kernel/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/random.h>
  29 #include <linux/crc32.h>
  30 #include "nilfs.h"
  31 #include "segment.h"
  32 #include "alloc.h"
  33 #include "cpfile.h"
  34 #include "sufile.h"
  35 #include "dat.h"
  36 #include "segbuf.h"
  37
  38
  39 static int nilfs_valid_sb(struct nilfs_super_block *sbp);
  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
  49         if (!nilfs_sb_dirty(nilfs)) {
  50                 if (nilfs->ns_prev_seq == nilfs->ns_last_seq)
  51                         goto stay_cursor;
  52
  53                 set_nilfs_sb_dirty(nilfs);
  54         }
  55         nilfs->ns_prev_seq = nilfs->ns_last_seq;
  56
  57  stay_cursor:
  58         spin_unlock(&nilfs->ns_last_segment_lock);
  59 }
  60
  61 /**
  62  * alloc_nilfs - allocate a nilfs object
  63  * @bdev: block device to which the_nilfs is related
  64  *
  65  * Return Value: On success, pointer to the_nilfs is returned.
  66  * On error, NULL is returned.
  67  */
  68 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
  69 {
  70         struct the_nilfs *nilfs;
  71
  72         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
  73         if (!nilfs)
  74                 return NULL;
  75
  76         nilfs->ns_bdev = bdev;
  77         atomic_set(&nilfs->ns_ndirtyblks, 0);
  78         init_rwsem(&nilfs->ns_sem);
  79         mutex_init(&nilfs->ns_snapshot_mount_mutex);
  80         INIT_LIST_HEAD(&nilfs->ns_dirty_files);
  81         INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
  82         spin_lock_init(&nilfs->ns_inode_lock);
  83         spin_lock_init(&nilfs->ns_next_gen_lock);
  84         spin_lock_init(&nilfs->ns_last_segment_lock);
  85         nilfs->ns_cptree = RB_ROOT;
  86         spin_lock_init(&nilfs->ns_cptree_lock);
  87         init_rwsem(&nilfs->ns_segctor_sem);
  88         nilfs->ns_sb_update_freq = NILFS_SB_FREQ;
  89
  90         return nilfs;
  91 }
  92
  93 /**
  94  * destroy_nilfs - destroy nilfs object
  95  * @nilfs: nilfs object to be released
  96  */
  97 void destroy_nilfs(struct the_nilfs *nilfs)
  98 {
  99         might_sleep();
 100         if (nilfs_init(nilfs)) {
 101                 nilfs_sysfs_delete_device_group(nilfs);
 102                 brelse(nilfs->ns_sbh[0]);
 103                 brelse(nilfs->ns_sbh[1]);
 104         }
 105         kfree(nilfs);
 106 }
 107
 108 static int nilfs_load_super_root(struct the_nilfs *nilfs,
 109                                  struct super_block *sb, sector_t sr_block)
 110 {
 111         struct buffer_head *bh_sr;
 112         struct nilfs_super_root *raw_sr;
 113         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 114         struct nilfs_inode *rawi;
 115         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
 116         unsigned inode_size;
 117         int err;
 118
 119         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
 120         if (unlikely(err))
 121                 return err;
 122
 123         down_read(&nilfs->ns_sem);
 124         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
 125         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
 126         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
 127         up_read(&nilfs->ns_sem);
 128
 129         inode_size = nilfs->ns_inode_size;
 130
 131         rawi = (void *)bh_sr->b_data + NILFS_SR_DAT_OFFSET(inode_size);
 132         err = nilfs_dat_read(sb, dat_entry_size, rawi, &nilfs->ns_dat);
 133         if (err)
 134                 goto failed;
 135
 136         rawi = (void *)bh_sr->b_data + NILFS_SR_CPFILE_OFFSET(inode_size);
 137         err = nilfs_cpfile_read(sb, checkpoint_size, rawi, &nilfs->ns_cpfile);
 138         if (err)
 139                 goto failed_dat;
 140
 141         rawi = (void *)bh_sr->b_data + NILFS_SR_SUFILE_OFFSET(inode_size);
 142         err = nilfs_sufile_read(sb, segment_usage_size, rawi,
 143                                 &nilfs->ns_sufile);
 144         if (err)
 145                 goto failed_cpfile;
 146
 147         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
 148         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
 149
 150  failed:
 151         brelse(bh_sr);
 152         return err;
 153
 154  failed_cpfile:
 155         iput(nilfs->ns_cpfile);
 156
 157  failed_dat:
 158         iput(nilfs->ns_dat);
 159         goto failed;
 160 }
 161
 162 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
 163 {
 164         memset(ri, 0, sizeof(*ri));
 165         INIT_LIST_HEAD(&ri->ri_used_segments);
 166 }
 167
 168 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
 169 {
 170         nilfs_dispose_segment_list(&ri->ri_used_segments);
 171 }
 172
 173 /**
 174  * nilfs_store_log_cursor - load log cursor from a super block
 175  * @nilfs: nilfs object
 176  * @sbp: buffer storing super block to be read
 177  *
 178  * nilfs_store_log_cursor() reads the last position of the log
 179  * containing a super root from a given super block, and initializes
 180  * relevant information on the nilfs object preparatory for log
 181  * scanning and recovery.
 182  */
 183 static int nilfs_store_log_cursor(struct the_nilfs *nilfs,
 184                                   struct nilfs_super_block *sbp)
 185 {
 186         int ret = 0;
 187
 188         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
 189         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
 190         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
 191
 192         nilfs->ns_prev_seq = nilfs->ns_last_seq;
 193         nilfs->ns_seg_seq = nilfs->ns_last_seq;
 194         nilfs->ns_segnum =
 195                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
 196         nilfs->ns_cno = nilfs->ns_last_cno + 1;
 197         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
 198                 printk(KERN_ERR "NILFS invalid last segment number.\n");
 199                 ret = -EINVAL;
 200         }
 201         return ret;
 202 }
 203
 204 /**
 205  * load_nilfs - load and recover the nilfs
 206  * @nilfs: the_nilfs structure to be released
 207  * @sb: super block isntance used to recover past segment
 208  *
 209  * load_nilfs() searches and load the latest super root,
 210  * attaches the last segment, and does recovery if needed.
 211  * The caller must call this exclusively for simultaneous mounts.
 212  */
 213 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb)
 214 {
 215         struct nilfs_recovery_info ri;
 216         unsigned int s_flags = sb->s_flags;
 217         int really_read_only = bdev_read_only(nilfs->ns_bdev);
 218         int valid_fs = nilfs_valid_fs(nilfs);
 219         int err;
 220
 221         if (!valid_fs) {
 222                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
 223                 if (s_flags & MS_RDONLY) {
 224                         printk(KERN_INFO "NILFS: INFO: recovery "
 225                                "required for readonly filesystem.\n");
 226                         printk(KERN_INFO "NILFS: write access will "
 227                                "be enabled during recovery.\n");
 228                 }
 229         }
 230
 231         nilfs_init_recovery_info(&ri);
 232
 233         err = nilfs_search_super_root(nilfs, &ri);
 234         if (unlikely(err)) {
 235                 struct nilfs_super_block **sbp = nilfs->ns_sbp;
 236                 int blocksize;
 237
 238                 if (err != -EINVAL)
 239                         goto scan_error;
 240
 241                 if (!nilfs_valid_sb(sbp[1])) {
 242                         printk(KERN_WARNING
 243                                "NILFS warning: unable to fall back to spare"
 244                                "super block\n");
 245                         goto scan_error;
 246                 }
 247                 printk(KERN_INFO
 248                        "NILFS: try rollback from an earlier position\n");
 249
 250                 /*
 251                  * restore super block with its spare and reconfigure
 252                  * relevant states of the nilfs object.
 253                  */
 254                 memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 255                 nilfs->ns_crc_seed = le32_to_cpu(sbp[0]->s_crc_seed);
 256                 nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 257
 258                 /* verify consistency between two super blocks */
 259                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp[0]->s_log_block_size);
 260                 if (blocksize != nilfs->ns_blocksize) {
 261                         printk(KERN_WARNING
 262                                "NILFS warning: blocksize differs between "
 263                                "two super blocks (%d != %d)\n",
 264                                blocksize, nilfs->ns_blocksize);
 265                         goto scan_error;
 266                 }
 267
 268                 err = nilfs_store_log_cursor(nilfs, sbp[0]);
 269                 if (err)
 270                         goto scan_error;
 271
 272                 /* drop clean flag to allow roll-forward and recovery */
 273                 nilfs->ns_mount_state &= ~NILFS_VALID_FS;
 274                 valid_fs = 0;
 275
 276                 err = nilfs_search_super_root(nilfs, &ri);
 277                 if (err)
 278                         goto scan_error;
 279         }
 280
 281         err = nilfs_load_super_root(nilfs, sb, ri.ri_super_root);
 282         if (unlikely(err)) {
 283                 printk(KERN_ERR "NILFS: error loading super root.\n");
 284                 goto failed;
 285         }
 286
 287         if (valid_fs)
 288                 goto skip_recovery;
 289
 290         if (s_flags & MS_RDONLY) {
 291                 __u64 features;
 292
 293                 if (nilfs_test_opt(nilfs, NORECOVERY)) {
 294                         printk(KERN_INFO "NILFS: norecovery option specified. "
 295                                "skipping roll-forward recovery\n");
 296                         goto skip_recovery;
 297                 }
 298                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
 299                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
 300                 if (features) {
 301                         printk(KERN_ERR "NILFS: couldn't proceed with "
 302                                "recovery because of unsupported optional "
 303                                "features (%llx)\n",
 304                                (unsigned long long)features);
 305                         err = -EROFS;
 306                         goto failed_unload;
 307                 }
 308                 if (really_read_only) {
 309                         printk(KERN_ERR "NILFS: write access "
 310                                "unavailable, cannot proceed.\n");
 311                         err = -EROFS;
 312                         goto failed_unload;
 313                 }
 314                 sb->s_flags &= ~MS_RDONLY;
 315         } else if (nilfs_test_opt(nilfs, NORECOVERY)) {
 316                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
 317                        "option was specified for a read/write mount\n");
 318                 err = -EINVAL;
 319                 goto failed_unload;
 320         }
 321
 322         err = nilfs_salvage_orphan_logs(nilfs, sb, &ri);
 323         if (err)
 324                 goto failed_unload;
 325
 326         down_write(&nilfs->ns_sem);
 327         nilfs->ns_mount_state |= NILFS_VALID_FS; /* set "clean" flag */
 328         err = nilfs_cleanup_super(sb);
 329         up_write(&nilfs->ns_sem);
 330
 331         if (err) {
 332                 printk(KERN_ERR "NILFS: failed to update super block. "
 333                        "recovery unfinished.\n");
 334                 goto failed_unload;
 335         }
 336         printk(KERN_INFO "NILFS: recovery complete.\n");
 337
 338  skip_recovery:
 339         nilfs_clear_recovery_info(&ri);
 340         sb->s_flags = s_flags;
 341         return 0;
 342
 343  scan_error:
 344         printk(KERN_ERR "NILFS: error searching super root.\n");
 345         goto failed;
 346
 347  failed_unload:
 348         iput(nilfs->ns_cpfile);
 349         iput(nilfs->ns_sufile);
 350         iput(nilfs->ns_dat);
 351
 352  failed:
 353         nilfs_clear_recovery_info(&ri);
 354         sb->s_flags = s_flags;
 355         return err;
 356 }
 357
 358 static unsigned long long nilfs_max_size(unsigned int blkbits)
 359 {
 360         unsigned int max_bits;
 361         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
 362
 363         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
 364         if (max_bits < 64)
 365                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
 366         return res;
 367 }
 368
 369 /**
 370  * nilfs_nrsvsegs - calculate the number of reserved segments
 371  * @nilfs: nilfs object
 372  * @nsegs: total number of segments
 373  */
 374 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs)
 375 {
 376         return max_t(unsigned long, NILFS_MIN_NRSVSEGS,
 377                      DIV_ROUND_UP(nsegs * nilfs->ns_r_segments_percentage,
 378                                   100));
 379 }
 380
 381 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs)
 382 {
 383         nilfs->ns_nsegments = nsegs;
 384         nilfs->ns_nrsvsegs = nilfs_nrsvsegs(nilfs, nsegs);
 385 }
 386
 387 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 388                                    struct nilfs_super_block *sbp)
 389 {
 390         if (le32_to_cpu(sbp->s_rev_level) < NILFS_MIN_SUPP_REV) {
 391                 printk(KERN_ERR "NILFS: unsupported revision "
 392                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
 393                        "Please check the version of mkfs.nilfs.\n",
 394                        le32_to_cpu(sbp->s_rev_level),
 395                        le16_to_cpu(sbp->s_minor_rev_level),
 396                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
 397                 return -EINVAL;
 398         }
 399         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
 400         if (nilfs->ns_sbsize > BLOCK_SIZE)
 401                 return -EINVAL;
 402
 403         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
 404         if (nilfs->ns_inode_size > nilfs->ns_blocksize) {
 405                 printk(KERN_ERR "NILFS: too large inode size: %d bytes.\n",
 406                        nilfs->ns_inode_size);
 407                 return -EINVAL;
 408         } else if (nilfs->ns_inode_size < NILFS_MIN_INODE_SIZE) {
 409                 printk(KERN_ERR "NILFS: too small inode size: %d bytes.\n",
 410                        nilfs->ns_inode_size);
 411                 return -EINVAL;
 412         }
 413
 414         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
 415
 416         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
 417         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
 418                 printk(KERN_ERR "NILFS: too short segment.\n");
 419                 return -EINVAL;
 420         }
 421
 422         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 423         nilfs->ns_r_segments_percentage =
 424                 le32_to_cpu(sbp->s_r_segments_percentage);
 425         if (nilfs->ns_r_segments_percentage < 1 ||
 426             nilfs->ns_r_segments_percentage > 99) {
 427                 printk(KERN_ERR "NILFS: invalid reserved segments percentage.\n");
 428                 return -EINVAL;
 429         }
 430
 431         nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments));
 432         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 433         return 0;
 434 }
 435
 436 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
 437 {
 438         static unsigned char sum[4];
 439         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
 440         size_t bytes;
 441         u32 crc;
 442
 443         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
 444                 return 0;
 445         bytes = le16_to_cpu(sbp->s_bytes);
 446         if (bytes > BLOCK_SIZE)
 447                 return 0;
 448         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
 449                        sumoff);
 450         crc = crc32_le(crc, sum, 4);
 451         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
 452                        bytes - sumoff - 4);
 453         return crc == le32_to_cpu(sbp->s_sum);
 454 }
 455
 456 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
 457 {
 458         return offset < ((le64_to_cpu(sbp->s_nsegments) *
 459                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
 460                          (le32_to_cpu(sbp->s_log_block_size) + 10));
 461 }
 462
 463 static void nilfs_release_super_block(struct the_nilfs *nilfs)
 464 {
 465         int i;
 466
 467         for (i = 0; i < 2; i++) {
 468                 if (nilfs->ns_sbp[i]) {
 469                         brelse(nilfs->ns_sbh[i]);
 470                         nilfs->ns_sbh[i] = NULL;
 471                         nilfs->ns_sbp[i] = NULL;
 472                 }
 473         }
 474 }
 475
 476 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
 477 {
 478         brelse(nilfs->ns_sbh[0]);
 479         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 480         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 481         nilfs->ns_sbh[1] = NULL;
 482         nilfs->ns_sbp[1] = NULL;
 483 }
 484
 485 void nilfs_swap_super_block(struct the_nilfs *nilfs)
 486 {
 487         struct buffer_head *tsbh = nilfs->ns_sbh[0];
 488         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
 489
 490         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
 491         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
 492         nilfs->ns_sbh[1] = tsbh;
 493         nilfs->ns_sbp[1] = tsbp;
 494 }
 495
 496 static int nilfs_load_super_block(struct the_nilfs *nilfs,
 497                                   struct super_block *sb, int blocksize,
 498                                   struct nilfs_super_block **sbpp)
 499 {
 500         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 501         struct buffer_head **sbh = nilfs->ns_sbh;
 502         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
 503         int valid[2], swp = 0;
 504
 505         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 506                                         &sbh[0]);
 507         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
 508
 509         if (!sbp[0]) {
 510                 if (!sbp[1]) {
 511                         printk(KERN_ERR "NILFS: unable to read superblock\n");
 512                         return -EIO;
 513                 }
 514                 printk(KERN_WARNING
 515                        "NILFS warning: unable to read primary superblock "
 516                        "(blocksize = %d)\n", blocksize);
 517         } else if (!sbp[1]) {
 518                 printk(KERN_WARNING
 519                        "NILFS warning: unable to read secondary superblock "
 520                        "(blocksize = %d)\n", blocksize);
 521         }
 522
 523         /*
 524          * Compare two super blocks and set 1 in swp if the secondary
 525          * super block is valid and newer.  Otherwise, set 0 in swp.
 526          */
 527         valid[0] = nilfs_valid_sb(sbp[0]);
 528         valid[1] = nilfs_valid_sb(sbp[1]);
 529         swp = valid[1] && (!valid[0] ||
 530                            le64_to_cpu(sbp[1]->s_last_cno) >
 531                            le64_to_cpu(sbp[0]->s_last_cno));
 532
 533         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 534                 brelse(sbh[1]);
 535                 sbh[1] = NULL;
 536                 sbp[1] = NULL;
 537                 valid[1] = 0;
 538                 swp = 0;
 539         }
 540         if (!valid[swp]) {
 541                 nilfs_release_super_block(nilfs);
 542                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
 543                        sb->s_id);
 544                 return -EINVAL;
 545         }
 546
 547         if (!valid[!swp])
 548                 printk(KERN_WARNING "NILFS warning: broken superblock. "
 549                        "using spare superblock (blocksize = %d).\n", blocksize);
 550         if (swp)
 551                 nilfs_swap_super_block(nilfs);
 552
 553         nilfs->ns_sbwcount = 0;
 554         nilfs->ns_sbwtime = le64_to_cpu(sbp[0]->s_wtime);
 555         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
 556         *sbpp = sbp[0];
 557         return 0;
 558 }
 559
 560 /**
 561  * init_nilfs - initialize a NILFS instance.
 562  * @nilfs: the_nilfs structure
 563  * @sb: super block
 564  * @data: mount options
 565  *
 566  * init_nilfs() performs common initialization per block device (e.g.
 567  * reading the super block, getting disk layout information, initializing
 568  * shared fields in the_nilfs).
 569  *
 570  * Return Value: On success, 0 is returned. On error, a negative error
 571  * code is returned.
 572  */
 573 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data)
 574 {
 575         struct nilfs_super_block *sbp;
 576         int blocksize;
 577         int err;
 578
 579         down_write(&nilfs->ns_sem);
 580
 581         blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
 582         if (!blocksize) {
 583                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
 584                 err = -EINVAL;
 585                 goto out;
 586         }
 587         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 588         if (err)
 589                 goto out;
 590
 591         err = nilfs_store_magic_and_option(sb, sbp, data);
 592         if (err)
 593                 goto failed_sbh;
 594
 595         err = nilfs_check_feature_compatibility(sb, sbp);
 596         if (err)
 597                 goto failed_sbh;
 598
 599         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
 600         if (blocksize < NILFS_MIN_BLOCK_SIZE ||
 601             blocksize > NILFS_MAX_BLOCK_SIZE) {
 602                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
 603                        "filesystem blocksize %d\n", blocksize);
 604                 err = -EINVAL;
 605                 goto failed_sbh;
 606         }
 607         if (sb->s_blocksize != blocksize) {
 608                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 609
 610                 if (blocksize < hw_blocksize) {
 611                         printk(KERN_ERR
 612                                "NILFS: blocksize %d too small for device "
 613                                "(sector-size = %d).\n",
 614                                blocksize, hw_blocksize);
 615                         err = -EINVAL;
 616                         goto failed_sbh;
 617                 }
 618                 nilfs_release_super_block(nilfs);
 619                 sb_set_blocksize(sb, blocksize);
 620
 621                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
 622                 if (err)
 623                         goto out;
 624                         /* not failed_sbh; sbh is released automatically
 625                            when reloading fails. */
 626         }
 627         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
 628         nilfs->ns_blocksize = blocksize;
 629
 630         get_random_bytes(&nilfs->ns_next_generation,
 631                          sizeof(nilfs->ns_next_generation));
 632
 633         err = nilfs_store_disk_layout(nilfs, sbp);
 634         if (err)
 635                 goto failed_sbh;
 636
 637         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
 638
 639         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 640
 641         err = nilfs_store_log_cursor(nilfs, sbp);
 642         if (err)
 643                 goto failed_sbh;
 644
 645         err = nilfs_sysfs_create_device_group(sb);
 646         if (err)
 647                 goto failed_sbh;
 648
 649         set_nilfs_init(nilfs);
 650         err = 0;
 651  out:
 652         up_write(&nilfs->ns_sem);
 653         return err;
 654
 655  failed_sbh:
 656         nilfs_release_super_block(nilfs);
 657         goto out;
 658 }
 659
 660 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
 661                             size_t nsegs)
 662 {
 663         sector_t seg_start, seg_end;
 664         sector_t start = 0, nblocks = 0;
 665         unsigned int sects_per_block;
 666         __u64 *sn;
 667         int ret = 0;
 668
 669         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
 670                 bdev_logical_block_size(nilfs->ns_bdev);
 671         for (sn = segnump; sn < segnump + nsegs; sn++) {
 672                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
 673
 674                 if (!nblocks) {
 675                         start = seg_start;
 676                         nblocks = seg_end - seg_start + 1;
 677                 } else if (start + nblocks == seg_start) {
 678                         nblocks += seg_end - seg_start + 1;
 679                 } else {
 680                         ret = blkdev_issue_discard(nilfs->ns_bdev,
 681                                                    start * sects_per_block,
 682                                                    nblocks * sects_per_block,
 683                                                    GFP_NOFS, 0);
 684                         if (ret < 0)
 685                                 return ret;
 686                         nblocks = 0;
 687                 }
 688         }
 689         if (nblocks)
 690                 ret = blkdev_issue_discard(nilfs->ns_bdev,
 691                                            start * sects_per_block,
 692                                            nblocks * sects_per_block,
 693                                            GFP_NOFS, 0);
 694         return ret;
 695 }
 696
 697 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 698 {
 699         unsigned long ncleansegs;
 700
 701         down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
 702         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 703         up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
 704         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
 705         return 0;
 706 }
 707
 708 int nilfs_near_disk_full(struct the_nilfs *nilfs)
 709 {
 710         unsigned long ncleansegs, nincsegs;
 711
 712         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
 713         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
 714                 nilfs->ns_blocks_per_segment + 1;
 715
 716         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
 717 }
 718
 719 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
 720 {
 721         struct rb_node *n;
 722         struct nilfs_root *root;
 723
 724         spin_lock(&nilfs->ns_cptree_lock);
 725         n = nilfs->ns_cptree.rb_node;
 726         while (n) {
 727                 root = rb_entry(n, struct nilfs_root, rb_node);
 728
 729                 if (cno < root->cno) {
 730                         n = n->rb_left;
 731                 } else if (cno > root->cno) {
 732                         n = n->rb_right;
 733                 } else {
 734                         atomic_inc(&root->count);
 735                         spin_unlock(&nilfs->ns_cptree_lock);
 736                         return root;
 737                 }
 738         }
 739         spin_unlock(&nilfs->ns_cptree_lock);
 740
 741         return NULL;
 742 }
 743
 744 struct nilfs_root *
 745 nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
 746 {
 747         struct rb_node **p, *parent;
 748         struct nilfs_root *root, *new;
 749         int err;
 750
 751         root = nilfs_lookup_root(nilfs, cno);
 752         if (root)
 753                 return root;
 754
 755         new = kzalloc(sizeof(*root), GFP_KERNEL);
 756         if (!new)
 757                 return NULL;
 758
 759         spin_lock(&nilfs->ns_cptree_lock);
 760
 761         p = &nilfs->ns_cptree.rb_node;
 762         parent = NULL;
 763
 764         while (*p) {
 765                 parent = *p;
 766                 root = rb_entry(parent, struct nilfs_root, rb_node);
 767
 768                 if (cno < root->cno) {
 769                         p = &(*p)->rb_left;
 770                 } else if (cno > root->cno) {
 771                         p = &(*p)->rb_right;
 772                 } else {
 773                         atomic_inc(&root->count);
 774                         spin_unlock(&nilfs->ns_cptree_lock);
 775                         kfree(new);
 776                         return root;
 777                 }
 778         }
 779
 780         new->cno = cno;
 781         new->ifile = NULL;
 782         new->nilfs = nilfs;
 783         atomic_set(&new->count, 1);
 784         atomic64_set(&new->inodes_count, 0);
 785         atomic64_set(&new->blocks_count, 0);
 786
 787         rb_link_node(&new->rb_node, parent, p);
 788         rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
 789
 790         spin_unlock(&nilfs->ns_cptree_lock);
 791
 792         err = nilfs_sysfs_create_snapshot_group(new);
 793         if (err) {
 794                 kfree(new);
 795                 new = NULL;
 796         }
 797
 798         return new;
 799 }
 800
 801 void nilfs_put_root(struct nilfs_root *root)
 802 {
 803         if (atomic_dec_and_test(&root->count)) {
 804                 struct the_nilfs *nilfs = root->nilfs;
 805
 806                 nilfs_sysfs_delete_snapshot_group(root);
 807
 808                 spin_lock(&nilfs->ns_cptree_lock);
 809                 rb_erase(&root->rb_node, &nilfs->ns_cptree);
 810                 spin_unlock(&nilfs->ns_cptree_lock);
 811                 iput(root->ifile);
 812
 813                 kfree(root);
 814         }
 815 }