xref: /linux/fs/ext2/super.c (revision 606d099cdd1080bbb50ea50dc52d98252f8f10a1)
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_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 	kmem_cache_destroy(ext2_inode_cachep);
188 }
189 
190 static void ext2_clear_inode(struct inode *inode)
191 {
192 #ifdef CONFIG_EXT2_FS_POSIX_ACL
193 	struct ext2_inode_info *ei = EXT2_I(inode);
194 
195 	if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
196 		posix_acl_release(ei->i_acl);
197 		ei->i_acl = EXT2_ACL_NOT_CACHED;
198 	}
199 	if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
200 		posix_acl_release(ei->i_default_acl);
201 		ei->i_default_acl = EXT2_ACL_NOT_CACHED;
202 	}
203 #endif
204 }
205 
206 static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
207 {
208 	struct ext2_sb_info *sbi = EXT2_SB(vfs->mnt_sb);
209 
210 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPID)
211 		seq_puts(seq, ",grpid");
212 
213 #if defined(CONFIG_QUOTA)
214 	if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
215 		seq_puts(seq, ",usrquota");
216 
217 	if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
218 		seq_puts(seq, ",grpquota");
219 #endif
220 
221 #if defined(CONFIG_EXT2_FS_XIP)
222 	if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
223 		seq_puts(seq, ",xip");
224 #endif
225 
226 	return 0;
227 }
228 
229 #ifdef CONFIG_QUOTA
230 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
231 static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
232 #endif
233 
234 static struct super_operations ext2_sops = {
235 	.alloc_inode	= ext2_alloc_inode,
236 	.destroy_inode	= ext2_destroy_inode,
237 	.read_inode	= ext2_read_inode,
238 	.write_inode	= ext2_write_inode,
239 	.put_inode	= ext2_put_inode,
240 	.delete_inode	= ext2_delete_inode,
241 	.put_super	= ext2_put_super,
242 	.write_super	= ext2_write_super,
243 	.statfs		= ext2_statfs,
244 	.remount_fs	= ext2_remount,
245 	.clear_inode	= ext2_clear_inode,
246 	.show_options	= ext2_show_options,
247 #ifdef CONFIG_QUOTA
248 	.quota_read	= ext2_quota_read,
249 	.quota_write	= ext2_quota_write,
250 #endif
251 };
252 
253 static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
254 {
255 	__u32 *objp = vobjp;
256 	unsigned long ino = objp[0];
257 	__u32 generation = objp[1];
258 	struct inode *inode;
259 	struct dentry *result;
260 
261 	if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
262 		return ERR_PTR(-ESTALE);
263 	if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
264 		return ERR_PTR(-ESTALE);
265 
266 	/* iget isn't really right if the inode is currently unallocated!!
267 	 * ext2_read_inode currently does appropriate checks, but
268 	 * it might be "neater" to call ext2_get_inode first and check
269 	 * if the inode is valid.....
270 	 */
271 	inode = iget(sb, ino);
272 	if (inode == NULL)
273 		return ERR_PTR(-ENOMEM);
274 	if (is_bad_inode(inode) ||
275 	    (generation && inode->i_generation != generation)) {
276 		/* we didn't find the right inode.. */
277 		iput(inode);
278 		return ERR_PTR(-ESTALE);
279 	}
280 	/* now to find a dentry.
281 	 * If possible, get a well-connected one
282 	 */
283 	result = d_alloc_anon(inode);
284 	if (!result) {
285 		iput(inode);
286 		return ERR_PTR(-ENOMEM);
287 	}
288 	return result;
289 }
290 
291 /* Yes, most of these are left as NULL!!
292  * A NULL value implies the default, which works with ext2-like file
293  * systems, but can be improved upon.
294  * Currently only get_parent is required.
295  */
296 static struct export_operations ext2_export_ops = {
297 	.get_parent = ext2_get_parent,
298 	.get_dentry = ext2_get_dentry,
299 };
300 
301 static unsigned long get_sb_block(void **data)
302 {
303 	unsigned long 	sb_block;
304 	char 		*options = (char *) *data;
305 
306 	if (!options || strncmp(options, "sb=", 3) != 0)
307 		return 1;	/* Default location */
308 	options += 3;
309 	sb_block = simple_strtoul(options, &options, 0);
310 	if (*options && *options != ',') {
311 		printk("EXT2-fs: Invalid sb specification: %s\n",
312 		       (char *) *data);
313 		return 1;
314 	}
315 	if (*options == ',')
316 		options++;
317 	*data = (void *) options;
318 	return sb_block;
319 }
320 
321 enum {
322 	Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
323 	Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
324 	Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
325 	Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
326 	Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
327 	Opt_usrquota, Opt_grpquota
328 };
329 
330 static match_table_t tokens = {
331 	{Opt_bsd_df, "bsddf"},
332 	{Opt_minix_df, "minixdf"},
333 	{Opt_grpid, "grpid"},
334 	{Opt_grpid, "bsdgroups"},
335 	{Opt_nogrpid, "nogrpid"},
336 	{Opt_nogrpid, "sysvgroups"},
337 	{Opt_resgid, "resgid=%u"},
338 	{Opt_resuid, "resuid=%u"},
339 	{Opt_sb, "sb=%u"},
340 	{Opt_err_cont, "errors=continue"},
341 	{Opt_err_panic, "errors=panic"},
342 	{Opt_err_ro, "errors=remount-ro"},
343 	{Opt_nouid32, "nouid32"},
344 	{Opt_nocheck, "check=none"},
345 	{Opt_nocheck, "nocheck"},
346 	{Opt_debug, "debug"},
347 	{Opt_oldalloc, "oldalloc"},
348 	{Opt_orlov, "orlov"},
349 	{Opt_nobh, "nobh"},
350 	{Opt_user_xattr, "user_xattr"},
351 	{Opt_nouser_xattr, "nouser_xattr"},
352 	{Opt_acl, "acl"},
353 	{Opt_noacl, "noacl"},
354 	{Opt_xip, "xip"},
355 	{Opt_grpquota, "grpquota"},
356 	{Opt_ignore, "noquota"},
357 	{Opt_quota, "quota"},
358 	{Opt_usrquota, "usrquota"},
359 	{Opt_err, NULL}
360 };
361 
362 static int parse_options (char * options,
363 			  struct ext2_sb_info *sbi)
364 {
365 	char * p;
366 	substring_t args[MAX_OPT_ARGS];
367 	int option;
368 
369 	if (!options)
370 		return 1;
371 
372 	while ((p = strsep (&options, ",")) != NULL) {
373 		int token;
374 		if (!*p)
375 			continue;
376 
377 		token = match_token(p, tokens, args);
378 		switch (token) {
379 		case Opt_bsd_df:
380 			clear_opt (sbi->s_mount_opt, MINIX_DF);
381 			break;
382 		case Opt_minix_df:
383 			set_opt (sbi->s_mount_opt, MINIX_DF);
384 			break;
385 		case Opt_grpid:
386 			set_opt (sbi->s_mount_opt, GRPID);
387 			break;
388 		case Opt_nogrpid:
389 			clear_opt (sbi->s_mount_opt, GRPID);
390 			break;
391 		case Opt_resuid:
392 			if (match_int(&args[0], &option))
393 				return 0;
394 			sbi->s_resuid = option;
395 			break;
396 		case Opt_resgid:
397 			if (match_int(&args[0], &option))
398 				return 0;
399 			sbi->s_resgid = option;
400 			break;
401 		case Opt_sb:
402 			/* handled by get_sb_block() instead of here */
403 			/* *sb_block = match_int(&args[0]); */
404 			break;
405 		case Opt_err_panic:
406 			clear_opt (sbi->s_mount_opt, ERRORS_CONT);
407 			clear_opt (sbi->s_mount_opt, ERRORS_RO);
408 			set_opt (sbi->s_mount_opt, ERRORS_PANIC);
409 			break;
410 		case Opt_err_ro:
411 			clear_opt (sbi->s_mount_opt, ERRORS_CONT);
412 			clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
413 			set_opt (sbi->s_mount_opt, ERRORS_RO);
414 			break;
415 		case Opt_err_cont:
416 			clear_opt (sbi->s_mount_opt, ERRORS_RO);
417 			clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
418 			set_opt (sbi->s_mount_opt, ERRORS_CONT);
419 			break;
420 		case Opt_nouid32:
421 			set_opt (sbi->s_mount_opt, NO_UID32);
422 			break;
423 		case Opt_nocheck:
424 			clear_opt (sbi->s_mount_opt, CHECK);
425 			break;
426 		case Opt_debug:
427 			set_opt (sbi->s_mount_opt, DEBUG);
428 			break;
429 		case Opt_oldalloc:
430 			set_opt (sbi->s_mount_opt, OLDALLOC);
431 			break;
432 		case Opt_orlov:
433 			clear_opt (sbi->s_mount_opt, OLDALLOC);
434 			break;
435 		case Opt_nobh:
436 			set_opt (sbi->s_mount_opt, NOBH);
437 			break;
438 #ifdef CONFIG_EXT2_FS_XATTR
439 		case Opt_user_xattr:
440 			set_opt (sbi->s_mount_opt, XATTR_USER);
441 			break;
442 		case Opt_nouser_xattr:
443 			clear_opt (sbi->s_mount_opt, XATTR_USER);
444 			break;
445 #else
446 		case Opt_user_xattr:
447 		case Opt_nouser_xattr:
448 			printk("EXT2 (no)user_xattr options not supported\n");
449 			break;
450 #endif
451 #ifdef CONFIG_EXT2_FS_POSIX_ACL
452 		case Opt_acl:
453 			set_opt(sbi->s_mount_opt, POSIX_ACL);
454 			break;
455 		case Opt_noacl:
456 			clear_opt(sbi->s_mount_opt, POSIX_ACL);
457 			break;
458 #else
459 		case Opt_acl:
460 		case Opt_noacl:
461 			printk("EXT2 (no)acl options not supported\n");
462 			break;
463 #endif
464 		case Opt_xip:
465 #ifdef CONFIG_EXT2_FS_XIP
466 			set_opt (sbi->s_mount_opt, XIP);
467 #else
468 			printk("EXT2 xip option not supported\n");
469 #endif
470 			break;
471 
472 #if defined(CONFIG_QUOTA)
473 		case Opt_quota:
474 		case Opt_usrquota:
475 			set_opt(sbi->s_mount_opt, USRQUOTA);
476 			break;
477 
478 		case Opt_grpquota:
479 			set_opt(sbi->s_mount_opt, GRPQUOTA);
480 			break;
481 #else
482 		case Opt_quota:
483 		case Opt_usrquota:
484 		case Opt_grpquota:
485 			printk(KERN_ERR
486 				"EXT2-fs: quota operations not supported.\n");
487 
488 			break;
489 #endif
490 
491 		case Opt_ignore:
492 			break;
493 		default:
494 			return 0;
495 		}
496 	}
497 	return 1;
498 }
499 
500 static int ext2_setup_super (struct super_block * sb,
501 			      struct ext2_super_block * es,
502 			      int read_only)
503 {
504 	int res = 0;
505 	struct ext2_sb_info *sbi = EXT2_SB(sb);
506 
507 	if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
508 		printk ("EXT2-fs warning: revision level too high, "
509 			"forcing read-only mode\n");
510 		res = MS_RDONLY;
511 	}
512 	if (read_only)
513 		return res;
514 	if (!(sbi->s_mount_state & EXT2_VALID_FS))
515 		printk ("EXT2-fs warning: mounting unchecked fs, "
516 			"running e2fsck is recommended\n");
517 	else if ((sbi->s_mount_state & EXT2_ERROR_FS))
518 		printk ("EXT2-fs warning: mounting fs with errors, "
519 			"running e2fsck is recommended\n");
520 	else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
521 		 le16_to_cpu(es->s_mnt_count) >=
522 		 (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
523 		printk ("EXT2-fs warning: maximal mount count reached, "
524 			"running e2fsck is recommended\n");
525 	else if (le32_to_cpu(es->s_checkinterval) &&
526 		(le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
527 		printk ("EXT2-fs warning: checktime reached, "
528 			"running e2fsck is recommended\n");
529 	if (!le16_to_cpu(es->s_max_mnt_count))
530 		es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
531 	es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
532 	ext2_write_super(sb);
533 	if (test_opt (sb, DEBUG))
534 		printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
535 			"bpg=%lu, ipg=%lu, mo=%04lx]\n",
536 			EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
537 			sbi->s_frag_size,
538 			sbi->s_groups_count,
539 			EXT2_BLOCKS_PER_GROUP(sb),
540 			EXT2_INODES_PER_GROUP(sb),
541 			sbi->s_mount_opt);
542 	return res;
543 }
544 
545 static int ext2_check_descriptors (struct super_block * sb)
546 {
547 	int i;
548 	int desc_block = 0;
549 	struct ext2_sb_info *sbi = EXT2_SB(sb);
550 	unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
551 	unsigned long last_block;
552 	struct ext2_group_desc * gdp = NULL;
553 
554 	ext2_debug ("Checking group descriptors");
555 
556 	for (i = 0; i < sbi->s_groups_count; i++)
557 	{
558 		if (i == sbi->s_groups_count - 1)
559 			last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
560 		else
561 			last_block = first_block +
562 				(EXT2_BLOCKS_PER_GROUP(sb) - 1);
563 
564 		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
565 			gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
566 		if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
567 		    le32_to_cpu(gdp->bg_block_bitmap) > last_block)
568 		{
569 			ext2_error (sb, "ext2_check_descriptors",
570 				    "Block bitmap for group %d"
571 				    " not in group (block %lu)!",
572 				    i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
573 			return 0;
574 		}
575 		if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
576 		    le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
577 		{
578 			ext2_error (sb, "ext2_check_descriptors",
579 				    "Inode bitmap for group %d"
580 				    " not in group (block %lu)!",
581 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
582 			return 0;
583 		}
584 		if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
585 		    le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >
586 		    last_block)
587 		{
588 			ext2_error (sb, "ext2_check_descriptors",
589 				    "Inode table for group %d"
590 				    " not in group (block %lu)!",
591 				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
592 			return 0;
593 		}
594 		first_block += EXT2_BLOCKS_PER_GROUP(sb);
595 		gdp++;
596 	}
597 	return 1;
598 }
599 
600 /*
601  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
602  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
603  * We need to be 1 filesystem block less than the 2^32 sector limit.
604  */
605 static loff_t ext2_max_size(int bits)
606 {
607 	loff_t res = EXT2_NDIR_BLOCKS;
608 	/* This constant is calculated to be the largest file size for a
609 	 * dense, 4k-blocksize file such that the total number of
610 	 * sectors in the file, including data and all indirect blocks,
611 	 * does not exceed 2^32. */
612 	const loff_t upper_limit = 0x1ff7fffd000LL;
613 
614 	res += 1LL << (bits-2);
615 	res += 1LL << (2*(bits-2));
616 	res += 1LL << (3*(bits-2));
617 	res <<= bits;
618 	if (res > upper_limit)
619 		res = upper_limit;
620 	return res;
621 }
622 
623 static unsigned long descriptor_loc(struct super_block *sb,
624 				    unsigned long logic_sb_block,
625 				    int nr)
626 {
627 	struct ext2_sb_info *sbi = EXT2_SB(sb);
628 	unsigned long bg, first_data_block, first_meta_bg;
629 	int has_super = 0;
630 
631 	first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
632 	first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
633 
634 	if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
635 	    nr < first_meta_bg)
636 		return (logic_sb_block + nr + 1);
637 	bg = sbi->s_desc_per_block * nr;
638 	if (ext2_bg_has_super(sb, bg))
639 		has_super = 1;
640 	return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
641 }
642 
643 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
644 {
645 	struct buffer_head * bh;
646 	struct ext2_sb_info * sbi;
647 	struct ext2_super_block * es;
648 	struct inode *root;
649 	unsigned long block;
650 	unsigned long sb_block = get_sb_block(&data);
651 	unsigned long logic_sb_block;
652 	unsigned long offset = 0;
653 	unsigned long def_mount_opts;
654 	int blocksize = BLOCK_SIZE;
655 	int db_count;
656 	int i, j;
657 	__le32 features;
658 
659 	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
660 	if (!sbi)
661 		return -ENOMEM;
662 	sb->s_fs_info = sbi;
663 
664 	/*
665 	 * See what the current blocksize for the device is, and
666 	 * use that as the blocksize.  Otherwise (or if the blocksize
667 	 * is smaller than the default) use the default.
668 	 * This is important for devices that have a hardware
669 	 * sectorsize that is larger than the default.
670 	 */
671 	blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
672 	if (!blocksize) {
673 		printk ("EXT2-fs: unable to set blocksize\n");
674 		goto failed_sbi;
675 	}
676 
677 	/*
678 	 * If the superblock doesn't start on a hardware sector boundary,
679 	 * calculate the offset.
680 	 */
681 	if (blocksize != BLOCK_SIZE) {
682 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
683 		offset = (sb_block*BLOCK_SIZE) % blocksize;
684 	} else {
685 		logic_sb_block = sb_block;
686 	}
687 
688 	if (!(bh = sb_bread(sb, logic_sb_block))) {
689 		printk ("EXT2-fs: unable to read superblock\n");
690 		goto failed_sbi;
691 	}
692 	/*
693 	 * Note: s_es must be initialized as soon as possible because
694 	 *       some ext2 macro-instructions depend on its value
695 	 */
696 	es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
697 	sbi->s_es = es;
698 	sb->s_magic = le16_to_cpu(es->s_magic);
699 
700 	if (sb->s_magic != EXT2_SUPER_MAGIC)
701 		goto cantfind_ext2;
702 
703 	/* Set defaults before we parse the mount options */
704 	def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
705 	if (def_mount_opts & EXT2_DEFM_DEBUG)
706 		set_opt(sbi->s_mount_opt, DEBUG);
707 	if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
708 		set_opt(sbi->s_mount_opt, GRPID);
709 	if (def_mount_opts & EXT2_DEFM_UID16)
710 		set_opt(sbi->s_mount_opt, NO_UID32);
711 	if (def_mount_opts & EXT2_DEFM_XATTR_USER)
712 		set_opt(sbi->s_mount_opt, XATTR_USER);
713 	if (def_mount_opts & EXT2_DEFM_ACL)
714 		set_opt(sbi->s_mount_opt, POSIX_ACL);
715 
716 	if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
717 		set_opt(sbi->s_mount_opt, ERRORS_PANIC);
718 	else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
719 		set_opt(sbi->s_mount_opt, ERRORS_RO);
720 	else
721 		set_opt(sbi->s_mount_opt, ERRORS_CONT);
722 
723 	sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
724 	sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
725 
726 	if (!parse_options ((char *) data, sbi))
727 		goto failed_mount;
728 
729 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
730 		((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
731 		 MS_POSIXACL : 0);
732 
733 	ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
734 				    EXT2_MOUNT_XIP if not */
735 
736 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
737 	    (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
738 	     EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
739 	     EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
740 		printk("EXT2-fs warning: feature flags set on rev 0 fs, "
741 		       "running e2fsck is recommended\n");
742 	/*
743 	 * Check feature flags regardless of the revision level, since we
744 	 * previously didn't change the revision level when setting the flags,
745 	 * so there is a chance incompat flags are set on a rev 0 filesystem.
746 	 */
747 	features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
748 	if (features) {
749 		printk("EXT2-fs: %s: couldn't mount because of "
750 		       "unsupported optional features (%x).\n",
751 		       sb->s_id, le32_to_cpu(features));
752 		goto failed_mount;
753 	}
754 	if (!(sb->s_flags & MS_RDONLY) &&
755 	    (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
756 		printk("EXT2-fs: %s: couldn't mount RDWR because of "
757 		       "unsupported optional features (%x).\n",
758 		       sb->s_id, le32_to_cpu(features));
759 		goto failed_mount;
760 	}
761 
762 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
763 
764 	if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
765 				  (sb->s_blocksize != blocksize))) {
766 		if (!silent)
767 			printk("XIP: Unsupported blocksize\n");
768 		goto failed_mount;
769 	}
770 
771 	/* If the blocksize doesn't match, re-read the thing.. */
772 	if (sb->s_blocksize != blocksize) {
773 		brelse(bh);
774 
775 		if (!sb_set_blocksize(sb, blocksize)) {
776 			printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
777 			goto failed_sbi;
778 		}
779 
780 		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
781 		offset = (sb_block*BLOCK_SIZE) % blocksize;
782 		bh = sb_bread(sb, logic_sb_block);
783 		if(!bh) {
784 			printk("EXT2-fs: Couldn't read superblock on "
785 			       "2nd try.\n");
786 			goto failed_sbi;
787 		}
788 		es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
789 		sbi->s_es = es;
790 		if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
791 			printk ("EXT2-fs: Magic mismatch, very weird !\n");
792 			goto failed_mount;
793 		}
794 	}
795 
796 	sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
797 
798 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
799 		sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
800 		sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
801 	} else {
802 		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
803 		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
804 		if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
805 		    (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
806 		    (sbi->s_inode_size > blocksize)) {
807 			printk ("EXT2-fs: unsupported inode size: %d\n",
808 				sbi->s_inode_size);
809 			goto failed_mount;
810 		}
811 	}
812 
813 	sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
814 				   le32_to_cpu(es->s_log_frag_size);
815 	if (sbi->s_frag_size == 0)
816 		goto cantfind_ext2;
817 	sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
818 
819 	sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
820 	sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
821 	sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
822 
823 	if (EXT2_INODE_SIZE(sb) == 0)
824 		goto cantfind_ext2;
825 	sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
826 	if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
827 		goto cantfind_ext2;
828 	sbi->s_itb_per_group = sbi->s_inodes_per_group /
829 					sbi->s_inodes_per_block;
830 	sbi->s_desc_per_block = sb->s_blocksize /
831 					sizeof (struct ext2_group_desc);
832 	sbi->s_sbh = bh;
833 	sbi->s_mount_state = le16_to_cpu(es->s_state);
834 	sbi->s_addr_per_block_bits =
835 		ilog2 (EXT2_ADDR_PER_BLOCK(sb));
836 	sbi->s_desc_per_block_bits =
837 		ilog2 (EXT2_DESC_PER_BLOCK(sb));
838 
839 	if (sb->s_magic != EXT2_SUPER_MAGIC)
840 		goto cantfind_ext2;
841 
842 	if (sb->s_blocksize != bh->b_size) {
843 		if (!silent)
844 			printk ("VFS: Unsupported blocksize on dev "
845 				"%s.\n", sb->s_id);
846 		goto failed_mount;
847 	}
848 
849 	if (sb->s_blocksize != sbi->s_frag_size) {
850 		printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
851 			sbi->s_frag_size, sb->s_blocksize);
852 		goto failed_mount;
853 	}
854 
855 	if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
856 		printk ("EXT2-fs: #blocks per group too big: %lu\n",
857 			sbi->s_blocks_per_group);
858 		goto failed_mount;
859 	}
860 	if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
861 		printk ("EXT2-fs: #fragments per group too big: %lu\n",
862 			sbi->s_frags_per_group);
863 		goto failed_mount;
864 	}
865 	if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
866 		printk ("EXT2-fs: #inodes per group too big: %lu\n",
867 			sbi->s_inodes_per_group);
868 		goto failed_mount;
869 	}
870 
871 	if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
872 		goto cantfind_ext2;
873  	sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
874  				le32_to_cpu(es->s_first_data_block) - 1)
875  					/ EXT2_BLOCKS_PER_GROUP(sb)) + 1;
876 	db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
877 		   EXT2_DESC_PER_BLOCK(sb);
878 	sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
879 	if (sbi->s_group_desc == NULL) {
880 		printk ("EXT2-fs: not enough memory\n");
881 		goto failed_mount;
882 	}
883 	bgl_lock_init(&sbi->s_blockgroup_lock);
884 	sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
885 			       GFP_KERNEL);
886 	if (!sbi->s_debts) {
887 		printk ("EXT2-fs: not enough memory\n");
888 		goto failed_mount_group_desc;
889 	}
890 	memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
891 	for (i = 0; i < db_count; i++) {
892 		block = descriptor_loc(sb, logic_sb_block, i);
893 		sbi->s_group_desc[i] = sb_bread(sb, block);
894 		if (!sbi->s_group_desc[i]) {
895 			for (j = 0; j < i; j++)
896 				brelse (sbi->s_group_desc[j]);
897 			printk ("EXT2-fs: unable to read group descriptors\n");
898 			goto failed_mount_group_desc;
899 		}
900 	}
901 	if (!ext2_check_descriptors (sb)) {
902 		printk ("EXT2-fs: group descriptors corrupted!\n");
903 		goto failed_mount2;
904 	}
905 	sbi->s_gdb_count = db_count;
906 	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
907 	spin_lock_init(&sbi->s_next_gen_lock);
908 
909 	percpu_counter_init(&sbi->s_freeblocks_counter,
910 				ext2_count_free_blocks(sb));
911 	percpu_counter_init(&sbi->s_freeinodes_counter,
912 				ext2_count_free_inodes(sb));
913 	percpu_counter_init(&sbi->s_dirs_counter,
914 				ext2_count_dirs(sb));
915 	/*
916 	 * set up enough so that it can read an inode
917 	 */
918 	sb->s_op = &ext2_sops;
919 	sb->s_export_op = &ext2_export_ops;
920 	sb->s_xattr = ext2_xattr_handlers;
921 	root = iget(sb, EXT2_ROOT_INO);
922 	sb->s_root = d_alloc_root(root);
923 	if (!sb->s_root) {
924 		iput(root);
925 		printk(KERN_ERR "EXT2-fs: get root inode failed\n");
926 		goto failed_mount3;
927 	}
928 	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
929 		dput(sb->s_root);
930 		sb->s_root = NULL;
931 		printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
932 		goto failed_mount3;
933 	}
934 	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
935 		ext2_warning(sb, __FUNCTION__,
936 			"mounting ext3 filesystem as ext2");
937 	ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
938 	return 0;
939 
940 cantfind_ext2:
941 	if (!silent)
942 		printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
943 		       sb->s_id);
944 	goto failed_mount;
945 failed_mount3:
946 	percpu_counter_destroy(&sbi->s_freeblocks_counter);
947 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
948 	percpu_counter_destroy(&sbi->s_dirs_counter);
949 failed_mount2:
950 	for (i = 0; i < db_count; i++)
951 		brelse(sbi->s_group_desc[i]);
952 failed_mount_group_desc:
953 	kfree(sbi->s_group_desc);
954 	kfree(sbi->s_debts);
955 failed_mount:
956 	brelse(bh);
957 failed_sbi:
958 	sb->s_fs_info = NULL;
959 	kfree(sbi);
960 	return -EINVAL;
961 }
962 
963 static void ext2_commit_super (struct super_block * sb,
964 			       struct ext2_super_block * es)
965 {
966 	es->s_wtime = cpu_to_le32(get_seconds());
967 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
968 	sb->s_dirt = 0;
969 }
970 
971 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
972 {
973 	es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
974 	es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
975 	es->s_wtime = cpu_to_le32(get_seconds());
976 	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
977 	sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
978 	sb->s_dirt = 0;
979 }
980 
981 /*
982  * In the second extended file system, it is not necessary to
983  * write the super block since we use a mapping of the
984  * disk super block in a buffer.
985  *
986  * However, this function is still used to set the fs valid
987  * flags to 0.  We need to set this flag to 0 since the fs
988  * may have been checked while mounted and e2fsck may have
989  * set s_state to EXT2_VALID_FS after some corrections.
990  */
991 
992 void ext2_write_super (struct super_block * sb)
993 {
994 	struct ext2_super_block * es;
995 	lock_kernel();
996 	if (!(sb->s_flags & MS_RDONLY)) {
997 		es = EXT2_SB(sb)->s_es;
998 
999 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
1000 			ext2_debug ("setting valid to 0\n");
1001 			es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
1002 						  ~EXT2_VALID_FS);
1003 			es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
1004 			es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
1005 			es->s_mtime = cpu_to_le32(get_seconds());
1006 			ext2_sync_super(sb, es);
1007 		} else
1008 			ext2_commit_super (sb, es);
1009 	}
1010 	sb->s_dirt = 0;
1011 	unlock_kernel();
1012 }
1013 
1014 static int ext2_remount (struct super_block * sb, int * flags, char * data)
1015 {
1016 	struct ext2_sb_info * sbi = EXT2_SB(sb);
1017 	struct ext2_super_block * es;
1018 	unsigned long old_mount_opt = sbi->s_mount_opt;
1019 	struct ext2_mount_options old_opts;
1020 	unsigned long old_sb_flags;
1021 	int err;
1022 
1023 	/* Store the old options */
1024 	old_sb_flags = sb->s_flags;
1025 	old_opts.s_mount_opt = sbi->s_mount_opt;
1026 	old_opts.s_resuid = sbi->s_resuid;
1027 	old_opts.s_resgid = sbi->s_resgid;
1028 
1029 	/*
1030 	 * Allow the "check" option to be passed as a remount option.
1031 	 */
1032 	if (!parse_options (data, sbi)) {
1033 		err = -EINVAL;
1034 		goto restore_opts;
1035 	}
1036 
1037 	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
1038 		((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
1039 
1040 	es = sbi->s_es;
1041 	if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
1042 	    (old_mount_opt & EXT2_MOUNT_XIP)) &&
1043 	    invalidate_inodes(sb))
1044 		ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
1045 			     "xip remain in cache (no functional problem)");
1046 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1047 		return 0;
1048 	if (*flags & MS_RDONLY) {
1049 		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
1050 		    !(sbi->s_mount_state & EXT2_VALID_FS))
1051 			return 0;
1052 		/*
1053 		 * OK, we are remounting a valid rw partition rdonly, so set
1054 		 * the rdonly flag and then mark the partition as valid again.
1055 		 */
1056 		es->s_state = cpu_to_le16(sbi->s_mount_state);
1057 		es->s_mtime = cpu_to_le32(get_seconds());
1058 	} else {
1059 		__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
1060 					       ~EXT2_FEATURE_RO_COMPAT_SUPP);
1061 		if (ret) {
1062 			printk("EXT2-fs: %s: couldn't remount RDWR because of "
1063 			       "unsupported optional features (%x).\n",
1064 			       sb->s_id, le32_to_cpu(ret));
1065 			err = -EROFS;
1066 			goto restore_opts;
1067 		}
1068 		/*
1069 		 * Mounting a RDONLY partition read-write, so reread and
1070 		 * store the current valid flag.  (It may have been changed
1071 		 * by e2fsck since we originally mounted the partition.)
1072 		 */
1073 		sbi->s_mount_state = le16_to_cpu(es->s_state);
1074 		if (!ext2_setup_super (sb, es, 0))
1075 			sb->s_flags &= ~MS_RDONLY;
1076 	}
1077 	ext2_sync_super(sb, es);
1078 	return 0;
1079 restore_opts:
1080 	sbi->s_mount_opt = old_opts.s_mount_opt;
1081 	sbi->s_resuid = old_opts.s_resuid;
1082 	sbi->s_resgid = old_opts.s_resgid;
1083 	sb->s_flags = old_sb_flags;
1084 	return err;
1085 }
1086 
1087 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
1088 {
1089 	struct super_block *sb = dentry->d_sb;
1090 	struct ext2_sb_info *sbi = EXT2_SB(sb);
1091 	struct ext2_super_block *es = sbi->s_es;
1092 	unsigned long overhead;
1093 	int i;
1094 	u64 fsid;
1095 
1096 	if (test_opt (sb, MINIX_DF))
1097 		overhead = 0;
1098 	else {
1099 		/*
1100 		 * Compute the overhead (FS structures)
1101 		 */
1102 
1103 		/*
1104 		 * All of the blocks before first_data_block are
1105 		 * overhead
1106 		 */
1107 		overhead = le32_to_cpu(es->s_first_data_block);
1108 
1109 		/*
1110 		 * Add the overhead attributed to the superblock and
1111 		 * block group descriptors.  If the sparse superblocks
1112 		 * feature is turned on, then not all groups have this.
1113 		 */
1114 		for (i = 0; i < sbi->s_groups_count; i++)
1115 			overhead += ext2_bg_has_super(sb, i) +
1116 				ext2_bg_num_gdb(sb, i);
1117 
1118 		/*
1119 		 * Every block group has an inode bitmap, a block
1120 		 * bitmap, and an inode table.
1121 		 */
1122 		overhead += (sbi->s_groups_count *
1123 			     (2 + sbi->s_itb_per_group));
1124 	}
1125 
1126 	buf->f_type = EXT2_SUPER_MAGIC;
1127 	buf->f_bsize = sb->s_blocksize;
1128 	buf->f_blocks = le32_to_cpu(es->s_blocks_count) - overhead;
1129 	buf->f_bfree = ext2_count_free_blocks(sb);
1130 	buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
1131 	if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
1132 		buf->f_bavail = 0;
1133 	buf->f_files = le32_to_cpu(es->s_inodes_count);
1134 	buf->f_ffree = ext2_count_free_inodes(sb);
1135 	buf->f_namelen = EXT2_NAME_LEN;
1136 	fsid = le64_to_cpup((void *)es->s_uuid) ^
1137 	       le64_to_cpup((void *)es->s_uuid + sizeof(u64));
1138 	buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
1139 	buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
1140 	return 0;
1141 }
1142 
1143 static int ext2_get_sb(struct file_system_type *fs_type,
1144 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
1145 {
1146 	return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
1147 }
1148 
1149 #ifdef CONFIG_QUOTA
1150 
1151 /* Read data from quotafile - avoid pagecache and such because we cannot afford
1152  * acquiring the locks... As quota files are never truncated and quota code
1153  * itself serializes the operations (and noone else should touch the files)
1154  * we don't have to be afraid of races */
1155 static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
1156 			       size_t len, loff_t off)
1157 {
1158 	struct inode *inode = sb_dqopt(sb)->files[type];
1159 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1160 	int err = 0;
1161 	int offset = off & (sb->s_blocksize - 1);
1162 	int tocopy;
1163 	size_t toread;
1164 	struct buffer_head tmp_bh;
1165 	struct buffer_head *bh;
1166 	loff_t i_size = i_size_read(inode);
1167 
1168 	if (off > i_size)
1169 		return 0;
1170 	if (off+len > i_size)
1171 		len = i_size-off;
1172 	toread = len;
1173 	while (toread > 0) {
1174 		tocopy = sb->s_blocksize - offset < toread ?
1175 				sb->s_blocksize - offset : toread;
1176 
1177 		tmp_bh.b_state = 0;
1178 		err = ext2_get_block(inode, blk, &tmp_bh, 0);
1179 		if (err)
1180 			return err;
1181 		if (!buffer_mapped(&tmp_bh))	/* A hole? */
1182 			memset(data, 0, tocopy);
1183 		else {
1184 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1185 			if (!bh)
1186 				return -EIO;
1187 			memcpy(data, bh->b_data+offset, tocopy);
1188 			brelse(bh);
1189 		}
1190 		offset = 0;
1191 		toread -= tocopy;
1192 		data += tocopy;
1193 		blk++;
1194 	}
1195 	return len;
1196 }
1197 
1198 /* Write to quotafile */
1199 static ssize_t ext2_quota_write(struct super_block *sb, int type,
1200 				const char *data, size_t len, loff_t off)
1201 {
1202 	struct inode *inode = sb_dqopt(sb)->files[type];
1203 	sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
1204 	int err = 0;
1205 	int offset = off & (sb->s_blocksize - 1);
1206 	int tocopy;
1207 	size_t towrite = len;
1208 	struct buffer_head tmp_bh;
1209 	struct buffer_head *bh;
1210 
1211 	mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
1212 	while (towrite > 0) {
1213 		tocopy = sb->s_blocksize - offset < towrite ?
1214 				sb->s_blocksize - offset : towrite;
1215 
1216 		tmp_bh.b_state = 0;
1217 		err = ext2_get_block(inode, blk, &tmp_bh, 1);
1218 		if (err)
1219 			goto out;
1220 		if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
1221 			bh = sb_bread(sb, tmp_bh.b_blocknr);
1222 		else
1223 			bh = sb_getblk(sb, tmp_bh.b_blocknr);
1224 		if (!bh) {
1225 			err = -EIO;
1226 			goto out;
1227 		}
1228 		lock_buffer(bh);
1229 		memcpy(bh->b_data+offset, data, tocopy);
1230 		flush_dcache_page(bh->b_page);
1231 		set_buffer_uptodate(bh);
1232 		mark_buffer_dirty(bh);
1233 		unlock_buffer(bh);
1234 		brelse(bh);
1235 		offset = 0;
1236 		towrite -= tocopy;
1237 		data += tocopy;
1238 		blk++;
1239 	}
1240 out:
1241 	if (len == towrite)
1242 		return err;
1243 	if (inode->i_size < off+len-towrite)
1244 		i_size_write(inode, off+len-towrite);
1245 	inode->i_version++;
1246 	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1247 	mark_inode_dirty(inode);
1248 	mutex_unlock(&inode->i_mutex);
1249 	return len - towrite;
1250 }
1251 
1252 #endif
1253 
1254 static struct file_system_type ext2_fs_type = {
1255 	.owner		= THIS_MODULE,
1256 	.name		= "ext2",
1257 	.get_sb		= ext2_get_sb,
1258 	.kill_sb	= kill_block_super,
1259 	.fs_flags	= FS_REQUIRES_DEV,
1260 };
1261 
1262 static int __init init_ext2_fs(void)
1263 {
1264 	int err = init_ext2_xattr();
1265 	if (err)
1266 		return err;
1267 	err = init_inodecache();
1268 	if (err)
1269 		goto out1;
1270         err = register_filesystem(&ext2_fs_type);
1271 	if (err)
1272 		goto out;
1273 	return 0;
1274 out:
1275 	destroy_inodecache();
1276 out1:
1277 	exit_ext2_xattr();
1278 	return err;
1279 }
1280 
1281 static void __exit exit_ext2_fs(void)
1282 {
1283 	unregister_filesystem(&ext2_fs_type);
1284 	destroy_inodecache();
1285 	exit_ext2_xattr();
1286 }
1287 
1288 module_init(init_ext2_fs)
1289 module_exit(exit_ext2_fs)
1290