xref: /openbmc/linux/fs/ubifs/sb.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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/random.h>
31 #include <linux/math64.h>
32 
33 /*
34  * Default journal size in logical eraseblocks as a percent of total
35  * flash size.
36  */
37 #define DEFAULT_JNL_PERCENT 5
38 
39 /* Default maximum journal size in bytes */
40 #define DEFAULT_MAX_JNL (32*1024*1024)
41 
42 /* Default indexing tree fanout */
43 #define DEFAULT_FANOUT 8
44 
45 /* Default number of data journal heads */
46 #define DEFAULT_JHEADS_CNT 1
47 
48 /* Default positions of different LEBs in the main area */
49 #define DEFAULT_IDX_LEB  0
50 #define DEFAULT_DATA_LEB 1
51 #define DEFAULT_GC_LEB   2
52 
53 /* Default number of LEB numbers in LPT's save table */
54 #define DEFAULT_LSAVE_CNT 256
55 
56 /* Default reserved pool size as a percent of maximum free space */
57 #define DEFAULT_RP_PERCENT 5
58 
59 /* The default maximum size of reserved pool in bytes */
60 #define DEFAULT_MAX_RP_SIZE (5*1024*1024)
61 
62 /* Default time granularity in nanoseconds */
63 #define DEFAULT_TIME_GRAN 1000000000
64 
65 /**
66  * create_default_filesystem - format empty UBI volume.
67  * @c: UBIFS file-system description object
68  *
69  * This function creates default empty file-system. Returns zero in case of
70  * success and a negative error code in case of failure.
71  */
72 static int create_default_filesystem(struct ubifs_info *c)
73 {
74 	struct ubifs_sb_node *sup;
75 	struct ubifs_mst_node *mst;
76 	struct ubifs_idx_node *idx;
77 	struct ubifs_branch *br;
78 	struct ubifs_ino_node *ino;
79 	struct ubifs_cs_node *cs;
80 	union ubifs_key key;
81 	int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
82 	int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
83 	int min_leb_cnt = UBIFS_MIN_LEB_CNT;
84 	long long tmp64, main_bytes;
85 	__le64 tmp_le64;
86 
87 	/* Some functions called from here depend on the @c->key_len filed */
88 	c->key_len = UBIFS_SK_LEN;
89 
90 	/*
91 	 * First of all, we have to calculate default file-system geometry -
92 	 * log size, journal size, etc.
93 	 */
94 	if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
95 		/* We can first multiply then divide and have no overflow */
96 		jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
97 	else
98 		jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
99 
100 	if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
101 		jnl_lebs = UBIFS_MIN_JNL_LEBS;
102 	if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
103 		jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
104 
105 	/*
106 	 * The log should be large enough to fit reference nodes for all bud
107 	 * LEBs. Because buds do not have to start from the beginning of LEBs
108 	 * (half of the LEB may contain committed data), the log should
109 	 * generally be larger, make it twice as large.
110 	 */
111 	tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
112 	log_lebs = tmp / c->leb_size;
113 	/* Plus one LEB reserved for commit */
114 	log_lebs += 1;
115 	if (c->leb_cnt - min_leb_cnt > 8) {
116 		/* And some extra space to allow writes while committing */
117 		log_lebs += 1;
118 		min_leb_cnt += 1;
119 	}
120 
121 	max_buds = jnl_lebs - log_lebs;
122 	if (max_buds < UBIFS_MIN_BUD_LEBS)
123 		max_buds = UBIFS_MIN_BUD_LEBS;
124 
125 	/*
126 	 * Orphan nodes are stored in a separate area. One node can store a lot
127 	 * of orphan inode numbers, but when new orphan comes we just add a new
128 	 * orphan node. At some point the nodes are consolidated into one
129 	 * orphan node.
130 	 */
131 	orph_lebs = UBIFS_MIN_ORPH_LEBS;
132 #ifdef CONFIG_UBIFS_FS_DEBUG
133 	if (c->leb_cnt - min_leb_cnt > 1)
134 		/*
135 		 * For debugging purposes it is better to have at least 2
136 		 * orphan LEBs, because the orphan subsystem would need to do
137 		 * consolidations and would be stressed more.
138 		 */
139 		orph_lebs += 1;
140 #endif
141 
142 	main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
143 	main_lebs -= orph_lebs;
144 
145 	lpt_first = UBIFS_LOG_LNUM + log_lebs;
146 	c->lsave_cnt = DEFAULT_LSAVE_CNT;
147 	c->max_leb_cnt = c->leb_cnt;
148 	err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
149 				    &big_lpt);
150 	if (err)
151 		return err;
152 
153 	dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
154 		lpt_first + lpt_lebs - 1);
155 
156 	main_first = c->leb_cnt - main_lebs;
157 
158 	/* Create default superblock */
159 	tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
160 	sup = kzalloc(tmp, GFP_KERNEL);
161 	if (!sup)
162 		return -ENOMEM;
163 
164 	tmp64 = (long long)max_buds * c->leb_size;
165 	if (big_lpt)
166 		sup_flags |= UBIFS_FLG_BIGLPT;
167 
168 	sup->ch.node_type  = UBIFS_SB_NODE;
169 	sup->key_hash      = UBIFS_KEY_HASH_R5;
170 	sup->flags         = cpu_to_le32(sup_flags);
171 	sup->min_io_size   = cpu_to_le32(c->min_io_size);
172 	sup->leb_size      = cpu_to_le32(c->leb_size);
173 	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
174 	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
175 	sup->max_bud_bytes = cpu_to_le64(tmp64);
176 	sup->log_lebs      = cpu_to_le32(log_lebs);
177 	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
178 	sup->orph_lebs     = cpu_to_le32(orph_lebs);
179 	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
180 	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
181 	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
182 	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
183 	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
184 	if (c->mount_opts.override_compr)
185 		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
186 	else
187 		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
188 
189 	generate_random_uuid(sup->uuid);
190 
191 	main_bytes = (long long)main_lebs * c->leb_size;
192 	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
193 	if (tmp64 > DEFAULT_MAX_RP_SIZE)
194 		tmp64 = DEFAULT_MAX_RP_SIZE;
195 	sup->rp_size = cpu_to_le64(tmp64);
196 	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
197 
198 	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0, UBI_LONGTERM);
199 	kfree(sup);
200 	if (err)
201 		return err;
202 
203 	dbg_gen("default superblock created at LEB 0:0");
204 
205 	/* Create default master node */
206 	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
207 	if (!mst)
208 		return -ENOMEM;
209 
210 	mst->ch.node_type = UBIFS_MST_NODE;
211 	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
212 	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
213 	mst->cmt_no       = 0;
214 	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
215 	mst->root_offs    = 0;
216 	tmp = ubifs_idx_node_sz(c, 1);
217 	mst->root_len     = cpu_to_le32(tmp);
218 	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
219 	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
220 	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
221 	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
222 	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
223 	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
224 	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
225 	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
226 	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
227 	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
228 	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
229 	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
230 	mst->lscan_lnum   = cpu_to_le32(main_first);
231 	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
232 	mst->idx_lebs     = cpu_to_le32(1);
233 	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
234 
235 	/* Calculate lprops statistics */
236 	tmp64 = main_bytes;
237 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
238 	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
239 	mst->total_free = cpu_to_le64(tmp64);
240 
241 	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
242 	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
243 			  UBIFS_INO_NODE_SZ;
244 	tmp64 += ino_waste;
245 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
246 	mst->total_dirty = cpu_to_le64(tmp64);
247 
248 	/*  The indexing LEB does not contribute to dark space */
249 	tmp64 = (c->main_lebs - 1) * c->dark_wm;
250 	mst->total_dark = cpu_to_le64(tmp64);
251 
252 	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
253 
254 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0,
255 			       UBI_UNKNOWN);
256 	if (err) {
257 		kfree(mst);
258 		return err;
259 	}
260 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1, 0,
261 			       UBI_UNKNOWN);
262 	kfree(mst);
263 	if (err)
264 		return err;
265 
266 	dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
267 
268 	/* Create the root indexing node */
269 	tmp = ubifs_idx_node_sz(c, 1);
270 	idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
271 	if (!idx)
272 		return -ENOMEM;
273 
274 	c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
275 	c->key_hash = key_r5_hash;
276 
277 	idx->ch.node_type = UBIFS_IDX_NODE;
278 	idx->child_cnt = cpu_to_le16(1);
279 	ino_key_init(c, &key, UBIFS_ROOT_INO);
280 	br = ubifs_idx_branch(c, idx, 0);
281 	key_write_idx(c, &key, &br->key);
282 	br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
283 	br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
284 	err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0,
285 			       UBI_UNKNOWN);
286 	kfree(idx);
287 	if (err)
288 		return err;
289 
290 	dbg_gen("default root indexing node created LEB %d:0",
291 		main_first + DEFAULT_IDX_LEB);
292 
293 	/* Create default root inode */
294 	tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
295 	ino = kzalloc(tmp, GFP_KERNEL);
296 	if (!ino)
297 		return -ENOMEM;
298 
299 	ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
300 	ino->ch.node_type = UBIFS_INO_NODE;
301 	ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
302 	ino->nlink = cpu_to_le32(2);
303 	tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
304 	ino->atime_sec   = tmp_le64;
305 	ino->ctime_sec   = tmp_le64;
306 	ino->mtime_sec   = tmp_le64;
307 	ino->atime_nsec  = 0;
308 	ino->ctime_nsec  = 0;
309 	ino->mtime_nsec  = 0;
310 	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
311 	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
312 
313 	/* Set compression enabled by default */
314 	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
315 
316 	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
317 			       main_first + DEFAULT_DATA_LEB, 0,
318 			       UBI_UNKNOWN);
319 	kfree(ino);
320 	if (err)
321 		return err;
322 
323 	dbg_gen("root inode created at LEB %d:0",
324 		main_first + DEFAULT_DATA_LEB);
325 
326 	/*
327 	 * The first node in the log has to be the commit start node. This is
328 	 * always the case during normal file-system operation. Write a fake
329 	 * commit start node to the log.
330 	 */
331 	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
332 	cs = kzalloc(tmp, GFP_KERNEL);
333 	if (!cs)
334 		return -ENOMEM;
335 
336 	cs->ch.node_type = UBIFS_CS_NODE;
337 	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM,
338 			       0, UBI_UNKNOWN);
339 	kfree(cs);
340 
341 	ubifs_msg("default file-system created");
342 	return 0;
343 }
344 
345 /**
346  * validate_sb - validate superblock node.
347  * @c: UBIFS file-system description object
348  * @sup: superblock node
349  *
350  * This function validates superblock node @sup. Since most of data was read
351  * from the superblock and stored in @c, the function validates fields in @c
352  * instead. Returns zero in case of success and %-EINVAL in case of validation
353  * failure.
354  */
355 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
356 {
357 	long long max_bytes;
358 	int err = 1, min_leb_cnt;
359 
360 	if (!c->key_hash) {
361 		err = 2;
362 		goto failed;
363 	}
364 
365 	if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
366 		err = 3;
367 		goto failed;
368 	}
369 
370 	if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
371 		ubifs_err("min. I/O unit mismatch: %d in superblock, %d real",
372 			  le32_to_cpu(sup->min_io_size), c->min_io_size);
373 		goto failed;
374 	}
375 
376 	if (le32_to_cpu(sup->leb_size) != c->leb_size) {
377 		ubifs_err("LEB size mismatch: %d in superblock, %d real",
378 			  le32_to_cpu(sup->leb_size), c->leb_size);
379 		goto failed;
380 	}
381 
382 	if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
383 	    c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
384 	    c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
385 	    c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
386 		err = 4;
387 		goto failed;
388 	}
389 
390 	/*
391 	 * Calculate minimum allowed amount of main area LEBs. This is very
392 	 * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
393 	 * have just read from the superblock.
394 	 */
395 	min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
396 	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
397 
398 	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
399 		ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, "
400 			  "%d minimum required", c->leb_cnt, c->vi.size,
401 			  min_leb_cnt);
402 		goto failed;
403 	}
404 
405 	if (c->max_leb_cnt < c->leb_cnt) {
406 		ubifs_err("max. LEB count %d less than LEB count %d",
407 			  c->max_leb_cnt, c->leb_cnt);
408 		goto failed;
409 	}
410 
411 	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
412 		err = 7;
413 		goto failed;
414 	}
415 
416 	if (c->max_bud_bytes < (long long)c->leb_size * UBIFS_MIN_BUD_LEBS ||
417 	    c->max_bud_bytes > (long long)c->leb_size * c->main_lebs) {
418 		err = 8;
419 		goto failed;
420 	}
421 
422 	if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
423 	    c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
424 		err = 9;
425 		goto failed;
426 	}
427 
428 	if (c->fanout < UBIFS_MIN_FANOUT ||
429 	    ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
430 		err = 10;
431 		goto failed;
432 	}
433 
434 	if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
435 	    c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
436 	    c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
437 		err = 11;
438 		goto failed;
439 	}
440 
441 	if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
442 	    c->orph_lebs + c->main_lebs != c->leb_cnt) {
443 		err = 12;
444 		goto failed;
445 	}
446 
447 	if (c->default_compr < 0 || c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
448 		err = 13;
449 		goto failed;
450 	}
451 
452 	max_bytes = c->main_lebs * (long long)c->leb_size;
453 	if (c->rp_size < 0 || max_bytes < c->rp_size) {
454 		err = 14;
455 		goto failed;
456 	}
457 
458 	if (le32_to_cpu(sup->time_gran) > 1000000000 ||
459 	    le32_to_cpu(sup->time_gran) < 1) {
460 		err = 15;
461 		goto failed;
462 	}
463 
464 	return 0;
465 
466 failed:
467 	ubifs_err("bad superblock, error %d", err);
468 	dbg_dump_node(c, sup);
469 	return -EINVAL;
470 }
471 
472 /**
473  * ubifs_read_sb_node - read superblock node.
474  * @c: UBIFS file-system description object
475  *
476  * This function returns a pointer to the superblock node or a negative error
477  * code.
478  */
479 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
480 {
481 	struct ubifs_sb_node *sup;
482 	int err;
483 
484 	sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
485 	if (!sup)
486 		return ERR_PTR(-ENOMEM);
487 
488 	err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
489 			      UBIFS_SB_LNUM, 0);
490 	if (err) {
491 		kfree(sup);
492 		return ERR_PTR(err);
493 	}
494 
495 	return sup;
496 }
497 
498 /**
499  * ubifs_write_sb_node - write superblock node.
500  * @c: UBIFS file-system description object
501  * @sup: superblock node read with 'ubifs_read_sb_node()'
502  *
503  * This function returns %0 on success and a negative error code on failure.
504  */
505 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
506 {
507 	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
508 
509 	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
510 	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len, UBI_LONGTERM);
511 }
512 
513 /**
514  * ubifs_read_superblock - read superblock.
515  * @c: UBIFS file-system description object
516  *
517  * This function finds, reads and checks the superblock. If an empty UBI volume
518  * is being mounted, this function creates default superblock. Returns zero in
519  * case of success, and a negative error code in case of failure.
520  */
521 int ubifs_read_superblock(struct ubifs_info *c)
522 {
523 	int err, sup_flags;
524 	struct ubifs_sb_node *sup;
525 
526 	if (c->empty) {
527 		err = create_default_filesystem(c);
528 		if (err)
529 			return err;
530 	}
531 
532 	sup = ubifs_read_sb_node(c);
533 	if (IS_ERR(sup))
534 		return PTR_ERR(sup);
535 
536 	c->fmt_version = le32_to_cpu(sup->fmt_version);
537 	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
538 
539 	/*
540 	 * The software supports all previous versions but not future versions,
541 	 * due to the unavailability of time-travelling equipment.
542 	 */
543 	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
544 		struct super_block *sb = c->vfs_sb;
545 		int mounting_ro = sb->s_flags & MS_RDONLY;
546 
547 		ubifs_assert(!c->ro_media || mounting_ro);
548 		if (!mounting_ro ||
549 		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
550 			ubifs_err("on-flash format version is w%d/r%d, but "
551 				  "software only supports up to version "
552 				  "w%d/r%d", c->fmt_version,
553 				  c->ro_compat_version, UBIFS_FORMAT_VERSION,
554 				  UBIFS_RO_COMPAT_VERSION);
555 			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
556 				ubifs_msg("only R/O mounting is possible");
557 				err = -EROFS;
558 			} else
559 				err = -EINVAL;
560 			goto out;
561 		}
562 
563 		/*
564 		 * The FS is mounted R/O, and the media format is
565 		 * R/O-compatible with the UBIFS implementation, so we can
566 		 * mount.
567 		 */
568 		c->rw_incompat = 1;
569 	}
570 
571 	if (c->fmt_version < 3) {
572 		ubifs_err("on-flash format version %d is not supported",
573 			  c->fmt_version);
574 		err = -EINVAL;
575 		goto out;
576 	}
577 
578 	switch (sup->key_hash) {
579 	case UBIFS_KEY_HASH_R5:
580 		c->key_hash = key_r5_hash;
581 		c->key_hash_type = UBIFS_KEY_HASH_R5;
582 		break;
583 
584 	case UBIFS_KEY_HASH_TEST:
585 		c->key_hash = key_test_hash;
586 		c->key_hash_type = UBIFS_KEY_HASH_TEST;
587 		break;
588 	};
589 
590 	c->key_fmt = sup->key_fmt;
591 
592 	switch (c->key_fmt) {
593 	case UBIFS_SIMPLE_KEY_FMT:
594 		c->key_len = UBIFS_SK_LEN;
595 		break;
596 	default:
597 		ubifs_err("unsupported key format");
598 		err = -EINVAL;
599 		goto out;
600 	}
601 
602 	c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
603 	c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
604 	c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
605 	c->log_lebs      = le32_to_cpu(sup->log_lebs);
606 	c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
607 	c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
608 	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
609 	c->fanout        = le32_to_cpu(sup->fanout);
610 	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
611 	c->rp_size       = le64_to_cpu(sup->rp_size);
612 	c->rp_uid        = le32_to_cpu(sup->rp_uid);
613 	c->rp_gid        = le32_to_cpu(sup->rp_gid);
614 	sup_flags        = le32_to_cpu(sup->flags);
615 	if (!c->mount_opts.override_compr)
616 		c->default_compr = le16_to_cpu(sup->default_compr);
617 
618 	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
619 	memcpy(&c->uuid, &sup->uuid, 16);
620 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
621 
622 	/* Automatically increase file system size to the maximum size */
623 	c->old_leb_cnt = c->leb_cnt;
624 	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
625 		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
626 		if (c->vfs_sb->s_flags & MS_RDONLY)
627 			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
628 				c->old_leb_cnt,	c->leb_cnt);
629 		else {
630 			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
631 				c->old_leb_cnt, c->leb_cnt);
632 			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
633 			err = ubifs_write_sb_node(c, sup);
634 			if (err)
635 				goto out;
636 			c->old_leb_cnt = c->leb_cnt;
637 		}
638 	}
639 
640 	c->log_bytes = (long long)c->log_lebs * c->leb_size;
641 	c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
642 	c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
643 	c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
644 	c->orph_first = c->lpt_last + 1;
645 	c->orph_last = c->orph_first + c->orph_lebs - 1;
646 	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
647 	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
648 	c->main_first = c->leb_cnt - c->main_lebs;
649 
650 	err = validate_sb(c, sup);
651 out:
652 	kfree(sup);
653 	return err;
654 }
655