fs/ext2/super.c

   1 /*
   2  *  linux/fs/ext2/super.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/inode.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  Big-endian to little-endian byte-swapping/bitmaps by
  16  *        David S. Miller (davem@caip.rutgers.edu), 1995
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/string.h>
  21 #include <linux/fs.h>
  22 #include <linux/slab.h>
  23 #include <linux/init.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/parser.h>
  26 #include <linux/random.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/vfs.h>
  30 #include <linux/seq_file.h>
  31 #include <linux/mount.h>
  32 #include <asm/uaccess.h>
  33 #include "ext2.h"
  34 #include "xattr.h"
  35 #include "acl.h"
  36 #include "xip.h"
  37
  38 static void ext2_sync_super(struct super_block *sb,
  39                             struct ext2_super_block *es);
  40 static int ext2_remount (struct super_block * sb, int * flags, char * data);
  41 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
  42
  43 void ext2_error (struct super_block * sb, const char * function,
  44                  const char * fmt, ...)
  45 {
  46         va_list args;
  47         struct ext2_sb_info *sbi = EXT2_SB(sb);
  48         struct ext2_super_block *es = sbi->s_es;
  49
  50         if (!(sb->s_flags & MS_RDONLY)) {
  51                 sbi->s_mount_state |= EXT2_ERROR_FS;
  52                 es->s_state =
  53                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
  54                 ext2_sync_super(sb, es);
  55         }
  56
  57         va_start(args, fmt);
  58         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
  59         vprintk(fmt, args);
  60         printk("\n");
  61         va_end(args);
  62
  63         if (test_opt(sb, ERRORS_PANIC))
  64                 panic("EXT2-fs panic from previous error\n");
  65         if (test_opt(sb, ERRORS_RO)) {
  66                 printk("Remounting filesystem read-only\n");
  67                 sb->s_flags |= MS_RDONLY;
  68         }
  69 }
  70
  71 void ext2_warning (struct super_block * sb, const char * function,
  72                    const char * fmt, ...)
  73 {
  74         va_list args;
  75
  76         va_start(args, fmt);
  77         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
  78                sb->s_id, function);
  79         vprintk(fmt, args);
  80         printk("\n");
  81         va_end(args);
  82 }
  83
  84 void ext2_update_dynamic_rev(struct super_block *sb)
  85 {
  86         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
  87
  88         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
  89                 return;
  90
  91         ext2_warning(sb, __FUNCTION__,
  92                      "updating to rev %d because of new feature flag, "
  93                      "running e2fsck is recommended",
  94                      EXT2_DYNAMIC_REV);
  95
  96         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
  97         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
  98         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
  99         /* leave es->s_feature_*compat flags alone */
 100         /* es->s_uuid will be set by e2fsck if empty */
 101
 102         /*
 103          * The rest of the superblock fields should be zero, and if not it
 104          * means they are likely already in use, so leave them alone.  We
 105          * can leave it up to e2fsck to clean up any inconsistencies there.
 106          */
 107 }
 108
 109 static void ext2_put_super (struct super_block * sb)
 110 {
 111         int db_count;
 112         int i;
 113         struct ext2_sb_info *sbi = EXT2_SB(sb);
 114
 115         ext2_xattr_put_super(sb);
 116         if (!(sb->s_flags & MS_RDONLY)) {
 117                 struct ext2_super_block *es = sbi->s_es;
 118
 119                 es->s_state = cpu_to_le16(sbi->s_mount_state);
 120                 ext2_sync_super(sb, es);
 121         }
 122         db_count = sbi->s_gdb_count;
 123         for (i = 0; i < db_count; i++)
 124                 if (sbi->s_group_desc[i])
 125                         brelse (sbi->s_group_desc[i]);
 126         kfree(sbi->s_group_desc);
 127         kfree(sbi->s_debts);
 128         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 129         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 130         percpu_counter_destroy(&sbi->s_dirs_counter);
 131         brelse (sbi->s_sbh);
 132         sb->s_fs_info = NULL;
 133         kfree(sbi);
 134
 135         return;
 136 }
 137
 138 static struct kmem_cache * ext2_inode_cachep;
 139
 140 static struct inode *ext2_alloc_inode(struct super_block *sb)
 141 {
 142         struct ext2_inode_info *ei;
 143         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, GFP_KERNEL);
 144         if (!ei)
 145                 return NULL;
 146 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 147         ei->i_acl = EXT2_ACL_NOT_CACHED;
 148         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 149 #endif
 150         ei->vfs_inode.i_version = 1;
 151         return &ei->vfs_inode;
 152 }
 153
 154 static void ext2_destroy_inode(struct inode *inode)
 155 {
 156         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
 157 }
 158
 159 static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
 160 {
 161         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
 162
 163         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 164             SLAB_CTOR_CONSTRUCTOR) {
 165                 rwlock_init(&ei->i_meta_lock);
 166 #ifdef CONFIG_EXT2_FS_XATTR
 167                 init_rwsem(&ei->xattr_sem);
 168 #endif
 169                 inode_init_once(&ei->vfs_inode);
 170         }
 171 }
 172
 173 static int init_inodecache(void)
 174 {
 175         ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
 176                                              sizeof(struct ext2_inode_info),
 177                                              0, (SLAB_RECLAIM_ACCOUNT|
 178                                                 SLAB_MEM_SPREAD),
 179                                              init_once, NULL);
 180         if (ext2_inode_cachep == NULL)
 181                 return -ENOMEM;
 182         return 0;
 183 }
 184
 185 static void destroy_inodecache(void)
 186 {
 187         kmem_cache_destroy(ext2_inode_cachep);
 188 }
 189
 190 static void ext2_clear_inode(struct inode *inode)
 191 {
 192 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 193         struct ext2_inode_info *ei = EXT2_I(inode);
 194
 195         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
 196                 posix_acl_release(ei->i_acl);
 197                 ei->i_acl = EXT2_ACL_NOT_CACHED;
 198         }
 199         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
 200                 posix_acl_release(ei->i_default_acl);
 201                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 202         }
 203 #endif
 204 }
 205
 206 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
 207 {
 208         struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
 209
 210         if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
 211                 seq_puts(seq, ",grpid");
 212
 213 #if defined(CONFIG_QUOTA)
 214         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
 215                 seq_puts(seq, ",usrquota");
 216
 217         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
 218                 seq_puts(seq, ",grpquota");
 219 #endif
 220
 221 #if defined(CONFIG_EXT2_FS_XIP)
 222         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
 223                 seq_puts(seq, ",xip");
 224 #endif
 225
 226         return 0;
 227 }
 228
 229 #ifdef CONFIG_QUOTA
 230 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
 231 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
 232 #endif
 233
 234 static struct super_operations ext2_sops = {
 235         .alloc_inode    = ext2_alloc_inode,
 236         .destroy_inode  = ext2_destroy_inode,
 237         .read_inode     = ext2_read_inode,
 238         .write_inode    = ext2_write_inode,
 239         .put_inode      = ext2_put_inode,
 240         .delete_inode   = ext2_delete_inode,
 241         .put_super      = ext2_put_super,
 242         .write_super    = ext2_write_super,
 243         .statfs         = ext2_statfs,
 244         .remount_fs     = ext2_remount,
 245         .clear_inode    = ext2_clear_inode,
 246         .show_options   = ext2_show_options,
 247 #ifdef CONFIG_QUOTA
 248         .quota_read     = ext2_quota_read,
 249         .quota_write    = ext2_quota_write,
 250 #endif
 251 };
 252
 253 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
 254 {
 255         __u32 *objp = vobjp;
 256         unsigned long ino = objp[0];
 257         __u32 generation = objp[1];
 258         struct inode *inode;
 259         struct dentry *result;
 260
 261         if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
 262                 return ERR_PTR(-ESTALE);
 263         if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
 264                 return ERR_PTR(-ESTALE);
 265
 266         /* iget isn't really right if the inode is currently unallocated!!
 267          * ext2_read_inode currently does appropriate checks, but
 268          * it might be "neater" to call ext2_get_inode first and check
 269          * if the inode is valid.....
 270          */
 271         inode = iget(sb, ino);
 272         if (inode == NULL)
 273                 return ERR_PTR(-ENOMEM);
 274         if (is_bad_inode(inode) ||
 275             (generation && inode->i_generation != generation)) {
 276                 /* we didn't find the right inode.. */
 277                 iput(inode);
 278                 return ERR_PTR(-ESTALE);
 279         }
 280         /* now to find a dentry.
 281          * If possible, get a well-connected one
 282          */
 283         result = d_alloc_anon(inode);
 284         if (!result) {
 285                 iput(inode);
 286                 return ERR_PTR(-ENOMEM);
 287         }
 288         return result;
 289 }
 290
 291 /* Yes, most of these are left as NULL!!
 292  * A NULL value implies the default, which works with ext2-like file
 293  * systems, but can be improved upon.
 294  * Currently only get_parent is required.
 295  */
 296 static struct export_operations ext2_export_ops = {
 297         .get_parent = ext2_get_parent,
 298         .get_dentry = ext2_get_dentry,
 299 };
 300
 301 static unsigned long get_sb_block(void **data)
 302 {
 303         unsigned long   sb_block;
 304         char            *options = (char *) *data;
 305
 306         if (!options || strncmp(options, "sb=", 3) != 0)
 307                 return 1;       /* Default location */
 308         options += 3;
 309         sb_block = simple_strtoul(options, &options, 0);
 310         if (*options && *options != ',') {
 311                 printk("EXT2-fs: Invalid sb specification: %s\n",
 312                        (char *) *data);
 313                 return 1;
 314         }
 315         if (*options == ',')
 316                 options++;
 317         *data = (void *) options;
 318         return sb_block;
 319 }
 320
 321 enum {
 322         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 323         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
 324         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
 325         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
 326         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
 327         Opt_usrquota, Opt_grpquota
 328 };
 329
 330 static match_table_t tokens = {
 331         {Opt_bsd_df, "bsddf"},
 332         {Opt_minix_df, "minixdf"},
 333         {Opt_grpid, "grpid"},
 334         {Opt_grpid, "bsdgroups"},
 335         {Opt_nogrpid, "nogrpid"},
 336         {Opt_nogrpid, "sysvgroups"},
 337         {Opt_resgid, "resgid=%u"},
 338         {Opt_resuid, "resuid=%u"},
 339         {Opt_sb, "sb=%u"},
 340         {Opt_err_cont, "errors=continue"},
 341         {Opt_err_panic, "errors=panic"},
 342         {Opt_err_ro, "errors=remount-ro"},
 343         {Opt_nouid32, "nouid32"},
 344         {Opt_nocheck, "check=none"},
 345         {Opt_nocheck, "nocheck"},
 346         {Opt_debug, "debug"},
 347         {Opt_oldalloc, "oldalloc"},
 348         {Opt_orlov, "orlov"},
 349         {Opt_nobh, "nobh"},
 350         {Opt_user_xattr, "user_xattr"},
 351         {Opt_nouser_xattr, "nouser_xattr"},
 352         {Opt_acl, "acl"},
 353         {Opt_noacl, "noacl"},
 354         {Opt_xip, "xip"},
 355         {Opt_grpquota, "grpquota"},
 356         {Opt_ignore, "noquota"},
 357         {Opt_quota, "quota"},
 358         {Opt_usrquota, "usrquota"},
 359         {Opt_err, NULL}
 360 };
 361
 362 static int parse_options (char * options,
 363                           struct ext2_sb_info *sbi)
 364 {
 365         char * p;
 366         substring_t args[MAX_OPT_ARGS];
 367         int option;
 368
 369         if (!options)
 370                 return 1;
 371
 372         while ((p = strsep (&options, ",")) != NULL) {
 373                 int token;
 374                 if (!*p)
 375                         continue;
 376
 377                 token = match_token(p, tokens, args);
 378                 switch (token) {
 379                 case Opt_bsd_df:
 380                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 381                         break;
 382                 case Opt_minix_df:
 383                         set_opt (sbi->s_mount_opt, MINIX_DF);
 384                         break;
 385                 case Opt_grpid:
 386                         set_opt (sbi->s_mount_opt, GRPID);
 387                         break;
 388                 case Opt_nogrpid:
 389                         clear_opt (sbi->s_mount_opt, GRPID);
 390                         break;
 391                 case Opt_resuid:
 392                         if (match_int(&args[0], &option))
 393                                 return 0;
 394                         sbi->s_resuid = option;
 395                         break;
 396                 case Opt_resgid:
 397                         if (match_int(&args[0], &option))
 398                                 return 0;
 399                         sbi->s_resgid = option;
 400                         break;
 401                 case Opt_sb:
 402                         /* handled by get_sb_block() instead of here */
 403                         /* *sb_block = match_int(&args[0]); */
 404                         break;
 405                 case Opt_err_panic:
 406                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
 407                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
 408                         set_opt (sbi->s_mount_opt, ERRORS_PANIC);
 409                         break;
 410                 case Opt_err_ro:
 411                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
 412                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
 413                         set_opt (sbi->s_mount_opt, ERRORS_RO);
 414                         break;
 415                 case Opt_err_cont:
 416                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
 417                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
 418                         set_opt (sbi->s_mount_opt, ERRORS_CONT);
 419                         break;
 420                 case Opt_nouid32:
 421                         set_opt (sbi->s_mount_opt, NO_UID32);
 422                         break;
 423                 case Opt_nocheck:
 424                         clear_opt (sbi->s_mount_opt, CHECK);
 425                         break;
 426                 case Opt_debug:
 427                         set_opt (sbi->s_mount_opt, DEBUG);
 428                         break;
 429                 case Opt_oldalloc:
 430                         set_opt (sbi->s_mount_opt, OLDALLOC);
 431                         break;
 432                 case Opt_orlov:
 433                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 434                         break;
 435                 case Opt_nobh:
 436                         set_opt (sbi->s_mount_opt, NOBH);
 437                         break;
 438 #ifdef CONFIG_EXT2_FS_XATTR
 439                 case Opt_user_xattr:
 440                         set_opt (sbi->s_mount_opt, XATTR_USER);
 441                         break;
 442                 case Opt_nouser_xattr:
 443                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 444                         break;
 445 #else
 446                 case Opt_user_xattr:
 447                 case Opt_nouser_xattr:
 448                         printk("EXT2 (no)user_xattr options not supported\n");
 449                         break;
 450 #endif
 451 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 452                 case Opt_acl:
 453                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 454                         break;
 455                 case Opt_noacl:
 456                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 457                         break;
 458 #else
 459                 case Opt_acl:
 460                 case Opt_noacl:
 461                         printk("EXT2 (no)acl options not supported\n");
 462                         break;
 463 #endif
 464                 case Opt_xip:
 465 #ifdef CONFIG_EXT2_FS_XIP
 466                         set_opt (sbi->s_mount_opt, XIP);
 467 #else
 468                         printk("EXT2 xip option not supported\n");
 469 #endif
 470                         break;
 471
 472 #if defined(CONFIG_QUOTA)
 473                 case Opt_quota:
 474                 case Opt_usrquota:
 475                         set_opt(sbi->s_mount_opt, USRQUOTA);
 476                         break;
 477
 478                 case Opt_grpquota:
 479                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 480                         break;
 481 #else
 482                 case Opt_quota:
 483                 case Opt_usrquota:
 484                 case Opt_grpquota:
 485                         printk(KERN_ERR
 486                                 "EXT2-fs: quota operations not supported.\n");
 487
 488                         break;
 489 #endif
 490
 491                 case Opt_ignore:
 492                         break;
 493                 default:
 494                         return 0;
 495                 }
 496         }
 497         return 1;
 498 }
 499
 500 static int ext2_setup_super (struct super_block * sb,
 501                               struct ext2_super_block * es,
 502                               int read_only)
 503 {
 504         int res = 0;
 505         struct ext2_sb_info *sbi = EXT2_SB(sb);
 506
 507         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 508                 printk ("EXT2-fs warning: revision level too high, "
 509                         "forcing read-only mode\n");
 510                 res = MS_RDONLY;
 511         }
 512         if (read_only)
 513                 return res;
 514         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 515                 printk ("EXT2-fs warning: mounting unchecked fs, "
 516                         "running e2fsck is recommended\n");
 517         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 518                 printk ("EXT2-fs warning: mounting fs with errors, "
 519                         "running e2fsck is recommended\n");
 520         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 521                  le16_to_cpu(es->s_mnt_count) >=
 522                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 523                 printk ("EXT2-fs warning: maximal mount count reached, "
 524                         "running e2fsck is recommended\n");
 525         else if (le32_to_cpu(es->s_checkinterval) &&
 526                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 527                 printk ("EXT2-fs warning: checktime reached, "
 528                         "running e2fsck is recommended\n");
 529         if (!le16_to_cpu(es->s_max_mnt_count))
 530                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 531         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 532         ext2_write_super(sb);
 533         if (test_opt (sb, DEBUG))
 534                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 535                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 536                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 537                         sbi->s_frag_size,
 538                         sbi->s_groups_count,
 539                         EXT2_BLOCKS_PER_GROUP(sb),
 540                         EXT2_INODES_PER_GROUP(sb),
 541                         sbi->s_mount_opt);
 542         return res;
 543 }
 544
 545 static int ext2_check_descriptors (struct super_block * sb)
 546 {
 547         int i;
 548         int desc_block = 0;
 549         struct ext2_sb_info *sbi = EXT2_SB(sb);
 550         unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 551         unsigned long last_block;
 552         struct ext2_group_desc * gdp = NULL;
 553
 554         ext2_debug ("Checking group descriptors");
 555
 556         for (i = 0; i < sbi->s_groups_count; i++)
 557         {
 558                 if (i == sbi->s_groups_count - 1)
 559                         last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
 560                 else
 561                         last_block = first_block +
 562                                 (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 563
 564                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 565                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 566                 if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
 567                     le32_to_cpu(gdp->bg_block_bitmap) > last_block)
 568                 {
 569                         ext2_error (sb, "ext2_check_descriptors",
 570                                     "Block bitmap for group %d"
 571                                     " not in group (block %lu)!",
 572                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 573                         return 0;
 574                 }
 575                 if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
 576                     le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
 577                 {
 578                         ext2_error (sb, "ext2_check_descriptors",
 579                                     "Inode bitmap for group %d"
 580                                     " not in group (block %lu)!",
 581                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 582                         return 0;
 583                 }
 584                 if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
 585                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
 586                     last_block)
 587                 {
 588                         ext2_error (sb, "ext2_check_descriptors",
 589                                     "Inode table for group %d"
 590                                     " not in group (block %lu)!",
 591                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 592                         return 0;
 593                 }
 594                 first_block += EXT2_BLOCKS_PER_GROUP(sb);
 595                 gdp++;
 596         }
 597         return 1;
 598 }
 599
 600 /*
 601  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 602  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 603  * We need to be 1 filesystem block less than the 2^32 sector limit.
 604  */
 605 static loff_t ext2_max_size(int bits)
 606 {
 607         loff_t res = EXT2_NDIR_BLOCKS;
 608         /* This constant is calculated to be the largest file size for a
 609          * dense, 4k-blocksize file such that the total number of
 610          * sectors in the file, including data and all indirect blocks,
 611          * does not exceed 2^32. */
 612         const loff_t upper_limit = 0x1ff7fffd000LL;
 613
 614         res += 1LL << (bits-2);
 615         res += 1LL << (2*(bits-2));
 616         res += 1LL << (3*(bits-2));
 617         res <<= bits;
 618         if (res > upper_limit)
 619                 res = upper_limit;
 620         return res;
 621 }
 622
 623 static unsigned long descriptor_loc(struct super_block *sb,
 624                                     unsigned long logic_sb_block,
 625                                     int nr)
 626 {
 627         struct ext2_sb_info *sbi = EXT2_SB(sb);
 628         unsigned long bg, first_data_block, first_meta_bg;
 629         int has_super = 0;
 630
 631         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 632         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 633
 634         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 635             nr < first_meta_bg)
 636                 return (logic_sb_block + nr + 1);
 637         bg = sbi->s_desc_per_block * nr;
 638         if (ext2_bg_has_super(sb, bg))
 639                 has_super = 1;
 640         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 641 }
 642
 643 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 644 {
 645         struct buffer_head * bh;
 646         struct ext2_sb_info * sbi;
 647         struct ext2_super_block * es;
 648         struct inode *root;
 649         unsigned long block;
 650         unsigned long sb_block = get_sb_block(&data);
 651         unsigned long logic_sb_block;
 652         unsigned long offset = 0;
 653         unsigned long def_mount_opts;
 654         int blocksize = BLOCK_SIZE;
 655         int db_count;
 656         int i, j;
 657         __le32 features;
 658
 659         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 660         if (!sbi)
 661                 return -ENOMEM;
 662         sb->s_fs_info = sbi;
 663
 664         /*
 665          * See what the current blocksize for the device is, and
 666          * use that as the blocksize.  Otherwise (or if the blocksize
 667          * is smaller than the default) use the default.
 668          * This is important for devices that have a hardware
 669          * sectorsize that is larger than the default.
 670          */
 671         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 672         if (!blocksize) {
 673                 printk ("EXT2-fs: unable to set blocksize\n");
 674                 goto failed_sbi;
 675         }
 676
 677         /*
 678          * If the superblock doesn't start on a hardware sector boundary,
 679          * calculate the offset.
 680          */
 681         if (blocksize != BLOCK_SIZE) {
 682                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 683                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 684         } else {
 685                 logic_sb_block = sb_block;
 686         }
 687
 688         if (!(bh = sb_bread(sb, logic_sb_block))) {
 689                 printk ("EXT2-fs: unable to read superblock\n");
 690                 goto failed_sbi;
 691         }
 692         /*
 693          * Note: s_es must be initialized as soon as possible because
 694          *       some ext2 macro-instructions depend on its value
 695          */
 696         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 697         sbi->s_es = es;
 698         sb->s_magic = le16_to_cpu(es->s_magic);
 699
 700         if (sb->s_magic != EXT2_SUPER_MAGIC)
 701                 goto cantfind_ext2;
 702
 703         /* Set defaults before we parse the mount options */
 704         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 705         if (def_mount_opts & EXT2_DEFM_DEBUG)
 706                 set_opt(sbi->s_mount_opt, DEBUG);
 707         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 708                 set_opt(sbi->s_mount_opt, GRPID);
 709         if (def_mount_opts & EXT2_DEFM_UID16)
 710                 set_opt(sbi->s_mount_opt, NO_UID32);
 711 #ifdef CONFIG_EXT2_FS_XATTR
 712         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 713                 set_opt(sbi->s_mount_opt, XATTR_USER);
 714 #endif
 715 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 716         if (def_mount_opts & EXT2_DEFM_ACL)
 717                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 718 #endif
 719
 720         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 721                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 722         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 723                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 724         else
 725                 set_opt(sbi->s_mount_opt, ERRORS_CONT);
 726
 727         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 728         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 729
 730         if (!parse_options ((char *) data, sbi))
 731                 goto failed_mount;
 732
 733         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 734                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 735                  MS_POSIXACL : 0);
 736
 737         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 738                                     EXT2_MOUNT_XIP if not */
 739
 740         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 741             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 742              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 743              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 744                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 745                        "running e2fsck is recommended\n");
 746         /*
 747          * Check feature flags regardless of the revision level, since we
 748          * previously didn't change the revision level when setting the flags,
 749          * so there is a chance incompat flags are set on a rev 0 filesystem.
 750          */
 751         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 752         if (features) {
 753                 printk("EXT2-fs: %s: couldn't mount because of "
 754                        "unsupported optional features (%x).\n",
 755                        sb->s_id, le32_to_cpu(features));
 756                 goto failed_mount;
 757         }
 758         if (!(sb->s_flags & MS_RDONLY) &&
 759             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 760                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 761                        "unsupported optional features (%x).\n",
 762                        sb->s_id, le32_to_cpu(features));
 763                 goto failed_mount;
 764         }
 765
 766         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 767
 768         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 769                                   (sb->s_blocksize != blocksize))) {
 770                 if (!silent)
 771                         printk("XIP: Unsupported blocksize\n");
 772                 goto failed_mount;
 773         }
 774
 775         /* If the blocksize doesn't match, re-read the thing.. */
 776         if (sb->s_blocksize != blocksize) {
 777                 brelse(bh);
 778
 779                 if (!sb_set_blocksize(sb, blocksize)) {
 780                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 781                         goto failed_sbi;
 782                 }
 783
 784                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 785                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 786                 bh = sb_bread(sb, logic_sb_block);
 787                 if(!bh) {
 788                         printk("EXT2-fs: Couldn't read superblock on "
 789                                "2nd try.\n");
 790                         goto failed_sbi;
 791                 }
 792                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 793                 sbi->s_es = es;
 794                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 795                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 796                         goto failed_mount;
 797                 }
 798         }
 799
 800         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 801
 802         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 803                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 804                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 805         } else {
 806                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 807                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 808                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 809                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 810                     (sbi->s_inode_size > blocksize)) {
 811                         printk ("EXT2-fs: unsupported inode size: %d\n",
 812                                 sbi->s_inode_size);
 813                         goto failed_mount;
 814                 }
 815         }
 816
 817         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 818                                    le32_to_cpu(es->s_log_frag_size);
 819         if (sbi->s_frag_size == 0)
 820                 goto cantfind_ext2;
 821         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 822
 823         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 824         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 825         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 826
 827         if (EXT2_INODE_SIZE(sb) == 0)
 828                 goto cantfind_ext2;
 829         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 830         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
 831                 goto cantfind_ext2;
 832         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 833                                         sbi->s_inodes_per_block;
 834         sbi->s_desc_per_block = sb->s_blocksize /
 835                                         sizeof (struct ext2_group_desc);
 836         sbi->s_sbh = bh;
 837         sbi->s_mount_state = le16_to_cpu(es->s_state);
 838         sbi->s_addr_per_block_bits =
 839                 ilog2 (EXT2_ADDR_PER_BLOCK(sb));
 840         sbi->s_desc_per_block_bits =
 841                 ilog2 (EXT2_DESC_PER_BLOCK(sb));
 842
 843         if (sb->s_magic != EXT2_SUPER_MAGIC)
 844                 goto cantfind_ext2;
 845
 846         if (sb->s_blocksize != bh->b_size) {
 847                 if (!silent)
 848                         printk ("VFS: Unsupported blocksize on dev "
 849                                 "%s.\n", sb->s_id);
 850                 goto failed_mount;
 851         }
 852
 853         if (sb->s_blocksize != sbi->s_frag_size) {
 854                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 855                         sbi->s_frag_size, sb->s_blocksize);
 856                 goto failed_mount;
 857         }
 858
 859         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 860                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 861                         sbi->s_blocks_per_group);
 862                 goto failed_mount;
 863         }
 864         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 865                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 866                         sbi->s_frags_per_group);
 867                 goto failed_mount;
 868         }
 869         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 870                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 871                         sbi->s_inodes_per_group);
 872                 goto failed_mount;
 873         }
 874
 875         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 876                 goto cantfind_ext2;
 877         sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
 878                                 le32_to_cpu(es->s_first_data_block) - 1)
 879                                         / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
 880         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 881                    EXT2_DESC_PER_BLOCK(sb);
 882         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 883         if (sbi->s_group_desc == NULL) {
 884                 printk ("EXT2-fs: not enough memory\n");
 885                 goto failed_mount;
 886         }
 887         bgl_lock_init(&sbi->s_blockgroup_lock);
 888         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 889                                GFP_KERNEL);
 890         if (!sbi->s_debts) {
 891                 printk ("EXT2-fs: not enough memory\n");
 892                 goto failed_mount_group_desc;
 893         }
 894         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 895         for (i = 0; i < db_count; i++) {
 896                 block = descriptor_loc(sb, logic_sb_block, i);
 897                 sbi->s_group_desc[i] = sb_bread(sb, block);
 898                 if (!sbi->s_group_desc[i]) {
 899                         for (j = 0; j < i; j++)
 900                                 brelse (sbi->s_group_desc[j]);
 901                         printk ("EXT2-fs: unable to read group descriptors\n");
 902                         goto failed_mount_group_desc;
 903                 }
 904         }
 905         if (!ext2_check_descriptors (sb)) {
 906                 printk ("EXT2-fs: group descriptors corrupted!\n");
 907                 goto failed_mount2;
 908         }
 909         sbi->s_gdb_count = db_count;
 910         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 911         spin_lock_init(&sbi->s_next_gen_lock);
 912
 913         percpu_counter_init(&sbi->s_freeblocks_counter,
 914                                 ext2_count_free_blocks(sb));
 915         percpu_counter_init(&sbi->s_freeinodes_counter,
 916                                 ext2_count_free_inodes(sb));
 917         percpu_counter_init(&sbi->s_dirs_counter,
 918                                 ext2_count_dirs(sb));
 919         /*
 920          * set up enough so that it can read an inode
 921          */
 922         sb->s_op = &ext2_sops;
 923         sb->s_export_op = &ext2_export_ops;
 924         sb->s_xattr = ext2_xattr_handlers;
 925         root = iget(sb, EXT2_ROOT_INO);
 926         sb->s_root = d_alloc_root(root);
 927         if (!sb->s_root) {
 928                 iput(root);
 929                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 930                 goto failed_mount3;
 931         }
 932         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 933                 dput(sb->s_root);
 934                 sb->s_root = NULL;
 935                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 936                 goto failed_mount3;
 937         }
 938         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 939                 ext2_warning(sb, __FUNCTION__,
 940                         "mounting ext3 filesystem as ext2");
 941         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 942         return 0;
 943
 944 cantfind_ext2:
 945         if (!silent)
 946                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 947                        sb->s_id);
 948         goto failed_mount;
 949 failed_mount3:
 950         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 951         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 952         percpu_counter_destroy(&sbi->s_dirs_counter);
 953 failed_mount2:
 954         for (i = 0; i < db_count; i++)
 955                 brelse(sbi->s_group_desc[i]);
 956 failed_mount_group_desc:
 957         kfree(sbi->s_group_desc);
 958         kfree(sbi->s_debts);
 959 failed_mount:
 960         brelse(bh);
 961 failed_sbi:
 962         sb->s_fs_info = NULL;
 963         kfree(sbi);
 964         return -EINVAL;
 965 }
 966
 967 static void ext2_commit_super (struct super_block * sb,
 968                                struct ext2_super_block * es)
 969 {
 970         es->s_wtime = cpu_to_le32(get_seconds());
 971         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 972         sb->s_dirt = 0;
 973 }
 974
 975 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 976 {
 977         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 978         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 979         es->s_wtime = cpu_to_le32(get_seconds());
 980         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 981         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 982         sb->s_dirt = 0;
 983 }
 984
 985 /*
 986  * In the second extended file system, it is not necessary to
 987  * write the super block since we use a mapping of the
 988  * disk super block in a buffer.
 989  *
 990  * However, this function is still used to set the fs valid
 991  * flags to 0.  We need to set this flag to 0 since the fs
 992  * may have been checked while mounted and e2fsck may have
 993  * set s_state to EXT2_VALID_FS after some corrections.
 994  */
 995
 996 void ext2_write_super (struct super_block * sb)
 997 {
 998         struct ext2_super_block * es;
 999         lock_kernel();
1000         if (!(sb->s_flags & MS_RDONLY)) {
1001                 es = EXT2_SB(sb)->s_es;
1002
1003                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1004                         ext2_debug ("setting valid to 0\n");
1005                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1006                                                   ~EXT2_VALID_FS);
1007                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1008                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1009                         es->s_mtime = cpu_to_le32(get_seconds());
1010                         ext2_sync_super(sb, es);
1011                 } else
1012                         ext2_commit_super (sb, es);
1013         }
1014         sb->s_dirt = 0;
1015         unlock_kernel();
1016 }
1017
1018 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1019 {
1020         struct ext2_sb_info * sbi = EXT2_SB(sb);
1021         struct ext2_super_block * es;
1022         unsigned long old_mount_opt = sbi->s_mount_opt;
1023         struct ext2_mount_options old_opts;
1024         unsigned long old_sb_flags;
1025         int err;
1026
1027         /* Store the old options */
1028         old_sb_flags = sb->s_flags;
1029         old_opts.s_mount_opt = sbi->s_mount_opt;
1030         old_opts.s_resuid = sbi->s_resuid;
1031         old_opts.s_resgid = sbi->s_resgid;
1032
1033         /*
1034          * Allow the "check" option to be passed as a remount option.
1035          */
1036         if (!parse_options (data, sbi)) {
1037                 err = -EINVAL;
1038                 goto restore_opts;
1039         }
1040
1041         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1042                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1043
1044         es = sbi->s_es;
1045         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1046             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1047             invalidate_inodes(sb))
1048                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1049                              "xip remain in cache (no functional problem)");
1050         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1051                 return 0;
1052         if (*flags & MS_RDONLY) {
1053                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1054                     !(sbi->s_mount_state & EXT2_VALID_FS))
1055                         return 0;
1056                 /*
1057                  * OK, we are remounting a valid rw partition rdonly, so set
1058                  * the rdonly flag and then mark the partition as valid again.
1059                  */
1060                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1061                 es->s_mtime = cpu_to_le32(get_seconds());
1062         } else {
1063                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1064                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1065                 if (ret) {
1066                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1067                                "unsupported optional features (%x).\n",
1068                                sb->s_id, le32_to_cpu(ret));
1069                         err = -EROFS;
1070                         goto restore_opts;
1071                 }
1072                 /*
1073                  * Mounting a RDONLY partition read-write, so reread and
1074                  * store the current valid flag.  (It may have been changed
1075                  * by e2fsck since we originally mounted the partition.)
1076                  */
1077                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1078                 if (!ext2_setup_super (sb, es, 0))
1079                         sb->s_flags &= ~MS_RDONLY;
1080         }
1081         ext2_sync_super(sb, es);
1082         return 0;
1083 restore_opts:
1084         sbi->s_mount_opt = old_opts.s_mount_opt;
1085         sbi->s_resuid = old_opts.s_resuid;
1086         sbi->s_resgid = old_opts.s_resgid;
1087         sb->s_flags = old_sb_flags;
1088         return err;
1089 }
1090
1091 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1092 {
1093         struct super_block *sb = dentry->d_sb;
1094         struct ext2_sb_info *sbi = EXT2_SB(sb);
1095         struct ext2_super_block *es = sbi->s_es;
1096         unsigned long overhead;
1097         int i;
1098         u64 fsid;
1099
1100         if (test_opt (sb, MINIX_DF))
1101                 overhead = 0;
1102         else {
1103                 /*
1104                  * Compute the overhead (FS structures)
1105                  */
1106
1107                 /*
1108                  * All of the blocks before first_data_block are
1109                  * overhead
1110                  */
1111                 overhead = le32_to_cpu(es->s_first_data_block);
1112
1113                 /*
1114                  * Add the overhead attributed to the superblock and
1115                  * block group descriptors.  If the sparse superblocks
1116                  * feature is turned on, then not all groups have this.
1117                  */
1118                 for (i = 0; i < sbi->s_groups_count; i++)
1119                         overhead += ext2_bg_has_super(sb, i) +
1120                                 ext2_bg_num_gdb(sb, i);
1121
1122                 /*
1123                  * Every block group has an inode bitmap, a block
1124                  * bitmap, and an inode table.
1125                  */
1126                 overhead += (sbi->s_groups_count *
1127                              (2 + sbi->s_itb_per_group));
1128         }
1129
1130         buf->f_type = EXT2_SUPER_MAGIC;
1131         buf->f_bsize = sb->s_blocksize;
1132         buf->f_blocks = le32_to_cpu(es->s_blocks_count) - overhead;
1133         buf->f_bfree = ext2_count_free_blocks(sb);
1134         buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
1135         if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
1136                 buf->f_bavail = 0;
1137         buf->f_files = le32_to_cpu(es->s_inodes_count);
1138         buf->f_ffree = ext2_count_free_inodes(sb);
1139         buf->f_namelen = EXT2_NAME_LEN;
1140         fsid = le64_to_cpup((void *)es->s_uuid) ^
1141                le64_to_cpup((void *)es->s_uuid + sizeof(u64));
1142         buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
1143         buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
1144         return 0;
1145 }
1146
1147 static int ext2_get_sb(struct file_system_type *fs_type,
1148         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1149 {
1150         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1151 }
1152
1153 #ifdef CONFIG_QUOTA
1154
1155 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1156  * acquiring the locks... As quota files are never truncated and quota code
1157  * itself serializes the operations (and noone else should touch the files)
1158  * we don't have to be afraid of races */
1159 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1160                                size_t len, loff_t off)
1161 {
1162         struct inode *inode = sb_dqopt(sb)->files[type];
1163         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1164         int err = 0;
1165         int offset = off & (sb->s_blocksize - 1);
1166         int tocopy;
1167         size_t toread;
1168         struct buffer_head tmp_bh;
1169         struct buffer_head *bh;
1170         loff_t i_size = i_size_read(inode);
1171
1172         if (off > i_size)
1173                 return 0;
1174         if (off+len > i_size)
1175                 len = i_size-off;
1176         toread = len;
1177         while (toread > 0) {
1178                 tocopy = sb->s_blocksize - offset < toread ?
1179                                 sb->s_blocksize - offset : toread;
1180
1181                 tmp_bh.b_state = 0;
1182                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1183                 if (err)
1184                         return err;
1185                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1186                         memset(data, 0, tocopy);
1187                 else {
1188                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1189                         if (!bh)
1190                                 return -EIO;
1191                         memcpy(data, bh->b_data+offset, tocopy);
1192                         brelse(bh);
1193                 }
1194                 offset = 0;
1195                 toread -= tocopy;
1196                 data += tocopy;
1197                 blk++;
1198         }
1199         return len;
1200 }
1201
1202 /* Write to quotafile */
1203 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1204                                 const char *data, size_t len, loff_t off)
1205 {
1206         struct inode *inode = sb_dqopt(sb)->files[type];
1207         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1208         int err = 0;
1209         int offset = off & (sb->s_blocksize - 1);
1210         int tocopy;
1211         size_t towrite = len;
1212         struct buffer_head tmp_bh;
1213         struct buffer_head *bh;
1214
1215         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1216         while (towrite > 0) {
1217                 tocopy = sb->s_blocksize - offset < towrite ?
1218                                 sb->s_blocksize - offset : towrite;
1219
1220                 tmp_bh.b_state = 0;
1221                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1222                 if (err)
1223                         goto out;
1224                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1225                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1226                 else
1227                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1228                 if (!bh) {
1229                         err = -EIO;
1230                         goto out;
1231                 }
1232                 lock_buffer(bh);
1233                 memcpy(bh->b_data+offset, data, tocopy);
1234                 flush_dcache_page(bh->b_page);
1235                 set_buffer_uptodate(bh);
1236                 mark_buffer_dirty(bh);
1237                 unlock_buffer(bh);
1238                 brelse(bh);
1239                 offset = 0;
1240                 towrite -= tocopy;
1241                 data += tocopy;
1242                 blk++;
1243         }
1244 out:
1245         if (len == towrite)
1246                 return err;
1247         if (inode->i_size < off+len-towrite)
1248                 i_size_write(inode, off+len-towrite);
1249         inode->i_version++;
1250         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1251         mark_inode_dirty(inode);
1252         mutex_unlock(&inode->i_mutex);
1253         return len - towrite;
1254 }
1255
1256 #endif
1257
1258 static struct file_system_type ext2_fs_type = {
1259         .owner          = THIS_MODULE,
1260         .name           = "ext2",
1261         .get_sb         = ext2_get_sb,
1262         .kill_sb        = kill_block_super,
1263         .fs_flags       = FS_REQUIRES_DEV,
1264 };
1265
1266 static int __init init_ext2_fs(void)
1267 {
1268         int err = init_ext2_xattr();
1269         if (err)
1270                 return err;
1271         err = init_inodecache();
1272         if (err)
1273                 goto out1;
1274         err = register_filesystem(&ext2_fs_type);
1275         if (err)
1276                 goto out;
1277         return 0;
1278 out:
1279         destroy_inodecache();
1280 out1:
1281         exit_ext2_xattr();
1282         return err;
1283 }
1284
1285 static void __exit exit_ext2_fs(void)
1286 {
1287         unregister_filesystem(&ext2_fs_type);
1288         destroy_inodecache();
1289         exit_ext2_xattr();
1290 }
1291
1292 module_init(init_ext2_fs)
1293 module_exit(exit_ext2_fs)