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                 __u64 features;
 389
 390                 if (nilfs_test_opt(sbi, NORECOVERY)) {
 391                         printk(KERN_INFO "NILFS: norecovery option specified. "
 392                                "skipping roll-forward recovery\n");
 393                         goto skip_recovery;
 394                 }
 395                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 396                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 397                 if (features) {
 398                         printk(KERN_ERR "NILFS: couldn't proceed with "
 399                                "recovery because of unsupported optional "
 400                                "features (%llx)\n",
 401                                (unsigned long long)features);
 402                         err = -EROFS;
 403                         goto failed_unload;
 404                 }
 405                 if (really_read_only) {
 406                         printk(KERN_ERR "NILFS: write access "
 407                                "unavailable, cannot proceed.\n");
 408                         err = -EROFS;
 409                         goto failed_unload;
 410                 }
 411                 sbi->s_super->s_flags &= ~MS_RDONLY;
 412         } else if (nilfs_test_opt(sbi, NORECOVERY)) {
 413                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
 414                        "option was specified for a read/write mount\n");
 415                 err = -EINVAL;
 416                 goto failed_unload;
 417         }
 418
 419         err = nilfs_salvage_orphan_logs(nilfs, sbi, &ri);
 420         if (err)
 421                 goto failed_unload;
 422
 423         down_write(&nilfs->ns_sem);
 424         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 425         err = nilfs_cleanup_super(sbi);
 426         up_write(&nilfs->ns_sem);
 427
 428         if (err) {
 429                 printk(KERN_ERR "NILFS: failed to update super block. "
 430                        "recovery unfinished.\n");
 431                 goto failed_unload;
 432         }
 433         printk(KERN_INFO "NILFS: recovery complete.\n");
 434
 435  skip_recovery:
 436         set_nilfs_loaded(nilfs);
 437         nilfs_clear_recovery_info(&ri);
 438         sbi->s_super->s_flags = s_flags;
 439         return 0;
 440
 441  scan_error:
 442         printk(KERN_ERR "NILFS: error searching super root.\n");
 443         goto failed;
 444
 445  failed_unload:
 446         nilfs_mdt_destroy(nilfs->ns_cpfile);
 447         nilfs_mdt_destroy(nilfs->ns_sufile);
 448         nilfs_mdt_destroy(nilfs->ns_dat);
 449         nilfs_mdt_destroy(nilfs->ns_gc_dat);
 450
 451  failed:
 452         nilfs_clear_recovery_info(&ri);
 453         sbi->s_super->s_flags = s_flags;
 454         return err;
 455 }
 456
 457 static unsigned long long nilfs_max_size(unsigned int blkbits)
 458 {
 459         unsigned int max_bits;
 460         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 461
 462         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 463         if (max_bits < 64)
 464                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 465         return res;
 466 }
 467
 468 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 469                                    struct nilfs_super_block *sbp)
 470 {
 471         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
 472                 printk(KERN_ERR "NILFS: revision mismatch "
 473                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 474                        "Please check the version of mkfs.nilfs.\n",
 475                        le32_to_cpu(sbp->s_rev_level),
 476                        le16_to_cpu(sbp->s_minor_rev_level),
 477                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 478                 return -EINVAL;
 479         }
 480         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 481         if (nilfs->ns_sbsize > BLOCK_SIZE)
 482                 return -EINVAL;
 483
 484         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 485         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 486
 487         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 488         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 489                 printk(KERN_ERR "NILFS: too short segment.\n");
 490                 return -EINVAL;
 491         }
 492
 493         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 494         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
 495         nilfs->ns_r_segments_percentage =
 496                 le32_to_cpu(sbp->s_r_segments_percentage);
 497         nilfs->ns_nrsvsegs =
 498                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 499                       DIV_ROUND_UP(nilfs->ns_nsegments *
 500                                    nilfs->ns_r_segments_percentage, 100));
 501         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 502         return 0;
 503 }
 504
 505 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 506 {
 507         static unsigned char sum[4];
 508         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 509         size_t bytes;
 510         u32 crc;
 511
 512         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 513                 return 0;
 514         bytes = le16_to_cpu(sbp->s_bytes);
 515         if (bytes > BLOCK_SIZE)
 516                 return 0;
 517         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 518                        sumoff);
 519         crc = crc32_le(crc, sum, 4);
 520         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 521                        bytes - sumoff - 4);
 522         return crc == le32_to_cpu(sbp->s_sum);
 523 }
 524
 525 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 526 {
 527         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 528                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 529                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 530 }
 531
 532 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 533 {
 534         int i;
 535
 536         for (i = 0; i < 2; i++) {
 537                 if (nilfs->ns_sbp[i]) {
 538                         brelse(nilfs->ns_sbh[i]);
 539                         nilfs->ns_sbh[i] = NULL;
 540                         nilfs->ns_sbp[i] = NULL;
 541                 }
 542         }
 543 }
 544
 545 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 546 {
 547         brelse(nilfs->ns_sbh[0]);
 548         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 549         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 550         nilfs->ns_sbh[1] = NULL;
 551         nilfs->ns_sbp[1] = NULL;
 552 }
 553
 554 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 555 {
 556         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 557         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 558
 559         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 560         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 561         nilfs->ns_sbh[1] = tsbh;
 562         nilfs->ns_sbp[1] = tsbp;
 563 }
 564
 565 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 566                                   struct super_block *sb, int blocksize,
 567                                   struct nilfs_super_block **sbpp)
 568 {
 569         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 570         struct buffer_head **sbh = nilfs->ns_sbh;
 571         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 572         int valid[2], swp = 0;
 573
 574         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 575                                         &sbh[0]);
 576         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 577
 578         if (!sbp[0]) {
 579                 if (!sbp[1]) {
 580                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 581                         return -EIO;
 582                 }
 583                 printk(KERN_WARNING
 584                        "NILFS warning: unable to read primary superblock\n");
 585         } else if (!sbp[1])
 586                 printk(KERN_WARNING
 587                        "NILFS warning: unable to read secondary superblock\n");
 588
 589         /*
 590          * Compare two super blocks and set 1 in swp if the secondary
 591          * super block is valid and newer.  Otherwise, set 0 in swp.
 592          */
 593         valid[0] = nilfs_valid_sb(sbp[0]);
 594         valid[1] = nilfs_valid_sb(sbp[1]);
 595         swp = valid[1] && (!valid[0] ||
 596                            le64_to_cpu(sbp[1]->s_last_cno) >
 597                            le64_to_cpu(sbp[0]->s_last_cno));
 598
 599         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 600                 brelse(sbh[1]);
 601                 sbh[1] = NULL;
 602                 sbp[1] = NULL;
 603                 swp = 0;
 604         }
 605         if (!valid[swp]) {
 606                 nilfs_release_super_block(nilfs);
 607                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 608                        sb->s_id);
 609                 return -EINVAL;
 610         }
 611
 612         if (!valid[!swp])
 613                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 614                        "using spare superblock.\n");
 615         if (swp)
 616                 nilfs_swap_super_block(nilfs);
 617
 618         nilfs->ns_sbwcount = 0;
 619         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 620         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 621         *sbpp = sbp[0];
 622         return 0;
 623 }
 624
 625 /**
 626  * init_nilfs - initialize a NILFS instance.
 627  * @nilfs: the_nilfs structure
 628  * @sbi: nilfs_sb_info
 629  * @sb: super block
 630  * @data: mount options
 631  *
 632  * init_nilfs() performs common initialization per block device (e.g.
 633  * reading the super block, getting disk layout information, initializing
 634  * shared fields in the_nilfs). It takes on some portion of the jobs
 635  * typically done by a fill_super() routine. This division arises from
 636  * the nature that multiple NILFS instances may be simultaneously
 637  * mounted on a device.
 638  * For multiple mounts on the same device, only the first mount
 639  * invokes these tasks.
 640  *
 641  * Return Value: On success, 0 is returned. On error, a negative error
 642  * code is returned.
 643  */
 644 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
 645 {
 646         struct super_block *sb = sbi->s_super;
 647         struct nilfs_super_block *sbp;
 648         struct backing_dev_info *bdi;
 649         int blocksize;
 650         int err;
 651
 652         down_write(&nilfs->ns_sem);
 653         if (nilfs_init(nilfs)) {
 654                 /* Load values from existing the_nilfs */
 655                 sbp = nilfs->ns_sbp[0];
 656                 err = nilfs_store_magic_and_option(sb, sbp, data);
 657                 if (err)
 658                         goto out;
 659
 660                 err = nilfs_check_feature_compatibility(sb, sbp);
 661                 if (err)
 662                         goto out;
 663
 664                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 665                 if (sb->s_blocksize != blocksize &&
 666                     !sb_set_blocksize(sb, blocksize)) {
 667                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
 668                                blocksize);
 669                         err = -EINVAL;
 670                 }
 671                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 672                 goto out;
 673         }
 674
 675         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 676         if (!blocksize) {
 677                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 678                 err = -EINVAL;
 679                 goto out;
 680         }
 681         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 682         if (err)
 683                 goto out;
 684
 685         err = nilfs_store_magic_and_option(sb, sbp, data);
 686         if (err)
 687                 goto failed_sbh;
 688
 689         err = nilfs_check_feature_compatibility(sb, sbp);
 690         if (err)
 691                 goto failed_sbh;
 692
 693         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 694         if (blocksize < NILFS_MIN_BLOCK_SIZE ||
 695             blocksize > NILFS_MAX_BLOCK_SIZE) {
 696                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
 697                        "filesystem blocksize %d\n", blocksize);
 698                 err = -EINVAL;
 699                 goto failed_sbh;
 700         }
 701         if (sb->s_blocksize != blocksize) {
 702                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 703
 704                 if (blocksize < hw_blocksize) {
 705                         printk(KERN_ERR
 706                                "NILFS: blocksize %d too small for device "
 707                                "(sector-size = %d).\n",
 708                                blocksize, hw_blocksize);
 709                         err = -EINVAL;
 710                         goto failed_sbh;
 711                 }
 712                 nilfs_release_super_block(nilfs);
 713                 sb_set_blocksize(sb, blocksize);
 714
 715                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 716                 if (err)
 717                         goto out;
 718                         /* not failed_sbh; sbh is released automatically
 719                            when reloading fails. */
 720         }
 721         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 722         nilfs->ns_blocksize = blocksize;
 723
 724         err = nilfs_store_disk_layout(nilfs, sbp);
 725         if (err)
 726                 goto failed_sbh;
 727
 728         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 729
 730         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 731
 732         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 733         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 734
 735         err = nilfs_store_log_cursor(nilfs, sbp);
 736         if (err)
 737                 goto failed_sbh;
 738
 739         /* Initialize gcinode cache */
 740         err = nilfs_init_gccache(nilfs);
 741         if (err)
 742                 goto failed_sbh;
 743
 744         set_nilfs_init(nilfs);
 745         err = 0;
 746  out:
 747         up_write(&nilfs->ns_sem);
 748         return err;
 749
 750  failed_sbh:
 751         nilfs_release_super_block(nilfs);
 752         goto out;
 753 }
 754
 755 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 756                             size_t nsegs)
 757 {
 758         sector_t seg_start, seg_end;
 759         sector_t start = 0, nblocks = 0;
 760         unsigned int sects_per_block;
 761         __u64 *sn;
 762         int ret = 0;
 763
 764         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 765                 bdev_logical_block_size(nilfs->ns_bdev);
 766         for (sn = segnump; sn < segnump + nsegs; sn++) {
 767                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 768
 769                 if (!nblocks) {
 770                         start = seg_start;
 771                         nblocks = seg_end - seg_start + 1;
 772                 } else if (start + nblocks == seg_start) {
 773                         nblocks += seg_end - seg_start + 1;
 774                 } else {
 775                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 776                                                    start * sects_per_block,
 777                                                    nblocks * sects_per_block,
 778                                                    GFP_NOFS,
 779                                                    BLKDEV_IFL_WAIT |
 780                                                    BLKDEV_IFL_BARRIER);
 781                         if (ret < 0)
 782                                 return ret;
 783                         nblocks = 0;
 784                 }
 785         }
 786         if (nblocks)
 787                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 788                                            start * sects_per_block,
 789                                            nblocks * sects_per_block,
 790                                            GFP_NOFS,
 791                                           BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 792         return ret;
 793 }
 794
 795 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 796 {
 797         struct inode *dat = nilfs_dat_inode(nilfs);
 798         unsigned long ncleansegs;
 799
 800         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
 801         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 802         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
 803         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 804         return 0;
 805 }
 806
 807 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 808 {
 809         unsigned long ncleansegs, nincsegs;
 810
 811         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 812         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 813                 nilfs->ns_blocks_per_segment + 1;
 814
 815         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 816 }
 817
 818 /**
 819  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
 820  * @nilfs: nilfs object
 821  * @rw_mount: mount type (non-zero value for read/write mount)
 822  * @cno: checkpoint number (zero for read-only mount)
 823  *
 824  * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
 825  * @rw_mount and @cno (in case of snapshots) matched.  If no instance
 826  * was found, NULL is returned.  Although the super block instance can
 827  * be unmounted after this function returns, the nilfs_sb_info struct
 828  * is kept on memory until nilfs_put_sbinfo() is called.
 829  */
 830 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
 831                                         int rw_mount, __u64 cno)
 832 {
 833         struct nilfs_sb_info *sbi;
 834
 835         down_read(&nilfs->ns_super_sem);
 836         /*
 837          * The SNAPSHOT flag and sb->s_flags are supposed to be
 838          * protected with nilfs->ns_super_sem.
 839          */
 840         sbi = nilfs->ns_current;
 841         if (rw_mount) {
 842                 if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
 843                         goto found; /* read/write mount */
 844                 else
 845                         goto out;
 846         } else if (cno == 0) {
 847                 if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
 848                         goto found; /* read-only mount */
 849                 else
 850                         goto out;
 851         }
 852
 853         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 854                 if (nilfs_test_opt(sbi, SNAPSHOT) &&
 855                     sbi->s_snapshot_cno == cno)
 856                         goto found; /* snapshot mount */
 857         }
 858  out:
 859         up_read(&nilfs->ns_super_sem);
 860         return NULL;
 861
 862  found:
 863         atomic_inc(&sbi->s_count);
 864         up_read(&nilfs->ns_super_sem);
 865         return sbi;
 866 }
 867
 868 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
 869                                 int snapshot_mount)
 870 {
 871         struct nilfs_sb_info *sbi;
 872         int ret = 0;
 873
 874         down_read(&nilfs->ns_super_sem);
 875         if (cno == 0 || cno > nilfs->ns_cno)
 876                 goto out_unlock;
 877
 878         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
 879                 if (sbi->s_snapshot_cno == cno &&
 880                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
 881                                         /* exclude read-only mounts */
 882                         ret++;
 883                         break;
 884                 }
 885         }
 886         /* for protecting recent checkpoints */
 887         if (cno >= nilfs_last_cno(nilfs))
 888                 ret++;
 889
 890  out_unlock:
 891         up_read(&nilfs->ns_super_sem);
 892         return ret;
 893 }