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 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
 255 {
 256         __u32 *objp = vobjp;
 257         unsigned long ino = objp[0];
 258         __u32 generation = objp[1];
 259         struct inode *inode;
 260         struct dentry *result;
 261
 262         if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
 263                 return ERR_PTR(-ESTALE);
 264         if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
 265                 return ERR_PTR(-ESTALE);
 266
 267         /* iget isn't really right if the inode is currently unallocated!!
 268          * ext2_read_inode currently does appropriate checks, but
 269          * it might be "neater" to call ext2_get_inode first and check
 270          * if the inode is valid.....
 271          */
 272         inode = iget(sb, ino);
 273         if (inode == NULL)
 274                 return ERR_PTR(-ENOMEM);
 275         if (is_bad_inode(inode) ||
 276             (generation && inode->i_generation != generation)) {
 277                 /* we didn't find the right inode.. */
 278                 iput(inode);
 279                 return ERR_PTR(-ESTALE);
 280         }
 281         /* now to find a dentry.
 282          * If possible, get a well-connected one
 283          */
 284         result = d_alloc_anon(inode);
 285         if (!result) {
 286                 iput(inode);
 287                 return ERR_PTR(-ENOMEM);
 288         }
 289         return result;
 290 }
 291
 292 /* Yes, most of these are left as NULL!!
 293  * A NULL value implies the default, which works with ext2-like file
 294  * systems, but can be improved upon.
 295  * Currently only get_parent is required.
 296  */
 297 static struct export_operations ext2_export_ops = {
 298         .get_parent = ext2_get_parent,
 299         .get_dentry = ext2_get_dentry,
 300 };
 301
 302 static unsigned long get_sb_block(void **data)
 303 {
 304         unsigned long   sb_block;
 305         char            *options = (char *) *data;
 306
 307         if (!options || strncmp(options, "sb=", 3) != 0)
 308                 return 1;       /* Default location */
 309         options += 3;
 310         sb_block = simple_strtoul(options, &options, 0);
 311         if (*options && *options != ',') {
 312                 printk("EXT2-fs: Invalid sb specification: %s\n",
 313                        (char *) *data);
 314                 return 1;
 315         }
 316         if (*options == ',')
 317                 options++;
 318         *data = (void *) options;
 319         return sb_block;
 320 }
 321
 322 enum {
 323         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 324         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
 325         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
 326         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
 327         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
 328         Opt_usrquota, Opt_grpquota
 329 };
 330
 331 static match_table_t tokens = {
 332         {Opt_bsd_df, "bsddf"},
 333         {Opt_minix_df, "minixdf"},
 334         {Opt_grpid, "grpid"},
 335         {Opt_grpid, "bsdgroups"},
 336         {Opt_nogrpid, "nogrpid"},
 337         {Opt_nogrpid, "sysvgroups"},
 338         {Opt_resgid, "resgid=%u"},
 339         {Opt_resuid, "resuid=%u"},
 340         {Opt_sb, "sb=%u"},
 341         {Opt_err_cont, "errors=continue"},
 342         {Opt_err_panic, "errors=panic"},
 343         {Opt_err_ro, "errors=remount-ro"},
 344         {Opt_nouid32, "nouid32"},
 345         {Opt_nocheck, "check=none"},
 346         {Opt_nocheck, "nocheck"},
 347         {Opt_debug, "debug"},
 348         {Opt_oldalloc, "oldalloc"},
 349         {Opt_orlov, "orlov"},
 350         {Opt_nobh, "nobh"},
 351         {Opt_user_xattr, "user_xattr"},
 352         {Opt_nouser_xattr, "nouser_xattr"},
 353         {Opt_acl, "acl"},
 354         {Opt_noacl, "noacl"},
 355         {Opt_xip, "xip"},
 356         {Opt_grpquota, "grpquota"},
 357         {Opt_ignore, "noquota"},
 358         {Opt_quota, "quota"},
 359         {Opt_usrquota, "usrquota"},
 360         {Opt_err, NULL}
 361 };
 362
 363 static int parse_options (char * options,
 364                           struct ext2_sb_info *sbi)
 365 {
 366         char * p;
 367         substring_t args[MAX_OPT_ARGS];
 368         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 369         int option;
 370
 371         if (!options)
 372                 return 1;
 373
 374         while ((p = strsep (&options, ",")) != NULL) {
 375                 int token;
 376                 if (!*p)
 377                         continue;
 378
 379                 token = match_token(p, tokens, args);
 380                 switch (token) {
 381                 case Opt_bsd_df:
 382                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 383                         break;
 384                 case Opt_minix_df:
 385                         set_opt (sbi->s_mount_opt, MINIX_DF);
 386                         break;
 387                 case Opt_grpid:
 388                         set_opt (sbi->s_mount_opt, GRPID);
 389                         break;
 390                 case Opt_nogrpid:
 391                         clear_opt (sbi->s_mount_opt, GRPID);
 392                         break;
 393                 case Opt_resuid:
 394                         if (match_int(&args[0], &option))
 395                                 return 0;
 396                         sbi->s_resuid = option;
 397                         break;
 398                 case Opt_resgid:
 399                         if (match_int(&args[0], &option))
 400                                 return 0;
 401                         sbi->s_resgid = option;
 402                         break;
 403                 case Opt_sb:
 404                         /* handled by get_sb_block() instead of here */
 405                         /* *sb_block = match_int(&args[0]); */
 406                         break;
 407                 case Opt_err_panic:
 408                         kind = EXT2_MOUNT_ERRORS_PANIC;
 409                         break;
 410                 case Opt_err_ro:
 411                         kind = EXT2_MOUNT_ERRORS_RO;
 412                         break;
 413                 case Opt_err_cont:
 414                         kind = EXT2_MOUNT_ERRORS_CONT;
 415                         break;
 416                 case Opt_nouid32:
 417                         set_opt (sbi->s_mount_opt, NO_UID32);
 418                         break;
 419                 case Opt_nocheck:
 420                         clear_opt (sbi->s_mount_opt, CHECK);
 421                         break;
 422                 case Opt_debug:
 423                         set_opt (sbi->s_mount_opt, DEBUG);
 424                         break;
 425                 case Opt_oldalloc:
 426                         set_opt (sbi->s_mount_opt, OLDALLOC);
 427                         break;
 428                 case Opt_orlov:
 429                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 430                         break;
 431                 case Opt_nobh:
 432                         set_opt (sbi->s_mount_opt, NOBH);
 433                         break;
 434 #ifdef CONFIG_EXT2_FS_XATTR
 435                 case Opt_user_xattr:
 436                         set_opt (sbi->s_mount_opt, XATTR_USER);
 437                         break;
 438                 case Opt_nouser_xattr:
 439                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 440                         break;
 441 #else
 442                 case Opt_user_xattr:
 443                 case Opt_nouser_xattr:
 444                         printk("EXT2 (no)user_xattr options not supported\n");
 445                         break;
 446 #endif
 447 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 448                 case Opt_acl:
 449                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 450                         break;
 451                 case Opt_noacl:
 452                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 453                         break;
 454 #else
 455                 case Opt_acl:
 456                 case Opt_noacl:
 457                         printk("EXT2 (no)acl options not supported\n");
 458                         break;
 459 #endif
 460                 case Opt_xip:
 461 #ifdef CONFIG_EXT2_FS_XIP
 462                         set_opt (sbi->s_mount_opt, XIP);
 463 #else
 464                         printk("EXT2 xip option not supported\n");
 465 #endif
 466                         break;
 467
 468 #if defined(CONFIG_QUOTA)
 469                 case Opt_quota:
 470                 case Opt_usrquota:
 471                         set_opt(sbi->s_mount_opt, USRQUOTA);
 472                         break;
 473
 474                 case Opt_grpquota:
 475                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 476                         break;
 477 #else
 478                 case Opt_quota:
 479                 case Opt_usrquota:
 480                 case Opt_grpquota:
 481                         printk(KERN_ERR
 482                                 "EXT2-fs: quota operations not supported.\n");
 483
 484                         break;
 485 #endif
 486
 487                 case Opt_ignore:
 488                         break;
 489                 default:
 490                         return 0;
 491                 }
 492         }
 493         sbi->s_mount_opt |= kind;
 494         return 1;
 495 }
 496
 497 static int ext2_setup_super (struct super_block * sb,
 498                               struct ext2_super_block * es,
 499                               int read_only)
 500 {
 501         int res = 0;
 502         struct ext2_sb_info *sbi = EXT2_SB(sb);
 503
 504         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 505                 printk ("EXT2-fs warning: revision level too high, "
 506                         "forcing read-only mode\n");
 507                 res = MS_RDONLY;
 508         }
 509         if (read_only)
 510                 return res;
 511         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 512                 printk ("EXT2-fs warning: mounting unchecked fs, "
 513                         "running e2fsck is recommended\n");
 514         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 515                 printk ("EXT2-fs warning: mounting fs with errors, "
 516                         "running e2fsck is recommended\n");
 517         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 518                  le16_to_cpu(es->s_mnt_count) >=
 519                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 520                 printk ("EXT2-fs warning: maximal mount count reached, "
 521                         "running e2fsck is recommended\n");
 522         else if (le32_to_cpu(es->s_checkinterval) &&
 523                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 524                 printk ("EXT2-fs warning: checktime reached, "
 525                         "running e2fsck is recommended\n");
 526         if (!le16_to_cpu(es->s_max_mnt_count))
 527                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 528         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 529         ext2_write_super(sb);
 530         if (test_opt (sb, DEBUG))
 531                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 532                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 533                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 534                         sbi->s_frag_size,
 535                         sbi->s_groups_count,
 536                         EXT2_BLOCKS_PER_GROUP(sb),
 537                         EXT2_INODES_PER_GROUP(sb),
 538                         sbi->s_mount_opt);
 539         return res;
 540 }
 541
 542 static int ext2_check_descriptors (struct super_block * sb)
 543 {
 544         int i;
 545         int desc_block = 0;
 546         struct ext2_sb_info *sbi = EXT2_SB(sb);
 547         unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 548         unsigned long last_block;
 549         struct ext2_group_desc * gdp = NULL;
 550
 551         ext2_debug ("Checking group descriptors");
 552
 553         for (i = 0; i < sbi->s_groups_count; i++)
 554         {
 555                 if (i == sbi->s_groups_count - 1)
 556                         last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
 557                 else
 558                         last_block = first_block +
 559                                 (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 560
 561                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 562                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 563                 if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
 564                     le32_to_cpu(gdp->bg_block_bitmap) > last_block)
 565                 {
 566                         ext2_error (sb, "ext2_check_descriptors",
 567                                     "Block bitmap for group %d"
 568                                     " not in group (block %lu)!",
 569                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 570                         return 0;
 571                 }
 572                 if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
 573                     le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
 574                 {
 575                         ext2_error (sb, "ext2_check_descriptors",
 576                                     "Inode bitmap for group %d"
 577                                     " not in group (block %lu)!",
 578                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 579                         return 0;
 580                 }
 581                 if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
 582                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
 583                     last_block)
 584                 {
 585                         ext2_error (sb, "ext2_check_descriptors",
 586                                     "Inode table for group %d"
 587                                     " not in group (block %lu)!",
 588                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 589                         return 0;
 590                 }
 591                 first_block += EXT2_BLOCKS_PER_GROUP(sb);
 592                 gdp++;
 593         }
 594         return 1;
 595 }
 596
 597 #define log2(n) ffz(~(n))
 598
 599 /*
 600  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 601  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 602  * We need to be 1 filesystem block less than the 2^32 sector limit.
 603  */
 604 static loff_t ext2_max_size(int bits)
 605 {
 606         loff_t res = EXT2_NDIR_BLOCKS;
 607         /* This constant is calculated to be the largest file size for a
 608          * dense, 4k-blocksize file such that the total number of
 609          * sectors in the file, including data and all indirect blocks,
 610          * does not exceed 2^32. */
 611         const loff_t upper_limit = 0x1ff7fffd000LL;
 612
 613         res += 1LL << (bits-2);
 614         res += 1LL << (2*(bits-2));
 615         res += 1LL << (3*(bits-2));
 616         res <<= bits;
 617         if (res > upper_limit)
 618                 res = upper_limit;
 619         return res;
 620 }
 621
 622 static unsigned long descriptor_loc(struct super_block *sb,
 623                                     unsigned long logic_sb_block,
 624                                     int nr)
 625 {
 626         struct ext2_sb_info *sbi = EXT2_SB(sb);
 627         unsigned long bg, first_data_block, first_meta_bg;
 628         int has_super = 0;
 629
 630         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 631         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 632
 633         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 634             nr < first_meta_bg)
 635                 return (logic_sb_block + nr + 1);
 636         bg = sbi->s_desc_per_block * nr;
 637         if (ext2_bg_has_super(sb, bg))
 638                 has_super = 1;
 639         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 640 }
 641
 642 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 643 {
 644         struct buffer_head * bh;
 645         struct ext2_sb_info * sbi;
 646         struct ext2_super_block * es;
 647         struct inode *root;
 648         unsigned long block;
 649         unsigned long sb_block = get_sb_block(&data);
 650         unsigned long logic_sb_block;
 651         unsigned long offset = 0;
 652         unsigned long def_mount_opts;
 653         int blocksize = BLOCK_SIZE;
 654         int db_count;
 655         int i, j;
 656         __le32 features;
 657
 658         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 659         if (!sbi)
 660                 return -ENOMEM;
 661         sb->s_fs_info = sbi;
 662
 663         /*
 664          * See what the current blocksize for the device is, and
 665          * use that as the blocksize.  Otherwise (or if the blocksize
 666          * is smaller than the default) use the default.
 667          * This is important for devices that have a hardware
 668          * sectorsize that is larger than the default.
 669          */
 670         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 671         if (!blocksize) {
 672                 printk ("EXT2-fs: unable to set blocksize\n");
 673                 goto failed_sbi;
 674         }
 675
 676         /*
 677          * If the superblock doesn't start on a hardware sector boundary,
 678          * calculate the offset.
 679          */
 680         if (blocksize != BLOCK_SIZE) {
 681                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 682                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 683         } else {
 684                 logic_sb_block = sb_block;
 685         }
 686
 687         if (!(bh = sb_bread(sb, logic_sb_block))) {
 688                 printk ("EXT2-fs: unable to read superblock\n");
 689                 goto failed_sbi;
 690         }
 691         /*
 692          * Note: s_es must be initialized as soon as possible because
 693          *       some ext2 macro-instructions depend on its value
 694          */
 695         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 696         sbi->s_es = es;
 697         sb->s_magic = le16_to_cpu(es->s_magic);
 698
 699         if (sb->s_magic != EXT2_SUPER_MAGIC)
 700                 goto cantfind_ext2;
 701
 702         /* Set defaults before we parse the mount options */
 703         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 704         if (def_mount_opts & EXT2_DEFM_DEBUG)
 705                 set_opt(sbi->s_mount_opt, DEBUG);
 706         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 707                 set_opt(sbi->s_mount_opt, GRPID);
 708         if (def_mount_opts & EXT2_DEFM_UID16)
 709                 set_opt(sbi->s_mount_opt, NO_UID32);
 710         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 711                 set_opt(sbi->s_mount_opt, XATTR_USER);
 712         if (def_mount_opts & EXT2_DEFM_ACL)
 713                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 714
 715         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 716                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 717         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 718                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 719
 720         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 721         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 722
 723         if (!parse_options ((char *) data, sbi))
 724                 goto failed_mount;
 725
 726         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 727                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 728                  MS_POSIXACL : 0);
 729
 730         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 731                                     EXT2_MOUNT_XIP if not */
 732
 733         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 734             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 735              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 736              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 737                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 738                        "running e2fsck is recommended\n");
 739         /*
 740          * Check feature flags regardless of the revision level, since we
 741          * previously didn't change the revision level when setting the flags,
 742          * so there is a chance incompat flags are set on a rev 0 filesystem.
 743          */
 744         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 745         if (features) {
 746                 printk("EXT2-fs: %s: couldn't mount because of "
 747                        "unsupported optional features (%x).\n",
 748                        sb->s_id, le32_to_cpu(features));
 749                 goto failed_mount;
 750         }
 751         if (!(sb->s_flags & MS_RDONLY) &&
 752             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 753                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 754                        "unsupported optional features (%x).\n",
 755                        sb->s_id, le32_to_cpu(features));
 756                 goto failed_mount;
 757         }
 758
 759         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 760
 761         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 762                                   (sb->s_blocksize != blocksize))) {
 763                 if (!silent)
 764                         printk("XIP: Unsupported blocksize\n");
 765                 goto failed_mount;
 766         }
 767
 768         /* If the blocksize doesn't match, re-read the thing.. */
 769         if (sb->s_blocksize != blocksize) {
 770                 brelse(bh);
 771
 772                 if (!sb_set_blocksize(sb, blocksize)) {
 773                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 774                         goto failed_sbi;
 775                 }
 776
 777                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 778                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 779                 bh = sb_bread(sb, logic_sb_block);
 780                 if(!bh) {
 781                         printk("EXT2-fs: Couldn't read superblock on "
 782                                "2nd try.\n");
 783                         goto failed_sbi;
 784                 }
 785                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 786                 sbi->s_es = es;
 787                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 788                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 789                         goto failed_mount;
 790                 }
 791         }
 792
 793         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 794
 795         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 796                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 797                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 798         } else {
 799                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 800                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 801                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 802                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 803                     (sbi->s_inode_size > blocksize)) {
 804                         printk ("EXT2-fs: unsupported inode size: %d\n",
 805                                 sbi->s_inode_size);
 806                         goto failed_mount;
 807                 }
 808         }
 809
 810         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 811                                    le32_to_cpu(es->s_log_frag_size);
 812         if (sbi->s_frag_size == 0)
 813                 goto cantfind_ext2;
 814         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 815
 816         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 817         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 818         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 819
 820         if (EXT2_INODE_SIZE(sb) == 0)
 821                 goto cantfind_ext2;
 822         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 823         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
 824                 goto cantfind_ext2;
 825         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 826                                         sbi->s_inodes_per_block;
 827         sbi->s_desc_per_block = sb->s_blocksize /
 828                                         sizeof (struct ext2_group_desc);
 829         sbi->s_sbh = bh;
 830         sbi->s_mount_state = le16_to_cpu(es->s_state);
 831         sbi->s_addr_per_block_bits =
 832                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 833         sbi->s_desc_per_block_bits =
 834                 log2 (EXT2_DESC_PER_BLOCK(sb));
 835
 836         if (sb->s_magic != EXT2_SUPER_MAGIC)
 837                 goto cantfind_ext2;
 838
 839         if (sb->s_blocksize != bh->b_size) {
 840                 if (!silent)
 841                         printk ("VFS: Unsupported blocksize on dev "
 842                                 "%s.\n", sb->s_id);
 843                 goto failed_mount;
 844         }
 845
 846         if (sb->s_blocksize != sbi->s_frag_size) {
 847                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 848                         sbi->s_frag_size, sb->s_blocksize);
 849                 goto failed_mount;
 850         }
 851
 852         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 853                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 854                         sbi->s_blocks_per_group);
 855                 goto failed_mount;
 856         }
 857         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 858                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 859                         sbi->s_frags_per_group);
 860                 goto failed_mount;
 861         }
 862         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 863                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 864                         sbi->s_inodes_per_group);
 865                 goto failed_mount;
 866         }
 867
 868         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 869                 goto cantfind_ext2;
 870         sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
 871                                 le32_to_cpu(es->s_first_data_block) - 1)
 872                                         / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
 873         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 874                    EXT2_DESC_PER_BLOCK(sb);
 875         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 876         if (sbi->s_group_desc == NULL) {
 877                 printk ("EXT2-fs: not enough memory\n");
 878                 goto failed_mount;
 879         }
 880         bgl_lock_init(&sbi->s_blockgroup_lock);
 881         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 882                                GFP_KERNEL);
 883         if (!sbi->s_debts) {
 884                 printk ("EXT2-fs: not enough memory\n");
 885                 goto failed_mount_group_desc;
 886         }
 887         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 888         for (i = 0; i < db_count; i++) {
 889                 block = descriptor_loc(sb, logic_sb_block, i);
 890                 sbi->s_group_desc[i] = sb_bread(sb, block);
 891                 if (!sbi->s_group_desc[i]) {
 892                         for (j = 0; j < i; j++)
 893                                 brelse (sbi->s_group_desc[j]);
 894                         printk ("EXT2-fs: unable to read group descriptors\n");
 895                         goto failed_mount_group_desc;
 896                 }
 897         }
 898         if (!ext2_check_descriptors (sb)) {
 899                 printk ("EXT2-fs: group descriptors corrupted!\n");
 900                 goto failed_mount2;
 901         }
 902         sbi->s_gdb_count = db_count;
 903         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 904         spin_lock_init(&sbi->s_next_gen_lock);
 905
 906         percpu_counter_init(&sbi->s_freeblocks_counter,
 907                                 ext2_count_free_blocks(sb));
 908         percpu_counter_init(&sbi->s_freeinodes_counter,
 909                                 ext2_count_free_inodes(sb));
 910         percpu_counter_init(&sbi->s_dirs_counter,
 911                                 ext2_count_dirs(sb));
 912         /*
 913          * set up enough so that it can read an inode
 914          */
 915         sb->s_op = &ext2_sops;
 916         sb->s_export_op = &ext2_export_ops;
 917         sb->s_xattr = ext2_xattr_handlers;
 918         root = iget(sb, EXT2_ROOT_INO);
 919         sb->s_root = d_alloc_root(root);
 920         if (!sb->s_root) {
 921                 iput(root);
 922                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 923                 goto failed_mount3;
 924         }
 925         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 926                 dput(sb->s_root);
 927                 sb->s_root = NULL;
 928                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 929                 goto failed_mount3;
 930         }
 931         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 932                 ext2_warning(sb, __FUNCTION__,
 933                         "mounting ext3 filesystem as ext2");
 934         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 935         return 0;
 936
 937 cantfind_ext2:
 938         if (!silent)
 939                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 940                        sb->s_id);
 941         goto failed_mount;
 942 failed_mount3:
 943         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 944         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 945         percpu_counter_destroy(&sbi->s_dirs_counter);
 946 failed_mount2:
 947         for (i = 0; i < db_count; i++)
 948                 brelse(sbi->s_group_desc[i]);
 949 failed_mount_group_desc:
 950         kfree(sbi->s_group_desc);
 951         kfree(sbi->s_debts);
 952 failed_mount:
 953         brelse(bh);
 954 failed_sbi:
 955         sb->s_fs_info = NULL;
 956         kfree(sbi);
 957         return -EINVAL;
 958 }
 959
 960 static void ext2_commit_super (struct super_block * sb,
 961                                struct ext2_super_block * es)
 962 {
 963         es->s_wtime = cpu_to_le32(get_seconds());
 964         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 965         sb->s_dirt = 0;
 966 }
 967
 968 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 969 {
 970         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 971         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 972         es->s_wtime = cpu_to_le32(get_seconds());
 973         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 974         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 975         sb->s_dirt = 0;
 976 }
 977
 978 /*
 979  * In the second extended file system, it is not necessary to
 980  * write the super block since we use a mapping of the
 981  * disk super block in a buffer.
 982  *
 983  * However, this function is still used to set the fs valid
 984  * flags to 0.  We need to set this flag to 0 since the fs
 985  * may have been checked while mounted and e2fsck may have
 986  * set s_state to EXT2_VALID_FS after some corrections.
 987  */
 988
 989 void ext2_write_super (struct super_block * sb)
 990 {
 991         struct ext2_super_block * es;
 992         lock_kernel();
 993         if (!(sb->s_flags & MS_RDONLY)) {
 994                 es = EXT2_SB(sb)->s_es;
 995
 996                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
 997                         ext2_debug ("setting valid to 0\n");
 998                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
 999                                                   ~EXT2_VALID_FS);
1000                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1001                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1002                         es->s_mtime = cpu_to_le32(get_seconds());
1003                         ext2_sync_super(sb, es);
1004                 } else
1005                         ext2_commit_super (sb, es);
1006         }
1007         sb->s_dirt = 0;
1008         unlock_kernel();
1009 }
1010
1011 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1012 {
1013         struct ext2_sb_info * sbi = EXT2_SB(sb);
1014         struct ext2_super_block * es;
1015         unsigned long old_mount_opt = sbi->s_mount_opt;
1016         struct ext2_mount_options old_opts;
1017         unsigned long old_sb_flags;
1018         int err;
1019
1020         /* Store the old options */
1021         old_sb_flags = sb->s_flags;
1022         old_opts.s_mount_opt = sbi->s_mount_opt;
1023         old_opts.s_resuid = sbi->s_resuid;
1024         old_opts.s_resgid = sbi->s_resgid;
1025
1026         /*
1027          * Allow the "check" option to be passed as a remount option.
1028          */
1029         if (!parse_options (data, sbi)) {
1030                 err = -EINVAL;
1031                 goto restore_opts;
1032         }
1033
1034         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1035                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1036
1037         es = sbi->s_es;
1038         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1039             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1040             invalidate_inodes(sb))
1041                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1042                              "xip remain in cache (no functional problem)");
1043         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1044                 return 0;
1045         if (*flags & MS_RDONLY) {
1046                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1047                     !(sbi->s_mount_state & EXT2_VALID_FS))
1048                         return 0;
1049                 /*
1050                  * OK, we are remounting a valid rw partition rdonly, so set
1051                  * the rdonly flag and then mark the partition as valid again.
1052                  */
1053                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1054                 es->s_mtime = cpu_to_le32(get_seconds());
1055         } else {
1056                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1057                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1058                 if (ret) {
1059                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1060                                "unsupported optional features (%x).\n",
1061                                sb->s_id, le32_to_cpu(ret));
1062                         err = -EROFS;
1063                         goto restore_opts;
1064                 }
1065                 /*
1066                  * Mounting a RDONLY partition read-write, so reread and
1067                  * store the current valid flag.  (It may have been changed
1068                  * by e2fsck since we originally mounted the partition.)
1069                  */
1070                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1071                 if (!ext2_setup_super (sb, es, 0))
1072                         sb->s_flags &= ~MS_RDONLY;
1073         }
1074         ext2_sync_super(sb, es);
1075         return 0;
1076 restore_opts:
1077         sbi->s_mount_opt = old_opts.s_mount_opt;
1078         sbi->s_resuid = old_opts.s_resuid;
1079         sbi->s_resgid = old_opts.s_resgid;
1080         sb->s_flags = old_sb_flags;
1081         return err;
1082 }
1083
1084 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1085 {
1086         struct super_block *sb = dentry->d_sb;
1087         struct ext2_sb_info *sbi = EXT2_SB(sb);
1088         unsigned long overhead;
1089         int i;
1090
1091         if (test_opt (sb, MINIX_DF))
1092                 overhead = 0;
1093         else {
1094                 /*
1095                  * Compute the overhead (FS structures)
1096                  */
1097
1098                 /*
1099                  * All of the blocks before first_data_block are
1100                  * overhead
1101                  */
1102                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1103
1104                 /*
1105                  * Add the overhead attributed to the superblock and
1106                  * block group descriptors.  If the sparse superblocks
1107                  * feature is turned on, then not all groups have this.
1108                  */
1109                 for (i = 0; i < sbi->s_groups_count; i++)
1110                         overhead += ext2_bg_has_super(sb, i) +
1111                                 ext2_bg_num_gdb(sb, i);
1112
1113                 /*
1114                  * Every block group has an inode bitmap, a block
1115                  * bitmap, and an inode table.
1116                  */
1117                 overhead += (sbi->s_groups_count *
1118                              (2 + sbi->s_itb_per_group));
1119         }
1120
1121         buf->f_type = EXT2_SUPER_MAGIC;
1122         buf->f_bsize = sb->s_blocksize;
1123         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1124         buf->f_bfree = ext2_count_free_blocks(sb);
1125         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1126         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1127                 buf->f_bavail = 0;
1128         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1129         buf->f_ffree = ext2_count_free_inodes (sb);
1130         buf->f_namelen = EXT2_NAME_LEN;
1131         return 0;
1132 }
1133
1134 static int ext2_get_sb(struct file_system_type *fs_type,
1135         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1136 {
1137         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1138 }
1139
1140 #ifdef CONFIG_QUOTA
1141
1142 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1143  * acquiring the locks... As quota files are never truncated and quota code
1144  * itself serializes the operations (and noone else should touch the files)
1145  * we don't have to be afraid of races */
1146 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1147                                size_t len, loff_t off)
1148 {
1149         struct inode *inode = sb_dqopt(sb)->files[type];
1150         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1151         int err = 0;
1152         int offset = off & (sb->s_blocksize - 1);
1153         int tocopy;
1154         size_t toread;
1155         struct buffer_head tmp_bh;
1156         struct buffer_head *bh;
1157         loff_t i_size = i_size_read(inode);
1158
1159         if (off > i_size)
1160                 return 0;
1161         if (off+len > i_size)
1162                 len = i_size-off;
1163         toread = len;
1164         while (toread > 0) {
1165                 tocopy = sb->s_blocksize - offset < toread ?
1166                                 sb->s_blocksize - offset : toread;
1167
1168                 tmp_bh.b_state = 0;
1169                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1170                 if (err)
1171                         return err;
1172                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1173                         memset(data, 0, tocopy);
1174                 else {
1175                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1176                         if (!bh)
1177                                 return -EIO;
1178                         memcpy(data, bh->b_data+offset, tocopy);
1179                         brelse(bh);
1180                 }
1181                 offset = 0;
1182                 toread -= tocopy;
1183                 data += tocopy;
1184                 blk++;
1185         }
1186         return len;
1187 }
1188
1189 /* Write to quotafile */
1190 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1191                                 const char *data, size_t len, loff_t off)
1192 {
1193         struct inode *inode = sb_dqopt(sb)->files[type];
1194         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1195         int err = 0;
1196         int offset = off & (sb->s_blocksize - 1);
1197         int tocopy;
1198         size_t towrite = len;
1199         struct buffer_head tmp_bh;
1200         struct buffer_head *bh;
1201
1202         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1203         while (towrite > 0) {
1204                 tocopy = sb->s_blocksize - offset < towrite ?
1205                                 sb->s_blocksize - offset : towrite;
1206
1207                 tmp_bh.b_state = 0;
1208                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1209                 if (err)
1210                         goto out;
1211                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1212                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1213                 else
1214                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1215                 if (!bh) {
1216                         err = -EIO;
1217                         goto out;
1218                 }
1219                 lock_buffer(bh);
1220                 memcpy(bh->b_data+offset, data, tocopy);
1221                 flush_dcache_page(bh->b_page);
1222                 set_buffer_uptodate(bh);
1223                 mark_buffer_dirty(bh);
1224                 unlock_buffer(bh);
1225                 brelse(bh);
1226                 offset = 0;
1227                 towrite -= tocopy;
1228                 data += tocopy;
1229                 blk++;
1230         }
1231 out:
1232         if (len == towrite)
1233                 return err;
1234         if (inode->i_size < off+len-towrite)
1235                 i_size_write(inode, off+len-towrite);
1236         inode->i_version++;
1237         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1238         mark_inode_dirty(inode);
1239         mutex_unlock(&inode->i_mutex);
1240         return len - towrite;
1241 }
1242
1243 #endif
1244
1245 static struct file_system_type ext2_fs_type = {
1246         .owner          = THIS_MODULE,
1247         .name           = "ext2",
1248         .get_sb         = ext2_get_sb,
1249         .kill_sb        = kill_block_super,
1250         .fs_flags       = FS_REQUIRES_DEV,
1251 };
1252
1253 static int __init init_ext2_fs(void)
1254 {
1255         int err = init_ext2_xattr();
1256         if (err)
1257                 return err;
1258         err = init_inodecache();
1259         if (err)
1260                 goto out1;
1261         err = register_filesystem(&ext2_fs_type);
1262         if (err)
1263                 goto out;
1264         return 0;
1265 out:
1266         destroy_inodecache();
1267 out1:
1268         exit_ext2_xattr();
1269         return err;
1270 }
1271
1272 static void __exit exit_ext2_fs(void)
1273 {
1274         unregister_filesystem(&ext2_fs_type);
1275         destroy_inodecache();
1276         exit_ext2_xattr();
1277 }
1278
1279 module_init(init_ext2_fs)
1280 module_exit(exit_ext2_fs)