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/config.h>
  20 #include <linux/module.h>
  21 #include <linux/string.h>
  22 #include <linux/fs.h>
  23 #include <linux/slab.h>
  24 #include <linux/init.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/parser.h>
  27 #include <linux/random.h>
  28 #include <linux/buffer_head.h>
  29 #include <linux/smp_lock.h>
  30 #include <linux/vfs.h>
  31 #include <linux/seq_file.h>
  32 #include <linux/mount.h>
  33 #include <asm/uaccess.h>
  34 #include "ext2.h"
  35 #include "xattr.h"
  36 #include "acl.h"
  37 #include "xip.h"
  38
  39 static void ext2_sync_super(struct super_block *sb,
  40                             struct ext2_super_block *es);
  41 static int ext2_remount (struct super_block * sb, int * flags, char * data);
  42 static int ext2_statfs (struct super_block * sb, struct kstatfs * buf);
  43
  44 void ext2_error (struct super_block * sb, const char * function,
  45                  const char * fmt, ...)
  46 {
  47         va_list args;
  48         struct ext2_sb_info *sbi = EXT2_SB(sb);
  49         struct ext2_super_block *es = sbi->s_es;
  50
  51         if (!(sb->s_flags & MS_RDONLY)) {
  52                 sbi->s_mount_state |= EXT2_ERROR_FS;
  53                 es->s_state =
  54                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
  55                 ext2_sync_super(sb, es);
  56         }
  57
  58         va_start(args, fmt);
  59         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
  60         vprintk(fmt, args);
  61         printk("\n");
  62         va_end(args);
  63
  64         if (test_opt(sb, ERRORS_PANIC))
  65                 panic("EXT2-fs panic from previous error\n");
  66         if (test_opt(sb, ERRORS_RO)) {
  67                 printk("Remounting filesystem read-only\n");
  68                 sb->s_flags |= MS_RDONLY;
  69         }
  70 }
  71
  72 void ext2_warning (struct super_block * sb, const char * function,
  73                    const char * fmt, ...)
  74 {
  75         va_list args;
  76
  77         va_start(args, fmt);
  78         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
  79                sb->s_id, function);
  80         vprintk(fmt, args);
  81         printk("\n");
  82         va_end(args);
  83 }
  84
  85 void ext2_update_dynamic_rev(struct super_block *sb)
  86 {
  87         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
  88
  89         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
  90                 return;
  91
  92         ext2_warning(sb, __FUNCTION__,
  93                      "updating to rev %d because of new feature flag, "
  94                      "running e2fsck is recommended",
  95                      EXT2_DYNAMIC_REV);
  96
  97         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
  98         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
  99         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
 100         /* leave es->s_feature_*compat flags alone */
 101         /* es->s_uuid will be set by e2fsck if empty */
 102
 103         /*
 104          * The rest of the superblock fields should be zero, and if not it
 105          * means they are likely already in use, so leave them alone.  We
 106          * can leave it up to e2fsck to clean up any inconsistencies there.
 107          */
 108 }
 109
 110 static void ext2_put_super (struct super_block * sb)
 111 {
 112         int db_count;
 113         int i;
 114         struct ext2_sb_info *sbi = EXT2_SB(sb);
 115
 116         ext2_xattr_put_super(sb);
 117         if (!(sb->s_flags & MS_RDONLY)) {
 118                 struct ext2_super_block *es = sbi->s_es;
 119
 120                 es->s_state = cpu_to_le16(sbi->s_mount_state);
 121                 ext2_sync_super(sb, es);
 122         }
 123         db_count = sbi->s_gdb_count;
 124         for (i = 0; i < db_count; i++)
 125                 if (sbi->s_group_desc[i])
 126                         brelse (sbi->s_group_desc[i]);
 127         kfree(sbi->s_group_desc);
 128         kfree(sbi->s_debts);
 129         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 130         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 131         percpu_counter_destroy(&sbi->s_dirs_counter);
 132         brelse (sbi->s_sbh);
 133         sb->s_fs_info = NULL;
 134         kfree(sbi);
 135
 136         return;
 137 }
 138
 139 static kmem_cache_t * ext2_inode_cachep;
 140
 141 static struct inode *ext2_alloc_inode(struct super_block *sb)
 142 {
 143         struct ext2_inode_info *ei;
 144         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL);
 145         if (!ei)
 146                 return NULL;
 147 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 148         ei->i_acl = EXT2_ACL_NOT_CACHED;
 149         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 150 #endif
 151         ei->vfs_inode.i_version = 1;
 152         return &ei->vfs_inode;
 153 }
 154
 155 static void ext2_destroy_inode(struct inode *inode)
 156 {
 157         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
 158 }
 159
 160 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 161 {
 162         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
 163
 164         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 165             SLAB_CTOR_CONSTRUCTOR) {
 166                 rwlock_init(&ei->i_meta_lock);
 167 #ifdef CONFIG_EXT2_FS_XATTR
 168                 init_rwsem(&ei->xattr_sem);
 169 #endif
 170                 inode_init_once(&ei->vfs_inode);
 171         }
 172 }
 173
 174 static int init_inodecache(void)
 175 {
 176         ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
 177                                              sizeof(struct ext2_inode_info),
 178                                              0, SLAB_RECLAIM_ACCOUNT,
 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         else
 214                 seq_puts(seq, ",nogrpid");
 215
 216 #if defined(CONFIG_QUOTA)
 217         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
 218                 seq_puts(seq, ",usrquota");
 219
 220         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
 221                 seq_puts(seq, ",grpquota");
 222 #endif
 223
 224 #if defined(CONFIG_EXT2_FS_XIP)
 225         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
 226                 seq_puts(seq, ",xip");
 227 #endif
 228
 229         return 0;
 230 }
 231
 232 #ifdef CONFIG_QUOTA
 233 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
 234 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
 235 #endif
 236
 237 static struct super_operations ext2_sops = {
 238         .alloc_inode    = ext2_alloc_inode,
 239         .destroy_inode  = ext2_destroy_inode,
 240         .read_inode     = ext2_read_inode,
 241         .write_inode    = ext2_write_inode,
 242         .put_inode      = ext2_put_inode,
 243         .delete_inode   = ext2_delete_inode,
 244         .put_super      = ext2_put_super,
 245         .write_super    = ext2_write_super,
 246         .statfs         = ext2_statfs,
 247         .remount_fs     = ext2_remount,
 248         .clear_inode    = ext2_clear_inode,
 249         .show_options   = ext2_show_options,
 250 #ifdef CONFIG_QUOTA
 251         .quota_read     = ext2_quota_read,
 252         .quota_write    = ext2_quota_write,
 253 #endif
 254 };
 255
 256 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
 257 {
 258         __u32 *objp = vobjp;
 259         unsigned long ino = objp[0];
 260         __u32 generation = objp[1];
 261         struct inode *inode;
 262         struct dentry *result;
 263
 264         if (ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb))
 265                 return ERR_PTR(-ESTALE);
 266         if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
 267                 return ERR_PTR(-ESTALE);
 268
 269         /* iget isn't really right if the inode is currently unallocated!!
 270          * ext2_read_inode currently does appropriate checks, but
 271          * it might be "neater" to call ext2_get_inode first and check
 272          * if the inode is valid.....
 273          */
 274         inode = iget(sb, ino);
 275         if (inode == NULL)
 276                 return ERR_PTR(-ENOMEM);
 277         if (is_bad_inode(inode)
 278             || (generation && inode->i_generation != generation)
 279                 ) {
 280                 /* we didn't find the right inode.. */
 281                 iput(inode);
 282                 return ERR_PTR(-ESTALE);
 283         }
 284         /* now to find a dentry.
 285          * If possible, get a well-connected one
 286          */
 287         result = d_alloc_anon(inode);
 288         if (!result) {
 289                 iput(inode);
 290                 return ERR_PTR(-ENOMEM);
 291         }
 292         return result;
 293 }
 294
 295
 296 /* Yes, most of these are left as NULL!!
 297  * A NULL value implies the default, which works with ext2-like file
 298  * systems, but can be improved upon.
 299  * Currently only get_parent is required.
 300  */
 301 struct dentry *ext2_get_parent(struct dentry *child);
 302 static struct export_operations ext2_export_ops = {
 303         .get_parent = ext2_get_parent,
 304         .get_dentry = ext2_get_dentry,
 305 };
 306
 307 static unsigned long get_sb_block(void **data)
 308 {
 309         unsigned long   sb_block;
 310         char            *options = (char *) *data;
 311
 312         if (!options || strncmp(options, "sb=", 3) != 0)
 313                 return 1;       /* Default location */
 314         options += 3;
 315         sb_block = simple_strtoul(options, &options, 0);
 316         if (*options && *options != ',') {
 317                 printk("EXT2-fs: Invalid sb specification: %s\n",
 318                        (char *) *data);
 319                 return 1;
 320         }
 321         if (*options == ',')
 322                 options++;
 323         *data = (void *) options;
 324         return sb_block;
 325 }
 326
 327 enum {
 328         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 329         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
 330         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
 331         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
 332         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
 333         Opt_usrquota, Opt_grpquota, Opt_tagxid
 334 };
 335
 336 static match_table_t tokens = {
 337         {Opt_bsd_df, "bsddf"},
 338         {Opt_minix_df, "minixdf"},
 339         {Opt_grpid, "grpid"},
 340         {Opt_grpid, "bsdgroups"},
 341         {Opt_nogrpid, "nogrpid"},
 342         {Opt_nogrpid, "sysvgroups"},
 343         {Opt_resgid, "resgid=%u"},
 344         {Opt_resuid, "resuid=%u"},
 345         {Opt_sb, "sb=%u"},
 346         {Opt_err_cont, "errors=continue"},
 347         {Opt_err_panic, "errors=panic"},
 348         {Opt_err_ro, "errors=remount-ro"},
 349         {Opt_nouid32, "nouid32"},
 350         {Opt_nocheck, "check=none"},
 351         {Opt_nocheck, "nocheck"},
 352         {Opt_debug, "debug"},
 353         {Opt_oldalloc, "oldalloc"},
 354         {Opt_orlov, "orlov"},
 355         {Opt_nobh, "nobh"},
 356         {Opt_user_xattr, "user_xattr"},
 357         {Opt_nouser_xattr, "nouser_xattr"},
 358         {Opt_acl, "acl"},
 359         {Opt_noacl, "noacl"},
 360         {Opt_xip, "xip"},
 361         {Opt_tagxid, "tagxid"},
 362         {Opt_grpquota, "grpquota"},
 363         {Opt_ignore, "noquota"},
 364         {Opt_quota, "quota"},
 365         {Opt_usrquota, "usrquota"},
 366         {Opt_err, NULL}
 367 };
 368
 369 static int parse_options (char * options,
 370                           struct ext2_sb_info *sbi)
 371 {
 372         char * p;
 373         substring_t args[MAX_OPT_ARGS];
 374         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 375         int option;
 376
 377         if (!options)
 378                 return 1;
 379
 380         while ((p = strsep (&options, ",")) != NULL) {
 381                 int token;
 382                 if (!*p)
 383                         continue;
 384
 385                 token = match_token(p, tokens, args);
 386                 switch (token) {
 387                 case Opt_bsd_df:
 388                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 389                         break;
 390                 case Opt_minix_df:
 391                         set_opt (sbi->s_mount_opt, MINIX_DF);
 392                         break;
 393                 case Opt_grpid:
 394                         set_opt (sbi->s_mount_opt, GRPID);
 395                         break;
 396                 case Opt_nogrpid:
 397                         clear_opt (sbi->s_mount_opt, GRPID);
 398                         break;
 399                 case Opt_resuid:
 400                         if (match_int(&args[0], &option))
 401                                 return 0;
 402                         sbi->s_resuid = option;
 403                         break;
 404                 case Opt_resgid:
 405                         if (match_int(&args[0], &option))
 406                                 return 0;
 407                         sbi->s_resgid = option;
 408                         break;
 409                 case Opt_sb:
 410                         /* handled by get_sb_block() instead of here */
 411                         /* *sb_block = match_int(&args[0]); */
 412                         break;
 413                 case Opt_err_panic:
 414                         kind = EXT2_MOUNT_ERRORS_PANIC;
 415                         break;
 416                 case Opt_err_ro:
 417                         kind = EXT2_MOUNT_ERRORS_RO;
 418                         break;
 419                 case Opt_err_cont:
 420                         kind = EXT2_MOUNT_ERRORS_CONT;
 421                         break;
 422                 case Opt_nouid32:
 423                         set_opt (sbi->s_mount_opt, NO_UID32);
 424                         break;
 425 #ifndef CONFIG_INOXID_NONE
 426                 case Opt_tagxid:
 427                         set_opt (sbi->s_mount_opt, TAGXID);
 428                         break;
 429 #endif
 430                 case Opt_nocheck:
 431                         clear_opt (sbi->s_mount_opt, CHECK);
 432                         break;
 433                 case Opt_debug:
 434                         set_opt (sbi->s_mount_opt, DEBUG);
 435                         break;
 436                 case Opt_oldalloc:
 437                         set_opt (sbi->s_mount_opt, OLDALLOC);
 438                         break;
 439                 case Opt_orlov:
 440                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 441                         break;
 442                 case Opt_nobh:
 443                         set_opt (sbi->s_mount_opt, NOBH);
 444                         break;
 445 #ifdef CONFIG_EXT2_FS_XATTR
 446                 case Opt_user_xattr:
 447                         set_opt (sbi->s_mount_opt, XATTR_USER);
 448                         break;
 449                 case Opt_nouser_xattr:
 450                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 451                         break;
 452 #else
 453                 case Opt_user_xattr:
 454                 case Opt_nouser_xattr:
 455                         printk("EXT2 (no)user_xattr options not supported\n");
 456                         break;
 457 #endif
 458 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 459                 case Opt_acl:
 460                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 461                         break;
 462                 case Opt_noacl:
 463                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 464                         break;
 465 #else
 466                 case Opt_acl:
 467                 case Opt_noacl:
 468                         printk("EXT2 (no)acl options not supported\n");
 469                         break;
 470 #endif
 471                 case Opt_xip:
 472 #ifdef CONFIG_EXT2_FS_XIP
 473                         set_opt (sbi->s_mount_opt, XIP);
 474 #else
 475                         printk("EXT2 xip option not supported\n");
 476 #endif
 477                         break;
 478
 479 #if defined(CONFIG_QUOTA)
 480                 case Opt_quota:
 481                 case Opt_usrquota:
 482                         set_opt(sbi->s_mount_opt, USRQUOTA);
 483                         break;
 484
 485                 case Opt_grpquota:
 486                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 487                         break;
 488 #else
 489                 case Opt_quota:
 490                 case Opt_usrquota:
 491                 case Opt_grpquota:
 492                         printk(KERN_ERR
 493                                 "EXT2-fs: quota operations not supported.\n");
 494
 495                         break;
 496 #endif
 497
 498                 case Opt_ignore:
 499                         break;
 500                 default:
 501                         return 0;
 502                 }
 503         }
 504         sbi->s_mount_opt |= kind;
 505         return 1;
 506 }
 507
 508 static int ext2_setup_super (struct super_block * sb,
 509                               struct ext2_super_block * es,
 510                               int read_only)
 511 {
 512         int res = 0;
 513         struct ext2_sb_info *sbi = EXT2_SB(sb);
 514
 515         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 516                 printk ("EXT2-fs warning: revision level too high, "
 517                         "forcing read-only mode\n");
 518                 res = MS_RDONLY;
 519         }
 520         if (read_only)
 521                 return res;
 522         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 523                 printk ("EXT2-fs warning: mounting unchecked fs, "
 524                         "running e2fsck is recommended\n");
 525         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 526                 printk ("EXT2-fs warning: mounting fs with errors, "
 527                         "running e2fsck is recommended\n");
 528         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 529                  le16_to_cpu(es->s_mnt_count) >=
 530                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 531                 printk ("EXT2-fs warning: maximal mount count reached, "
 532                         "running e2fsck is recommended\n");
 533         else if (le32_to_cpu(es->s_checkinterval) &&
 534                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 535                 printk ("EXT2-fs warning: checktime reached, "
 536                         "running e2fsck is recommended\n");
 537         if (!le16_to_cpu(es->s_max_mnt_count))
 538                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 539         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 540         ext2_write_super(sb);
 541         if (test_opt (sb, DEBUG))
 542                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 543                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 544                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 545                         sbi->s_frag_size,
 546                         sbi->s_groups_count,
 547                         EXT2_BLOCKS_PER_GROUP(sb),
 548                         EXT2_INODES_PER_GROUP(sb),
 549                         sbi->s_mount_opt);
 550         return res;
 551 }
 552
 553 static int ext2_check_descriptors (struct super_block * sb)
 554 {
 555         int i;
 556         int desc_block = 0;
 557         struct ext2_sb_info *sbi = EXT2_SB(sb);
 558         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
 559         struct ext2_group_desc * gdp = NULL;
 560
 561         ext2_debug ("Checking group descriptors");
 562
 563         for (i = 0; i < sbi->s_groups_count; i++)
 564         {
 565                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 566                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 567                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
 568                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 569                 {
 570                         ext2_error (sb, "ext2_check_descriptors",
 571                                     "Block bitmap for group %d"
 572                                     " not in group (block %lu)!",
 573                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 574                         return 0;
 575                 }
 576                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
 577                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 578                 {
 579                         ext2_error (sb, "ext2_check_descriptors",
 580                                     "Inode bitmap for group %d"
 581                                     " not in group (block %lu)!",
 582                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 583                         return 0;
 584                 }
 585                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
 586                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
 587                     block + EXT2_BLOCKS_PER_GROUP(sb))
 588                 {
 589                         ext2_error (sb, "ext2_check_descriptors",
 590                                     "Inode table for group %d"
 591                                     " not in group (block %lu)!",
 592                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 593                         return 0;
 594                 }
 595                 block += EXT2_BLOCKS_PER_GROUP(sb);
 596                 gdp++;
 597         }
 598         return 1;
 599 }
 600
 601 #define log2(n) ffz(~(n))
 602
 603 /*
 604  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 605  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 606  * We need to be 1 filesystem block less than the 2^32 sector limit.
 607  */
 608 static loff_t ext2_max_size(int bits)
 609 {
 610         loff_t res = EXT2_NDIR_BLOCKS;
 611         /* This constant is calculated to be the largest file size for a
 612          * dense, 4k-blocksize file such that the total number of
 613          * sectors in the file, including data and all indirect blocks,
 614          * does not exceed 2^32. */
 615         const loff_t upper_limit = 0x1ff7fffd000LL;
 616
 617         res += 1LL << (bits-2);
 618         res += 1LL << (2*(bits-2));
 619         res += 1LL << (3*(bits-2));
 620         res <<= bits;
 621         if (res > upper_limit)
 622                 res = upper_limit;
 623         return res;
 624 }
 625
 626 static unsigned long descriptor_loc(struct super_block *sb,
 627                                     unsigned long logic_sb_block,
 628                                     int nr)
 629 {
 630         struct ext2_sb_info *sbi = EXT2_SB(sb);
 631         unsigned long bg, first_data_block, first_meta_bg;
 632         int has_super = 0;
 633
 634         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 635         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 636
 637         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 638             nr < first_meta_bg)
 639                 return (logic_sb_block + nr + 1);
 640         bg = sbi->s_desc_per_block * nr;
 641         if (ext2_bg_has_super(sb, bg))
 642                 has_super = 1;
 643         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 644 }
 645
 646 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 647 {
 648         struct buffer_head * bh;
 649         struct ext2_sb_info * sbi;
 650         struct ext2_super_block * es;
 651         struct inode *root;
 652         unsigned long block;
 653         unsigned long sb_block = get_sb_block(&data);
 654         unsigned long logic_sb_block;
 655         unsigned long offset = 0;
 656         unsigned long def_mount_opts;
 657         int blocksize = BLOCK_SIZE;
 658         int db_count;
 659         int i, j;
 660         __le32 features;
 661
 662         sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
 663         if (!sbi)
 664                 return -ENOMEM;
 665         sb->s_fs_info = sbi;
 666         memset(sbi, 0, sizeof(*sbi));
 667
 668         /*
 669          * See what the current blocksize for the device is, and
 670          * use that as the blocksize.  Otherwise (or if the blocksize
 671          * is smaller than the default) use the default.
 672          * This is important for devices that have a hardware
 673          * sectorsize that is larger than the default.
 674          */
 675         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 676         if (!blocksize) {
 677                 printk ("EXT2-fs: unable to set blocksize\n");
 678                 goto failed_sbi;
 679         }
 680
 681         /*
 682          * If the superblock doesn't start on a hardware sector boundary,
 683          * calculate the offset.
 684          */
 685         if (blocksize != BLOCK_SIZE) {
 686                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 687                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 688         } else {
 689                 logic_sb_block = sb_block;
 690         }
 691
 692         if (!(bh = sb_bread(sb, logic_sb_block))) {
 693                 printk ("EXT2-fs: unable to read superblock\n");
 694                 goto failed_sbi;
 695         }
 696         /*
 697          * Note: s_es must be initialized as soon as possible because
 698          *       some ext2 macro-instructions depend on its value
 699          */
 700         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 701         sbi->s_es = es;
 702         sb->s_magic = le16_to_cpu(es->s_magic);
 703
 704         if (sb->s_magic != EXT2_SUPER_MAGIC)
 705                 goto cantfind_ext2;
 706
 707         /* Set defaults before we parse the mount options */
 708         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 709         if (def_mount_opts & EXT2_DEFM_DEBUG)
 710                 set_opt(sbi->s_mount_opt, DEBUG);
 711         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 712                 set_opt(sbi->s_mount_opt, GRPID);
 713         if (def_mount_opts & EXT2_DEFM_UID16)
 714                 set_opt(sbi->s_mount_opt, NO_UID32);
 715         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 716                 set_opt(sbi->s_mount_opt, XATTR_USER);
 717         if (def_mount_opts & EXT2_DEFM_ACL)
 718                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 719
 720         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 721                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 722         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 723                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 724
 725         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 726         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 727
 728         if (!parse_options ((char *) data, sbi))
 729                 goto failed_mount;
 730
 731         if (EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_TAGXID)
 732                 sb->s_flags |= MS_TAGXID;
 733         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 734                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 735                  MS_POSIXACL : 0);
 736
 737         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 738                                     EXT2_MOUNT_XIP if not */
 739
 740         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 741             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 742              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 743              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 744                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 745                        "running e2fsck is recommended\n");
 746         /*
 747          * Check feature flags regardless of the revision level, since we
 748          * previously didn't change the revision level when setting the flags,
 749          * so there is a chance incompat flags are set on a rev 0 filesystem.
 750          */
 751         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 752         if (features) {
 753                 printk("EXT2-fs: %s: couldn't mount because of "
 754                        "unsupported optional features (%x).\n",
 755                        sb->s_id, le32_to_cpu(features));
 756                 goto failed_mount;
 757         }
 758         if (!(sb->s_flags & MS_RDONLY) &&
 759             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 760                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 761                        "unsupported optional features (%x).\n",
 762                        sb->s_id, le32_to_cpu(features));
 763                 goto failed_mount;
 764         }
 765
 766         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 767
 768         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 769                                   (sb->s_blocksize != blocksize))) {
 770                 if (!silent)
 771                         printk("XIP: Unsupported blocksize\n");
 772                 goto failed_mount;
 773         }
 774
 775         /* If the blocksize doesn't match, re-read the thing.. */
 776         if (sb->s_blocksize != blocksize) {
 777                 brelse(bh);
 778
 779                 if (!sb_set_blocksize(sb, blocksize)) {
 780                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 781                         goto failed_sbi;
 782                 }
 783
 784                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 785                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 786                 bh = sb_bread(sb, logic_sb_block);
 787                 if(!bh) {
 788                         printk("EXT2-fs: Couldn't read superblock on "
 789                                "2nd try.\n");
 790                         goto failed_sbi;
 791                 }
 792                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 793                 sbi->s_es = es;
 794                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 795                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 796                         goto failed_mount;
 797                 }
 798         }
 799
 800         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 801
 802         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 803                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 804                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 805         } else {
 806                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 807                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 808                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 809                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 810                     (sbi->s_inode_size > blocksize)) {
 811                         printk ("EXT2-fs: unsupported inode size: %d\n",
 812                                 sbi->s_inode_size);
 813                         goto failed_mount;
 814                 }
 815         }
 816
 817         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 818                                    le32_to_cpu(es->s_log_frag_size);
 819         if (sbi->s_frag_size == 0)
 820                 goto cantfind_ext2;
 821         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 822
 823         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 824         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 825         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 826
 827         if (EXT2_INODE_SIZE(sb) == 0)
 828                 goto cantfind_ext2;
 829         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 830         if (sbi->s_inodes_per_block == 0)
 831                 goto cantfind_ext2;
 832         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 833                                         sbi->s_inodes_per_block;
 834         sbi->s_desc_per_block = sb->s_blocksize /
 835                                         sizeof (struct ext2_group_desc);
 836         sbi->s_sbh = bh;
 837         sbi->s_mount_state = le16_to_cpu(es->s_state);
 838         sbi->s_addr_per_block_bits =
 839                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 840         sbi->s_desc_per_block_bits =
 841                 log2 (EXT2_DESC_PER_BLOCK(sb));
 842
 843         if (sb->s_magic != EXT2_SUPER_MAGIC)
 844                 goto cantfind_ext2;
 845
 846         if (sb->s_blocksize != bh->b_size) {
 847                 if (!silent)
 848                         printk ("VFS: Unsupported blocksize on dev "
 849                                 "%s.\n", sb->s_id);
 850                 goto failed_mount;
 851         }
 852
 853         if (sb->s_blocksize != sbi->s_frag_size) {
 854                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 855                         sbi->s_frag_size, sb->s_blocksize);
 856                 goto failed_mount;
 857         }
 858
 859         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 860                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 861                         sbi->s_blocks_per_group);
 862                 goto failed_mount;
 863         }
 864         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 865                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 866                         sbi->s_frags_per_group);
 867                 goto failed_mount;
 868         }
 869         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 870                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 871                         sbi->s_inodes_per_group);
 872                 goto failed_mount;
 873         }
 874
 875         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 876                 goto cantfind_ext2;
 877         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
 878                                         le32_to_cpu(es->s_first_data_block) +
 879                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 880                                        EXT2_BLOCKS_PER_GROUP(sb);
 881         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 882                    EXT2_DESC_PER_BLOCK(sb);
 883         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 884         if (sbi->s_group_desc == NULL) {
 885                 printk ("EXT2-fs: not enough memory\n");
 886                 goto failed_mount;
 887         }
 888         percpu_counter_init(&sbi->s_freeblocks_counter);
 889         percpu_counter_init(&sbi->s_freeinodes_counter);
 890         percpu_counter_init(&sbi->s_dirs_counter);
 891         bgl_lock_init(&sbi->s_blockgroup_lock);
 892         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 893                                GFP_KERNEL);
 894         if (!sbi->s_debts) {
 895                 printk ("EXT2-fs: not enough memory\n");
 896                 goto failed_mount_group_desc;
 897         }
 898         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 899         for (i = 0; i < db_count; i++) {
 900                 block = descriptor_loc(sb, logic_sb_block, i);
 901                 sbi->s_group_desc[i] = sb_bread(sb, block);
 902                 if (!sbi->s_group_desc[i]) {
 903                         for (j = 0; j < i; j++)
 904                                 brelse (sbi->s_group_desc[j]);
 905                         printk ("EXT2-fs: unable to read group descriptors\n");
 906                         goto failed_mount_group_desc;
 907                 }
 908         }
 909         if (!ext2_check_descriptors (sb)) {
 910                 printk ("EXT2-fs: group descriptors corrupted!\n");
 911                 db_count = i;
 912                 goto failed_mount2;
 913         }
 914         sbi->s_gdb_count = db_count;
 915         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 916         spin_lock_init(&sbi->s_next_gen_lock);
 917         /*
 918          * set up enough so that it can read an inode
 919          */
 920         sb->s_op = &ext2_sops;
 921         sb->s_export_op = &ext2_export_ops;
 922         sb->s_xattr = ext2_xattr_handlers;
 923         root = iget(sb, EXT2_ROOT_INO);
 924         sb->s_root = d_alloc_root(root);
 925         if (!sb->s_root) {
 926                 iput(root);
 927                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 928                 goto failed_mount2;
 929         }
 930         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 931                 dput(sb->s_root);
 932                 sb->s_root = NULL;
 933                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 934                 goto failed_mount2;
 935         }
 936         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 937                 ext2_warning(sb, __FUNCTION__,
 938                         "mounting ext3 filesystem as ext2");
 939         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 940         percpu_counter_mod(&sbi->s_freeblocks_counter,
 941                                 ext2_count_free_blocks(sb));
 942         percpu_counter_mod(&sbi->s_freeinodes_counter,
 943                                 ext2_count_free_inodes(sb));
 944         percpu_counter_mod(&sbi->s_dirs_counter,
 945                                 ext2_count_dirs(sb));
 946         return 0;
 947
 948 cantfind_ext2:
 949         if (!silent)
 950                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 951                        sb->s_id);
 952         goto failed_mount;
 953
 954 failed_mount2:
 955         for (i = 0; i < db_count; i++)
 956                 brelse(sbi->s_group_desc[i]);
 957 failed_mount_group_desc:
 958         kfree(sbi->s_group_desc);
 959         kfree(sbi->s_debts);
 960 failed_mount:
 961         brelse(bh);
 962 failed_sbi:
 963         sb->s_fs_info = NULL;
 964         kfree(sbi);
 965         return -EINVAL;
 966 }
 967
 968 static void ext2_commit_super (struct super_block * sb,
 969                                struct ext2_super_block * es)
 970 {
 971         es->s_wtime = cpu_to_le32(get_seconds());
 972         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 973         sb->s_dirt = 0;
 974 }
 975
 976 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 977 {
 978         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 979         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 980         es->s_wtime = cpu_to_le32(get_seconds());
 981         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 982         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 983         sb->s_dirt = 0;
 984 }
 985
 986 /*
 987  * In the second extended file system, it is not necessary to
 988  * write the super block since we use a mapping of the
 989  * disk super block in a buffer.
 990  *
 991  * However, this function is still used to set the fs valid
 992  * flags to 0.  We need to set this flag to 0 since the fs
 993  * may have been checked while mounted and e2fsck may have
 994  * set s_state to EXT2_VALID_FS after some corrections.
 995  */
 996
 997 void ext2_write_super (struct super_block * sb)
 998 {
 999         struct ext2_super_block * es;
1000         lock_kernel();
1001         if (!(sb->s_flags & MS_RDONLY)) {
1002                 es = EXT2_SB(sb)->s_es;
1003
1004                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1005                         ext2_debug ("setting valid to 0\n");
1006                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1007                                                   ~EXT2_VALID_FS);
1008                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1009                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1010                         es->s_mtime = cpu_to_le32(get_seconds());
1011                         ext2_sync_super(sb, es);
1012                 } else
1013                         ext2_commit_super (sb, es);
1014         }
1015         sb->s_dirt = 0;
1016         unlock_kernel();
1017 }
1018
1019 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1020 {
1021         struct ext2_sb_info * sbi = EXT2_SB(sb);
1022         struct ext2_super_block * es;
1023         unsigned long old_mount_opt = sbi->s_mount_opt;
1024         struct ext2_mount_options old_opts;
1025         unsigned long old_sb_flags;
1026         int err;
1027
1028         /* Store the old options */
1029         old_sb_flags = sb->s_flags;
1030         old_opts.s_mount_opt = sbi->s_mount_opt;
1031         old_opts.s_resuid = sbi->s_resuid;
1032         old_opts.s_resgid = sbi->s_resgid;
1033
1034         /*
1035          * Allow the "check" option to be passed as a remount option.
1036          */
1037         if (!parse_options (data, sbi)) {
1038                 err = -EINVAL;
1039                 goto restore_opts;
1040         }
1041
1042         if ((sbi->s_mount_opt & EXT2_MOUNT_TAGXID) &&
1043                 !(sb->s_flags & MS_TAGXID)) {
1044                 printk("EXT2-fs: %s: tagxid not permitted on remount.\n",
1045                        sb->s_id);
1046                 return -EINVAL;
1047         }
1048
1049         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1050                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1051
1052         es = sbi->s_es;
1053         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1054             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1055             invalidate_inodes(sb))
1056                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1057                              "xip remain in cache (no functional problem)");
1058         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1059                 return 0;
1060         if (*flags & MS_RDONLY) {
1061                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1062                     !(sbi->s_mount_state & EXT2_VALID_FS))
1063                         return 0;
1064                 /*
1065                  * OK, we are remounting a valid rw partition rdonly, so set
1066                  * the rdonly flag and then mark the partition as valid again.
1067                  */
1068                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1069                 es->s_mtime = cpu_to_le32(get_seconds());
1070         } else {
1071                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1072                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1073                 if (ret) {
1074                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1075                                "unsupported optional features (%x).\n",
1076                                sb->s_id, le32_to_cpu(ret));
1077                         err = -EROFS;
1078                         goto restore_opts;
1079                 }
1080                 /*
1081                  * Mounting a RDONLY partition read-write, so reread and
1082                  * store the current valid flag.  (It may have been changed
1083                  * by e2fsck since we originally mounted the partition.)
1084                  */
1085                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1086                 if (!ext2_setup_super (sb, es, 0))
1087                         sb->s_flags &= ~MS_RDONLY;
1088         }
1089         ext2_sync_super(sb, es);
1090         return 0;
1091 restore_opts:
1092         sbi->s_mount_opt = old_opts.s_mount_opt;
1093         sbi->s_resuid = old_opts.s_resuid;
1094         sbi->s_resgid = old_opts.s_resgid;
1095         sb->s_flags = old_sb_flags;
1096         return err;
1097 }
1098
1099 static int ext2_statfs (struct super_block * sb, struct kstatfs * buf)
1100 {
1101         struct ext2_sb_info *sbi = EXT2_SB(sb);
1102         unsigned long overhead;
1103         int i;
1104
1105         if (test_opt (sb, MINIX_DF))
1106                 overhead = 0;
1107         else {
1108                 /*
1109                  * Compute the overhead (FS structures)
1110                  */
1111
1112                 /*
1113                  * All of the blocks before first_data_block are
1114                  * overhead
1115                  */
1116                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1117
1118                 /*
1119                  * Add the overhead attributed to the superblock and
1120                  * block group descriptors.  If the sparse superblocks
1121                  * feature is turned on, then not all groups have this.
1122                  */
1123                 for (i = 0; i < sbi->s_groups_count; i++)
1124                         overhead += ext2_bg_has_super(sb, i) +
1125                                 ext2_bg_num_gdb(sb, i);
1126
1127                 /*
1128                  * Every block group has an inode bitmap, a block
1129                  * bitmap, and an inode table.
1130                  */
1131                 overhead += (sbi->s_groups_count *
1132                              (2 + sbi->s_itb_per_group));
1133         }
1134
1135         buf->f_type = EXT2_SUPER_MAGIC;
1136         buf->f_bsize = sb->s_blocksize;
1137         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1138         buf->f_bfree = ext2_count_free_blocks(sb);
1139         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1140         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1141                 buf->f_bavail = 0;
1142         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1143         buf->f_ffree = ext2_count_free_inodes (sb);
1144         buf->f_namelen = EXT2_NAME_LEN;
1145         return 0;
1146 }
1147
1148 static struct super_block *ext2_get_sb(struct file_system_type *fs_type,
1149         int flags, const char *dev_name, void *data)
1150 {
1151         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super);
1152 }
1153
1154 #ifdef CONFIG_QUOTA
1155
1156 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1157  * acquiring the locks... As quota files are never truncated and quota code
1158  * itself serializes the operations (and noone else should touch the files)
1159  * we don't have to be afraid of races */
1160 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1161                                size_t len, loff_t off)
1162 {
1163         struct inode *inode = sb_dqopt(sb)->files[type];
1164         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1165         int err = 0;
1166         int offset = off & (sb->s_blocksize - 1);
1167         int tocopy;
1168         size_t toread;
1169         struct buffer_head tmp_bh;
1170         struct buffer_head *bh;
1171         loff_t i_size = i_size_read(inode);
1172
1173         if (off > i_size)
1174                 return 0;
1175         if (off+len > i_size)
1176                 len = i_size-off;
1177         toread = len;
1178         while (toread > 0) {
1179                 tocopy = sb->s_blocksize - offset < toread ?
1180                                 sb->s_blocksize - offset : toread;
1181
1182                 tmp_bh.b_state = 0;
1183                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1184                 if (err)
1185                         return err;
1186                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1187                         memset(data, 0, tocopy);
1188                 else {
1189                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1190                         if (!bh)
1191                                 return -EIO;
1192                         memcpy(data, bh->b_data+offset, tocopy);
1193                         brelse(bh);
1194                 }
1195                 offset = 0;
1196                 toread -= tocopy;
1197                 data += tocopy;
1198                 blk++;
1199         }
1200         return len;
1201 }
1202
1203 /* Write to quotafile */
1204 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1205                                 const char *data, size_t len, loff_t off)
1206 {
1207         struct inode *inode = sb_dqopt(sb)->files[type];
1208         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1209         int err = 0;
1210         int offset = off & (sb->s_blocksize - 1);
1211         int tocopy;
1212         size_t towrite = len;
1213         struct buffer_head tmp_bh;
1214         struct buffer_head *bh;
1215
1216         mutex_lock(&inode->i_mutex);
1217         while (towrite > 0) {
1218                 tocopy = sb->s_blocksize - offset < towrite ?
1219                                 sb->s_blocksize - offset : towrite;
1220
1221                 tmp_bh.b_state = 0;
1222                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1223                 if (err)
1224                         goto out;
1225                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1226                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1227                 else
1228                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1229                 if (!bh) {
1230                         err = -EIO;
1231                         goto out;
1232                 }
1233                 lock_buffer(bh);
1234                 memcpy(bh->b_data+offset, data, tocopy);
1235                 flush_dcache_page(bh->b_page);
1236                 set_buffer_uptodate(bh);
1237                 mark_buffer_dirty(bh);
1238                 unlock_buffer(bh);
1239                 brelse(bh);
1240                 offset = 0;
1241                 towrite -= tocopy;
1242                 data += tocopy;
1243                 blk++;
1244         }
1245 out:
1246         if (len == towrite)
1247                 return err;
1248         if (inode->i_size < off+len-towrite)
1249                 i_size_write(inode, off+len-towrite);
1250         inode->i_version++;
1251         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1252         mark_inode_dirty(inode);
1253         mutex_unlock(&inode->i_mutex);
1254         return len - towrite;
1255 }
1256
1257 #endif
1258
1259 static struct file_system_type ext2_fs_type = {
1260         .owner          = THIS_MODULE,
1261         .name           = "ext2",
1262         .get_sb         = ext2_get_sb,
1263         .kill_sb        = kill_block_super,
1264         .fs_flags       = FS_REQUIRES_DEV,
1265 };
1266
1267 static int __init init_ext2_fs(void)
1268 {
1269         int err = init_ext2_xattr();
1270         if (err)
1271                 return err;
1272         err = init_inodecache();
1273         if (err)
1274                 goto out1;
1275         err = register_filesystem(&ext2_fs_type);
1276         if (err)
1277                 goto out;
1278         return 0;
1279 out:
1280         destroy_inodecache();
1281 out1:
1282         exit_ext2_xattr();
1283         return err;
1284 }
1285
1286 static void __exit exit_ext2_fs(void)
1287 {
1288         unregister_filesystem(&ext2_fs_type);
1289         destroy_inodecache();
1290         exit_ext2_xattr();
1291 }
1292
1293 module_init(init_ext2_fs)
1294 module_exit(exit_ext2_fs)