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