1 /*
2  * This file is part of UBIFS.
3  *
4  * Copyright (C) 2006-2008 Nokia Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License version 2 as published by
8  * the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
13  * more details.
14  *
15  * You should have received a copy of the GNU General Public License along with
16  * this program; if not, write to the Free Software Foundation, Inc., 51
17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18  *
19  * Authors: Artem Bityutskiy (Битюцкий Артём)
20  *          Adrian Hunter
21  */
22 
23 /*
24  * This file implements UBIFS superblock. The superblock is stored at the first
25  * LEB of the volume and is never changed by UBIFS. Only user-space tools may
26  * change it. The superblock node mostly contains geometry information.
27  */
28 
29 #include "ubifs.h"
30 #include <linux/slab.h>
31 #include <linux/random.h>
32 #include <linux/math64.h>
33 
34 /*
35  * Default journal size in logical eraseblocks as a percent of total
36  * flash size.
37  */
38 #define DEFAULT_JNL_PERCENT 5
39 
40 /* Default maximum journal size in bytes */
41 #define DEFAULT_MAX_JNL (32*1024*1024)
42 
43 /* Default indexing tree fanout */
44 #define DEFAULT_FANOUT 8
45 
46 /* Default number of data journal heads */
47 #define DEFAULT_JHEADS_CNT 1
48 
49 /* Default positions of different LEBs in the main area */
50 #define DEFAULT_IDX_LEB  0
51 #define DEFAULT_DATA_LEB 1
52 #define DEFAULT_GC_LEB   2
53 
54 /* Default number of LEB numbers in LPT's save table */
55 #define DEFAULT_LSAVE_CNT 256
56 
57 /* Default reserved pool size as a percent of maximum free space */
58 #define DEFAULT_RP_PERCENT 5
59 
60 /* The default maximum size of reserved pool in bytes */
61 #define DEFAULT_MAX_RP_SIZE (5*1024*1024)
62 
63 /* Default time granularity in nanoseconds */
64 #define DEFAULT_TIME_GRAN 1000000000
65 
66 /**
67  * create_default_filesystem - format empty UBI volume.
68  * @c: UBIFS file-system description object
69  *
70  * This function creates default empty file-system. Returns zero in case of
71  * success and a negative error code in case of failure.
72  */
create_default_filesystem(struct ubifs_info * c)73 static int create_default_filesystem(struct ubifs_info *c)
74 {
75 	struct ubifs_sb_node *sup;
76 	struct ubifs_mst_node *mst;
77 	struct ubifs_idx_node *idx;
78 	struct ubifs_branch *br;
79 	struct ubifs_ino_node *ino;
80 	struct ubifs_cs_node *cs;
81 	union ubifs_key key;
82 	int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
83 	int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
84 	int min_leb_cnt = UBIFS_MIN_LEB_CNT;
85 	long long tmp64, main_bytes;
86 	__le64 tmp_le64;
87 
88 	/* Some functions called from here depend on the @c->key_len filed */
89 	c->key_len = UBIFS_SK_LEN;
90 
91 	/*
92 	 * First of all, we have to calculate default file-system geometry -
93 	 * log size, journal size, etc.
94 	 */
95 	if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
96 		/* We can first multiply then divide and have no overflow */
97 		jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
98 	else
99 		jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
100 
101 	if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
102 		jnl_lebs = UBIFS_MIN_JNL_LEBS;
103 	if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
104 		jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
105 
106 	/*
107 	 * The log should be large enough to fit reference nodes for all bud
108 	 * LEBs. Because buds do not have to start from the beginning of LEBs
109 	 * (half of the LEB may contain committed data), the log should
110 	 * generally be larger, make it twice as large.
111 	 */
112 	tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
113 	log_lebs = tmp / c->leb_size;
114 	/* Plus one LEB reserved for commit */
115 	log_lebs += 1;
116 	if (c->leb_cnt - min_leb_cnt > 8) {
117 		/* And some extra space to allow writes while committing */
118 		log_lebs += 1;
119 		min_leb_cnt += 1;
120 	}
121 
122 	max_buds = jnl_lebs - log_lebs;
123 	if (max_buds < UBIFS_MIN_BUD_LEBS)
124 		max_buds = UBIFS_MIN_BUD_LEBS;
125 
126 	/*
127 	 * Orphan nodes are stored in a separate area. One node can store a lot
128 	 * of orphan inode numbers, but when new orphan comes we just add a new
129 	 * orphan node. At some point the nodes are consolidated into one
130 	 * orphan node.
131 	 */
132 	orph_lebs = UBIFS_MIN_ORPH_LEBS;
133 #ifdef CONFIG_UBIFS_FS_DEBUG
134 	if (c->leb_cnt - min_leb_cnt > 1)
135 		/*
136 		 * For debugging purposes it is better to have at least 2
137 		 * orphan LEBs, because the orphan subsystem would need to do
138 		 * consolidations and would be stressed more.
139 		 */
140 		orph_lebs += 1;
141 #endif
142 
143 	main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
144 	main_lebs -= orph_lebs;
145 
146 	lpt_first = UBIFS_LOG_LNUM + log_lebs;
147 	c->lsave_cnt = DEFAULT_LSAVE_CNT;
148 	c->max_leb_cnt = c->leb_cnt;
149 	err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
150 				    &big_lpt);
151 	if (err)
152 		return err;
153 
154 	dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
155 		lpt_first + lpt_lebs - 1);
156 
157 	main_first = c->leb_cnt - main_lebs;
158 
159 	/* Create default superblock */
160 	tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
161 	sup = kzalloc(tmp, GFP_KERNEL);
162 	if (!sup)
163 		return -ENOMEM;
164 
165 	tmp64 = (long long)max_buds * c->leb_size;
166 	if (big_lpt)
167 		sup_flags |= UBIFS_FLG_BIGLPT;
168 
169 	sup->ch.node_type  = UBIFS_SB_NODE;
170 	sup->key_hash      = UBIFS_KEY_HASH_R5;
171 	sup->flags         = cpu_to_le32(sup_flags);
172 	sup->min_io_size   = cpu_to_le32(c->min_io_size);
173 	sup->leb_size      = cpu_to_le32(c->leb_size);
174 	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
175 	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
176 	sup->max_bud_bytes = cpu_to_le64(tmp64);
177 	sup->log_lebs      = cpu_to_le32(log_lebs);
178 	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
179 	sup->orph_lebs     = cpu_to_le32(orph_lebs);
180 	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
181 	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
182 	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
183 	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
184 	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
185 	if (c->mount_opts.override_compr)
186 		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
187 	else
188 		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
189 
190 	generate_random_uuid(sup->uuid);
191 
192 	main_bytes = (long long)main_lebs * c->leb_size;
193 	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
194 	if (tmp64 > DEFAULT_MAX_RP_SIZE)
195 		tmp64 = DEFAULT_MAX_RP_SIZE;
196 	sup->rp_size = cpu_to_le64(tmp64);
197 	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
198 
199 	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0, UBI_LONGTERM);
200 	kfree(sup);
201 	if (err)
202 		return err;
203 
204 	dbg_gen("default superblock created at LEB 0:0");
205 
206 	/* Create default master node */
207 	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
208 	if (!mst)
209 		return -ENOMEM;
210 
211 	mst->ch.node_type = UBIFS_MST_NODE;
212 	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
213 	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
214 	mst->cmt_no       = 0;
215 	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
216 	mst->root_offs    = 0;
217 	tmp = ubifs_idx_node_sz(c, 1);
218 	mst->root_len     = cpu_to_le32(tmp);
219 	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
220 	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
221 	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
222 	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
223 	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
224 	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
225 	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
226 	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
227 	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
228 	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
229 	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
230 	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
231 	mst->lscan_lnum   = cpu_to_le32(main_first);
232 	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
233 	mst->idx_lebs     = cpu_to_le32(1);
234 	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
235 
236 	/* Calculate lprops statistics */
237 	tmp64 = main_bytes;
238 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
239 	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
240 	mst->total_free = cpu_to_le64(tmp64);
241 
242 	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
243 	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
244 			  UBIFS_INO_NODE_SZ;
245 	tmp64 += ino_waste;
246 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
247 	mst->total_dirty = cpu_to_le64(tmp64);
248 
249 	/*  The indexing LEB does not contribute to dark space */
250 	tmp64 = (c->main_lebs - 1) * c->dark_wm;
251 	mst->total_dark = cpu_to_le64(tmp64);
252 
253 	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
254 
255 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0,
256 			       UBI_UNKNOWN);
257 	if (err) {
258 		kfree(mst);
259 		return err;
260 	}
261 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1, 0,
262 			       UBI_UNKNOWN);
263 	kfree(mst);
264 	if (err)
265 		return err;
266 
267 	dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
268 
269 	/* Create the root indexing node */
270 	tmp = ubifs_idx_node_sz(c, 1);
271 	idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
272 	if (!idx)
273 		return -ENOMEM;
274 
275 	c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
276 	c->key_hash = key_r5_hash;
277 
278 	idx->ch.node_type = UBIFS_IDX_NODE;
279 	idx->child_cnt = cpu_to_le16(1);
280 	ino_key_init(c, &key, UBIFS_ROOT_INO);
281 	br = ubifs_idx_branch(c, idx, 0);
282 	key_write_idx(c, &key, &br->key);
283 	br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
284 	br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
285 	err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0,
286 			       UBI_UNKNOWN);
287 	kfree(idx);
288 	if (err)
289 		return err;
290 
291 	dbg_gen("default root indexing node created LEB %d:0",
292 		main_first + DEFAULT_IDX_LEB);
293 
294 	/* Create default root inode */
295 	tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
296 	ino = kzalloc(tmp, GFP_KERNEL);
297 	if (!ino)
298 		return -ENOMEM;
299 
300 	ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
301 	ino->ch.node_type = UBIFS_INO_NODE;
302 	ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
303 	ino->nlink = cpu_to_le32(2);
304 	tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
305 	ino->atime_sec   = tmp_le64;
306 	ino->ctime_sec   = tmp_le64;
307 	ino->mtime_sec   = tmp_le64;
308 	ino->atime_nsec  = 0;
309 	ino->ctime_nsec  = 0;
310 	ino->mtime_nsec  = 0;
311 	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
312 	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
313 
314 	/* Set compression enabled by default */
315 	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
316 
317 	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
318 			       main_first + DEFAULT_DATA_LEB, 0,
319 			       UBI_UNKNOWN);
320 	kfree(ino);
321 	if (err)
322 		return err;
323 
324 	dbg_gen("root inode created at LEB %d:0",
325 		main_first + DEFAULT_DATA_LEB);
326 
327 	/*
328 	 * The first node in the log has to be the commit start node. This is
329 	 * always the case during normal file-system operation. Write a fake
330 	 * commit start node to the log.
331 	 */
332 	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
333 	cs = kzalloc(tmp, GFP_KERNEL);
334 	if (!cs)
335 		return -ENOMEM;
336 
337 	cs->ch.node_type = UBIFS_CS_NODE;
338 	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM,
339 			       0, UBI_UNKNOWN);
340 	kfree(cs);
341 
342 	ubifs_msg("default file-system created");
343 	return 0;
344 }
345 
346 /**
347  * validate_sb - validate superblock node.
348  * @c: UBIFS file-system description object
349  * @sup: superblock node
350  *
351  * This function validates superblock node @sup. Since most of data was read
352  * from the superblock and stored in @c, the function validates fields in @c
353  * instead. Returns zero in case of success and %-EINVAL in case of validation
354  * failure.
355  */
validate_sb(struct ubifs_info * c,struct ubifs_sb_node * sup)356 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
357 {
358 	long long max_bytes;
359 	int err = 1, min_leb_cnt;
360 
361 	if (!c->key_hash) {
362 		err = 2;
363 		goto failed;
364 	}
365 
366 	if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
367 		err = 3;
368 		goto failed;
369 	}
370 
371 	if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
372 		ubifs_err("min. I/O unit mismatch: %d in superblock, %d real",
373 			  le32_to_cpu(sup->min_io_size), c->min_io_size);
374 		goto failed;
375 	}
376 
377 	if (le32_to_cpu(sup->leb_size) != c->leb_size) {
378 		ubifs_err("LEB size mismatch: %d in superblock, %d real",
379 			  le32_to_cpu(sup->leb_size), c->leb_size);
380 		goto failed;
381 	}
382 
383 	if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
384 	    c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
385 	    c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
386 	    c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
387 		err = 4;
388 		goto failed;
389 	}
390 
391 	/*
392 	 * Calculate minimum allowed amount of main area LEBs. This is very
393 	 * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
394 	 * have just read from the superblock.
395 	 */
396 	min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
397 	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
398 
399 	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
400 		ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, "
401 			  "%d minimum required", c->leb_cnt, c->vi.size,
402 			  min_leb_cnt);
403 		goto failed;
404 	}
405 
406 	if (c->max_leb_cnt < c->leb_cnt) {
407 		ubifs_err("max. LEB count %d less than LEB count %d",
408 			  c->max_leb_cnt, c->leb_cnt);
409 		goto failed;
410 	}
411 
412 	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
413 		err = 7;
414 		goto failed;
415 	}
416 
417 	if (c->max_bud_bytes < (long long)c->leb_size * UBIFS_MIN_BUD_LEBS ||
418 	    c->max_bud_bytes > (long long)c->leb_size * c->main_lebs) {
419 		err = 8;
420 		goto failed;
421 	}
422 
423 	if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
424 	    c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
425 		err = 9;
426 		goto failed;
427 	}
428 
429 	if (c->fanout < UBIFS_MIN_FANOUT ||
430 	    ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
431 		err = 10;
432 		goto failed;
433 	}
434 
435 	if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
436 	    c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
437 	    c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
438 		err = 11;
439 		goto failed;
440 	}
441 
442 	if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
443 	    c->orph_lebs + c->main_lebs != c->leb_cnt) {
444 		err = 12;
445 		goto failed;
446 	}
447 
448 	if (c->default_compr < 0 || c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
449 		err = 13;
450 		goto failed;
451 	}
452 
453 	max_bytes = c->main_lebs * (long long)c->leb_size;
454 	if (c->rp_size < 0 || max_bytes < c->rp_size) {
455 		err = 14;
456 		goto failed;
457 	}
458 
459 	if (le32_to_cpu(sup->time_gran) > 1000000000 ||
460 	    le32_to_cpu(sup->time_gran) < 1) {
461 		err = 15;
462 		goto failed;
463 	}
464 
465 	return 0;
466 
467 failed:
468 	ubifs_err("bad superblock, error %d", err);
469 	dbg_dump_node(c, sup);
470 	return -EINVAL;
471 }
472 
473 /**
474  * ubifs_read_sb_node - read superblock node.
475  * @c: UBIFS file-system description object
476  *
477  * This function returns a pointer to the superblock node or a negative error
478  * code.
479  */
ubifs_read_sb_node(struct ubifs_info * c)480 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
481 {
482 	struct ubifs_sb_node *sup;
483 	int err;
484 
485 	sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
486 	if (!sup)
487 		return ERR_PTR(-ENOMEM);
488 
489 	err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
490 			      UBIFS_SB_LNUM, 0);
491 	if (err) {
492 		kfree(sup);
493 		return ERR_PTR(err);
494 	}
495 
496 	return sup;
497 }
498 
499 /**
500  * ubifs_write_sb_node - write superblock node.
501  * @c: UBIFS file-system description object
502  * @sup: superblock node read with 'ubifs_read_sb_node()'
503  *
504  * This function returns %0 on success and a negative error code on failure.
505  */
ubifs_write_sb_node(struct ubifs_info * c,struct ubifs_sb_node * sup)506 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
507 {
508 	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
509 
510 	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
511 	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len, UBI_LONGTERM);
512 }
513 
514 /**
515  * ubifs_read_superblock - read superblock.
516  * @c: UBIFS file-system description object
517  *
518  * This function finds, reads and checks the superblock. If an empty UBI volume
519  * is being mounted, this function creates default superblock. Returns zero in
520  * case of success, and a negative error code in case of failure.
521  */
ubifs_read_superblock(struct ubifs_info * c)522 int ubifs_read_superblock(struct ubifs_info *c)
523 {
524 	int err, sup_flags;
525 	struct ubifs_sb_node *sup;
526 
527 	if (c->empty) {
528 		err = create_default_filesystem(c);
529 		if (err)
530 			return err;
531 	}
532 
533 	sup = ubifs_read_sb_node(c);
534 	if (IS_ERR(sup))
535 		return PTR_ERR(sup);
536 
537 	c->fmt_version = le32_to_cpu(sup->fmt_version);
538 	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
539 
540 	/*
541 	 * The software supports all previous versions but not future versions,
542 	 * due to the unavailability of time-travelling equipment.
543 	 */
544 	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
545 		ubifs_assert(!c->ro_media || c->ro_mount);
546 		if (!c->ro_mount ||
547 		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
548 			ubifs_err("on-flash format version is w%d/r%d, but "
549 				  "software only supports up to version "
550 				  "w%d/r%d", c->fmt_version,
551 				  c->ro_compat_version, UBIFS_FORMAT_VERSION,
552 				  UBIFS_RO_COMPAT_VERSION);
553 			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
554 				ubifs_msg("only R/O mounting is possible");
555 				err = -EROFS;
556 			} else
557 				err = -EINVAL;
558 			goto out;
559 		}
560 
561 		/*
562 		 * The FS is mounted R/O, and the media format is
563 		 * R/O-compatible with the UBIFS implementation, so we can
564 		 * mount.
565 		 */
566 		c->rw_incompat = 1;
567 	}
568 
569 	if (c->fmt_version < 3) {
570 		ubifs_err("on-flash format version %d is not supported",
571 			  c->fmt_version);
572 		err = -EINVAL;
573 		goto out;
574 	}
575 
576 	switch (sup->key_hash) {
577 	case UBIFS_KEY_HASH_R5:
578 		c->key_hash = key_r5_hash;
579 		c->key_hash_type = UBIFS_KEY_HASH_R5;
580 		break;
581 
582 	case UBIFS_KEY_HASH_TEST:
583 		c->key_hash = key_test_hash;
584 		c->key_hash_type = UBIFS_KEY_HASH_TEST;
585 		break;
586 	};
587 
588 	c->key_fmt = sup->key_fmt;
589 
590 	switch (c->key_fmt) {
591 	case UBIFS_SIMPLE_KEY_FMT:
592 		c->key_len = UBIFS_SK_LEN;
593 		break;
594 	default:
595 		ubifs_err("unsupported key format");
596 		err = -EINVAL;
597 		goto out;
598 	}
599 
600 	c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
601 	c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
602 	c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
603 	c->log_lebs      = le32_to_cpu(sup->log_lebs);
604 	c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
605 	c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
606 	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
607 	c->fanout        = le32_to_cpu(sup->fanout);
608 	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
609 	c->rp_size       = le64_to_cpu(sup->rp_size);
610 	c->rp_uid        = le32_to_cpu(sup->rp_uid);
611 	c->rp_gid        = le32_to_cpu(sup->rp_gid);
612 	sup_flags        = le32_to_cpu(sup->flags);
613 	if (!c->mount_opts.override_compr)
614 		c->default_compr = le16_to_cpu(sup->default_compr);
615 
616 	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
617 	memcpy(&c->uuid, &sup->uuid, 16);
618 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
619 
620 	/* Automatically increase file system size to the maximum size */
621 	c->old_leb_cnt = c->leb_cnt;
622 	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
623 		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
624 		if (c->ro_mount)
625 			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
626 				c->old_leb_cnt,	c->leb_cnt);
627 		else {
628 			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
629 				c->old_leb_cnt, c->leb_cnt);
630 			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
631 			err = ubifs_write_sb_node(c, sup);
632 			if (err)
633 				goto out;
634 			c->old_leb_cnt = c->leb_cnt;
635 		}
636 	}
637 
638 	c->log_bytes = (long long)c->log_lebs * c->leb_size;
639 	c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
640 	c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
641 	c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
642 	c->orph_first = c->lpt_last + 1;
643 	c->orph_last = c->orph_first + c->orph_lebs - 1;
644 	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
645 	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
646 	c->main_first = c->leb_cnt - c->main_lebs;
647 
648 	err = validate_sb(c, sup);
649 out:
650 	kfree(sup);
651 	return err;
652 }
653