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         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         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 368         int option;
 369
 370         if (!options)
 371                 return 1;
 372
 373         while ((p = strsep (&options, ",")) != NULL) {
 374                 int token;
 375                 if (!*p)
 376                         continue;
 377
 378                 token = match_token(p, tokens, args);
 379                 switch (token) {
 380                 case Opt_bsd_df:
 381                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 382                         break;
 383                 case Opt_minix_df:
 384                         set_opt (sbi->s_mount_opt, MINIX_DF);
 385                         break;
 386                 case Opt_grpid:
 387                         set_opt (sbi->s_mount_opt, GRPID);
 388                         break;
 389                 case Opt_nogrpid:
 390                         clear_opt (sbi->s_mount_opt, GRPID);
 391                         break;
 392                 case Opt_resuid:
 393                         if (match_int(&args[0], &option))
 394                                 return 0;
 395                         sbi->s_resuid = option;
 396                         break;
 397                 case Opt_resgid:
 398                         if (match_int(&args[0], &option))
 399                                 return 0;
 400                         sbi->s_resgid = option;
 401                         break;
 402                 case Opt_sb:
 403                         /* handled by get_sb_block() instead of here */
 404                         /* *sb_block = match_int(&args[0]); */
 405                         break;
 406                 case Opt_err_panic:
 407                         kind = EXT2_MOUNT_ERRORS_PANIC;
 408                         break;
 409                 case Opt_err_ro:
 410                         kind = EXT2_MOUNT_ERRORS_RO;
 411                         break;
 412                 case Opt_err_cont:
 413                         kind = EXT2_MOUNT_ERRORS_CONT;
 414                         break;
 415                 case Opt_nouid32:
 416                         set_opt (sbi->s_mount_opt, NO_UID32);
 417                         break;
 418                 case Opt_nocheck:
 419                         clear_opt (sbi->s_mount_opt, CHECK);
 420                         break;
 421                 case Opt_debug:
 422                         set_opt (sbi->s_mount_opt, DEBUG);
 423                         break;
 424                 case Opt_oldalloc:
 425                         set_opt (sbi->s_mount_opt, OLDALLOC);
 426                         break;
 427                 case Opt_orlov:
 428                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 429                         break;
 430                 case Opt_nobh:
 431                         set_opt (sbi->s_mount_opt, NOBH);
 432                         break;
 433 #ifdef CONFIG_EXT2_FS_XATTR
 434                 case Opt_user_xattr:
 435                         set_opt (sbi->s_mount_opt, XATTR_USER);
 436                         break;
 437                 case Opt_nouser_xattr:
 438                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 439                         break;
 440 #else
 441                 case Opt_user_xattr:
 442                 case Opt_nouser_xattr:
 443                         printk("EXT2 (no)user_xattr options not supported\n");
 444                         break;
 445 #endif
 446 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 447                 case Opt_acl:
 448                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 449                         break;
 450                 case Opt_noacl:
 451                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 452                         break;
 453 #else
 454                 case Opt_acl:
 455                 case Opt_noacl:
 456                         printk("EXT2 (no)acl options not supported\n");
 457                         break;
 458 #endif
 459                 case Opt_xip:
 460 #ifdef CONFIG_EXT2_FS_XIP
 461                         set_opt (sbi->s_mount_opt, XIP);
 462 #else
 463                         printk("EXT2 xip option not supported\n");
 464 #endif
 465                         break;
 466
 467 #if defined(CONFIG_QUOTA)
 468                 case Opt_quota:
 469                 case Opt_usrquota:
 470                         set_opt(sbi->s_mount_opt, USRQUOTA);
 471                         break;
 472
 473                 case Opt_grpquota:
 474                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 475                         break;
 476 #else
 477                 case Opt_quota:
 478                 case Opt_usrquota:
 479                 case Opt_grpquota:
 480                         printk(KERN_ERR
 481                                 "EXT2-fs: quota operations not supported.\n");
 482
 483                         break;
 484 #endif
 485
 486                 case Opt_ignore:
 487                         break;
 488                 default:
 489                         return 0;
 490                 }
 491         }
 492         sbi->s_mount_opt |= kind;
 493         return 1;
 494 }
 495
 496 static int ext2_setup_super (struct super_block * sb,
 497                               struct ext2_super_block * es,
 498                               int read_only)
 499 {
 500         int res = 0;
 501         struct ext2_sb_info *sbi = EXT2_SB(sb);
 502
 503         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 504                 printk ("EXT2-fs warning: revision level too high, "
 505                         "forcing read-only mode\n");
 506                 res = MS_RDONLY;
 507         }
 508         if (read_only)
 509                 return res;
 510         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 511                 printk ("EXT2-fs warning: mounting unchecked fs, "
 512                         "running e2fsck is recommended\n");
 513         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 514                 printk ("EXT2-fs warning: mounting fs with errors, "
 515                         "running e2fsck is recommended\n");
 516         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 517                  le16_to_cpu(es->s_mnt_count) >=
 518                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 519                 printk ("EXT2-fs warning: maximal mount count reached, "
 520                         "running e2fsck is recommended\n");
 521         else if (le32_to_cpu(es->s_checkinterval) &&
 522                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 523                 printk ("EXT2-fs warning: checktime reached, "
 524                         "running e2fsck is recommended\n");
 525         if (!le16_to_cpu(es->s_max_mnt_count))
 526                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 527         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 528         ext2_write_super(sb);
 529         if (test_opt (sb, DEBUG))
 530                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 531                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 532                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 533                         sbi->s_frag_size,
 534                         sbi->s_groups_count,
 535                         EXT2_BLOCKS_PER_GROUP(sb),
 536                         EXT2_INODES_PER_GROUP(sb),
 537                         sbi->s_mount_opt);
 538         return res;
 539 }
 540
 541 static int ext2_check_descriptors (struct super_block * sb)
 542 {
 543         int i;
 544         int desc_block = 0;
 545         struct ext2_sb_info *sbi = EXT2_SB(sb);
 546         unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 547         unsigned long last_block;
 548         struct ext2_group_desc * gdp = NULL;
 549
 550         ext2_debug ("Checking group descriptors");
 551
 552         for (i = 0; i < sbi->s_groups_count; i++)
 553         {
 554                 if (i == sbi->s_groups_count - 1)
 555                         last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
 556                 else
 557                         last_block = first_block +
 558                                 (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 559
 560                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 561                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 562                 if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
 563                     le32_to_cpu(gdp->bg_block_bitmap) > last_block)
 564                 {
 565                         ext2_error (sb, "ext2_check_descriptors",
 566                                     "Block bitmap for group %d"
 567                                     " not in group (block %lu)!",
 568                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 569                         return 0;
 570                 }
 571                 if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
 572                     le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
 573                 {
 574                         ext2_error (sb, "ext2_check_descriptors",
 575                                     "Inode bitmap for group %d"
 576                                     " not in group (block %lu)!",
 577                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 578                         return 0;
 579                 }
 580                 if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
 581                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
 582                     last_block)
 583                 {
 584                         ext2_error (sb, "ext2_check_descriptors",
 585                                     "Inode table for group %d"
 586                                     " not in group (block %lu)!",
 587                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 588                         return 0;
 589                 }
 590                 first_block += EXT2_BLOCKS_PER_GROUP(sb);
 591                 gdp++;
 592         }
 593         return 1;
 594 }
 595
 596 #define log2(n) ffz(~(n))
 597
 598 /*
 599  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 600  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 601  * We need to be 1 filesystem block less than the 2^32 sector limit.
 602  */
 603 static loff_t ext2_max_size(int bits)
 604 {
 605         loff_t res = EXT2_NDIR_BLOCKS;
 606         /* This constant is calculated to be the largest file size for a
 607          * dense, 4k-blocksize file such that the total number of
 608          * sectors in the file, including data and all indirect blocks,
 609          * does not exceed 2^32. */
 610         const loff_t upper_limit = 0x1ff7fffd000LL;
 611
 612         res += 1LL << (bits-2);
 613         res += 1LL << (2*(bits-2));
 614         res += 1LL << (3*(bits-2));
 615         res <<= bits;
 616         if (res > upper_limit)
 617                 res = upper_limit;
 618         return res;
 619 }
 620
 621 static unsigned long descriptor_loc(struct super_block *sb,
 622                                     unsigned long logic_sb_block,
 623                                     int nr)
 624 {
 625         struct ext2_sb_info *sbi = EXT2_SB(sb);
 626         unsigned long bg, first_data_block, first_meta_bg;
 627         int has_super = 0;
 628
 629         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 630         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 631
 632         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 633             nr < first_meta_bg)
 634                 return (logic_sb_block + nr + 1);
 635         bg = sbi->s_desc_per_block * nr;
 636         if (ext2_bg_has_super(sb, bg))
 637                 has_super = 1;
 638         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 639 }
 640
 641 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 642 {
 643         struct buffer_head * bh;
 644         struct ext2_sb_info * sbi;
 645         struct ext2_super_block * es;
 646         struct inode *root;
 647         unsigned long block;
 648         unsigned long sb_block = get_sb_block(&data);
 649         unsigned long logic_sb_block;
 650         unsigned long offset = 0;
 651         unsigned long def_mount_opts;
 652         int blocksize = BLOCK_SIZE;
 653         int db_count;
 654         int i, j;
 655         __le32 features;
 656
 657         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 658         if (!sbi)
 659                 return -ENOMEM;
 660         sb->s_fs_info = sbi;
 661
 662         /*
 663          * See what the current blocksize for the device is, and
 664          * use that as the blocksize.  Otherwise (or if the blocksize
 665          * is smaller than the default) use the default.
 666          * This is important for devices that have a hardware
 667          * sectorsize that is larger than the default.
 668          */
 669         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 670         if (!blocksize) {
 671                 printk ("EXT2-fs: unable to set blocksize\n");
 672                 goto failed_sbi;
 673         }
 674
 675         /*
 676          * If the superblock doesn't start on a hardware sector boundary,
 677          * calculate the offset.
 678          */
 679         if (blocksize != BLOCK_SIZE) {
 680                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 681                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 682         } else {
 683                 logic_sb_block = sb_block;
 684         }
 685
 686         if (!(bh = sb_bread(sb, logic_sb_block))) {
 687                 printk ("EXT2-fs: unable to read superblock\n");
 688                 goto failed_sbi;
 689         }
 690         /*
 691          * Note: s_es must be initialized as soon as possible because
 692          *       some ext2 macro-instructions depend on its value
 693          */
 694         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 695         sbi->s_es = es;
 696         sb->s_magic = le16_to_cpu(es->s_magic);
 697
 698         if (sb->s_magic != EXT2_SUPER_MAGIC)
 699                 goto cantfind_ext2;
 700
 701         /* Set defaults before we parse the mount options */
 702         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 703         if (def_mount_opts & EXT2_DEFM_DEBUG)
 704                 set_opt(sbi->s_mount_opt, DEBUG);
 705         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 706                 set_opt(sbi->s_mount_opt, GRPID);
 707         if (def_mount_opts & EXT2_DEFM_UID16)
 708                 set_opt(sbi->s_mount_opt, NO_UID32);
 709         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 710                 set_opt(sbi->s_mount_opt, XATTR_USER);
 711         if (def_mount_opts & EXT2_DEFM_ACL)
 712                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 713
 714         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 715                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 716         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 717                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 718
 719         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 720         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 721
 722         if (!parse_options ((char *) data, sbi))
 723                 goto failed_mount;
 724
 725         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 726                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 727                  MS_POSIXACL : 0);
 728
 729         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 730                                     EXT2_MOUNT_XIP if not */
 731
 732         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 733             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 734              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 735              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 736                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 737                        "running e2fsck is recommended\n");
 738         /*
 739          * Check feature flags regardless of the revision level, since we
 740          * previously didn't change the revision level when setting the flags,
 741          * so there is a chance incompat flags are set on a rev 0 filesystem.
 742          */
 743         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 744         if (features) {
 745                 printk("EXT2-fs: %s: couldn't mount because of "
 746                        "unsupported optional features (%x).\n",
 747                        sb->s_id, le32_to_cpu(features));
 748                 goto failed_mount;
 749         }
 750         if (!(sb->s_flags & MS_RDONLY) &&
 751             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 752                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 753                        "unsupported optional features (%x).\n",
 754                        sb->s_id, le32_to_cpu(features));
 755                 goto failed_mount;
 756         }
 757
 758         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 759
 760         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 761                                   (sb->s_blocksize != blocksize))) {
 762                 if (!silent)
 763                         printk("XIP: Unsupported blocksize\n");
 764                 goto failed_mount;
 765         }
 766
 767         /* If the blocksize doesn't match, re-read the thing.. */
 768         if (sb->s_blocksize != blocksize) {
 769                 brelse(bh);
 770
 771                 if (!sb_set_blocksize(sb, blocksize)) {
 772                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 773                         goto failed_sbi;
 774                 }
 775
 776                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 777                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 778                 bh = sb_bread(sb, logic_sb_block);
 779                 if(!bh) {
 780                         printk("EXT2-fs: Couldn't read superblock on "
 781                                "2nd try.\n");
 782                         goto failed_sbi;
 783                 }
 784                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 785                 sbi->s_es = es;
 786                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 787                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 788                         goto failed_mount;
 789                 }
 790         }
 791
 792         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 793
 794         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 795                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 796                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 797         } else {
 798                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 799                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 800                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 801                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 802                     (sbi->s_inode_size > blocksize)) {
 803                         printk ("EXT2-fs: unsupported inode size: %d\n",
 804                                 sbi->s_inode_size);
 805                         goto failed_mount;
 806                 }
 807         }
 808
 809         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 810                                    le32_to_cpu(es->s_log_frag_size);
 811         if (sbi->s_frag_size == 0)
 812                 goto cantfind_ext2;
 813         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 814
 815         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 816         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 817         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 818
 819         if (EXT2_INODE_SIZE(sb) == 0)
 820                 goto cantfind_ext2;
 821         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 822         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
 823                 goto cantfind_ext2;
 824         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 825                                         sbi->s_inodes_per_block;
 826         sbi->s_desc_per_block = sb->s_blocksize /
 827                                         sizeof (struct ext2_group_desc);
 828         sbi->s_sbh = bh;
 829         sbi->s_mount_state = le16_to_cpu(es->s_state);
 830         sbi->s_addr_per_block_bits =
 831                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 832         sbi->s_desc_per_block_bits =
 833                 log2 (EXT2_DESC_PER_BLOCK(sb));
 834
 835         if (sb->s_magic != EXT2_SUPER_MAGIC)
 836                 goto cantfind_ext2;
 837
 838         if (sb->s_blocksize != bh->b_size) {
 839                 if (!silent)
 840                         printk ("VFS: Unsupported blocksize on dev "
 841                                 "%s.\n", sb->s_id);
 842                 goto failed_mount;
 843         }
 844
 845         if (sb->s_blocksize != sbi->s_frag_size) {
 846                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 847                         sbi->s_frag_size, sb->s_blocksize);
 848                 goto failed_mount;
 849         }
 850
 851         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 852                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 853                         sbi->s_blocks_per_group);
 854                 goto failed_mount;
 855         }
 856         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 857                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 858                         sbi->s_frags_per_group);
 859                 goto failed_mount;
 860         }
 861         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 862                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 863                         sbi->s_inodes_per_group);
 864                 goto failed_mount;
 865         }
 866
 867         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 868                 goto cantfind_ext2;
 869         sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
 870                                 le32_to_cpu(es->s_first_data_block) - 1)
 871                                         / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
 872         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 873                    EXT2_DESC_PER_BLOCK(sb);
 874         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 875         if (sbi->s_group_desc == NULL) {
 876                 printk ("EXT2-fs: not enough memory\n");
 877                 goto failed_mount;
 878         }
 879         bgl_lock_init(&sbi->s_blockgroup_lock);
 880         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 881                                GFP_KERNEL);
 882         if (!sbi->s_debts) {
 883                 printk ("EXT2-fs: not enough memory\n");
 884                 goto failed_mount_group_desc;
 885         }
 886         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 887         for (i = 0; i < db_count; i++) {
 888                 block = descriptor_loc(sb, logic_sb_block, i);
 889                 sbi->s_group_desc[i] = sb_bread(sb, block);
 890                 if (!sbi->s_group_desc[i]) {
 891                         for (j = 0; j < i; j++)
 892                                 brelse (sbi->s_group_desc[j]);
 893                         printk ("EXT2-fs: unable to read group descriptors\n");
 894                         goto failed_mount_group_desc;
 895                 }
 896         }
 897         if (!ext2_check_descriptors (sb)) {
 898                 printk ("EXT2-fs: group descriptors corrupted!\n");
 899                 goto failed_mount2;
 900         }
 901         sbi->s_gdb_count = db_count;
 902         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 903         spin_lock_init(&sbi->s_next_gen_lock);
 904
 905         percpu_counter_init(&sbi->s_freeblocks_counter,
 906                                 ext2_count_free_blocks(sb));
 907         percpu_counter_init(&sbi->s_freeinodes_counter,
 908                                 ext2_count_free_inodes(sb));
 909         percpu_counter_init(&sbi->s_dirs_counter,
 910                                 ext2_count_dirs(sb));
 911         /*
 912          * set up enough so that it can read an inode
 913          */
 914         sb->s_op = &ext2_sops;
 915         sb->s_export_op = &ext2_export_ops;
 916         sb->s_xattr = ext2_xattr_handlers;
 917         root = iget(sb, EXT2_ROOT_INO);
 918         sb->s_root = d_alloc_root(root);
 919         if (!sb->s_root) {
 920                 iput(root);
 921                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 922                 goto failed_mount3;
 923         }
 924         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 925                 dput(sb->s_root);
 926                 sb->s_root = NULL;
 927                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 928                 goto failed_mount3;
 929         }
 930         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 931                 ext2_warning(sb, __FUNCTION__,
 932                         "mounting ext3 filesystem as ext2");
 933         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 934         return 0;
 935
 936 cantfind_ext2:
 937         if (!silent)
 938                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 939                        sb->s_id);
 940         goto failed_mount;
 941 failed_mount3:
 942         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 943         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 944         percpu_counter_destroy(&sbi->s_dirs_counter);
 945 failed_mount2:
 946         for (i = 0; i < db_count; i++)
 947                 brelse(sbi->s_group_desc[i]);
 948 failed_mount_group_desc:
 949         kfree(sbi->s_group_desc);
 950         kfree(sbi->s_debts);
 951 failed_mount:
 952         brelse(bh);
 953 failed_sbi:
 954         sb->s_fs_info = NULL;
 955         kfree(sbi);
 956         return -EINVAL;
 957 }
 958
 959 static void ext2_commit_super (struct super_block * sb,
 960                                struct ext2_super_block * es)
 961 {
 962         es->s_wtime = cpu_to_le32(get_seconds());
 963         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 964         sb->s_dirt = 0;
 965 }
 966
 967 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 968 {
 969         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 970         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 971         es->s_wtime = cpu_to_le32(get_seconds());
 972         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 973         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 974         sb->s_dirt = 0;
 975 }
 976
 977 /*
 978  * In the second extended file system, it is not necessary to
 979  * write the super block since we use a mapping of the
 980  * disk super block in a buffer.
 981  *
 982  * However, this function is still used to set the fs valid
 983  * flags to 0.  We need to set this flag to 0 since the fs
 984  * may have been checked while mounted and e2fsck may have
 985  * set s_state to EXT2_VALID_FS after some corrections.
 986  */
 987
 988 void ext2_write_super (struct super_block * sb)
 989 {
 990         struct ext2_super_block * es;
 991         lock_kernel();
 992         if (!(sb->s_flags & MS_RDONLY)) {
 993                 es = EXT2_SB(sb)->s_es;
 994
 995                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
 996                         ext2_debug ("setting valid to 0\n");
 997                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
 998                                                   ~EXT2_VALID_FS);
 999                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1000                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1001                         es->s_mtime = cpu_to_le32(get_seconds());
1002                         ext2_sync_super(sb, es);
1003                 } else
1004                         ext2_commit_super (sb, es);
1005         }
1006         sb->s_dirt = 0;
1007         unlock_kernel();
1008 }
1009
1010 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1011 {
1012         struct ext2_sb_info * sbi = EXT2_SB(sb);
1013         struct ext2_super_block * es;
1014         unsigned long old_mount_opt = sbi->s_mount_opt;
1015         struct ext2_mount_options old_opts;
1016         unsigned long old_sb_flags;
1017         int err;
1018
1019         /* Store the old options */
1020         old_sb_flags = sb->s_flags;
1021         old_opts.s_mount_opt = sbi->s_mount_opt;
1022         old_opts.s_resuid = sbi->s_resuid;
1023         old_opts.s_resgid = sbi->s_resgid;
1024
1025         /*
1026          * Allow the "check" option to be passed as a remount option.
1027          */
1028         if (!parse_options (data, sbi)) {
1029                 err = -EINVAL;
1030                 goto restore_opts;
1031         }
1032
1033         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1034                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1035
1036         es = sbi->s_es;
1037         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1038             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1039             invalidate_inodes(sb))
1040                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1041                              "xip remain in cache (no functional problem)");
1042         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1043                 return 0;
1044         if (*flags & MS_RDONLY) {
1045                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1046                     !(sbi->s_mount_state & EXT2_VALID_FS))
1047                         return 0;
1048                 /*
1049                  * OK, we are remounting a valid rw partition rdonly, so set
1050                  * the rdonly flag and then mark the partition as valid again.
1051                  */
1052                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1053                 es->s_mtime = cpu_to_le32(get_seconds());
1054         } else {
1055                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1056                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1057                 if (ret) {
1058                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1059                                "unsupported optional features (%x).\n",
1060                                sb->s_id, le32_to_cpu(ret));
1061                         err = -EROFS;
1062                         goto restore_opts;
1063                 }
1064                 /*
1065                  * Mounting a RDONLY partition read-write, so reread and
1066                  * store the current valid flag.  (It may have been changed
1067                  * by e2fsck since we originally mounted the partition.)
1068                  */
1069                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1070                 if (!ext2_setup_super (sb, es, 0))
1071                         sb->s_flags &= ~MS_RDONLY;
1072         }
1073         ext2_sync_super(sb, es);
1074         return 0;
1075 restore_opts:
1076         sbi->s_mount_opt = old_opts.s_mount_opt;
1077         sbi->s_resuid = old_opts.s_resuid;
1078         sbi->s_resgid = old_opts.s_resgid;
1079         sb->s_flags = old_sb_flags;
1080         return err;
1081 }
1082
1083 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1084 {
1085         struct super_block *sb = dentry->d_sb;
1086         struct ext2_sb_info *sbi = EXT2_SB(sb);
1087         unsigned long overhead;
1088         int i;
1089
1090         if (test_opt (sb, MINIX_DF))
1091                 overhead = 0;
1092         else {
1093                 /*
1094                  * Compute the overhead (FS structures)
1095                  */
1096
1097                 /*
1098                  * All of the blocks before first_data_block are
1099                  * overhead
1100                  */
1101                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1102
1103                 /*
1104                  * Add the overhead attributed to the superblock and
1105                  * block group descriptors.  If the sparse superblocks
1106                  * feature is turned on, then not all groups have this.
1107                  */
1108                 for (i = 0; i < sbi->s_groups_count; i++)
1109                         overhead += ext2_bg_has_super(sb, i) +
1110                                 ext2_bg_num_gdb(sb, i);
1111
1112                 /*
1113                  * Every block group has an inode bitmap, a block
1114                  * bitmap, and an inode table.
1115                  */
1116                 overhead += (sbi->s_groups_count *
1117                              (2 + sbi->s_itb_per_group));
1118         }
1119
1120         buf->f_type = EXT2_SUPER_MAGIC;
1121         buf->f_bsize = sb->s_blocksize;
1122         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1123         buf->f_bfree = ext2_count_free_blocks(sb);
1124         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1125         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1126                 buf->f_bavail = 0;
1127         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1128         buf->f_ffree = ext2_count_free_inodes (sb);
1129         buf->f_namelen = EXT2_NAME_LEN;
1130         return 0;
1131 }
1132
1133 static int ext2_get_sb(struct file_system_type *fs_type,
1134         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1135 {
1136         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1137 }
1138
1139 #ifdef CONFIG_QUOTA
1140
1141 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1142  * acquiring the locks... As quota files are never truncated and quota code
1143  * itself serializes the operations (and noone else should touch the files)
1144  * we don't have to be afraid of races */
1145 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1146                                size_t len, loff_t off)
1147 {
1148         struct inode *inode = sb_dqopt(sb)->files[type];
1149         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1150         int err = 0;
1151         int offset = off & (sb->s_blocksize - 1);
1152         int tocopy;
1153         size_t toread;
1154         struct buffer_head tmp_bh;
1155         struct buffer_head *bh;
1156         loff_t i_size = i_size_read(inode);
1157
1158         if (off > i_size)
1159                 return 0;
1160         if (off+len > i_size)
1161                 len = i_size-off;
1162         toread = len;
1163         while (toread > 0) {
1164                 tocopy = sb->s_blocksize - offset < toread ?
1165                                 sb->s_blocksize - offset : toread;
1166
1167                 tmp_bh.b_state = 0;
1168                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1169                 if (err)
1170                         return err;
1171                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1172                         memset(data, 0, tocopy);
1173                 else {
1174                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1175                         if (!bh)
1176                                 return -EIO;
1177                         memcpy(data, bh->b_data+offset, tocopy);
1178                         brelse(bh);
1179                 }
1180                 offset = 0;
1181                 toread -= tocopy;
1182                 data += tocopy;
1183                 blk++;
1184         }
1185         return len;
1186 }
1187
1188 /* Write to quotafile */
1189 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1190                                 const char *data, size_t len, loff_t off)
1191 {
1192         struct inode *inode = sb_dqopt(sb)->files[type];
1193         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1194         int err = 0;
1195         int offset = off & (sb->s_blocksize - 1);
1196         int tocopy;
1197         size_t towrite = len;
1198         struct buffer_head tmp_bh;
1199         struct buffer_head *bh;
1200
1201         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1202         while (towrite > 0) {
1203                 tocopy = sb->s_blocksize - offset < towrite ?
1204                                 sb->s_blocksize - offset : towrite;
1205
1206                 tmp_bh.b_state = 0;
1207                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1208                 if (err)
1209                         goto out;
1210                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1211                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1212                 else
1213                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1214                 if (!bh) {
1215                         err = -EIO;
1216                         goto out;
1217                 }
1218                 lock_buffer(bh);
1219                 memcpy(bh->b_data+offset, data, tocopy);
1220                 flush_dcache_page(bh->b_page);
1221                 set_buffer_uptodate(bh);
1222                 mark_buffer_dirty(bh);
1223                 unlock_buffer(bh);
1224                 brelse(bh);
1225                 offset = 0;
1226                 towrite -= tocopy;
1227                 data += tocopy;
1228                 blk++;
1229         }
1230 out:
1231         if (len == towrite)
1232                 return err;
1233         if (inode->i_size < off+len-towrite)
1234                 i_size_write(inode, off+len-towrite);
1235         inode->i_version++;
1236         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1237         mark_inode_dirty(inode);
1238         mutex_unlock(&inode->i_mutex);
1239         return len - towrite;
1240 }
1241
1242 #endif
1243
1244 static struct file_system_type ext2_fs_type = {
1245         .owner          = THIS_MODULE,
1246         .name           = "ext2",
1247         .get_sb         = ext2_get_sb,
1248         .kill_sb        = kill_block_super,
1249         .fs_flags       = FS_REQUIRES_DEV,
1250 };
1251
1252 static int __init init_ext2_fs(void)
1253 {
1254         int err = init_ext2_xattr();
1255         if (err)
1256                 return err;
1257         err = init_inodecache();
1258         if (err)
1259                 goto out1;
1260         err = register_filesystem(&ext2_fs_type);
1261         if (err)
1262                 goto out;
1263         return 0;
1264 out:
1265         destroy_inodecache();
1266 out1:
1267         exit_ext2_xattr();
1268         return err;
1269 }
1270
1271 static void __exit exit_ext2_fs(void)
1272 {
1273         unregister_filesystem(&ext2_fs_type);
1274         destroy_inodecache();
1275         exit_ext2_xattr();
1276 }
1277
1278 module_init(init_ext2_fs)
1279 module_exit(exit_ext2_fs)