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