");
 476
 477         valid[0] = nilfs_valid_sb(sbp[0]);
 478         valid[1] = nilfs_valid_sb(sbp[1]);
 479         swp = valid[1] &&
 480                 (!valid[0] ||
 481                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
 482
 483         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 484                 brelse(sbh[1]);
 485                 sbh[1] = NULL;
 486                 sbp[1] = NULL;
 487                 swp = 0;
 488         }
 489         if (!valid[swp]) {
 490                 nilfs_release_super_block(nilfs);
 491                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 492                        sb->s_id);
 493                 return -EINVAL;
 494         }
 495
 496         if (swp) {
 497                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 498                        "using spare superblock.\n");
 499                 nilfs_swap_super_block(nilfs);
 500         }
 501
 502         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
 503         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
 504         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 505         *sbpp = sbp[0];
 506         return 0;
 507 }
 508
 509 /**
 510  * init_nilfs - initialize a NILFS instance.
 511  * @nilfs: the_nilfs structure
 512  * @sbi: nilfs_sb_info
 513  * @sb: super block
 514  * @data: mount options
 515  *
 516  * init_nilfs() performs common initialization per block device (e.g.
 517  * reading the super block, getting disk layout information, initializing
 518  * shared fields in the_nilfs). It takes on some portion of the jobs
 519  * typically done by a fill_super() routine. This division arises from
 520  * the nature that multiple NILFS instances may be simultaneously
 521  * mounted on a device.
 522  * For multiple mounts on the same device, only the first mount
 523  * invokes these tasks.
 524  *
 525  * Return Value: On success, 0 is returned. On error, a negative error
 526  * code is returned.
 527  */
 528 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 529 {
 530         struct super_block *sb = sbi->s_super;
 531         struct nilfs_super_block *sbp;
 532         struct backing_dev_info *bdi;
 533         int blocksize;
 534         int err;
 535
 536         down_write(&nilfs->ns_sem);
 537         if (nilfs_init(nilfs)) {
 538                 /* Load values from existing the_nilfs */
 539                 sbp = nilfs->ns_sbp[0];
 540                 err = nilfs_store_magic_and_option(sb, sbp, data);
 541                 if (err)
 542                         goto out;
 543
 544                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 545                 if (sb->s_blocksize != blocksize &&
 546                     !sb_set_blocksize(sb, blocksize)) {
 547                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 548                                blocksize);
 549                         err = -EINVAL;
 550                 }
 551                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 552                 goto out;
 553         }
 554
 555         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 556         if (!blocksize) {
 557                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 558                 err = -EINVAL;
 559                 goto out;
 560         }
 561         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 562         if (err)
 563                 goto out;
 564
 565         err = nilfs_store_magic_and_option(sb, sbp, data);
 566         if (err)
 567                 goto failed_sbh;
 568
 569         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 570         if (sb->s_blocksize != blocksize) {
 571                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 572
 573                 if (blocksize < hw_blocksize) {
 574                         printk(KERN_ERR
 575                                "NILFS: blocksize %d too small for device "
 576                                "(sector-size = %d).\n",
 577                                blocksize, hw_blocksize);
 578                         err = -EINVAL;
 579                         goto failed_sbh;
 580                 }
 581                 nilfs_release_super_block(nilfs);
 582                 sb_set_blocksize(sb, blocksize);
 583
 584                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 585                 if (err)
 586                         goto out;
 587                         /* not failed_sbh; sbh is released automatically
 588                            when reloading fails. */
 589         }
 590         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 591
 592         err = nilfs_store_disk_layout(nilfs, sbp);
 593         if (err)
 594                 goto failed_sbh;
 595
 596         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 597
 598         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 599
 600         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
 601         if (!bdi)
 602                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 603         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 604
 605         /* Finding last segment */
 606         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 607         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 608         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 609
 610         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 611         nilfs->ns_segnum =
 612                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 613         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 614         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 615                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 616                 err = -EINVAL;
 617                 goto failed_sbh;
 618         }
 619         /* Dummy values  */
 620         nilfs->ns_free_segments_count =
 621                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
 622
 623         /* Initialize gcinode cache */
 624         err = nilfs_init_gccache(nilfs);
 625         if (err)
 626                 goto failed_sbh;
 627
 628         set_nilfs_init(nilfs);
 629         err = 0;
 630  out:
 631         up_write(&nilfs->ns_sem);
 632         return err;
 633
 634  failed_sbh:
 635         nilfs_release_super_block(nilfs);
 636         goto out;
 637 }
 638
 639 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 640 {
 641         struct inode *dat = nilfs_dat_inode(nilfs);
 642         unsigned long ncleansegs;
 643         int err;
 644
 645         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 646         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
 647         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 648         if (likely(!err))
 649                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 650         return err;
 651 }
 652
 653 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 654 {
 655         struct inode *sufile = nilfs->ns_sufile;
 656         unsigned long ncleansegs, nincsegs;
 657         int ret;
 658
 659         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
 660         if (likely(!ret)) {
 661                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 662                         nilfs->ns_blocks_per_segment + 1;
 663                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
 664                         ret++;
 665         }
 666         return ret;
 667 }
 668
 669 /**
 670  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
 671  * @nilfs: nilfs object
 672  * @rw_mount: mount type (non-zero value for read/write mount)
 673  * @cno: checkpoint number (zero for read-only mount)
 674  *
 675  * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
 676  * @rw_mount and @cno (in case of snapshots) matched.  If no instance
 677  * was found, NULL is returned.  Although the super block instance can
 678  * be unmounted after this function returns, the nilfs_sb_info struct
 679  * is kept on memory until nilfs_put_sbinfo() is called.
 680  */
 681 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
 682                                         int rw_mount, __u64 cno)
 683 {
 684         struct nilfs_sb_info *sbi;
 685
 686         down_read(&nilfs->ns_super_sem);
 687         /*
 688          * The SNAPSHOT flag and sb->s_flags are supposed to be
 689          * protected with nilfs->ns_super_sem.
 690          */
 691         sbi = nilfs->ns_current;
 692         if (rw_mount) {
 693                 if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
 694                         goto found; /* read/write mount */
 695                 else
 696                         goto out;
 697         } else if (cno == 0) {
 698                 if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
 699                         goto found; /* read-only mount */
 700                 else
 701                         goto out;
 702         }
 703
 704         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 705                 if (nilfs_test_opt(sbi, SNAPSHOT) &&
 706                     sbi->s_snapshot_cno == cno)
 707                         goto found; /* snapshot mount */
 708         }
 709  out:
 710         up_read(&nilfs->ns_super_sem);
 711         return NULL;
 712
 713  found:
 714         atomic_inc(&sbi->s_count);
 715         up_read(&nilfs->ns_super_sem);
 716         return sbi;
 717 }
 718
 719 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 720                                 int snapshot_mount)
 721 {
 722         struct nilfs_sb_info *sbi;
 723         int ret = 0;
 724
 725         down_read(&nilfs->ns_super_sem);
 726         if (cno == 0 || cno > nilfs->ns_cno)
 727                 goto out_unlock;
 728
 729         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 730                 if (sbi->s_snapshot_cno == cno &&
 731                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 732                                         /* exclude read-only mounts */
 733                         ret++;
 734                         break;
 735                 }
 736         }
 737         /* for protecting recent checkpoints */
 738         if (cno >= nilfs_last_cno(nilfs))
 739                 ret++;
 740
 741  out_unlock:
 742         up_read(&nilfs->ns_super_sem);
 743         return ret;
 744 }