git.oblomov.eu Git - linux-2.6/blob - 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 kmem_cache_t * 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, SLAB_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, kmem_cache_t * 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         if (kmem_cache_destroy(ext2_inode_cachep))
 188                 printk(KERN_INFO "ext2_inode_cache: not all structures were freed\n");
 189 }
 190
 191 static void ext2_clear_inode(struct inode *inode)
 192 {
 193 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 194         struct ext2_inode_info *ei = EXT2_I(inode);
 195
 196         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
 197                 posix_acl_release(ei->i_acl);
 198                 ei->i_acl = EXT2_ACL_NOT_CACHED;
 199         }
 200         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
 201                 posix_acl_release(ei->i_default_acl);
 202                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 203         }
 204 #endif
 205 }
 206
 207 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
 208 {
 209         struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
 210
 211         if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
 212                 seq_puts(seq, ",grpid");
 213
 214 #if defined(CONFIG_QUOTA)
 215         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
 216                 seq_puts(seq, ",usrquota");
 217
 218         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
 219                 seq_puts(seq, ",grpquota");
 220 #endif
 221
 222 #if defined(CONFIG_EXT2_FS_XIP)
 223         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
 224                 seq_puts(seq, ",xip");
 225 #endif
 226
 227         return 0;
 228 }
 229
 230 #ifdef CONFIG_QUOTA
 231 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
 232 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
 233 #endif
 234
 235 static struct super_operations ext2_sops = {
 236         .alloc_inode    = ext2_alloc_inode,
 237         .destroy_inode  = ext2_destroy_inode,
 238         .read_inode     = ext2_read_inode,
 239         .write_inode    = ext2_write_inode,
 240         .put_inode      = ext2_put_inode,
 241         .delete_inode   = ext2_delete_inode,
 242         .put_super      = ext2_put_super,
 243         .write_super    = ext2_write_super,
 244         .statfs         = ext2_statfs,
 245         .remount_fs     = ext2_remount,
 246         .clear_inode    = ext2_clear_inode,
 247         .show_options   = ext2_show_options,
 248 #ifdef CONFIG_QUOTA
 249         .quota_read     = ext2_quota_read,
 250         .quota_write    = ext2_quota_write,
 251 #endif
 252 };
 253
 254 /* Yes, most of these are left as NULL!!
 255  * A NULL value implies the default, which works with ext2-like file
 256  * systems, but can be improved upon.
 257  * Currently only get_parent is required.
 258  */
 259 static struct export_operations ext2_export_ops = {
 260         .get_parent = ext2_get_parent,
 261 };
 262
 263 static unsigned long get_sb_block(void **data)
 264 {
 265         unsigned long   sb_block;
 266         char            *options = (char *) *data;
 267
 268         if (!options || strncmp(options, "sb=", 3) != 0)
 269                 return 1;       /* Default location */
 270         options += 3;
 271         sb_block = simple_strtoul(options, &options, 0);
 272         if (*options && *options != ',') {
 273                 printk("EXT2-fs: Invalid sb specification: %s\n",
 274                        (char *) *data);
 275                 return 1;
 276         }
 277         if (*options == ',')
 278                 options++;
 279         *data = (void *) options;
 280         return sb_block;
 281 }
 282
 283 enum {
 284         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 285         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
 286         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
 287         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
 288         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
 289         Opt_usrquota, Opt_grpquota
 290 };
 291
 292 static match_table_t tokens = {
 293         {Opt_bsd_df, "bsddf"},
 294         {Opt_minix_df, "minixdf"},
 295         {Opt_grpid, "grpid"},
 296         {Opt_grpid, "bsdgroups"},
 297         {Opt_nogrpid, "nogrpid"},
 298         {Opt_nogrpid, "sysvgroups"},
 299         {Opt_resgid, "resgid=%u"},
 300         {Opt_resuid, "resuid=%u"},
 301         {Opt_sb, "sb=%u"},
 302         {Opt_err_cont, "errors=continue"},
 303         {Opt_err_panic, "errors=panic"},
 304         {Opt_err_ro, "errors=remount-ro"},
 305         {Opt_nouid32, "nouid32"},
 306         {Opt_nocheck, "check=none"},
 307         {Opt_nocheck, "nocheck"},
 308         {Opt_debug, "debug"},
 309         {Opt_oldalloc, "oldalloc"},
 310         {Opt_orlov, "orlov"},
 311         {Opt_nobh, "nobh"},
 312         {Opt_user_xattr, "user_xattr"},
 313         {Opt_nouser_xattr, "nouser_xattr"},
 314         {Opt_acl, "acl"},
 315         {Opt_noacl, "noacl"},
 316         {Opt_xip, "xip"},
 317         {Opt_grpquota, "grpquota"},
 318         {Opt_ignore, "noquota"},
 319         {Opt_quota, "quota"},
 320         {Opt_usrquota, "usrquota"},
 321         {Opt_err, NULL}
 322 };
 323
 324 static int parse_options (char * options,
 325                           struct ext2_sb_info *sbi)
 326 {
 327         char * p;
 328         substring_t args[MAX_OPT_ARGS];
 329         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 330         int option;
 331
 332         if (!options)
 333                 return 1;
 334
 335         while ((p = strsep (&options, ",")) != NULL) {
 336                 int token;
 337                 if (!*p)
 338                         continue;
 339
 340                 token = match_token(p, tokens, args);
 341                 switch (token) {
 342                 case Opt_bsd_df:
 343                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 344                         break;
 345                 case Opt_minix_df:
 346                         set_opt (sbi->s_mount_opt, MINIX_DF);
 347                         break;
 348                 case Opt_grpid:
 349                         set_opt (sbi->s_mount_opt, GRPID);
 350                         break;
 351                 case Opt_nogrpid:
 352                         clear_opt (sbi->s_mount_opt, GRPID);
 353                         break;
 354                 case Opt_resuid:
 355                         if (match_int(&args[0], &option))
 356                                 return 0;
 357                         sbi->s_resuid = option;
 358                         break;
 359                 case Opt_resgid:
 360                         if (match_int(&args[0], &option))
 361                                 return 0;
 362                         sbi->s_resgid = option;
 363                         break;
 364                 case Opt_sb:
 365                         /* handled by get_sb_block() instead of here */
 366                         /* *sb_block = match_int(&args[0]); */
 367                         break;
 368                 case Opt_err_panic:
 369                         kind = EXT2_MOUNT_ERRORS_PANIC;
 370                         break;
 371                 case Opt_err_ro:
 372                         kind = EXT2_MOUNT_ERRORS_RO;
 373                         break;
 374                 case Opt_err_cont:
 375                         kind = EXT2_MOUNT_ERRORS_CONT;
 376                         break;
 377                 case Opt_nouid32:
 378                         set_opt (sbi->s_mount_opt, NO_UID32);
 379                         break;
 380                 case Opt_nocheck:
 381                         clear_opt (sbi->s_mount_opt, CHECK);
 382                         break;
 383                 case Opt_debug:
 384                         set_opt (sbi->s_mount_opt, DEBUG);
 385                         break;
 386                 case Opt_oldalloc:
 387                         set_opt (sbi->s_mount_opt, OLDALLOC);
 388                         break;
 389                 case Opt_orlov:
 390                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 391                         break;
 392                 case Opt_nobh:
 393                         set_opt (sbi->s_mount_opt, NOBH);
 394                         break;
 395 #ifdef CONFIG_EXT2_FS_XATTR
 396                 case Opt_user_xattr:
 397                         set_opt (sbi->s_mount_opt, XATTR_USER);
 398                         break;
 399                 case Opt_nouser_xattr:
 400                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 401                         break;
 402 #else
 403                 case Opt_user_xattr:
 404                 case Opt_nouser_xattr:
 405                         printk("EXT2 (no)user_xattr options not supported\n");
 406                         break;
 407 #endif
 408 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 409                 case Opt_acl:
 410                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 411                         break;
 412                 case Opt_noacl:
 413                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 414                         break;
 415 #else
 416                 case Opt_acl:
 417                 case Opt_noacl:
 418                         printk("EXT2 (no)acl options not supported\n");
 419                         break;
 420 #endif
 421                 case Opt_xip:
 422 #ifdef CONFIG_EXT2_FS_XIP
 423                         set_opt (sbi->s_mount_opt, XIP);
 424 #else
 425                         printk("EXT2 xip option not supported\n");
 426 #endif
 427                         break;
 428
 429 #if defined(CONFIG_QUOTA)
 430                 case Opt_quota:
 431                 case Opt_usrquota:
 432                         set_opt(sbi->s_mount_opt, USRQUOTA);
 433                         break;
 434
 435                 case Opt_grpquota:
 436                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 437                         break;
 438 #else
 439                 case Opt_quota:
 440                 case Opt_usrquota:
 441                 case Opt_grpquota:
 442                         printk(KERN_ERR
 443                                 "EXT2-fs: quota operations not supported.\n");
 444
 445                         break;
 446 #endif
 447
 448                 case Opt_ignore:
 449                         break;
 450                 default:
 451                         return 0;
 452                 }
 453         }
 454         sbi->s_mount_opt |= kind;
 455         return 1;
 456 }
 457
 458 static int ext2_setup_super (struct super_block * sb,
 459                               struct ext2_super_block * es,
 460                               int read_only)
 461 {
 462         int res = 0;
 463         struct ext2_sb_info *sbi = EXT2_SB(sb);
 464
 465         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 466                 printk ("EXT2-fs warning: revision level too high, "
 467                         "forcing read-only mode\n");
 468                 res = MS_RDONLY;
 469         }
 470         if (read_only)
 471                 return res;
 472         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 473                 printk ("EXT2-fs warning: mounting unchecked fs, "
 474                         "running e2fsck is recommended\n");
 475         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 476                 printk ("EXT2-fs warning: mounting fs with errors, "
 477                         "running e2fsck is recommended\n");
 478         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 479                  le16_to_cpu(es->s_mnt_count) >=
 480                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 481                 printk ("EXT2-fs warning: maximal mount count reached, "
 482                         "running e2fsck is recommended\n");
 483         else if (le32_to_cpu(es->s_checkinterval) &&
 484                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 485                 printk ("EXT2-fs warning: checktime reached, "
 486                         "running e2fsck is recommended\n");
 487         if (!le16_to_cpu(es->s_max_mnt_count))
 488                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 489         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 490         ext2_write_super(sb);
 491         if (test_opt (sb, DEBUG))
 492                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 493                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 494                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 495                         sbi->s_frag_size,
 496                         sbi->s_groups_count,
 497                         EXT2_BLOCKS_PER_GROUP(sb),
 498                         EXT2_INODES_PER_GROUP(sb),
 499                         sbi->s_mount_opt);
 500         return res;
 501 }
 502
 503 static int ext2_check_descriptors (struct super_block * sb)
 504 {
 505         int i;
 506         int desc_block = 0;
 507         struct ext2_sb_info *sbi = EXT2_SB(sb);
 508         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
 509         struct ext2_group_desc * gdp = NULL;
 510
 511         ext2_debug ("Checking group descriptors");
 512
 513         for (i = 0; i < sbi->s_groups_count; i++)
 514         {
 515                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 516                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 517                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
 518                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 519                 {
 520                         ext2_error (sb, "ext2_check_descriptors",
 521                                     "Block bitmap for group %d"
 522                                     " not in group (block %lu)!",
 523                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 524                         return 0;
 525                 }
 526                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
 527                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 528                 {
 529                         ext2_error (sb, "ext2_check_descriptors",
 530                                     "Inode bitmap for group %d"
 531                                     " not in group (block %lu)!",
 532                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 533                         return 0;
 534                 }
 535                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
 536                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
 537                     block + EXT2_BLOCKS_PER_GROUP(sb))
 538                 {
 539                         ext2_error (sb, "ext2_check_descriptors",
 540                                     "Inode table for group %d"
 541                                     " not in group (block %lu)!",
 542                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 543                         return 0;
 544                 }
 545                 block += EXT2_BLOCKS_PER_GROUP(sb);
 546                 gdp++;
 547         }
 548         return 1;
 549 }
 550
 551 #define log2(n) ffz(~(n))
 552
 553 /*
 554  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 555  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 556  * We need to be 1 filesystem block less than the 2^32 sector limit.
 557  */
 558 static loff_t ext2_max_size(int bits)
 559 {
 560         loff_t res = EXT2_NDIR_BLOCKS;
 561         /* This constant is calculated to be the largest file size for a
 562          * dense, 4k-blocksize file such that the total number of
 563          * sectors in the file, including data and all indirect blocks,
 564          * does not exceed 2^32. */
 565         const loff_t upper_limit = 0x1ff7fffd000LL;
 566
 567         res += 1LL << (bits-2);
 568         res += 1LL << (2*(bits-2));
 569         res += 1LL << (3*(bits-2));
 570         res <<= bits;
 571         if (res > upper_limit)
 572                 res = upper_limit;
 573         return res;
 574 }
 575
 576 static unsigned long descriptor_loc(struct super_block *sb,
 577                                     unsigned long logic_sb_block,
 578                                     int nr)
 579 {
 580         struct ext2_sb_info *sbi = EXT2_SB(sb);
 581         unsigned long bg, first_data_block, first_meta_bg;
 582         int has_super = 0;
 583
 584         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 585         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 586
 587         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 588             nr < first_meta_bg)
 589                 return (logic_sb_block + nr + 1);
 590         bg = sbi->s_desc_per_block * nr;
 591         if (ext2_bg_has_super(sb, bg))
 592                 has_super = 1;
 593         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 594 }
 595
 596 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 597 {
 598         struct buffer_head * bh;
 599         struct ext2_sb_info * sbi;
 600         struct ext2_super_block * es;
 601         struct inode *root;
 602         unsigned long block;
 603         unsigned long sb_block = get_sb_block(&data);
 604         unsigned long logic_sb_block;
 605         unsigned long offset = 0;
 606         unsigned long def_mount_opts;
 607         int blocksize = BLOCK_SIZE;
 608         int db_count;
 609         int i, j;
 610         __le32 features;
 611
 612         sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
 613         if (!sbi)
 614                 return -ENOMEM;
 615         sb->s_fs_info = sbi;
 616         memset(sbi, 0, sizeof(*sbi));
 617
 618         /*
 619          * See what the current blocksize for the device is, and
 620          * use that as the blocksize.  Otherwise (or if the blocksize
 621          * is smaller than the default) use the default.
 622          * This is important for devices that have a hardware
 623          * sectorsize that is larger than the default.
 624          */
 625         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 626         if (!blocksize) {
 627                 printk ("EXT2-fs: unable to set blocksize\n");
 628                 goto failed_sbi;
 629         }
 630
 631         /*
 632          * If the superblock doesn't start on a hardware sector boundary,
 633          * calculate the offset.
 634          */
 635         if (blocksize != BLOCK_SIZE) {
 636                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 637                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 638         } else {
 639                 logic_sb_block = sb_block;
 640         }
 641
 642         if (!(bh = sb_bread(sb, logic_sb_block))) {
 643                 printk ("EXT2-fs: unable to read superblock\n");
 644                 goto failed_sbi;
 645         }
 646         /*
 647          * Note: s_es must be initialized as soon as possible because
 648          *       some ext2 macro-instructions depend on its value
 649          */
 650         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 651         sbi->s_es = es;
 652         sb->s_magic = le16_to_cpu(es->s_magic);
 653
 654         if (sb->s_magic != EXT2_SUPER_MAGIC)
 655                 goto cantfind_ext2;
 656
 657         /* Set defaults before we parse the mount options */
 658         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 659         if (def_mount_opts & EXT2_DEFM_DEBUG)
 660                 set_opt(sbi->s_mount_opt, DEBUG);
 661         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 662                 set_opt(sbi->s_mount_opt, GRPID);
 663         if (def_mount_opts & EXT2_DEFM_UID16)
 664                 set_opt(sbi->s_mount_opt, NO_UID32);
 665         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 666                 set_opt(sbi->s_mount_opt, XATTR_USER);
 667         if (def_mount_opts & EXT2_DEFM_ACL)
 668                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 669
 670         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 671                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 672         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 673                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 674
 675         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 676         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 677
 678         if (!parse_options ((char *) data, sbi))
 679                 goto failed_mount;
 680
 681         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 682                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 683                  MS_POSIXACL : 0);
 684
 685         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 686                                     EXT2_MOUNT_XIP if not */
 687
 688         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 689             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 690              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 691              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 692                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 693                        "running e2fsck is recommended\n");
 694         /*
 695          * Check feature flags regardless of the revision level, since we
 696          * previously didn't change the revision level when setting the flags,
 697          * so there is a chance incompat flags are set on a rev 0 filesystem.
 698          */
 699         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 700         if (features) {
 701                 printk("EXT2-fs: %s: couldn't mount because of "
 702                        "unsupported optional features (%x).\n",
 703                        sb->s_id, le32_to_cpu(features));
 704                 goto failed_mount;
 705         }
 706         if (!(sb->s_flags & MS_RDONLY) &&
 707             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 708                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 709                        "unsupported optional features (%x).\n",
 710                        sb->s_id, le32_to_cpu(features));
 711                 goto failed_mount;
 712         }
 713
 714         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 715
 716         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 717                                   (sb->s_blocksize != blocksize))) {
 718                 if (!silent)
 719                         printk("XIP: Unsupported blocksize\n");
 720                 goto failed_mount;
 721         }
 722
 723         /* If the blocksize doesn't match, re-read the thing.. */
 724         if (sb->s_blocksize != blocksize) {
 725                 brelse(bh);
 726
 727                 if (!sb_set_blocksize(sb, blocksize)) {
 728                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 729                         goto failed_sbi;
 730                 }
 731
 732                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 733                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 734                 bh = sb_bread(sb, logic_sb_block);
 735                 if(!bh) {
 736                         printk("EXT2-fs: Couldn't read superblock on "
 737                                "2nd try.\n");
 738                         goto failed_sbi;
 739                 }
 740                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 741                 sbi->s_es = es;
 742                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 743                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 744                         goto failed_mount;
 745                 }
 746         }
 747
 748         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 749
 750         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 751                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 752                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 753         } else {
 754                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 755                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 756                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 757                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 758                     (sbi->s_inode_size > blocksize)) {
 759                         printk ("EXT2-fs: unsupported inode size: %d\n",
 760                                 sbi->s_inode_size);
 761                         goto failed_mount;
 762                 }
 763         }
 764
 765         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 766                                    le32_to_cpu(es->s_log_frag_size);
 767         if (sbi->s_frag_size == 0)
 768                 goto cantfind_ext2;
 769         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 770
 771         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 772         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 773         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 774
 775         if (EXT2_INODE_SIZE(sb) == 0)
 776                 goto cantfind_ext2;
 777         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 778         if (sbi->s_inodes_per_block == 0)
 779                 goto cantfind_ext2;
 780         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 781                                         sbi->s_inodes_per_block;
 782         sbi->s_desc_per_block = sb->s_blocksize /
 783                                         sizeof (struct ext2_group_desc);
 784         sbi->s_sbh = bh;
 785         sbi->s_mount_state = le16_to_cpu(es->s_state);
 786         sbi->s_addr_per_block_bits =
 787                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 788         sbi->s_desc_per_block_bits =
 789                 log2 (EXT2_DESC_PER_BLOCK(sb));
 790
 791         if (sb->s_magic != EXT2_SUPER_MAGIC)
 792                 goto cantfind_ext2;
 793
 794         if (sb->s_blocksize != bh->b_size) {
 795                 if (!silent)
 796                         printk ("VFS: Unsupported blocksize on dev "
 797                                 "%s.\n", sb->s_id);
 798                 goto failed_mount;
 799         }
 800
 801         if (sb->s_blocksize != sbi->s_frag_size) {
 802                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 803                         sbi->s_frag_size, sb->s_blocksize);
 804                 goto failed_mount;
 805         }
 806
 807         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 808                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 809                         sbi->s_blocks_per_group);
 810                 goto failed_mount;
 811         }
 812         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 813                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 814                         sbi->s_frags_per_group);
 815                 goto failed_mount;
 816         }
 817         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 818                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 819                         sbi->s_inodes_per_group);
 820                 goto failed_mount;
 821         }
 822
 823         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 824                 goto cantfind_ext2;
 825         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
 826                                         le32_to_cpu(es->s_first_data_block) +
 827                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 828                                        EXT2_BLOCKS_PER_GROUP(sb);
 829         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 830                    EXT2_DESC_PER_BLOCK(sb);
 831         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 832         if (sbi->s_group_desc == NULL) {
 833                 printk ("EXT2-fs: not enough memory\n");
 834                 goto failed_mount;
 835         }
 836         bgl_lock_init(&sbi->s_blockgroup_lock);
 837         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 838                                GFP_KERNEL);
 839         if (!sbi->s_debts) {
 840                 printk ("EXT2-fs: not enough memory\n");
 841                 goto failed_mount_group_desc;
 842         }
 843         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 844         for (i = 0; i < db_count; i++) {
 845                 block = descriptor_loc(sb, logic_sb_block, i);
 846                 sbi->s_group_desc[i] = sb_bread(sb, block);
 847                 if (!sbi->s_group_desc[i]) {
 848                         for (j = 0; j < i; j++)
 849                                 brelse (sbi->s_group_desc[j]);
 850                         printk ("EXT2-fs: unable to read group descriptors\n");
 851                         goto failed_mount_group_desc;
 852                 }
 853         }
 854         if (!ext2_check_descriptors (sb)) {
 855                 printk ("EXT2-fs: group descriptors corrupted!\n");
 856                 goto failed_mount2;
 857         }
 858         sbi->s_gdb_count = db_count;
 859         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 860         spin_lock_init(&sbi->s_next_gen_lock);
 861
 862         percpu_counter_init(&sbi->s_freeblocks_counter,
 863                                 ext2_count_free_blocks(sb));
 864         percpu_counter_init(&sbi->s_freeinodes_counter,
 865                                 ext2_count_free_inodes(sb));
 866         percpu_counter_init(&sbi->s_dirs_counter,
 867                                 ext2_count_dirs(sb));
 868         /*
 869          * set up enough so that it can read an inode
 870          */
 871         sb->s_op = &ext2_sops;
 872         sb->s_export_op = &ext2_export_ops;
 873         sb->s_xattr = ext2_xattr_handlers;
 874         root = iget(sb, EXT2_ROOT_INO);
 875         sb->s_root = d_alloc_root(root);
 876         if (!sb->s_root) {
 877                 iput(root);
 878                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 879                 goto failed_mount3;
 880         }
 881         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 882                 dput(sb->s_root);
 883                 sb->s_root = NULL;
 884                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 885                 goto failed_mount3;
 886         }
 887         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 888                 ext2_warning(sb, __FUNCTION__,
 889                         "mounting ext3 filesystem as ext2");
 890         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 891         return 0;
 892
 893 cantfind_ext2:
 894         if (!silent)
 895                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 896                        sb->s_id);
 897         goto failed_mount;
 898 failed_mount3:
 899         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 900         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 901         percpu_counter_destroy(&sbi->s_dirs_counter);
 902 failed_mount2:
 903         for (i = 0; i < db_count; i++)
 904                 brelse(sbi->s_group_desc[i]);
 905 failed_mount_group_desc:
 906         kfree(sbi->s_group_desc);
 907         kfree(sbi->s_debts);
 908 failed_mount:
 909         brelse(bh);
 910 failed_sbi:
 911         sb->s_fs_info = NULL;
 912         kfree(sbi);
 913         return -EINVAL;
 914 }
 915
 916 static void ext2_commit_super (struct super_block * sb,
 917                                struct ext2_super_block * es)
 918 {
 919         es->s_wtime = cpu_to_le32(get_seconds());
 920         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 921         sb->s_dirt = 0;
 922 }
 923
 924 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 925 {
 926         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 927         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 928         es->s_wtime = cpu_to_le32(get_seconds());
 929         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 930         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 931         sb->s_dirt = 0;
 932 }
 933
 934 /*
 935  * In the second extended file system, it is not necessary to
 936  * write the super block since we use a mapping of the
 937  * disk super block in a buffer.
 938  *
 939  * However, this function is still used to set the fs valid
 940  * flags to 0.  We need to set this flag to 0 since the fs
 941  * may have been checked while mounted and e2fsck may have
 942  * set s_state to EXT2_VALID_FS after some corrections.
 943  */
 944
 945 void ext2_write_super (struct super_block * sb)
 946 {
 947         struct ext2_super_block * es;
 948         lock_kernel();
 949         if (!(sb->s_flags & MS_RDONLY)) {
 950                 es = EXT2_SB(sb)->s_es;
 951
 952                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
 953                         ext2_debug ("setting valid to 0\n");
 954                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
 955                                                   ~EXT2_VALID_FS);
 956                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 957                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 958                         es->s_mtime = cpu_to_le32(get_seconds());
 959                         ext2_sync_super(sb, es);
 960                 } else
 961                         ext2_commit_super (sb, es);
 962         }
 963         sb->s_dirt = 0;
 964         unlock_kernel();
 965 }
 966
 967 static int ext2_remount (struct super_block * sb, int * flags, char * data)
 968 {
 969         struct ext2_sb_info * sbi = EXT2_SB(sb);
 970         struct ext2_super_block * es;
 971         unsigned long old_mount_opt = sbi->s_mount_opt;
 972         struct ext2_mount_options old_opts;
 973         unsigned long old_sb_flags;
 974         int err;
 975
 976         /* Store the old options */
 977         old_sb_flags = sb->s_flags;
 978         old_opts.s_mount_opt = sbi->s_mount_opt;
 979         old_opts.s_resuid = sbi->s_resuid;
 980         old_opts.s_resgid = sbi->s_resgid;
 981
 982         /*
 983          * Allow the "check" option to be passed as a remount option.
 984          */
 985         if (!parse_options (data, sbi)) {
 986                 err = -EINVAL;
 987                 goto restore_opts;
 988         }
 989
 990         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 991                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
 992
 993         es = sbi->s_es;
 994         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
 995             (old_mount_opt & EXT2_MOUNT_XIP)) &&
 996             invalidate_inodes(sb))
 997                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
 998                              "xip remain in cache (no functional problem)");
 999         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1000                 return 0;
1001         if (*flags & MS_RDONLY) {
1002                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1003                     !(sbi->s_mount_state & EXT2_VALID_FS))
1004                         return 0;
1005                 /*
1006                  * OK, we are remounting a valid rw partition rdonly, so set
1007                  * the rdonly flag and then mark the partition as valid again.
1008                  */
1009                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1010                 es->s_mtime = cpu_to_le32(get_seconds());
1011         } else {
1012                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1013                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1014                 if (ret) {
1015                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1016                                "unsupported optional features (%x).\n",
1017                                sb->s_id, le32_to_cpu(ret));
1018                         err = -EROFS;
1019                         goto restore_opts;
1020                 }
1021                 /*
1022                  * Mounting a RDONLY partition read-write, so reread and
1023                  * store the current valid flag.  (It may have been changed
1024                  * by e2fsck since we originally mounted the partition.)
1025                  */
1026                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1027                 if (!ext2_setup_super (sb, es, 0))
1028                         sb->s_flags &= ~MS_RDONLY;
1029         }
1030         ext2_sync_super(sb, es);
1031         return 0;
1032 restore_opts:
1033         sbi->s_mount_opt = old_opts.s_mount_opt;
1034         sbi->s_resuid = old_opts.s_resuid;
1035         sbi->s_resgid = old_opts.s_resgid;
1036         sb->s_flags = old_sb_flags;
1037         return err;
1038 }
1039
1040 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1041 {
1042         struct super_block *sb = dentry->d_sb;
1043         struct ext2_sb_info *sbi = EXT2_SB(sb);
1044         unsigned long overhead;
1045         int i;
1046
1047         lock_super(sb);
1048         if (test_opt (sb, MINIX_DF))
1049                 overhead = 0;
1050         else {
1051                 /*
1052                  * Compute the overhead (FS structures)
1053                  */
1054
1055                 /*
1056                  * All of the blocks before first_data_block are
1057                  * overhead
1058                  */
1059                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1060
1061                 /*
1062                  * Add the overhead attributed to the superblock and
1063                  * block group descriptors.  If the sparse superblocks
1064                  * feature is turned on, then not all groups have this.
1065                  */
1066                 for (i = 0; i < sbi->s_groups_count; i++)
1067                         overhead += ext2_bg_has_super(sb, i) +
1068                                 ext2_bg_num_gdb(sb, i);
1069
1070                 /*
1071                  * Every block group has an inode bitmap, a block
1072                  * bitmap, and an inode table.
1073                  */
1074                 overhead += (sbi->s_groups_count *
1075                              (2 + sbi->s_itb_per_group));
1076         }
1077
1078         buf->f_type = EXT2_SUPER_MAGIC;
1079         buf->f_bsize = sb->s_blocksize;
1080         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1081         buf->f_bfree = ext2_count_free_blocks(sb);
1082         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1083         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1084                 buf->f_bavail = 0;
1085         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1086         buf->f_ffree = ext2_count_free_inodes (sb);
1087         buf->f_namelen = EXT2_NAME_LEN;
1088         unlock_super(sb);
1089         return 0;
1090 }
1091
1092 static int ext2_get_sb(struct file_system_type *fs_type,
1093         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1094 {
1095         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1096 }
1097
1098 #ifdef CONFIG_QUOTA
1099
1100 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1101  * acquiring the locks... As quota files are never truncated and quota code
1102  * itself serializes the operations (and noone else should touch the files)
1103  * we don't have to be afraid of races */
1104 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1105                                size_t len, loff_t off)
1106 {
1107         struct inode *inode = sb_dqopt(sb)->files[type];
1108         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1109         int err = 0;
1110         int offset = off & (sb->s_blocksize - 1);
1111         int tocopy;
1112         size_t toread;
1113         struct buffer_head tmp_bh;
1114         struct buffer_head *bh;
1115         loff_t i_size = i_size_read(inode);
1116
1117         if (off > i_size)
1118                 return 0;
1119         if (off+len > i_size)
1120                 len = i_size-off;
1121         toread = len;
1122         while (toread > 0) {
1123                 tocopy = sb->s_blocksize - offset < toread ?
1124                                 sb->s_blocksize - offset : toread;
1125
1126                 tmp_bh.b_state = 0;
1127                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1128                 if (err)
1129                         return err;
1130                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1131                         memset(data, 0, tocopy);
1132                 else {
1133                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1134                         if (!bh)
1135                                 return -EIO;
1136                         memcpy(data, bh->b_data+offset, tocopy);
1137                         brelse(bh);
1138                 }
1139                 offset = 0;
1140                 toread -= tocopy;
1141                 data += tocopy;
1142                 blk++;
1143         }
1144         return len;
1145 }
1146
1147 /* Write to quotafile */
1148 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1149                                 const char *data, size_t len, loff_t off)
1150 {
1151         struct inode *inode = sb_dqopt(sb)->files[type];
1152         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1153         int err = 0;
1154         int offset = off & (sb->s_blocksize - 1);
1155         int tocopy;
1156         size_t towrite = len;
1157         struct buffer_head tmp_bh;
1158         struct buffer_head *bh;
1159
1160         mutex_lock(&inode->i_mutex);
1161         while (towrite > 0) {
1162                 tocopy = sb->s_blocksize - offset < towrite ?
1163                                 sb->s_blocksize - offset : towrite;
1164
1165                 tmp_bh.b_state = 0;
1166                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1167                 if (err)
1168                         goto out;
1169                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1170                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1171                 else
1172                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1173                 if (!bh) {
1174                         err = -EIO;
1175                         goto out;
1176                 }
1177                 lock_buffer(bh);
1178                 memcpy(bh->b_data+offset, data, tocopy);
1179                 flush_dcache_page(bh->b_page);
1180                 set_buffer_uptodate(bh);
1181                 mark_buffer_dirty(bh);
1182                 unlock_buffer(bh);
1183                 brelse(bh);
1184                 offset = 0;
1185                 towrite -= tocopy;
1186                 data += tocopy;
1187                 blk++;
1188         }
1189 out:
1190         if (len == towrite)
1191                 return err;
1192         if (inode->i_size < off+len-towrite)
1193                 i_size_write(inode, off+len-towrite);
1194         inode->i_version++;
1195         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1196         mark_inode_dirty(inode);
1197         mutex_unlock(&inode->i_mutex);
1198         return len - towrite;
1199 }
1200
1201 #endif
1202
1203 static struct file_system_type ext2_fs_type = {
1204         .owner          = THIS_MODULE,
1205         .name           = "ext2",
1206         .get_sb         = ext2_get_sb,
1207         .kill_sb        = kill_block_super,
1208         .fs_flags       = FS_REQUIRES_DEV,
1209 };
1210
1211 static int __init init_ext2_fs(void)
1212 {
1213         int err = init_ext2_xattr();
1214         if (err)
1215                 return err;
1216         err = init_inodecache();
1217         if (err)
1218                 goto out1;
1219         err = register_filesystem(&ext2_fs_type);
1220         if (err)
1221                 goto out;
1222         return 0;
1223 out:
1224         destroy_inodecache();
1225 out1:
1226         exit_ext2_xattr();
1227         return err;
1228 }
1229
1230 static void __exit exit_ext2_fs(void)
1231 {
1232         unregister_filesystem(&ext2_fs_type);
1233         destroy_inodecache();
1234         exit_ext2_xattr();
1235 }
1236
1237 module_init(init_ext2_fs)
1238 module_exit(exit_ext2_fs)