Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6
[linux-2.6] / 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/exportfs.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 <linux/log2.h>
34 #include <asm/uaccess.h>
35 #include "ext2.h"
36 #include "xattr.h"
37 #include "acl.h"
38 #include "xip.h"
39
40 static void ext2_sync_super(struct super_block *sb,
41                             struct ext2_super_block *es);
42 static int ext2_remount (struct super_block * sb, int * flags, char * data);
43 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
44
45 void ext2_error (struct super_block * sb, const char * function,
46                  const char * fmt, ...)
47 {
48         va_list args;
49         struct ext2_sb_info *sbi = EXT2_SB(sb);
50         struct ext2_super_block *es = sbi->s_es;
51
52         if (!(sb->s_flags & MS_RDONLY)) {
53                 sbi->s_mount_state |= EXT2_ERROR_FS;
54                 es->s_state =
55                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
56                 ext2_sync_super(sb, es);
57         }
58
59         va_start(args, fmt);
60         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
61         vprintk(fmt, args);
62         printk("\n");
63         va_end(args);
64
65         if (test_opt(sb, ERRORS_PANIC))
66                 panic("EXT2-fs panic from previous error\n");
67         if (test_opt(sb, ERRORS_RO)) {
68                 printk("Remounting filesystem read-only\n");
69                 sb->s_flags |= MS_RDONLY;
70         }
71 }
72
73 void ext2_warning (struct super_block * sb, const char * function,
74                    const char * fmt, ...)
75 {
76         va_list args;
77
78         va_start(args, fmt);
79         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
80                sb->s_id, function);
81         vprintk(fmt, args);
82         printk("\n");
83         va_end(args);
84 }
85
86 void ext2_update_dynamic_rev(struct super_block *sb)
87 {
88         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
89
90         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
91                 return;
92
93         ext2_warning(sb, __FUNCTION__,
94                      "updating to rev %d because of new feature flag, "
95                      "running e2fsck is recommended",
96                      EXT2_DYNAMIC_REV);
97
98         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
99         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
100         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
101         /* leave es->s_feature_*compat flags alone */
102         /* es->s_uuid will be set by e2fsck if empty */
103
104         /*
105          * The rest of the superblock fields should be zero, and if not it
106          * means they are likely already in use, so leave them alone.  We
107          * can leave it up to e2fsck to clean up any inconsistencies there.
108          */
109 }
110
111 static void ext2_put_super (struct super_block * sb)
112 {
113         int db_count;
114         int i;
115         struct ext2_sb_info *sbi = EXT2_SB(sb);
116
117         ext2_xattr_put_super(sb);
118         if (!(sb->s_flags & MS_RDONLY)) {
119                 struct ext2_super_block *es = sbi->s_es;
120
121                 es->s_state = cpu_to_le16(sbi->s_mount_state);
122                 ext2_sync_super(sb, es);
123         }
124         db_count = sbi->s_gdb_count;
125         for (i = 0; i < db_count; i++)
126                 if (sbi->s_group_desc[i])
127                         brelse (sbi->s_group_desc[i]);
128         kfree(sbi->s_group_desc);
129         kfree(sbi->s_debts);
130         percpu_counter_destroy(&sbi->s_freeblocks_counter);
131         percpu_counter_destroy(&sbi->s_freeinodes_counter);
132         percpu_counter_destroy(&sbi->s_dirs_counter);
133         brelse (sbi->s_sbh);
134         sb->s_fs_info = NULL;
135         kfree(sbi);
136
137         return;
138 }
139
140 static struct kmem_cache * ext2_inode_cachep;
141
142 static struct inode *ext2_alloc_inode(struct super_block *sb)
143 {
144         struct ext2_inode_info *ei;
145         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, GFP_KERNEL);
146         if (!ei)
147                 return NULL;
148 #ifdef CONFIG_EXT2_FS_POSIX_ACL
149         ei->i_acl = EXT2_ACL_NOT_CACHED;
150         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
151 #endif
152         ei->i_block_alloc_info = NULL;
153         ei->vfs_inode.i_version = 1;
154         return &ei->vfs_inode;
155 }
156
157 static void ext2_destroy_inode(struct inode *inode)
158 {
159         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
160 }
161
162 static void init_once(struct kmem_cache * cachep, void *foo)
163 {
164         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
165
166         rwlock_init(&ei->i_meta_lock);
167 #ifdef CONFIG_EXT2_FS_XATTR
168         init_rwsem(&ei->xattr_sem);
169 #endif
170         mutex_init(&ei->truncate_mutex);
171         inode_init_once(&ei->vfs_inode);
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);
181         if (ext2_inode_cachep == NULL)
182                 return -ENOMEM;
183         return 0;
184 }
185
186 static void destroy_inodecache(void)
187 {
188         kmem_cache_destroy(ext2_inode_cachep);
189 }
190
191 static void ext2_clear_inode(struct inode *inode)
192 {
193         struct ext2_block_alloc_info *rsv = EXT2_I(inode)->i_block_alloc_info;
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         ext2_discard_reservation(inode);
207         EXT2_I(inode)->i_block_alloc_info = NULL;
208         if (unlikely(rsv))
209                 kfree(rsv);
210 }
211
212 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
213 {
214         struct super_block *sb = vfs->mnt_sb;
215         struct ext2_sb_info *sbi = EXT2_SB(sb);
216         struct ext2_super_block *es = sbi->s_es;
217         unsigned long def_mount_opts;
218
219         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
220
221         if (sbi->s_sb_block != 1)
222                 seq_printf(seq, ",sb=%lu", sbi->s_sb_block);
223         if (test_opt(sb, MINIX_DF))
224                 seq_puts(seq, ",minixdf");
225         if (test_opt(sb, GRPID))
226                 seq_puts(seq, ",grpid");
227         if (!test_opt(sb, GRPID) && (def_mount_opts & EXT2_DEFM_BSDGROUPS))
228                 seq_puts(seq, ",nogrpid");
229         if (sbi->s_resuid != EXT2_DEF_RESUID ||
230             le16_to_cpu(es->s_def_resuid) != EXT2_DEF_RESUID) {
231                 seq_printf(seq, ",resuid=%u", sbi->s_resuid);
232         }
233         if (sbi->s_resgid != EXT2_DEF_RESGID ||
234             le16_to_cpu(es->s_def_resgid) != EXT2_DEF_RESGID) {
235                 seq_printf(seq, ",resgid=%u", sbi->s_resgid);
236         }
237         if (test_opt(sb, ERRORS_RO)) {
238                 int def_errors = le16_to_cpu(es->s_errors);
239
240                 if (def_errors == EXT2_ERRORS_PANIC ||
241                     def_errors == EXT2_ERRORS_CONTINUE) {
242                         seq_puts(seq, ",errors=remount-ro");
243                 }
244         }
245         if (test_opt(sb, ERRORS_CONT))
246                 seq_puts(seq, ",errors=continue");
247         if (test_opt(sb, ERRORS_PANIC))
248                 seq_puts(seq, ",errors=panic");
249         if (test_opt(sb, NO_UID32))
250                 seq_puts(seq, ",nouid32");
251         if (test_opt(sb, DEBUG))
252                 seq_puts(seq, ",debug");
253         if (test_opt(sb, OLDALLOC))
254                 seq_puts(seq, ",oldalloc");
255
256 #ifdef CONFIG_EXT2_FS_XATTR
257         if (test_opt(sb, XATTR_USER))
258                 seq_puts(seq, ",user_xattr");
259         if (!test_opt(sb, XATTR_USER) &&
260             (def_mount_opts & EXT2_DEFM_XATTR_USER)) {
261                 seq_puts(seq, ",nouser_xattr");
262         }
263 #endif
264
265 #ifdef CONFIG_EXT2_FS_POSIX_ACL
266         if (test_opt(sb, POSIX_ACL))
267                 seq_puts(seq, ",acl");
268         if (!test_opt(sb, POSIX_ACL) && (def_mount_opts & EXT2_DEFM_ACL))
269                 seq_puts(seq, ",noacl");
270 #endif
271
272         if (test_opt(sb, NOBH))
273                 seq_puts(seq, ",nobh");
274
275 #if defined(CONFIG_QUOTA)
276         if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
277                 seq_puts(seq, ",usrquota");
278
279         if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
280                 seq_puts(seq, ",grpquota");
281 #endif
282
283 #if defined(CONFIG_EXT2_FS_XIP)
284         if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
285                 seq_puts(seq, ",xip");
286 #endif
287
288         return 0;
289 }
290
291 #ifdef CONFIG_QUOTA
292 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
293 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
294 #endif
295
296 static const struct super_operations ext2_sops = {
297         .alloc_inode    = ext2_alloc_inode,
298         .destroy_inode  = ext2_destroy_inode,
299         .write_inode    = ext2_write_inode,
300         .delete_inode   = ext2_delete_inode,
301         .put_super      = ext2_put_super,
302         .write_super    = ext2_write_super,
303         .statfs         = ext2_statfs,
304         .remount_fs     = ext2_remount,
305         .clear_inode    = ext2_clear_inode,
306         .show_options   = ext2_show_options,
307 #ifdef CONFIG_QUOTA
308         .quota_read     = ext2_quota_read,
309         .quota_write    = ext2_quota_write,
310 #endif
311 };
312
313 static struct inode *ext2_nfs_get_inode(struct super_block *sb,
314                 u64 ino, u32 generation)
315 {
316         struct inode *inode;
317
318         if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
319                 return ERR_PTR(-ESTALE);
320         if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
321                 return ERR_PTR(-ESTALE);
322
323         /* iget isn't really right if the inode is currently unallocated!!
324          * ext2_read_inode currently does appropriate checks, but
325          * it might be "neater" to call ext2_get_inode first and check
326          * if the inode is valid.....
327          */
328         inode = ext2_iget(sb, ino);
329         if (IS_ERR(inode))
330                 return ERR_CAST(inode);
331         if (generation && inode->i_generation != generation) {
332                 /* we didn't find the right inode.. */
333                 iput(inode);
334                 return ERR_PTR(-ESTALE);
335         }
336         return inode;
337 }
338
339 static struct dentry *ext2_fh_to_dentry(struct super_block *sb, struct fid *fid,
340                 int fh_len, int fh_type)
341 {
342         return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
343                                     ext2_nfs_get_inode);
344 }
345
346 static struct dentry *ext2_fh_to_parent(struct super_block *sb, struct fid *fid,
347                 int fh_len, int fh_type)
348 {
349         return generic_fh_to_parent(sb, fid, fh_len, fh_type,
350                                     ext2_nfs_get_inode);
351 }
352
353 /* Yes, most of these are left as NULL!!
354  * A NULL value implies the default, which works with ext2-like file
355  * systems, but can be improved upon.
356  * Currently only get_parent is required.
357  */
358 static const struct export_operations ext2_export_ops = {
359         .fh_to_dentry = ext2_fh_to_dentry,
360         .fh_to_parent = ext2_fh_to_parent,
361         .get_parent = ext2_get_parent,
362 };
363
364 static unsigned long get_sb_block(void **data)
365 {
366         unsigned long   sb_block;
367         char            *options = (char *) *data;
368
369         if (!options || strncmp(options, "sb=", 3) != 0)
370                 return 1;       /* Default location */
371         options += 3;
372         sb_block = simple_strtoul(options, &options, 0);
373         if (*options && *options != ',') {
374                 printk("EXT2-fs: Invalid sb specification: %s\n",
375                        (char *) *data);
376                 return 1;
377         }
378         if (*options == ',')
379                 options++;
380         *data = (void *) options;
381         return sb_block;
382 }
383
384 enum {
385         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
386         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
387         Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
388         Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
389         Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
390         Opt_usrquota, Opt_grpquota, Opt_reservation, Opt_noreservation
391 };
392
393 static match_table_t tokens = {
394         {Opt_bsd_df, "bsddf"},
395         {Opt_minix_df, "minixdf"},
396         {Opt_grpid, "grpid"},
397         {Opt_grpid, "bsdgroups"},
398         {Opt_nogrpid, "nogrpid"},
399         {Opt_nogrpid, "sysvgroups"},
400         {Opt_resgid, "resgid=%u"},
401         {Opt_resuid, "resuid=%u"},
402         {Opt_sb, "sb=%u"},
403         {Opt_err_cont, "errors=continue"},
404         {Opt_err_panic, "errors=panic"},
405         {Opt_err_ro, "errors=remount-ro"},
406         {Opt_nouid32, "nouid32"},
407         {Opt_nocheck, "check=none"},
408         {Opt_nocheck, "nocheck"},
409         {Opt_debug, "debug"},
410         {Opt_oldalloc, "oldalloc"},
411         {Opt_orlov, "orlov"},
412         {Opt_nobh, "nobh"},
413         {Opt_user_xattr, "user_xattr"},
414         {Opt_nouser_xattr, "nouser_xattr"},
415         {Opt_acl, "acl"},
416         {Opt_noacl, "noacl"},
417         {Opt_xip, "xip"},
418         {Opt_grpquota, "grpquota"},
419         {Opt_ignore, "noquota"},
420         {Opt_quota, "quota"},
421         {Opt_usrquota, "usrquota"},
422         {Opt_reservation, "reservation"},
423         {Opt_noreservation, "noreservation"},
424         {Opt_err, NULL}
425 };
426
427 static int parse_options (char * options,
428                           struct ext2_sb_info *sbi)
429 {
430         char * p;
431         substring_t args[MAX_OPT_ARGS];
432         int option;
433
434         if (!options)
435                 return 1;
436
437         while ((p = strsep (&options, ",")) != NULL) {
438                 int token;
439                 if (!*p)
440                         continue;
441
442                 token = match_token(p, tokens, args);
443                 switch (token) {
444                 case Opt_bsd_df:
445                         clear_opt (sbi->s_mount_opt, MINIX_DF);
446                         break;
447                 case Opt_minix_df:
448                         set_opt (sbi->s_mount_opt, MINIX_DF);
449                         break;
450                 case Opt_grpid:
451                         set_opt (sbi->s_mount_opt, GRPID);
452                         break;
453                 case Opt_nogrpid:
454                         clear_opt (sbi->s_mount_opt, GRPID);
455                         break;
456                 case Opt_resuid:
457                         if (match_int(&args[0], &option))
458                                 return 0;
459                         sbi->s_resuid = option;
460                         break;
461                 case Opt_resgid:
462                         if (match_int(&args[0], &option))
463                                 return 0;
464                         sbi->s_resgid = option;
465                         break;
466                 case Opt_sb:
467                         /* handled by get_sb_block() instead of here */
468                         /* *sb_block = match_int(&args[0]); */
469                         break;
470                 case Opt_err_panic:
471                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
472                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
473                         set_opt (sbi->s_mount_opt, ERRORS_PANIC);
474                         break;
475                 case Opt_err_ro:
476                         clear_opt (sbi->s_mount_opt, ERRORS_CONT);
477                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
478                         set_opt (sbi->s_mount_opt, ERRORS_RO);
479                         break;
480                 case Opt_err_cont:
481                         clear_opt (sbi->s_mount_opt, ERRORS_RO);
482                         clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
483                         set_opt (sbi->s_mount_opt, ERRORS_CONT);
484                         break;
485                 case Opt_nouid32:
486                         set_opt (sbi->s_mount_opt, NO_UID32);
487                         break;
488                 case Opt_nocheck:
489                         clear_opt (sbi->s_mount_opt, CHECK);
490                         break;
491                 case Opt_debug:
492                         set_opt (sbi->s_mount_opt, DEBUG);
493                         break;
494                 case Opt_oldalloc:
495                         set_opt (sbi->s_mount_opt, OLDALLOC);
496                         break;
497                 case Opt_orlov:
498                         clear_opt (sbi->s_mount_opt, OLDALLOC);
499                         break;
500                 case Opt_nobh:
501                         set_opt (sbi->s_mount_opt, NOBH);
502                         break;
503 #ifdef CONFIG_EXT2_FS_XATTR
504                 case Opt_user_xattr:
505                         set_opt (sbi->s_mount_opt, XATTR_USER);
506                         break;
507                 case Opt_nouser_xattr:
508                         clear_opt (sbi->s_mount_opt, XATTR_USER);
509                         break;
510 #else
511                 case Opt_user_xattr:
512                 case Opt_nouser_xattr:
513                         printk("EXT2 (no)user_xattr options not supported\n");
514                         break;
515 #endif
516 #ifdef CONFIG_EXT2_FS_POSIX_ACL
517                 case Opt_acl:
518                         set_opt(sbi->s_mount_opt, POSIX_ACL);
519                         break;
520                 case Opt_noacl:
521                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
522                         break;
523 #else
524                 case Opt_acl:
525                 case Opt_noacl:
526                         printk("EXT2 (no)acl options not supported\n");
527                         break;
528 #endif
529                 case Opt_xip:
530 #ifdef CONFIG_EXT2_FS_XIP
531                         set_opt (sbi->s_mount_opt, XIP);
532 #else
533                         printk("EXT2 xip option not supported\n");
534 #endif
535                         break;
536
537 #if defined(CONFIG_QUOTA)
538                 case Opt_quota:
539                 case Opt_usrquota:
540                         set_opt(sbi->s_mount_opt, USRQUOTA);
541                         break;
542
543                 case Opt_grpquota:
544                         set_opt(sbi->s_mount_opt, GRPQUOTA);
545                         break;
546 #else
547                 case Opt_quota:
548                 case Opt_usrquota:
549                 case Opt_grpquota:
550                         printk(KERN_ERR
551                                 "EXT2-fs: quota operations not supported.\n");
552
553                         break;
554 #endif
555
556                 case Opt_reservation:
557                         set_opt(sbi->s_mount_opt, RESERVATION);
558                         printk("reservations ON\n");
559                         break;
560                 case Opt_noreservation:
561                         clear_opt(sbi->s_mount_opt, RESERVATION);
562                         printk("reservations OFF\n");
563                         break;
564                 case Opt_ignore:
565                         break;
566                 default:
567                         return 0;
568                 }
569         }
570         return 1;
571 }
572
573 static int ext2_setup_super (struct super_block * sb,
574                               struct ext2_super_block * es,
575                               int read_only)
576 {
577         int res = 0;
578         struct ext2_sb_info *sbi = EXT2_SB(sb);
579
580         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
581                 printk ("EXT2-fs warning: revision level too high, "
582                         "forcing read-only mode\n");
583                 res = MS_RDONLY;
584         }
585         if (read_only)
586                 return res;
587         if (!(sbi->s_mount_state & EXT2_VALID_FS))
588                 printk ("EXT2-fs warning: mounting unchecked fs, "
589                         "running e2fsck is recommended\n");
590         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
591                 printk ("EXT2-fs warning: mounting fs with errors, "
592                         "running e2fsck is recommended\n");
593         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
594                  le16_to_cpu(es->s_mnt_count) >=
595                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
596                 printk ("EXT2-fs warning: maximal mount count reached, "
597                         "running e2fsck is recommended\n");
598         else if (le32_to_cpu(es->s_checkinterval) &&
599                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
600                 printk ("EXT2-fs warning: checktime reached, "
601                         "running e2fsck is recommended\n");
602         if (!le16_to_cpu(es->s_max_mnt_count))
603                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
604         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
605         ext2_write_super(sb);
606         if (test_opt (sb, DEBUG))
607                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
608                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
609                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
610                         sbi->s_frag_size,
611                         sbi->s_groups_count,
612                         EXT2_BLOCKS_PER_GROUP(sb),
613                         EXT2_INODES_PER_GROUP(sb),
614                         sbi->s_mount_opt);
615         return res;
616 }
617
618 static int ext2_check_descriptors(struct super_block *sb)
619 {
620         int i;
621         struct ext2_sb_info *sbi = EXT2_SB(sb);
622         unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
623         unsigned long last_block;
624
625         ext2_debug ("Checking group descriptors");
626
627         for (i = 0; i < sbi->s_groups_count; i++) {
628                 struct ext2_group_desc *gdp = ext2_get_group_desc(sb, i, NULL);
629
630                 if (i == sbi->s_groups_count - 1)
631                         last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
632                 else
633                         last_block = first_block +
634                                 (EXT2_BLOCKS_PER_GROUP(sb) - 1);
635
636                 if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
637                     le32_to_cpu(gdp->bg_block_bitmap) > last_block)
638                 {
639                         ext2_error (sb, "ext2_check_descriptors",
640                                     "Block bitmap for group %d"
641                                     " not in group (block %lu)!",
642                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
643                         return 0;
644                 }
645                 if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
646                     le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
647                 {
648                         ext2_error (sb, "ext2_check_descriptors",
649                                     "Inode bitmap for group %d"
650                                     " not in group (block %lu)!",
651                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
652                         return 0;
653                 }
654                 if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
655                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group - 1 >
656                     last_block)
657                 {
658                         ext2_error (sb, "ext2_check_descriptors",
659                                     "Inode table for group %d"
660                                     " not in group (block %lu)!",
661                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
662                         return 0;
663                 }
664                 first_block += EXT2_BLOCKS_PER_GROUP(sb);
665         }
666         return 1;
667 }
668
669 /*
670  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
671  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
672  * We need to be 1 filesystem block less than the 2^32 sector limit.
673  */
674 static loff_t ext2_max_size(int bits)
675 {
676         loff_t res = EXT2_NDIR_BLOCKS;
677         int meta_blocks;
678         loff_t upper_limit;
679
680         /* This is calculated to be the largest file size for a
681          * dense, file such that the total number of
682          * sectors in the file, including data and all indirect blocks,
683          * does not exceed 2^32 -1
684          * __u32 i_blocks representing the total number of
685          * 512 bytes blocks of the file
686          */
687         upper_limit = (1LL << 32) - 1;
688
689         /* total blocks in file system block size */
690         upper_limit >>= (bits - 9);
691
692
693         /* indirect blocks */
694         meta_blocks = 1;
695         /* double indirect blocks */
696         meta_blocks += 1 + (1LL << (bits-2));
697         /* tripple indirect blocks */
698         meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2)));
699
700         upper_limit -= meta_blocks;
701         upper_limit <<= bits;
702
703         res += 1LL << (bits-2);
704         res += 1LL << (2*(bits-2));
705         res += 1LL << (3*(bits-2));
706         res <<= bits;
707         if (res > upper_limit)
708                 res = upper_limit;
709
710         if (res > MAX_LFS_FILESIZE)
711                 res = MAX_LFS_FILESIZE;
712
713         return res;
714 }
715
716 static unsigned long descriptor_loc(struct super_block *sb,
717                                     unsigned long logic_sb_block,
718                                     int nr)
719 {
720         struct ext2_sb_info *sbi = EXT2_SB(sb);
721         unsigned long bg, first_data_block, first_meta_bg;
722         int has_super = 0;
723         
724         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
725         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
726
727         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
728             nr < first_meta_bg)
729                 return (logic_sb_block + nr + 1);
730         bg = sbi->s_desc_per_block * nr;
731         if (ext2_bg_has_super(sb, bg))
732                 has_super = 1;
733         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
734 }
735
736 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
737 {
738         struct buffer_head * bh;
739         struct ext2_sb_info * sbi;
740         struct ext2_super_block * es;
741         struct inode *root;
742         unsigned long block;
743         unsigned long sb_block = get_sb_block(&data);
744         unsigned long logic_sb_block;
745         unsigned long offset = 0;
746         unsigned long def_mount_opts;
747         long ret = -EINVAL;
748         int blocksize = BLOCK_SIZE;
749         int db_count;
750         int i, j;
751         __le32 features;
752         int err;
753
754         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
755         if (!sbi)
756                 return -ENOMEM;
757         sb->s_fs_info = sbi;
758         sbi->s_sb_block = sb_block;
759
760         /*
761          * See what the current blocksize for the device is, and
762          * use that as the blocksize.  Otherwise (or if the blocksize
763          * is smaller than the default) use the default.
764          * This is important for devices that have a hardware
765          * sectorsize that is larger than the default.
766          */
767         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
768         if (!blocksize) {
769                 printk ("EXT2-fs: unable to set blocksize\n");
770                 goto failed_sbi;
771         }
772
773         /*
774          * If the superblock doesn't start on a hardware sector boundary,
775          * calculate the offset.  
776          */
777         if (blocksize != BLOCK_SIZE) {
778                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
779                 offset = (sb_block*BLOCK_SIZE) % blocksize;
780         } else {
781                 logic_sb_block = sb_block;
782         }
783
784         if (!(bh = sb_bread(sb, logic_sb_block))) {
785                 printk ("EXT2-fs: unable to read superblock\n");
786                 goto failed_sbi;
787         }
788         /*
789          * Note: s_es must be initialized as soon as possible because
790          *       some ext2 macro-instructions depend on its value
791          */
792         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
793         sbi->s_es = es;
794         sb->s_magic = le16_to_cpu(es->s_magic);
795
796         if (sb->s_magic != EXT2_SUPER_MAGIC)
797                 goto cantfind_ext2;
798
799         /* Set defaults before we parse the mount options */
800         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
801         if (def_mount_opts & EXT2_DEFM_DEBUG)
802                 set_opt(sbi->s_mount_opt, DEBUG);
803         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
804                 set_opt(sbi->s_mount_opt, GRPID);
805         if (def_mount_opts & EXT2_DEFM_UID16)
806                 set_opt(sbi->s_mount_opt, NO_UID32);
807 #ifdef CONFIG_EXT2_FS_XATTR
808         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
809                 set_opt(sbi->s_mount_opt, XATTR_USER);
810 #endif
811 #ifdef CONFIG_EXT2_FS_POSIX_ACL
812         if (def_mount_opts & EXT2_DEFM_ACL)
813                 set_opt(sbi->s_mount_opt, POSIX_ACL);
814 #endif
815         
816         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
817                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
818         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_CONTINUE)
819                 set_opt(sbi->s_mount_opt, ERRORS_CONT);
820         else
821                 set_opt(sbi->s_mount_opt, ERRORS_RO);
822
823         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
824         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
825         
826         set_opt(sbi->s_mount_opt, RESERVATION);
827
828         if (!parse_options ((char *) data, sbi))
829                 goto failed_mount;
830
831         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
832                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
833                  MS_POSIXACL : 0);
834
835         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
836                                     EXT2_MOUNT_XIP if not */
837
838         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
839             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
840              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
841              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
842                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
843                        "running e2fsck is recommended\n");
844         /*
845          * Check feature flags regardless of the revision level, since we
846          * previously didn't change the revision level when setting the flags,
847          * so there is a chance incompat flags are set on a rev 0 filesystem.
848          */
849         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
850         if (features) {
851                 printk("EXT2-fs: %s: couldn't mount because of "
852                        "unsupported optional features (%x).\n",
853                        sb->s_id, le32_to_cpu(features));
854                 goto failed_mount;
855         }
856         if (!(sb->s_flags & MS_RDONLY) &&
857             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
858                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
859                        "unsupported optional features (%x).\n",
860                        sb->s_id, le32_to_cpu(features));
861                 goto failed_mount;
862         }
863
864         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
865
866         if (ext2_use_xip(sb) && blocksize != PAGE_SIZE) {
867                 if (!silent)
868                         printk("XIP: Unsupported blocksize\n");
869                 goto failed_mount;
870         }
871
872         /* If the blocksize doesn't match, re-read the thing.. */
873         if (sb->s_blocksize != blocksize) {
874                 brelse(bh);
875
876                 if (!sb_set_blocksize(sb, blocksize)) {
877                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
878                         goto failed_sbi;
879                 }
880
881                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
882                 offset = (sb_block*BLOCK_SIZE) % blocksize;
883                 bh = sb_bread(sb, logic_sb_block);
884                 if(!bh) {
885                         printk("EXT2-fs: Couldn't read superblock on "
886                                "2nd try.\n");
887                         goto failed_sbi;
888                 }
889                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
890                 sbi->s_es = es;
891                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
892                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
893                         goto failed_mount;
894                 }
895         }
896
897         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
898
899         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
900                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
901                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
902         } else {
903                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
904                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
905                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
906                     !is_power_of_2(sbi->s_inode_size) ||
907                     (sbi->s_inode_size > blocksize)) {
908                         printk ("EXT2-fs: unsupported inode size: %d\n",
909                                 sbi->s_inode_size);
910                         goto failed_mount;
911                 }
912         }
913
914         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
915                                    le32_to_cpu(es->s_log_frag_size);
916         if (sbi->s_frag_size == 0)
917                 goto cantfind_ext2;
918         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
919
920         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
921         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
922         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
923
924         if (EXT2_INODE_SIZE(sb) == 0)
925                 goto cantfind_ext2;
926         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
927         if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
928                 goto cantfind_ext2;
929         sbi->s_itb_per_group = sbi->s_inodes_per_group /
930                                         sbi->s_inodes_per_block;
931         sbi->s_desc_per_block = sb->s_blocksize /
932                                         sizeof (struct ext2_group_desc);
933         sbi->s_sbh = bh;
934         sbi->s_mount_state = le16_to_cpu(es->s_state);
935         sbi->s_addr_per_block_bits =
936                 ilog2 (EXT2_ADDR_PER_BLOCK(sb));
937         sbi->s_desc_per_block_bits =
938                 ilog2 (EXT2_DESC_PER_BLOCK(sb));
939
940         if (sb->s_magic != EXT2_SUPER_MAGIC)
941                 goto cantfind_ext2;
942
943         if (sb->s_blocksize != bh->b_size) {
944                 if (!silent)
945                         printk ("VFS: Unsupported blocksize on dev "
946                                 "%s.\n", sb->s_id);
947                 goto failed_mount;
948         }
949
950         if (sb->s_blocksize != sbi->s_frag_size) {
951                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
952                         sbi->s_frag_size, sb->s_blocksize);
953                 goto failed_mount;
954         }
955
956         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
957                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
958                         sbi->s_blocks_per_group);
959                 goto failed_mount;
960         }
961         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
962                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
963                         sbi->s_frags_per_group);
964                 goto failed_mount;
965         }
966         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
967                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
968                         sbi->s_inodes_per_group);
969                 goto failed_mount;
970         }
971
972         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
973                 goto cantfind_ext2;
974         sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
975                                 le32_to_cpu(es->s_first_data_block) - 1)
976                                         / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
977         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
978                    EXT2_DESC_PER_BLOCK(sb);
979         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
980         if (sbi->s_group_desc == NULL) {
981                 printk ("EXT2-fs: not enough memory\n");
982                 goto failed_mount;
983         }
984         bgl_lock_init(&sbi->s_blockgroup_lock);
985         sbi->s_debts = kcalloc(sbi->s_groups_count, sizeof(*sbi->s_debts), GFP_KERNEL);
986         if (!sbi->s_debts) {
987                 printk ("EXT2-fs: not enough memory\n");
988                 goto failed_mount_group_desc;
989         }
990         for (i = 0; i < db_count; i++) {
991                 block = descriptor_loc(sb, logic_sb_block, i);
992                 sbi->s_group_desc[i] = sb_bread(sb, block);
993                 if (!sbi->s_group_desc[i]) {
994                         for (j = 0; j < i; j++)
995                                 brelse (sbi->s_group_desc[j]);
996                         printk ("EXT2-fs: unable to read group descriptors\n");
997                         goto failed_mount_group_desc;
998                 }
999         }
1000         if (!ext2_check_descriptors (sb)) {
1001                 printk ("EXT2-fs: group descriptors corrupted!\n");
1002                 goto failed_mount2;
1003         }
1004         sbi->s_gdb_count = db_count;
1005         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
1006         spin_lock_init(&sbi->s_next_gen_lock);
1007
1008         /* per fileystem reservation list head & lock */
1009         spin_lock_init(&sbi->s_rsv_window_lock);
1010         sbi->s_rsv_window_root = RB_ROOT;
1011         /*
1012          * Add a single, static dummy reservation to the start of the
1013          * reservation window list --- it gives us a placeholder for
1014          * append-at-start-of-list which makes the allocation logic
1015          * _much_ simpler.
1016          */
1017         sbi->s_rsv_window_head.rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
1018         sbi->s_rsv_window_head.rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
1019         sbi->s_rsv_window_head.rsv_alloc_hit = 0;
1020         sbi->s_rsv_window_head.rsv_goal_size = 0;
1021         ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);
1022
1023         err = percpu_counter_init(&sbi->s_freeblocks_counter,
1024                                 ext2_count_free_blocks(sb));
1025         if (!err) {
1026                 err = percpu_counter_init(&sbi->s_freeinodes_counter,
1027                                 ext2_count_free_inodes(sb));
1028         }
1029         if (!err) {
1030                 err = percpu_counter_init(&sbi->s_dirs_counter,
1031                                 ext2_count_dirs(sb));
1032         }
1033         if (err) {
1034                 printk(KERN_ERR "EXT2-fs: insufficient memory\n");
1035                 goto failed_mount3;
1036         }
1037         /*
1038          * set up enough so that it can read an inode
1039          */
1040         sb->s_op = &ext2_sops;
1041         sb->s_export_op = &ext2_export_ops;
1042         sb->s_xattr = ext2_xattr_handlers;
1043         root = ext2_iget(sb, EXT2_ROOT_INO);
1044         if (IS_ERR(root)) {
1045                 ret = PTR_ERR(root);
1046                 goto failed_mount3;
1047         }
1048         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
1049                 iput(root);
1050                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
1051                 goto failed_mount3;
1052         }
1053
1054         sb->s_root = d_alloc_root(root);
1055         if (!sb->s_root) {
1056                 iput(root);
1057                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
1058                 ret = -ENOMEM;
1059                 goto failed_mount3;
1060         }
1061         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
1062                 ext2_warning(sb, __FUNCTION__,
1063                         "mounting ext3 filesystem as ext2");
1064         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
1065         return 0;
1066
1067 cantfind_ext2:
1068         if (!silent)
1069                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
1070                        sb->s_id);
1071         goto failed_mount;
1072 failed_mount3:
1073         percpu_counter_destroy(&sbi->s_freeblocks_counter);
1074         percpu_counter_destroy(&sbi->s_freeinodes_counter);
1075         percpu_counter_destroy(&sbi->s_dirs_counter);
1076 failed_mount2:
1077         for (i = 0; i < db_count; i++)
1078                 brelse(sbi->s_group_desc[i]);
1079 failed_mount_group_desc:
1080         kfree(sbi->s_group_desc);
1081         kfree(sbi->s_debts);
1082 failed_mount:
1083         brelse(bh);
1084 failed_sbi:
1085         sb->s_fs_info = NULL;
1086         kfree(sbi);
1087         return ret;
1088 }
1089
1090 static void ext2_commit_super (struct super_block * sb,
1091                                struct ext2_super_block * es)
1092 {
1093         es->s_wtime = cpu_to_le32(get_seconds());
1094         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
1095         sb->s_dirt = 0;
1096 }
1097
1098 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
1099 {
1100         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1101         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1102         es->s_wtime = cpu_to_le32(get_seconds());
1103         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
1104         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
1105         sb->s_dirt = 0;
1106 }
1107
1108 /*
1109  * In the second extended file system, it is not necessary to
1110  * write the super block since we use a mapping of the
1111  * disk super block in a buffer.
1112  *
1113  * However, this function is still used to set the fs valid
1114  * flags to 0.  We need to set this flag to 0 since the fs
1115  * may have been checked while mounted and e2fsck may have
1116  * set s_state to EXT2_VALID_FS after some corrections.
1117  */
1118
1119 void ext2_write_super (struct super_block * sb)
1120 {
1121         struct ext2_super_block * es;
1122         lock_kernel();
1123         if (!(sb->s_flags & MS_RDONLY)) {
1124                 es = EXT2_SB(sb)->s_es;
1125
1126                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1127                         ext2_debug ("setting valid to 0\n");
1128                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1129                                                   ~EXT2_VALID_FS);
1130                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1131                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1132                         es->s_mtime = cpu_to_le32(get_seconds());
1133                         ext2_sync_super(sb, es);
1134                 } else
1135                         ext2_commit_super (sb, es);
1136         }
1137         sb->s_dirt = 0;
1138         unlock_kernel();
1139 }
1140
1141 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1142 {
1143         struct ext2_sb_info * sbi = EXT2_SB(sb);
1144         struct ext2_super_block * es;
1145         unsigned long old_mount_opt = sbi->s_mount_opt;
1146         struct ext2_mount_options old_opts;
1147         unsigned long old_sb_flags;
1148         int err;
1149
1150         /* Store the old options */
1151         old_sb_flags = sb->s_flags;
1152         old_opts.s_mount_opt = sbi->s_mount_opt;
1153         old_opts.s_resuid = sbi->s_resuid;
1154         old_opts.s_resgid = sbi->s_resgid;
1155
1156         /*
1157          * Allow the "check" option to be passed as a remount option.
1158          */
1159         if (!parse_options (data, sbi)) {
1160                 err = -EINVAL;
1161                 goto restore_opts;
1162         }
1163
1164         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1165                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1166
1167         ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
1168                                     EXT2_MOUNT_XIP if not */
1169
1170         if ((ext2_use_xip(sb)) && (sb->s_blocksize != PAGE_SIZE)) {
1171                 printk("XIP: Unsupported blocksize\n");
1172                 err = -EINVAL;
1173                 goto restore_opts;
1174         }
1175
1176         es = sbi->s_es;
1177         if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1178             (old_mount_opt & EXT2_MOUNT_XIP)) &&
1179             invalidate_inodes(sb))
1180                 ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1181                              "xip remain in cache (no functional problem)");
1182         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1183                 return 0;
1184         if (*flags & MS_RDONLY) {
1185                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1186                     !(sbi->s_mount_state & EXT2_VALID_FS))
1187                         return 0;
1188                 /*
1189                  * OK, we are remounting a valid rw partition rdonly, so set
1190                  * the rdonly flag and then mark the partition as valid again.
1191                  */
1192                 es->s_state = cpu_to_le16(sbi->s_mount_state);
1193                 es->s_mtime = cpu_to_le32(get_seconds());
1194         } else {
1195                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1196                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
1197                 if (ret) {
1198                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
1199                                "unsupported optional features (%x).\n",
1200                                sb->s_id, le32_to_cpu(ret));
1201                         err = -EROFS;
1202                         goto restore_opts;
1203                 }
1204                 /*
1205                  * Mounting a RDONLY partition read-write, so reread and
1206                  * store the current valid flag.  (It may have been changed
1207                  * by e2fsck since we originally mounted the partition.)
1208                  */
1209                 sbi->s_mount_state = le16_to_cpu(es->s_state);
1210                 if (!ext2_setup_super (sb, es, 0))
1211                         sb->s_flags &= ~MS_RDONLY;
1212         }
1213         ext2_sync_super(sb, es);
1214         return 0;
1215 restore_opts:
1216         sbi->s_mount_opt = old_opts.s_mount_opt;
1217         sbi->s_resuid = old_opts.s_resuid;
1218         sbi->s_resgid = old_opts.s_resgid;
1219         sb->s_flags = old_sb_flags;
1220         return err;
1221 }
1222
1223 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1224 {
1225         struct super_block *sb = dentry->d_sb;
1226         struct ext2_sb_info *sbi = EXT2_SB(sb);
1227         struct ext2_super_block *es = sbi->s_es;
1228         u64 fsid;
1229
1230         if (test_opt (sb, MINIX_DF))
1231                 sbi->s_overhead_last = 0;
1232         else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) {
1233                 unsigned long i, overhead = 0;
1234                 smp_rmb();
1235
1236                 /*
1237                  * Compute the overhead (FS structures). This is constant
1238                  * for a given filesystem unless the number of block groups
1239                  * changes so we cache the previous value until it does.
1240                  */
1241
1242                 /*
1243                  * All of the blocks before first_data_block are
1244                  * overhead
1245                  */
1246                 overhead = le32_to_cpu(es->s_first_data_block);
1247
1248                 /*
1249                  * Add the overhead attributed to the superblock and
1250                  * block group descriptors.  If the sparse superblocks
1251                  * feature is turned on, then not all groups have this.
1252                  */
1253                 for (i = 0; i < sbi->s_groups_count; i++)
1254                         overhead += ext2_bg_has_super(sb, i) +
1255                                 ext2_bg_num_gdb(sb, i);
1256
1257                 /*
1258                  * Every block group has an inode bitmap, a block
1259                  * bitmap, and an inode table.
1260                  */
1261                 overhead += (sbi->s_groups_count *
1262                              (2 + sbi->s_itb_per_group));
1263                 sbi->s_overhead_last = overhead;
1264                 smp_wmb();
1265                 sbi->s_blocks_last = le32_to_cpu(es->s_blocks_count);
1266         }
1267
1268         buf->f_type = EXT2_SUPER_MAGIC;
1269         buf->f_bsize = sb->s_blocksize;
1270         buf->f_blocks = le32_to_cpu(es->s_blocks_count) - sbi->s_overhead_last;
1271         buf->f_bfree = ext2_count_free_blocks(sb);
1272         es->s_free_blocks_count = cpu_to_le32(buf->f_bfree);
1273         buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
1274         if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
1275                 buf->f_bavail = 0;
1276         buf->f_files = le32_to_cpu(es->s_inodes_count);
1277         buf->f_ffree = ext2_count_free_inodes(sb);
1278         es->s_free_inodes_count = cpu_to_le32(buf->f_ffree);
1279         buf->f_namelen = EXT2_NAME_LEN;
1280         fsid = le64_to_cpup((void *)es->s_uuid) ^
1281                le64_to_cpup((void *)es->s_uuid + sizeof(u64));
1282         buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
1283         buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
1284         return 0;
1285 }
1286
1287 static int ext2_get_sb(struct file_system_type *fs_type,
1288         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1289 {
1290         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1291 }
1292
1293 #ifdef CONFIG_QUOTA
1294
1295 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1296  * acquiring the locks... As quota files are never truncated and quota code
1297  * itself serializes the operations (and noone else should touch the files)
1298  * we don't have to be afraid of races */
1299 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1300                                size_t len, loff_t off)
1301 {
1302         struct inode *inode = sb_dqopt(sb)->files[type];
1303         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1304         int err = 0;
1305         int offset = off & (sb->s_blocksize - 1);
1306         int tocopy;
1307         size_t toread;
1308         struct buffer_head tmp_bh;
1309         struct buffer_head *bh;
1310         loff_t i_size = i_size_read(inode);
1311
1312         if (off > i_size)
1313                 return 0;
1314         if (off+len > i_size)
1315                 len = i_size-off;
1316         toread = len;
1317         while (toread > 0) {
1318                 tocopy = sb->s_blocksize - offset < toread ?
1319                                 sb->s_blocksize - offset : toread;
1320
1321                 tmp_bh.b_state = 0;
1322                 err = ext2_get_block(inode, blk, &tmp_bh, 0);
1323                 if (err < 0)
1324                         return err;
1325                 if (!buffer_mapped(&tmp_bh))    /* A hole? */
1326                         memset(data, 0, tocopy);
1327                 else {
1328                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1329                         if (!bh)
1330                                 return -EIO;
1331                         memcpy(data, bh->b_data+offset, tocopy);
1332                         brelse(bh);
1333                 }
1334                 offset = 0;
1335                 toread -= tocopy;
1336                 data += tocopy;
1337                 blk++;
1338         }
1339         return len;
1340 }
1341
1342 /* Write to quotafile */
1343 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1344                                 const char *data, size_t len, loff_t off)
1345 {
1346         struct inode *inode = sb_dqopt(sb)->files[type];
1347         sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1348         int err = 0;
1349         int offset = off & (sb->s_blocksize - 1);
1350         int tocopy;
1351         size_t towrite = len;
1352         struct buffer_head tmp_bh;
1353         struct buffer_head *bh;
1354
1355         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1356         while (towrite > 0) {
1357                 tocopy = sb->s_blocksize - offset < towrite ?
1358                                 sb->s_blocksize - offset : towrite;
1359
1360                 tmp_bh.b_state = 0;
1361                 err = ext2_get_block(inode, blk, &tmp_bh, 1);
1362                 if (err < 0)
1363                         goto out;
1364                 if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1365                         bh = sb_bread(sb, tmp_bh.b_blocknr);
1366                 else
1367                         bh = sb_getblk(sb, tmp_bh.b_blocknr);
1368                 if (!bh) {
1369                         err = -EIO;
1370                         goto out;
1371                 }
1372                 lock_buffer(bh);
1373                 memcpy(bh->b_data+offset, data, tocopy);
1374                 flush_dcache_page(bh->b_page);
1375                 set_buffer_uptodate(bh);
1376                 mark_buffer_dirty(bh);
1377                 unlock_buffer(bh);
1378                 brelse(bh);
1379                 offset = 0;
1380                 towrite -= tocopy;
1381                 data += tocopy;
1382                 blk++;
1383         }
1384 out:
1385         if (len == towrite)
1386                 return err;
1387         if (inode->i_size < off+len-towrite)
1388                 i_size_write(inode, off+len-towrite);
1389         inode->i_version++;
1390         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1391         mark_inode_dirty(inode);
1392         mutex_unlock(&inode->i_mutex);
1393         return len - towrite;
1394 }
1395
1396 #endif
1397
1398 static struct file_system_type ext2_fs_type = {
1399         .owner          = THIS_MODULE,
1400         .name           = "ext2",
1401         .get_sb         = ext2_get_sb,
1402         .kill_sb        = kill_block_super,
1403         .fs_flags       = FS_REQUIRES_DEV,
1404 };
1405
1406 static int __init init_ext2_fs(void)
1407 {
1408         int err = init_ext2_xattr();
1409         if (err)
1410                 return err;
1411         err = init_inodecache();
1412         if (err)
1413                 goto out1;
1414         err = register_filesystem(&ext2_fs_type);
1415         if (err)
1416                 goto out;
1417         return 0;
1418 out:
1419         destroy_inodecache();
1420 out1:
1421         exit_ext2_xattr();
1422         return err;
1423 }
1424
1425 static void __exit exit_ext2_fs(void)
1426 {
1427         unregister_filesystem(&ext2_fs_type);
1428         destroy_inodecache();
1429         exit_ext2_xattr();
1430 }
1431
1432 module_init(init_ext2_fs)
1433 module_exit(exit_ext2_fs)