xref: /openbmc/linux/fs/ext2/super.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 struct kmem_cache * 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, GFP_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, struct kmem_cache * cachep, unsigned long flags)
160 {
161 	struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
162 
163 	if (flags & SLAB_CTOR_CONSTRUCTOR) {
164 		rwlock_init(&ei->i_meta_lock);
165 #ifdef CONFIG_EXT2_FS_XATTR
166 		init_rwsem(&ei->xattr_sem);
167 #endif
168 		inode_init_once(&ei->vfs_inode);
169 	}
170 }
171 
172 static int init_inodecache(void)
173 {
174 	ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
175 					     sizeof(struct ext2_inode_info),
176 					     0, (SLAB_RECLAIM_ACCOUNT|
177 						SLAB_MEM_SPREAD),
178 					     init_once, NULL);
179 	if (ext2_inode_cachep == NULL)
180 		return -ENOMEM;
181 	return 0;
182 }
183 
184 static void destroy_inodecache(void)
185 {
186 	kmem_cache_destroy(ext2_inode_cachep);
187 }
188 
189 static void ext2_clear_inode(struct inode *inode)
190 {
191 #ifdef CONFIG_EXT2_FS_POSIX_ACL
192 	struct ext2_inode_info *ei = EXT2_I(inode);
193 
194 	if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
195 		posix_acl_release(ei->i_acl);
196 		ei->i_acl = EXT2_ACL_NOT_CACHED;
197 	}
198 	if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
199 		posix_acl_release(ei->i_default_acl);
200 		ei->i_default_acl = EXT2_ACL_NOT_CACHED;
201 	}
202 #endif
203 }
204 
205 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
206 {
207 	struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
208 
209 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
210 		seq_puts(seq, ",grpid");
211 
212 #if defined(CONFIG_QUOTA)
213 	if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
214 		seq_puts(seq, ",usrquota");
215 
216 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
217 		seq_puts(seq, ",grpquota");
218 #endif
219 
220 #if defined(CONFIG_EXT2_FS_XIP)
221 	if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
222 		seq_puts(seq, ",xip");
223 #endif
224 
225 	return 0;
226 }
227 
228 #ifdef CONFIG_QUOTA
229 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
230 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
231 #endif
232 
233 static const struct super_operations ext2_sops = {
234 	.alloc_inode	= ext2_alloc_inode,
235 	.destroy_inode	= ext2_destroy_inode,
236 	.read_inode	= ext2_read_inode,
237 	.write_inode	= ext2_write_inode,
238 	.put_inode	= ext2_put_inode,
239 	.delete_inode	= ext2_delete_inode,
240 	.put_super	= ext2_put_super,
241 	.write_super	= ext2_write_super,
242 	.statfs		= ext2_statfs,
243 	.remount_fs	= ext2_remount,
244 	.clear_inode	= ext2_clear_inode,
245 	.show_options	= ext2_show_options,
246 #ifdef CONFIG_QUOTA
247 	.quota_read	= ext2_quota_read,
248 	.quota_write	= ext2_quota_write,
249 #endif
250 };
251 
252 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
253 {
254 	__u32 *objp = vobjp;
255 	unsigned long ino = objp[0];
256 	__u32 generation = objp[1];
257 	struct inode *inode;
258 	struct dentry *result;
259 
260 	if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
261 		return ERR_PTR(-ESTALE);
262 	if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
263 		return ERR_PTR(-ESTALE);
264 
265 	/* iget isn't really right if the inode is currently unallocated!!
266 	 * ext2_read_inode currently does appropriate checks, but
267 	 * it might be "neater" to call ext2_get_inode first and check
268 	 * if the inode is valid.....
269 	 */
270 	inode = iget(sb, ino);
271 	if (inode == NULL)
272 		return ERR_PTR(-ENOMEM);
273 	if (is_bad_inode(inode) ||
274 	    (generation && inode->i_generation != generation)) {
275 		/* we didn't find the right inode.. */
276 		iput(inode);
277 		return ERR_PTR(-ESTALE);
278 	}
279 	/* now to find a dentry.
280 	 * If possible, get a well-connected one
281 	 */
282 	result = d_alloc_anon(inode);
283 	if (!result) {
284 		iput(inode);
285 		return ERR_PTR(-ENOMEM);
286 	}
287 	return result;
288 }
289 
290 /* Yes, most of these are left as NULL!!
291  * A NULL value implies the default, which works with ext2-like file
292  * systems, but can be improved upon.
293  * Currently only get_parent is required.
294  */
295 static struct export_operations ext2_export_ops = {
296 	.get_parent = ext2_get_parent,
297 	.get_dentry = ext2_get_dentry,
298 };
299 
300 static unsigned long get_sb_block(void **data)
301 {
302 	unsigned long 	sb_block;
303 	char 		*options = (char *) *data;
304 
305 	if (!options || strncmp(options, "sb=", 3) != 0)
306 		return 1;	/* Default location */
307 	options += 3;
308 	sb_block = simple_strtoul(options, &options, 0);
309 	if (*options && *options != ',') {
310 		printk("EXT2-fs: Invalid sb specification: %s\n",
311 		       (char *) *data);
312 		return 1;
313 	}
314 	if (*options == ',')
315 		options++;
316 	*data = (void *) options;
317 	return sb_block;
318 }
319 
320 enum {
321 	Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
322 	Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
323 	Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
324 	Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
325 	Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
326 	Opt_usrquota, Opt_grpquota
327 };
328 
329 static match_table_t tokens = {
330 	{Opt_bsd_df, "bsddf"},
331 	{Opt_minix_df, "minixdf"},
332 	{Opt_grpid, "grpid"},
333 	{Opt_grpid, "bsdgroups"},
334 	{Opt_nogrpid, "nogrpid"},
335 	{Opt_nogrpid, "sysvgroups"},
336 	{Opt_resgid, "resgid=%u"},
337 	{Opt_resuid, "resuid=%u"},
338 	{Opt_sb, "sb=%u"},
339 	{Opt_err_cont, "errors=continue"},
340 	{Opt_err_panic, "errors=panic"},
341 	{Opt_err_ro, "errors=remount-ro"},
342 	{Opt_nouid32, "nouid32"},
343 	{Opt_nocheck, "check=none"},
344 	{Opt_nocheck, "nocheck"},
345 	{Opt_debug, "debug"},
346 	{Opt_oldalloc, "oldalloc"},
347 	{Opt_orlov, "orlov"},
348 	{Opt_nobh, "nobh"},
349 	{Opt_user_xattr, "user_xattr"},
350 	{Opt_nouser_xattr, "nouser_xattr"},
351 	{Opt_acl, "acl"},
352 	{Opt_noacl, "noacl"},
353 	{Opt_xip, "xip"},
354 	{Opt_grpquota, "grpquota"},
355 	{Opt_ignore, "noquota"},
356 	{Opt_quota, "quota"},
357 	{Opt_usrquota, "usrquota"},
358 	{Opt_err, NULL}
359 };
360 
361 static int parse_options (char * options,
362 			  struct ext2_sb_info *sbi)
363 {
364 	char * p;
365 	substring_t args[MAX_OPT_ARGS];
366 	int option;
367 
368 	if (!options)
369 		return 1;
370 
371 	while ((p = strsep (&options, ",")) != NULL) {
372 		int token;
373 		if (!*p)
374 			continue;
375 
376 		token = match_token(p, tokens, args);
377 		switch (token) {
378 		case Opt_bsd_df:
379 			clear_opt (sbi->s_mount_opt, MINIX_DF);
380 			break;
381 		case Opt_minix_df:
382 			set_opt (sbi->s_mount_opt, MINIX_DF);
383 			break;
384 		case Opt_grpid:
385 			set_opt (sbi->s_mount_opt, GRPID);
386 			break;
387 		case Opt_nogrpid:
388 			clear_opt (sbi->s_mount_opt, GRPID);
389 			break;
390 		case Opt_resuid:
391 			if (match_int(&args[0], &option))
392 				return 0;
393 			sbi->s_resuid = option;
394 			break;
395 		case Opt_resgid:
396 			if (match_int(&args[0], &option))
397 				return 0;
398 			sbi->s_resgid = option;
399 			break;
400 		case Opt_sb:
401 			/* handled by get_sb_block() instead of here */
402 			/* *sb_block = match_int(&args[0]); */
403 			break;
404 		case Opt_err_panic:
405 			clear_opt (sbi->s_mount_opt, ERRORS_CONT);
406 			clear_opt (sbi->s_mount_opt, ERRORS_RO);
407 			set_opt (sbi->s_mount_opt, ERRORS_PANIC);
408 			break;
409 		case Opt_err_ro:
410 			clear_opt (sbi->s_mount_opt, ERRORS_CONT);
411 			clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
412 			set_opt (sbi->s_mount_opt, ERRORS_RO);
413 			break;
414 		case Opt_err_cont:
415 			clear_opt (sbi->s_mount_opt, ERRORS_RO);
416 			clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
417 			set_opt (sbi->s_mount_opt, ERRORS_CONT);
418 			break;
419 		case Opt_nouid32:
420 			set_opt (sbi->s_mount_opt, NO_UID32);
421 			break;
422 		case Opt_nocheck:
423 			clear_opt (sbi->s_mount_opt, CHECK);
424 			break;
425 		case Opt_debug:
426 			set_opt (sbi->s_mount_opt, DEBUG);
427 			break;
428 		case Opt_oldalloc:
429 			set_opt (sbi->s_mount_opt, OLDALLOC);
430 			break;
431 		case Opt_orlov:
432 			clear_opt (sbi->s_mount_opt, OLDALLOC);
433 			break;
434 		case Opt_nobh:
435 			set_opt (sbi->s_mount_opt, NOBH);
436 			break;
437 #ifdef CONFIG_EXT2_FS_XATTR
438 		case Opt_user_xattr:
439 			set_opt (sbi->s_mount_opt, XATTR_USER);
440 			break;
441 		case Opt_nouser_xattr:
442 			clear_opt (sbi->s_mount_opt, XATTR_USER);
443 			break;
444 #else
445 		case Opt_user_xattr:
446 		case Opt_nouser_xattr:
447 			printk("EXT2 (no)user_xattr options not supported\n");
448 			break;
449 #endif
450 #ifdef CONFIG_EXT2_FS_POSIX_ACL
451 		case Opt_acl:
452 			set_opt(sbi->s_mount_opt, POSIX_ACL);
453 			break;
454 		case Opt_noacl:
455 			clear_opt(sbi->s_mount_opt, POSIX_ACL);
456 			break;
457 #else
458 		case Opt_acl:
459 		case Opt_noacl:
460 			printk("EXT2 (no)acl options not supported\n");
461 			break;
462 #endif
463 		case Opt_xip:
464 #ifdef CONFIG_EXT2_FS_XIP
465 			set_opt (sbi->s_mount_opt, XIP);
466 #else
467 			printk("EXT2 xip option not supported\n");
468 #endif
469 			break;
470 
471 #if defined(CONFIG_QUOTA)
472 		case Opt_quota:
473 		case Opt_usrquota:
474 			set_opt(sbi->s_mount_opt, USRQUOTA);
475 			break;
476 
477 		case Opt_grpquota:
478 			set_opt(sbi->s_mount_opt, GRPQUOTA);
479 			break;
480 #else
481 		case Opt_quota:
482 		case Opt_usrquota:
483 		case Opt_grpquota:
484 			printk(KERN_ERR
485 				"EXT2-fs: quota operations not supported.\n");
486 
487 			break;
488 #endif
489 
490 		case Opt_ignore:
491 			break;
492 		default:
493 			return 0;
494 		}
495 	}
496 	return 1;
497 }
498 
499 static int ext2_setup_super (struct super_block * sb,
500 			      struct ext2_super_block * es,
501 			      int read_only)
502 {
503 	int res = 0;
504 	struct ext2_sb_info *sbi = EXT2_SB(sb);
505 
506 	if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
507 		printk ("EXT2-fs warning: revision level too high, "
508 			"forcing read-only mode\n");
509 		res = MS_RDONLY;
510 	}
511 	if (read_only)
512 		return res;
513 	if (!(sbi->s_mount_state & EXT2_VALID_FS))
514 		printk ("EXT2-fs warning: mounting unchecked fs, "
515 			"running e2fsck is recommended\n");
516 	else if ((sbi->s_mount_state & EXT2_ERROR_FS))
517 		printk ("EXT2-fs warning: mounting fs with errors, "
518 			"running e2fsck is recommended\n");
519 	else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
520 		 le16_to_cpu(es->s_mnt_count) >=
521 		 (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
522 		printk ("EXT2-fs warning: maximal mount count reached, "
523 			"running e2fsck is recommended\n");
524 	else if (le32_to_cpu(es->s_checkinterval) &&
525 		(le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
526 		printk ("EXT2-fs warning: checktime reached, "
527 			"running e2fsck is recommended\n");
528 	if (!le16_to_cpu(es->s_max_mnt_count))
529 		es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
530 	es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
531 	ext2_write_super(sb);
532 	if (test_opt (sb, DEBUG))
533 		printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
534 			"bpg=%lu, ipg=%lu, mo=%04lx]\n",
535 			EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
536 			sbi->s_frag_size,
537 			sbi->s_groups_count,
538 			EXT2_BLOCKS_PER_GROUP(sb),
539 			EXT2_INODES_PER_GROUP(sb),
540 			sbi->s_mount_opt);
541 	return res;
542 }
543 
544 static int ext2_check_descriptors (struct super_block * sb)
545 {
546 	int i;
547 	int desc_block = 0;
548 	struct ext2_sb_info *sbi = EXT2_SB(sb);
549 	unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
550 	unsigned long last_block;
551 	struct ext2_group_desc * gdp = NULL;
552 
553 	ext2_debug ("Checking group descriptors");
554 
555 	for (i = 0; i < sbi->s_groups_count; i++)
556 	{
557 		if (i == sbi->s_groups_count - 1)
558 			last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
559 		else
560 			last_block = first_block +
561 				(EXT2_BLOCKS_PER_GROUP(sb) - 1);
562 
563 		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
564 			gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
565 		if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
566 		    le32_to_cpu(gdp->bg_block_bitmap) > last_block)
567 		{
568 			ext2_error (sb, "ext2_check_descriptors",
569 				    "Block bitmap for group %d"
570 				    " not in group (block %lu)!",
571 				    i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
572 			return 0;
573 		}
574 		if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
575 		    le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
576 		{
577 			ext2_error (sb, "ext2_check_descriptors",
578 				    "Inode bitmap for group %d"
579 				    " not in group (block %lu)!",
580 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
581 			return 0;
582 		}
583 		if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
584 		    le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
585 		    last_block)
586 		{
587 			ext2_error (sb, "ext2_check_descriptors",
588 				    "Inode table for group %d"
589 				    " not in group (block %lu)!",
590 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
591 			return 0;
592 		}
593 		first_block += EXT2_BLOCKS_PER_GROUP(sb);
594 		gdp++;
595 	}
596 	return 1;
597 }
598 
599 /*
600  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
601  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
602  * We need to be 1 filesystem block less than the 2^32 sector limit.
603  */
604 static loff_t ext2_max_size(int bits)
605 {
606 	loff_t res = EXT2_NDIR_BLOCKS;
607 	/* This constant is calculated to be the largest file size for a
608 	 * dense, 4k-blocksize file such that the total number of
609 	 * sectors in the file, including data and all indirect blocks,
610 	 * does not exceed 2^32. */
611 	const loff_t upper_limit = 0x1ff7fffd000LL;
612 
613 	res += 1LL << (bits-2);
614 	res += 1LL << (2*(bits-2));
615 	res += 1LL << (3*(bits-2));
616 	res <<= bits;
617 	if (res > upper_limit)
618 		res = upper_limit;
619 	return res;
620 }
621 
622 static unsigned long descriptor_loc(struct super_block *sb,
623 				    unsigned long logic_sb_block,
624 				    int nr)
625 {
626 	struct ext2_sb_info *sbi = EXT2_SB(sb);
627 	unsigned long bg, first_data_block, first_meta_bg;
628 	int has_super = 0;
629 
630 	first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
631 	first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
632 
633 	if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
634 	    nr < first_meta_bg)
635 		return (logic_sb_block + nr + 1);
636 	bg = sbi->s_desc_per_block * nr;
637 	if (ext2_bg_has_super(sb, bg))
638 		has_super = 1;
639 	return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
640 }
641 
642 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
643 {
644 	struct buffer_head * bh;
645 	struct ext2_sb_info * sbi;
646 	struct ext2_super_block * es;
647 	struct inode *root;
648 	unsigned long block;
649 	unsigned long sb_block = get_sb_block(&data);
650 	unsigned long logic_sb_block;
651 	unsigned long offset = 0;
652 	unsigned long def_mount_opts;
653 	int blocksize = BLOCK_SIZE;
654 	int db_count;
655 	int i, j;
656 	__le32 features;
657 
658 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
659 	if (!sbi)
660 		return -ENOMEM;
661 	sb->s_fs_info = sbi;
662 
663 	/*
664 	 * See what the current blocksize for the device is, and
665 	 * use that as the blocksize.  Otherwise (or if the blocksize
666 	 * is smaller than the default) use the default.
667 	 * This is important for devices that have a hardware
668 	 * sectorsize that is larger than the default.
669 	 */
670 	blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
671 	if (!blocksize) {
672 		printk ("EXT2-fs: unable to set blocksize\n");
673 		goto failed_sbi;
674 	}
675 
676 	/*
677 	 * If the superblock doesn't start on a hardware sector boundary,
678 	 * calculate the offset.
679 	 */
680 	if (blocksize != BLOCK_SIZE) {
681 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
682 		offset = (sb_block*BLOCK_SIZE) % blocksize;
683 	} else {
684 		logic_sb_block = sb_block;
685 	}
686 
687 	if (!(bh = sb_bread(sb, logic_sb_block))) {
688 		printk ("EXT2-fs: unable to read superblock\n");
689 		goto failed_sbi;
690 	}
691 	/*
692 	 * Note: s_es must be initialized as soon as possible because
693 	 *       some ext2 macro-instructions depend on its value
694 	 */
695 	es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
696 	sbi->s_es = es;
697 	sb->s_magic = le16_to_cpu(es->s_magic);
698 
699 	if (sb->s_magic != EXT2_SUPER_MAGIC)
700 		goto cantfind_ext2;
701 
702 	/* Set defaults before we parse the mount options */
703 	def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
704 	if (def_mount_opts & EXT2_DEFM_DEBUG)
705 		set_opt(sbi->s_mount_opt, DEBUG);
706 	if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
707 		set_opt(sbi->s_mount_opt, GRPID);
708 	if (def_mount_opts & EXT2_DEFM_UID16)
709 		set_opt(sbi->s_mount_opt, NO_UID32);
710 #ifdef CONFIG_EXT2_FS_XATTR
711 	if (def_mount_opts & EXT2_DEFM_XATTR_USER)
712 		set_opt(sbi->s_mount_opt, XATTR_USER);
713 #endif
714 #ifdef CONFIG_EXT2_FS_POSIX_ACL
715 	if (def_mount_opts & EXT2_DEFM_ACL)
716 		set_opt(sbi->s_mount_opt, POSIX_ACL);
717 #endif
718 
719 	if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
720 		set_opt(sbi->s_mount_opt, ERRORS_PANIC);
721 	else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
722 		set_opt(sbi->s_mount_opt, ERRORS_RO);
723 	else
724 		set_opt(sbi->s_mount_opt, ERRORS_CONT);
725 
726 	sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
727 	sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
728 
729 	if (!parse_options ((char *) data, sbi))
730 		goto failed_mount;
731 
732 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
733 		((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
734 		 MS_POSIXACL : 0);
735 
736 	ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
737 				    EXT2_MOUNT_XIP if not */
738 
739 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
740 	    (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
741 	     EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
742 	     EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
743 		printk("EXT2-fs warning: feature flags set on rev 0 fs, "
744 		       "running e2fsck is recommended\n");
745 	/*
746 	 * Check feature flags regardless of the revision level, since we
747 	 * previously didn't change the revision level when setting the flags,
748 	 * so there is a chance incompat flags are set on a rev 0 filesystem.
749 	 */
750 	features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
751 	if (features) {
752 		printk("EXT2-fs: %s: couldn't mount because of "
753 		       "unsupported optional features (%x).\n",
754 		       sb->s_id, le32_to_cpu(features));
755 		goto failed_mount;
756 	}
757 	if (!(sb->s_flags & MS_RDONLY) &&
758 	    (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
759 		printk("EXT2-fs: %s: couldn't mount RDWR because of "
760 		       "unsupported optional features (%x).\n",
761 		       sb->s_id, le32_to_cpu(features));
762 		goto failed_mount;
763 	}
764 
765 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
766 
767 	if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
768 				  (sb->s_blocksize != blocksize))) {
769 		if (!silent)
770 			printk("XIP: Unsupported blocksize\n");
771 		goto failed_mount;
772 	}
773 
774 	/* If the blocksize doesn't match, re-read the thing.. */
775 	if (sb->s_blocksize != blocksize) {
776 		brelse(bh);
777 
778 		if (!sb_set_blocksize(sb, blocksize)) {
779 			printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
780 			goto failed_sbi;
781 		}
782 
783 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
784 		offset = (sb_block*BLOCK_SIZE) % blocksize;
785 		bh = sb_bread(sb, logic_sb_block);
786 		if(!bh) {
787 			printk("EXT2-fs: Couldn't read superblock on "
788 			       "2nd try.\n");
789 			goto failed_sbi;
790 		}
791 		es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
792 		sbi->s_es = es;
793 		if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
794 			printk ("EXT2-fs: Magic mismatch, very weird !\n");
795 			goto failed_mount;
796 		}
797 	}
798 
799 	sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
800 
801 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
802 		sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
803 		sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
804 	} else {
805 		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
806 		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
807 		if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
808 		    (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
809 		    (sbi->s_inode_size > blocksize)) {
810 			printk ("EXT2-fs: unsupported inode size: %d\n",
811 				sbi->s_inode_size);
812 			goto failed_mount;
813 		}
814 	}
815 
816 	sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
817 				   le32_to_cpu(es->s_log_frag_size);
818 	if (sbi->s_frag_size == 0)
819 		goto cantfind_ext2;
820 	sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
821 
822 	sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
823 	sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
824 	sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
825 
826 	if (EXT2_INODE_SIZE(sb) == 0)
827 		goto cantfind_ext2;
828 	sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
829 	if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
830 		goto cantfind_ext2;
831 	sbi->s_itb_per_group = sbi->s_inodes_per_group /
832 					sbi->s_inodes_per_block;
833 	sbi->s_desc_per_block = sb->s_blocksize /
834 					sizeof (struct ext2_group_desc);
835 	sbi->s_sbh = bh;
836 	sbi->s_mount_state = le16_to_cpu(es->s_state);
837 	sbi->s_addr_per_block_bits =
838 		ilog2 (EXT2_ADDR_PER_BLOCK(sb));
839 	sbi->s_desc_per_block_bits =
840 		ilog2 (EXT2_DESC_PER_BLOCK(sb));
841 
842 	if (sb->s_magic != EXT2_SUPER_MAGIC)
843 		goto cantfind_ext2;
844 
845 	if (sb->s_blocksize != bh->b_size) {
846 		if (!silent)
847 			printk ("VFS: Unsupported blocksize on dev "
848 				"%s.\n", sb->s_id);
849 		goto failed_mount;
850 	}
851 
852 	if (sb->s_blocksize != sbi->s_frag_size) {
853 		printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
854 			sbi->s_frag_size, sb->s_blocksize);
855 		goto failed_mount;
856 	}
857 
858 	if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
859 		printk ("EXT2-fs: #blocks per group too big: %lu\n",
860 			sbi->s_blocks_per_group);
861 		goto failed_mount;
862 	}
863 	if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
864 		printk ("EXT2-fs: #fragments per group too big: %lu\n",
865 			sbi->s_frags_per_group);
866 		goto failed_mount;
867 	}
868 	if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
869 		printk ("EXT2-fs: #inodes per group too big: %lu\n",
870 			sbi->s_inodes_per_group);
871 		goto failed_mount;
872 	}
873 
874 	if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
875 		goto cantfind_ext2;
876  	sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
877  				le32_to_cpu(es->s_first_data_block) - 1)
878  					/ EXT2_BLOCKS_PER_GROUP(sb)) + 1;
879 	db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
880 		   EXT2_DESC_PER_BLOCK(sb);
881 	sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
882 	if (sbi->s_group_desc == NULL) {
883 		printk ("EXT2-fs: not enough memory\n");
884 		goto failed_mount;
885 	}
886 	bgl_lock_init(&sbi->s_blockgroup_lock);
887 	sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
888 			       GFP_KERNEL);
889 	if (!sbi->s_debts) {
890 		printk ("EXT2-fs: not enough memory\n");
891 		goto failed_mount_group_desc;
892 	}
893 	memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
894 	for (i = 0; i < db_count; i++) {
895 		block = descriptor_loc(sb, logic_sb_block, i);
896 		sbi->s_group_desc[i] = sb_bread(sb, block);
897 		if (!sbi->s_group_desc[i]) {
898 			for (j = 0; j < i; j++)
899 				brelse (sbi->s_group_desc[j]);
900 			printk ("EXT2-fs: unable to read group descriptors\n");
901 			goto failed_mount_group_desc;
902 		}
903 	}
904 	if (!ext2_check_descriptors (sb)) {
905 		printk ("EXT2-fs: group descriptors corrupted!\n");
906 		goto failed_mount2;
907 	}
908 	sbi->s_gdb_count = db_count;
909 	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
910 	spin_lock_init(&sbi->s_next_gen_lock);
911 
912 	percpu_counter_init(&sbi->s_freeblocks_counter,
913 				ext2_count_free_blocks(sb));
914 	percpu_counter_init(&sbi->s_freeinodes_counter,
915 				ext2_count_free_inodes(sb));
916 	percpu_counter_init(&sbi->s_dirs_counter,
917 				ext2_count_dirs(sb));
918 	/*
919 	 * set up enough so that it can read an inode
920 	 */
921 	sb->s_op = &ext2_sops;
922 	sb->s_export_op = &ext2_export_ops;
923 	sb->s_xattr = ext2_xattr_handlers;
924 	root = iget(sb, EXT2_ROOT_INO);
925 	sb->s_root = d_alloc_root(root);
926 	if (!sb->s_root) {
927 		iput(root);
928 		printk(KERN_ERR "EXT2-fs: get root inode failed\n");
929 		goto failed_mount3;
930 	}
931 	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
932 		dput(sb->s_root);
933 		sb->s_root = NULL;
934 		printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
935 		goto failed_mount3;
936 	}
937 	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
938 		ext2_warning(sb, __FUNCTION__,
939 			"mounting ext3 filesystem as ext2");
940 	ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
941 	return 0;
942 
943 cantfind_ext2:
944 	if (!silent)
945 		printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
946 		       sb->s_id);
947 	goto failed_mount;
948 failed_mount3:
949 	percpu_counter_destroy(&sbi->s_freeblocks_counter);
950 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
951 	percpu_counter_destroy(&sbi->s_dirs_counter);
952 failed_mount2:
953 	for (i = 0; i < db_count; i++)
954 		brelse(sbi->s_group_desc[i]);
955 failed_mount_group_desc:
956 	kfree(sbi->s_group_desc);
957 	kfree(sbi->s_debts);
958 failed_mount:
959 	brelse(bh);
960 failed_sbi:
961 	sb->s_fs_info = NULL;
962 	kfree(sbi);
963 	return -EINVAL;
964 }
965 
966 static void ext2_commit_super (struct super_block * sb,
967 			       struct ext2_super_block * es)
968 {
969 	es->s_wtime = cpu_to_le32(get_seconds());
970 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
971 	sb->s_dirt = 0;
972 }
973 
974 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
975 {
976 	es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
977 	es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
978 	es->s_wtime = cpu_to_le32(get_seconds());
979 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
980 	sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
981 	sb->s_dirt = 0;
982 }
983 
984 /*
985  * In the second extended file system, it is not necessary to
986  * write the super block since we use a mapping of the
987  * disk super block in a buffer.
988  *
989  * However, this function is still used to set the fs valid
990  * flags to 0.  We need to set this flag to 0 since the fs
991  * may have been checked while mounted and e2fsck may have
992  * set s_state to EXT2_VALID_FS after some corrections.
993  */
994 
995 void ext2_write_super (struct super_block * sb)
996 {
997 	struct ext2_super_block * es;
998 	lock_kernel();
999 	if (!(sb->s_flags & MS_RDONLY)) {
1000 		es = EXT2_SB(sb)->s_es;
1001 
1002 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1003 			ext2_debug ("setting valid to 0\n");
1004 			es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1005 						  ~EXT2_VALID_FS);
1006 			es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1007 			es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1008 			es->s_mtime = cpu_to_le32(get_seconds());
1009 			ext2_sync_super(sb, es);
1010 		} else
1011 			ext2_commit_super (sb, es);
1012 	}
1013 	sb->s_dirt = 0;
1014 	unlock_kernel();
1015 }
1016 
1017 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1018 {
1019 	struct ext2_sb_info * sbi = EXT2_SB(sb);
1020 	struct ext2_super_block * es;
1021 	unsigned long old_mount_opt = sbi->s_mount_opt;
1022 	struct ext2_mount_options old_opts;
1023 	unsigned long old_sb_flags;
1024 	int err;
1025 
1026 	/* Store the old options */
1027 	old_sb_flags = sb->s_flags;
1028 	old_opts.s_mount_opt = sbi->s_mount_opt;
1029 	old_opts.s_resuid = sbi->s_resuid;
1030 	old_opts.s_resgid = sbi->s_resgid;
1031 
1032 	/*
1033 	 * Allow the "check" option to be passed as a remount option.
1034 	 */
1035 	if (!parse_options (data, sbi)) {
1036 		err = -EINVAL;
1037 		goto restore_opts;
1038 	}
1039 
1040 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1041 		((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1042 
1043 	es = sbi->s_es;
1044 	if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1045 	    (old_mount_opt & EXT2_MOUNT_XIP)) &&
1046 	    invalidate_inodes(sb))
1047 		ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1048 			     "xip remain in cache (no functional problem)");
1049 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1050 		return 0;
1051 	if (*flags & MS_RDONLY) {
1052 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1053 		    !(sbi->s_mount_state & EXT2_VALID_FS))
1054 			return 0;
1055 		/*
1056 		 * OK, we are remounting a valid rw partition rdonly, so set
1057 		 * the rdonly flag and then mark the partition as valid again.
1058 		 */
1059 		es->s_state = cpu_to_le16(sbi->s_mount_state);
1060 		es->s_mtime = cpu_to_le32(get_seconds());
1061 	} else {
1062 		__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1063 					       ~EXT2_FEATURE_RO_COMPAT_SUPP);
1064 		if (ret) {
1065 			printk("EXT2-fs: %s: couldn't remount RDWR because of "
1066 			       "unsupported optional features (%x).\n",
1067 			       sb->s_id, le32_to_cpu(ret));
1068 			err = -EROFS;
1069 			goto restore_opts;
1070 		}
1071 		/*
1072 		 * Mounting a RDONLY partition read-write, so reread and
1073 		 * store the current valid flag.  (It may have been changed
1074 		 * by e2fsck since we originally mounted the partition.)
1075 		 */
1076 		sbi->s_mount_state = le16_to_cpu(es->s_state);
1077 		if (!ext2_setup_super (sb, es, 0))
1078 			sb->s_flags &= ~MS_RDONLY;
1079 	}
1080 	ext2_sync_super(sb, es);
1081 	return 0;
1082 restore_opts:
1083 	sbi->s_mount_opt = old_opts.s_mount_opt;
1084 	sbi->s_resuid = old_opts.s_resuid;
1085 	sbi->s_resgid = old_opts.s_resgid;
1086 	sb->s_flags = old_sb_flags;
1087 	return err;
1088 }
1089 
1090 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1091 {
1092 	struct super_block *sb = dentry->d_sb;
1093 	struct ext2_sb_info *sbi = EXT2_SB(sb);
1094 	struct ext2_super_block *es = sbi->s_es;
1095 	unsigned long overhead;
1096 	int i;
1097 	u64 fsid;
1098 
1099 	if (test_opt (sb, MINIX_DF))
1100 		overhead = 0;
1101 	else {
1102 		/*
1103 		 * Compute the overhead (FS structures)
1104 		 */
1105 
1106 		/*
1107 		 * All of the blocks before first_data_block are
1108 		 * overhead
1109 		 */
1110 		overhead = le32_to_cpu(es->s_first_data_block);
1111 
1112 		/*
1113 		 * Add the overhead attributed to the superblock and
1114 		 * block group descriptors.  If the sparse superblocks
1115 		 * feature is turned on, then not all groups have this.
1116 		 */
1117 		for (i = 0; i < sbi->s_groups_count; i++)
1118 			overhead += ext2_bg_has_super(sb, i) +
1119 				ext2_bg_num_gdb(sb, i);
1120 
1121 		/*
1122 		 * Every block group has an inode bitmap, a block
1123 		 * bitmap, and an inode table.
1124 		 */
1125 		overhead += (sbi->s_groups_count *
1126 			     (2 + sbi->s_itb_per_group));
1127 	}
1128 
1129 	buf->f_type = EXT2_SUPER_MAGIC;
1130 	buf->f_bsize = sb->s_blocksize;
1131 	buf->f_blocks = le32_to_cpu(es->s_blocks_count) - overhead;
1132 	buf->f_bfree = ext2_count_free_blocks(sb);
1133 	buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
1134 	if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
1135 		buf->f_bavail = 0;
1136 	buf->f_files = le32_to_cpu(es->s_inodes_count);
1137 	buf->f_ffree = ext2_count_free_inodes(sb);
1138 	buf->f_namelen = EXT2_NAME_LEN;
1139 	fsid = le64_to_cpup((void *)es->s_uuid) ^
1140 	       le64_to_cpup((void *)es->s_uuid + sizeof(u64));
1141 	buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
1142 	buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
1143 	return 0;
1144 }
1145 
1146 static int ext2_get_sb(struct file_system_type *fs_type,
1147 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1148 {
1149 	return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1150 }
1151 
1152 #ifdef CONFIG_QUOTA
1153 
1154 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1155  * acquiring the locks... As quota files are never truncated and quota code
1156  * itself serializes the operations (and noone else should touch the files)
1157  * we don't have to be afraid of races */
1158 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1159 			       size_t len, loff_t off)
1160 {
1161 	struct inode *inode = sb_dqopt(sb)->files[type];
1162 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1163 	int err = 0;
1164 	int offset = off & (sb->s_blocksize - 1);
1165 	int tocopy;
1166 	size_t toread;
1167 	struct buffer_head tmp_bh;
1168 	struct buffer_head *bh;
1169 	loff_t i_size = i_size_read(inode);
1170 
1171 	if (off > i_size)
1172 		return 0;
1173 	if (off+len > i_size)
1174 		len = i_size-off;
1175 	toread = len;
1176 	while (toread > 0) {
1177 		tocopy = sb->s_blocksize - offset < toread ?
1178 				sb->s_blocksize - offset : toread;
1179 
1180 		tmp_bh.b_state = 0;
1181 		err = ext2_get_block(inode, blk, &tmp_bh, 0);
1182 		if (err)
1183 			return err;
1184 		if (!buffer_mapped(&tmp_bh))	/* A hole? */
1185 			memset(data, 0, tocopy);
1186 		else {
1187 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1188 			if (!bh)
1189 				return -EIO;
1190 			memcpy(data, bh->b_data+offset, tocopy);
1191 			brelse(bh);
1192 		}
1193 		offset = 0;
1194 		toread -= tocopy;
1195 		data += tocopy;
1196 		blk++;
1197 	}
1198 	return len;
1199 }
1200 
1201 /* Write to quotafile */
1202 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1203 				const char *data, size_t len, loff_t off)
1204 {
1205 	struct inode *inode = sb_dqopt(sb)->files[type];
1206 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1207 	int err = 0;
1208 	int offset = off & (sb->s_blocksize - 1);
1209 	int tocopy;
1210 	size_t towrite = len;
1211 	struct buffer_head tmp_bh;
1212 	struct buffer_head *bh;
1213 
1214 	mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1215 	while (towrite > 0) {
1216 		tocopy = sb->s_blocksize - offset < towrite ?
1217 				sb->s_blocksize - offset : towrite;
1218 
1219 		tmp_bh.b_state = 0;
1220 		err = ext2_get_block(inode, blk, &tmp_bh, 1);
1221 		if (err)
1222 			goto out;
1223 		if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1224 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1225 		else
1226 			bh = sb_getblk(sb, tmp_bh.b_blocknr);
1227 		if (!bh) {
1228 			err = -EIO;
1229 			goto out;
1230 		}
1231 		lock_buffer(bh);
1232 		memcpy(bh->b_data+offset, data, tocopy);
1233 		flush_dcache_page(bh->b_page);
1234 		set_buffer_uptodate(bh);
1235 		mark_buffer_dirty(bh);
1236 		unlock_buffer(bh);
1237 		brelse(bh);
1238 		offset = 0;
1239 		towrite -= tocopy;
1240 		data += tocopy;
1241 		blk++;
1242 	}
1243 out:
1244 	if (len == towrite)
1245 		return err;
1246 	if (inode->i_size < off+len-towrite)
1247 		i_size_write(inode, off+len-towrite);
1248 	inode->i_version++;
1249 	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1250 	mark_inode_dirty(inode);
1251 	mutex_unlock(&inode->i_mutex);
1252 	return len - towrite;
1253 }
1254 
1255 #endif
1256 
1257 static struct file_system_type ext2_fs_type = {
1258 	.owner		= THIS_MODULE,
1259 	.name		= "ext2",
1260 	.get_sb		= ext2_get_sb,
1261 	.kill_sb	= kill_block_super,
1262 	.fs_flags	= FS_REQUIRES_DEV,
1263 };
1264 
1265 static int __init init_ext2_fs(void)
1266 {
1267 	int err = init_ext2_xattr();
1268 	if (err)
1269 		return err;
1270 	err = init_inodecache();
1271 	if (err)
1272 		goto out1;
1273         err = register_filesystem(&ext2_fs_type);
1274 	if (err)
1275 		goto out;
1276 	return 0;
1277 out:
1278 	destroy_inodecache();
1279 out1:
1280 	exit_ext2_xattr();
1281 	return err;
1282 }
1283 
1284 static void __exit exit_ext2_fs(void)
1285 {
1286 	unregister_filesystem(&ext2_fs_type);
1287 	destroy_inodecache();
1288 	exit_ext2_xattr();
1289 }
1290 
1291 module_init(init_ext2_fs)
1292 module_exit(exit_ext2_fs)
1293