xref: /openbmc/u-boot/fs/ubifs/sb.c (revision baefb63a)
1 /*
2  * This file is part of UBIFS.
3  *
4  * Copyright (C) 2006-2008 Nokia Corporation.
5  *
6  * SPDX-License-Identifier:	GPL-2.0+
7  *
8  * Authors: Artem Bityutskiy (Битюцкий Артём)
9  *          Adrian Hunter
10  */
11 
12 /*
13  * This file implements UBIFS superblock. The superblock is stored at the first
14  * LEB of the volume and is never changed by UBIFS. Only user-space tools may
15  * change it. The superblock node mostly contains geometry information.
16  */
17 
18 #include "ubifs.h"
19 #ifndef __UBOOT__
20 #include <linux/slab.h>
21 #include <linux/random.h>
22 #include <linux/math64.h>
23 #else
24 
25 #include <linux/compat.h>
26 #include <linux/err.h>
27 #include <ubi_uboot.h>
28 #include <linux/stat.h>
29 #endif
30 
31 /*
32  * Default journal size in logical eraseblocks as a percent of total
33  * flash size.
34  */
35 #define DEFAULT_JNL_PERCENT 5
36 
37 /* Default maximum journal size in bytes */
38 #define DEFAULT_MAX_JNL (32*1024*1024)
39 
40 /* Default indexing tree fanout */
41 #define DEFAULT_FANOUT 8
42 
43 /* Default number of data journal heads */
44 #define DEFAULT_JHEADS_CNT 1
45 
46 /* Default positions of different LEBs in the main area */
47 #define DEFAULT_IDX_LEB  0
48 #define DEFAULT_DATA_LEB 1
49 #define DEFAULT_GC_LEB   2
50 
51 /* Default number of LEB numbers in LPT's save table */
52 #define DEFAULT_LSAVE_CNT 256
53 
54 /* Default reserved pool size as a percent of maximum free space */
55 #define DEFAULT_RP_PERCENT 5
56 
57 /* The default maximum size of reserved pool in bytes */
58 #define DEFAULT_MAX_RP_SIZE (5*1024*1024)
59 
60 /* Default time granularity in nanoseconds */
61 #define DEFAULT_TIME_GRAN 1000000000
62 
63 #ifndef __UBOOT__
64 /**
65  * create_default_filesystem - format empty UBI volume.
66  * @c: UBIFS file-system description object
67  *
68  * This function creates default empty file-system. Returns zero in case of
69  * success and a negative error code in case of failure.
70  */
71 static int create_default_filesystem(struct ubifs_info *c)
72 {
73 	struct ubifs_sb_node *sup;
74 	struct ubifs_mst_node *mst;
75 	struct ubifs_idx_node *idx;
76 	struct ubifs_branch *br;
77 	struct ubifs_ino_node *ino;
78 	struct ubifs_cs_node *cs;
79 	union ubifs_key key;
80 	int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
81 	int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
82 	int min_leb_cnt = UBIFS_MIN_LEB_CNT;
83 	long long tmp64, main_bytes;
84 	__le64 tmp_le64;
85 
86 	/* Some functions called from here depend on the @c->key_len filed */
87 	c->key_len = UBIFS_SK_LEN;
88 
89 	/*
90 	 * First of all, we have to calculate default file-system geometry -
91 	 * log size, journal size, etc.
92 	 */
93 	if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
94 		/* We can first multiply then divide and have no overflow */
95 		jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
96 	else
97 		jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
98 
99 	if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
100 		jnl_lebs = UBIFS_MIN_JNL_LEBS;
101 	if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
102 		jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
103 
104 	/*
105 	 * The log should be large enough to fit reference nodes for all bud
106 	 * LEBs. Because buds do not have to start from the beginning of LEBs
107 	 * (half of the LEB may contain committed data), the log should
108 	 * generally be larger, make it twice as large.
109 	 */
110 	tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
111 	log_lebs = tmp / c->leb_size;
112 	/* Plus one LEB reserved for commit */
113 	log_lebs += 1;
114 	if (c->leb_cnt - min_leb_cnt > 8) {
115 		/* And some extra space to allow writes while committing */
116 		log_lebs += 1;
117 		min_leb_cnt += 1;
118 	}
119 
120 	max_buds = jnl_lebs - log_lebs;
121 	if (max_buds < UBIFS_MIN_BUD_LEBS)
122 		max_buds = UBIFS_MIN_BUD_LEBS;
123 
124 	/*
125 	 * Orphan nodes are stored in a separate area. One node can store a lot
126 	 * of orphan inode numbers, but when new orphan comes we just add a new
127 	 * orphan node. At some point the nodes are consolidated into one
128 	 * orphan node.
129 	 */
130 	orph_lebs = UBIFS_MIN_ORPH_LEBS;
131 	if (c->leb_cnt - min_leb_cnt > 1)
132 		/*
133 		 * For debugging purposes it is better to have at least 2
134 		 * orphan LEBs, because the orphan subsystem would need to do
135 		 * consolidations and would be stressed more.
136 		 */
137 		orph_lebs += 1;
138 
139 	main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
140 	main_lebs -= orph_lebs;
141 
142 	lpt_first = UBIFS_LOG_LNUM + log_lebs;
143 	c->lsave_cnt = DEFAULT_LSAVE_CNT;
144 	c->max_leb_cnt = c->leb_cnt;
145 	err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
146 				    &big_lpt);
147 	if (err)
148 		return err;
149 
150 	dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
151 		lpt_first + lpt_lebs - 1);
152 
153 	main_first = c->leb_cnt - main_lebs;
154 
155 	/* Create default superblock */
156 	tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
157 	sup = kzalloc(tmp, GFP_KERNEL);
158 	if (!sup)
159 		return -ENOMEM;
160 
161 	tmp64 = (long long)max_buds * c->leb_size;
162 	if (big_lpt)
163 		sup_flags |= UBIFS_FLG_BIGLPT;
164 
165 	sup->ch.node_type  = UBIFS_SB_NODE;
166 	sup->key_hash      = UBIFS_KEY_HASH_R5;
167 	sup->flags         = cpu_to_le32(sup_flags);
168 	sup->min_io_size   = cpu_to_le32(c->min_io_size);
169 	sup->leb_size      = cpu_to_le32(c->leb_size);
170 	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
171 	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
172 	sup->max_bud_bytes = cpu_to_le64(tmp64);
173 	sup->log_lebs      = cpu_to_le32(log_lebs);
174 	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
175 	sup->orph_lebs     = cpu_to_le32(orph_lebs);
176 	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
177 	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
178 	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
179 	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
180 	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
181 	if (c->mount_opts.override_compr)
182 		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
183 	else
184 		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
185 
186 	generate_random_uuid(sup->uuid);
187 
188 	main_bytes = (long long)main_lebs * c->leb_size;
189 	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
190 	if (tmp64 > DEFAULT_MAX_RP_SIZE)
191 		tmp64 = DEFAULT_MAX_RP_SIZE;
192 	sup->rp_size = cpu_to_le64(tmp64);
193 	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
194 
195 	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
196 	kfree(sup);
197 	if (err)
198 		return err;
199 
200 	dbg_gen("default superblock created at LEB 0:0");
201 
202 	/* Create default master node */
203 	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
204 	if (!mst)
205 		return -ENOMEM;
206 
207 	mst->ch.node_type = UBIFS_MST_NODE;
208 	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
209 	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
210 	mst->cmt_no       = 0;
211 	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
212 	mst->root_offs    = 0;
213 	tmp = ubifs_idx_node_sz(c, 1);
214 	mst->root_len     = cpu_to_le32(tmp);
215 	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
216 	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
217 	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
218 	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
219 	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
220 	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
221 	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
222 	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
223 	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
224 	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
225 	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
226 	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
227 	mst->lscan_lnum   = cpu_to_le32(main_first);
228 	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
229 	mst->idx_lebs     = cpu_to_le32(1);
230 	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
231 
232 	/* Calculate lprops statistics */
233 	tmp64 = main_bytes;
234 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
235 	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
236 	mst->total_free = cpu_to_le64(tmp64);
237 
238 	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
239 	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
240 			  UBIFS_INO_NODE_SZ;
241 	tmp64 += ino_waste;
242 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
243 	mst->total_dirty = cpu_to_le64(tmp64);
244 
245 	/*  The indexing LEB does not contribute to dark space */
246 	tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
247 	mst->total_dark = cpu_to_le64(tmp64);
248 
249 	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
250 
251 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
252 	if (err) {
253 		kfree(mst);
254 		return err;
255 	}
256 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1,
257 			       0);
258 	kfree(mst);
259 	if (err)
260 		return err;
261 
262 	dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
263 
264 	/* Create the root indexing node */
265 	tmp = ubifs_idx_node_sz(c, 1);
266 	idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
267 	if (!idx)
268 		return -ENOMEM;
269 
270 	c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
271 	c->key_hash = key_r5_hash;
272 
273 	idx->ch.node_type = UBIFS_IDX_NODE;
274 	idx->child_cnt = cpu_to_le16(1);
275 	ino_key_init(c, &key, UBIFS_ROOT_INO);
276 	br = ubifs_idx_branch(c, idx, 0);
277 	key_write_idx(c, &key, &br->key);
278 	br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
279 	br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
280 	err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0);
281 	kfree(idx);
282 	if (err)
283 		return err;
284 
285 	dbg_gen("default root indexing node created LEB %d:0",
286 		main_first + DEFAULT_IDX_LEB);
287 
288 	/* Create default root inode */
289 	tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
290 	ino = kzalloc(tmp, GFP_KERNEL);
291 	if (!ino)
292 		return -ENOMEM;
293 
294 	ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
295 	ino->ch.node_type = UBIFS_INO_NODE;
296 	ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
297 	ino->nlink = cpu_to_le32(2);
298 	tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
299 	ino->atime_sec   = tmp_le64;
300 	ino->ctime_sec   = tmp_le64;
301 	ino->mtime_sec   = tmp_le64;
302 	ino->atime_nsec  = 0;
303 	ino->ctime_nsec  = 0;
304 	ino->mtime_nsec  = 0;
305 	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
306 	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
307 
308 	/* Set compression enabled by default */
309 	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
310 
311 	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
312 			       main_first + DEFAULT_DATA_LEB, 0);
313 	kfree(ino);
314 	if (err)
315 		return err;
316 
317 	dbg_gen("root inode created at LEB %d:0",
318 		main_first + DEFAULT_DATA_LEB);
319 
320 	/*
321 	 * The first node in the log has to be the commit start node. This is
322 	 * always the case during normal file-system operation. Write a fake
323 	 * commit start node to the log.
324 	 */
325 	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
326 	cs = kzalloc(tmp, GFP_KERNEL);
327 	if (!cs)
328 		return -ENOMEM;
329 
330 	cs->ch.node_type = UBIFS_CS_NODE;
331 	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
332 	kfree(cs);
333 	if (err)
334 		return err;
335 
336 	ubifs_msg(c, "default file-system created");
337 	return 0;
338 }
339 #endif
340 
341 /**
342  * validate_sb - validate superblock node.
343  * @c: UBIFS file-system description object
344  * @sup: superblock node
345  *
346  * This function validates superblock node @sup. Since most of data was read
347  * from the superblock and stored in @c, the function validates fields in @c
348  * instead. Returns zero in case of success and %-EINVAL in case of validation
349  * failure.
350  */
351 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
352 {
353 	long long max_bytes;
354 	int err = 1, min_leb_cnt;
355 
356 	if (!c->key_hash) {
357 		err = 2;
358 		goto failed;
359 	}
360 
361 	if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
362 		err = 3;
363 		goto failed;
364 	}
365 
366 	if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
367 		ubifs_err(c, "min. I/O unit mismatch: %d in superblock, %d real",
368 			  le32_to_cpu(sup->min_io_size), c->min_io_size);
369 		goto failed;
370 	}
371 
372 	if (le32_to_cpu(sup->leb_size) != c->leb_size) {
373 		ubifs_err(c, "LEB size mismatch: %d in superblock, %d real",
374 			  le32_to_cpu(sup->leb_size), c->leb_size);
375 		goto failed;
376 	}
377 
378 	if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
379 	    c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
380 	    c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
381 	    c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
382 		err = 4;
383 		goto failed;
384 	}
385 
386 	/*
387 	 * Calculate minimum allowed amount of main area LEBs. This is very
388 	 * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
389 	 * have just read from the superblock.
390 	 */
391 	min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
392 	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
393 
394 	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
395 		ubifs_err(c, "bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
396 			  c->leb_cnt, c->vi.size, min_leb_cnt);
397 		goto failed;
398 	}
399 
400 	if (c->max_leb_cnt < c->leb_cnt) {
401 		ubifs_err(c, "max. LEB count %d less than LEB count %d",
402 			  c->max_leb_cnt, c->leb_cnt);
403 		goto failed;
404 	}
405 
406 	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
407 		ubifs_err(c, "too few main LEBs count %d, must be at least %d",
408 			  c->main_lebs, UBIFS_MIN_MAIN_LEBS);
409 		goto failed;
410 	}
411 
412 	max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
413 	if (c->max_bud_bytes < max_bytes) {
414 		ubifs_err(c, "too small journal (%lld bytes), must be at least %lld bytes",
415 			  c->max_bud_bytes, max_bytes);
416 		goto failed;
417 	}
418 
419 	max_bytes = (long long)c->leb_size * c->main_lebs;
420 	if (c->max_bud_bytes > max_bytes) {
421 		ubifs_err(c, "too large journal size (%lld bytes), only %lld bytes available in the main area",
422 			  c->max_bud_bytes, max_bytes);
423 		goto failed;
424 	}
425 
426 	if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
427 	    c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
428 		err = 9;
429 		goto failed;
430 	}
431 
432 	if (c->fanout < UBIFS_MIN_FANOUT ||
433 	    ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
434 		err = 10;
435 		goto failed;
436 	}
437 
438 	if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
439 	    c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
440 	    c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
441 		err = 11;
442 		goto failed;
443 	}
444 
445 	if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
446 	    c->orph_lebs + c->main_lebs != c->leb_cnt) {
447 		err = 12;
448 		goto failed;
449 	}
450 
451 	if (c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
452 		err = 13;
453 		goto failed;
454 	}
455 
456 	if (c->rp_size < 0 || max_bytes < c->rp_size) {
457 		err = 14;
458 		goto failed;
459 	}
460 
461 	if (le32_to_cpu(sup->time_gran) > 1000000000 ||
462 	    le32_to_cpu(sup->time_gran) < 1) {
463 		err = 15;
464 		goto failed;
465 	}
466 
467 	return 0;
468 
469 failed:
470 	ubifs_err(c, "bad superblock, error %d", err);
471 	ubifs_dump_node(c, sup);
472 	return -EINVAL;
473 }
474 
475 /**
476  * ubifs_read_sb_node - read superblock node.
477  * @c: UBIFS file-system description object
478  *
479  * This function returns a pointer to the superblock node or a negative error
480  * code. Note, the user of this function is responsible of kfree()'ing the
481  * returned superblock buffer.
482  */
483 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
484 {
485 	struct ubifs_sb_node *sup;
486 	int err;
487 
488 	sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
489 	if (!sup)
490 		return ERR_PTR(-ENOMEM);
491 
492 	err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
493 			      UBIFS_SB_LNUM, 0);
494 	if (err) {
495 		kfree(sup);
496 		return ERR_PTR(err);
497 	}
498 
499 	return sup;
500 }
501 
502 /**
503  * ubifs_write_sb_node - write superblock node.
504  * @c: UBIFS file-system description object
505  * @sup: superblock node read with 'ubifs_read_sb_node()'
506  *
507  * This function returns %0 on success and a negative error code on failure.
508  */
509 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
510 {
511 	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
512 
513 	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
514 	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
515 }
516 
517 /**
518  * ubifs_read_superblock - read superblock.
519  * @c: UBIFS file-system description object
520  *
521  * This function finds, reads and checks the superblock. If an empty UBI volume
522  * is being mounted, this function creates default superblock. Returns zero in
523  * case of success, and a negative error code in case of failure.
524  */
525 int ubifs_read_superblock(struct ubifs_info *c)
526 {
527 	int err, sup_flags;
528 	struct ubifs_sb_node *sup;
529 
530 	if (c->empty) {
531 #ifndef __UBOOT__
532 		err = create_default_filesystem(c);
533 		if (err)
534 			return err;
535 #else
536 		printf("No UBIFS filesystem found!\n");
537 		return -1;
538 #endif
539 	}
540 
541 	sup = ubifs_read_sb_node(c);
542 	if (IS_ERR(sup))
543 		return PTR_ERR(sup);
544 
545 	c->fmt_version = le32_to_cpu(sup->fmt_version);
546 	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
547 
548 	/*
549 	 * The software supports all previous versions but not future versions,
550 	 * due to the unavailability of time-travelling equipment.
551 	 */
552 	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
553 		ubifs_assert(!c->ro_media || c->ro_mount);
554 		if (!c->ro_mount ||
555 		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
556 			ubifs_err(c, "on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
557 				  c->fmt_version, c->ro_compat_version,
558 				  UBIFS_FORMAT_VERSION,
559 				  UBIFS_RO_COMPAT_VERSION);
560 			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
561 				ubifs_msg(c, "only R/O mounting is possible");
562 				err = -EROFS;
563 			} else
564 				err = -EINVAL;
565 			goto out;
566 		}
567 
568 		/*
569 		 * The FS is mounted R/O, and the media format is
570 		 * R/O-compatible with the UBIFS implementation, so we can
571 		 * mount.
572 		 */
573 		c->rw_incompat = 1;
574 	}
575 
576 	if (c->fmt_version < 3) {
577 		ubifs_err(c, "on-flash format version %d is not supported",
578 			  c->fmt_version);
579 		err = -EINVAL;
580 		goto out;
581 	}
582 
583 	switch (sup->key_hash) {
584 	case UBIFS_KEY_HASH_R5:
585 		c->key_hash = key_r5_hash;
586 		c->key_hash_type = UBIFS_KEY_HASH_R5;
587 		break;
588 
589 	case UBIFS_KEY_HASH_TEST:
590 		c->key_hash = key_test_hash;
591 		c->key_hash_type = UBIFS_KEY_HASH_TEST;
592 		break;
593 	};
594 
595 	c->key_fmt = sup->key_fmt;
596 
597 	switch (c->key_fmt) {
598 	case UBIFS_SIMPLE_KEY_FMT:
599 		c->key_len = UBIFS_SK_LEN;
600 		break;
601 	default:
602 		ubifs_err(c, "unsupported key format");
603 		err = -EINVAL;
604 		goto out;
605 	}
606 
607 	c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
608 	c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
609 	c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
610 	c->log_lebs      = le32_to_cpu(sup->log_lebs);
611 	c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
612 	c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
613 	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
614 	c->fanout        = le32_to_cpu(sup->fanout);
615 	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
616 	c->rp_size       = le64_to_cpu(sup->rp_size);
617 #ifndef __UBOOT__
618 	c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
619 	c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
620 #else
621 	c->rp_uid.val    = le32_to_cpu(sup->rp_uid);
622 	c->rp_gid.val    = le32_to_cpu(sup->rp_gid);
623 #endif
624 	sup_flags        = le32_to_cpu(sup->flags);
625 	if (!c->mount_opts.override_compr)
626 		c->default_compr = le16_to_cpu(sup->default_compr);
627 
628 	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
629 	memcpy(&c->uuid, &sup->uuid, 16);
630 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
631 	c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
632 
633 	/* Automatically increase file system size to the maximum size */
634 	c->old_leb_cnt = c->leb_cnt;
635 	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
636 		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
637 		if (c->ro_mount)
638 			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
639 				c->old_leb_cnt,	c->leb_cnt);
640 #ifndef __UBOOT__
641 		else {
642 			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
643 				c->old_leb_cnt, c->leb_cnt);
644 			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
645 			err = ubifs_write_sb_node(c, sup);
646 			if (err)
647 				goto out;
648 			c->old_leb_cnt = c->leb_cnt;
649 		}
650 #endif
651 	}
652 
653 	c->log_bytes = (long long)c->log_lebs * c->leb_size;
654 	c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
655 	c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
656 	c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
657 	c->orph_first = c->lpt_last + 1;
658 	c->orph_last = c->orph_first + c->orph_lebs - 1;
659 	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
660 	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
661 	c->main_first = c->leb_cnt - c->main_lebs;
662 
663 	err = validate_sb(c, sup);
664 out:
665 	kfree(sup);
666 	return err;
667 }
668 
669 /**
670  * fixup_leb - fixup/unmap an LEB containing free space.
671  * @c: UBIFS file-system description object
672  * @lnum: the LEB number to fix up
673  * @len: number of used bytes in LEB (starting at offset 0)
674  *
675  * This function reads the contents of the given LEB number @lnum, then fixes
676  * it up, so that empty min. I/O units in the end of LEB are actually erased on
677  * flash (rather than being just all-0xff real data). If the LEB is completely
678  * empty, it is simply unmapped.
679  */
680 static int fixup_leb(struct ubifs_info *c, int lnum, int len)
681 {
682 	int err;
683 
684 	ubifs_assert(len >= 0);
685 	ubifs_assert(len % c->min_io_size == 0);
686 	ubifs_assert(len < c->leb_size);
687 
688 	if (len == 0) {
689 		dbg_mnt("unmap empty LEB %d", lnum);
690 		return ubifs_leb_unmap(c, lnum);
691 	}
692 
693 	dbg_mnt("fixup LEB %d, data len %d", lnum, len);
694 	err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
695 	if (err)
696 		return err;
697 
698 	return ubifs_leb_change(c, lnum, c->sbuf, len);
699 }
700 
701 /**
702  * fixup_free_space - find & remap all LEBs containing free space.
703  * @c: UBIFS file-system description object
704  *
705  * This function walks through all LEBs in the filesystem and fiexes up those
706  * containing free/empty space.
707  */
708 static int fixup_free_space(struct ubifs_info *c)
709 {
710 	int lnum, err = 0;
711 	struct ubifs_lprops *lprops;
712 
713 	ubifs_get_lprops(c);
714 
715 	/* Fixup LEBs in the master area */
716 	for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
717 		err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
718 		if (err)
719 			goto out;
720 	}
721 
722 	/* Unmap unused log LEBs */
723 	lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
724 	while (lnum != c->ltail_lnum) {
725 		err = fixup_leb(c, lnum, 0);
726 		if (err)
727 			goto out;
728 		lnum = ubifs_next_log_lnum(c, lnum);
729 	}
730 
731 	/*
732 	 * Fixup the log head which contains the only a CS node at the
733 	 * beginning.
734 	 */
735 	err = fixup_leb(c, c->lhead_lnum,
736 			ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
737 	if (err)
738 		goto out;
739 
740 	/* Fixup LEBs in the LPT area */
741 	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
742 		int free = c->ltab[lnum - c->lpt_first].free;
743 
744 		if (free > 0) {
745 			err = fixup_leb(c, lnum, c->leb_size - free);
746 			if (err)
747 				goto out;
748 		}
749 	}
750 
751 	/* Unmap LEBs in the orphans area */
752 	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
753 		err = fixup_leb(c, lnum, 0);
754 		if (err)
755 			goto out;
756 	}
757 
758 	/* Fixup LEBs in the main area */
759 	for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
760 		lprops = ubifs_lpt_lookup(c, lnum);
761 		if (IS_ERR(lprops)) {
762 			err = PTR_ERR(lprops);
763 			goto out;
764 		}
765 
766 		if (lprops->free > 0) {
767 			err = fixup_leb(c, lnum, c->leb_size - lprops->free);
768 			if (err)
769 				goto out;
770 		}
771 	}
772 
773 out:
774 	ubifs_release_lprops(c);
775 	return err;
776 }
777 
778 /**
779  * ubifs_fixup_free_space - find & fix all LEBs with free space.
780  * @c: UBIFS file-system description object
781  *
782  * This function fixes up LEBs containing free space on first mount, if the
783  * appropriate flag was set when the FS was created. Each LEB with one or more
784  * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
785  * the free space is actually erased. E.g., this is necessary for some NAND
786  * chips, since the free space may have been programmed like real "0xff" data
787  * (generating a non-0xff ECC), causing future writes to the not-really-erased
788  * NAND pages to behave badly. After the space is fixed up, the superblock flag
789  * is cleared, so that this is skipped for all future mounts.
790  */
791 int ubifs_fixup_free_space(struct ubifs_info *c)
792 {
793 	int err;
794 	struct ubifs_sb_node *sup;
795 
796 	ubifs_assert(c->space_fixup);
797 	ubifs_assert(!c->ro_mount);
798 
799 	ubifs_msg(c, "start fixing up free space");
800 
801 	err = fixup_free_space(c);
802 	if (err)
803 		return err;
804 
805 	sup = ubifs_read_sb_node(c);
806 	if (IS_ERR(sup))
807 		return PTR_ERR(sup);
808 
809 	/* Free-space fixup is no longer required */
810 	c->space_fixup = 0;
811 	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
812 
813 	err = ubifs_write_sb_node(c, sup);
814 	kfree(sup);
815 	if (err)
816 		return err;
817 
818 	ubifs_msg(c, "free space fixup complete");
819 	return err;
820 }
821