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