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/crc32.h>
  47 #include <linux/vfs.h>
  48 #include <linux/writeback.h>
  49 #include <linux/seq_file.h>
  50 #include <linux/mount.h>
  51 #include "nilfs.h"
  52 #include "export.h"
  53 #include "mdt.h"
  54 #include "alloc.h"
  55 #include "btree.h"
  56 #include "btnode.h"
  57 #include "page.h"
  58 #include "cpfile.h"
  59 #include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
  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 struct kmem_cache *nilfs_inode_cachep;
  71 struct kmem_cache *nilfs_transaction_cachep;
  72 struct kmem_cache *nilfs_segbuf_cachep;
  73 struct kmem_cache *nilfs_btree_path_cache;
  74
  75 static int nilfs_setup_super(struct super_block *sb, int is_mount);
  76 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
  77
  78 static void nilfs_set_error(struct super_block *sb)
  79 {
  80         struct the_nilfs *nilfs = sb->s_fs_info;
  81         struct nilfs_super_block **sbp;
  82
  83         down_write(&nilfs->ns_sem);
  84         if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
  85                 nilfs->ns_mount_state |= NILFS_ERROR_FS;
  86                 sbp = nilfs_prepare_super(sb, 0);
  87                 if (likely(sbp)) {
  88                         sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
  89                         if (sbp[1])
  90                                 sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
  91                         nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
  92                 }
  93         }
  94         up_write(&nilfs->ns_sem);
  95 }
  96
  97 /**
  98  * nilfs_error() - report failure condition on a filesystem
  99  *
 100  * nilfs_error() sets an ERROR_FS flag on the superblock as well as
 101  * reporting an error message.  It should be called when NILFS detects
 102  * incoherences or defects of meta data on disk.  As for sustainable
 103  * errors such as a single-shot I/O error, nilfs_warning() or the printk()
 104  * function should be used instead.
 105  *
 106  * The segment constructor must not call this function because it can
 107  * kill itself.
 108  */
 109 void nilfs_error(struct super_block *sb, const char *function,
 110                  const char *fmt, ...)
 111 {
 112         struct the_nilfs *nilfs = sb->s_fs_info;
 113         struct va_format vaf;
 114         va_list args;
 115
 116         va_start(args, fmt);
 117
 118         vaf.fmt = fmt;
 119         vaf.va = &args;
 120
 121         printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
 122                sb->s_id, function, &vaf);
 123
 124         va_end(args);
 125
 126         if (!(sb->s_flags & MS_RDONLY)) {
 127                 nilfs_set_error(sb);
 128
 129                 if (nilfs_test_opt(nilfs, ERRORS_RO)) {
 130                         printk(KERN_CRIT "Remounting filesystem read-only\n");
 131                         sb->s_flags |= MS_RDONLY;
 132                 }
 133         }
 134
 135         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
 136                 panic("NILFS (device %s): panic forced after error\n",
 137                       sb->s_id);
 138 }
 139
 140 void nilfs_warning(struct super_block *sb, const char *function,
 141                    const char *fmt, ...)
 142 {
 143         struct va_format vaf;
 144         va_list args;
 145
 146         va_start(args, fmt);
 147
 148         vaf.fmt = fmt;
 149         vaf.va = &args;
 150
 151         printk(KERN_WARNING "NILFS warning (device %s): %s: %pV\n",
 152                sb->s_id, function, &vaf);
 153
 154         va_end(args);
 155 }
 156
 157
 158 struct inode *nilfs_alloc_inode(struct super_block *sb)
 159 {
 160         struct nilfs_inode_info *ii;
 161
 162         ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
 163         if (!ii)
 164                 return NULL;
 165         ii->i_bh = NULL;
 166         ii->i_state = 0;
 167         ii->i_cno = 0;
 168         ii->vfs_inode.i_version = 1;
 169         nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode, sb->s_bdi);
 170         return &ii->vfs_inode;
 171 }
 172
 173 static void nilfs_i_callback(struct rcu_head *head)
 174 {
 175         struct inode *inode = container_of(head, struct inode, i_rcu);
 176         struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
 177
 178         if (mdi) {
 179                 kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
 180                 kfree(mdi);
 181         }
 182         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
 183 }
 184
 185 void nilfs_destroy_inode(struct inode *inode)
 186 {
 187         call_rcu(&inode->i_rcu, nilfs_i_callback);
 188 }
 189
 190 static int nilfs_sync_super(struct super_block *sb, int flag)
 191 {
 192         struct the_nilfs *nilfs = sb->s_fs_info;
 193         int err;
 194
 195  retry:
 196         set_buffer_dirty(nilfs->ns_sbh[0]);
 197         if (nilfs_test_opt(nilfs, BARRIER)) {
 198                 err = __sync_dirty_buffer(nilfs->ns_sbh[0],
 199                                           WRITE_SYNC | WRITE_FLUSH_FUA);
 200         } else {
 201                 err = sync_dirty_buffer(nilfs->ns_sbh[0]);
 202         }
 203
 204         if (unlikely(err)) {
 205                 printk(KERN_ERR
 206                        "NILFS: unable to write superblock (err=%d)\n", err);
 207                 if (err == -EIO && nilfs->ns_sbh[1]) {
 208                         /*
 209                          * sbp[0] points to newer log than sbp[1],
 210                          * so copy sbp[0] to sbp[1] to take over sbp[0].
 211                          */
 212                         memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
 213                                nilfs->ns_sbsize);
 214                         nilfs_fall_back_super_block(nilfs);
 215                         goto retry;
 216                 }
 217         } else {
 218                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
 219
 220                 nilfs->ns_sbwcount++;
 221
 222                 /*
 223                  * The latest segment becomes trailable from the position
 224                  * written in superblock.
 225                  */
 226                 clear_nilfs_discontinued(nilfs);
 227
 228                 /* update GC protection for recent segments */
 229                 if (nilfs->ns_sbh[1]) {
 230                         if (flag == NILFS_SB_COMMIT_ALL) {
 231                                 set_buffer_dirty(nilfs->ns_sbh[1]);
 232                                 if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
 233                                         goto out;
 234                         }
 235                         if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
 236                             le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
 237                                 sbp = nilfs->ns_sbp[1];
 238                 }
 239
 240                 spin_lock(&nilfs->ns_last_segment_lock);
 241                 nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
 242                 spin_unlock(&nilfs->ns_last_segment_lock);
 243         }
 244  out:
 245         return err;
 246 }
 247
 248 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
 249                           struct the_nilfs *nilfs)
 250 {
 251         sector_t nfreeblocks;
 252
 253         /* nilfs->ns_sem must be locked by the caller. */
 254         nilfs_count_free_blocks(nilfs, &nfreeblocks);
 255         sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
 256
 257         spin_lock(&nilfs->ns_last_segment_lock);
 258         sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
 259         sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
 260         sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
 261         spin_unlock(&nilfs->ns_last_segment_lock);
 262 }
 263
 264 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
 265                                                int flip)
 266 {
 267         struct the_nilfs *nilfs = sb->s_fs_info;
 268         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 269
 270         /* nilfs->ns_sem must be locked by the caller. */
 271         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
 272                 if (sbp[1] &&
 273                     sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
 274                         memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
 275                 } else {
 276                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
 277                                sb->s_id);
 278                         return NULL;
 279                 }
 280         } else if (sbp[1] &&
 281                    sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
 282                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
 283         }
 284
 285         if (flip && sbp[1])
 286                 nilfs_swap_super_block(nilfs);
 287
 288         return sbp;
 289 }
 290
 291 int nilfs_commit_super(struct super_block *sb, int flag)
 292 {
 293         struct the_nilfs *nilfs = sb->s_fs_info;
 294         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 295         time_t t;
 296
 297         /* nilfs->ns_sem must be locked by the caller. */
 298         t = get_seconds();
 299         nilfs->ns_sbwtime = t;
 300         sbp[0]->s_wtime = cpu_to_le64(t);
 301         sbp[0]->s_sum = 0;
 302         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
 303                                              (unsigned char *)sbp[0],
 304                                              nilfs->ns_sbsize));
 305         if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
 306                 sbp[1]->s_wtime = sbp[0]->s_wtime;
 307                 sbp[1]->s_sum = 0;
 308                 sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
 309                                             (unsigned char *)sbp[1],
 310                                             nilfs->ns_sbsize));
 311         }
 312         clear_nilfs_sb_dirty(nilfs);
 313         nilfs->ns_flushed_device = 1;
 314         /* make sure store to ns_flushed_device cannot be reordered */
 315         smp_wmb();
 316         return nilfs_sync_super(sb, flag);
 317 }
 318
 319 /**
 320  * nilfs_cleanup_super() - write filesystem state for cleanup
 321  * @sb: super block instance to be unmounted or degraded to read-only
 322  *
 323  * This function restores state flags in the on-disk super block.
 324  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
 325  * filesystem was not clean previously.
 326  */
 327 int nilfs_cleanup_super(struct super_block *sb)
 328 {
 329         struct the_nilfs *nilfs = sb->s_fs_info;
 330         struct nilfs_super_block **sbp;
 331         int flag = NILFS_SB_COMMIT;
 332         int ret = -EIO;
 333
 334         sbp = nilfs_prepare_super(sb, 0);
 335         if (sbp) {
 336                 sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
 337                 nilfs_set_log_cursor(sbp[0], nilfs);
 338                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
 339                         /*
 340                          * make the "clean" flag also to the opposite
 341                          * super block if both super blocks point to
 342                          * the same checkpoint.
 343                          */
 344                         sbp[1]->s_state = sbp[0]->s_state;
 345                         flag = NILFS_SB_COMMIT_ALL;
 346                 }
 347                 ret = nilfs_commit_super(sb, flag);
 348         }
 349         return ret;
 350 }
 351
 352 /**
 353  * nilfs_move_2nd_super - relocate secondary super block
 354  * @sb: super block instance
 355  * @sb2off: new offset of the secondary super block (in bytes)
 356  */
 357 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
 358 {
 359         struct the_nilfs *nilfs = sb->s_fs_info;
 360         struct buffer_head *nsbh;
 361         struct nilfs_super_block *nsbp;
 362         sector_t blocknr, newblocknr;
 363         unsigned long offset;
 364         int sb2i = -1;  /* array index of the secondary superblock */
 365         int ret = 0;
 366
 367         /* nilfs->ns_sem must be locked by the caller. */
 368         if (nilfs->ns_sbh[1] &&
 369             nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
 370                 sb2i = 1;
 371                 blocknr = nilfs->ns_sbh[1]->b_blocknr;
 372         } else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
 373                 sb2i = 0;
 374                 blocknr = nilfs->ns_sbh[0]->b_blocknr;
 375         }
 376         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
 377                 goto out;  /* super block location is unchanged */
 378
 379         /* Get new super block buffer */
 380         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
 381         offset = sb2off & (nilfs->ns_blocksize - 1);
 382         nsbh = sb_getblk(sb, newblocknr);
 383         if (!nsbh) {
 384                 printk(KERN_WARNING
 385                        "NILFS warning: unable to move secondary superblock "
 386                        "to block %llu\n", (unsigned long long)newblocknr);
 387                 ret = -EIO;
 388                 goto out;
 389         }
 390         nsbp = (void *)nsbh->b_data + offset;
 391         memset(nsbp, 0, nilfs->ns_blocksize);
 392
 393         if (sb2i >= 0) {
 394                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
 395                 brelse(nilfs->ns_sbh[sb2i]);
 396                 nilfs->ns_sbh[sb2i] = nsbh;
 397                 nilfs->ns_sbp[sb2i] = nsbp;
 398         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
 399                 /* secondary super block will be restored to index 1 */
 400                 nilfs->ns_sbh[1] = nsbh;
 401                 nilfs->ns_sbp[1] = nsbp;
 402         } else {
 403                 brelse(nsbh);
 404         }
 405 out:
 406         return ret;
 407 }
 408
 409 /**
 410  * nilfs_resize_fs - resize the filesystem
 411  * @sb: super block instance
 412  * @newsize: new size of the filesystem (in bytes)
 413  */
 414 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
 415 {
 416         struct the_nilfs *nilfs = sb->s_fs_info;
 417         struct nilfs_super_block **sbp;
 418         __u64 devsize, newnsegs;
 419         loff_t sb2off;
 420         int ret;
 421
 422         ret = -ERANGE;
 423         devsize = i_size_read(sb->s_bdev->bd_inode);
 424         if (newsize > devsize)
 425                 goto out;
 426
 427         /*
 428          * Write lock is required to protect some functions depending
 429          * on the number of segments, the number of reserved segments,
 430          * and so forth.
 431          */
 432         down_write(&nilfs->ns_segctor_sem);
 433
 434         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
 435         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
 436         do_div(newnsegs, nilfs->ns_blocks_per_segment);
 437
 438         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
 439         up_write(&nilfs->ns_segctor_sem);
 440         if (ret < 0)
 441                 goto out;
 442
 443         ret = nilfs_construct_segment(sb);
 444         if (ret < 0)
 445                 goto out;
 446
 447         down_write(&nilfs->ns_sem);
 448         nilfs_move_2nd_super(sb, sb2off);
 449         ret = -EIO;
 450         sbp = nilfs_prepare_super(sb, 0);
 451         if (likely(sbp)) {
 452                 nilfs_set_log_cursor(sbp[0], nilfs);
 453                 /*
 454                  * Drop NILFS_RESIZE_FS flag for compatibility with
 455                  * mount-time resize which may be implemented in a
 456                  * future release.
 457                  */
 458                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
 459                                               ~NILFS_RESIZE_FS);
 460                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
 461                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
 462                 if (sbp[1])
 463                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
 464                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
 465         }
 466         up_write(&nilfs->ns_sem);
 467
 468         /*
 469          * Reset the range of allocatable segments last.  This order
 470          * is important in the case of expansion because the secondary
 471          * superblock must be protected from log write until migration
 472          * completes.
 473          */
 474         if (!ret)
 475                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
 476 out:
 477         return ret;
 478 }
 479
 480 static void nilfs_put_super(struct super_block *sb)
 481 {
 482         struct the_nilfs *nilfs = sb->s_fs_info;
 483
 484         nilfs_detach_log_writer(sb);
 485
 486         if (!(sb->s_flags & MS_RDONLY)) {
 487                 down_write(&nilfs->ns_sem);
 488                 nilfs_cleanup_super(sb);
 489                 up_write(&nilfs->ns_sem);
 490         }
 491
 492         iput(nilfs->ns_sufile);
 493         iput(nilfs->ns_cpfile);
 494         iput(nilfs->ns_dat);
 495
 496         destroy_nilfs(nilfs);
 497         sb->s_fs_info = NULL;
 498 }
 499
 500 static int nilfs_sync_fs(struct super_block *sb, int wait)
 501 {
 502         struct the_nilfs *nilfs = sb->s_fs_info;
 503         struct nilfs_super_block **sbp;
 504         int err = 0;
 505
 506         /* This function is called when super block should be written back */
 507         if (wait)
 508                 err = nilfs_construct_segment(sb);
 509
 510         down_write(&nilfs->ns_sem);
 511         if (nilfs_sb_dirty(nilfs)) {
 512                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
 513                 if (likely(sbp)) {
 514                         nilfs_set_log_cursor(sbp[0], nilfs);
 515                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
 516                 }
 517         }
 518         up_write(&nilfs->ns_sem);
 519
 520         if (!err)
 521                 err = nilfs_flush_device(nilfs);
 522
 523         return err;
 524 }
 525
 526 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
 527                             struct nilfs_root **rootp)
 528 {
 529         struct the_nilfs *nilfs = sb->s_fs_info;
 530         struct nilfs_root *root;
 531         struct nilfs_checkpoint *raw_cp;
 532         struct buffer_head *bh_cp;
 533         int err = -ENOMEM;
 534
 535         root = nilfs_find_or_create_root(
 536                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
 537         if (!root)
 538                 return err;
 539
 540         if (root->ifile)
 541                 goto reuse; /* already attached checkpoint */
 542
 543         down_read(&nilfs->ns_segctor_sem);
 544         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
 545                                           &bh_cp);
 546         up_read(&nilfs->ns_segctor_sem);
 547         if (unlikely(err)) {
 548                 if (err == -ENOENT || err == -EINVAL) {
 549                         printk(KERN_ERR
 550                                "NILFS: Invalid checkpoint "
 551                                "(checkpoint number=%llu)\n",
 552                                (unsigned long long)cno);
 553                         err = -EINVAL;
 554                 }
 555                 goto failed;
 556         }
 557
 558         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
 559                                &raw_cp->cp_ifile_inode, &root->ifile);
 560         if (err)
 561                 goto failed_bh;
 562
 563         atomic64_set(&root->inodes_count,
 564                         le64_to_cpu(raw_cp->cp_inodes_count));
 565         atomic64_set(&root->blocks_count,
 566                         le64_to_cpu(raw_cp->cp_blocks_count));
 567
 568         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
 569
 570  reuse:
 571         *rootp = root;
 572         return 0;
 573
 574  failed_bh:
 575         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
 576  failed:
 577         nilfs_put_root(root);
 578
 579         return err;
 580 }
 581
 582 static int nilfs_freeze(struct super_block *sb)
 583 {
 584         struct the_nilfs *nilfs = sb->s_fs_info;
 585         int err;
 586
 587         if (sb->s_flags & MS_RDONLY)
 588                 return 0;
 589
 590         /* Mark super block clean */
 591         down_write(&nilfs->ns_sem);
 592         err = nilfs_cleanup_super(sb);
 593         up_write(&nilfs->ns_sem);
 594         return err;
 595 }
 596
 597 static int nilfs_unfreeze(struct super_block *sb)
 598 {
 599         struct the_nilfs *nilfs = sb->s_fs_info;
 600
 601         if (sb->s_flags & MS_RDONLY)
 602                 return 0;
 603
 604         down_write(&nilfs->ns_sem);
 605         nilfs_setup_super(sb, false);
 606         up_write(&nilfs->ns_sem);
 607         return 0;
 608 }
 609
 610 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 611 {
 612         struct super_block *sb = dentry->d_sb;
 613         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
 614         struct the_nilfs *nilfs = root->nilfs;
 615         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 616         unsigned long long blocks;
 617         unsigned long overhead;
 618         unsigned long nrsvblocks;
 619         sector_t nfreeblocks;
 620         u64 nmaxinodes, nfreeinodes;
 621         int err;
 622
 623         /*
 624          * Compute all of the segment blocks
 625          *
 626          * The blocks before first segment and after last segment
 627          * are excluded.
 628          */
 629         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
 630                 - nilfs->ns_first_data_block;
 631         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
 632
 633         /*
 634          * Compute the overhead
 635          *
 636          * When distributing meta data blocks outside segment structure,
 637          * We must count them as the overhead.
 638          */
 639         overhead = 0;
 640
 641         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
 642         if (unlikely(err))
 643                 return err;
 644
 645         err = nilfs_ifile_count_free_inodes(root->ifile,
 646                                             &nmaxinodes, &nfreeinodes);
 647         if (unlikely(err)) {
 648                 printk(KERN_WARNING
 649                         "NILFS warning: fail to count free inodes: err %d.\n",
 650                         err);
 651                 if (err == -ERANGE) {
 652                         /*
 653                          * If nilfs_palloc_count_max_entries() returns
 654                          * -ERANGE error code then we simply treat
 655                          * curent inodes count as maximum possible and
 656                          * zero as free inodes value.
 657                          */
 658                         nmaxinodes = atomic64_read(&root->inodes_count);
 659                         nfreeinodes = 0;
 660                         err = 0;
 661                 } else
 662                         return err;
 663         }
 664
 665         buf->f_type = NILFS_SUPER_MAGIC;
 666         buf->f_bsize = sb->s_blocksize;
 667         buf->f_blocks = blocks - overhead;
 668         buf->f_bfree = nfreeblocks;
 669         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
 670                 (buf->f_bfree - nrsvblocks) : 0;
 671         buf->f_files = nmaxinodes;
 672         buf->f_ffree = nfreeinodes;
 673         buf->f_namelen = NILFS_NAME_LEN;
 674         buf->f_fsid.val[0] = (u32)id;
 675         buf->f_fsid.val[1] = (u32)(id >> 32);
 676
 677         return 0;
 678 }
 679
 680 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
 681 {
 682         struct super_block *sb = dentry->d_sb;
 683         struct the_nilfs *nilfs = sb->s_fs_info;
 684         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
 685
 686         if (!nilfs_test_opt(nilfs, BARRIER))
 687                 seq_puts(seq, ",nobarrier");
 688         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
 689                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
 690         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
 691                 seq_puts(seq, ",errors=panic");
 692         if (nilfs_test_opt(nilfs, ERRORS_CONT))
 693                 seq_puts(seq, ",errors=continue");
 694         if (nilfs_test_opt(nilfs, STRICT_ORDER))
 695                 seq_puts(seq, ",order=strict");
 696         if (nilfs_test_opt(nilfs, NORECOVERY))
 697                 seq_puts(seq, ",norecovery");
 698         if (nilfs_test_opt(nilfs, DISCARD))
 699                 seq_puts(seq, ",discard");
 700
 701         return 0;
 702 }
 703
 704 static const struct super_operations nilfs_sops = {
 705         .alloc_inode    = nilfs_alloc_inode,
 706         .destroy_inode  = nilfs_destroy_inode,
 707         .dirty_inode    = nilfs_dirty_inode,
 708         .evict_inode    = nilfs_evict_inode,
 709         .put_super      = nilfs_put_super,
 710         .sync_fs        = nilfs_sync_fs,
 711         .freeze_fs      = nilfs_freeze,
 712         .unfreeze_fs    = nilfs_unfreeze,
 713         .statfs         = nilfs_statfs,
 714         .remount_fs     = nilfs_remount,
 715         .show_options = nilfs_show_options
 716 };
 717
 718 enum {
 719         Opt_err_cont, Opt_err_panic, Opt_err_ro,
 720         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
 721         Opt_discard, Opt_nodiscard, Opt_err,
 722 };
 723
 724 static match_table_t tokens = {
 725         {Opt_err_cont, "errors=continue"},
 726         {Opt_err_panic, "errors=panic"},
 727         {Opt_err_ro, "errors=remount-ro"},
 728         {Opt_barrier, "barrier"},
 729         {Opt_nobarrier, "nobarrier"},
 730         {Opt_snapshot, "cp=%u"},
 731         {Opt_order, "order=%s"},
 732         {Opt_norecovery, "norecovery"},
 733         {Opt_discard, "discard"},
 734         {Opt_nodiscard, "nodiscard"},
 735         {Opt_err, NULL}
 736 };
 737
 738 static int parse_options(char *options, struct super_block *sb, int is_remount)
 739 {
 740         struct the_nilfs *nilfs = sb->s_fs_info;
 741         char *p;
 742         substring_t args[MAX_OPT_ARGS];
 743
 744         if (!options)
 745                 return 1;
 746
 747         while ((p = strsep(&options, ",")) != NULL) {
 748                 int token;
 749                 if (!*p)
 750                         continue;
 751
 752                 token = match_token(p, tokens, args);
 753                 switch (token) {
 754                 case Opt_barrier:
 755                         nilfs_set_opt(nilfs, BARRIER);
 756                         break;
 757                 case Opt_nobarrier:
 758                         nilfs_clear_opt(nilfs, BARRIER);
 759                         break;
 760                 case Opt_order:
 761                         if (strcmp(args[0].from, "relaxed") == 0)
 762                                 /* Ordered data semantics */
 763                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
 764                         else if (strcmp(args[0].from, "strict") == 0)
 765                                 /* Strict in-order semantics */
 766                                 nilfs_set_opt(nilfs, STRICT_ORDER);
 767                         else
 768                                 return 0;
 769                         break;
 770                 case Opt_err_panic:
 771                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
 772                         break;
 773                 case Opt_err_ro:
 774                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
 775                         break;
 776                 case Opt_err_cont:
 777                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
 778                         break;
 779                 case Opt_snapshot:
 780                         if (is_remount) {
 781                                 printk(KERN_ERR
 782                                        "NILFS: \"%s\" option is invalid "
 783                                        "for remount.\n", p);
 784                                 return 0;
 785                         }
 786                         break;
 787                 case Opt_norecovery:
 788                         nilfs_set_opt(nilfs, NORECOVERY);
 789                         break;
 790                 case Opt_discard:
 791                         nilfs_set_opt(nilfs, DISCARD);
 792                         break;
 793                 case Opt_nodiscard:
 794                         nilfs_clear_opt(nilfs, DISCARD);
 795                         break;
 796                 default:
 797                         printk(KERN_ERR
 798                                "NILFS: Unrecognized mount option \"%s\"\n", p);
 799                         return 0;
 800                 }
 801         }
 802         return 1;
 803 }
 804
 805 static inline void
 806 nilfs_set_default_options(struct super_block *sb,
 807                           struct nilfs_super_block *sbp)
 808 {
 809         struct the_nilfs *nilfs = sb->s_fs_info;
 810
 811         nilfs->ns_mount_opt =
 812                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
 813 }
 814
 815 static int nilfs_setup_super(struct super_block *sb, int is_mount)
 816 {
 817         struct the_nilfs *nilfs = sb->s_fs_info;
 818         struct nilfs_super_block **sbp;
 819         int max_mnt_count;
 820         int mnt_count;
 821
 822         /* nilfs->ns_sem must be locked by the caller. */
 823         sbp = nilfs_prepare_super(sb, 0);
 824         if (!sbp)
 825                 return -EIO;
 826
 827         if (!is_mount)
 828                 goto skip_mount_setup;
 829
 830         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
 831         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
 832
 833         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
 834                 printk(KERN_WARNING
 835                        "NILFS warning: mounting fs with errors\n");
 836 #if 0
 837         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
 838                 printk(KERN_WARNING
 839                        "NILFS warning: maximal mount count reached\n");
 840 #endif
 841         }
 842         if (!max_mnt_count)
 843                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
 844
 845         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
 846         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
 847
 848 skip_mount_setup:
 849         sbp[0]->s_state =
 850                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
 851         /* synchronize sbp[1] with sbp[0] */
 852         if (sbp[1])
 853                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
 854         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
 855 }
 856
 857 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
 858                                                  u64 pos, int blocksize,
 859                                                  struct buffer_head **pbh)
 860 {
 861         unsigned long long sb_index = pos;
 862         unsigned long offset;
 863
 864         offset = do_div(sb_index, blocksize);
 865         *pbh = sb_bread(sb, sb_index);
 866         if (!*pbh)
 867                 return NULL;
 868         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
 869 }
 870
 871 int nilfs_store_magic_and_option(struct super_block *sb,
 872                                  struct nilfs_super_block *sbp,
 873                                  char *data)
 874 {
 875         struct the_nilfs *nilfs = sb->s_fs_info;
 876
 877         sb->s_magic = le16_to_cpu(sbp->s_magic);
 878
 879         /* FS independent flags */
 880 #ifdef NILFS_ATIME_DISABLE
 881         sb->s_flags |= MS_NOATIME;
 882 #endif
 883
 884         nilfs_set_default_options(sb, sbp);
 885
 886         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
 887         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
 888         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
 889         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
 890
 891         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
 892 }
 893
 894 int nilfs_check_feature_compatibility(struct super_block *sb,
 895                                       struct nilfs_super_block *sbp)
 896 {
 897         __u64 features;
 898
 899         features = le64_to_cpu(sbp->s_feature_incompat) &
 900                 ~NILFS_FEATURE_INCOMPAT_SUPP;
 901         if (features) {
 902                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
 903                        "optional features (%llx)\n",
 904                        (unsigned long long)features);
 905                 return -EINVAL;
 906         }
 907         features = le64_to_cpu(sbp->s_feature_compat_ro) &
 908                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
 909         if (!(sb->s_flags & MS_RDONLY) && features) {
 910                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
 911                        "unsupported optional features (%llx)\n",
 912                        (unsigned long long)features);
 913                 return -EINVAL;
 914         }
 915         return 0;
 916 }
 917
 918 static int nilfs_get_root_dentry(struct super_block *sb,
 919                                  struct nilfs_root *root,
 920                                  struct dentry **root_dentry)
 921 {
 922         struct inode *inode;
 923         struct dentry *dentry;
 924         int ret = 0;
 925
 926         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
 927         if (IS_ERR(inode)) {
 928                 printk(KERN_ERR "NILFS: get root inode failed\n");
 929                 ret = PTR_ERR(inode);
 930                 goto out;
 931         }
 932         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
 933                 iput(inode);
 934                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
 935                 ret = -EINVAL;
 936                 goto out;
 937         }
 938
 939         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
 940                 dentry = d_find_alias(inode);
 941                 if (!dentry) {
 942                         dentry = d_make_root(inode);
 943                         if (!dentry) {
 944                                 ret = -ENOMEM;
 945                                 goto failed_dentry;
 946                         }
 947                 } else {
 948                         iput(inode);
 949                 }
 950         } else {
 951                 dentry = d_obtain_root(inode);
 952                 if (IS_ERR(dentry)) {
 953                         ret = PTR_ERR(dentry);
 954                         goto failed_dentry;
 955                 }
 956         }
 957         *root_dentry = dentry;
 958  out:
 959         return ret;
 960
 961  failed_dentry:
 962         printk(KERN_ERR "NILFS: get root dentry failed\n");
 963         goto out;
 964 }
 965
 966 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
 967                                  struct dentry **root_dentry)
 968 {
 969         struct the_nilfs *nilfs = s->s_fs_info;
 970         struct nilfs_root *root;
 971         int ret;
 972
 973         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
 974
 975         down_read(&nilfs->ns_segctor_sem);
 976         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
 977         up_read(&nilfs->ns_segctor_sem);
 978         if (ret < 0) {
 979                 ret = (ret == -ENOENT) ? -EINVAL : ret;
 980                 goto out;
 981         } else if (!ret) {
 982                 printk(KERN_ERR "NILFS: The specified checkpoint is "
 983                        "not a snapshot (checkpoint number=%llu).\n",
 984                        (unsigned long long)cno);
 985                 ret = -EINVAL;
 986                 goto out;
 987         }
 988
 989         ret = nilfs_attach_checkpoint(s, cno, false, &root);
 990         if (ret) {
 991                 printk(KERN_ERR "NILFS: error loading snapshot "
 992                        "(checkpoint number=%llu).\n",
 993                (unsigned long long)cno);
 994                 goto out;
 995         }
 996         ret = nilfs_get_root_dentry(s, root, root_dentry);
 997         nilfs_put_root(root);
 998  out:
 999         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
1000         return ret;
1001 }
1002
1003 /**
1004  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
1005  * @root_dentry: root dentry of the tree to be shrunk
1006  *
1007  * This function returns true if the tree was in-use.
1008  */
1009 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1010 {
1011         shrink_dcache_parent(root_dentry);
1012         return d_count(root_dentry) > 1;
1013 }
1014
1015 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1016 {
1017         struct the_nilfs *nilfs = sb->s_fs_info;
1018         struct nilfs_root *root;
1019         struct inode *inode;
1020         struct dentry *dentry;
1021         int ret;
1022
1023         if (cno < 0 || cno > nilfs->ns_cno)
1024                 return false;
1025
1026         if (cno >= nilfs_last_cno(nilfs))
1027                 return true;    /* protect recent checkpoints */
1028
1029         ret = false;
1030         root = nilfs_lookup_root(nilfs, cno);
1031         if (root) {
1032                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1033                 if (inode) {
1034                         dentry = d_find_alias(inode);
1035                         if (dentry) {
1036                                 ret = nilfs_tree_is_busy(dentry);
1037                                 dput(dentry);
1038                         }
1039                         iput(inode);
1040                 }
1041                 nilfs_put_root(root);
1042         }
1043         return ret;
1044 }
1045
1046 /**
1047  * nilfs_fill_super() - initialize a super block instance
1048  * @sb: super_block
1049  * @data: mount options
1050  * @silent: silent mode flag
1051  *
1052  * This function is called exclusively by nilfs->ns_mount_mutex.
1053  * So, the recovery process is protected from other simultaneous mounts.
1054  */
1055 static int
1056 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1057 {
1058         struct the_nilfs *nilfs;
1059         struct nilfs_root *fsroot;
1060         struct backing_dev_info *bdi;
1061         __u64 cno;
1062         int err;
1063
1064         nilfs = alloc_nilfs(sb->s_bdev);
1065         if (!nilfs)
1066                 return -ENOMEM;
1067
1068         sb->s_fs_info = nilfs;
1069
1070         err = init_nilfs(nilfs, sb, (char *)data);
1071         if (err)
1072                 goto failed_nilfs;
1073
1074         sb->s_op = &nilfs_sops;
1075         sb->s_export_op = &nilfs_export_ops;
1076         sb->s_root = NULL;
1077         sb->s_time_gran = 1;
1078         sb->s_max_links = NILFS_LINK_MAX;
1079
1080         bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
1081         sb->s_bdi = bdi ? : &default_backing_dev_info;
1082
1083         err = load_nilfs(nilfs, sb);
1084         if (err)
1085                 goto failed_nilfs;
1086
1087         cno = nilfs_last_cno(nilfs);
1088         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1089         if (err) {
1090                 printk(KERN_ERR "NILFS: error loading last checkpoint "
1091                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
1092                 goto failed_unload;
1093         }
1094
1095         if (!(sb->s_flags & MS_RDONLY)) {
1096                 err = nilfs_attach_log_writer(sb, fsroot);
1097                 if (err)
1098                         goto failed_checkpoint;
1099         }
1100
1101         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1102         if (err)
1103                 goto failed_segctor;
1104
1105         nilfs_put_root(fsroot);
1106
1107         if (!(sb->s_flags & MS_RDONLY)) {
1108                 down_write(&nilfs->ns_sem);
1109                 nilfs_setup_super(sb, true);
1110                 up_write(&nilfs->ns_sem);
1111         }
1112
1113         return 0;
1114
1115  failed_segctor:
1116         nilfs_detach_log_writer(sb);
1117
1118  failed_checkpoint:
1119         nilfs_put_root(fsroot);
1120
1121  failed_unload:
1122         iput(nilfs->ns_sufile);
1123         iput(nilfs->ns_cpfile);
1124         iput(nilfs->ns_dat);
1125
1126  failed_nilfs:
1127         destroy_nilfs(nilfs);
1128         return err;
1129 }
1130
1131 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1132 {
1133         struct the_nilfs *nilfs = sb->s_fs_info;
1134         unsigned long old_sb_flags;
1135         unsigned long old_mount_opt;
1136         int err;
1137
1138         sync_filesystem(sb);
1139         old_sb_flags = sb->s_flags;
1140         old_mount_opt = nilfs->ns_mount_opt;
1141
1142         if (!parse_options(data, sb, 1)) {
1143                 err = -EINVAL;
1144                 goto restore_opts;
1145         }
1146         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1147
1148         err = -EINVAL;
1149
1150         if (!nilfs_valid_fs(nilfs)) {
1151                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1152                        "remount because the filesystem is in an "
1153                        "incomplete recovery state.\n", sb->s_id);
1154                 goto restore_opts;
1155         }
1156
1157         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1158                 goto out;
1159         if (*flags & MS_RDONLY) {
1160                 /* Shutting down log writer */
1161                 nilfs_detach_log_writer(sb);
1162                 sb->s_flags |= MS_RDONLY;
1163
1164                 /*
1165                  * Remounting a valid RW partition RDONLY, so set
1166                  * the RDONLY flag and then mark the partition as valid again.
1167                  */
1168                 down_write(&nilfs->ns_sem);
1169                 nilfs_cleanup_super(sb);
1170                 up_write(&nilfs->ns_sem);
1171         } else {
1172                 __u64 features;
1173                 struct nilfs_root *root;
1174
1175                 /*
1176                  * Mounting a RDONLY partition read-write, so reread and
1177                  * store the current valid flag.  (It may have been changed
1178                  * by fsck since we originally mounted the partition.)
1179                  */
1180                 down_read(&nilfs->ns_sem);
1181                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1182                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1183                 up_read(&nilfs->ns_sem);
1184                 if (features) {
1185                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1186                                "remount RDWR because of unsupported optional "
1187                                "features (%llx)\n",
1188                                sb->s_id, (unsigned long long)features);
1189                         err = -EROFS;
1190                         goto restore_opts;
1191                 }
1192
1193                 sb->s_flags &= ~MS_RDONLY;
1194
1195                 root = NILFS_I(sb->s_root->d_inode)->i_root;
1196                 err = nilfs_attach_log_writer(sb, root);
1197                 if (err)
1198                         goto restore_opts;
1199
1200                 down_write(&nilfs->ns_sem);
1201                 nilfs_setup_super(sb, true);
1202                 up_write(&nilfs->ns_sem);
1203         }
1204  out:
1205         return 0;
1206
1207  restore_opts:
1208         sb->s_flags = old_sb_flags;
1209         nilfs->ns_mount_opt = old_mount_opt;
1210         return err;
1211 }
1212
1213 struct nilfs_super_data {
1214         struct block_device *bdev;
1215         __u64 cno;
1216         int flags;
1217 };
1218
1219 /**
1220  * nilfs_identify - pre-read mount options needed to identify mount instance
1221  * @data: mount options
1222  * @sd: nilfs_super_data
1223  */
1224 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1225 {
1226         char *p, *options = data;
1227         substring_t args[MAX_OPT_ARGS];
1228         int token;
1229         int ret = 0;
1230
1231         do {
1232                 p = strsep(&options, ",");
1233                 if (p != NULL && *p) {
1234                         token = match_token(p, tokens, args);
1235                         if (token == Opt_snapshot) {
1236                                 if (!(sd->flags & MS_RDONLY)) {
1237                                         ret++;
1238                                 } else {
1239                                         sd->cno = simple_strtoull(args[0].from,
1240                                                                   NULL, 0);
1241                                         /*
1242                                          * No need to see the end pointer;
1243                                          * match_token() has done syntax
1244                                          * checking.
1245                                          */
1246                                         if (sd->cno == 0)
1247                                                 ret++;
1248                                 }
1249                         }
1250                         if (ret)
1251                                 printk(KERN_ERR
1252                                        "NILFS: invalid mount option: %s\n", p);
1253                 }
1254                 if (!options)
1255                         break;
1256                 BUG_ON(options == data);
1257                 *(options - 1) = ',';
1258         } while (!ret);
1259         return ret;
1260 }
1261
1262 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1263 {
1264         s->s_bdev = data;
1265         s->s_dev = s->s_bdev->bd_dev;
1266         return 0;
1267 }
1268
1269 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1270 {
1271         return (void *)s->s_bdev == data;
1272 }
1273
1274 static struct dentry *
1275 nilfs_mount(struct file_system_type *fs_type, int flags,
1276              const char *dev_name, void *data)
1277 {
1278         struct nilfs_super_data sd;
1279         struct super_block *s;
1280         fmode_t mode = FMODE_READ | FMODE_EXCL;
1281         struct dentry *root_dentry;
1282         int err, s_new = false;
1283
1284         if (!(flags & MS_RDONLY))
1285                 mode |= FMODE_WRITE;
1286
1287         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1288         if (IS_ERR(sd.bdev))
1289                 return ERR_CAST(sd.bdev);
1290
1291         sd.cno = 0;
1292         sd.flags = flags;
1293         if (nilfs_identify((char *)data, &sd)) {
1294                 err = -EINVAL;
1295                 goto failed;
1296         }
1297
1298         /*
1299          * once the super is inserted into the list by sget, s_umount
1300          * will protect the lockfs code from trying to start a snapshot
1301          * while we are mounting
1302          */
1303         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1304         if (sd.bdev->bd_fsfreeze_count > 0) {
1305                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1306                 err = -EBUSY;
1307                 goto failed;
1308         }
1309         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1310                  sd.bdev);
1311         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1312         if (IS_ERR(s)) {
1313                 err = PTR_ERR(s);
1314                 goto failed;
1315         }
1316
1317         if (!s->s_root) {
1318                 char b[BDEVNAME_SIZE];
1319
1320                 s_new = true;
1321
1322                 /* New superblock instance created */
1323                 s->s_mode = mode;
1324                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1325                 sb_set_blocksize(s, block_size(sd.bdev));
1326
1327                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1328                 if (err)
1329                         goto failed_super;
1330
1331                 s->s_flags |= MS_ACTIVE;
1332         } else if (!sd.cno) {
1333                 if (nilfs_tree_is_busy(s->s_root)) {
1334                         if ((flags ^ s->s_flags) & MS_RDONLY) {
1335                                 printk(KERN_ERR "NILFS: the device already "
1336                                        "has a %s mount.\n",
1337                                        (s->s_flags & MS_RDONLY) ?
1338                                        "read-only" : "read/write");
1339                                 err = -EBUSY;
1340                                 goto failed_super;
1341                         }
1342                 } else {
1343                         /*
1344                          * Try remount to setup mount states if the current
1345                          * tree is not mounted and only snapshots use this sb.
1346                          */
1347                         err = nilfs_remount(s, &flags, data);
1348                         if (err)
1349                                 goto failed_super;
1350                 }
1351         }
1352
1353         if (sd.cno) {
1354                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1355                 if (err)
1356                         goto failed_super;
1357         } else {
1358                 root_dentry = dget(s->s_root);
1359         }
1360
1361         if (!s_new)
1362                 blkdev_put(sd.bdev, mode);
1363
1364         return root_dentry;
1365
1366  failed_super:
1367         deactivate_locked_super(s);
1368
1369  failed:
1370         if (!s_new)
1371                 blkdev_put(sd.bdev, mode);
1372         return ERR_PTR(err);
1373 }
1374
1375 struct file_system_type nilfs_fs_type = {
1376         .owner    = THIS_MODULE,
1377         .name     = "nilfs2",
1378         .mount    = nilfs_mount,
1379         .kill_sb  = kill_block_super,
1380         .fs_flags = FS_REQUIRES_DEV,
1381 };
1382 MODULE_ALIAS_FS("nilfs2");
1383
1384 static void nilfs_inode_init_once(void *obj)
1385 {
1386         struct nilfs_inode_info *ii = obj;
1387
1388         INIT_LIST_HEAD(&ii->i_dirty);
1389 #ifdef CONFIG_NILFS_XATTR
1390         init_rwsem(&ii->xattr_sem);
1391 #endif
1392         address_space_init_once(&ii->i_btnode_cache);
1393         ii->i_bmap = &ii->i_bmap_data;
1394         inode_init_once(&ii->vfs_inode);
1395 }
1396
1397 static void nilfs_segbuf_init_once(void *obj)
1398 {
1399         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1400 }
1401
1402 static void nilfs_destroy_cachep(void)
1403 {
1404         /*
1405          * Make sure all delayed rcu free inodes are flushed before we
1406          * destroy cache.
1407          */
1408         rcu_barrier();
1409
1410         if (nilfs_inode_cachep)
1411                 kmem_cache_destroy(nilfs_inode_cachep);
1412         if (nilfs_transaction_cachep)
1413                 kmem_cache_destroy(nilfs_transaction_cachep);
1414         if (nilfs_segbuf_cachep)
1415                 kmem_cache_destroy(nilfs_segbuf_cachep);
1416         if (nilfs_btree_path_cache)
1417                 kmem_cache_destroy(nilfs_btree_path_cache);
1418 }
1419
1420 static int __init nilfs_init_cachep(void)
1421 {
1422         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1423                         sizeof(struct nilfs_inode_info), 0,
1424                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1425         if (!nilfs_inode_cachep)
1426                 goto fail;
1427
1428         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1429                         sizeof(struct nilfs_transaction_info), 0,
1430                         SLAB_RECLAIM_ACCOUNT, NULL);
1431         if (!nilfs_transaction_cachep)
1432                 goto fail;
1433
1434         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1435                         sizeof(struct nilfs_segment_buffer), 0,
1436                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1437         if (!nilfs_segbuf_cachep)
1438                 goto fail;
1439
1440         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1441                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1442                         0, 0, NULL);
1443         if (!nilfs_btree_path_cache)
1444                 goto fail;
1445
1446         return 0;
1447
1448 fail:
1449         nilfs_destroy_cachep();
1450         return -ENOMEM;
1451 }
1452
1453 static int __init init_nilfs_fs(void)
1454 {
1455         int err;
1456
1457         err = nilfs_init_cachep();
1458         if (err)
1459                 goto fail;
1460
1461         err = nilfs_sysfs_init();
1462         if (err)
1463                 goto free_cachep;
1464
1465         err = register_filesystem(&nilfs_fs_type);
1466         if (err)
1467                 goto deinit_sysfs_entry;
1468
1469         printk(KERN_INFO "NILFS version 2 loaded\n");
1470         return 0;
1471
1472 deinit_sysfs_entry:
1473         nilfs_sysfs_exit();
1474 free_cachep:
1475         nilfs_destroy_cachep();
1476 fail:
1477         return err;
1478 }
1479
1480 static void __exit exit_nilfs_fs(void)
1481 {
1482         nilfs_destroy_cachep();
1483         nilfs_sysfs_exit();
1484         unregister_filesystem(&nilfs_fs_type);
1485 }
1486
1487 module_init(init_nilfs_fs)
1488 module_exit(exit_nilfs_fs)