[PATCH] VFS: Permit filesystem to override root dentry on mount
[linux-2.6.git] / 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                                                 SLAB_MEM_SPREAD),
180                                              init_once, NULL);
181         if (ext2_inode_cachep == NULL)
182                 return -ENOMEM;
183         return 0;
184 }
185
186 static void destroy_inodecache(void)
187 {
188         if (kmem_cache_destroy(ext2_inode_cachep))
189                 printk(KERN_INFO "ext2_inode_cache: not all structures were freed\n");
190 }
191
192 static void ext2_clear_inode(struct inode *inode)
193 {
194 #ifdef CONFIG_EXT2_FS_POSIX_ACL
195         struct ext2_inode_info *ei = EXT2_I(inode);
196
197         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
198                 posix_acl_release(ei->i_acl);
199                 ei->i_acl = EXT2_ACL_NOT_CACHED;
200         }
201         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
202                 posix_acl_release(ei->i_default_acl);
203                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
204         }
205 #endif
206 }
207
208 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
209 {
210         struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
211
212         if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
213                 seq_puts(seq, ",grpid");
214
215 #if defined(CONFIG_QUOTA)
216         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
217                 seq_puts(seq, ",usrquota");
218
219         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
220                 seq_puts(seq, ",grpquota");
221 #endif
222
223 #if defined(CONFIG_EXT2_FS_XIP)
224         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
225                 seq_puts(seq, ",xip");
226 #endif
227
228         return 0;
229 }
230
231 #ifdef CONFIG_QUOTA
232 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
233 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
234 #endif
235
236 static struct super_operations ext2_sops = {
237         .alloc_inode    = ext2_alloc_inode,
238         .destroy_inode  = ext2_destroy_inode,
239         .read_inode     = ext2_read_inode,
240         .write_inode    = ext2_write_inode,
241         .put_inode      = ext2_put_inode,
242         .delete_inode   = ext2_delete_inode,
243         .put_super      = ext2_put_super,
244         .write_super    = ext2_write_super,
245         .statfs         = ext2_statfs,
246         .remount_fs     = ext2_remount,
247         .clear_inode    = ext2_clear_inode,
248         .show_options   = ext2_show_options,
249 #ifdef CONFIG_QUOTA
250         .quota_read     = ext2_quota_read,
251         .quota_write    = ext2_quota_write,
252 #endif
253 };
254
255 /* Yes, most of these are left as NULL!!
256  * A NULL value implies the default, which works with ext2-like file
257  * systems, but can be improved upon.
258  * Currently only get_parent is required.
259  */
260 static struct export_operations ext2_export_ops = {
261         .get_parent = ext2_get_parent,
262 };
263
264 static unsigned long get_sb_block(void **data)
265 {
266         unsigned long   sb_block;
267         char            *options = (char *) *data;
268
269         if (!options || strncmp(options, "sb=", 3) != 0)
270                 return 1;       /* Default location */
271         options += 3;
272         sb_block = simple_strtoul(options, &options, 0);
273         if (*options && *options != ',') {
274                 printk("EXT2-fs: Invalid sb specification: %s\n",
275                        (char *) *data);
276                 return 1;
277         }
278         if (*options == ',')
279                 options++;
280         *data = (void *) options;
281         return sb_block;
282 }
283
284 enum {
285         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
286         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
287         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
288         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
289         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
290         Opt_usrquota, Opt_grpquota
291 };
292
293 static match_table_t tokens = {
294         {Opt_bsd_df, "bsddf"},
295         {Opt_minix_df, "minixdf"},
296         {Opt_grpid, "grpid"},
297         {Opt_grpid, "bsdgroups"},
298         {Opt_nogrpid, "nogrpid"},
299         {Opt_nogrpid, "sysvgroups"},
300         {Opt_resgid, "resgid=%u"},
301         {Opt_resuid, "resuid=%u"},
302         {Opt_sb, "sb=%u"},
303         {Opt_err_cont, "errors=continue"},
304         {Opt_err_panic, "errors=panic"},
305         {Opt_err_ro, "errors=remount-ro"},
306         {Opt_nouid32, "nouid32"},
307         {Opt_nocheck, "check=none"},
308         {Opt_nocheck, "nocheck"},
309         {Opt_debug, "debug"},
310         {Opt_oldalloc, "oldalloc"},
311         {Opt_orlov, "orlov"},
312         {Opt_nobh, "nobh"},
313         {Opt_user_xattr, "user_xattr"},
314         {Opt_nouser_xattr, "nouser_xattr"},
315         {Opt_acl, "acl"},
316         {Opt_noacl, "noacl"},
317         {Opt_xip, "xip"},
318         {Opt_grpquota, "grpquota"},
319         {Opt_ignore, "noquota"},
320         {Opt_quota, "quota"},
321         {Opt_usrquota, "usrquota"},
322         {Opt_err, NULL}
323 };
324
325 static int parse_options (char * options,
326                           struct ext2_sb_info *sbi)
327 {
328         char * p;
329         substring_t args[MAX_OPT_ARGS];
330         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
331         int option;
332
333         if (!options)
334                 return 1;
335
336         while ((p = strsep (&options, ",")) != NULL) {
337                 int token;
338                 if (!*p)
339                         continue;
340
341                 token = match_token(p, tokens, args);
342                 switch (token) {
343                 case Opt_bsd_df:
344                         clear_opt (sbi->s_mount_opt, MINIX_DF);
345                         break;
346                 case Opt_minix_df:
347                         set_opt (sbi->s_mount_opt, MINIX_DF);
348                         break;
349                 case Opt_grpid:
350                         set_opt (sbi->s_mount_opt, GRPID);
351                         break;
352                 case Opt_nogrpid:
353                         clear_opt (sbi->s_mount_opt, GRPID);
354                         break;
355                 case Opt_resuid:
356                         if (match_int(&args[0], &option))
357                                 return 0;
358                         sbi->s_resuid = option;
359                         break;
360                 case Opt_resgid:
361                         if (match_int(&args[0], &option))
362                                 return 0;
363                         sbi->s_resgid = option;
364                         break;
365                 case Opt_sb:
366                         /* handled by get_sb_block() instead of here */
367                         /* *sb_block = match_int(&args[0]); */
368                         break;
369                 case Opt_err_panic:
370                         kind = EXT2_MOUNT_ERRORS_PANIC;
371                         break;
372                 case Opt_err_ro:
373                         kind = EXT2_MOUNT_ERRORS_RO;
374                         break;
375                 case Opt_err_cont:
376                         kind = EXT2_MOUNT_ERRORS_CONT;
377                         break;
378                 case Opt_nouid32:
379                         set_opt (sbi->s_mount_opt, NO_UID32);
380                         break;
381                 case Opt_nocheck:
382                         clear_opt (sbi->s_mount_opt, CHECK);
383                         break;
384                 case Opt_debug:
385                         set_opt (sbi->s_mount_opt, DEBUG);
386                         break;
387                 case Opt_oldalloc:
388                         set_opt (sbi->s_mount_opt, OLDALLOC);
389                         break;
390                 case Opt_orlov:
391                         clear_opt (sbi->s_mount_opt, OLDALLOC);
392                         break;
393                 case Opt_nobh:
394                         set_opt (sbi->s_mount_opt, NOBH);
395                         break;
396 #ifdef CONFIG_EXT2_FS_XATTR
397                 case Opt_user_xattr:
398                         set_opt (sbi->s_mount_opt, XATTR_USER);
399                         break;
400                 case Opt_nouser_xattr:
401                         clear_opt (sbi->s_mount_opt, XATTR_USER);
402                         break;
403 #else
404                 case Opt_user_xattr:
405                 case Opt_nouser_xattr:
406                         printk("EXT2 (no)user_xattr options not supported\n");
407                         break;
408 #endif
409 #ifdef CONFIG_EXT2_FS_POSIX_ACL
410                 case Opt_acl:
411                         set_opt(sbi->s_mount_opt, POSIX_ACL);
412                         break;
413                 case Opt_noacl:
414                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
415                         break;
416 #else
417                 case Opt_acl:
418                 case Opt_noacl:
419                         printk("EXT2 (no)acl options not supported\n");
420                         break;
421 #endif
422                 case Opt_xip:
423 #ifdef CONFIG_EXT2_FS_XIP
424                         set_opt (sbi->s_mount_opt, XIP);
425 #else
426                         printk("EXT2 xip option not supported\n");
427 #endif
428                         break;
429
430 #if defined(CONFIG_QUOTA)
431                 case Opt_quota:
432                 case Opt_usrquota:
433                         set_opt(sbi->s_mount_opt, USRQUOTA);
434                         break;
435
436                 case Opt_grpquota:
437                         set_opt(sbi->s_mount_opt, GRPQUOTA);
438                         break;
439 #else
440                 case Opt_quota:
441                 case Opt_usrquota:
442                 case Opt_grpquota:
443                         printk(KERN_ERR
444                                 "EXT2-fs: quota operations not supported.\n");
445
446                         break;
447 #endif
448
449                 case Opt_ignore:
450                         break;
451                 default:
452                         return 0;
453                 }
454         }
455         sbi->s_mount_opt |= kind;
456         return 1;
457 }
458
459 static int ext2_setup_super (struct super_block * sb,
460                               struct ext2_super_block * es,
461                               int read_only)
462 {
463         int res = 0;
464         struct ext2_sb_info *sbi = EXT2_SB(sb);
465
466         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
467                 printk ("EXT2-fs warning: revision level too high, "
468                         "forcing read-only mode\n");
469                 res = MS_RDONLY;
470         }
471         if (read_only)
472                 return res;
473         if (!(sbi->s_mount_state & EXT2_VALID_FS))
474                 printk ("EXT2-fs warning: mounting unchecked fs, "
475                         "running e2fsck is recommended\n");
476         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
477                 printk ("EXT2-fs warning: mounting fs with errors, "
478                         "running e2fsck is recommended\n");
479         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
480                  le16_to_cpu(es->s_mnt_count) >=
481                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
482                 printk ("EXT2-fs warning: maximal mount count reached, "
483                         "running e2fsck is recommended\n");
484         else if (le32_to_cpu(es->s_checkinterval) &&
485                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
486                 printk ("EXT2-fs warning: checktime reached, "
487                         "running e2fsck is recommended\n");
488         if (!le16_to_cpu(es->s_max_mnt_count))
489                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
490         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
491         ext2_write_super(sb);
492         if (test_opt (sb, DEBUG))
493                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
494                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
495                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
496                         sbi->s_frag_size,
497                         sbi->s_groups_count,
498                         EXT2_BLOCKS_PER_GROUP(sb),
499                         EXT2_INODES_PER_GROUP(sb),
500                         sbi->s_mount_opt);
501         return res;
502 }
503
504 static int ext2_check_descriptors (struct super_block * sb)
505 {
506         int i;
507         int desc_block = 0;
508         struct ext2_sb_info *sbi = EXT2_SB(sb);
509         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
510         struct ext2_group_desc * gdp = NULL;
511
512         ext2_debug ("Checking group descriptors");
513
514         for (i = 0; i < sbi->s_groups_count; i++)
515         {
516                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
517                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
518                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
519                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
520                 {
521                         ext2_error (sb, "ext2_check_descriptors",
522                                     "Block bitmap for group %d"
523                                     " not in group (block %lu)!",
524                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
525                         return 0;
526                 }
527                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
528                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
529                 {
530                         ext2_error (sb, "ext2_check_descriptors",
531                                     "Inode bitmap for group %d"
532                                     " not in group (block %lu)!",
533                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
534                         return 0;
535                 }
536                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
537                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
538                     block + EXT2_BLOCKS_PER_GROUP(sb))
539                 {
540                         ext2_error (sb, "ext2_check_descriptors",
541                                     "Inode table for group %d"
542                                     " not in group (block %lu)!",
543                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
544                         return 0;
545                 }
546                 block += EXT2_BLOCKS_PER_GROUP(sb);
547                 gdp++;
548         }
549         return 1;
550 }
551
552 #define log2(n) ffz(~(n))
553  
554 /*
555  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
556  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
557  * We need to be 1 filesystem block less than the 2^32 sector limit.
558  */
559 static loff_t ext2_max_size(int bits)
560 {
561         loff_t res = EXT2_NDIR_BLOCKS;
562         /* This constant is calculated to be the largest file size for a
563          * dense, 4k-blocksize file such that the total number of
564          * sectors in the file, including data and all indirect blocks,
565          * does not exceed 2^32. */
566         const loff_t upper_limit = 0x1ff7fffd000LL;
567
568         res += 1LL << (bits-2);
569         res += 1LL << (2*(bits-2));
570         res += 1LL << (3*(bits-2));
571         res <<= bits;
572         if (res > upper_limit)
573                 res = upper_limit;
574         return res;
575 }
576
577 static unsigned long descriptor_loc(struct super_block *sb,
578                                     unsigned long logic_sb_block,
579                                     int nr)
580 {
581         struct ext2_sb_info *sbi = EXT2_SB(sb);
582         unsigned long bg, first_data_block, first_meta_bg;
583         int has_super = 0;
584         
585         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
586         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
587
588         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
589             nr < first_meta_bg)
590                 return (logic_sb_block + nr + 1);
591         bg = sbi->s_desc_per_block * nr;
592         if (ext2_bg_has_super(sb, bg))
593                 has_super = 1;
594         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
595 }
596
597 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
598 {
599         struct buffer_head * bh;
600         struct ext2_sb_info * sbi;
601         struct ext2_super_block * es;
602         struct inode *root;
603         unsigned long block;
604         unsigned long sb_block = get_sb_block(&data);
605         unsigned long logic_sb_block;
606         unsigned long offset = 0;
607         unsigned long def_mount_opts;
608         int blocksize = BLOCK_SIZE;
609         int db_count;
610         int i, j;
611         __le32 features;
612
613         sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
614         if (!sbi)
615                 return -ENOMEM;
616         sb->s_fs_info = sbi;
617         memset(sbi, 0, sizeof(*sbi));
618
619         /*
620          * See what the current blocksize for the device is, and
621          * use that as the blocksize.  Otherwise (or if the blocksize
622          * is smaller than the default) use the default.
623          * This is important for devices that have a hardware
624          * sectorsize that is larger than the default.
625          */
626         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
627         if (!blocksize) {
628                 printk ("EXT2-fs: unable to set blocksize\n");
629                 goto failed_sbi;
630         }
631
632         /*
633          * If the superblock doesn't start on a hardware sector boundary,
634          * calculate the offset.  
635          */
636         if (blocksize != BLOCK_SIZE) {
637                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
638                 offset = (sb_block*BLOCK_SIZE) % blocksize;
639         } else {
640                 logic_sb_block = sb_block;
641         }
642
643         if (!(bh = sb_bread(sb, logic_sb_block))) {
644                 printk ("EXT2-fs: unable to read superblock\n");
645                 goto failed_sbi;
646         }
647         /*
648          * Note: s_es must be initialized as soon as possible because
649          *       some ext2 macro-instructions depend on its value
650          */
651         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
652         sbi->s_es = es;
653         sb->s_magic = le16_to_cpu(es->s_magic);
654
655         if (sb->s_magic != EXT2_SUPER_MAGIC)
656                 goto cantfind_ext2;
657
658         /* Set defaults before we parse the mount options */
659         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
660         if (def_mount_opts & EXT2_DEFM_DEBUG)
661                 set_opt(sbi->s_mount_opt, DEBUG);
662         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
663                 set_opt(sbi->s_mount_opt, GRPID);
664         if (def_mount_opts & EXT2_DEFM_UID16)
665                 set_opt(sbi->s_mount_opt, NO_UID32);
666         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
667                 set_opt(sbi->s_mount_opt, XATTR_USER);
668         if (def_mount_opts & EXT2_DEFM_ACL)
669                 set_opt(sbi->s_mount_opt, POSIX_ACL);
670         
671         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
672                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
673         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
674                 set_opt(sbi->s_mount_opt, ERRORS_RO);
675
676         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
677         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
678         
679         if (!parse_options ((char *) data, sbi))
680                 goto failed_mount;
681
682         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
683                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
684                  MS_POSIXACL : 0);
685
686         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
687                                     EXT2_MOUNT_XIP if not */
688
689         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
690             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
691              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
692              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
693                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
694                        "running e2fsck is recommended\n");
695         /*
696          * Check feature flags regardless of the revision level, since we
697          * previously didn't change the revision level when setting the flags,
698          * so there is a chance incompat flags are set on a rev 0 filesystem.
699          */
700         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
701         if (features) {
702                 printk("EXT2-fs: %s: couldn't mount because of "
703                        "unsupported optional features (%x).\n",
704                        sb->s_id, le32_to_cpu(features));
705                 goto failed_mount;
706         }
707         if (!(sb->s_flags & MS_RDONLY) &&
708             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
709                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
710                        "unsupported optional features (%x).\n",
711                        sb->s_id, le32_to_cpu(features));
712                 goto failed_mount;
713         }
714
715         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
716
717         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
718                                   (sb->s_blocksize != blocksize))) {
719                 if (!silent)
720                         printk("XIP: Unsupported blocksize\n");
721                 goto failed_mount;
722         }
723
724         /* If the blocksize doesn't match, re-read the thing.. */
725         if (sb->s_blocksize != blocksize) {
726                 brelse(bh);
727
728                 if (!sb_set_blocksize(sb, blocksize)) {
729                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
730                         goto failed_sbi;
731                 }
732
733                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
734                 offset = (sb_block*BLOCK_SIZE) % blocksize;
735                 bh = sb_bread(sb, logic_sb_block);
736                 if(!bh) {
737                         printk("EXT2-fs: Couldn't read superblock on "
738                                "2nd try.\n");
739                         goto failed_sbi;
740                 }
741                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
742                 sbi->s_es = es;
743                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
744                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
745                         goto failed_mount;
746                 }
747         }
748
749         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
750
751         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
752                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
753                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
754         } else {
755                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
756                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
757                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
758                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
759                     (sbi->s_inode_size > blocksize)) {
760                         printk ("EXT2-fs: unsupported inode size: %d\n",
761                                 sbi->s_inode_size);
762                         goto failed_mount;
763                 }
764         }
765
766         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
767                                    le32_to_cpu(es->s_log_frag_size);
768         if (sbi->s_frag_size == 0)
769                 goto cantfind_ext2;
770         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
771
772         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
773         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
774         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
775
776         if (EXT2_INODE_SIZE(sb) == 0)
777                 goto cantfind_ext2;
778         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
779         if (sbi->s_inodes_per_block == 0)
780                 goto cantfind_ext2;
781         sbi->s_itb_per_group = sbi->s_inodes_per_group /
782                                         sbi->s_inodes_per_block;
783         sbi->s_desc_per_block = sb->s_blocksize /
784                                         sizeof (struct ext2_group_desc);
785         sbi->s_sbh = bh;
786         sbi->s_mount_state = le16_to_cpu(es->s_state);
787         sbi->s_addr_per_block_bits =
788                 log2 (EXT2_ADDR_PER_BLOCK(sb));
789         sbi->s_desc_per_block_bits =
790                 log2 (EXT2_DESC_PER_BLOCK(sb));
791
792         if (sb->s_magic != EXT2_SUPER_MAGIC)
793                 goto cantfind_ext2;
794
795         if (sb->s_blocksize != bh->b_size) {
796                 if (!silent)
797                         printk ("VFS: Unsupported blocksize on dev "
798                                 "%s.\n", sb->s_id);
799                 goto failed_mount;
800         }
801
802         if (sb->s_blocksize != sbi->s_frag_size) {
803                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
804                         sbi->s_frag_size, sb->s_blocksize);
805                 goto failed_mount;
806         }
807
808         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
809                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
810                         sbi->s_blocks_per_group);
811                 goto failed_mount;
812         }
813         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
814                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
815                         sbi->s_frags_per_group);
816                 goto failed_mount;
817         }
818         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
819                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
820                         sbi->s_inodes_per_group);
821                 goto failed_mount;
822         }
823
824         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
825                 goto cantfind_ext2;
826         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
827                                         le32_to_cpu(es->s_first_data_block) +
828                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
829                                        EXT2_BLOCKS_PER_GROUP(sb);
830         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
831                    EXT2_DESC_PER_BLOCK(sb);
832         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
833         if (sbi->s_group_desc == NULL) {
834                 printk ("EXT2-fs: not enough memory\n");
835                 goto failed_mount;
836         }
837         percpu_counter_init(&sbi->s_freeblocks_counter);
838         percpu_counter_init(&sbi->s_freeinodes_counter);
839         percpu_counter_init(&sbi->s_dirs_counter);
840         bgl_lock_init(&sbi->s_blockgroup_lock);
841         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
842                                GFP_KERNEL);
843         if (!sbi->s_debts) {
844                 printk ("EXT2-fs: not enough memory\n");
845                 goto failed_mount_group_desc;
846         }
847         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
848         for (i = 0; i < db_count; i++) {
849                 block = descriptor_loc(sb, logic_sb_block, i);
850                 sbi->s_group_desc[i] = sb_bread(sb, block);
851                 if (!sbi->s_group_desc[i]) {
852                         for (j = 0; j < i; j++)
853                                 brelse (sbi->s_group_desc[j]);
854                         printk ("EXT2-fs: unable to read group descriptors\n");
855                         goto failed_mount_group_desc;
856                 }
857         }
858         if (!ext2_check_descriptors (sb)) {
859                 printk ("EXT2-fs: group descriptors corrupted!\n");
860                 db_count = i;
861                 goto failed_mount2;
862         }
863         sbi->s_gdb_count = db_count;
864         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
865         spin_lock_init(&sbi->s_next_gen_lock);
866         /*
867          * set up enough so that it can read an inode
868          */
869         sb->s_op = &ext2_sops;
870         sb->s_export_op = &ext2_export_ops;
871         sb->s_xattr = ext2_xattr_handlers;
872         root = iget(sb, EXT2_ROOT_INO);
873         sb->s_root = d_alloc_root(root);
874         if (!sb->s_root) {
875                 iput(root);
876                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
877                 goto failed_mount2;
878         }
879         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
880                 dput(sb->s_root);
881                 sb->s_root = NULL;
882                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
883                 goto failed_mount2;
884         }
885         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
886                 ext2_warning(sb, __FUNCTION__,
887                         "mounting ext3 filesystem as ext2");
888         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
889         percpu_counter_mod(&sbi->s_freeblocks_counter,
890                                 ext2_count_free_blocks(sb));
891         percpu_counter_mod(&sbi->s_freeinodes_counter,
892                                 ext2_count_free_inodes(sb));
893         percpu_counter_mod(&sbi->s_dirs_counter,
894                                 ext2_count_dirs(sb));
895         return 0;
896
897 cantfind_ext2:
898         if (!silent)
899                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
900                        sb->s_id);
901         goto failed_mount;
902
903 failed_mount2:
904         for (i = 0; i < db_count; i++)
905                 brelse(sbi->s_group_desc[i]);
906 failed_mount_group_desc:
907         kfree(sbi->s_group_desc);
908         kfree(sbi->s_debts);
909 failed_mount:
910         brelse(bh);
911 failed_sbi:
912         sb->s_fs_info = NULL;
913         kfree(sbi);
914         return -EINVAL;
915 }
916
917 static void ext2_commit_super (struct super_block * sb,
918                                struct ext2_super_block * es)
919 {
920         es->s_wtime = cpu_to_le32(get_seconds());
921         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
922         sb->s_dirt = 0;
923 }
924
925 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
926 {
927         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
928         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
929         es->s_wtime = cpu_to_le32(get_seconds());
930         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
931         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
932         sb->s_dirt = 0;
933 }
934
935 /*
936  * In the second extended file system, it is not necessary to
937  * write the super block since we use a mapping of the
938  * disk super block in a buffer.
939  *
940  * However, this function is still used to set the fs valid
941  * flags to 0.  We need to set this flag to 0 since the fs
942  * may have been checked while mounted and e2fsck may have
943  * set s_state to EXT2_VALID_FS after some corrections.
944  */
945
946 void ext2_write_super (struct super_block * sb)
947 {
948         struct ext2_super_block * es;
949         lock_kernel();
950         if (!(sb->s_flags & MS_RDONLY)) {
951                 es = EXT2_SB(sb)->s_es;
952
953                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
954                         ext2_debug ("setting valid to 0\n");
955                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
956                                                   ~EXT2_VALID_FS);
957                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
958                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
959                         es->s_mtime = cpu_to_le32(get_seconds());
960                         ext2_sync_super(sb, es);
961                 } else
962                         ext2_commit_super (sb, es);
963         }
964         sb->s_dirt = 0;
965         unlock_kernel();
966 }
967
968 static int ext2_remount (struct super_block * sb, int * flags, char * data)
969 {
970         struct ext2_sb_info * sbi = EXT2_SB(sb);
971         struct ext2_super_block * es;
972         unsigned long old_mount_opt = sbi->s_mount_opt;
973         struct ext2_mount_options old_opts;
974         unsigned long old_sb_flags;
975         int err;
976
977         /* Store the old options */
978         old_sb_flags = sb->s_flags;
979         old_opts.s_mount_opt = sbi->s_mount_opt;
980         old_opts.s_resuid = sbi->s_resuid;
981         old_opts.s_resgid = sbi->s_resgid;
982
983         /*
984          * Allow the "check" option to be passed as a remount option.
985          */
986         if (!parse_options (data, sbi)) {
987                 err = -EINVAL;
988                 goto restore_opts;
989         }
990
991         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
992                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
993
994         es = sbi->s_es;
995         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
996             (old_mount_opt & EXT2_MOUNT_XIP)) &&
997             invalidate_inodes(sb))
998                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
999                              "xip remain in cache (no functional problem)");
1000         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1001                 return 0;
1002         if (*flags & MS_RDONLY) {
1003                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1004                     !(sbi->s_mount_state & EXT2_VALID_FS))
1005                         return 0;
1006                 /*
1007                  * OK, we are remounting a valid rw partition rdonly, so set
1008                  * the rdonly flag and then mark the partition as valid again.
1009                  */
1010                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1011                 es->s_mtime = cpu_to_le32(get_seconds());
1012         } else {
1013                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1014                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1015                 if (ret) {
1016                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1017                                "unsupported optional features (%x).\n",
1018                                sb->s_id, le32_to_cpu(ret));
1019                         err = -EROFS;
1020                         goto restore_opts;
1021                 }
1022                 /*
1023                  * Mounting a RDONLY partition read-write, so reread and
1024                  * store the current valid flag.  (It may have been changed
1025                  * by e2fsck since we originally mounted the partition.)
1026                  */
1027                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1028                 if (!ext2_setup_super (sb, es, 0))
1029                         sb->s_flags &= ~MS_RDONLY;
1030         }
1031         ext2_sync_super(sb, es);
1032         return 0;
1033 restore_opts:
1034         sbi->s_mount_opt = old_opts.s_mount_opt;
1035         sbi->s_resuid = old_opts.s_resuid;
1036         sbi->s_resgid = old_opts.s_resgid;
1037         sb->s_flags = old_sb_flags;
1038         return err;
1039 }
1040
1041 static int ext2_statfs (struct super_block * sb, struct kstatfs * buf)
1042 {
1043         struct ext2_sb_info *sbi = EXT2_SB(sb);
1044         unsigned long overhead;
1045         int i;
1046
1047         if (test_opt (sb, MINIX_DF))
1048                 overhead = 0;
1049         else {
1050                 /*
1051                  * Compute the overhead (FS structures)
1052                  */
1053
1054                 /*
1055                  * All of the blocks before first_data_block are
1056                  * overhead
1057                  */
1058                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1059
1060                 /*
1061                  * Add the overhead attributed to the superblock and
1062                  * block group descriptors.  If the sparse superblocks
1063                  * feature is turned on, then not all groups have this.
1064                  */
1065                 for (i = 0; i < sbi->s_groups_count; i++)
1066                         overhead += ext2_bg_has_super(sb, i) +
1067                                 ext2_bg_num_gdb(sb, i);
1068
1069                 /*
1070                  * Every block group has an inode bitmap, a block
1071                  * bitmap, and an inode table.
1072                  */
1073                 overhead += (sbi->s_groups_count *
1074                              (2 + sbi->s_itb_per_group));
1075         }
1076
1077         buf->f_type = EXT2_SUPER_MAGIC;
1078         buf->f_bsize = sb->s_blocksize;
1079         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1080         buf->f_bfree = ext2_count_free_blocks(sb);
1081         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1082         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1083                 buf->f_bavail = 0;
1084         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1085         buf->f_ffree = ext2_count_free_inodes (sb);
1086         buf->f_namelen = EXT2_NAME_LEN;
1087         return 0;
1088 }
1089
1090 static int ext2_get_sb(struct file_system_type *fs_type,
1091         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1092 {
1093         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1094 }
1095
1096 #ifdef CONFIG_QUOTA
1097
1098 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1099  * acquiring the locks... As quota files are never truncated and quota code
1100  * itself serializes the operations (and noone else should touch the files)
1101  * we don't have to be afraid of races */
1102 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1103                                size_t len, loff_t off)
1104 {
1105         struct inode *inode = sb_dqopt(sb)->files[type];
1106         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1107         int err = 0;
1108         int offset = off & (sb->s_blocksize - 1);
1109         int tocopy;
1110         size_t toread;
1111         struct buffer_head tmp_bh;
1112         struct buffer_head *bh;
1113         loff_t i_size = i_size_read(inode);
1114
1115         if (off > i_size)
1116                 return 0;
1117         if (off+len > i_size)
1118                 len = i_size-off;
1119         toread = len;
1120         while (toread > 0) {
1121                 tocopy = sb->s_blocksize - offset < toread ?
1122                                 sb->s_blocksize - offset : toread;
1123
1124                 tmp_bh.b_state = 0;
1125                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1126                 if (err)
1127                         return err;
1128                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1129                         memset(data, 0, tocopy);
1130                 else {
1131                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1132                         if (!bh)
1133                                 return -EIO;
1134                         memcpy(data, bh->b_data+offset, tocopy);
1135                         brelse(bh);
1136                 }
1137                 offset = 0;
1138                 toread -= tocopy;
1139                 data += tocopy;
1140                 blk++;
1141         }
1142         return len;
1143 }
1144
1145 /* Write to quotafile */
1146 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1147                                 const char *data, size_t len, loff_t off)
1148 {
1149         struct inode *inode = sb_dqopt(sb)->files[type];
1150         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1151         int err = 0;
1152         int offset = off & (sb->s_blocksize - 1);
1153         int tocopy;
1154         size_t towrite = len;
1155         struct buffer_head tmp_bh;
1156         struct buffer_head *bh;
1157
1158         mutex_lock(&inode->i_mutex);
1159         while (towrite > 0) {
1160                 tocopy = sb->s_blocksize - offset < towrite ?
1161                                 sb->s_blocksize - offset : towrite;
1162
1163                 tmp_bh.b_state = 0;
1164                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1165                 if (err)
1166                         goto out;
1167                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1168                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1169                 else
1170                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1171                 if (!bh) {
1172                         err = -EIO;
1173                         goto out;
1174                 }
1175                 lock_buffer(bh);
1176                 memcpy(bh->b_data+offset, data, tocopy);
1177                 flush_dcache_page(bh->b_page);
1178                 set_buffer_uptodate(bh);
1179                 mark_buffer_dirty(bh);
1180                 unlock_buffer(bh);
1181                 brelse(bh);
1182                 offset = 0;
1183                 towrite -= tocopy;
1184                 data += tocopy;
1185                 blk++;
1186         }
1187 out:
1188         if (len == towrite)
1189                 return err;
1190         if (inode->i_size < off+len-towrite)
1191                 i_size_write(inode, off+len-towrite);
1192         inode->i_version++;
1193         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1194         mark_inode_dirty(inode);
1195         mutex_unlock(&inode->i_mutex);
1196         return len - towrite;
1197 }
1198
1199 #endif
1200
1201 static struct file_system_type ext2_fs_type = {
1202         .owner          = THIS_MODULE,
1203         .name           = "ext2",
1204         .get_sb         = ext2_get_sb,
1205         .kill_sb        = kill_block_super,
1206         .fs_flags       = FS_REQUIRES_DEV,
1207 };
1208
1209 static int __init init_ext2_fs(void)
1210 {
1211         int err = init_ext2_xattr();
1212         if (err)
1213                 return err;
1214         err = init_inodecache();
1215         if (err)
1216                 goto out1;
1217         err = register_filesystem(&ext2_fs_type);
1218         if (err)
1219                 goto out;
1220         return 0;
1221 out:
1222         destroy_inodecache();
1223 out1:
1224         exit_ext2_xattr();
1225         return err;
1226 }
1227
1228 static void __exit exit_ext2_fs(void)
1229 {
1230         unregister_filesystem(&ext2_fs_type);
1231         destroy_inodecache();
1232         exit_ext2_xattr();
1233 }
1234
1235 module_init(init_ext2_fs)
1236 module_exit(exit_ext2_fs)