fs/ext2/super.c

   1 /*
   2  *  linux/fs/ext2/super.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/inode.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  Big-endian to little-endian byte-swapping/bitmaps by
  16  *        David S. Miller (davem@caip.rutgers.edu), 1995
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/string.h>
  21 #include <linux/fs.h>
  22 #include <linux/slab.h>
  23 #include <linux/init.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/parser.h>
  26 #include <linux/random.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/vfs.h>
  30 #include <linux/seq_file.h>
  31 #include <linux/mount.h>
  32 #include <asm/uaccess.h>
  33 #include "ext2.h"
  34 #include "xattr.h"
  35 #include "acl.h"
  36 #include "xip.h"
  37
  38 static void ext2_sync_super(struct super_block *sb,
  39                             struct ext2_super_block *es);
  40 static int ext2_remount (struct super_block * sb, int * flags, char * data);
  41 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
  42
  43 void ext2_error (struct super_block * sb, const char * function,
  44                  const char * fmt, ...)
  45 {
  46         va_list args;
  47         struct ext2_sb_info *sbi = EXT2_SB(sb);
  48         struct ext2_super_block *es = sbi->s_es;
  49
  50         if (!(sb->s_flags & MS_RDONLY)) {
  51                 sbi->s_mount_state |= EXT2_ERROR_FS;
  52                 es->s_state =
  53                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
  54                 ext2_sync_super(sb, es);
  55         }
  56
  57         va_start(args, fmt);
  58         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
  59         vprintk(fmt, args);
  60         printk("\n");
  61         va_end(args);
  62
  63         if (test_opt(sb, ERRORS_PANIC))
  64                 panic("EXT2-fs panic from previous error\n");
  65         if (test_opt(sb, ERRORS_RO)) {
  66                 printk("Remounting filesystem read-only\n");
  67                 sb->s_flags |= MS_RDONLY;
  68         }
  69 }
  70
  71 void ext2_warning (struct super_block * sb, const char * function,
  72                    const char * fmt, ...)
  73 {
  74         va_list args;
  75
  76         va_start(args, fmt);
  77         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
  78                sb->s_id, function);
  79         vprintk(fmt, args);
  80         printk("\n");
  81         va_end(args);
  82 }
  83
  84 void ext2_update_dynamic_rev(struct super_block *sb)
  85 {
  86         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
  87
  88         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
  89                 return;
  90
  91         ext2_warning(sb, __FUNCTION__,
  92                      "updating to rev %d because of new feature flag, "
  93                      "running e2fsck is recommended",
  94                      EXT2_DYNAMIC_REV);
  95
  96         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
  97         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
  98         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
  99         /* leave es->s_feature_*compat flags alone */
 100         /* es->s_uuid will be set by e2fsck if empty */
 101
 102         /*
 103          * The rest of the superblock fields should be zero, and if not it
 104          * means they are likely already in use, so leave them alone.  We
 105          * can leave it up to e2fsck to clean up any inconsistencies there.
 106          */
 107 }
 108
 109 static void ext2_put_super (struct super_block * sb)
 110 {
 111         int db_count;
 112         int i;
 113         struct ext2_sb_info *sbi = EXT2_SB(sb);
 114
 115         ext2_xattr_put_super(sb);
 116         if (!(sb->s_flags & MS_RDONLY)) {
 117                 struct ext2_super_block *es = sbi->s_es;
 118
 119                 es->s_state = cpu_to_le16(sbi->s_mount_state);
 120                 ext2_sync_super(sb, es);
 121         }
 122         db_count = sbi->s_gdb_count;
 123         for (i = 0; i < db_count; i++)
 124                 if (sbi->s_group_desc[i])
 125                         brelse (sbi->s_group_desc[i]);
 126         kfree(sbi->s_group_desc);
 127         kfree(sbi->s_debts);
 128         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 129         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 130         percpu_counter_destroy(&sbi->s_dirs_counter);
 131         brelse (sbi->s_sbh);
 132         sb->s_fs_info = NULL;
 133         kfree(sbi);
 134
 135         return;
 136 }
 137
 138 static kmem_cache_t * ext2_inode_cachep;
 139
 140 static struct inode *ext2_alloc_inode(struct super_block *sb)
 141 {
 142         struct ext2_inode_info *ei;
 143         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL);
 144         if (!ei)
 145                 return NULL;
 146 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 147         ei->i_acl = EXT2_ACL_NOT_CACHED;
 148         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 149 #endif
 150         ei->vfs_inode.i_version = 1;
 151         return &ei->vfs_inode;
 152 }
 153
 154 static void ext2_destroy_inode(struct inode *inode)
 155 {
 156         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
 157 }
 158
 159 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 160 {
 161         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
 162
 163         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 164             SLAB_CTOR_CONSTRUCTOR) {
 165                 rwlock_init(&ei->i_meta_lock);
 166 #ifdef CONFIG_EXT2_FS_XATTR
 167                 init_rwsem(&ei->xattr_sem);
 168 #endif
 169                 inode_init_once(&ei->vfs_inode);
 170         }
 171 }
 172
 173 static int init_inodecache(void)
 174 {
 175         ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
 176                                              sizeof(struct ext2_inode_info),
 177                                              0, (SLAB_RECLAIM_ACCOUNT|
 178                                                 SLAB_MEM_SPREAD),
 179                                              init_once, NULL);
 180         if (ext2_inode_cachep == NULL)
 181                 return -ENOMEM;
 182         return 0;
 183 }
 184
 185 static void destroy_inodecache(void)
 186 {
 187         kmem_cache_destroy(ext2_inode_cachep);
 188 }
 189
 190 static void ext2_clear_inode(struct inode *inode)
 191 {
 192 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 193         struct ext2_inode_info *ei = EXT2_I(inode);
 194
 195         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
 196                 posix_acl_release(ei->i_acl);
 197                 ei->i_acl = EXT2_ACL_NOT_CACHED;
 198         }
 199         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
 200                 posix_acl_release(ei->i_default_acl);
 201                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 202         }
 203 #endif
 204 }
 205
 206 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
 207 {
 208         struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
 209
 210         if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
 211                 seq_puts(seq, ",grpid");
 212
 213 #if defined(CONFIG_QUOTA)
 214         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
 215                 seq_puts(seq, ",usrquota");
 216
 217         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
 218                 seq_puts(seq, ",grpquota");
 219 #endif
 220
 221 #if defined(CONFIG_EXT2_FS_XIP)
 222         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
 223                 seq_puts(seq, ",xip");
 224 #endif
 225
 226         return 0;
 227 }
 228
 229 #ifdef CONFIG_QUOTA
 230 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
 231 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
 232 #endif
 233
 234 static struct super_operations ext2_sops = {
 235         .alloc_inode    = ext2_alloc_inode,
 236         .destroy_inode  = ext2_destroy_inode,
 237         .read_inode     = ext2_read_inode,
 238         .write_inode    = ext2_write_inode,
 239         .put_inode      = ext2_put_inode,
 240         .delete_inode   = ext2_delete_inode,
 241         .put_super      = ext2_put_super,
 242         .write_super    = ext2_write_super,
 243         .statfs         = ext2_statfs,
 244         .remount_fs     = ext2_remount,
 245         .clear_inode    = ext2_clear_inode,
 246         .show_options   = ext2_show_options,
 247 #ifdef CONFIG_QUOTA
 248         .quota_read     = ext2_quota_read,
 249         .quota_write    = ext2_quota_write,
 250 #endif
 251 };
 252
 253 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
 254 {
 255         __u32 *objp = vobjp;
 256         unsigned long ino = objp[0];
 257         __u32 generation = objp[1];
 258         struct inode *inode;
 259         struct dentry *result;
 260
 261         if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
 262                 return ERR_PTR(-ESTALE);
 263         if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
 264                 return ERR_PTR(-ESTALE);
 265
 266         /* iget isn't really right if the inode is currently unallocated!!
 267          * ext2_read_inode currently does appropriate checks, but
 268          * it might be "neater" to call ext2_get_inode first and check
 269          * if the inode is valid.....
 270          */
 271         inode = iget(sb, ino);
 272         if (inode == NULL)
 273                 return ERR_PTR(-ENOMEM);
 274         if (is_bad_inode(inode) ||
 275             (generation && inode->i_generation != generation)) {
 276                 /* we didn't find the right inode.. */
 277                 iput(inode);
 278                 return ERR_PTR(-ESTALE);
 279         }
 280         /* now to find a dentry.
 281          * If possible, get a well-connected one
 282          */
 283         result = d_alloc_anon(inode);
 284         if (!result) {
 285                 iput(inode);
 286                 return ERR_PTR(-ENOMEM);
 287         }
 288         return result;
 289 }
 290
 291 /* Yes, most of these are left as NULL!!
 292  * A NULL value implies the default, which works with ext2-like file
 293  * systems, but can be improved upon.
 294  * Currently only get_parent is required.
 295  */
 296 static struct export_operations ext2_export_ops = {
 297         .get_parent = ext2_get_parent,
 298         .get_dentry = ext2_get_dentry,
 299 };
 300
 301 static unsigned long get_sb_block(void **data)
 302 {
 303         unsigned long   sb_block;
 304         char            *options = (char *) *data;
 305
 306         if (!options || strncmp(options, "sb=", 3) != 0)
 307                 return 1;       /* Default location */
 308         options += 3;
 309         sb_block = simple_strtoul(options, &options, 0);
 310         if (*options && *options != ',') {
 311                 printk("EXT2-fs: Invalid sb specification: %s\n",
 312                        (char *) *data);
 313                 return 1;
 314         }
 315         if (*options == ',')
 316                 options++;
 317         *data = (void *) options;
 318         return sb_block;
 319 }
 320
 321 enum {
 322         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 323         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
 324         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
 325         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
 326         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
 327         Opt_usrquota, Opt_grpquota
 328 };
 329
 330 static match_table_t tokens = {
 331         {Opt_bsd_df, "bsddf"},
 332         {Opt_minix_df, "minixdf"},
 333         {Opt_grpid, "grpid"},
 334         {Opt_grpid, "bsdgroups"},
 335         {Opt_nogrpid, "nogrpid"},
 336         {Opt_nogrpid, "sysvgroups"},
 337         {Opt_resgid, "resgid=%u"},
 338         {Opt_resuid, "resuid=%u"},
 339         {Opt_sb, "sb=%u"},
 340         {Opt_err_cont, "errors=continue"},
 341         {Opt_err_panic, "errors=panic"},
 342         {Opt_err_ro, "errors=remount-ro"},
 343         {Opt_nouid32, "nouid32"},
 344         {Opt_nocheck, "check=none"},
 345         {Opt_nocheck, "nocheck"},
 346         {Opt_debug, "debug"},
 347         {Opt_oldalloc, "oldalloc"},
 348         {Opt_orlov, "orlov"},
 349         {Opt_nobh, "nobh"},
 350         {Opt_user_xattr, "user_xattr"},
 351         {Opt_nouser_xattr, "nouser_xattr"},
 352         {Opt_acl, "acl"},
 353         {Opt_noacl, "noacl"},
 354         {Opt_xip, "xip"},
 355         {Opt_grpquota, "grpquota"},
 356         {Opt_ignore, "noquota"},
 357         {Opt_quota, "quota"},
 358         {Opt_usrquota, "usrquota"},
 359         {Opt_err, NULL}
 360 };
 361
 362 static int parse_options (char * options,
 363                           struct ext2_sb_info *sbi)
 364 {
 365         char * p;
 366         substring_t args[MAX_OPT_ARGS];
 367         int option;
 368
 369         if (!options)
 370                 return 1;
 371
 372         while ((p = strsep (&options, ",")) != NULL) {
 373                 int token;
 374                 if (!*p)
 375                         continue;
 376
 377                 token = match_token(p, tokens, args);
 378                 switch (token) {
 379                 case Opt_bsd_df:
 380                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 381                         break;
 382                 case Opt_minix_df:
 383                         set_opt (sbi->s_mount_opt, MINIX_DF);
 384                         break;
 385                 case Opt_grpid:
 386                         set_opt (sbi->s_mount_opt, GRPID);
 387                         break;
 388                 case Opt_nogrpid:
 389                         clear_opt (sbi->s_mount_opt, GRPID);
 390                         break;
 391                 case Opt_resuid:
 392                         if (match_int(&args[0], &option))
 393                                 return 0;
 394                         sbi->s_resuid = option;
 395                         break;
 396                 case Opt_resgid:
 397                         if (match_int(&args[0], &option))
 398                                 return 0;
 399                         sbi->s_resgid = option;
 400                         break;
 401                 case Opt_sb:
 402                         /* handled by get_sb_block() instead of here */
 403                         /* *sb_block = match_int(&args[0]); */
 404                         break;
 405                 case Opt_err_panic:
 406                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
 407                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
 408                         set_opt (sbi->s_mount_opt, ERRORS_PANIC);
 409                         break;
 410                 case Opt_err_ro:
 411                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
 412                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
 413                         set_opt (sbi->s_mount_opt, ERRORS_RO);
 414                         break;
 415                 case Opt_err_cont:
 416                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
 417                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
 418                         set_opt (sbi->s_mount_opt, ERRORS_CONT);
 419                         break;
 420                 case Opt_nouid32:
 421                         set_opt (sbi->s_mount_opt, NO_UID32);
 422                         break;
 423                 case Opt_nocheck:
 424                         clear_opt (sbi->s_mount_opt, CHECK);
 425                         break;
 426                 case Opt_debug:
 427                         set_opt (sbi->s_mount_opt, DEBUG);
 428                         break;
 429                 case Opt_oldalloc:
 430                         set_opt (sbi->s_mount_opt, OLDALLOC);
 431                         break;
 432                 case Opt_orlov:
 433                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 434                         break;
 435                 case Opt_nobh:
 436                         set_opt (sbi->s_mount_opt, NOBH);
 437                         break;
 438 #ifdef CONFIG_EXT2_FS_XATTR
 439                 case Opt_user_xattr:
 440                         set_opt (sbi->s_mount_opt, XATTR_USER);
 441                         break;
 442                 case Opt_nouser_xattr:
 443                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 444                         break;
 445 #else
 446                 case Opt_user_xattr:
 447                 case Opt_nouser_xattr:
 448                         printk("EXT2 (no)user_xattr options not supported\n");
 449                         break;
 450 #endif
 451 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 452                 case Opt_acl:
 453                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 454                         break;
 455                 case Opt_noacl:
 456                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 457                         break;
 458 #else
 459                 case Opt_acl:
 460                 case Opt_noacl:
 461                         printk("EXT2 (no)acl options not supported\n");
 462                         break;
 463 #endif
 464                 case Opt_xip:
 465 #ifdef CONFIG_EXT2_FS_XIP
 466                         set_opt (sbi->s_mount_opt, XIP);
 467 #else
 468                         printk("EXT2 xip option not supported\n");
 469 #endif
 470                         break;
 471
 472 #if defined(CONFIG_QUOTA)
 473                 case Opt_quota:
 474                 case Opt_usrquota:
 475                         set_opt(sbi->s_mount_opt, USRQUOTA);
 476                         break;
 477
 478                 case Opt_grpquota:
 479                         set_opt(sbi->s_mount_opt, GRPQUOTA);
 480                         break;
 481 #else
 482                 case Opt_quota:
 483                 case Opt_usrquota:
 484                 case Opt_grpquota:
 485                         printk(KERN_ERR
 486                                 "EXT2-fs: quota operations not supported.\n");
 487
 488                         break;
 489 #endif
 490
 491                 case Opt_ignore:
 492                         break;
 493                 default:
 494                         return 0;
 495                 }
 496         }
 497         return 1;
 498 }
 499
 500 static int ext2_setup_super (struct super_block * sb,
 501                               struct ext2_super_block * es,
 502                               int read_only)
 503 {
 504         int res = 0;
 505         struct ext2_sb_info *sbi = EXT2_SB(sb);
 506
 507         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 508                 printk ("EXT2-fs warning: revision level too high, "
 509                         "forcing read-only mode\n");
 510                 res = MS_RDONLY;
 511         }
 512         if (read_only)
 513                 return res;
 514         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 515                 printk ("EXT2-fs warning: mounting unchecked fs, "
 516                         "running e2fsck is recommended\n");
 517         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 518                 printk ("EXT2-fs warning: mounting fs with errors, "
 519                         "running e2fsck is recommended\n");
 520         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 521                  le16_to_cpu(es->s_mnt_count) >=
 522                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 523                 printk ("EXT2-fs warning: maximal mount count reached, "
 524                         "running e2fsck is recommended\n");
 525         else if (le32_to_cpu(es->s_checkinterval) &&
 526                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 527                 printk ("EXT2-fs warning: checktime reached, "
 528                         "running e2fsck is recommended\n");
 529         if (!le16_to_cpu(es->s_max_mnt_count))
 530                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 531         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 532         ext2_write_super(sb);
 533         if (test_opt (sb, DEBUG))
 534                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 535                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 536                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 537                         sbi->s_frag_size,
 538                         sbi->s_groups_count,
 539                         EXT2_BLOCKS_PER_GROUP(sb),
 540                         EXT2_INODES_PER_GROUP(sb),
 541                         sbi->s_mount_opt);
 542         return res;
 543 }
 544
 545 static int ext2_check_descriptors (struct super_block * sb)
 546 {
 547         int i;
 548         int desc_block = 0;
 549         struct ext2_sb_info *sbi = EXT2_SB(sb);
 550         unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 551         unsigned long last_block;
 552         struct ext2_group_desc * gdp = NULL;
 553
 554         ext2_debug ("Checking group descriptors");
 555
 556         for (i = 0; i < sbi->s_groups_count; i++)
 557         {
 558                 if (i == sbi->s_groups_count - 1)
 559                         last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
 560                 else
 561                         last_block = first_block +
 562                                 (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 563
 564                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 565                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 566                 if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
 567                     le32_to_cpu(gdp->bg_block_bitmap) > last_block)
 568                 {
 569                         ext2_error (sb, "ext2_check_descriptors",
 570                                     "Block bitmap for group %d"
 571                                     " not in group (block %lu)!",
 572                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 573                         return 0;
 574                 }
 575                 if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
 576                     le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
 577                 {
 578                         ext2_error (sb, "ext2_check_descriptors",
 579                                     "Inode bitmap for group %d"
 580                                     " not in group (block %lu)!",
 581                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 582                         return 0;
 583                 }
 584                 if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
 585                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
 586                     last_block)
 587                 {
 588                         ext2_error (sb, "ext2_check_descriptors",
 589                                     "Inode table for group %d"
 590                                     " not in group (block %lu)!",
 591                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 592                         return 0;
 593                 }
 594                 first_block += EXT2_BLOCKS_PER_GROUP(sb);
 595                 gdp++;
 596         }
 597         return 1;
 598 }
 599
 600 #define log2(n) ffz(~(n))
 601
 602 /*
 603  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 604  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 605  * We need to be 1 filesystem block less than the 2^32 sector limit.
 606  */
 607 static loff_t ext2_max_size(int bits)
 608 {
 609         loff_t res = EXT2_NDIR_BLOCKS;
 610         /* This constant is calculated to be the largest file size for a
 611          * dense, 4k-blocksize file such that the total number of
 612          * sectors in the file, including data and all indirect blocks,
 613          * does not exceed 2^32. */
 614         const loff_t upper_limit = 0x1ff7fffd000LL;
 615
 616         res += 1LL << (bits-2);
 617         res += 1LL << (2*(bits-2));
 618         res += 1LL << (3*(bits-2));
 619         res <<= bits;
 620         if (res > upper_limit)
 621                 res = upper_limit;
 622         return res;
 623 }
 624
 625 static unsigned long descriptor_loc(struct super_block *sb,
 626                                     unsigned long logic_sb_block,
 627                                     int nr)
 628 {
 629         struct ext2_sb_info *sbi = EXT2_SB(sb);
 630         unsigned long bg, first_data_block, first_meta_bg;
 631         int has_super = 0;
 632
 633         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 634         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 635
 636         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 637             nr < first_meta_bg)
 638                 return (logic_sb_block + nr + 1);
 639         bg = sbi->s_desc_per_block * nr;
 640         if (ext2_bg_has_super(sb, bg))
 641                 has_super = 1;
 642         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 643 }
 644
 645 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 646 {
 647         struct buffer_head * bh;
 648         struct ext2_sb_info * sbi;
 649         struct ext2_super_block * es;
 650         struct inode *root;
 651         unsigned long block;
 652         unsigned long sb_block = get_sb_block(&data);
 653         unsigned long logic_sb_block;
 654         unsigned long offset = 0;
 655         unsigned long def_mount_opts;
 656         int blocksize = BLOCK_SIZE;
 657         int db_count;
 658         int i, j;
 659         __le32 features;
 660
 661         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 662         if (!sbi)
 663                 return -ENOMEM;
 664         sb->s_fs_info = sbi;
 665
 666         /*
 667          * See what the current blocksize for the device is, and
 668          * use that as the blocksize.  Otherwise (or if the blocksize
 669          * is smaller than the default) use the default.
 670          * This is important for devices that have a hardware
 671          * sectorsize that is larger than the default.
 672          */
 673         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 674         if (!blocksize) {
 675                 printk ("EXT2-fs: unable to set blocksize\n");
 676                 goto failed_sbi;
 677         }
 678
 679         /*
 680          * If the superblock doesn't start on a hardware sector boundary,
 681          * calculate the offset.
 682          */
 683         if (blocksize != BLOCK_SIZE) {
 684                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 685                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 686         } else {
 687                 logic_sb_block = sb_block;
 688         }
 689
 690         if (!(bh = sb_bread(sb, logic_sb_block))) {
 691                 printk ("EXT2-fs: unable to read superblock\n");
 692                 goto failed_sbi;
 693         }
 694         /*
 695          * Note: s_es must be initialized as soon as possible because
 696          *       some ext2 macro-instructions depend on its value
 697          */
 698         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 699         sbi->s_es = es;
 700         sb->s_magic = le16_to_cpu(es->s_magic);
 701
 702         if (sb->s_magic != EXT2_SUPER_MAGIC)
 703                 goto cantfind_ext2;
 704
 705         /* Set defaults before we parse the mount options */
 706         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 707         if (def_mount_opts & EXT2_DEFM_DEBUG)
 708                 set_opt(sbi->s_mount_opt, DEBUG);
 709         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 710                 set_opt(sbi->s_mount_opt, GRPID);
 711         if (def_mount_opts & EXT2_DEFM_UID16)
 712                 set_opt(sbi->s_mount_opt, NO_UID32);
 713         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 714                 set_opt(sbi->s_mount_opt, XATTR_USER);
 715         if (def_mount_opts & EXT2_DEFM_ACL)
 716                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 717
 718         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 719                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 720         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 721                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 722         else
 723                 set_opt(sbi->s_mount_opt, ERRORS_CONT);
 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         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 732                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 733                  MS_POSIXACL : 0);
 734
 735         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
 736                                     EXT2_MOUNT_XIP if not */
 737
 738         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 739             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 740              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 741              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 742                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 743                        "running e2fsck is recommended\n");
 744         /*
 745          * Check feature flags regardless of the revision level, since we
 746          * previously didn't change the revision level when setting the flags,
 747          * so there is a chance incompat flags are set on a rev 0 filesystem.
 748          */
 749         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 750         if (features) {
 751                 printk("EXT2-fs: %s: couldn't mount because of "
 752                        "unsupported optional features (%x).\n",
 753                        sb->s_id, le32_to_cpu(features));
 754                 goto failed_mount;
 755         }
 756         if (!(sb->s_flags & MS_RDONLY) &&
 757             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 758                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 759                        "unsupported optional features (%x).\n",
 760                        sb->s_id, le32_to_cpu(features));
 761                 goto failed_mount;
 762         }
 763
 764         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 765
 766         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
 767                                   (sb->s_blocksize != blocksize))) {
 768                 if (!silent)
 769                         printk("XIP: Unsupported blocksize\n");
 770                 goto failed_mount;
 771         }
 772
 773         /* If the blocksize doesn't match, re-read the thing.. */
 774         if (sb->s_blocksize != blocksize) {
 775                 brelse(bh);
 776
 777                 if (!sb_set_blocksize(sb, blocksize)) {
 778                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 779                         goto failed_sbi;
 780                 }
 781
 782                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 783                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 784                 bh = sb_bread(sb, logic_sb_block);
 785                 if(!bh) {
 786                         printk("EXT2-fs: Couldn't read superblock on "
 787                                "2nd try.\n");
 788                         goto failed_sbi;
 789                 }
 790                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 791                 sbi->s_es = es;
 792                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 793                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 794                         goto failed_mount;
 795                 }
 796         }
 797
 798         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 799
 800         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 801                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 802                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 803         } else {
 804                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 805                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 806                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 807                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 808                     (sbi->s_inode_size > blocksize)) {
 809                         printk ("EXT2-fs: unsupported inode size: %d\n",
 810                                 sbi->s_inode_size);
 811                         goto failed_mount;
 812                 }
 813         }
 814
 815         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 816                                    le32_to_cpu(es->s_log_frag_size);
 817         if (sbi->s_frag_size == 0)
 818                 goto cantfind_ext2;
 819         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 820
 821         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 822         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 823         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 824
 825         if (EXT2_INODE_SIZE(sb) == 0)
 826                 goto cantfind_ext2;
 827         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 828         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
 829                 goto cantfind_ext2;
 830         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 831                                         sbi->s_inodes_per_block;
 832         sbi->s_desc_per_block = sb->s_blocksize /
 833                                         sizeof (struct ext2_group_desc);
 834         sbi->s_sbh = bh;
 835         sbi->s_mount_state = le16_to_cpu(es->s_state);
 836         sbi->s_addr_per_block_bits =
 837                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 838         sbi->s_desc_per_block_bits =
 839                 log2 (EXT2_DESC_PER_BLOCK(sb));
 840
 841         if (sb->s_magic != EXT2_SUPER_MAGIC)
 842                 goto cantfind_ext2;
 843
 844         if (sb->s_blocksize != bh->b_size) {
 845                 if (!silent)
 846                         printk ("VFS: Unsupported blocksize on dev "
 847                                 "%s.\n", sb->s_id);
 848                 goto failed_mount;
 849         }
 850
 851         if (sb->s_blocksize != sbi->s_frag_size) {
 852                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 853                         sbi->s_frag_size, sb->s_blocksize);
 854                 goto failed_mount;
 855         }
 856
 857         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 858                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 859                         sbi->s_blocks_per_group);
 860                 goto failed_mount;
 861         }
 862         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 863                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 864                         sbi->s_frags_per_group);
 865                 goto failed_mount;
 866         }
 867         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 868                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 869                         sbi->s_inodes_per_group);
 870                 goto failed_mount;
 871         }
 872
 873         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 874                 goto cantfind_ext2;
 875         sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
 876                                 le32_to_cpu(es->s_first_data_block) - 1)
 877                                         / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
 878         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 879                    EXT2_DESC_PER_BLOCK(sb);
 880         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 881         if (sbi->s_group_desc == NULL) {
 882                 printk ("EXT2-fs: not enough memory\n");
 883                 goto failed_mount;
 884         }
 885         bgl_lock_init(&sbi->s_blockgroup_lock);
 886         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 887                                GFP_KERNEL);
 888         if (!sbi->s_debts) {
 889                 printk ("EXT2-fs: not enough memory\n");
 890                 goto failed_mount_group_desc;
 891         }
 892         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 893         for (i = 0; i < db_count; i++) {
 894                 block = descriptor_loc(sb, logic_sb_block, i);
 895                 sbi->s_group_desc[i] = sb_bread(sb, block);
 896                 if (!sbi->s_group_desc[i]) {
 897                         for (j = 0; j < i; j++)
 898                                 brelse (sbi->s_group_desc[j]);
 899                         printk ("EXT2-fs: unable to read group descriptors\n");
 900                         goto failed_mount_group_desc;
 901                 }
 902         }
 903         if (!ext2_check_descriptors (sb)) {
 904                 printk ("EXT2-fs: group descriptors corrupted!\n");
 905                 goto failed_mount2;
 906         }
 907         sbi->s_gdb_count = db_count;
 908         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 909         spin_lock_init(&sbi->s_next_gen_lock);
 910
 911         percpu_counter_init(&sbi->s_freeblocks_counter,
 912                                 ext2_count_free_blocks(sb));
 913         percpu_counter_init(&sbi->s_freeinodes_counter,
 914                                 ext2_count_free_inodes(sb));
 915         percpu_counter_init(&sbi->s_dirs_counter,
 916                                 ext2_count_dirs(sb));
 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_mount3;
 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_mount3;
 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         return 0;
 941
 942 cantfind_ext2:
 943         if (!silent)
 944                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 945                        sb->s_id);
 946         goto failed_mount;
 947 failed_mount3:
 948         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 949         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 950         percpu_counter_destroy(&sbi->s_dirs_counter);
 951 failed_mount2:
 952         for (i = 0; i < db_count; i++)
 953                 brelse(sbi->s_group_desc[i]);
 954 failed_mount_group_desc:
 955         kfree(sbi->s_group_desc);
 956         kfree(sbi->s_debts);
 957 failed_mount:
 958         brelse(bh);
 959 failed_sbi:
 960         sb->s_fs_info = NULL;
 961         kfree(sbi);
 962         return -EINVAL;
 963 }
 964
 965 static void ext2_commit_super (struct super_block * sb,
 966                                struct ext2_super_block * es)
 967 {
 968         es->s_wtime = cpu_to_le32(get_seconds());
 969         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 970         sb->s_dirt = 0;
 971 }
 972
 973 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 974 {
 975         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 976         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 977         es->s_wtime = cpu_to_le32(get_seconds());
 978         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 979         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 980         sb->s_dirt = 0;
 981 }
 982
 983 /*
 984  * In the second extended file system, it is not necessary to
 985  * write the super block since we use a mapping of the
 986  * disk super block in a buffer.
 987  *
 988  * However, this function is still used to set the fs valid
 989  * flags to 0.  We need to set this flag to 0 since the fs
 990  * may have been checked while mounted and e2fsck may have
 991  * set s_state to EXT2_VALID_FS after some corrections.
 992  */
 993
 994 void ext2_write_super (struct super_block * sb)
 995 {
 996         struct ext2_super_block * es;
 997         lock_kernel();
 998         if (!(sb->s_flags & MS_RDONLY)) {
 999                 es = EXT2_SB(sb)->s_es;
1000
1001                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1002                         ext2_debug ("setting valid to 0\n");
1003                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1004                                                   ~EXT2_VALID_FS);
1005                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1006                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1007                         es->s_mtime = cpu_to_le32(get_seconds());
1008                         ext2_sync_super(sb, es);
1009                 } else
1010                         ext2_commit_super (sb, es);
1011         }
1012         sb->s_dirt = 0;
1013         unlock_kernel();
1014 }
1015
1016 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1017 {
1018         struct ext2_sb_info * sbi = EXT2_SB(sb);
1019         struct ext2_super_block * es;
1020         unsigned long old_mount_opt = sbi->s_mount_opt;
1021         struct ext2_mount_options old_opts;
1022         unsigned long old_sb_flags;
1023         int err;
1024
1025         /* Store the old options */
1026         old_sb_flags = sb->s_flags;
1027         old_opts.s_mount_opt = sbi->s_mount_opt;
1028         old_opts.s_resuid = sbi->s_resuid;
1029         old_opts.s_resgid = sbi->s_resgid;
1030
1031         /*
1032          * Allow the "check" option to be passed as a remount option.
1033          */
1034         if (!parse_options (data, sbi)) {
1035                 err = -EINVAL;
1036                 goto restore_opts;
1037         }
1038
1039         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1040                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1041
1042         es = sbi->s_es;
1043         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1044             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1045             invalidate_inodes(sb))
1046                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1047                              "xip remain in cache (no functional problem)");
1048         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1049                 return 0;
1050         if (*flags & MS_RDONLY) {
1051                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1052                     !(sbi->s_mount_state & EXT2_VALID_FS))
1053                         return 0;
1054                 /*
1055                  * OK, we are remounting a valid rw partition rdonly, so set
1056                  * the rdonly flag and then mark the partition as valid again.
1057                  */
1058                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1059                 es->s_mtime = cpu_to_le32(get_seconds());
1060         } else {
1061                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1062                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1063                 if (ret) {
1064                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1065                                "unsupported optional features (%x).\n",
1066                                sb->s_id, le32_to_cpu(ret));
1067                         err = -EROFS;
1068                         goto restore_opts;
1069                 }
1070                 /*
1071                  * Mounting a RDONLY partition read-write, so reread and
1072                  * store the current valid flag.  (It may have been changed
1073                  * by e2fsck since we originally mounted the partition.)
1074                  */
1075                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1076                 if (!ext2_setup_super (sb, es, 0))
1077                         sb->s_flags &= ~MS_RDONLY;
1078         }
1079         ext2_sync_super(sb, es);
1080         return 0;
1081 restore_opts:
1082         sbi->s_mount_opt = old_opts.s_mount_opt;
1083         sbi->s_resuid = old_opts.s_resuid;
1084         sbi->s_resgid = old_opts.s_resgid;
1085         sb->s_flags = old_sb_flags;
1086         return err;
1087 }
1088
1089 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1090 {
1091         struct super_block *sb = dentry->d_sb;
1092         struct ext2_sb_info *sbi = EXT2_SB(sb);
1093         unsigned long overhead;
1094         int i;
1095
1096         if (test_opt (sb, MINIX_DF))
1097                 overhead = 0;
1098         else {
1099                 /*
1100                  * Compute the overhead (FS structures)
1101                  */
1102
1103                 /*
1104                  * All of the blocks before first_data_block are
1105                  * overhead
1106                  */
1107                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1108
1109                 /*
1110                  * Add the overhead attributed to the superblock and
1111                  * block group descriptors.  If the sparse superblocks
1112                  * feature is turned on, then not all groups have this.
1113                  */
1114                 for (i = 0; i < sbi->s_groups_count; i++)
1115                         overhead += ext2_bg_has_super(sb, i) +
1116                                 ext2_bg_num_gdb(sb, i);
1117
1118                 /*
1119                  * Every block group has an inode bitmap, a block
1120                  * bitmap, and an inode table.
1121                  */
1122                 overhead += (sbi->s_groups_count *
1123                              (2 + sbi->s_itb_per_group));
1124         }
1125
1126         buf->f_type = EXT2_SUPER_MAGIC;
1127         buf->f_bsize = sb->s_blocksize;
1128         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1129         buf->f_bfree = ext2_count_free_blocks(sb);
1130         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1131         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1132                 buf->f_bavail = 0;
1133         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1134         buf->f_ffree = ext2_count_free_inodes (sb);
1135         buf->f_namelen = EXT2_NAME_LEN;
1136         return 0;
1137 }
1138
1139 static int ext2_get_sb(struct file_system_type *fs_type,
1140         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1141 {
1142         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1143 }
1144
1145 #ifdef CONFIG_QUOTA
1146
1147 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1148  * acquiring the locks... As quota files are never truncated and quota code
1149  * itself serializes the operations (and noone else should touch the files)
1150  * we don't have to be afraid of races */
1151 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1152                                size_t len, loff_t off)
1153 {
1154         struct inode *inode = sb_dqopt(sb)->files[type];
1155         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1156         int err = 0;
1157         int offset = off & (sb->s_blocksize - 1);
1158         int tocopy;
1159         size_t toread;
1160         struct buffer_head tmp_bh;
1161         struct buffer_head *bh;
1162         loff_t i_size = i_size_read(inode);
1163
1164         if (off > i_size)
1165                 return 0;
1166         if (off+len > i_size)
1167                 len = i_size-off;
1168         toread = len;
1169         while (toread > 0) {
1170                 tocopy = sb->s_blocksize - offset < toread ?
1171                                 sb->s_blocksize - offset : toread;
1172
1173                 tmp_bh.b_state = 0;
1174                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1175                 if (err)
1176                         return err;
1177                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1178                         memset(data, 0, tocopy);
1179                 else {
1180                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1181                         if (!bh)
1182                                 return -EIO;
1183                         memcpy(data, bh->b_data+offset, tocopy);
1184                         brelse(bh);
1185                 }
1186                 offset = 0;
1187                 toread -= tocopy;
1188                 data += tocopy;
1189                 blk++;
1190         }
1191         return len;
1192 }
1193
1194 /* Write to quotafile */
1195 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1196                                 const char *data, size_t len, loff_t off)
1197 {
1198         struct inode *inode = sb_dqopt(sb)->files[type];
1199         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1200         int err = 0;
1201         int offset = off & (sb->s_blocksize - 1);
1202         int tocopy;
1203         size_t towrite = len;
1204         struct buffer_head tmp_bh;
1205         struct buffer_head *bh;
1206
1207         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1208         while (towrite > 0) {
1209                 tocopy = sb->s_blocksize - offset < towrite ?
1210                                 sb->s_blocksize - offset : towrite;
1211
1212                 tmp_bh.b_state = 0;
1213                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1214                 if (err)
1215                         goto out;
1216                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1217                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1218                 else
1219                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1220                 if (!bh) {
1221                         err = -EIO;
1222                         goto out;
1223                 }
1224                 lock_buffer(bh);
1225                 memcpy(bh->b_data+offset, data, tocopy);
1226                 flush_dcache_page(bh->b_page);
1227                 set_buffer_uptodate(bh);
1228                 mark_buffer_dirty(bh);
1229                 unlock_buffer(bh);
1230                 brelse(bh);
1231                 offset = 0;
1232                 towrite -= tocopy;
1233                 data += tocopy;
1234                 blk++;
1235         }
1236 out:
1237         if (len == towrite)
1238                 return err;
1239         if (inode->i_size < off+len-towrite)
1240                 i_size_write(inode, off+len-towrite);
1241         inode->i_version++;
1242         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1243         mark_inode_dirty(inode);
1244         mutex_unlock(&inode->i_mutex);
1245         return len - towrite;
1246 }
1247
1248 #endif
1249
1250 static struct file_system_type ext2_fs_type = {
1251         .owner          = THIS_MODULE,
1252         .name           = "ext2",
1253         .get_sb         = ext2_get_sb,
1254         .kill_sb        = kill_block_super,
1255         .fs_flags       = FS_REQUIRES_DEV,
1256 };
1257
1258 static int __init init_ext2_fs(void)
1259 {
1260         int err = init_ext2_xattr();
1261         if (err)
1262                 return err;
1263         err = init_inodecache();
1264         if (err)
1265                 goto out1;
1266         err = register_filesystem(&ext2_fs_type);
1267         if (err)
1268                 goto out;
1269         return 0;
1270 out:
1271         destroy_inodecache();
1272 out1:
1273         exit_ext2_xattr();
1274         return err;
1275 }
1276
1277 static void __exit exit_ext2_fs(void)
1278 {
1279         unregister_filesystem(&ext2_fs_type);
1280         destroy_inodecache();
1281         exit_ext2_xattr();
1282 }
1283
1284 module_init(init_ext2_fs)
1285 module_exit(exit_ext2_fs)