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 static int nilfs_valid_sb(struct nilfs_super_block *sbp);
  42
  43 void nilfs_set_last_segment(struct the_nilfs *nilfs,
  44                             sector_t start_blocknr, u64 seq, __u64 cno)
  45 {
  46         spin_lock(&nilfs->ns_last_segment_lock);
  47         nilfs->ns_last_pseg = start_blocknr;
  48         nilfs->ns_last_seq = seq;
  49         nilfs->ns_last_cno = cno;
  50
  51         if (!nilfs_sb_dirty(nilfs)) {
  52                 if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
  53                         goto stay_cursor;
  54
  55                 set_nilfs_sb_dirty(nilfs);
  56         }
  57         nilfs->ns_prev_seq = nilfs->ns_last_seq;
  58
  59  stay_cursor:
  60         spin_unlock(&nilfs->ns_last_segment_lock);
  61 }
  62
  63 /**
  64  * alloc_nilfs - allocate the_nilfs structure
  65  * @bdev: block device to which the_nilfs is related
  66  *
  67  * alloc_nilfs() allocates memory for the_nilfs and
  68  * initializes its reference count and locks.
  69  *
  70  * Return Value: On success, pointer to the_nilfs is returned.
  71  * On error, NULL is returned.
  72  */
  73 static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  74 {
  75         struct the_nilfs *nilfs;
  76
  77         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  78         if (!nilfs)
  79                 return NULL;
  80
  81         nilfs->ns_bdev = bdev;
  82         atomic_set(&nilfs->ns_count, 1);
  83         atomic_set(&nilfs->ns_ndirtyblks, 0);
  84         init_rwsem(&nilfs->ns_sem);
  85         init_rwsem(&nilfs->ns_super_sem);
  86         mutex_init(&nilfs->ns_mount_mutex);
  87         init_rwsem(&nilfs->ns_writer_sem);
  88         INIT_LIST_HEAD(&nilfs->ns_list);
  89         INIT_LIST_HEAD(&nilfs->ns_supers);
  90         spin_lock_init(&nilfs->ns_last_segment_lock);
  91         nilfs->ns_gc_inodes_h = NULL;
  92         init_rwsem(&nilfs->ns_segctor_sem);
  93
  94         return nilfs;
  95 }
  96
  97 /**
  98  * find_or_create_nilfs - find or create nilfs object
  99  * @bdev: block device to which the_nilfs is related
 100  *
 101  * find_nilfs() looks up an existent nilfs object created on the
 102  * device and gets the reference count of the object.  If no nilfs object
 103  * is found on the device, a new nilfs object is allocated.
 104  *
 105  * Return Value: On success, pointer to the nilfs object is returned.
 106  * On error, NULL is returned.
 107  */
 108 struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)
 109 {
 110         struct the_nilfs *nilfs, *new = NULL;
 111
 112  retry:
 113         spin_lock(&nilfs_lock);
 114         list_for_each_entry(nilfs, &nilfs_objects, ns_list) {
 115                 if (nilfs->ns_bdev == bdev) {
 116                         get_nilfs(nilfs);
 117                         spin_unlock(&nilfs_lock);
 118                         if (new)
 119                                 put_nilfs(new);
 120                         return nilfs; /* existing object */
 121                 }
 122         }
 123         if (new) {
 124                 list_add_tail(&new->ns_list, &nilfs_objects);
 125                 spin_unlock(&nilfs_lock);
 126                 return new; /* new object */
 127         }
 128         spin_unlock(&nilfs_lock);
 129
 130         new = alloc_nilfs(bdev);
 131         if (new)
 132                 goto retry;
 133         return NULL; /* insufficient memory */
 134 }
 135
 136 /**
 137  * put_nilfs - release a reference to the_nilfs
 138  * @nilfs: the_nilfs structure to be released
 139  *
 140  * put_nilfs() decrements a reference counter of the_nilfs.
 141  * If the reference count reaches zero, the_nilfs is freed.
 142  */
 143 void put_nilfs(struct the_nilfs *nilfs)
 144 {
 145         spin_lock(&nilfs_lock);
 146         if (!atomic_dec_and_test(&nilfs->ns_count)) {
 147                 spin_unlock(&nilfs_lock);
 148                 return;
 149         }
 150         list_del_init(&nilfs->ns_list);
 151         spin_unlock(&nilfs_lock);
 152
 153         /*
 154          * Increment of ns_count never occurs below because the caller
 155          * of get_nilfs() holds at least one reference to the_nilfs.
 156          * Thus its exclusion control is not required here.
 157          */
 158
 159         might_sleep();
 160         if (nilfs_loaded(nilfs)) {
 161                 nilfs_mdt_destroy(nilfs->ns_sufile);
 162                 nilfs_mdt_destroy(nilfs->ns_cpfile);
 163                 nilfs_mdt_destroy(nilfs->ns_dat);
 164                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
 165         }
 166         if (nilfs_init(nilfs)) {
 167                 nilfs_destroy_gccache(nilfs);
 168                 brelse(nilfs->ns_sbh[0]);
 169                 brelse(nilfs->ns_sbh[1]);
 170         }
 171         kfree(nilfs);
 172 }
 173
 174 static int nilfs_load_super_root(struct the_nilfs *nilfs, sector_t sr_block)
 175 {
 176         struct buffer_head *bh_sr;
 177         struct nilfs_super_root *raw_sr;
 178         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 179         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 180         unsigned inode_size;
 181         int err;
 182
 183         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
 184         if (unlikely(err))
 185                 return err;
 186
 187         down_read(&nilfs->ns_sem);
 188         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 189         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 190         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 191         up_read(&nilfs->ns_sem);
 192
 193         inode_size = nilfs->ns_inode_size;
 194
 195         err = -ENOMEM;
 196         nilfs->ns_dat = nilfs_dat_new(nilfs, dat_entry_size);
 197         if (unlikely(!nilfs->ns_dat))
 198                 goto failed;
 199
 200         nilfs->ns_gc_dat = nilfs_dat_new(nilfs, dat_entry_size);
 201         if (unlikely(!nilfs->ns_gc_dat))
 202                 goto failed_dat;
 203
 204         nilfs->ns_cpfile = nilfs_cpfile_new(nilfs, checkpoint_size);
 205         if (unlikely(!nilfs->ns_cpfile))
 206                 goto failed_gc_dat;
 207
 208         nilfs->ns_sufile = nilfs_sufile_new(nilfs, segment_usage_size);
 209         if (unlikely(!nilfs->ns_sufile))
 210                 goto failed_cpfile;
 211
 212         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
 213
 214         err = nilfs_dat_read(nilfs->ns_dat, (void *)bh_sr->b_data +
 215                              NILFS_SR_DAT_OFFSET(inode_size));
 216         if (unlikely(err))
 217                 goto failed_sufile;
 218
 219         err = nilfs_cpfile_read(nilfs->ns_cpfile, (void *)bh_sr->b_data +
 220                                 NILFS_SR_CPFILE_OFFSET(inode_size));
 221         if (unlikely(err))
 222                 goto failed_sufile;
 223
 224         err = nilfs_sufile_read(nilfs->ns_sufile, (void *)bh_sr->b_data +
 225                                 NILFS_SR_SUFILE_OFFSET(inode_size));
 226         if (unlikely(err))
 227                 goto failed_sufile;
 228
 229         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 230         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 231
 232  failed:
 233         brelse(bh_sr);
 234         return err;
 235
 236  failed_sufile:
 237         nilfs_mdt_destroy(nilfs->ns_sufile);
 238
 239  failed_cpfile:
 240         nilfs_mdt_destroy(nilfs->ns_cpfile);
 241
 242  failed_gc_dat:
 243         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 244
 245  failed_dat:
 246         nilfs_mdt_destroy(nilfs->ns_dat);
 247         goto failed;
 248 }
 249
 250 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 251 {
 252         memset(ri, 0, sizeof(*ri));
 253         INIT_LIST_HEAD(&ri->ri_used_segments);
 254 }
 255
 256 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 257 {
 258         nilfs_dispose_segment_list(&ri->ri_used_segments);
 259 }
 260
 261 /**
 262  * nilfs_store_log_cursor - load log cursor from a super block
 263  * @nilfs: nilfs object
 264  * @sbp: buffer storing super block to be read
 265  *
 266  * nilfs_store_log_cursor() reads the last position of the log
 267  * containing a super root from a given super block, and initializes
 268  * relevant information on the nilfs object preparatory for log
 269  * scanning and recovery.
 270  */
 271 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
 272                                   struct nilfs_super_block *sbp)
 273 {
 274         int ret = 0;
 275
 276         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 277         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 278         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 279
 280         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 281         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 282         nilfs->ns_segnum =
 283                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 284         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 285         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 286                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 287                 ret = -EINVAL;
 288         }
 289         return ret;
 290 }
 291
 292 /**
 293  * load_nilfs - load and recover the nilfs
 294  * @nilfs: the_nilfs structure to be released
 295  * @sbi: nilfs_sb_info used to recover past segment
 296  *
 297  * load_nilfs() searches and load the latest super root,
 298  * attaches the last segment, and does recovery if needed.
 299  * The caller must call this exclusively for simultaneous mounts.
 300  */
 301 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 302 {
 303         struct nilfs_recovery_info ri;
 304         unsigned int s_flags = sbi->s_super->s_flags;
 305         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 306         int valid_fs = nilfs_valid_fs(nilfs);
 307         int err;
 308
 309         if (nilfs_loaded(nilfs)) {
 310                 if (valid_fs ||
 311                     ((s_flags & MS_RDONLY) && nilfs_test_opt(sbi, NORECOVERY)))
 312                         return 0;
 313                 printk(KERN_ERR "NILFS: the filesystem is in an incomplete "
 314                        "recovery state.\n");
 315                 return -EINVAL;
 316         }
 317
 318         if (!valid_fs) {
 319                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
 320                 if (s_flags & MS_RDONLY) {
 321                         printk(KERN_INFO "NILFS: INFO: recovery "
 322                                "required for readonly filesystem.\n");
 323                         printk(KERN_INFO "NILFS: write access will "
 324                                "be enabled during recovery.\n");
 325                 }
 326         }
 327
 328         nilfs_init_recovery_info(&ri);
 329
 330         err = nilfs_search_super_root(nilfs, &ri);
 331         if (unlikely(err)) {
 332                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 333                 int blocksize;
 334
 335                 if (err != -EINVAL)
 336                         goto scan_error;
 337
 338                 if (!nilfs_valid_sb(sbp[1])) {
 339                         printk(KERN_WARNING
 340                                "NILFS warning: unable to fall back to spare"
 341                                "super block\n");
 342                         goto scan_error;
 343                 }
 344                 printk(KERN_INFO
 345                        "NILFS: try rollback from an earlier position\n");
 346
 347                 /*
 348                  * restore super block with its spare and reconfigure
 349                  * relevant states of the nilfs object.
 350                  */
 351                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 352                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 353                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 354
 355                 /* verify consistency between two super blocks */
 356                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
 357                 if (blocksize != nilfs->ns_blocksize) {
 358                         printk(KERN_WARNING
 359                                "NILFS warning: blocksize differs between "
 360                                "two super blocks (%d != %d)\n",
 361                                blocksize, nilfs->ns_blocksize);
 362                         goto scan_error;
 363                 }
 364
 365                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 366                 if (err)
 367                         goto scan_error;
 368
 369                 /* drop clean flag to allow roll-forward and recovery */
 370                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 371                 valid_fs = 0;
 372
 373                 err = nilfs_search_super_root(nilfs, &ri);
 374                 if (err)
 375                         goto scan_error;
 376         }
 377
 378         err = nilfs_load_super_root(nilfs, ri.ri_super_root);
 379         if (unlikely(err)) {
 380                 printk(KERN_ERR "NILFS: error loading super root.\n");
 381                 goto failed;
 382         }
 383
 384         if (valid_fs)
 385                 goto skip_recovery;
 386
 387         if (s_flags & MS_RDONLY) {
 388                 if (nilfs_test_opt(sbi, NORECOVERY)) {
 389                         printk(KERN_INFO "NILFS: norecovery option specified. "
 390                                "skipping roll-forward recovery\n");
 391                         goto skip_recovery;
 392                 }
 393                 if (really_read_only) {
 394                         printk(KERN_ERR "NILFS: write access "
 395                                "unavailable, cannot proceed.\n");
 396                         err = -EROFS;
 397                         goto failed_unload;
 398                 }
 399                 sbi->s_super->s_flags &= ~MS_RDONLY;
 400         } else if (nilfs_test_opt(sbi, NORECOVERY)) {
 401                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
 402                        "option was specified for a read/write mount\n");
 403                 err = -EINVAL;
 404                 goto failed_unload;
 405         }
 406
 407         err = nilfs_salvage_orphan_logs(nilfs, sbi, &ri);
 408         if (err)
 409                 goto failed_unload;
 410
 411         down_write(&nilfs->ns_sem);
 412         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 413         err = nilfs_cleanup_super(sbi);
 414         up_write(&nilfs->ns_sem);
 415
 416         if (err) {
 417                 printk(KERN_ERR "NILFS: failed to update super block. "
 418                        "recovery unfinished.\n");
 419                 goto failed_unload;
 420         }
 421         printk(KERN_INFO "NILFS: recovery complete.\n");
 422
 423  skip_recovery:
 424         set_nilfs_loaded(nilfs);
 425         nilfs_clear_recovery_info(&ri);
 426         sbi->s_super->s_flags = s_flags;
 427         return 0;
 428
 429  scan_error:
 430         printk(KERN_ERR "NILFS: error searching super root.\n");
 431         goto failed;
 432
 433  failed_unload:
 434         nilfs_mdt_destroy(nilfs->ns_cpfile);
 435         nilfs_mdt_destroy(nilfs->ns_sufile);
 436         nilfs_mdt_destroy(nilfs->ns_dat);
 437
 438  failed:
 439         nilfs_clear_recovery_info(&ri);
 440         sbi->s_super->s_flags = s_flags;
 441         return err;
 442 }
 443
 444 static unsigned long long nilfs_max_size(unsigned int blkbits)
 445 {
 446         unsigned int max_bits;
 447         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 448
 449         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 450         if (max_bits < 64)
 451                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 452         return res;
 453 }
 454
 455 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 456                                    struct nilfs_super_block *sbp)
 457 {
 458         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 459                 printk(KERN_ERR "NILFS: revision mismatch "
 460                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 461                        "Please check the version of mkfs.nilfs.\n",
 462                        le32_to_cpu(sbp->s_rev_level),
 463                        le16_to_cpu(sbp->s_minor_rev_level),
 464                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 465                 return -EINVAL;
 466         }
 467         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 468         if (nilfs->ns_sbsize > BLOCK_SIZE)
 469                 return -EINVAL;
 470
 471         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 472         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 473
 474         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 475         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 476                 printk(KERN_ERR "NILFS: too short segment.\n");
 477                 return -EINVAL;
 478         }
 479
 480         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 481         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 482         nilfs->ns_r_segments_percentage =
 483                 le32_to_cpu(sbp->s_r_segments_percentage);
 484         nilfs->ns_nrsvsegs =
 485                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 486                       DIV_ROUND_UP(nilfs->ns_nsegments *
 487                                    nilfs->ns_r_segments_percentage, 100));
 488         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 489         return 0;
 490 }
 491
 492 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 493 {
 494         static unsigned char sum[4];
 495         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 496         size_t bytes;
 497         u32 crc;
 498
 499         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 500                 return 0;
 501         bytes = le16_to_cpu(sbp->s_bytes);
 502         if (bytes > BLOCK_SIZE)
 503                 return 0;
 504         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 505                        sumoff);
 506         crc = crc32_le(crc, sum, 4);
 507         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 508                        bytes - sumoff - 4);
 509         return crc == le32_to_cpu(sbp->s_sum);
 510 }
 511
 512 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 513 {
 514         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 515                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 516                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 517 }
 518
 519 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 520 {
 521         int i;
 522
 523         for (i = 0; i < 2; i++) {
 524                 if (nilfs->ns_sbp[i]) {
 525                         brelse(nilfs->ns_sbh[i]);
 526                         nilfs->ns_sbh[i] = NULL;
 527                         nilfs->ns_sbp[i] = NULL;
 528                 }
 529         }
 530 }
 531
 532 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 533 {
 534         brelse(nilfs->ns_sbh[0]);
 535         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 536         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 537         nilfs->ns_sbh[1] = NULL;
 538         nilfs->ns_sbp[1] = NULL;
 539 }
 540
 541 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 542 {
 543         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 544         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 545
 546         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 547         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 548         nilfs->ns_sbh[1] = tsbh;
 549         nilfs->ns_sbp[1] = tsbp;
 550 }
 551
 552 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 553                                   struct super_block *sb, int blocksize,
 554                                   struct nilfs_super_block **sbpp)
 555 {
 556         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 557         struct buffer_head **sbh = nilfs->ns_sbh;
 558         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 559         int valid[2], swp = 0;
 560
 561         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 562                                         &sbh[0]);
 563         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 564
 565         if (!sbp[0]) {
 566                 if (!sbp[1]) {
 567                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 568                         return -EIO;
 569                 }
 570                 printk(KERN_WARNING
 571                        "NILFS warning: unable to read primary superblock\n");
 572         } else if (!sbp[1])
 573                 printk(KERN_WARNING
 574                        "NILFS warning: unable to read secondary superblock\n");
 575
 576         /*
 577          * Compare two super blocks and set 1 in swp if the secondary
 578          * super block is valid and newer.  Otherwise, set 0 in swp.
 579          */
 580         valid[0] = nilfs_valid_sb(sbp[0]);
 581         valid[1] = nilfs_valid_sb(sbp[1]);
 582         swp = valid[1] && (!valid[0] ||
 583                            le64_to_cpu(sbp[1]->s_last_cno) >
 584                            le64_to_cpu(sbp[0]->s_last_cno));
 585
 586         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 587                 brelse(sbh[1]);
 588                 sbh[1] = NULL;
 589                 sbp[1] = NULL;
 590                 swp = 0;
 591         }
 592         if (!valid[swp]) {
 593                 nilfs_release_super_block(nilfs);
 594                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 595                        sb->s_id);
 596                 return -EINVAL;
 597         }
 598
 599         if (swp) {
 600                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 601                        "using spare superblock.\n");
 602                 nilfs_swap_super_block(nilfs);
 603         }
 604
 605         nilfs->ns_sbwcount = 0;
 606         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 607         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 608         *sbpp = sbp[0];
 609         return 0;
 610 }
 611
 612 /**
 613  * init_nilfs - initialize a NILFS instance.
 614  * @nilfs: the_nilfs structure
 615  * @sbi: nilfs_sb_info
 616  * @sb: super block
 617  * @data: mount options
 618  *
 619  * init_nilfs() performs common initialization per block device (e.g.
 620  * reading the super block, getting disk layout information, initializing
 621  * shared fields in the_nilfs). It takes on some portion of the jobs
 622  * typically done by a fill_super() routine. This division arises from
 623  * the nature that multiple NILFS instances may be simultaneously
 624  * mounted on a device.
 625  * For multiple mounts on the same device, only the first mount
 626  * invokes these tasks.
 627  *
 628  * Return Value: On success, 0 is returned. On error, a negative error
 629  * code is returned.
 630  */
 631 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 632 {
 633         struct super_block *sb = sbi->s_super;
 634         struct nilfs_super_block *sbp;
 635         struct backing_dev_info *bdi;
 636         int blocksize;
 637         int err;
 638
 639         down_write(&nilfs->ns_sem);
 640         if (nilfs_init(nilfs)) {
 641                 /* Load values from existing the_nilfs */
 642                 sbp = nilfs->ns_sbp[0];
 643                 err = nilfs_store_magic_and_option(sb, sbp, data);
 644                 if (err)
 645                         goto out;
 646
 647                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 648                 if (sb->s_blocksize != blocksize &&
 649                     !sb_set_blocksize(sb, blocksize)) {
 650                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 651                                blocksize);
 652                         err = -EINVAL;
 653                 }
 654                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 655                 goto out;
 656         }
 657
 658         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 659         if (!blocksize) {
 660                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 661                 err = -EINVAL;
 662                 goto out;
 663         }
 664         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 665         if (err)
 666                 goto out;
 667
 668         err = nilfs_store_magic_and_option(sb, sbp, data);
 669         if (err)
 670                 goto failed_sbh;
 671
 672         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 673         if (sb->s_blocksize != blocksize) {
 674                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 675
 676                 if (blocksize < hw_blocksize) {
 677                         printk(KERN_ERR
 678                                "NILFS: blocksize %d too small for device "
 679                                "(sector-size = %d).\n",
 680                                blocksize, hw_blocksize);
 681                         err = -EINVAL;
 682                         goto failed_sbh;
 683                 }
 684                 nilfs_release_super_block(nilfs);
 685                 sb_set_blocksize(sb, blocksize);
 686
 687                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 688                 if (err)
 689                         goto out;
 690                         /* not failed_sbh; sbh is released automatically
 691                            when reloading fails. */
 692         }
 693         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 694         nilfs->ns_blocksize = blocksize;
 695
 696         err = nilfs_store_disk_layout(nilfs, sbp);
 697         if (err)
 698                 goto failed_sbh;
 699
 700         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 701
 702         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 703
 704         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 705         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 706
 707         err = nilfs_store_log_cursor(nilfs, sbp);
 708         if (err)
 709                 goto failed_sbh;
 710
 711         /* Initialize gcinode cache */
 712         err = nilfs_init_gccache(nilfs);
 713         if (err)
 714                 goto failed_sbh;
 715
 716         set_nilfs_init(nilfs);
 717         err = 0;
 718  out:
 719         up_write(&nilfs->ns_sem);
 720         return err;
 721
 722  failed_sbh:
 723         nilfs_release_super_block(nilfs);
 724         goto out;
 725 }
 726
 727 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 728                             size_t nsegs)
 729 {
 730         sector_t seg_start, seg_end;
 731         sector_t start = 0, nblocks = 0;
 732         unsigned int sects_per_block;
 733         __u64 *sn;
 734         int ret = 0;
 735
 736         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 737                 bdev_logical_block_size(nilfs->ns_bdev);
 738         for (sn = segnump; sn < segnump + nsegs; sn++) {
 739                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 740
 741                 if (!nblocks) {
 742                         start = seg_start;
 743                         nblocks = seg_end - seg_start + 1;
 744                 } else if (start + nblocks == seg_start) {
 745                         nblocks += seg_end - seg_start + 1;
 746                 } else {
 747                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 748                                                    start * sects_per_block,
 749                                                    nblocks * sects_per_block,
 750                                                    GFP_NOFS,
 751                                                    BLKDEV_IFL_BARRIER);
 752                         if (ret < 0)
 753                                 return ret;
 754                         nblocks = 0;
 755                 }
 756         }
 757         if (nblocks)
 758                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 759                                            start * sects_per_block,
 760                                            nblocks * sects_per_block,
 761                                            GFP_NOFS, BLKDEV_IFL_BARRIER);
 762         return ret;
 763 }
 764
 765 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 766 {
 767         struct inode *dat = nilfs_dat_inode(nilfs);
 768         unsigned long ncleansegs;
 769
 770         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 771         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 772         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 773         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 774         return 0;
 775 }
 776
 777 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 778 {
 779         unsigned long ncleansegs, nincsegs;
 780
 781         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 782         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 783                 nilfs->ns_blocks_per_segment + 1;
 784
 785         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 786 }
 787
 788 /**
 789  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
 790  * @nilfs: nilfs object
 791  * @rw_mount: mount type (non-zero value for read/write mount)
 792  * @cno: checkpoint number (zero for read-only mount)
 793  *
 794  * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
 795  * @rw_mount and @cno (in case of snapshots) matched.  If no instance
 796  * was found, NULL is returned.  Although the super block instance can
 797  * be unmounted after this function returns, the nilfs_sb_info struct
 798  * is kept on memory until nilfs_put_sbinfo() is called.
 799  */
 800 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
 801                                         int rw_mount, __u64 cno)
 802 {
 803         struct nilfs_sb_info *sbi;
 804
 805         down_read(&nilfs->ns_super_sem);
 806         /*
 807          * The SNAPSHOT flag and sb->s_flags are supposed to be
 808          * protected with nilfs->ns_super_sem.
 809          */
 810         sbi = nilfs->ns_current;
 811         if (rw_mount) {
 812                 if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
 813                         goto found; /* read/write mount */
 814                 else
 815                         goto out;
 816         } else if (cno == 0) {
 817                 if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
 818                         goto found; /* read-only mount */
 819                 else
 820                         goto out;
 821         }
 822
 823         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 824                 if (nilfs_test_opt(sbi, SNAPSHOT) &&
 825                     sbi->s_snapshot_cno == cno)
 826                         goto found; /* snapshot mount */
 827         }
 828  out:
 829         up_read(&nilfs->ns_super_sem);
 830         return NULL;
 831
 832  found:
 833         atomic_inc(&sbi->s_count);
 834         up_read(&nilfs->ns_super_sem);
 835         return sbi;
 836 }
 837
 838 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 839                                 int snapshot_mount)
 840 {
 841         struct nilfs_sb_info *sbi;
 842         int ret = 0;
 843
 844         down_read(&nilfs->ns_super_sem);
 845         if (cno == 0 || cno > nilfs->ns_cno)
 846                 goto out_unlock;
 847
 848         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 849                 if (sbi->s_snapshot_cno == cno &&
 850                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 851                                         /* exclude read-only mounts */
 852                         ret++;
 853                         break;
 854                 }
 855         }
 856         /* for protecting recent checkpoints */
 857         if (cno >= nilfs_last_cno(nilfs))
 858                 ret++;
 859
 860  out_unlock:
 861         up_read(&nilfs->ns_super_sem);
 862         return ret;
 863 }