fs/nilfs2/super.c

   1 /*
   2  * super.c - NILFS module and super block management.
   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  *  linux/fs/ext2/super.c
  24  *
  25  * Copyright (C) 1992, 1993, 1994, 1995
  26  * Remy Card (card@masi.ibp.fr)
  27  * Laboratoire MASI - Institut Blaise Pascal
  28  * Universite Pierre et Marie Curie (Paris VI)
  29  *
  30  *  from
  31  *
  32  *  linux/fs/minix/inode.c
  33  *
  34  *  Copyright (C) 1991, 1992  Linus Torvalds
  35  *
  36  *  Big-endian to little-endian byte-swapping/bitmaps by
  37  *        David S. Miller (davem@caip.rutgers.edu), 1995
  38  */
  39
  40 #include <linux/module.h>
  41 #include <linux/string.h>
  42 #include <linux/slab.h>
  43 #include <linux/init.h>
  44 #include <linux/blkdev.h>
  45 #include <linux/parser.h>
  46 #include <linux/random.h>
  47 #include <linux/crc32.h>
  48 #include <linux/smp_lock.h>
  49 #include <linux/vfs.h>
  50 #include <linux/writeback.h>
  51 #include <linux/kobject.h>
  52 #include <linux/exportfs.h>
  53 #include <linux/seq_file.h>
  54 #include <linux/mount.h>
  55 #include "nilfs.h"
  56 #include "mdt.h"
  57 #include "alloc.h"
  58 #include "page.h"
  59 #include "cpfile.h"
  60 #include "ifile.h"
  61 #include "dat.h"
  62 #include "segment.h"
  63 #include "segbuf.h"
  64
  65 MODULE_AUTHOR("NTT Corp.");
  66 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
  67                    "(NILFS)");
  68 MODULE_LICENSE("GPL");
  69
  70 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
  71
  72 /**
  73  * nilfs_error() - report failure condition on a filesystem
  74  *
  75  * nilfs_error() sets an ERROR_FS flag on the superblock as well as
  76  * reporting an error message.  It should be called when NILFS detects
  77  * incoherences or defects of meta data on disk.  As for sustainable
  78  * errors such as a single-shot I/O error, nilfs_warning() or the printk()
  79  * function should be used instead.
  80  *
  81  * The segment constructor must not call this function because it can
  82  * kill itself.
  83  */
  84 void nilfs_error(struct super_block *sb, const char *function,
  85                  const char *fmt, ...)
  86 {
  87         struct nilfs_sb_info *sbi = NILFS_SB(sb);
  88         va_list args;
  89
  90         va_start(args, fmt);
  91         printk(KERN_CRIT "NILFS error (device %s): %s: ", sb->s_id, function);
  92         vprintk(fmt, args);
  93         printk("\n");
  94         va_end(args);
  95
  96         if (!(sb->s_flags & MS_RDONLY)) {
  97                 struct the_nilfs *nilfs = sbi->s_nilfs;
  98
  99                 if (!nilfs_test_opt(sbi, ERRORS_CONT))
 100                         nilfs_detach_segment_constructor(sbi);
 101
 102                 down_write(&nilfs->ns_sem);
 103                 if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
 104                         nilfs->ns_mount_state |= NILFS_ERROR_FS;
 105                         nilfs->ns_sbp[0]->s_state |=
 106                                 cpu_to_le16(NILFS_ERROR_FS);
 107                         nilfs_commit_super(sbi, 1);
 108                 }
 109                 up_write(&nilfs->ns_sem);
 110
 111                 if (nilfs_test_opt(sbi, ERRORS_RO)) {
 112                         printk(KERN_CRIT "Remounting filesystem read-only\n");
 113                         sb->s_flags |= MS_RDONLY;
 114                 }
 115         }
 116
 117         if (nilfs_test_opt(sbi, ERRORS_PANIC))
 118                 panic("NILFS (device %s): panic forced after error\n",
 119                       sb->s_id);
 120 }
 121
 122 void nilfs_warning(struct super_block *sb, const char *function,
 123                    const char *fmt, ...)
 124 {
 125         va_list args;
 126
 127         va_start(args, fmt);
 128         printk(KERN_WARNING "NILFS warning (device %s): %s: ",
 129                sb->s_id, function);
 130         vprintk(fmt, args);
 131         printk("\n");
 132         va_end(args);
 133 }
 134
 135 static struct kmem_cache *nilfs_inode_cachep;
 136
 137 struct inode *nilfs_alloc_inode_common(struct the_nilfs *nilfs)
 138 {
 139         struct nilfs_inode_info *ii;
 140
 141         ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
 142         if (!ii)
 143                 return NULL;
 144         ii->i_bh = NULL;
 145         ii->i_state = 0;
 146         ii->vfs_inode.i_version = 1;
 147         nilfs_btnode_cache_init(&ii->i_btnode_cache, nilfs->ns_bdi);
 148         return &ii->vfs_inode;
 149 }
 150
 151 struct inode *nilfs_alloc_inode(struct super_block *sb)
 152 {
 153         return nilfs_alloc_inode_common(NILFS_SB(sb)->s_nilfs);
 154 }
 155
 156 void nilfs_destroy_inode(struct inode *inode)
 157 {
 158         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
 159 }
 160
 161 static void init_once(void *obj)
 162 {
 163         struct nilfs_inode_info *ii = obj;
 164
 165         INIT_LIST_HEAD(&ii->i_dirty);
 166 #ifdef CONFIG_NILFS_XATTR
 167         init_rwsem(&ii->xattr_sem);
 168 #endif
 169         nilfs_btnode_cache_init_once(&ii->i_btnode_cache);
 170         ii->i_bmap = (struct nilfs_bmap *)&ii->i_bmap_union;
 171         inode_init_once(&ii->vfs_inode);
 172 }
 173
 174 static int nilfs_init_inode_cache(void)
 175 {
 176         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
 177                                                sizeof(struct nilfs_inode_info),
 178                                                0, SLAB_RECLAIM_ACCOUNT,
 179                                                init_once);
 180
 181         return (nilfs_inode_cachep == NULL) ? -ENOMEM : 0;
 182 }
 183
 184 static inline void nilfs_destroy_inode_cache(void)
 185 {
 186         kmem_cache_destroy(nilfs_inode_cachep);
 187 }
 188
 189 static void nilfs_clear_inode(struct inode *inode)
 190 {
 191         struct nilfs_inode_info *ii = NILFS_I(inode);
 192
 193         /*
 194          * Free resources allocated in nilfs_read_inode(), here.
 195          */
 196         BUG_ON(!list_empty(&ii->i_dirty));
 197         brelse(ii->i_bh);
 198         ii->i_bh = NULL;
 199
 200         if (test_bit(NILFS_I_BMAP, &ii->i_state))
 201                 nilfs_bmap_clear(ii->i_bmap);
 202
 203         nilfs_btnode_cache_clear(&ii->i_btnode_cache);
 204 }
 205
 206 static int nilfs_sync_super(struct nilfs_sb_info *sbi, int dupsb)
 207 {
 208         struct the_nilfs *nilfs = sbi->s_nilfs;
 209         int err;
 210         int barrier_done = 0;
 211
 212         if (nilfs_test_opt(sbi, BARRIER)) {
 213                 set_buffer_ordered(nilfs->ns_sbh[0]);
 214                 barrier_done = 1;
 215         }
 216  retry:
 217         set_buffer_dirty(nilfs->ns_sbh[0]);
 218         err = sync_dirty_buffer(nilfs->ns_sbh[0]);
 219         if (err == -EOPNOTSUPP && barrier_done) {
 220                 nilfs_warning(sbi->s_super, __func__,
 221                               "barrier-based sync failed. "
 222                               "disabling barriers\n");
 223                 nilfs_clear_opt(sbi, BARRIER);
 224                 barrier_done = 0;
 225                 clear_buffer_ordered(nilfs->ns_sbh[0]);
 226                 goto retry;
 227         }
 228         if (unlikely(err)) {
 229                 printk(KERN_ERR
 230                        "NILFS: unable to write superblock (err=%d)\n", err);
 231                 if (err == -EIO && nilfs->ns_sbh[1]) {
 232                         nilfs_fall_back_super_block(nilfs);
 233                         goto retry;
 234                 }
 235         } else {
 236                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
 237
 238                 /*
 239                  * The latest segment becomes trailable from the position
 240                  * written in superblock.
 241                  */
 242                 clear_nilfs_discontinued(nilfs);
 243
 244                 /* update GC protection for recent segments */
 245                 if (nilfs->ns_sbh[1]) {
 246                         sbp = NULL;
 247                         if (dupsb) {
 248                                 set_buffer_dirty(nilfs->ns_sbh[1]);
 249                                 if (!sync_dirty_buffer(nilfs->ns_sbh[1]))
 250                                         sbp = nilfs->ns_sbp[1];
 251                         }
 252                 }
 253                 if (sbp) {
 254                         spin_lock(&nilfs->ns_last_segment_lock);
 255                         nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
 256                         spin_unlock(&nilfs->ns_last_segment_lock);
 257                 }
 258         }
 259
 260         return err;
 261 }
 262
 263 int nilfs_commit_super(struct nilfs_sb_info *sbi, int dupsb)
 264 {
 265         struct the_nilfs *nilfs = sbi->s_nilfs;
 266         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 267         sector_t nfreeblocks;
 268         time_t t;
 269         int err;
 270
 271         /* nilfs->sem must be locked by the caller. */
 272         if (sbp[0]->s_magic != NILFS_SUPER_MAGIC) {
 273                 if (sbp[1] && sbp[1]->s_magic == NILFS_SUPER_MAGIC)
 274                         nilfs_swap_super_block(nilfs);
 275                 else {
 276                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
 277                                sbi->s_super->s_id);
 278                         return -EIO;
 279                 }
 280         }
 281         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
 282         if (unlikely(err)) {
 283                 printk(KERN_ERR "NILFS: failed to count free blocks\n");
 284                 return err;
 285         }
 286         spin_lock(&nilfs->ns_last_segment_lock);
 287         sbp[0]->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
 288         sbp[0]->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
 289         sbp[0]->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
 290         spin_unlock(&nilfs->ns_last_segment_lock);
 291
 292         t = get_seconds();
 293         nilfs->ns_sbwtime[0] = t;
 294         sbp[0]->s_free_blocks_count = cpu_to_le64(nfreeblocks);
 295         sbp[0]->s_wtime = cpu_to_le64(t);
 296         sbp[0]->s_sum = 0;
 297         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
 298                                              (unsigned char *)sbp[0],
 299                                              nilfs->ns_sbsize));
 300         if (dupsb && sbp[1]) {
 301                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
 302                 nilfs->ns_sbwtime[1] = t;
 303         }
 304         sbi->s_super->s_dirt = 0;
 305         return nilfs_sync_super(sbi, dupsb);
 306 }
 307
 308 static void nilfs_put_super(struct super_block *sb)
 309 {
 310         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 311         struct the_nilfs *nilfs = sbi->s_nilfs;
 312
 313         lock_kernel();
 314
 315         nilfs_detach_segment_constructor(sbi);
 316
 317         if (!(sb->s_flags & MS_RDONLY)) {
 318                 down_write(&nilfs->ns_sem);
 319                 nilfs->ns_sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
 320                 nilfs_commit_super(sbi, 1);
 321                 up_write(&nilfs->ns_sem);
 322         }
 323         down_write(&nilfs->ns_super_sem);
 324         if (nilfs->ns_current == sbi)
 325                 nilfs->ns_current = NULL;
 326         up_write(&nilfs->ns_super_sem);
 327
 328         nilfs_detach_checkpoint(sbi);
 329         put_nilfs(sbi->s_nilfs);
 330         sbi->s_super = NULL;
 331         sb->s_fs_info = NULL;
 332         nilfs_put_sbinfo(sbi);
 333
 334         unlock_kernel();
 335 }
 336
 337 static int nilfs_sync_fs(struct super_block *sb, int wait)
 338 {
 339         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 340         struct the_nilfs *nilfs = sbi->s_nilfs;
 341         int err = 0;
 342
 343         /* This function is called when super block should be written back */
 344         if (wait)
 345                 err = nilfs_construct_segment(sb);
 346
 347         down_write(&nilfs->ns_sem);
 348         if (sb->s_dirt)
 349                 nilfs_commit_super(sbi, 1);
 350         up_write(&nilfs->ns_sem);
 351
 352         return err;
 353 }
 354
 355 int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
 356 {
 357         struct the_nilfs *nilfs = sbi->s_nilfs;
 358         struct nilfs_checkpoint *raw_cp;
 359         struct buffer_head *bh_cp;
 360         int err;
 361
 362         down_write(&nilfs->ns_super_sem);
 363         list_add(&sbi->s_list, &nilfs->ns_supers);
 364         up_write(&nilfs->ns_super_sem);
 365
 366         sbi->s_ifile = nilfs_ifile_new(sbi, nilfs->ns_inode_size);
 367         if (!sbi->s_ifile)
 368                 return -ENOMEM;
 369
 370         down_read(&nilfs->ns_segctor_sem);
 371         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
 372                                           &bh_cp);
 373         up_read(&nilfs->ns_segctor_sem);
 374         if (unlikely(err)) {
 375                 if (err == -ENOENT || err == -EINVAL) {
 376                         printk(KERN_ERR
 377                                "NILFS: Invalid checkpoint "
 378                                "(checkpoint number=%llu)\n",
 379                                (unsigned long long)cno);
 380                         err = -EINVAL;
 381                 }
 382                 goto failed;
 383         }
 384         err = nilfs_read_inode_common(sbi->s_ifile, &raw_cp->cp_ifile_inode);
 385         if (unlikely(err))
 386                 goto failed_bh;
 387         atomic_set(&sbi->s_inodes_count, le64_to_cpu(raw_cp->cp_inodes_count));
 388         atomic_set(&sbi->s_blocks_count, le64_to_cpu(raw_cp->cp_blocks_count));
 389
 390         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
 391         return 0;
 392
 393  failed_bh:
 394         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
 395  failed:
 396         nilfs_mdt_destroy(sbi->s_ifile);
 397         sbi->s_ifile = NULL;
 398
 399         down_write(&nilfs->ns_super_sem);
 400         list_del_init(&sbi->s_list);
 401         up_write(&nilfs->ns_super_sem);
 402
 403         return err;
 404 }
 405
 406 void nilfs_detach_checkpoint(struct nilfs_sb_info *sbi)
 407 {
 408         struct the_nilfs *nilfs = sbi->s_nilfs;
 409
 410         nilfs_mdt_destroy(sbi->s_ifile);
 411         sbi->s_ifile = NULL;
 412         down_write(&nilfs->ns_super_sem);
 413         list_del_init(&sbi->s_list);
 414         up_write(&nilfs->ns_super_sem);
 415 }
 416
 417 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 418 {
 419         struct super_block *sb = dentry->d_sb;
 420         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 421         struct the_nilfs *nilfs = sbi->s_nilfs;
 422         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 423         unsigned long long blocks;
 424         unsigned long overhead;
 425         unsigned long nrsvblocks;
 426         sector_t nfreeblocks;
 427         int err;
 428
 429         /*
 430          * Compute all of the segment blocks
 431          *
 432          * The blocks before first segment and after last segment
 433          * are excluded.
 434          */
 435         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
 436                 - nilfs->ns_first_data_block;
 437         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
 438
 439         /*
 440          * Compute the overhead
 441          *
 442          * When distributing meta data blocks outside semgent structure,
 443          * We must count them as the overhead.
 444          */
 445         overhead = 0;
 446
 447         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
 448         if (unlikely(err))
 449                 return err;
 450
 451         buf->f_type = NILFS_SUPER_MAGIC;
 452         buf->f_bsize = sb->s_blocksize;
 453         buf->f_blocks = blocks - overhead;
 454         buf->f_bfree = nfreeblocks;
 455         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
 456                 (buf->f_bfree - nrsvblocks) : 0;
 457         buf->f_files = atomic_read(&sbi->s_inodes_count);
 458         buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
 459         buf->f_namelen = NILFS_NAME_LEN;
 460         buf->f_fsid.val[0] = (u32)id;
 461         buf->f_fsid.val[1] = (u32)(id >> 32);
 462
 463         return 0;
 464 }
 465
 466 static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 467 {
 468         struct super_block *sb = vfs->mnt_sb;
 469         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 470
 471         if (!nilfs_test_opt(sbi, BARRIER))
 472                 seq_printf(seq, ",nobarrier");
 473         if (nilfs_test_opt(sbi, SNAPSHOT))
 474                 seq_printf(seq, ",cp=%llu",
 475                            (unsigned long long int)sbi->s_snapshot_cno);
 476         if (nilfs_test_opt(sbi, ERRORS_RO))
 477                 seq_printf(seq, ",errors=remount-ro");
 478         if (nilfs_test_opt(sbi, ERRORS_PANIC))
 479                 seq_printf(seq, ",errors=panic");
 480         if (nilfs_test_opt(sbi, STRICT_ORDER))
 481                 seq_printf(seq, ",order=strict");
 482         if (nilfs_test_opt(sbi, NORECOVERY))
 483                 seq_printf(seq, ",norecovery");
 484
 485         return 0;
 486 }
 487
 488 static const struct super_operations nilfs_sops = {
 489         .alloc_inode    = nilfs_alloc_inode,
 490         .destroy_inode  = nilfs_destroy_inode,
 491         .dirty_inode    = nilfs_dirty_inode,
 492         /* .write_inode    = nilfs_write_inode, */
 493         /* .put_inode      = nilfs_put_inode, */
 494         /* .drop_inode    = nilfs_drop_inode, */
 495         .delete_inode   = nilfs_delete_inode,
 496         .put_super      = nilfs_put_super,
 497         /* .write_super    = nilfs_write_super, */
 498         .sync_fs        = nilfs_sync_fs,
 499         /* .write_super_lockfs */
 500         /* .unlockfs */
 501         .statfs         = nilfs_statfs,
 502         .remount_fs     = nilfs_remount,
 503         .clear_inode    = nilfs_clear_inode,
 504         /* .umount_begin */
 505         .show_options = nilfs_show_options
 506 };
 507
 508 static struct inode *
 509 nilfs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation)
 510 {
 511         struct inode *inode;
 512
 513         if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO &&
 514             ino != NILFS_SKETCH_INO)
 515                 return ERR_PTR(-ESTALE);
 516
 517         inode = nilfs_iget(sb, ino);
 518         if (IS_ERR(inode))
 519                 return ERR_CAST(inode);
 520         if (generation && inode->i_generation != generation) {
 521                 iput(inode);
 522                 return ERR_PTR(-ESTALE);
 523         }
 524
 525         return inode;
 526 }
 527
 528 static struct dentry *
 529 nilfs_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len,
 530                    int fh_type)
 531 {
 532         return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
 533                                     nilfs_nfs_get_inode);
 534 }
 535
 536 static struct dentry *
 537 nilfs_fh_to_parent(struct super_block *sb, struct fid *fid, int fh_len,
 538                    int fh_type)
 539 {
 540         return generic_fh_to_parent(sb, fid, fh_len, fh_type,
 541                                     nilfs_nfs_get_inode);
 542 }
 543
 544 static const struct export_operations nilfs_export_ops = {
 545         .fh_to_dentry = nilfs_fh_to_dentry,
 546         .fh_to_parent = nilfs_fh_to_parent,
 547         .get_parent = nilfs_get_parent,
 548 };
 549
 550 enum {
 551         Opt_err_cont, Opt_err_panic, Opt_err_ro,
 552         Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
 553         Opt_err,
 554 };
 555
 556 static match_table_t tokens = {
 557         {Opt_err_cont, "errors=continue"},
 558         {Opt_err_panic, "errors=panic"},
 559         {Opt_err_ro, "errors=remount-ro"},
 560         {Opt_nobarrier, "nobarrier"},
 561         {Opt_snapshot, "cp=%u"},
 562         {Opt_order, "order=%s"},
 563         {Opt_norecovery, "norecovery"},
 564         {Opt_err, NULL}
 565 };
 566
 567 static int parse_options(char *options, struct super_block *sb)
 568 {
 569         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 570         char *p;
 571         substring_t args[MAX_OPT_ARGS];
 572         int option;
 573
 574         if (!options)
 575                 return 1;
 576
 577         while ((p = strsep(&options, ",")) != NULL) {
 578                 int token;
 579                 if (!*p)
 580                         continue;
 581
 582                 token = match_token(p, tokens, args);
 583                 switch (token) {
 584                 case Opt_nobarrier:
 585                         nilfs_clear_opt(sbi, BARRIER);
 586                         break;
 587                 case Opt_order:
 588                         if (strcmp(args[0].from, "relaxed") == 0)
 589                                 /* Ordered data semantics */
 590                                 nilfs_clear_opt(sbi, STRICT_ORDER);
 591                         else if (strcmp(args[0].from, "strict") == 0)
 592                                 /* Strict in-order semantics */
 593                                 nilfs_set_opt(sbi, STRICT_ORDER);
 594                         else
 595                                 return 0;
 596                         break;
 597                 case Opt_err_panic:
 598                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_PANIC);
 599                         break;
 600                 case Opt_err_ro:
 601                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_RO);
 602                         break;
 603                 case Opt_err_cont:
 604                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_CONT);
 605                         break;
 606                 case Opt_snapshot:
 607                         if (match_int(&args[0], &option) || option <= 0)
 608                                 return 0;
 609                         if (!(sb->s_flags & MS_RDONLY))
 610                                 return 0;
 611                         sbi->s_snapshot_cno = option;
 612                         nilfs_set_opt(sbi, SNAPSHOT);
 613                         break;
 614                 case Opt_norecovery:
 615                         nilfs_set_opt(sbi, NORECOVERY);
 616                         break;
 617                 default:
 618                         printk(KERN_ERR
 619                                "NILFS: Unrecognized mount option \"%s\"\n", p);
 620                         return 0;
 621                 }
 622         }
 623         return 1;
 624 }
 625
 626 static inline void
 627 nilfs_set_default_options(struct nilfs_sb_info *sbi,
 628                           struct nilfs_super_block *sbp)
 629 {
 630         sbi->s_mount_opt =
 631                 NILFS_MOUNT_ERRORS_CONT | NILFS_MOUNT_BARRIER;
 632 }
 633
 634 static int nilfs_setup_super(struct nilfs_sb_info *sbi)
 635 {
 636         struct the_nilfs *nilfs = sbi->s_nilfs;
 637         struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
 638         int max_mnt_count = le16_to_cpu(sbp->s_max_mnt_count);
 639         int mnt_count = le16_to_cpu(sbp->s_mnt_count);
 640
 641         /* nilfs->sem must be locked by the caller. */
 642         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
 643                 printk(KERN_WARNING
 644                        "NILFS warning: mounting fs with errors\n");
 645 #if 0
 646         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
 647                 printk(KERN_WARNING
 648                        "NILFS warning: maximal mount count reached\n");
 649 #endif
 650         }
 651         if (!max_mnt_count)
 652                 sbp->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
 653
 654         sbp->s_mnt_count = cpu_to_le16(mnt_count + 1);
 655         sbp->s_state = cpu_to_le16(le16_to_cpu(sbp->s_state) & ~NILFS_VALID_FS);
 656         sbp->s_mtime = cpu_to_le64(get_seconds());
 657         return nilfs_commit_super(sbi, 1);
 658 }
 659
 660 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
 661                                                  u64 pos, int blocksize,
 662                                                  struct buffer_head **pbh)
 663 {
 664         unsigned long long sb_index = pos;
 665         unsigned long offset;
 666
 667         offset = do_div(sb_index, blocksize);
 668         *pbh = sb_bread(sb, sb_index);
 669         if (!*pbh)
 670                 return NULL;
 671         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
 672 }
 673
 674 int nilfs_store_magic_and_option(struct super_block *sb,
 675                                  struct nilfs_super_block *sbp,
 676                                  char *data)
 677 {
 678         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 679
 680         sb->s_magic = le16_to_cpu(sbp->s_magic);
 681
 682         /* FS independent flags */
 683 #ifdef NILFS_ATIME_DISABLE
 684         sb->s_flags |= MS_NOATIME;
 685 #endif
 686
 687         nilfs_set_default_options(sbi, sbp);
 688
 689         sbi->s_resuid = le16_to_cpu(sbp->s_def_resuid);
 690         sbi->s_resgid = le16_to_cpu(sbp->s_def_resgid);
 691         sbi->s_interval = le32_to_cpu(sbp->s_c_interval);
 692         sbi->s_watermark = le32_to_cpu(sbp->s_c_block_max);
 693
 694         return !parse_options(data, sb) ? -EINVAL : 0 ;
 695 }
 696
 697 /**
 698  * nilfs_fill_super() - initialize a super block instance
 699  * @sb: super_block
 700  * @data: mount options
 701  * @silent: silent mode flag
 702  * @nilfs: the_nilfs struct
 703  *
 704  * This function is called exclusively by nilfs->ns_mount_mutex.
 705  * So, the recovery process is protected from other simultaneous mounts.
 706  */
 707 static int
 708 nilfs_fill_super(struct super_block *sb, void *data, int silent,
 709                  struct the_nilfs *nilfs)
 710 {
 711         struct nilfs_sb_info *sbi;
 712         struct inode *root;
 713         __u64 cno;
 714         int err;
 715
 716         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 717         if (!sbi)
 718                 return -ENOMEM;
 719
 720         sb->s_fs_info = sbi;
 721
 722         get_nilfs(nilfs);
 723         sbi->s_nilfs = nilfs;
 724         sbi->s_super = sb;
 725         atomic_set(&sbi->s_count, 1);
 726
 727         err = init_nilfs(nilfs, sbi, (char *)data);
 728         if (err)
 729                 goto failed_sbi;
 730
 731         spin_lock_init(&sbi->s_inode_lock);
 732         INIT_LIST_HEAD(&sbi->s_dirty_files);
 733         INIT_LIST_HEAD(&sbi->s_list);
 734
 735         /*
 736          * Following initialization is overlapped because
 737          * nilfs_sb_info structure has been cleared at the beginning.
 738          * But we reserve them to keep our interest and make ready
 739          * for the future change.
 740          */
 741         get_random_bytes(&sbi->s_next_generation,
 742                          sizeof(sbi->s_next_generation));
 743         spin_lock_init(&sbi->s_next_gen_lock);
 744
 745         sb->s_op = &nilfs_sops;
 746         sb->s_export_op = &nilfs_export_ops;
 747         sb->s_root = NULL;
 748         sb->s_time_gran = 1;
 749         sb->s_bdi = nilfs->ns_bdi;
 750
 751         err = load_nilfs(nilfs, sbi);
 752         if (err)
 753                 goto failed_sbi;
 754
 755         cno = nilfs_last_cno(nilfs);
 756
 757         if (sb->s_flags & MS_RDONLY) {
 758                 if (nilfs_test_opt(sbi, SNAPSHOT)) {
 759                         down_read(&nilfs->ns_segctor_sem);
 760                         err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
 761                                                        sbi->s_snapshot_cno);
 762                         up_read(&nilfs->ns_segctor_sem);
 763                         if (err < 0) {
 764                                 if (err == -ENOENT)
 765                                         err = -EINVAL;
 766                                 goto failed_sbi;
 767                         }
 768                         if (!err) {
 769                                 printk(KERN_ERR
 770                                        "NILFS: The specified checkpoint is "
 771                                        "not a snapshot "
 772                                        "(checkpoint number=%llu).\n",
 773                                        (unsigned long long)sbi->s_snapshot_cno);
 774                                 err = -EINVAL;
 775                                 goto failed_sbi;
 776                         }
 777                         cno = sbi->s_snapshot_cno;
 778                 } else
 779                         /* Read-only mount */
 780                         sbi->s_snapshot_cno = cno;
 781         }
 782
 783         err = nilfs_attach_checkpoint(sbi, cno);
 784         if (err) {
 785                 printk(KERN_ERR "NILFS: error loading a checkpoint"
 786                        " (checkpoint number=%llu).\n", (unsigned long long)cno);
 787                 goto failed_sbi;
 788         }
 789
 790         if (!(sb->s_flags & MS_RDONLY)) {
 791                 err = nilfs_attach_segment_constructor(sbi);
 792                 if (err)
 793                         goto failed_checkpoint;
 794         }
 795
 796         root = nilfs_iget(sb, NILFS_ROOT_INO);
 797         if (IS_ERR(root)) {
 798                 printk(KERN_ERR "NILFS: get root inode failed\n");
 799                 err = PTR_ERR(root);
 800                 goto failed_segctor;
 801         }
 802         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 803                 iput(root);
 804                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
 805                 err = -EINVAL;
 806                 goto failed_segctor;
 807         }
 808         sb->s_root = d_alloc_root(root);
 809         if (!sb->s_root) {
 810                 iput(root);
 811                 printk(KERN_ERR "NILFS: get root dentry failed\n");
 812                 err = -ENOMEM;
 813                 goto failed_segctor;
 814         }
 815
 816         if (!(sb->s_flags & MS_RDONLY)) {
 817                 down_write(&nilfs->ns_sem);
 818                 nilfs_setup_super(sbi);
 819                 up_write(&nilfs->ns_sem);
 820         }
 821
 822         down_write(&nilfs->ns_super_sem);
 823         if (!nilfs_test_opt(sbi, SNAPSHOT))
 824                 nilfs->ns_current = sbi;
 825         up_write(&nilfs->ns_super_sem);
 826
 827         return 0;
 828
 829  failed_segctor:
 830         nilfs_detach_segment_constructor(sbi);
 831
 832  failed_checkpoint:
 833         nilfs_detach_checkpoint(sbi);
 834
 835  failed_sbi:
 836         put_nilfs(nilfs);
 837         sb->s_fs_info = NULL;
 838         nilfs_put_sbinfo(sbi);
 839         return err;
 840 }
 841
 842 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
 843 {
 844         struct nilfs_sb_info *sbi = NILFS_SB(sb);
 845         struct nilfs_super_block *sbp;
 846         struct the_nilfs *nilfs = sbi->s_nilfs;
 847         unsigned long old_sb_flags;
 848         struct nilfs_mount_options old_opts;
 849         int err;
 850
 851         lock_kernel();
 852
 853         down_write(&nilfs->ns_super_sem);
 854         old_sb_flags = sb->s_flags;
 855         old_opts.mount_opt = sbi->s_mount_opt;
 856         old_opts.snapshot_cno = sbi->s_snapshot_cno;
 857
 858         if (!parse_options(data, sb)) {
 859                 err = -EINVAL;
 860                 goto restore_opts;
 861         }
 862         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
 863
 864         if ((*flags & MS_RDONLY) &&
 865             sbi->s_snapshot_cno != old_opts.snapshot_cno) {
 866                 printk(KERN_WARNING "NILFS (device %s): couldn't "
 867                        "remount to a different snapshot. \n",
 868                        sb->s_id);
 869                 err = -EINVAL;
 870                 goto restore_opts;
 871         }
 872
 873         if (!nilfs_valid_fs(nilfs)) {
 874                 printk(KERN_WARNING "NILFS (device %s): couldn't "
 875                        "remount because the filesystem is in an "
 876                        "incomplete recovery state.\n", sb->s_id);
 877                 err = -EINVAL;
 878                 goto restore_opts;
 879         }
 880
 881         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 882                 goto out;
 883         if (*flags & MS_RDONLY) {
 884                 /* Shutting down the segment constructor */
 885                 nilfs_detach_segment_constructor(sbi);
 886                 sb->s_flags |= MS_RDONLY;
 887
 888                 sbi->s_snapshot_cno = nilfs_last_cno(nilfs);
 889                 /* nilfs_set_opt(sbi, SNAPSHOT); */
 890
 891                 /*
 892                  * Remounting a valid RW partition RDONLY, so set
 893                  * the RDONLY flag and then mark the partition as valid again.
 894                  */
 895                 down_write(&nilfs->ns_sem);
 896                 sbp = nilfs->ns_sbp[0];
 897                 if (!(sbp->s_state & le16_to_cpu(NILFS_VALID_FS)) &&
 898                     (nilfs->ns_mount_state & NILFS_VALID_FS))
 899                         sbp->s_state = cpu_to_le16(nilfs->ns_mount_state);
 900                 sbp->s_mtime = cpu_to_le64(get_seconds());
 901                 nilfs_commit_super(sbi, 1);
 902                 up_write(&nilfs->ns_sem);
 903         } else {
 904                 /*
 905                  * Mounting a RDONLY partition read-write, so reread and
 906                  * store the current valid flag.  (It may have been changed
 907                  * by fsck since we originally mounted the partition.)
 908                  */
 909                 if (nilfs->ns_current && nilfs->ns_current != sbi) {
 910                         printk(KERN_WARNING "NILFS (device %s): couldn't "
 911                                "remount because an RW-mount exists.\n",
 912                                sb->s_id);
 913                         err = -EBUSY;
 914                         goto restore_opts;
 915                 }
 916                 if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
 917                         printk(KERN_WARNING "NILFS (device %s): couldn't "
 918                                "remount because the current RO-mount is not "
 919                                "the latest one.\n",
 920                                sb->s_id);
 921                         err = -EINVAL;
 922                         goto restore_opts;
 923                 }
 924                 sb->s_flags &= ~MS_RDONLY;
 925                 nilfs_clear_opt(sbi, SNAPSHOT);
 926                 sbi->s_snapshot_cno = 0;
 927
 928                 err = nilfs_attach_segment_constructor(sbi);
 929                 if (err)
 930                         goto restore_opts;
 931
 932                 down_write(&nilfs->ns_sem);
 933                 nilfs_setup_super(sbi);
 934                 up_write(&nilfs->ns_sem);
 935
 936                 nilfs->ns_current = sbi;
 937         }
 938  out:
 939         up_write(&nilfs->ns_super_sem);
 940         unlock_kernel();
 941         return 0;
 942
 943  restore_opts:
 944         sb->s_flags = old_sb_flags;
 945         sbi->s_mount_opt = old_opts.mount_opt;
 946         sbi->s_snapshot_cno = old_opts.snapshot_cno;
 947         up_write(&nilfs->ns_super_sem);
 948         unlock_kernel();
 949         return err;
 950 }
 951
 952 struct nilfs_super_data {
 953         struct block_device *bdev;
 954         struct nilfs_sb_info *sbi;
 955         __u64 cno;
 956         int flags;
 957 };
 958
 959 /**
 960  * nilfs_identify - pre-read mount options needed to identify mount instance
 961  * @data: mount options
 962  * @sd: nilfs_super_data
 963  */
 964 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
 965 {
 966         char *p, *options = data;
 967         substring_t args[MAX_OPT_ARGS];
 968         int option, token;
 969         int ret = 0;
 970
 971         do {
 972                 p = strsep(&options, ",");
 973                 if (p != NULL && *p) {
 974                         token = match_token(p, tokens, args);
 975                         if (token == Opt_snapshot) {
 976                                 if (!(sd->flags & MS_RDONLY))
 977                                         ret++;
 978                                 else {
 979                                         ret = match_int(&args[0], &option);
 980                                         if (!ret) {
 981                                                 if (option > 0)
 982                                                         sd->cno = option;
 983                                                 else
 984                                                         ret++;
 985                                         }
 986                                 }
 987                         }
 988                         if (ret)
 989                                 printk(KERN_ERR
 990                                        "NILFS: invalid mount option: %s\n", p);
 991                 }
 992                 if (!options)
 993                         break;
 994                 BUG_ON(options == data);
 995                 *(options - 1) = ',';
 996         } while (!ret);
 997         return ret;
 998 }
 999
1000 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1001 {
1002         struct nilfs_super_data *sd = data;
1003
1004         s->s_bdev = sd->bdev;
1005         s->s_dev = s->s_bdev->bd_dev;
1006         return 0;
1007 }
1008
1009 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1010 {
1011         struct nilfs_super_data *sd = data;
1012
1013         return sd->sbi && s->s_fs_info == (void *)sd->sbi;
1014 }
1015
1016 static int
1017 nilfs_get_sb(struct file_system_type *fs_type, int flags,
1018              const char *dev_name, void *data, struct vfsmount *mnt)
1019 {
1020         struct nilfs_super_data sd;
1021         struct super_block *s;
1022         struct the_nilfs *nilfs;
1023         int err, need_to_close = 1;
1024
1025         sd.bdev = open_bdev_exclusive(dev_name, flags, fs_type);
1026         if (IS_ERR(sd.bdev))
1027                 return PTR_ERR(sd.bdev);
1028
1029         /*
1030          * To get mount instance using sget() vfs-routine, NILFS needs
1031          * much more information than normal filesystems to identify mount
1032          * instance.  For snapshot mounts, not only a mount type (ro-mount
1033          * or rw-mount) but also a checkpoint number is required.
1034          */
1035         sd.cno = 0;
1036         sd.flags = flags;
1037         if (nilfs_identify((char *)data, &sd)) {
1038                 err = -EINVAL;
1039                 goto failed;
1040         }
1041
1042         nilfs = find_or_create_nilfs(sd.bdev);
1043         if (!nilfs) {
1044                 err = -ENOMEM;
1045                 goto failed;
1046         }
1047
1048         mutex_lock(&nilfs->ns_mount_mutex);
1049
1050         if (!sd.cno) {
1051                 /*
1052                  * Check if an exclusive mount exists or not.
1053                  * Snapshot mounts coexist with a current mount
1054                  * (i.e. rw-mount or ro-mount), whereas rw-mount and
1055                  * ro-mount are mutually exclusive.
1056                  */
1057                 down_read(&nilfs->ns_super_sem);
1058                 if (nilfs->ns_current &&
1059                     ((nilfs->ns_current->s_super->s_flags ^ flags)
1060                      & MS_RDONLY)) {
1061                         up_read(&nilfs->ns_super_sem);
1062                         err = -EBUSY;
1063                         goto failed_unlock;
1064                 }
1065                 up_read(&nilfs->ns_super_sem);
1066         }
1067
1068         /*
1069          * Find existing nilfs_sb_info struct
1070          */
1071         sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);
1072
1073         /*
1074          * Get super block instance holding the nilfs_sb_info struct.
1075          * A new instance is allocated if no existing mount is present or
1076          * existing instance has been unmounted.
1077          */
1078         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);
1079         if (sd.sbi)
1080                 nilfs_put_sbinfo(sd.sbi);
1081
1082         if (IS_ERR(s)) {
1083                 err = PTR_ERR(s);
1084                 goto failed_unlock;
1085         }
1086
1087         if (!s->s_root) {
1088                 char b[BDEVNAME_SIZE];
1089
1090                 /* New superblock instance created */
1091                 s->s_flags = flags;
1092                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1093                 sb_set_blocksize(s, block_size(sd.bdev));
1094
1095                 err = nilfs_fill_super(s, data, flags & MS_VERBOSE, nilfs);
1096                 if (err)
1097                         goto cancel_new;
1098
1099                 s->s_flags |= MS_ACTIVE;
1100                 need_to_close = 0;
1101         }
1102
1103         mutex_unlock(&nilfs->ns_mount_mutex);
1104         put_nilfs(nilfs);
1105         if (need_to_close)
1106                 close_bdev_exclusive(sd.bdev, flags);
1107         simple_set_mnt(mnt, s);
1108         return 0;
1109
1110  failed_unlock:
1111         mutex_unlock(&nilfs->ns_mount_mutex);
1112         put_nilfs(nilfs);
1113  failed:
1114         close_bdev_exclusive(sd.bdev, flags);
1115
1116         return err;
1117
1118  cancel_new:
1119         /* Abandoning the newly allocated superblock */
1120         mutex_unlock(&nilfs->ns_mount_mutex);
1121         put_nilfs(nilfs);
1122         deactivate_locked_super(s);
1123         /*
1124          * deactivate_super() invokes close_bdev_exclusive().
1125          * We must finish all post-cleaning before this call;
1126          * put_nilfs() needs the block device.
1127          */
1128         return err;
1129 }
1130
1131 struct file_system_type nilfs_fs_type = {
1132         .owner    = THIS_MODULE,
1133         .name     = "nilfs2",
1134         .get_sb   = nilfs_get_sb,
1135         .kill_sb  = kill_block_super,
1136         .fs_flags = FS_REQUIRES_DEV,
1137 };
1138
1139 static int __init init_nilfs_fs(void)
1140 {
1141         int err;
1142
1143         err = nilfs_init_inode_cache();
1144         if (err)
1145                 goto failed;
1146
1147         err = nilfs_init_transaction_cache();
1148         if (err)
1149                 goto failed_inode_cache;
1150
1151         err = nilfs_init_segbuf_cache();
1152         if (err)
1153                 goto failed_transaction_cache;
1154
1155         err = nilfs_btree_path_cache_init();
1156         if (err)
1157                 goto failed_segbuf_cache;
1158
1159         err = register_filesystem(&nilfs_fs_type);
1160         if (err)
1161                 goto failed_btree_path_cache;
1162
1163         return 0;
1164
1165  failed_btree_path_cache:
1166         nilfs_btree_path_cache_destroy();
1167
1168  failed_segbuf_cache:
1169         nilfs_destroy_segbuf_cache();
1170
1171  failed_transaction_cache:
1172         nilfs_destroy_transaction_cache();
1173
1174  failed_inode_cache:
1175         nilfs_destroy_inode_cache();
1176
1177  failed:
1178         return err;
1179 }
1180
1181 static void __exit exit_nilfs_fs(void)
1182 {
1183         nilfs_destroy_segbuf_cache();
1184         nilfs_destroy_transaction_cache();
1185         nilfs_destroy_inode_cache();
1186         nilfs_btree_path_cache_destroy();
1187         unregister_filesystem(&nilfs_fs_type);
1188 }
1189
1190 module_init(init_nilfs_fs)
1191 module_exit(exit_nilfs_fs)