681dea8f9532ee744932bdc6fa9762360d892b45
[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/module.h>
20 #include <linux/string.h>
21 #include <linux/fs.h>
22 #include <linux/slab.h>
23 #include <linux/init.h>
24 #include <linux/blkdev.h>
25 #include <linux/parser.h>
26 #include <linux/random.h>
27 #include <linux/buffer_head.h>
28 #include <linux/smp_lock.h>
29 #include <linux/vfs.h>
30 #include <linux/seq_file.h>
31 #include <linux/mount.h>
32 #include <asm/uaccess.h>
33 #include "ext2.h"
34 #include "xattr.h"
35 #include "acl.h"
36 #include "xip.h"
37
38 static void ext2_sync_super(struct super_block *sb,
39                             struct ext2_super_block *es);
40 static int ext2_remount (struct super_block * sb, int * flags, char * data);
41 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
42
43 void ext2_error (struct super_block * sb, const char * function,
44                  const char * fmt, ...)
45 {
46         va_list args;
47         struct ext2_sb_info *sbi = EXT2_SB(sb);
48         struct ext2_super_block *es = sbi->s_es;
49
50         if (!(sb->s_flags & MS_RDONLY)) {
51                 sbi->s_mount_state |= EXT2_ERROR_FS;
52                 es->s_state =
53                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
54                 ext2_sync_super(sb, es);
55         }
56
57         va_start(args, fmt);
58         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
59         vprintk(fmt, args);
60         printk("\n");
61         va_end(args);
62
63         if (test_opt(sb, ERRORS_PANIC))
64                 panic("EXT2-fs panic from previous error\n");
65         if (test_opt(sb, ERRORS_RO)) {
66                 printk("Remounting filesystem read-only\n");
67                 sb->s_flags |= MS_RDONLY;
68         }
69 }
70
71 void ext2_warning (struct super_block * sb, const char * function,
72                    const char * fmt, ...)
73 {
74         va_list args;
75
76         va_start(args, fmt);
77         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
78                sb->s_id, function);
79         vprintk(fmt, args);
80         printk("\n");
81         va_end(args);
82 }
83
84 void ext2_update_dynamic_rev(struct super_block *sb)
85 {
86         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
87
88         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
89                 return;
90
91         ext2_warning(sb, __FUNCTION__,
92                      "updating to rev %d because of new feature flag, "
93                      "running e2fsck is recommended",
94                      EXT2_DYNAMIC_REV);
95
96         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
97         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
98         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
99         /* leave es->s_feature_*compat flags alone */
100         /* es->s_uuid will be set by e2fsck if empty */
101
102         /*
103          * The rest of the superblock fields should be zero, and if not it
104          * means they are likely already in use, so leave them alone.  We
105          * can leave it up to e2fsck to clean up any inconsistencies there.
106          */
107 }
108
109 static void ext2_put_super (struct super_block * sb)
110 {
111         int db_count;
112         int i;
113         struct ext2_sb_info *sbi = EXT2_SB(sb);
114
115         ext2_xattr_put_super(sb);
116         if (!(sb->s_flags & MS_RDONLY)) {
117                 struct ext2_super_block *es = sbi->s_es;
118
119                 es->s_state = cpu_to_le16(sbi->s_mount_state);
120                 ext2_sync_super(sb, es);
121         }
122         db_count = sbi->s_gdb_count;
123         for (i = 0; i < db_count; i++)
124                 if (sbi->s_group_desc[i])
125                         brelse (sbi->s_group_desc[i]);
126         kfree(sbi->s_group_desc);
127         kfree(sbi->s_debts);
128         percpu_counter_destroy(&sbi->s_freeblocks_counter);
129         percpu_counter_destroy(&sbi->s_freeinodes_counter);
130         percpu_counter_destroy(&sbi->s_dirs_counter);
131         brelse (sbi->s_sbh);
132         sb->s_fs_info = NULL;
133         kfree(sbi);
134
135         return;
136 }
137
138 static kmem_cache_t * ext2_inode_cachep;
139
140 static struct inode *ext2_alloc_inode(struct super_block *sb)
141 {
142         struct ext2_inode_info *ei;
143         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL);
144         if (!ei)
145                 return NULL;
146 #ifdef CONFIG_EXT2_FS_POSIX_ACL
147         ei->i_acl = EXT2_ACL_NOT_CACHED;
148         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
149 #endif
150         ei->vfs_inode.i_version = 1;
151         return &ei->vfs_inode;
152 }
153
154 static void ext2_destroy_inode(struct inode *inode)
155 {
156         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
157 }
158
159 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
160 {
161         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
162
163         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
164             SLAB_CTOR_CONSTRUCTOR) {
165                 rwlock_init(&ei->i_meta_lock);
166 #ifdef CONFIG_EXT2_FS_XATTR
167                 init_rwsem(&ei->xattr_sem);
168 #endif
169                 inode_init_once(&ei->vfs_inode);
170         }
171 }
172  
173 static int init_inodecache(void)
174 {
175         ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
176                                              sizeof(struct ext2_inode_info),
177                                              0, (SLAB_RECLAIM_ACCOUNT|
178                                                 SLAB_MEM_SPREAD),
179                                              init_once, NULL);
180         if (ext2_inode_cachep == NULL)
181                 return -ENOMEM;
182         return 0;
183 }
184
185 static void destroy_inodecache(void)
186 {
187         if (kmem_cache_destroy(ext2_inode_cachep))
188                 printk(KERN_INFO "ext2_inode_cache: not all structures were freed\n");
189 }
190
191 static void ext2_clear_inode(struct inode *inode)
192 {
193 #ifdef CONFIG_EXT2_FS_POSIX_ACL
194         struct ext2_inode_info *ei = EXT2_I(inode);
195
196         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
197                 posix_acl_release(ei->i_acl);
198                 ei->i_acl = EXT2_ACL_NOT_CACHED;
199         }
200         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
201                 posix_acl_release(ei->i_default_acl);
202                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
203         }
204 #endif
205 }
206
207 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
208 {
209         struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
210
211         if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
212                 seq_puts(seq, ",grpid");
213
214 #if defined(CONFIG_QUOTA)
215         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
216                 seq_puts(seq, ",usrquota");
217
218         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
219                 seq_puts(seq, ",grpquota");
220 #endif
221
222 #if defined(CONFIG_EXT2_FS_XIP)
223         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
224                 seq_puts(seq, ",xip");
225 #endif
226
227         return 0;
228 }
229
230 #ifdef CONFIG_QUOTA
231 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
232 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
233 #endif
234
235 static struct super_operations ext2_sops = {
236         .alloc_inode    = ext2_alloc_inode,
237         .destroy_inode  = ext2_destroy_inode,
238         .read_inode     = ext2_read_inode,
239         .write_inode    = ext2_write_inode,
240         .put_inode      = ext2_put_inode,
241         .delete_inode   = ext2_delete_inode,
242         .put_super      = ext2_put_super,
243         .write_super    = ext2_write_super,
244         .statfs         = ext2_statfs,
245         .remount_fs     = ext2_remount,
246         .clear_inode    = ext2_clear_inode,
247         .show_options   = ext2_show_options,
248 #ifdef CONFIG_QUOTA
249         .quota_read     = ext2_quota_read,
250         .quota_write    = ext2_quota_write,
251 #endif
252 };
253
254 /* Yes, most of these are left as NULL!!
255  * A NULL value implies the default, which works with ext2-like file
256  * systems, but can be improved upon.
257  * Currently only get_parent is required.
258  */
259 static struct export_operations ext2_export_ops = {
260         .get_parent = ext2_get_parent,
261 };
262
263 static unsigned long get_sb_block(void **data)
264 {
265         unsigned long   sb_block;
266         char            *options = (char *) *data;
267
268         if (!options || strncmp(options, "sb=", 3) != 0)
269                 return 1;       /* Default location */
270         options += 3;
271         sb_block = simple_strtoul(options, &options, 0);
272         if (*options && *options != ',') {
273                 printk("EXT2-fs: Invalid sb specification: %s\n",
274                        (char *) *data);
275                 return 1;
276         }
277         if (*options == ',')
278                 options++;
279         *data = (void *) options;
280         return sb_block;
281 }
282
283 enum {
284         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
285         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
286         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
287         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
288         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
289         Opt_usrquota, Opt_grpquota
290 };
291
292 static match_table_t tokens = {
293         {Opt_bsd_df, "bsddf"},
294         {Opt_minix_df, "minixdf"},
295         {Opt_grpid, "grpid"},
296         {Opt_grpid, "bsdgroups"},
297         {Opt_nogrpid, "nogrpid"},
298         {Opt_nogrpid, "sysvgroups"},
299         {Opt_resgid, "resgid=%u"},
300         {Opt_resuid, "resuid=%u"},
301         {Opt_sb, "sb=%u"},
302         {Opt_err_cont, "errors=continue"},
303         {Opt_err_panic, "errors=panic"},
304         {Opt_err_ro, "errors=remount-ro"},
305         {Opt_nouid32, "nouid32"},
306         {Opt_nocheck, "check=none"},
307         {Opt_nocheck, "nocheck"},
308         {Opt_debug, "debug"},
309         {Opt_oldalloc, "oldalloc"},
310         {Opt_orlov, "orlov"},
311         {Opt_nobh, "nobh"},
312         {Opt_user_xattr, "user_xattr"},
313         {Opt_nouser_xattr, "nouser_xattr"},
314         {Opt_acl, "acl"},
315         {Opt_noacl, "noacl"},
316         {Opt_xip, "xip"},
317         {Opt_grpquota, "grpquota"},
318         {Opt_ignore, "noquota"},
319         {Opt_quota, "quota"},
320         {Opt_usrquota, "usrquota"},
321         {Opt_err, NULL}
322 };
323
324 static int parse_options (char * options,
325                           struct ext2_sb_info *sbi)
326 {
327         char * p;
328         substring_t args[MAX_OPT_ARGS];
329         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
330         int option;
331
332         if (!options)
333                 return 1;
334
335         while ((p = strsep (&options, ",")) != NULL) {
336                 int token;
337                 if (!*p)
338                         continue;
339
340                 token = match_token(p, tokens, args);
341                 switch (token) {
342                 case Opt_bsd_df:
343                         clear_opt (sbi->s_mount_opt, MINIX_DF);
344                         break;
345                 case Opt_minix_df:
346                         set_opt (sbi->s_mount_opt, MINIX_DF);
347                         break;
348                 case Opt_grpid:
349                         set_opt (sbi->s_mount_opt, GRPID);
350                         break;
351                 case Opt_nogrpid:
352                         clear_opt (sbi->s_mount_opt, GRPID);
353                         break;
354                 case Opt_resuid:
355                         if (match_int(&args[0], &option))
356                                 return 0;
357                         sbi->s_resuid = option;
358                         break;
359                 case Opt_resgid:
360                         if (match_int(&args[0], &option))
361                                 return 0;
362                         sbi->s_resgid = option;
363                         break;
364                 case Opt_sb:
365                         /* handled by get_sb_block() instead of here */
366                         /* *sb_block = match_int(&args[0]); */
367                         break;
368                 case Opt_err_panic:
369                         kind = EXT2_MOUNT_ERRORS_PANIC;
370                         break;
371                 case Opt_err_ro:
372                         kind = EXT2_MOUNT_ERRORS_RO;
373                         break;
374                 case Opt_err_cont:
375                         kind = EXT2_MOUNT_ERRORS_CONT;
376                         break;
377                 case Opt_nouid32:
378                         set_opt (sbi->s_mount_opt, NO_UID32);
379                         break;
380                 case Opt_nocheck:
381                         clear_opt (sbi->s_mount_opt, CHECK);
382                         break;
383                 case Opt_debug:
384                         set_opt (sbi->s_mount_opt, DEBUG);
385                         break;
386                 case Opt_oldalloc:
387                         set_opt (sbi->s_mount_opt, OLDALLOC);
388                         break;
389                 case Opt_orlov:
390                         clear_opt (sbi->s_mount_opt, OLDALLOC);
391                         break;
392                 case Opt_nobh:
393                         set_opt (sbi->s_mount_opt, NOBH);
394                         break;
395 #ifdef CONFIG_EXT2_FS_XATTR
396                 case Opt_user_xattr:
397                         set_opt (sbi->s_mount_opt, XATTR_USER);
398                         break;
399                 case Opt_nouser_xattr:
400                         clear_opt (sbi->s_mount_opt, XATTR_USER);
401                         break;
402 #else
403                 case Opt_user_xattr:
404                 case Opt_nouser_xattr:
405                         printk("EXT2 (no)user_xattr options not supported\n");
406                         break;
407 #endif
408 #ifdef CONFIG_EXT2_FS_POSIX_ACL
409                 case Opt_acl:
410                         set_opt(sbi->s_mount_opt, POSIX_ACL);
411                         break;
412                 case Opt_noacl:
413                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
414                         break;
415 #else
416                 case Opt_acl:
417                 case Opt_noacl:
418                         printk("EXT2 (no)acl options not supported\n");
419                         break;
420 #endif
421                 case Opt_xip:
422 #ifdef CONFIG_EXT2_FS_XIP
423                         set_opt (sbi->s_mount_opt, XIP);
424 #else
425                         printk("EXT2 xip option not supported\n");
426 #endif
427                         break;
428
429 #if defined(CONFIG_QUOTA)
430                 case Opt_quota:
431                 case Opt_usrquota:
432                         set_opt(sbi->s_mount_opt, USRQUOTA);
433                         break;
434
435                 case Opt_grpquota:
436                         set_opt(sbi->s_mount_opt, GRPQUOTA);
437                         break;
438 #else
439                 case Opt_quota:
440                 case Opt_usrquota:
441                 case Opt_grpquota:
442                         printk(KERN_ERR
443                                 "EXT2-fs: quota operations not supported.\n");
444
445                         break;
446 #endif
447
448                 case Opt_ignore:
449                         break;
450                 default:
451                         return 0;
452                 }
453         }
454         sbi->s_mount_opt |= kind;
455         return 1;
456 }
457
458 static int ext2_setup_super (struct super_block * sb,
459                               struct ext2_super_block * es,
460                               int read_only)
461 {
462         int res = 0;
463         struct ext2_sb_info *sbi = EXT2_SB(sb);
464
465         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
466                 printk ("EXT2-fs warning: revision level too high, "
467                         "forcing read-only mode\n");
468                 res = MS_RDONLY;
469         }
470         if (read_only)
471                 return res;
472         if (!(sbi->s_mount_state & EXT2_VALID_FS))
473                 printk ("EXT2-fs warning: mounting unchecked fs, "
474                         "running e2fsck is recommended\n");
475         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
476                 printk ("EXT2-fs warning: mounting fs with errors, "
477                         "running e2fsck is recommended\n");
478         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
479                  le16_to_cpu(es->s_mnt_count) >=
480                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
481                 printk ("EXT2-fs warning: maximal mount count reached, "
482                         "running e2fsck is recommended\n");
483         else if (le32_to_cpu(es->s_checkinterval) &&
484                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
485                 printk ("EXT2-fs warning: checktime reached, "
486                         "running e2fsck is recommended\n");
487         if (!le16_to_cpu(es->s_max_mnt_count))
488                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
489         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
490         ext2_write_super(sb);
491         if (test_opt (sb, DEBUG))
492                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
493                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
494                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
495                         sbi->s_frag_size,
496                         sbi->s_groups_count,
497                         EXT2_BLOCKS_PER_GROUP(sb),
498                         EXT2_INODES_PER_GROUP(sb),
499                         sbi->s_mount_opt);
500         return res;
501 }
502
503 static int ext2_check_descriptors (struct super_block * sb)
504 {
505         int i;
506         int desc_block = 0;
507         struct ext2_sb_info *sbi = EXT2_SB(sb);
508         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
509         struct ext2_group_desc * gdp = NULL;
510
511         ext2_debug ("Checking group descriptors");
512
513         for (i = 0; i < sbi->s_groups_count; i++)
514         {
515                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
516                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
517                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
518                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
519                 {
520                         ext2_error (sb, "ext2_check_descriptors",
521                                     "Block bitmap for group %d"
522                                     " not in group (block %lu)!",
523                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
524                         return 0;
525                 }
526                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
527                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
528                 {
529                         ext2_error (sb, "ext2_check_descriptors",
530                                     "Inode bitmap for group %d"
531                                     " not in group (block %lu)!",
532                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
533                         return 0;
534                 }
535                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
536                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
537                     block + EXT2_BLOCKS_PER_GROUP(sb))
538                 {
539                         ext2_error (sb, "ext2_check_descriptors",
540                                     "Inode table for group %d"
541                                     " not in group (block %lu)!",
542                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
543                         return 0;
544                 }
545                 block += EXT2_BLOCKS_PER_GROUP(sb);
546                 gdp++;
547         }
548         return 1;
549 }
550
551 #define log2(n) ffz(~(n))
552  
553 /*
554  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
555  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
556  * We need to be 1 filesystem block less than the 2^32 sector limit.
557  */
558 static loff_t ext2_max_size(int bits)
559 {
560         loff_t res = EXT2_NDIR_BLOCKS;
561         /* This constant is calculated to be the largest file size for a
562          * dense, 4k-blocksize file such that the total number of
563          * sectors in the file, including data and all indirect blocks,
564          * does not exceed 2^32. */
565         const loff_t upper_limit = 0x1ff7fffd000LL;
566
567         res += 1LL << (bits-2);
568         res += 1LL << (2*(bits-2));
569         res += 1LL << (3*(bits-2));
570         res <<= bits;
571         if (res > upper_limit)
572                 res = upper_limit;
573         return res;
574 }
575
576 static unsigned long descriptor_loc(struct super_block *sb,
577                                     unsigned long logic_sb_block,
578                                     int nr)
579 {
580         struct ext2_sb_info *sbi = EXT2_SB(sb);
581         unsigned long bg, first_data_block, first_meta_bg;
582         int has_super = 0;
583         
584         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
585         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
586
587         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
588             nr < first_meta_bg)
589                 return (logic_sb_block + nr + 1);
590         bg = sbi->s_desc_per_block * nr;
591         if (ext2_bg_has_super(sb, bg))
592                 has_super = 1;
593         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
594 }
595
596 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
597 {
598         struct buffer_head * bh;
599         struct ext2_sb_info * sbi;
600         struct ext2_super_block * es;
601         struct inode *root;
602         unsigned long block;
603         unsigned long sb_block = get_sb_block(&data);
604         unsigned long logic_sb_block;
605         unsigned long offset = 0;
606         unsigned long def_mount_opts;
607         int blocksize = BLOCK_SIZE;
608         int db_count;
609         int i, j;
610         __le32 features;
611
612         sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
613         if (!sbi)
614                 return -ENOMEM;
615         sb->s_fs_info = sbi;
616         memset(sbi, 0, sizeof(*sbi));
617
618         /*
619          * See what the current blocksize for the device is, and
620          * use that as the blocksize.  Otherwise (or if the blocksize
621          * is smaller than the default) use the default.
622          * This is important for devices that have a hardware
623          * sectorsize that is larger than the default.
624          */
625         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
626         if (!blocksize) {
627                 printk ("EXT2-fs: unable to set blocksize\n");
628                 goto failed_sbi;
629         }
630
631         /*
632          * If the superblock doesn't start on a hardware sector boundary,
633          * calculate the offset.  
634          */
635         if (blocksize != BLOCK_SIZE) {
636                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
637                 offset = (sb_block*BLOCK_SIZE) % blocksize;
638         } else {
639                 logic_sb_block = sb_block;
640         }
641
642         if (!(bh = sb_bread(sb, logic_sb_block))) {
643                 printk ("EXT2-fs: unable to read superblock\n");
644                 goto failed_sbi;
645         }
646         /*
647          * Note: s_es must be initialized as soon as possible because
648          *       some ext2 macro-instructions depend on its value
649          */
650         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
651         sbi->s_es = es;
652         sb->s_magic = le16_to_cpu(es->s_magic);
653
654         if (sb->s_magic != EXT2_SUPER_MAGIC)
655                 goto cantfind_ext2;
656
657         /* Set defaults before we parse the mount options */
658         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
659         if (def_mount_opts & EXT2_DEFM_DEBUG)
660                 set_opt(sbi->s_mount_opt, DEBUG);
661         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
662                 set_opt(sbi->s_mount_opt, GRPID);
663         if (def_mount_opts & EXT2_DEFM_UID16)
664                 set_opt(sbi->s_mount_opt, NO_UID32);
665         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
666                 set_opt(sbi->s_mount_opt, XATTR_USER);
667         if (def_mount_opts & EXT2_DEFM_ACL)
668                 set_opt(sbi->s_mount_opt, POSIX_ACL);
669         
670         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
671                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
672         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
673                 set_opt(sbi->s_mount_opt, ERRORS_RO);
674
675         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
676         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
677         
678         if (!parse_options ((char *) data, sbi))
679                 goto failed_mount;
680
681         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
682                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
683                  MS_POSIXACL : 0);
684
685         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
686                                     EXT2_MOUNT_XIP if not */
687
688         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
689             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
690              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
691              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
692                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
693                        "running e2fsck is recommended\n");
694         /*
695          * Check feature flags regardless of the revision level, since we
696          * previously didn't change the revision level when setting the flags,
697          * so there is a chance incompat flags are set on a rev 0 filesystem.
698          */
699         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
700         if (features) {
701                 printk("EXT2-fs: %s: couldn't mount because of "
702                        "unsupported optional features (%x).\n",
703                        sb->s_id, le32_to_cpu(features));
704                 goto failed_mount;
705         }
706         if (!(sb->s_flags & MS_RDONLY) &&
707             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
708                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
709                        "unsupported optional features (%x).\n",
710                        sb->s_id, le32_to_cpu(features));
711                 goto failed_mount;
712         }
713
714         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
715
716         if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
717                                   (sb->s_blocksize != blocksize))) {
718                 if (!silent)
719                         printk("XIP: Unsupported blocksize\n");
720                 goto failed_mount;
721         }
722
723         /* If the blocksize doesn't match, re-read the thing.. */
724         if (sb->s_blocksize != blocksize) {
725                 brelse(bh);
726
727                 if (!sb_set_blocksize(sb, blocksize)) {
728                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
729                         goto failed_sbi;
730                 }
731
732                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
733                 offset = (sb_block*BLOCK_SIZE) % blocksize;
734                 bh = sb_bread(sb, logic_sb_block);
735                 if(!bh) {
736                         printk("EXT2-fs: Couldn't read superblock on "
737                                "2nd try.\n");
738                         goto failed_sbi;
739                 }
740                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
741                 sbi->s_es = es;
742                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
743                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
744                         goto failed_mount;
745                 }
746         }
747
748         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
749
750         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
751                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
752                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
753         } else {
754                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
755                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
756                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
757                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
758                     (sbi->s_inode_size > blocksize)) {
759                         printk ("EXT2-fs: unsupported inode size: %d\n",
760                                 sbi->s_inode_size);
761                         goto failed_mount;
762                 }
763         }
764
765         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
766                                    le32_to_cpu(es->s_log_frag_size);
767         if (sbi->s_frag_size == 0)
768                 goto cantfind_ext2;
769         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
770
771         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
772         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
773         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
774
775         if (EXT2_INODE_SIZE(sb) == 0)
776                 goto cantfind_ext2;
777         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
778         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
779                 goto cantfind_ext2;
780         sbi->s_itb_per_group = sbi->s_inodes_per_group /
781                                         sbi->s_inodes_per_block;
782         sbi->s_desc_per_block = sb->s_blocksize /
783                                         sizeof (struct ext2_group_desc);
784         sbi->s_sbh = bh;
785         sbi->s_mount_state = le16_to_cpu(es->s_state);
786         sbi->s_addr_per_block_bits =
787                 log2 (EXT2_ADDR_PER_BLOCK(sb));
788         sbi->s_desc_per_block_bits =
789                 log2 (EXT2_DESC_PER_BLOCK(sb));
790
791         if (sb->s_magic != EXT2_SUPER_MAGIC)
792                 goto cantfind_ext2;
793
794         if (sb->s_blocksize != bh->b_size) {
795                 if (!silent)
796                         printk ("VFS: Unsupported blocksize on dev "
797                                 "%s.\n", sb->s_id);
798                 goto failed_mount;
799         }
800
801         if (sb->s_blocksize != sbi->s_frag_size) {
802                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
803                         sbi->s_frag_size, sb->s_blocksize);
804                 goto failed_mount;
805         }
806
807         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
808                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
809                         sbi->s_blocks_per_group);
810                 goto failed_mount;
811         }
812         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
813                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
814                         sbi->s_frags_per_group);
815                 goto failed_mount;
816         }
817         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
818                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
819                         sbi->s_inodes_per_group);
820                 goto failed_mount;
821         }
822
823         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
824                 goto cantfind_ext2;
825         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
826                                         le32_to_cpu(es->s_first_data_block) +
827                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
828                                        EXT2_BLOCKS_PER_GROUP(sb);
829         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
830                    EXT2_DESC_PER_BLOCK(sb);
831         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
832         if (sbi->s_group_desc == NULL) {
833                 printk ("EXT2-fs: not enough memory\n");
834                 goto failed_mount;
835         }
836         bgl_lock_init(&sbi->s_blockgroup_lock);
837         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
838                                GFP_KERNEL);
839         if (!sbi->s_debts) {
840                 printk ("EXT2-fs: not enough memory\n");
841                 goto failed_mount_group_desc;
842         }
843         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
844         for (i = 0; i < db_count; i++) {
845                 block = descriptor_loc(sb, logic_sb_block, i);
846                 sbi->s_group_desc[i] = sb_bread(sb, block);
847                 if (!sbi->s_group_desc[i]) {
848                         for (j = 0; j < i; j++)
849                                 brelse (sbi->s_group_desc[j]);
850                         printk ("EXT2-fs: unable to read group descriptors\n");
851                         goto failed_mount_group_desc;
852                 }
853         }
854         if (!ext2_check_descriptors (sb)) {
855                 printk ("EXT2-fs: group descriptors corrupted!\n");
856                 goto failed_mount2;
857         }
858         sbi->s_gdb_count = db_count;
859         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
860         spin_lock_init(&sbi->s_next_gen_lock);
861
862         percpu_counter_init(&sbi->s_freeblocks_counter,
863                                 ext2_count_free_blocks(sb));
864         percpu_counter_init(&sbi->s_freeinodes_counter,
865                                 ext2_count_free_inodes(sb));
866         percpu_counter_init(&sbi->s_dirs_counter,
867                                 ext2_count_dirs(sb));
868         /*
869          * set up enough so that it can read an inode
870          */
871         sb->s_op = &ext2_sops;
872         sb->s_export_op = &ext2_export_ops;
873         sb->s_xattr = ext2_xattr_handlers;
874         root = iget(sb, EXT2_ROOT_INO);
875         sb->s_root = d_alloc_root(root);
876         if (!sb->s_root) {
877                 iput(root);
878                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
879                 goto failed_mount3;
880         }
881         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
882                 dput(sb->s_root);
883                 sb->s_root = NULL;
884                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
885                 goto failed_mount3;
886         }
887         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
888                 ext2_warning(sb, __FUNCTION__,
889                         "mounting ext3 filesystem as ext2");
890         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
891         return 0;
892
893 cantfind_ext2:
894         if (!silent)
895                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
896                        sb->s_id);
897         goto failed_mount;
898 failed_mount3:
899         percpu_counter_destroy(&sbi->s_freeblocks_counter);
900         percpu_counter_destroy(&sbi->s_freeinodes_counter);
901         percpu_counter_destroy(&sbi->s_dirs_counter);
902 failed_mount2:
903         for (i = 0; i < db_count; i++)
904                 brelse(sbi->s_group_desc[i]);
905 failed_mount_group_desc:
906         kfree(sbi->s_group_desc);
907         kfree(sbi->s_debts);
908 failed_mount:
909         brelse(bh);
910 failed_sbi:
911         sb->s_fs_info = NULL;
912         kfree(sbi);
913         return -EINVAL;
914 }
915
916 static void ext2_commit_super (struct super_block * sb,
917                                struct ext2_super_block * es)
918 {
919         es->s_wtime = cpu_to_le32(get_seconds());
920         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
921         sb->s_dirt = 0;
922 }
923
924 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
925 {
926         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
927         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
928         es->s_wtime = cpu_to_le32(get_seconds());
929         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
930         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
931         sb->s_dirt = 0;
932 }
933
934 /*
935  * In the second extended file system, it is not necessary to
936  * write the super block since we use a mapping of the
937  * disk super block in a buffer.
938  *
939  * However, this function is still used to set the fs valid
940  * flags to 0.  We need to set this flag to 0 since the fs
941  * may have been checked while mounted and e2fsck may have
942  * set s_state to EXT2_VALID_FS after some corrections.
943  */
944
945 void ext2_write_super (struct super_block * sb)
946 {
947         struct ext2_super_block * es;
948         lock_kernel();
949         if (!(sb->s_flags & MS_RDONLY)) {
950                 es = EXT2_SB(sb)->s_es;
951
952                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
953                         ext2_debug ("setting valid to 0\n");
954                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
955                                                   ~EXT2_VALID_FS);
956                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
957                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
958                         es->s_mtime = cpu_to_le32(get_seconds());
959                         ext2_sync_super(sb, es);
960                 } else
961                         ext2_commit_super (sb, es);
962         }
963         sb->s_dirt = 0;
964         unlock_kernel();
965 }
966
967 static int ext2_remount (struct super_block * sb, int * flags, char * data)
968 {
969         struct ext2_sb_info * sbi = EXT2_SB(sb);
970         struct ext2_super_block * es;
971         unsigned long old_mount_opt = sbi->s_mount_opt;
972         struct ext2_mount_options old_opts;
973         unsigned long old_sb_flags;
974         int err;
975
976         /* Store the old options */
977         old_sb_flags = sb->s_flags;
978         old_opts.s_mount_opt = sbi->s_mount_opt;
979         old_opts.s_resuid = sbi->s_resuid;
980         old_opts.s_resgid = sbi->s_resgid;
981
982         /*
983          * Allow the "check" option to be passed as a remount option.
984          */
985         if (!parse_options (data, sbi)) {
986                 err = -EINVAL;
987                 goto restore_opts;
988         }
989
990         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
991                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
992
993         es = sbi->s_es;
994         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
995             (old_mount_opt & EXT2_MOUNT_XIP)) &&
996             invalidate_inodes(sb))
997                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
998                              "xip remain in cache (no functional problem)");
999         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1000                 return 0;
1001         if (*flags & MS_RDONLY) {
1002                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1003                     !(sbi->s_mount_state & EXT2_VALID_FS))
1004                         return 0;
1005                 /*
1006                  * OK, we are remounting a valid rw partition rdonly, so set
1007                  * the rdonly flag and then mark the partition as valid again.
1008                  */
1009                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1010                 es->s_mtime = cpu_to_le32(get_seconds());
1011         } else {
1012                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1013                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1014                 if (ret) {
1015                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1016                                "unsupported optional features (%x).\n",
1017                                sb->s_id, le32_to_cpu(ret));
1018                         err = -EROFS;
1019                         goto restore_opts;
1020                 }
1021                 /*
1022                  * Mounting a RDONLY partition read-write, so reread and
1023                  * store the current valid flag.  (It may have been changed
1024                  * by e2fsck since we originally mounted the partition.)
1025                  */
1026                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1027                 if (!ext2_setup_super (sb, es, 0))
1028                         sb->s_flags &= ~MS_RDONLY;
1029         }
1030         ext2_sync_super(sb, es);
1031         return 0;
1032 restore_opts:
1033         sbi->s_mount_opt = old_opts.s_mount_opt;
1034         sbi->s_resuid = old_opts.s_resuid;
1035         sbi->s_resgid = old_opts.s_resgid;
1036         sb->s_flags = old_sb_flags;
1037         return err;
1038 }
1039
1040 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1041 {
1042         struct super_block *sb = dentry->d_sb;
1043         struct ext2_sb_info *sbi = EXT2_SB(sb);
1044         unsigned long overhead;
1045         int i;
1046
1047         lock_super(sb);
1048         if (test_opt (sb, MINIX_DF))
1049                 overhead = 0;
1050         else {
1051                 /*
1052                  * Compute the overhead (FS structures)
1053                  */
1054
1055                 /*
1056                  * All of the blocks before first_data_block are
1057                  * overhead
1058                  */
1059                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1060
1061                 /*
1062                  * Add the overhead attributed to the superblock and
1063                  * block group descriptors.  If the sparse superblocks
1064                  * feature is turned on, then not all groups have this.
1065                  */
1066                 for (i = 0; i < sbi->s_groups_count; i++)
1067                         overhead += ext2_bg_has_super(sb, i) +
1068                                 ext2_bg_num_gdb(sb, i);
1069
1070                 /*
1071                  * Every block group has an inode bitmap, a block
1072                  * bitmap, and an inode table.
1073                  */
1074                 overhead += (sbi->s_groups_count *
1075                              (2 + sbi->s_itb_per_group));
1076         }
1077
1078         buf->f_type = EXT2_SUPER_MAGIC;
1079         buf->f_bsize = sb->s_blocksize;
1080         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1081         buf->f_bfree = ext2_count_free_blocks(sb);
1082         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1083         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1084                 buf->f_bavail = 0;
1085         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1086         buf->f_ffree = ext2_count_free_inodes (sb);
1087         buf->f_namelen = EXT2_NAME_LEN;
1088         unlock_super(sb);
1089         return 0;
1090 }
1091
1092 static int ext2_get_sb(struct file_system_type *fs_type,
1093         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1094 {
1095         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1096 }
1097
1098 #ifdef CONFIG_QUOTA
1099
1100 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1101  * acquiring the locks... As quota files are never truncated and quota code
1102  * itself serializes the operations (and noone else should touch the files)
1103  * we don't have to be afraid of races */
1104 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1105                                size_t len, loff_t off)
1106 {
1107         struct inode *inode = sb_dqopt(sb)->files[type];
1108         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1109         int err = 0;
1110         int offset = off & (sb->s_blocksize - 1);
1111         int tocopy;
1112         size_t toread;
1113         struct buffer_head tmp_bh;
1114         struct buffer_head *bh;
1115         loff_t i_size = i_size_read(inode);
1116
1117         if (off > i_size)
1118                 return 0;
1119         if (off+len > i_size)
1120                 len = i_size-off;
1121         toread = len;
1122         while (toread > 0) {
1123                 tocopy = sb->s_blocksize - offset < toread ?
1124                                 sb->s_blocksize - offset : toread;
1125
1126                 tmp_bh.b_state = 0;
1127                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1128                 if (err)
1129                         return err;
1130                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1131                         memset(data, 0, tocopy);
1132                 else {
1133                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1134                         if (!bh)
1135                                 return -EIO;
1136                         memcpy(data, bh->b_data+offset, tocopy);
1137                         brelse(bh);
1138                 }
1139                 offset = 0;
1140                 toread -= tocopy;
1141                 data += tocopy;
1142                 blk++;
1143         }
1144         return len;
1145 }
1146
1147 /* Write to quotafile */
1148 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1149                                 const char *data, size_t len, loff_t off)
1150 {
1151         struct inode *inode = sb_dqopt(sb)->files[type];
1152         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1153         int err = 0;
1154         int offset = off & (sb->s_blocksize - 1);
1155         int tocopy;
1156         size_t towrite = len;
1157         struct buffer_head tmp_bh;
1158         struct buffer_head *bh;
1159
1160         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1161         while (towrite > 0) {
1162                 tocopy = sb->s_blocksize - offset < towrite ?
1163                                 sb->s_blocksize - offset : towrite;
1164
1165                 tmp_bh.b_state = 0;
1166                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1167                 if (err)
1168                         goto out;
1169                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1170                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1171                 else
1172                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1173                 if (!bh) {
1174                         err = -EIO;
1175                         goto out;
1176                 }
1177                 lock_buffer(bh);
1178                 memcpy(bh->b_data+offset, data, tocopy);
1179                 flush_dcache_page(bh->b_page);
1180                 set_buffer_uptodate(bh);
1181                 mark_buffer_dirty(bh);
1182                 unlock_buffer(bh);
1183                 brelse(bh);
1184                 offset = 0;
1185                 towrite -= tocopy;
1186                 data += tocopy;
1187                 blk++;
1188         }
1189 out:
1190         if (len == towrite)
1191                 return err;
1192         if (inode->i_size < off+len-towrite)
1193                 i_size_write(inode, off+len-towrite);
1194         inode->i_version++;
1195         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1196         mark_inode_dirty(inode);
1197         mutex_unlock(&inode->i_mutex);
1198         return len - towrite;
1199 }
1200
1201 #endif
1202
1203 static struct file_system_type ext2_fs_type = {
1204         .owner          = THIS_MODULE,
1205         .name           = "ext2",
1206         .get_sb         = ext2_get_sb,
1207         .kill_sb        = kill_block_super,
1208         .fs_flags       = FS_REQUIRES_DEV,
1209 };
1210
1211 static int __init init_ext2_fs(void)
1212 {
1213         int err = init_ext2_xattr();
1214         if (err)
1215                 return err;
1216         err = init_inodecache();
1217         if (err)
1218                 goto out1;
1219         err = register_filesystem(&ext2_fs_type);
1220         if (err)
1221                 goto out;
1222         return 0;
1223 out:
1224         destroy_inodecache();
1225 out1:
1226         exit_ext2_xattr();
1227         return err;
1228 }
1229
1230 static void __exit exit_ext2_fs(void)
1231 {
1232         unregister_filesystem(&ext2_fs_type);
1233         destroy_inodecache();
1234         exit_ext2_xattr();
1235 }
1236
1237 module_init(init_ext2_fs)
1238 module_exit(exit_ext2_fs)