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, Opt_tagxid
 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_tagxid, "tagxid"},
 357         {Opt_grpquota, "grpquota"},
 358         {Opt_ignore, "noquota"},
 359         {Opt_quota, "quota"},
 360         {Opt_usrquota, "usrquota"},
 361         {Opt_err, NULL}
 362 };
 363
 364 static int parse_options (char * options,
 365                           struct ext2_sb_info *sbi)
 366 {
 367         char * p;
 368         substring_t args[MAX_OPT_ARGS];
 369         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 370         int option;
 371
 372         if (!options)
 373                 return 1;
 374
 375         while ((p = strsep (&options, ",")) != NULL) {
 376                 int token;
 377                 if (!*p)
 378                         continue;
 379
 380                 token = match_token(p, tokens, args);
 381                 switch (token) {
 382                 case Opt_bsd_df:
 383                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 384                         break;
 385                 case Opt_minix_df:
 386                         set_opt (sbi->s_mount_opt, MINIX_DF);
 387                         break;
 388                 case Opt_grpid:
 389                         set_opt (sbi->s_mount_opt, GRPID);
 390                         break;
 391                 case Opt_nogrpid:
 392                         clear_opt (sbi->s_mount_opt, GRPID);
 393                         break;
 394                 case Opt_resuid:
 395                         if (match_int(&args[0], &option))
 396                                 return 0;
 397                         sbi->s_resuid = option;
 398                         break;
 399                 case Opt_resgid:
 400                         if (match_int(&args[0], &option))
 401                                 return 0;
 402                         sbi->s_resgid = option;
 403                         break;
 404                 case Opt_sb:
 405                         /* handled by get_sb_block() instead of here */
 406                         /* *sb_block = match_int(&args[0]); */
 407                         break;
 408                 case Opt_err_panic:
 409                         kind = EXT2_MOUNT_ERRORS_PANIC;
 410                         break;
 411                 case Opt_err_ro:
 412                         kind = EXT2_MOUNT_ERRORS_RO;
 413                         break;
 414                 case Opt_err_cont:
 415                         kind = EXT2_MOUNT_ERRORS_CONT;
 416                         break;
 417                 case Opt_nouid32:
 418                         set_opt (sbi->s_mount_opt, NO_UID32);
 419                         break;
 420 #ifndef CONFIG_INOXID_NONE
 421                 case Opt_tagxid:
 422                         set_opt (sbi->s_mount_opt, TAGXID);
 423                         break;
 424 #endif
 425                 case Opt_nocheck:
 426                         clear_opt (sbi->s_mount_opt, CHECK);
 427                         break;
 428                 case Opt_debug:
 429                         set_opt (sbi->s_mount_opt, DEBUG);
 430                         break;
 431                 case Opt_oldalloc:
 432                         set_opt (sbi->s_mount_opt, OLDALLOC);
 433                         break;
 434                 case Opt_orlov:
 435                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 436                         break;
 437                 case Opt_nobh:
 438                         set_opt (sbi->s_mount_opt, NOBH);
 439                         break;
 440 #ifdef CONFIG_EXT2_FS_XATTR
 441                 case Opt_user_xattr:
 442                         set_opt (sbi->s_mount_opt, XATTR_USER);
 443                         break;
 444                 case Opt_nouser_xattr:
 445                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 446                         break;
 447 #else
 448                 case Opt_user_xattr:
 449                 case Opt_nouser_xattr:
 450                         printk("EXT2 (no)user_xattr options not supported\n");
 451                         break;
 452 #endif
 453 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 454                 case Opt_acl:
 455                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 456                         break;
 457                 case Opt_noacl:
 458                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 459                         break;
 460 #else
 461                 case Opt_acl:
 462                 case Opt_noacl:
 463                         printk("EXT2 (no)acl options not supported\n");
 464                         break;
 465 #endif
 466                 case Opt_xip:
 467 #ifdef CONFIG_EXT2_FS_XIP
 468                         set_opt (sbi->s_mount_opt, XIP);
 469 #else
 470                         printk("EXT2 xip option not supported\n");
 471 #endif
 472                         break;
 473
 474 #if defined(CONFIG_QUOTA)
 475                 case Opt_quota:
 476                 case Opt_usrquota:
 477                         set_opt(sbi->s_mount_opt, USRQUOTA);
 478                         break;
 479
 480                 case Opt_grpquota:
 481                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 482                         break;
 483 #else
 484                 case Opt_quota:
 485                 case Opt_usrquota:
 486                 case Opt_grpquota:
 487                         printk(KERN_ERR
 488                                 "EXT2-fs: quota operations not supported.\n");
 489
 490                         break;
 491 #endif
 492
 493                 case Opt_ignore:
 494                         break;
 495                 default:
 496                         return 0;
 497                 }
 498         }
 499         sbi->s_mount_opt |= kind;
 500         return 1;
 501 }
 502
 503 static int ext2_setup_super (struct super_block * sb,
 504                               struct ext2_super_block * es,
 505                               int read_only)
 506 {
 507         int res = 0;
 508         struct ext2_sb_info *sbi = EXT2_SB(sb);
 509
 510         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 511                 printk ("EXT2-fs warning: revision level too high, "
 512                         "forcing read-only mode\n");
 513                 res = MS_RDONLY;
 514         }
 515         if (read_only)
 516                 return res;
 517         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 518                 printk ("EXT2-fs warning: mounting unchecked fs, "
 519                         "running e2fsck is recommended\n");
 520         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 521                 printk ("EXT2-fs warning: mounting fs with errors, "
 522                         "running e2fsck is recommended\n");
 523         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 524                  le16_to_cpu(es->s_mnt_count) >=
 525                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 526                 printk ("EXT2-fs warning: maximal mount count reached, "
 527                         "running e2fsck is recommended\n");
 528         else if (le32_to_cpu(es->s_checkinterval) &&
 529                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 530                 printk ("EXT2-fs warning: checktime reached, "
 531                         "running e2fsck is recommended\n");
 532         if (!le16_to_cpu(es->s_max_mnt_count))
 533                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 534         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 535         ext2_write_super(sb);
 536         if (test_opt (sb, DEBUG))
 537                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 538                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 539                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 540                         sbi->s_frag_size,
 541                         sbi->s_groups_count,
 542                         EXT2_BLOCKS_PER_GROUP(sb),
 543                         EXT2_INODES_PER_GROUP(sb),
 544                         sbi->s_mount_opt);
 545         return res;
 546 }
 547
 548 static int ext2_check_descriptors (struct super_block * sb)
 549 {
 550         int i;
 551         int desc_block = 0;
 552         struct ext2_sb_info *sbi = EXT2_SB(sb);
 553         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
 554         struct ext2_group_desc * gdp = NULL;
 555
 556         ext2_debug ("Checking group descriptors");
 557
 558         for (i = 0; i < sbi->s_groups_count; i++)
 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) < block ||
 563                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 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) < block ||
 572                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 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) < block ||
 581                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
 582                     block + EXT2_BLOCKS_PER_GROUP(sb))
 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                 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 = kmalloc(sizeof(*sbi), GFP_KERNEL);
 658         if (!sbi)
 659                 return -ENOMEM;
 660         sb->s_fs_info = sbi;
 661         memset(sbi, 0, sizeof(*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         if (EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_TAGXID)
 727                 sb->s_flags |= MS_TAGXID;
 728         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 729                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 730                  MS_POSIXACL : 0);
 731
 732         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 733                                     EXT2_MOUNT_XIP if not */
 734
 735         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 736             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 737              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 738              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 739                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 740                        "running e2fsck is recommended\n");
 741         /*
 742          * Check feature flags regardless of the revision level, since we
 743          * previously didn't change the revision level when setting the flags,
 744          * so there is a chance incompat flags are set on a rev 0 filesystem.
 745          */
 746         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 747         if (features) {
 748                 printk("EXT2-fs: %s: couldn't mount because of "
 749                        "unsupported optional features (%x).\n",
 750                        sb->s_id, le32_to_cpu(features));
 751                 goto failed_mount;
 752         }
 753         if (!(sb->s_flags & MS_RDONLY) &&
 754             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 755                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 756                        "unsupported optional features (%x).\n",
 757                        sb->s_id, le32_to_cpu(features));
 758                 goto failed_mount;
 759         }
 760
 761         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 762
 763         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 764                                   (sb->s_blocksize != blocksize))) {
 765                 if (!silent)
 766                         printk("XIP: Unsupported blocksize\n");
 767                 goto failed_mount;
 768         }
 769
 770         /* If the blocksize doesn't match, re-read the thing.. */
 771         if (sb->s_blocksize != blocksize) {
 772                 brelse(bh);
 773
 774                 if (!sb_set_blocksize(sb, blocksize)) {
 775                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 776                         goto failed_sbi;
 777                 }
 778
 779                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 780                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 781                 bh = sb_bread(sb, logic_sb_block);
 782                 if(!bh) {
 783                         printk("EXT2-fs: Couldn't read superblock on "
 784                                "2nd try.\n");
 785                         goto failed_sbi;
 786                 }
 787                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 788                 sbi->s_es = es;
 789                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 790                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 791                         goto failed_mount;
 792                 }
 793         }
 794
 795         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 796
 797         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 798                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 799                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 800         } else {
 801                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 802                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 803                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 804                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 805                     (sbi->s_inode_size > blocksize)) {
 806                         printk ("EXT2-fs: unsupported inode size: %d\n",
 807                                 sbi->s_inode_size);
 808                         goto failed_mount;
 809                 }
 810         }
 811
 812         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 813                                    le32_to_cpu(es->s_log_frag_size);
 814         if (sbi->s_frag_size == 0)
 815                 goto cantfind_ext2;
 816         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 817
 818         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 819         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 820         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 821
 822         if (EXT2_INODE_SIZE(sb) == 0)
 823                 goto cantfind_ext2;
 824         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 825         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
 826                 goto cantfind_ext2;
 827         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 828                                         sbi->s_inodes_per_block;
 829         sbi->s_desc_per_block = sb->s_blocksize /
 830                                         sizeof (struct ext2_group_desc);
 831         sbi->s_sbh = bh;
 832         sbi->s_mount_state = le16_to_cpu(es->s_state);
 833         sbi->s_addr_per_block_bits =
 834                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 835         sbi->s_desc_per_block_bits =
 836                 log2 (EXT2_DESC_PER_BLOCK(sb));
 837
 838         if (sb->s_magic != EXT2_SUPER_MAGIC)
 839                 goto cantfind_ext2;
 840
 841         if (sb->s_blocksize != bh->b_size) {
 842                 if (!silent)
 843                         printk ("VFS: Unsupported blocksize on dev "
 844                                 "%s.\n", sb->s_id);
 845                 goto failed_mount;
 846         }
 847
 848         if (sb->s_blocksize != sbi->s_frag_size) {
 849                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 850                         sbi->s_frag_size, sb->s_blocksize);
 851                 goto failed_mount;
 852         }
 853
 854         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 855                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 856                         sbi->s_blocks_per_group);
 857                 goto failed_mount;
 858         }
 859         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 860                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 861                         sbi->s_frags_per_group);
 862                 goto failed_mount;
 863         }
 864         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 865                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 866                         sbi->s_inodes_per_group);
 867                 goto failed_mount;
 868         }
 869
 870         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 871                 goto cantfind_ext2;
 872         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
 873                                         le32_to_cpu(es->s_first_data_block) +
 874                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 875                                        EXT2_BLOCKS_PER_GROUP(sb);
 876         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 877                    EXT2_DESC_PER_BLOCK(sb);
 878         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 879         if (sbi->s_group_desc == NULL) {
 880                 printk ("EXT2-fs: not enough memory\n");
 881                 goto failed_mount;
 882         }
 883         bgl_lock_init(&sbi->s_blockgroup_lock);
 884         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 885                                GFP_KERNEL);
 886         if (!sbi->s_debts) {
 887                 printk ("EXT2-fs: not enough memory\n");
 888                 goto failed_mount_group_desc;
 889         }
 890         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 891         for (i = 0; i < db_count; i++) {
 892                 block = descriptor_loc(sb, logic_sb_block, i);
 893                 sbi->s_group_desc[i] = sb_bread(sb, block);
 894                 if (!sbi->s_group_desc[i]) {
 895                         for (j = 0; j < i; j++)
 896                                 brelse (sbi->s_group_desc[j]);
 897                         printk ("EXT2-fs: unable to read group descriptors\n");
 898                         goto failed_mount_group_desc;
 899                 }
 900         }
 901         if (!ext2_check_descriptors (sb)) {
 902                 printk ("EXT2-fs: group descriptors corrupted!\n");
 903                 goto failed_mount2;
 904         }
 905         sbi->s_gdb_count = db_count;
 906         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 907         spin_lock_init(&sbi->s_next_gen_lock);
 908
 909         percpu_counter_init(&sbi->s_freeblocks_counter,
 910                                 ext2_count_free_blocks(sb));
 911         percpu_counter_init(&sbi->s_freeinodes_counter,
 912                                 ext2_count_free_inodes(sb));
 913         percpu_counter_init(&sbi->s_dirs_counter,
 914                                 ext2_count_dirs(sb));
 915         /*
 916          * set up enough so that it can read an inode
 917          */
 918         sb->s_op = &ext2_sops;
 919         sb->s_export_op = &ext2_export_ops;
 920         sb->s_xattr = ext2_xattr_handlers;
 921         root = iget(sb, EXT2_ROOT_INO);
 922         sb->s_root = d_alloc_root(root);
 923         if (!sb->s_root) {
 924                 iput(root);
 925                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 926                 goto failed_mount3;
 927         }
 928         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 929                 dput(sb->s_root);
 930                 sb->s_root = NULL;
 931                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 932                 goto failed_mount3;
 933         }
 934         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 935                 ext2_warning(sb, __FUNCTION__,
 936                         "mounting ext3 filesystem as ext2");
 937         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 938         return 0;
 939
 940 cantfind_ext2:
 941         if (!silent)
 942                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 943                        sb->s_id);
 944         goto failed_mount;
 945 failed_mount3:
 946         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 947         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 948         percpu_counter_destroy(&sbi->s_dirs_counter);
 949 failed_mount2:
 950         for (i = 0; i < db_count; i++)
 951                 brelse(sbi->s_group_desc[i]);
 952 failed_mount_group_desc:
 953         kfree(sbi->s_group_desc);
 954         kfree(sbi->s_debts);
 955 failed_mount:
 956         brelse(bh);
 957 failed_sbi:
 958         sb->s_fs_info = NULL;
 959         kfree(sbi);
 960         return -EINVAL;
 961 }
 962
 963 static void ext2_commit_super (struct super_block * sb,
 964                                struct ext2_super_block * es)
 965 {
 966         es->s_wtime = cpu_to_le32(get_seconds());
 967         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 968         sb->s_dirt = 0;
 969 }
 970
 971 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 972 {
 973         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 974         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 975         es->s_wtime = cpu_to_le32(get_seconds());
 976         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 977         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 978         sb->s_dirt = 0;
 979 }
 980
 981 /*
 982  * In the second extended file system, it is not necessary to
 983  * write the super block since we use a mapping of the
 984  * disk super block in a buffer.
 985  *
 986  * However, this function is still used to set the fs valid
 987  * flags to 0.  We need to set this flag to 0 since the fs
 988  * may have been checked while mounted and e2fsck may have
 989  * set s_state to EXT2_VALID_FS after some corrections.
 990  */
 991
 992 void ext2_write_super (struct super_block * sb)
 993 {
 994         struct ext2_super_block * es;
 995         lock_kernel();
 996         if (!(sb->s_flags & MS_RDONLY)) {
 997                 es = EXT2_SB(sb)->s_es;
 998
 999                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1000                         ext2_debug ("setting valid to 0\n");
1001                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1002                                                   ~EXT2_VALID_FS);
1003                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1004                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1005                         es->s_mtime = cpu_to_le32(get_seconds());
1006                         ext2_sync_super(sb, es);
1007                 } else
1008                         ext2_commit_super (sb, es);
1009         }
1010         sb->s_dirt = 0;
1011         unlock_kernel();
1012 }
1013
1014 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1015 {
1016         struct ext2_sb_info * sbi = EXT2_SB(sb);
1017         struct ext2_super_block * es;
1018         unsigned long old_mount_opt = sbi->s_mount_opt;
1019         struct ext2_mount_options old_opts;
1020         unsigned long old_sb_flags;
1021         int err;
1022
1023         /* Store the old options */
1024         old_sb_flags = sb->s_flags;
1025         old_opts.s_mount_opt = sbi->s_mount_opt;
1026         old_opts.s_resuid = sbi->s_resuid;
1027         old_opts.s_resgid = sbi->s_resgid;
1028
1029         /*
1030          * Allow the "check" option to be passed as a remount option.
1031          */
1032         if (!parse_options (data, sbi)) {
1033                 err = -EINVAL;
1034                 goto restore_opts;
1035         }
1036
1037         if ((sbi->s_mount_opt & EXT2_MOUNT_TAGXID) &&
1038                 !(sb->s_flags & MS_TAGXID)) {
1039                 printk("EXT2-fs: %s: tagxid not permitted on remount.\n",
1040                        sb->s_id);
1041                 return -EINVAL;
1042         }
1043
1044         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1045                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1046
1047         es = sbi->s_es;
1048         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1049             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1050             invalidate_inodes(sb))
1051                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1052                              "xip remain in cache (no functional problem)");
1053         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1054                 return 0;
1055         if (*flags & MS_RDONLY) {
1056                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1057                     !(sbi->s_mount_state & EXT2_VALID_FS))
1058                         return 0;
1059                 /*
1060                  * OK, we are remounting a valid rw partition rdonly, so set
1061                  * the rdonly flag and then mark the partition as valid again.
1062                  */
1063                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1064                 es->s_mtime = cpu_to_le32(get_seconds());
1065         } else {
1066                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1067                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1068                 if (ret) {
1069                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1070                                "unsupported optional features (%x).\n",
1071                                sb->s_id, le32_to_cpu(ret));
1072                         err = -EROFS;
1073                         goto restore_opts;
1074                 }
1075                 /*
1076                  * Mounting a RDONLY partition read-write, so reread and
1077                  * store the current valid flag.  (It may have been changed
1078                  * by e2fsck since we originally mounted the partition.)
1079                  */
1080                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1081                 if (!ext2_setup_super (sb, es, 0))
1082                         sb->s_flags &= ~MS_RDONLY;
1083         }
1084         ext2_sync_super(sb, es);
1085         return 0;
1086 restore_opts:
1087         sbi->s_mount_opt = old_opts.s_mount_opt;
1088         sbi->s_resuid = old_opts.s_resuid;
1089         sbi->s_resgid = old_opts.s_resgid;
1090         sb->s_flags = old_sb_flags;
1091         return err;
1092 }
1093
1094 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1095 {
1096         struct super_block *sb = dentry->d_sb;
1097         struct ext2_sb_info *sbi = EXT2_SB(sb);
1098         unsigned long overhead;
1099         int i;
1100
1101         if (test_opt (sb, MINIX_DF))
1102                 overhead = 0;
1103         else {
1104                 /*
1105                  * Compute the overhead (FS structures)
1106                  */
1107
1108                 /*
1109                  * All of the blocks before first_data_block are
1110                  * overhead
1111                  */
1112                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1113
1114                 /*
1115                  * Add the overhead attributed to the superblock and
1116                  * block group descriptors.  If the sparse superblocks
1117                  * feature is turned on, then not all groups have this.
1118                  */
1119                 for (i = 0; i < sbi->s_groups_count; i++)
1120                         overhead += ext2_bg_has_super(sb, i) +
1121                                 ext2_bg_num_gdb(sb, i);
1122
1123                 /*
1124                  * Every block group has an inode bitmap, a block
1125                  * bitmap, and an inode table.
1126                  */
1127                 overhead += (sbi->s_groups_count *
1128                              (2 + sbi->s_itb_per_group));
1129         }
1130
1131         buf->f_type = EXT2_SUPER_MAGIC;
1132         buf->f_bsize = sb->s_blocksize;
1133         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1134         buf->f_bfree = ext2_count_free_blocks(sb);
1135         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1136         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1137                 buf->f_bavail = 0;
1138         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1139         buf->f_ffree = ext2_count_free_inodes (sb);
1140         buf->f_namelen = EXT2_NAME_LEN;
1141         return 0;
1142 }
1143
1144 static int ext2_get_sb(struct file_system_type *fs_type,
1145         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1146 {
1147         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1148 }
1149
1150 #ifdef CONFIG_QUOTA
1151
1152 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1153  * acquiring the locks... As quota files are never truncated and quota code
1154  * itself serializes the operations (and noone else should touch the files)
1155  * we don't have to be afraid of races */
1156 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1157                                size_t len, loff_t off)
1158 {
1159         struct inode *inode = sb_dqopt(sb)->files[type];
1160         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1161         int err = 0;
1162         int offset = off & (sb->s_blocksize - 1);
1163         int tocopy;
1164         size_t toread;
1165         struct buffer_head tmp_bh;
1166         struct buffer_head *bh;
1167         loff_t i_size = i_size_read(inode);
1168
1169         if (off > i_size)
1170                 return 0;
1171         if (off+len > i_size)
1172                 len = i_size-off;
1173         toread = len;
1174         while (toread > 0) {
1175                 tocopy = sb->s_blocksize - offset < toread ?
1176                                 sb->s_blocksize - offset : toread;
1177
1178                 tmp_bh.b_state = 0;
1179                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1180                 if (err)
1181                         return err;
1182                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1183                         memset(data, 0, tocopy);
1184                 else {
1185                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1186                         if (!bh)
1187                                 return -EIO;
1188                         memcpy(data, bh->b_data+offset, tocopy);
1189                         brelse(bh);
1190                 }
1191                 offset = 0;
1192                 toread -= tocopy;
1193                 data += tocopy;
1194                 blk++;
1195         }
1196         return len;
1197 }
1198
1199 /* Write to quotafile */
1200 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1201                                 const char *data, size_t len, loff_t off)
1202 {
1203         struct inode *inode = sb_dqopt(sb)->files[type];
1204         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1205         int err = 0;
1206         int offset = off & (sb->s_blocksize - 1);
1207         int tocopy;
1208         size_t towrite = len;
1209         struct buffer_head tmp_bh;
1210         struct buffer_head *bh;
1211
1212         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1213         while (towrite > 0) {
1214                 tocopy = sb->s_blocksize - offset < towrite ?
1215                                 sb->s_blocksize - offset : towrite;
1216
1217                 tmp_bh.b_state = 0;
1218                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1219                 if (err)
1220                         goto out;
1221                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1222                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1223                 else
1224                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1225                 if (!bh) {
1226                         err = -EIO;
1227                         goto out;
1228                 }
1229                 lock_buffer(bh);
1230                 memcpy(bh->b_data+offset, data, tocopy);
1231                 flush_dcache_page(bh->b_page);
1232                 set_buffer_uptodate(bh);
1233                 mark_buffer_dirty(bh);
1234                 unlock_buffer(bh);
1235                 brelse(bh);
1236                 offset = 0;
1237                 towrite -= tocopy;
1238                 data += tocopy;
1239                 blk++;
1240         }
1241 out:
1242         if (len == towrite)
1243                 return err;
1244         if (inode->i_size < off+len-towrite)
1245                 i_size_write(inode, off+len-towrite);
1246         inode->i_version++;
1247         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1248         mark_inode_dirty(inode);
1249         mutex_unlock(&inode->i_mutex);
1250         return len - towrite;
1251 }
1252
1253 #endif
1254
1255 static struct file_system_type ext2_fs_type = {
1256         .owner          = THIS_MODULE,
1257         .name           = "ext2",
1258         .get_sb         = ext2_get_sb,
1259         .kill_sb        = kill_block_super,
1260         .fs_flags       = FS_REQUIRES_DEV,
1261 };
1262
1263 static int __init init_ext2_fs(void)
1264 {
1265         int err = init_ext2_xattr();
1266         if (err)
1267                 return err;
1268         err = init_inodecache();
1269         if (err)
1270                 goto out1;
1271         err = register_filesystem(&ext2_fs_type);
1272         if (err)
1273                 goto out;
1274         return 0;
1275 out:
1276         destroy_inodecache();
1277 out1:
1278         exit_ext2_xattr();
1279         return err;
1280 }
1281
1282 static void __exit exit_ext2_fs(void)
1283 {
1284         unregister_filesystem(&ext2_fs_type);
1285         destroy_inodecache();
1286         exit_ext2_xattr();
1287 }
1288
1289 module_init(init_ext2_fs)
1290 module_exit(exit_ext2_fs)