xref: /linux/fs/ext2/super.c (revision 14b42963f64b98ab61fa9723c03d71aa5ef4f862)
1 /*
2  *  linux/fs/ext2/super.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  Big-endian to little-endian byte-swapping/bitmaps by
16  *        David S. Miller (davem@caip.rutgers.edu), 1995
17  */
18 
19 #include <linux/module.h>
20 #include <linux/string.h>
21 #include <linux/fs.h>
22 #include <linux/slab.h>
23 #include <linux/init.h>
24 #include <linux/blkdev.h>
25 #include <linux/parser.h>
26 #include <linux/random.h>
27 #include <linux/buffer_head.h>
28 #include <linux/smp_lock.h>
29 #include <linux/vfs.h>
30 #include <linux/seq_file.h>
31 #include <linux/mount.h>
32 #include <asm/uaccess.h>
33 #include "ext2.h"
34 #include "xattr.h"
35 #include "acl.h"
36 #include "xip.h"
37 
38 static void ext2_sync_super(struct super_block *sb,
39 			    struct ext2_super_block *es);
40 static int ext2_remount (struct super_block * sb, int * flags, char * data);
41 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
42 
43 void ext2_error (struct super_block * sb, const char * function,
44 		 const char * fmt, ...)
45 {
46 	va_list args;
47 	struct ext2_sb_info *sbi = EXT2_SB(sb);
48 	struct ext2_super_block *es = sbi->s_es;
49 
50 	if (!(sb->s_flags & MS_RDONLY)) {
51 		sbi->s_mount_state |= EXT2_ERROR_FS;
52 		es->s_state =
53 			cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
54 		ext2_sync_super(sb, es);
55 	}
56 
57 	va_start(args, fmt);
58 	printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
59 	vprintk(fmt, args);
60 	printk("\n");
61 	va_end(args);
62 
63 	if (test_opt(sb, ERRORS_PANIC))
64 		panic("EXT2-fs panic from previous error\n");
65 	if (test_opt(sb, ERRORS_RO)) {
66 		printk("Remounting filesystem read-only\n");
67 		sb->s_flags |= MS_RDONLY;
68 	}
69 }
70 
71 void ext2_warning (struct super_block * sb, const char * function,
72 		   const char * fmt, ...)
73 {
74 	va_list args;
75 
76 	va_start(args, fmt);
77 	printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
78 	       sb->s_id, function);
79 	vprintk(fmt, args);
80 	printk("\n");
81 	va_end(args);
82 }
83 
84 void ext2_update_dynamic_rev(struct super_block *sb)
85 {
86 	struct ext2_super_block *es = EXT2_SB(sb)->s_es;
87 
88 	if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
89 		return;
90 
91 	ext2_warning(sb, __FUNCTION__,
92 		     "updating to rev %d because of new feature flag, "
93 		     "running e2fsck is recommended",
94 		     EXT2_DYNAMIC_REV);
95 
96 	es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
97 	es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
98 	es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
99 	/* leave es->s_feature_*compat flags alone */
100 	/* es->s_uuid will be set by e2fsck if empty */
101 
102 	/*
103 	 * The rest of the superblock fields should be zero, and if not it
104 	 * means they are likely already in use, so leave them alone.  We
105 	 * can leave it up to e2fsck to clean up any inconsistencies there.
106 	 */
107 }
108 
109 static void ext2_put_super (struct super_block * sb)
110 {
111 	int db_count;
112 	int i;
113 	struct ext2_sb_info *sbi = EXT2_SB(sb);
114 
115 	ext2_xattr_put_super(sb);
116 	if (!(sb->s_flags & MS_RDONLY)) {
117 		struct ext2_super_block *es = sbi->s_es;
118 
119 		es->s_state = cpu_to_le16(sbi->s_mount_state);
120 		ext2_sync_super(sb, es);
121 	}
122 	db_count = sbi->s_gdb_count;
123 	for (i = 0; i < db_count; i++)
124 		if (sbi->s_group_desc[i])
125 			brelse (sbi->s_group_desc[i]);
126 	kfree(sbi->s_group_desc);
127 	kfree(sbi->s_debts);
128 	percpu_counter_destroy(&sbi->s_freeblocks_counter);
129 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
130 	percpu_counter_destroy(&sbi->s_dirs_counter);
131 	brelse (sbi->s_sbh);
132 	sb->s_fs_info = NULL;
133 	kfree(sbi);
134 
135 	return;
136 }
137 
138 static kmem_cache_t * ext2_inode_cachep;
139 
140 static struct inode *ext2_alloc_inode(struct super_block *sb)
141 {
142 	struct ext2_inode_info *ei;
143 	ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL);
144 	if (!ei)
145 		return NULL;
146 #ifdef CONFIG_EXT2_FS_POSIX_ACL
147 	ei->i_acl = EXT2_ACL_NOT_CACHED;
148 	ei->i_default_acl = EXT2_ACL_NOT_CACHED;
149 #endif
150 	ei->vfs_inode.i_version = 1;
151 	return &ei->vfs_inode;
152 }
153 
154 static void ext2_destroy_inode(struct inode *inode)
155 {
156 	kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
157 }
158 
159 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
160 {
161 	struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
162 
163 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
164 	    SLAB_CTOR_CONSTRUCTOR) {
165 		rwlock_init(&ei->i_meta_lock);
166 #ifdef CONFIG_EXT2_FS_XATTR
167 		init_rwsem(&ei->xattr_sem);
168 #endif
169 		inode_init_once(&ei->vfs_inode);
170 	}
171 }
172 
173 static int init_inodecache(void)
174 {
175 	ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
176 					     sizeof(struct ext2_inode_info),
177 					     0, (SLAB_RECLAIM_ACCOUNT|
178 						SLAB_MEM_SPREAD),
179 					     init_once, NULL);
180 	if (ext2_inode_cachep == NULL)
181 		return -ENOMEM;
182 	return 0;
183 }
184 
185 static void destroy_inodecache(void)
186 {
187 	if (kmem_cache_destroy(ext2_inode_cachep))
188 		printk(KERN_INFO "ext2_inode_cache: not all structures were freed\n");
189 }
190 
191 static void ext2_clear_inode(struct inode *inode)
192 {
193 #ifdef CONFIG_EXT2_FS_POSIX_ACL
194 	struct ext2_inode_info *ei = EXT2_I(inode);
195 
196 	if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
197 		posix_acl_release(ei->i_acl);
198 		ei->i_acl = EXT2_ACL_NOT_CACHED;
199 	}
200 	if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
201 		posix_acl_release(ei->i_default_acl);
202 		ei->i_default_acl = EXT2_ACL_NOT_CACHED;
203 	}
204 #endif
205 }
206 
207 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
208 {
209 	struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
210 
211 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
212 		seq_puts(seq, ",grpid");
213 
214 #if defined(CONFIG_QUOTA)
215 	if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
216 		seq_puts(seq, ",usrquota");
217 
218 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
219 		seq_puts(seq, ",grpquota");
220 #endif
221 
222 #if defined(CONFIG_EXT2_FS_XIP)
223 	if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
224 		seq_puts(seq, ",xip");
225 #endif
226 
227 	return 0;
228 }
229 
230 #ifdef CONFIG_QUOTA
231 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
232 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
233 #endif
234 
235 static struct super_operations ext2_sops = {
236 	.alloc_inode	= ext2_alloc_inode,
237 	.destroy_inode	= ext2_destroy_inode,
238 	.read_inode	= ext2_read_inode,
239 	.write_inode	= ext2_write_inode,
240 	.put_inode	= ext2_put_inode,
241 	.delete_inode	= ext2_delete_inode,
242 	.put_super	= ext2_put_super,
243 	.write_super	= ext2_write_super,
244 	.statfs		= ext2_statfs,
245 	.remount_fs	= ext2_remount,
246 	.clear_inode	= ext2_clear_inode,
247 	.show_options	= ext2_show_options,
248 #ifdef CONFIG_QUOTA
249 	.quota_read	= ext2_quota_read,
250 	.quota_write	= ext2_quota_write,
251 #endif
252 };
253 
254 /* Yes, most of these are left as NULL!!
255  * A NULL value implies the default, which works with ext2-like file
256  * systems, but can be improved upon.
257  * Currently only get_parent is required.
258  */
259 static struct export_operations ext2_export_ops = {
260 	.get_parent = ext2_get_parent,
261 };
262 
263 static unsigned long get_sb_block(void **data)
264 {
265 	unsigned long 	sb_block;
266 	char 		*options = (char *) *data;
267 
268 	if (!options || strncmp(options, "sb=", 3) != 0)
269 		return 1;	/* Default location */
270 	options += 3;
271 	sb_block = simple_strtoul(options, &options, 0);
272 	if (*options && *options != ',') {
273 		printk("EXT2-fs: Invalid sb specification: %s\n",
274 		       (char *) *data);
275 		return 1;
276 	}
277 	if (*options == ',')
278 		options++;
279 	*data = (void *) options;
280 	return sb_block;
281 }
282 
283 enum {
284 	Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
285 	Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
286 	Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
287 	Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
288 	Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
289 	Opt_usrquota, Opt_grpquota
290 };
291 
292 static match_table_t tokens = {
293 	{Opt_bsd_df, "bsddf"},
294 	{Opt_minix_df, "minixdf"},
295 	{Opt_grpid, "grpid"},
296 	{Opt_grpid, "bsdgroups"},
297 	{Opt_nogrpid, "nogrpid"},
298 	{Opt_nogrpid, "sysvgroups"},
299 	{Opt_resgid, "resgid=%u"},
300 	{Opt_resuid, "resuid=%u"},
301 	{Opt_sb, "sb=%u"},
302 	{Opt_err_cont, "errors=continue"},
303 	{Opt_err_panic, "errors=panic"},
304 	{Opt_err_ro, "errors=remount-ro"},
305 	{Opt_nouid32, "nouid32"},
306 	{Opt_nocheck, "check=none"},
307 	{Opt_nocheck, "nocheck"},
308 	{Opt_debug, "debug"},
309 	{Opt_oldalloc, "oldalloc"},
310 	{Opt_orlov, "orlov"},
311 	{Opt_nobh, "nobh"},
312 	{Opt_user_xattr, "user_xattr"},
313 	{Opt_nouser_xattr, "nouser_xattr"},
314 	{Opt_acl, "acl"},
315 	{Opt_noacl, "noacl"},
316 	{Opt_xip, "xip"},
317 	{Opt_grpquota, "grpquota"},
318 	{Opt_ignore, "noquota"},
319 	{Opt_quota, "quota"},
320 	{Opt_usrquota, "usrquota"},
321 	{Opt_err, NULL}
322 };
323 
324 static int parse_options (char * options,
325 			  struct ext2_sb_info *sbi)
326 {
327 	char * p;
328 	substring_t args[MAX_OPT_ARGS];
329 	unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
330 	int option;
331 
332 	if (!options)
333 		return 1;
334 
335 	while ((p = strsep (&options, ",")) != NULL) {
336 		int token;
337 		if (!*p)
338 			continue;
339 
340 		token = match_token(p, tokens, args);
341 		switch (token) {
342 		case Opt_bsd_df:
343 			clear_opt (sbi->s_mount_opt, MINIX_DF);
344 			break;
345 		case Opt_minix_df:
346 			set_opt (sbi->s_mount_opt, MINIX_DF);
347 			break;
348 		case Opt_grpid:
349 			set_opt (sbi->s_mount_opt, GRPID);
350 			break;
351 		case Opt_nogrpid:
352 			clear_opt (sbi->s_mount_opt, GRPID);
353 			break;
354 		case Opt_resuid:
355 			if (match_int(&args[0], &option))
356 				return 0;
357 			sbi->s_resuid = option;
358 			break;
359 		case Opt_resgid:
360 			if (match_int(&args[0], &option))
361 				return 0;
362 			sbi->s_resgid = option;
363 			break;
364 		case Opt_sb:
365 			/* handled by get_sb_block() instead of here */
366 			/* *sb_block = match_int(&args[0]); */
367 			break;
368 		case Opt_err_panic:
369 			kind = EXT2_MOUNT_ERRORS_PANIC;
370 			break;
371 		case Opt_err_ro:
372 			kind = EXT2_MOUNT_ERRORS_RO;
373 			break;
374 		case Opt_err_cont:
375 			kind = EXT2_MOUNT_ERRORS_CONT;
376 			break;
377 		case Opt_nouid32:
378 			set_opt (sbi->s_mount_opt, NO_UID32);
379 			break;
380 		case Opt_nocheck:
381 			clear_opt (sbi->s_mount_opt, CHECK);
382 			break;
383 		case Opt_debug:
384 			set_opt (sbi->s_mount_opt, DEBUG);
385 			break;
386 		case Opt_oldalloc:
387 			set_opt (sbi->s_mount_opt, OLDALLOC);
388 			break;
389 		case Opt_orlov:
390 			clear_opt (sbi->s_mount_opt, OLDALLOC);
391 			break;
392 		case Opt_nobh:
393 			set_opt (sbi->s_mount_opt, NOBH);
394 			break;
395 #ifdef CONFIG_EXT2_FS_XATTR
396 		case Opt_user_xattr:
397 			set_opt (sbi->s_mount_opt, XATTR_USER);
398 			break;
399 		case Opt_nouser_xattr:
400 			clear_opt (sbi->s_mount_opt, XATTR_USER);
401 			break;
402 #else
403 		case Opt_user_xattr:
404 		case Opt_nouser_xattr:
405 			printk("EXT2 (no)user_xattr options not supported\n");
406 			break;
407 #endif
408 #ifdef CONFIG_EXT2_FS_POSIX_ACL
409 		case Opt_acl:
410 			set_opt(sbi->s_mount_opt, POSIX_ACL);
411 			break;
412 		case Opt_noacl:
413 			clear_opt(sbi->s_mount_opt, POSIX_ACL);
414 			break;
415 #else
416 		case Opt_acl:
417 		case Opt_noacl:
418 			printk("EXT2 (no)acl options not supported\n");
419 			break;
420 #endif
421 		case Opt_xip:
422 #ifdef CONFIG_EXT2_FS_XIP
423 			set_opt (sbi->s_mount_opt, XIP);
424 #else
425 			printk("EXT2 xip option not supported\n");
426 #endif
427 			break;
428 
429 #if defined(CONFIG_QUOTA)
430 		case Opt_quota:
431 		case Opt_usrquota:
432 			set_opt(sbi->s_mount_opt, USRQUOTA);
433 			break;
434 
435 		case Opt_grpquota:
436 			set_opt(sbi->s_mount_opt, GRPQUOTA);
437 			break;
438 #else
439 		case Opt_quota:
440 		case Opt_usrquota:
441 		case Opt_grpquota:
442 			printk(KERN_ERR
443 				"EXT2-fs: quota operations not supported.\n");
444 
445 			break;
446 #endif
447 
448 		case Opt_ignore:
449 			break;
450 		default:
451 			return 0;
452 		}
453 	}
454 	sbi->s_mount_opt |= kind;
455 	return 1;
456 }
457 
458 static int ext2_setup_super (struct super_block * sb,
459 			      struct ext2_super_block * es,
460 			      int read_only)
461 {
462 	int res = 0;
463 	struct ext2_sb_info *sbi = EXT2_SB(sb);
464 
465 	if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
466 		printk ("EXT2-fs warning: revision level too high, "
467 			"forcing read-only mode\n");
468 		res = MS_RDONLY;
469 	}
470 	if (read_only)
471 		return res;
472 	if (!(sbi->s_mount_state & EXT2_VALID_FS))
473 		printk ("EXT2-fs warning: mounting unchecked fs, "
474 			"running e2fsck is recommended\n");
475 	else if ((sbi->s_mount_state & EXT2_ERROR_FS))
476 		printk ("EXT2-fs warning: mounting fs with errors, "
477 			"running e2fsck is recommended\n");
478 	else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
479 		 le16_to_cpu(es->s_mnt_count) >=
480 		 (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
481 		printk ("EXT2-fs warning: maximal mount count reached, "
482 			"running e2fsck is recommended\n");
483 	else if (le32_to_cpu(es->s_checkinterval) &&
484 		(le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
485 		printk ("EXT2-fs warning: checktime reached, "
486 			"running e2fsck is recommended\n");
487 	if (!le16_to_cpu(es->s_max_mnt_count))
488 		es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
489 	es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
490 	ext2_write_super(sb);
491 	if (test_opt (sb, DEBUG))
492 		printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
493 			"bpg=%lu, ipg=%lu, mo=%04lx]\n",
494 			EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
495 			sbi->s_frag_size,
496 			sbi->s_groups_count,
497 			EXT2_BLOCKS_PER_GROUP(sb),
498 			EXT2_INODES_PER_GROUP(sb),
499 			sbi->s_mount_opt);
500 	return res;
501 }
502 
503 static int ext2_check_descriptors (struct super_block * sb)
504 {
505 	int i;
506 	int desc_block = 0;
507 	struct ext2_sb_info *sbi = EXT2_SB(sb);
508 	unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
509 	struct ext2_group_desc * gdp = NULL;
510 
511 	ext2_debug ("Checking group descriptors");
512 
513 	for (i = 0; i < sbi->s_groups_count; i++)
514 	{
515 		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
516 			gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
517 		if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
518 		    le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
519 		{
520 			ext2_error (sb, "ext2_check_descriptors",
521 				    "Block bitmap for group %d"
522 				    " not in group (block %lu)!",
523 				    i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
524 			return 0;
525 		}
526 		if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
527 		    le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
528 		{
529 			ext2_error (sb, "ext2_check_descriptors",
530 				    "Inode bitmap for group %d"
531 				    " not in group (block %lu)!",
532 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
533 			return 0;
534 		}
535 		if (le32_to_cpu(gdp->bg_inode_table) < block ||
536 		    le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
537 		    block + EXT2_BLOCKS_PER_GROUP(sb))
538 		{
539 			ext2_error (sb, "ext2_check_descriptors",
540 				    "Inode table for group %d"
541 				    " not in group (block %lu)!",
542 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
543 			return 0;
544 		}
545 		block += EXT2_BLOCKS_PER_GROUP(sb);
546 		gdp++;
547 	}
548 	return 1;
549 }
550 
551 #define log2(n) ffz(~(n))
552 
553 /*
554  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
555  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
556  * We need to be 1 filesystem block less than the 2^32 sector limit.
557  */
558 static loff_t ext2_max_size(int bits)
559 {
560 	loff_t res = EXT2_NDIR_BLOCKS;
561 	/* This constant is calculated to be the largest file size for a
562 	 * dense, 4k-blocksize file such that the total number of
563 	 * sectors in the file, including data and all indirect blocks,
564 	 * does not exceed 2^32. */
565 	const loff_t upper_limit = 0x1ff7fffd000LL;
566 
567 	res += 1LL << (bits-2);
568 	res += 1LL << (2*(bits-2));
569 	res += 1LL << (3*(bits-2));
570 	res <<= bits;
571 	if (res > upper_limit)
572 		res = upper_limit;
573 	return res;
574 }
575 
576 static unsigned long descriptor_loc(struct super_block *sb,
577 				    unsigned long logic_sb_block,
578 				    int nr)
579 {
580 	struct ext2_sb_info *sbi = EXT2_SB(sb);
581 	unsigned long bg, first_data_block, first_meta_bg;
582 	int has_super = 0;
583 
584 	first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
585 	first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
586 
587 	if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
588 	    nr < first_meta_bg)
589 		return (logic_sb_block + nr + 1);
590 	bg = sbi->s_desc_per_block * nr;
591 	if (ext2_bg_has_super(sb, bg))
592 		has_super = 1;
593 	return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
594 }
595 
596 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
597 {
598 	struct buffer_head * bh;
599 	struct ext2_sb_info * sbi;
600 	struct ext2_super_block * es;
601 	struct inode *root;
602 	unsigned long block;
603 	unsigned long sb_block = get_sb_block(&data);
604 	unsigned long logic_sb_block;
605 	unsigned long offset = 0;
606 	unsigned long def_mount_opts;
607 	int blocksize = BLOCK_SIZE;
608 	int db_count;
609 	int i, j;
610 	__le32 features;
611 
612 	sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
613 	if (!sbi)
614 		return -ENOMEM;
615 	sb->s_fs_info = sbi;
616 	memset(sbi, 0, sizeof(*sbi));
617 
618 	/*
619 	 * See what the current blocksize for the device is, and
620 	 * use that as the blocksize.  Otherwise (or if the blocksize
621 	 * is smaller than the default) use the default.
622 	 * This is important for devices that have a hardware
623 	 * sectorsize that is larger than the default.
624 	 */
625 	blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
626 	if (!blocksize) {
627 		printk ("EXT2-fs: unable to set blocksize\n");
628 		goto failed_sbi;
629 	}
630 
631 	/*
632 	 * If the superblock doesn't start on a hardware sector boundary,
633 	 * calculate the offset.
634 	 */
635 	if (blocksize != BLOCK_SIZE) {
636 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
637 		offset = (sb_block*BLOCK_SIZE) % blocksize;
638 	} else {
639 		logic_sb_block = sb_block;
640 	}
641 
642 	if (!(bh = sb_bread(sb, logic_sb_block))) {
643 		printk ("EXT2-fs: unable to read superblock\n");
644 		goto failed_sbi;
645 	}
646 	/*
647 	 * Note: s_es must be initialized as soon as possible because
648 	 *       some ext2 macro-instructions depend on its value
649 	 */
650 	es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
651 	sbi->s_es = es;
652 	sb->s_magic = le16_to_cpu(es->s_magic);
653 
654 	if (sb->s_magic != EXT2_SUPER_MAGIC)
655 		goto cantfind_ext2;
656 
657 	/* Set defaults before we parse the mount options */
658 	def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
659 	if (def_mount_opts & EXT2_DEFM_DEBUG)
660 		set_opt(sbi->s_mount_opt, DEBUG);
661 	if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
662 		set_opt(sbi->s_mount_opt, GRPID);
663 	if (def_mount_opts & EXT2_DEFM_UID16)
664 		set_opt(sbi->s_mount_opt, NO_UID32);
665 	if (def_mount_opts & EXT2_DEFM_XATTR_USER)
666 		set_opt(sbi->s_mount_opt, XATTR_USER);
667 	if (def_mount_opts & EXT2_DEFM_ACL)
668 		set_opt(sbi->s_mount_opt, POSIX_ACL);
669 
670 	if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
671 		set_opt(sbi->s_mount_opt, ERRORS_PANIC);
672 	else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
673 		set_opt(sbi->s_mount_opt, ERRORS_RO);
674 
675 	sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
676 	sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
677 
678 	if (!parse_options ((char *) data, sbi))
679 		goto failed_mount;
680 
681 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
682 		((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
683 		 MS_POSIXACL : 0);
684 
685 	ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
686 				    EXT2_MOUNT_XIP if not */
687 
688 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
689 	    (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
690 	     EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
691 	     EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
692 		printk("EXT2-fs warning: feature flags set on rev 0 fs, "
693 		       "running e2fsck is recommended\n");
694 	/*
695 	 * Check feature flags regardless of the revision level, since we
696 	 * previously didn't change the revision level when setting the flags,
697 	 * so there is a chance incompat flags are set on a rev 0 filesystem.
698 	 */
699 	features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
700 	if (features) {
701 		printk("EXT2-fs: %s: couldn't mount because of "
702 		       "unsupported optional features (%x).\n",
703 		       sb->s_id, le32_to_cpu(features));
704 		goto failed_mount;
705 	}
706 	if (!(sb->s_flags & MS_RDONLY) &&
707 	    (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
708 		printk("EXT2-fs: %s: couldn't mount RDWR because of "
709 		       "unsupported optional features (%x).\n",
710 		       sb->s_id, le32_to_cpu(features));
711 		goto failed_mount;
712 	}
713 
714 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
715 
716 	if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
717 				  (sb->s_blocksize != blocksize))) {
718 		if (!silent)
719 			printk("XIP: Unsupported blocksize\n");
720 		goto failed_mount;
721 	}
722 
723 	/* If the blocksize doesn't match, re-read the thing.. */
724 	if (sb->s_blocksize != blocksize) {
725 		brelse(bh);
726 
727 		if (!sb_set_blocksize(sb, blocksize)) {
728 			printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
729 			goto failed_sbi;
730 		}
731 
732 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
733 		offset = (sb_block*BLOCK_SIZE) % blocksize;
734 		bh = sb_bread(sb, logic_sb_block);
735 		if(!bh) {
736 			printk("EXT2-fs: Couldn't read superblock on "
737 			       "2nd try.\n");
738 			goto failed_sbi;
739 		}
740 		es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
741 		sbi->s_es = es;
742 		if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
743 			printk ("EXT2-fs: Magic mismatch, very weird !\n");
744 			goto failed_mount;
745 		}
746 	}
747 
748 	sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
749 
750 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
751 		sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
752 		sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
753 	} else {
754 		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
755 		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
756 		if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
757 		    (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
758 		    (sbi->s_inode_size > blocksize)) {
759 			printk ("EXT2-fs: unsupported inode size: %d\n",
760 				sbi->s_inode_size);
761 			goto failed_mount;
762 		}
763 	}
764 
765 	sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
766 				   le32_to_cpu(es->s_log_frag_size);
767 	if (sbi->s_frag_size == 0)
768 		goto cantfind_ext2;
769 	sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
770 
771 	sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
772 	sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
773 	sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
774 
775 	if (EXT2_INODE_SIZE(sb) == 0)
776 		goto cantfind_ext2;
777 	sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
778 	if (sbi->s_inodes_per_block == 0)
779 		goto cantfind_ext2;
780 	sbi->s_itb_per_group = sbi->s_inodes_per_group /
781 					sbi->s_inodes_per_block;
782 	sbi->s_desc_per_block = sb->s_blocksize /
783 					sizeof (struct ext2_group_desc);
784 	sbi->s_sbh = bh;
785 	sbi->s_mount_state = le16_to_cpu(es->s_state);
786 	sbi->s_addr_per_block_bits =
787 		log2 (EXT2_ADDR_PER_BLOCK(sb));
788 	sbi->s_desc_per_block_bits =
789 		log2 (EXT2_DESC_PER_BLOCK(sb));
790 
791 	if (sb->s_magic != EXT2_SUPER_MAGIC)
792 		goto cantfind_ext2;
793 
794 	if (sb->s_blocksize != bh->b_size) {
795 		if (!silent)
796 			printk ("VFS: Unsupported blocksize on dev "
797 				"%s.\n", sb->s_id);
798 		goto failed_mount;
799 	}
800 
801 	if (sb->s_blocksize != sbi->s_frag_size) {
802 		printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
803 			sbi->s_frag_size, sb->s_blocksize);
804 		goto failed_mount;
805 	}
806 
807 	if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
808 		printk ("EXT2-fs: #blocks per group too big: %lu\n",
809 			sbi->s_blocks_per_group);
810 		goto failed_mount;
811 	}
812 	if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
813 		printk ("EXT2-fs: #fragments per group too big: %lu\n",
814 			sbi->s_frags_per_group);
815 		goto failed_mount;
816 	}
817 	if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
818 		printk ("EXT2-fs: #inodes per group too big: %lu\n",
819 			sbi->s_inodes_per_group);
820 		goto failed_mount;
821 	}
822 
823 	if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
824 		goto cantfind_ext2;
825 	sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
826 				        le32_to_cpu(es->s_first_data_block) +
827 				       EXT2_BLOCKS_PER_GROUP(sb) - 1) /
828 				       EXT2_BLOCKS_PER_GROUP(sb);
829 	db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
830 		   EXT2_DESC_PER_BLOCK(sb);
831 	sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
832 	if (sbi->s_group_desc == NULL) {
833 		printk ("EXT2-fs: not enough memory\n");
834 		goto failed_mount;
835 	}
836 	bgl_lock_init(&sbi->s_blockgroup_lock);
837 	sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
838 			       GFP_KERNEL);
839 	if (!sbi->s_debts) {
840 		printk ("EXT2-fs: not enough memory\n");
841 		goto failed_mount_group_desc;
842 	}
843 	memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
844 	for (i = 0; i < db_count; i++) {
845 		block = descriptor_loc(sb, logic_sb_block, i);
846 		sbi->s_group_desc[i] = sb_bread(sb, block);
847 		if (!sbi->s_group_desc[i]) {
848 			for (j = 0; j < i; j++)
849 				brelse (sbi->s_group_desc[j]);
850 			printk ("EXT2-fs: unable to read group descriptors\n");
851 			goto failed_mount_group_desc;
852 		}
853 	}
854 	if (!ext2_check_descriptors (sb)) {
855 		printk ("EXT2-fs: group descriptors corrupted!\n");
856 		goto failed_mount2;
857 	}
858 	sbi->s_gdb_count = db_count;
859 	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
860 	spin_lock_init(&sbi->s_next_gen_lock);
861 
862 	percpu_counter_init(&sbi->s_freeblocks_counter,
863 				ext2_count_free_blocks(sb));
864 	percpu_counter_init(&sbi->s_freeinodes_counter,
865 				ext2_count_free_inodes(sb));
866 	percpu_counter_init(&sbi->s_dirs_counter,
867 				ext2_count_dirs(sb));
868 	/*
869 	 * set up enough so that it can read an inode
870 	 */
871 	sb->s_op = &ext2_sops;
872 	sb->s_export_op = &ext2_export_ops;
873 	sb->s_xattr = ext2_xattr_handlers;
874 	root = iget(sb, EXT2_ROOT_INO);
875 	sb->s_root = d_alloc_root(root);
876 	if (!sb->s_root) {
877 		iput(root);
878 		printk(KERN_ERR "EXT2-fs: get root inode failed\n");
879 		goto failed_mount3;
880 	}
881 	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
882 		dput(sb->s_root);
883 		sb->s_root = NULL;
884 		printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
885 		goto failed_mount3;
886 	}
887 	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
888 		ext2_warning(sb, __FUNCTION__,
889 			"mounting ext3 filesystem as ext2");
890 	ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
891 	return 0;
892 
893 cantfind_ext2:
894 	if (!silent)
895 		printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
896 		       sb->s_id);
897 	goto failed_mount;
898 failed_mount3:
899 	percpu_counter_destroy(&sbi->s_freeblocks_counter);
900 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
901 	percpu_counter_destroy(&sbi->s_dirs_counter);
902 failed_mount2:
903 	for (i = 0; i < db_count; i++)
904 		brelse(sbi->s_group_desc[i]);
905 failed_mount_group_desc:
906 	kfree(sbi->s_group_desc);
907 	kfree(sbi->s_debts);
908 failed_mount:
909 	brelse(bh);
910 failed_sbi:
911 	sb->s_fs_info = NULL;
912 	kfree(sbi);
913 	return -EINVAL;
914 }
915 
916 static void ext2_commit_super (struct super_block * sb,
917 			       struct ext2_super_block * es)
918 {
919 	es->s_wtime = cpu_to_le32(get_seconds());
920 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
921 	sb->s_dirt = 0;
922 }
923 
924 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
925 {
926 	es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
927 	es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
928 	es->s_wtime = cpu_to_le32(get_seconds());
929 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
930 	sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
931 	sb->s_dirt = 0;
932 }
933 
934 /*
935  * In the second extended file system, it is not necessary to
936  * write the super block since we use a mapping of the
937  * disk super block in a buffer.
938  *
939  * However, this function is still used to set the fs valid
940  * flags to 0.  We need to set this flag to 0 since the fs
941  * may have been checked while mounted and e2fsck may have
942  * set s_state to EXT2_VALID_FS after some corrections.
943  */
944 
945 void ext2_write_super (struct super_block * sb)
946 {
947 	struct ext2_super_block * es;
948 	lock_kernel();
949 	if (!(sb->s_flags & MS_RDONLY)) {
950 		es = EXT2_SB(sb)->s_es;
951 
952 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
953 			ext2_debug ("setting valid to 0\n");
954 			es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
955 						  ~EXT2_VALID_FS);
956 			es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
957 			es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
958 			es->s_mtime = cpu_to_le32(get_seconds());
959 			ext2_sync_super(sb, es);
960 		} else
961 			ext2_commit_super (sb, es);
962 	}
963 	sb->s_dirt = 0;
964 	unlock_kernel();
965 }
966 
967 static int ext2_remount (struct super_block * sb, int * flags, char * data)
968 {
969 	struct ext2_sb_info * sbi = EXT2_SB(sb);
970 	struct ext2_super_block * es;
971 	unsigned long old_mount_opt = sbi->s_mount_opt;
972 	struct ext2_mount_options old_opts;
973 	unsigned long old_sb_flags;
974 	int err;
975 
976 	/* Store the old options */
977 	old_sb_flags = sb->s_flags;
978 	old_opts.s_mount_opt = sbi->s_mount_opt;
979 	old_opts.s_resuid = sbi->s_resuid;
980 	old_opts.s_resgid = sbi->s_resgid;
981 
982 	/*
983 	 * Allow the "check" option to be passed as a remount option.
984 	 */
985 	if (!parse_options (data, sbi)) {
986 		err = -EINVAL;
987 		goto restore_opts;
988 	}
989 
990 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
991 		((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
992 
993 	es = sbi->s_es;
994 	if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
995 	    (old_mount_opt & EXT2_MOUNT_XIP)) &&
996 	    invalidate_inodes(sb))
997 		ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
998 			     "xip remain in cache (no functional problem)");
999 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1000 		return 0;
1001 	if (*flags & MS_RDONLY) {
1002 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1003 		    !(sbi->s_mount_state & EXT2_VALID_FS))
1004 			return 0;
1005 		/*
1006 		 * OK, we are remounting a valid rw partition rdonly, so set
1007 		 * the rdonly flag and then mark the partition as valid again.
1008 		 */
1009 		es->s_state = cpu_to_le16(sbi->s_mount_state);
1010 		es->s_mtime = cpu_to_le32(get_seconds());
1011 	} else {
1012 		__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1013 					       ~EXT2_FEATURE_RO_COMPAT_SUPP);
1014 		if (ret) {
1015 			printk("EXT2-fs: %s: couldn't remount RDWR because of "
1016 			       "unsupported optional features (%x).\n",
1017 			       sb->s_id, le32_to_cpu(ret));
1018 			err = -EROFS;
1019 			goto restore_opts;
1020 		}
1021 		/*
1022 		 * Mounting a RDONLY partition read-write, so reread and
1023 		 * store the current valid flag.  (It may have been changed
1024 		 * by e2fsck since we originally mounted the partition.)
1025 		 */
1026 		sbi->s_mount_state = le16_to_cpu(es->s_state);
1027 		if (!ext2_setup_super (sb, es, 0))
1028 			sb->s_flags &= ~MS_RDONLY;
1029 	}
1030 	ext2_sync_super(sb, es);
1031 	return 0;
1032 restore_opts:
1033 	sbi->s_mount_opt = old_opts.s_mount_opt;
1034 	sbi->s_resuid = old_opts.s_resuid;
1035 	sbi->s_resgid = old_opts.s_resgid;
1036 	sb->s_flags = old_sb_flags;
1037 	return err;
1038 }
1039 
1040 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1041 {
1042 	struct super_block *sb = dentry->d_sb;
1043 	struct ext2_sb_info *sbi = EXT2_SB(sb);
1044 	unsigned long overhead;
1045 	int i;
1046 
1047 	lock_super(sb);
1048 	if (test_opt (sb, MINIX_DF))
1049 		overhead = 0;
1050 	else {
1051 		/*
1052 		 * Compute the overhead (FS structures)
1053 		 */
1054 
1055 		/*
1056 		 * All of the blocks before first_data_block are
1057 		 * overhead
1058 		 */
1059 		overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
1060 
1061 		/*
1062 		 * Add the overhead attributed to the superblock and
1063 		 * block group descriptors.  If the sparse superblocks
1064 		 * feature is turned on, then not all groups have this.
1065 		 */
1066 		for (i = 0; i < sbi->s_groups_count; i++)
1067 			overhead += ext2_bg_has_super(sb, i) +
1068 				ext2_bg_num_gdb(sb, i);
1069 
1070 		/*
1071 		 * Every block group has an inode bitmap, a block
1072 		 * bitmap, and an inode table.
1073 		 */
1074 		overhead += (sbi->s_groups_count *
1075 			     (2 + sbi->s_itb_per_group));
1076 	}
1077 
1078 	buf->f_type = EXT2_SUPER_MAGIC;
1079 	buf->f_bsize = sb->s_blocksize;
1080 	buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
1081 	buf->f_bfree = ext2_count_free_blocks(sb);
1082 	buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1083 	if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1084 		buf->f_bavail = 0;
1085 	buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1086 	buf->f_ffree = ext2_count_free_inodes (sb);
1087 	buf->f_namelen = EXT2_NAME_LEN;
1088 	unlock_super(sb);
1089 	return 0;
1090 }
1091 
1092 static int ext2_get_sb(struct file_system_type *fs_type,
1093 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1094 {
1095 	return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1096 }
1097 
1098 #ifdef CONFIG_QUOTA
1099 
1100 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1101  * acquiring the locks... As quota files are never truncated and quota code
1102  * itself serializes the operations (and noone else should touch the files)
1103  * we don't have to be afraid of races */
1104 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1105 			       size_t len, loff_t off)
1106 {
1107 	struct inode *inode = sb_dqopt(sb)->files[type];
1108 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1109 	int err = 0;
1110 	int offset = off & (sb->s_blocksize - 1);
1111 	int tocopy;
1112 	size_t toread;
1113 	struct buffer_head tmp_bh;
1114 	struct buffer_head *bh;
1115 	loff_t i_size = i_size_read(inode);
1116 
1117 	if (off > i_size)
1118 		return 0;
1119 	if (off+len > i_size)
1120 		len = i_size-off;
1121 	toread = len;
1122 	while (toread > 0) {
1123 		tocopy = sb->s_blocksize - offset < toread ?
1124 				sb->s_blocksize - offset : toread;
1125 
1126 		tmp_bh.b_state = 0;
1127 		err = ext2_get_block(inode, blk, &tmp_bh, 0);
1128 		if (err)
1129 			return err;
1130 		if (!buffer_mapped(&tmp_bh))	/* A hole? */
1131 			memset(data, 0, tocopy);
1132 		else {
1133 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1134 			if (!bh)
1135 				return -EIO;
1136 			memcpy(data, bh->b_data+offset, tocopy);
1137 			brelse(bh);
1138 		}
1139 		offset = 0;
1140 		toread -= tocopy;
1141 		data += tocopy;
1142 		blk++;
1143 	}
1144 	return len;
1145 }
1146 
1147 /* Write to quotafile */
1148 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1149 				const char *data, size_t len, loff_t off)
1150 {
1151 	struct inode *inode = sb_dqopt(sb)->files[type];
1152 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1153 	int err = 0;
1154 	int offset = off & (sb->s_blocksize - 1);
1155 	int tocopy;
1156 	size_t towrite = len;
1157 	struct buffer_head tmp_bh;
1158 	struct buffer_head *bh;
1159 
1160 	mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1161 	while (towrite > 0) {
1162 		tocopy = sb->s_blocksize - offset < towrite ?
1163 				sb->s_blocksize - offset : towrite;
1164 
1165 		tmp_bh.b_state = 0;
1166 		err = ext2_get_block(inode, blk, &tmp_bh, 1);
1167 		if (err)
1168 			goto out;
1169 		if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1170 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1171 		else
1172 			bh = sb_getblk(sb, tmp_bh.b_blocknr);
1173 		if (!bh) {
1174 			err = -EIO;
1175 			goto out;
1176 		}
1177 		lock_buffer(bh);
1178 		memcpy(bh->b_data+offset, data, tocopy);
1179 		flush_dcache_page(bh->b_page);
1180 		set_buffer_uptodate(bh);
1181 		mark_buffer_dirty(bh);
1182 		unlock_buffer(bh);
1183 		brelse(bh);
1184 		offset = 0;
1185 		towrite -= tocopy;
1186 		data += tocopy;
1187 		blk++;
1188 	}
1189 out:
1190 	if (len == towrite)
1191 		return err;
1192 	if (inode->i_size < off+len-towrite)
1193 		i_size_write(inode, off+len-towrite);
1194 	inode->i_version++;
1195 	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1196 	mark_inode_dirty(inode);
1197 	mutex_unlock(&inode->i_mutex);
1198 	return len - towrite;
1199 }
1200 
1201 #endif
1202 
1203 static struct file_system_type ext2_fs_type = {
1204 	.owner		= THIS_MODULE,
1205 	.name		= "ext2",
1206 	.get_sb		= ext2_get_sb,
1207 	.kill_sb	= kill_block_super,
1208 	.fs_flags	= FS_REQUIRES_DEV,
1209 };
1210 
1211 static int __init init_ext2_fs(void)
1212 {
1213 	int err = init_ext2_xattr();
1214 	if (err)
1215 		return err;
1216 	err = init_inodecache();
1217 	if (err)
1218 		goto out1;
1219         err = register_filesystem(&ext2_fs_type);
1220 	if (err)
1221 		goto out;
1222 	return 0;
1223 out:
1224 	destroy_inodecache();
1225 out1:
1226 	exit_ext2_xattr();
1227 	return err;
1228 }
1229 
1230 static void __exit exit_ext2_fs(void)
1231 {
1232 	unregister_filesystem(&ext2_fs_type);
1233 	destroy_inodecache();
1234 	exit_ext2_xattr();
1235 }
1236 
1237 module_init(init_ext2_fs)
1238 module_exit(exit_ext2_fs)
1239