SAFE public projects git trees. - safe/jmp/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 "segbuf.h"
  36
  37
  38 static LIST_HEAD(nilfs_objects);
  39 static DEFINE_SPINLOCK(nilfs_lock);
  40
  41 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  42                             sector_t start_blocknr, u64 seq, __u64 cno)
  43 {
  44         spin_lock(&nilfs->ns_last_segment_lock);
  45         nilfs->ns_last_pseg = start_blocknr;
  46         nilfs->ns_last_seq = seq;
  47         nilfs->ns_last_cno = cno;
  48         spin_unlock(&nilfs->ns_last_segment_lock);
  49 }
  50
  51 /**
  52  * alloc_nilfs - allocate the_nilfs structure
  53  * @bdev: block device to which the_nilfs is related
  54  *
  55  * alloc_nilfs() allocates memory for the_nilfs and
  56  * initializes its reference count and locks.
  57  *
  58  * Return Value: On success, pointer to the_nilfs is returned.
  59  * On error, NULL is returned.
  60  */
  61 static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  62 {
  63         struct the_nilfs *nilfs;
  64
  65         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  66         if (!nilfs)
  67                 return NULL;
  68
  69         nilfs->ns_bdev = bdev;
  70         atomic_set(&nilfs->ns_count, 1);
  71         atomic_set(&nilfs->ns_ndirtyblks, 0);
  72         init_rwsem(&nilfs->ns_sem);
  73         init_rwsem(&nilfs->ns_super_sem);
  74         mutex_init(&nilfs->ns_mount_mutex);
  75         init_rwsem(&nilfs->ns_writer_sem);
  76         INIT_LIST_HEAD(&nilfs->ns_list);
  77         INIT_LIST_HEAD(&nilfs->ns_supers);
  78         spin_lock_init(&nilfs->ns_last_segment_lock);
  79         nilfs->ns_gc_inodes_h = NULL;
  80         init_rwsem(&nilfs->ns_segctor_sem);
  81
  82         return nilfs;
  83 }
  84
  85 /**
  86  * find_or_create_nilfs - find or create nilfs object
  87  * @bdev: block device to which the_nilfs is related
  88  *
  89  * find_nilfs() looks up an existent nilfs object created on the
  90  * device and gets the reference count of the object.  If no nilfs object
  91  * is found on the device, a new nilfs object is allocated.
  92  *
  93  * Return Value: On success, pointer to the nilfs object is returned.
  94  * On error, NULL is returned.
  95  */
  96 struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)
  97 {
  98         struct the_nilfs *nilfs, *new = NULL;
  99
 100  retry:
 101         spin_lock(&nilfs_lock);
 102         list_for_each_entry(nilfs, &nilfs_objects, ns_list) {
 103                 if (nilfs->ns_bdev == bdev) {
 104                         get_nilfs(nilfs);
 105                         spin_unlock(&nilfs_lock);
 106                         if (new)
 107                                 put_nilfs(new);
 108                         return nilfs; /* existing object */
 109                 }
 110         }
 111         if (new) {
 112                 list_add_tail(&new->ns_list, &nilfs_objects);
 113                 spin_unlock(&nilfs_lock);
 114                 return new; /* new object */
 115         }
 116         spin_unlock(&nilfs_lock);
 117
 118         new = alloc_nilfs(bdev);
 119         if (new)
 120                 goto retry;
 121         return NULL; /* insufficient memory */
 122 }
 123
 124 /**
 125  * put_nilfs - release a reference to the_nilfs
 126  * @nilfs: the_nilfs structure to be released
 127  *
 128  * put_nilfs() decrements a reference counter of the_nilfs.
 129  * If the reference count reaches zero, the_nilfs is freed.
 130  */
 131 void put_nilfs(struct the_nilfs *nilfs)
 132 {
 133         spin_lock(&nilfs_lock);
 134         if (!atomic_dec_and_test(&nilfs->ns_count)) {
 135                 spin_unlock(&nilfs_lock);
 136                 return;
 137         }
 138         list_del_init(&nilfs->ns_list);
 139         spin_unlock(&nilfs_lock);
 140
 141         /*
 142          * Increment of ns_count never occurs below because the caller
 143          * of get_nilfs() holds at least one reference to the_nilfs.
 144          * Thus its exclusion control is not required here.
 145          */
 146
 147         might_sleep();
 148         if (nilfs_loaded(nilfs)) {
 149                 nilfs_mdt_clear(nilfs->ns_sufile);
 150                 nilfs_mdt_destroy(nilfs->ns_sufile);
 151                 nilfs_mdt_clear(nilfs->ns_cpfile);
 152                 nilfs_mdt_destroy(nilfs->ns_cpfile);
 153                 nilfs_mdt_clear(nilfs->ns_dat);
 154                 nilfs_mdt_destroy(nilfs->ns_dat);
 155                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
 156                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 157         }
 158         if (nilfs_init(nilfs)) {
 159                 nilfs_destroy_gccache(nilfs);
 160                 brelse(nilfs->ns_sbh[0]);
 161                 brelse(nilfs->ns_sbh[1]);
 162         }
 163         kfree(nilfs);
 164 }
 165
 166 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 167                                  struct nilfs_sb_info *sbi, sector_t sr_block)
 168 {
 169         static struct lock_class_key dat_lock_key;
 170         struct buffer_head *bh_sr;
 171         struct nilfs_super_root *raw_sr;
 172         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 173         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 174         unsigned inode_size;
 175         int err;
 176
 177         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
 178         if (unlikely(err))
 179                 return err;
 180
 181         down_read(&nilfs->ns_sem);
 182         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 183         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 184         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 185         up_read(&nilfs->ns_sem);
 186
 187         inode_size = nilfs->ns_inode_size;
 188
 189         err = -ENOMEM;
 190         nilfs->ns_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO);
 191         if (unlikely(!nilfs->ns_dat))
 192                 goto failed;
 193
 194         nilfs->ns_gc_dat = nilfs_mdt_new(nilfs, NULL, NILFS_DAT_INO);
 195         if (unlikely(!nilfs->ns_gc_dat))
 196                 goto failed_dat;
 197
 198         nilfs->ns_cpfile = nilfs_mdt_new(nilfs, NULL, NILFS_CPFILE_INO);
 199         if (unlikely(!nilfs->ns_cpfile))
 200                 goto failed_gc_dat;
 201
 202         nilfs->ns_sufile = nilfs_mdt_new(nilfs, NULL, NILFS_SUFILE_INO);
 203         if (unlikely(!nilfs->ns_sufile))
 204                 goto failed_cpfile;
 205
 206         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
 207         if (unlikely(err))
 208                 goto failed_sufile;
 209
 210         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
 211         if (unlikely(err))
 212                 goto failed_sufile;
 213
 214         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
 215         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
 216
 217         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 218         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
 219                                  sizeof(struct nilfs_cpfile_header));
 220         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
 221                                  sizeof(struct nilfs_sufile_header));
 222
 223         err = nilfs_mdt_read_inode_direct(
 224                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
 225         if (unlikely(err))
 226                 goto failed_sufile;
 227
 228         err = nilfs_mdt_read_inode_direct(
 229                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
 230         if (unlikely(err))
 231                 goto failed_sufile;
 232
 233         err = nilfs_mdt_read_inode_direct(
 234                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
 235         if (unlikely(err))
 236                 goto failed_sufile;
 237
 238         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 239         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 240
 241  failed:
 242         brelse(bh_sr);
 243         return err;
 244
 245  failed_sufile:
 246         nilfs_mdt_destroy(nilfs->ns_sufile);
 247
 248  failed_cpfile:
 249         nilfs_mdt_destroy(nilfs->ns_cpfile);
 250
 251  failed_gc_dat:
 252         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 253
 254  failed_dat:
 255         nilfs_mdt_destroy(nilfs->ns_dat);
 256         goto failed;
 257 }
 258
 259 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 260 {
 261         memset(ri, 0, sizeof(*ri));
 262         INIT_LIST_HEAD(&ri->ri_used_segments);
 263 }
 264
 265 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 266 {
 267         nilfs_dispose_segment_list(&ri->ri_used_segments);
 268 }
 269
 270 /**
 271  * load_nilfs - load and recover the nilfs
 272  * @nilfs: the_nilfs structure to be released
 273  * @sbi: nilfs_sb_info used to recover past segment
 274  *
 275  * load_nilfs() searches and load the latest super root,
 276  * attaches the last segment, and does recovery if needed.
 277  * The caller must call this exclusively for simultaneous mounts.
 278  */
 279 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 280 {
 281         struct nilfs_recovery_info ri;
 282         unsigned int s_flags = sbi->s_super->s_flags;
 283         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 284         unsigned valid_fs;
 285         int err = 0;
 286
 287         nilfs_init_recovery_info(&ri);
 288
 289         down_write(&nilfs->ns_sem);
 290         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 291         up_write(&nilfs->ns_sem);
 292
 293         if (!valid_fs && (s_flags & MS_RDONLY)) {
 294                 printk(KERN_INFO "NILFS: INFO: recovery "
 295                        "required for readonly filesystem.\n");
 296                 if (really_read_only) {
 297                         printk(KERN_ERR "NILFS: write access "
 298                                "unavailable, cannot proceed.\n");
 299                         err = -EROFS;
 300                         goto failed;
 301                 }
 302                 printk(KERN_INFO "NILFS: write access will "
 303                        "be enabled during recovery.\n");
 304                 sbi->s_super->s_flags &= ~MS_RDONLY;
 305         }
 306
 307         err = nilfs_search_super_root(nilfs, sbi, &ri);
 308         if (unlikely(err)) {
 309                 printk(KERN_ERR "NILFS: error searching super root.\n");
 310                 goto failed;
 311         }
 312
 313         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
 314         if (unlikely(err)) {
 315                 printk(KERN_ERR "NILFS: error loading super root.\n");
 316                 goto failed;
 317         }
 318
 319         if (!valid_fs) {
 320                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
 321                 if (unlikely(err)) {
 322                         nilfs_mdt_destroy(nilfs->ns_cpfile);
 323                         nilfs_mdt_destroy(nilfs->ns_sufile);
 324                         nilfs_mdt_destroy(nilfs->ns_dat);
 325                         goto failed;
 326                 }
 327                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
 328                         sbi->s_super->s_dirt = 1;
 329         }
 330
 331         set_nilfs_loaded(nilfs);
 332
 333  failed:
 334         nilfs_clear_recovery_info(&ri);
 335         sbi->s_super->s_flags = s_flags;
 336         return err;
 337 }
 338
 339 static unsigned long long nilfs_max_size(unsigned int blkbits)
 340 {
 341         unsigned int max_bits;
 342         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 343
 344         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 345         if (max_bits < 64)
 346                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 347         return res;
 348 }
 349
 350 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 351                                    struct nilfs_super_block *sbp)
 352 {
 353         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 354                 printk(KERN_ERR "NILFS: revision mismatch "
 355                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 356                        "Please check the version of mkfs.nilfs.\n",
 357                        le32_to_cpu(sbp->s_rev_level),
 358                        le16_to_cpu(sbp->s_minor_rev_level),
 359                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 360                 return -EINVAL;
 361         }
 362         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 363         if (nilfs->ns_sbsize > BLOCK_SIZE)
 364                 return -EINVAL;
 365
 366         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 367         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 368
 369         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 370         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 371                 printk(KERN_ERR "NILFS: too short segment. \n");
 372                 return -EINVAL;
 373         }
 374
 375         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 376         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 377         nilfs->ns_r_segments_percentage =
 378                 le32_to_cpu(sbp->s_r_segments_percentage);
 379         nilfs->ns_nrsvsegs =
 380                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 381                       DIV_ROUND_UP(nilfs->ns_nsegments *
 382                                    nilfs->ns_r_segments_percentage, 100));
 383         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 384         return 0;
 385 }
 386
 387 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 388 {
 389         static unsigned char sum[4];
 390         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 391         size_t bytes;
 392         u32 crc;
 393
 394         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 395                 return 0;
 396         bytes = le16_to_cpu(sbp->s_bytes);
 397         if (bytes > BLOCK_SIZE)
 398                 return 0;
 399         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 400                        sumoff);
 401         crc = crc32_le(crc, sum, 4);
 402         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 403                        bytes - sumoff - 4);
 404         return crc == le32_to_cpu(sbp->s_sum);
 405 }
 406
 407 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 408 {
 409         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 410                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 411                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 412 }
 413
 414 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 415 {
 416         int i;
 417
 418         for (i = 0; i < 2; i++) {
 419                 if (nilfs->ns_sbp[i]) {
 420                         brelse(nilfs->ns_sbh[i]);
 421                         nilfs->ns_sbh[i] = NULL;
 422                         nilfs->ns_sbp[i] = NULL;
 423                 }
 424         }
 425 }
 426
 427 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 428 {
 429         brelse(nilfs->ns_sbh[0]);
 430         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 431         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 432         nilfs->ns_sbh[1] = NULL;
 433         nilfs->ns_sbp[1] = NULL;
 434 }
 435
 436 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 437 {
 438         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 439         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 440
 441         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 442         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 443         nilfs->ns_sbh[1] = tsbh;
 444         nilfs->ns_sbp[1] = tsbp;
 445 }
 446
 447 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 448                                   struct super_block *sb, int blocksize,
 449                                   struct nilfs_super_block **sbpp)
 450 {
 451         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 452         struct buffer_head **sbh = nilfs->ns_sbh;
 453         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 454         int valid[2], swp = 0;
 455
 456         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 457                                         &sbh[0]);
 458         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 459
 460         if (!sbp[0]) {
 461                 if (!sbp[1]) {
 462                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 463                         return -EIO;
 464                 }
 465                 printk(KERN_WARNING
 466                        "NILFS warning: unable to read primary superblock\n");
 467         } else if (!sbp[1])
 468                 printk(KERN_WARNING
 469                        "NILFS warning: unable to read secondary superblock\n");
 470
 471         valid[0] = nilfs_valid_sb(sbp[0]);
 472         valid[1] = nilfs_valid_sb(sbp[1]);
 473         swp = valid[1] &&
 474                 (!valid[0] ||
 475                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
 476
 477         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 478                 brelse(sbh[1]);
 479                 sbh[1] = NULL;
 480                 sbp[1] = NULL;
 481                 swp = 0;
 482         }
 483         if (!valid[swp]) {
 484                 nilfs_release_super_block(nilfs);
 485                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 486                        sb->s_id);
 487                 return -EINVAL;
 488         }
 489
 490         if (swp) {
 491                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 492                        "using spare superblock.\n");
 493                 nilfs_swap_super_block(nilfs);
 494         }
 495
 496         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
 497         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
 498         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 499         *sbpp = sbp[0];
 500         return 0;
 501 }
 502
 503 /**
 504  * init_nilfs - initialize a NILFS instance.
 505  * @nilfs: the_nilfs structure
 506  * @sbi: nilfs_sb_info
 507  * @sb: super block
 508  * @data: mount options
 509  *
 510  * init_nilfs() performs common initialization per block device (e.g.
 511  * reading the super block, getting disk layout information, initializing
 512  * shared fields in the_nilfs). It takes on some portion of the jobs
 513  * typically done by a fill_super() routine. This division arises from
 514  * the nature that multiple NILFS instances may be simultaneously
 515  * mounted on a device.
 516  * For multiple mounts on the same device, only the first mount
 517  * invokes these tasks.
 518  *
 519  * Return Value: On success, 0 is returned. On error, a negative error
 520  * code is returned.
 521  */
 522 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 523 {
 524         struct super_block *sb = sbi->s_super;
 525         struct nilfs_super_block *sbp;
 526         struct backing_dev_info *bdi;
 527         int blocksize;
 528         int err;
 529
 530         down_write(&nilfs->ns_sem);
 531         if (nilfs_init(nilfs)) {
 532                 /* Load values from existing the_nilfs */
 533                 sbp = nilfs->ns_sbp[0];
 534                 err = nilfs_store_magic_and_option(sb, sbp, data);
 535                 if (err)
 536                         goto out;
 537
 538                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 539                 if (sb->s_blocksize != blocksize &&
 540                     !sb_set_blocksize(sb, blocksize)) {
 541                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 542                                blocksize);
 543                         err = -EINVAL;
 544                 }
 545                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 546                 goto out;
 547         }
 548
 549         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 550         if (!blocksize) {
 551                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 552                 err = -EINVAL;
 553                 goto out;
 554         }
 555         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 556         if (err)
 557                 goto out;
 558
 559         err = nilfs_store_magic_and_option(sb, sbp, data);
 560         if (err)
 561                 goto failed_sbh;
 562
 563         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 564         if (sb->s_blocksize != blocksize) {
 565                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 566
 567                 if (blocksize < hw_blocksize) {
 568                         printk(KERN_ERR
 569                                "NILFS: blocksize %d too small for device "
 570                                "(sector-size = %d).\n",
 571                                blocksize, hw_blocksize);
 572                         err = -EINVAL;
 573                         goto failed_sbh;
 574                 }
 575                 nilfs_release_super_block(nilfs);
 576                 sb_set_blocksize(sb, blocksize);
 577
 578                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 579                 if (err)
 580                         goto out;
 581                         /* not failed_sbh; sbh is released automatically
 582                            when reloading fails. */
 583         }
 584         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 585
 586         err = nilfs_store_disk_layout(nilfs, sbp);
 587         if (err)
 588                 goto failed_sbh;
 589
 590         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 591
 592         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 593
 594         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 595         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 596
 597         /* Finding last segment */
 598         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 599         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 600         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 601
 602         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 603         nilfs->ns_segnum =
 604                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 605         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 606         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 607                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 608                 err = -EINVAL;
 609                 goto failed_sbh;
 610         }
 611         /* Dummy values  */
 612         nilfs->ns_free_segments_count =
 613                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
 614
 615         /* Initialize gcinode cache */
 616         err = nilfs_init_gccache(nilfs);
 617         if (err)
 618                 goto failed_sbh;
 619
 620         set_nilfs_init(nilfs);
 621         err = 0;
 622  out:
 623         up_write(&nilfs->ns_sem);
 624         return err;
 625
 626  failed_sbh:
 627         nilfs_release_super_block(nilfs);
 628         goto out;
 629 }
 630
 631 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 632 {
 633         struct inode *dat = nilfs_dat_inode(nilfs);
 634         unsigned long ncleansegs;
 635         int err;
 636
 637         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 638         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
 639         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 640         if (likely(!err))
 641                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 642         return err;
 643 }
 644
 645 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 646 {
 647         struct inode *sufile = nilfs->ns_sufile;
 648         unsigned long ncleansegs, nincsegs;
 649         int ret;
 650
 651         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
 652         if (likely(!ret)) {
 653                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 654                         nilfs->ns_blocks_per_segment + 1;
 655                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
 656                         ret++;
 657         }
 658         return ret;
 659 }
 660
 661 /**
 662  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
 663  * @nilfs: nilfs object
 664  * @rw_mount: mount type (non-zero value for read/write mount)
 665  * @cno: checkpoint number (zero for read-only mount)
 666  *
 667  * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
 668  * @rw_mount and @cno (in case of snapshots) matched.  If no instance
 669  * was found, NULL is returned.  Although the super block instance can
 670  * be unmounted after this function returns, the nilfs_sb_info struct
 671  * is kept on memory until nilfs_put_sbinfo() is called.
 672  */
 673 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
 674                                         int rw_mount, __u64 cno)
 675 {
 676         struct nilfs_sb_info *sbi;
 677
 678         down_read(&nilfs->ns_super_sem);
 679         /*
 680          * The SNAPSHOT flag and sb->s_flags are supposed to be
 681          * protected with nilfs->ns_super_sem.
 682          */
 683         sbi = nilfs->ns_current;
 684         if (rw_mount) {
 685                 if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
 686                         goto found; /* read/write mount */
 687                 else
 688                         goto out;
 689         } else if (cno == 0) {
 690                 if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
 691                         goto found; /* read-only mount */
 692                 else
 693                         goto out;
 694         }
 695
 696         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 697                 if (nilfs_test_opt(sbi, SNAPSHOT) &&
 698                     sbi->s_snapshot_cno == cno)
 699                         goto found; /* snapshot mount */
 700         }
 701  out:
 702         up_read(&nilfs->ns_super_sem);
 703         return NULL;
 704
 705  found:
 706         atomic_inc(&sbi->s_count);
 707         up_read(&nilfs->ns_super_sem);
 708         return sbi;
 709 }
 710
 711 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 712                                 int snapshot_mount)
 713 {
 714         struct nilfs_sb_info *sbi;
 715         int ret = 0;
 716
 717         down_read(&nilfs->ns_super_sem);
 718         if (cno == 0 || cno > nilfs->ns_cno)
 719                 goto out_unlock;
 720
 721         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 722                 if (sbi->s_snapshot_cno == cno &&
 723                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 724                                         /* exclude read-only mounts */
 725                         ret++;
 726                         break;
 727                 }
 728         }
 729         /* for protecting recent checkpoints */
 730         if (cno >= nilfs_last_cno(nilfs))
 731                 ret++;
 732
 733  out_unlock:
 734         up_read(&nilfs->ns_super_sem);
 735         return ret;
 736 }