xref: /linux/fs/ubifs/sb.c (revision cc1e6315e83db0e517dd9279050b88adc83a7eba)
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/math64.h>
32 #include <linux/uuid.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  */
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 	__le32 tmp_le32;
88 	struct timespec64 ts;
89 
90 	/* Some functions called from here depend on the @c->key_len filed */
91 	c->key_len = UBIFS_SK_LEN;
92 
93 	/*
94 	 * First of all, we have to calculate default file-system geometry -
95 	 * log size, journal size, etc.
96 	 */
97 	if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
98 		/* We can first multiply then divide and have no overflow */
99 		jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
100 	else
101 		jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
102 
103 	if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
104 		jnl_lebs = UBIFS_MIN_JNL_LEBS;
105 	if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
106 		jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
107 
108 	/*
109 	 * The log should be large enough to fit reference nodes for all bud
110 	 * LEBs. Because buds do not have to start from the beginning of LEBs
111 	 * (half of the LEB may contain committed data), the log should
112 	 * generally be larger, make it twice as large.
113 	 */
114 	tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
115 	log_lebs = tmp / c->leb_size;
116 	/* Plus one LEB reserved for commit */
117 	log_lebs += 1;
118 	if (c->leb_cnt - min_leb_cnt > 8) {
119 		/* And some extra space to allow writes while committing */
120 		log_lebs += 1;
121 		min_leb_cnt += 1;
122 	}
123 
124 	max_buds = jnl_lebs - log_lebs;
125 	if (max_buds < UBIFS_MIN_BUD_LEBS)
126 		max_buds = UBIFS_MIN_BUD_LEBS;
127 
128 	/*
129 	 * Orphan nodes are stored in a separate area. One node can store a lot
130 	 * of orphan inode numbers, but when new orphan comes we just add a new
131 	 * orphan node. At some point the nodes are consolidated into one
132 	 * orphan node.
133 	 */
134 	orph_lebs = UBIFS_MIN_ORPH_LEBS;
135 	if (c->leb_cnt - min_leb_cnt > 1)
136 		/*
137 		 * For debugging purposes it is better to have at least 2
138 		 * orphan LEBs, because the orphan subsystem would need to do
139 		 * consolidations and would be stressed more.
140 		 */
141 		orph_lebs += 1;
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 	sup_flags |= UBIFS_FLG_DOUBLE_HASH;
169 
170 	sup->ch.node_type  = UBIFS_SB_NODE;
171 	sup->key_hash      = UBIFS_KEY_HASH_R5;
172 	sup->flags         = cpu_to_le32(sup_flags);
173 	sup->min_io_size   = cpu_to_le32(c->min_io_size);
174 	sup->leb_size      = cpu_to_le32(c->leb_size);
175 	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
176 	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
177 	sup->max_bud_bytes = cpu_to_le64(tmp64);
178 	sup->log_lebs      = cpu_to_le32(log_lebs);
179 	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
180 	sup->orph_lebs     = cpu_to_le32(orph_lebs);
181 	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
182 	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
183 	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
184 	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
185 	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
186 	if (c->mount_opts.override_compr)
187 		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
188 	else
189 		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
190 
191 	generate_random_uuid(sup->uuid);
192 
193 	main_bytes = (long long)main_lebs * c->leb_size;
194 	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
195 	if (tmp64 > DEFAULT_MAX_RP_SIZE)
196 		tmp64 = DEFAULT_MAX_RP_SIZE;
197 	sup->rp_size = cpu_to_le64(tmp64);
198 	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
199 
200 	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
201 	kfree(sup);
202 	if (err)
203 		return err;
204 
205 	dbg_gen("default superblock created at LEB 0:0");
206 
207 	/* Create default master node */
208 	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
209 	if (!mst)
210 		return -ENOMEM;
211 
212 	mst->ch.node_type = UBIFS_MST_NODE;
213 	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
214 	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
215 	mst->cmt_no       = 0;
216 	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
217 	mst->root_offs    = 0;
218 	tmp = ubifs_idx_node_sz(c, 1);
219 	mst->root_len     = cpu_to_le32(tmp);
220 	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
221 	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
222 	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
223 	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
224 	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
225 	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
226 	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
227 	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
228 	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
229 	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
230 	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
231 	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
232 	mst->lscan_lnum   = cpu_to_le32(main_first);
233 	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
234 	mst->idx_lebs     = cpu_to_le32(1);
235 	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
236 
237 	/* Calculate lprops statistics */
238 	tmp64 = main_bytes;
239 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
240 	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
241 	mst->total_free = cpu_to_le64(tmp64);
242 
243 	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
244 	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
245 			  UBIFS_INO_NODE_SZ;
246 	tmp64 += ino_waste;
247 	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
248 	mst->total_dirty = cpu_to_le64(tmp64);
249 
250 	/*  The indexing LEB does not contribute to dark space */
251 	tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
252 	mst->total_dark = cpu_to_le64(tmp64);
253 
254 	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
255 
256 	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
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,
262 			       0);
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 	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 
304 	ktime_get_real_ts64(&ts);
305 	ts = timespec64_trunc(ts, DEFAULT_TIME_GRAN);
306 	tmp_le64 = cpu_to_le64(ts.tv_sec);
307 	ino->atime_sec   = tmp_le64;
308 	ino->ctime_sec   = tmp_le64;
309 	ino->mtime_sec   = tmp_le64;
310 	tmp_le32 = cpu_to_le32(ts.tv_nsec);
311 	ino->atime_nsec  = tmp_le32;
312 	ino->ctime_nsec  = tmp_le32;
313 	ino->mtime_nsec  = tmp_le32;
314 	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
315 	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
316 
317 	/* Set compression enabled by default */
318 	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
319 
320 	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
321 			       main_first + DEFAULT_DATA_LEB, 0);
322 	kfree(ino);
323 	if (err)
324 		return err;
325 
326 	dbg_gen("root inode created at LEB %d:0",
327 		main_first + DEFAULT_DATA_LEB);
328 
329 	/*
330 	 * The first node in the log has to be the commit start node. This is
331 	 * always the case during normal file-system operation. Write a fake
332 	 * commit start node to the log.
333 	 */
334 	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
335 	cs = kzalloc(tmp, GFP_KERNEL);
336 	if (!cs)
337 		return -ENOMEM;
338 
339 	cs->ch.node_type = UBIFS_CS_NODE;
340 	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
341 	kfree(cs);
342 	if (err)
343 		return err;
344 
345 	ubifs_msg(c, "default file-system created");
346 	return 0;
347 }
348 
349 /**
350  * validate_sb - validate superblock node.
351  * @c: UBIFS file-system description object
352  * @sup: superblock node
353  *
354  * This function validates superblock node @sup. Since most of data was read
355  * from the superblock and stored in @c, the function validates fields in @c
356  * instead. Returns zero in case of success and %-EINVAL in case of validation
357  * failure.
358  */
359 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
360 {
361 	long long max_bytes;
362 	int err = 1, min_leb_cnt;
363 
364 	if (!c->key_hash) {
365 		err = 2;
366 		goto failed;
367 	}
368 
369 	if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
370 		err = 3;
371 		goto failed;
372 	}
373 
374 	if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
375 		ubifs_err(c, "min. I/O unit mismatch: %d in superblock, %d real",
376 			  le32_to_cpu(sup->min_io_size), c->min_io_size);
377 		goto failed;
378 	}
379 
380 	if (le32_to_cpu(sup->leb_size) != c->leb_size) {
381 		ubifs_err(c, "LEB size mismatch: %d in superblock, %d real",
382 			  le32_to_cpu(sup->leb_size), c->leb_size);
383 		goto failed;
384 	}
385 
386 	if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
387 	    c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
388 	    c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
389 	    c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
390 		err = 4;
391 		goto failed;
392 	}
393 
394 	/*
395 	 * Calculate minimum allowed amount of main area LEBs. This is very
396 	 * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
397 	 * have just read from the superblock.
398 	 */
399 	min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
400 	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
401 
402 	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
403 		ubifs_err(c, "bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
404 			  c->leb_cnt, c->vi.size, min_leb_cnt);
405 		goto failed;
406 	}
407 
408 	if (c->max_leb_cnt < c->leb_cnt) {
409 		ubifs_err(c, "max. LEB count %d less than LEB count %d",
410 			  c->max_leb_cnt, c->leb_cnt);
411 		goto failed;
412 	}
413 
414 	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
415 		ubifs_err(c, "too few main LEBs count %d, must be at least %d",
416 			  c->main_lebs, UBIFS_MIN_MAIN_LEBS);
417 		goto failed;
418 	}
419 
420 	max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
421 	if (c->max_bud_bytes < max_bytes) {
422 		ubifs_err(c, "too small journal (%lld bytes), must be at least %lld bytes",
423 			  c->max_bud_bytes, max_bytes);
424 		goto failed;
425 	}
426 
427 	max_bytes = (long long)c->leb_size * c->main_lebs;
428 	if (c->max_bud_bytes > max_bytes) {
429 		ubifs_err(c, "too large journal size (%lld bytes), only %lld bytes available in the main area",
430 			  c->max_bud_bytes, max_bytes);
431 		goto failed;
432 	}
433 
434 	if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
435 	    c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
436 		err = 9;
437 		goto failed;
438 	}
439 
440 	if (c->fanout < UBIFS_MIN_FANOUT ||
441 	    ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
442 		err = 10;
443 		goto failed;
444 	}
445 
446 	if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
447 	    c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
448 	    c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
449 		err = 11;
450 		goto failed;
451 	}
452 
453 	if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
454 	    c->orph_lebs + c->main_lebs != c->leb_cnt) {
455 		err = 12;
456 		goto failed;
457 	}
458 
459 	if (c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
460 		err = 13;
461 		goto failed;
462 	}
463 
464 	if (c->rp_size < 0 || max_bytes < c->rp_size) {
465 		err = 14;
466 		goto failed;
467 	}
468 
469 	if (le32_to_cpu(sup->time_gran) > 1000000000 ||
470 	    le32_to_cpu(sup->time_gran) < 1) {
471 		err = 15;
472 		goto failed;
473 	}
474 
475 	if (!c->double_hash && c->fmt_version >= 5) {
476 		err = 16;
477 		goto failed;
478 	}
479 
480 	if (c->encrypted && c->fmt_version < 5) {
481 		err = 17;
482 		goto failed;
483 	}
484 
485 	return 0;
486 
487 failed:
488 	ubifs_err(c, "bad superblock, error %d", err);
489 	ubifs_dump_node(c, sup);
490 	return -EINVAL;
491 }
492 
493 /**
494  * ubifs_read_sb_node - read superblock node.
495  * @c: UBIFS file-system description object
496  *
497  * This function returns a pointer to the superblock node or a negative error
498  * code. Note, the user of this function is responsible of kfree()'ing the
499  * returned superblock buffer.
500  */
501 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
502 {
503 	struct ubifs_sb_node *sup;
504 	int err;
505 
506 	sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
507 	if (!sup)
508 		return ERR_PTR(-ENOMEM);
509 
510 	err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
511 			      UBIFS_SB_LNUM, 0);
512 	if (err) {
513 		kfree(sup);
514 		return ERR_PTR(err);
515 	}
516 
517 	return sup;
518 }
519 
520 /**
521  * ubifs_write_sb_node - write superblock node.
522  * @c: UBIFS file-system description object
523  * @sup: superblock node read with 'ubifs_read_sb_node()'
524  *
525  * This function returns %0 on success and a negative error code on failure.
526  */
527 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
528 {
529 	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
530 
531 	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
532 	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
533 }
534 
535 /**
536  * ubifs_read_superblock - read superblock.
537  * @c: UBIFS file-system description object
538  *
539  * This function finds, reads and checks the superblock. If an empty UBI volume
540  * is being mounted, this function creates default superblock. Returns zero in
541  * case of success, and a negative error code in case of failure.
542  */
543 int ubifs_read_superblock(struct ubifs_info *c)
544 {
545 	int err, sup_flags;
546 	struct ubifs_sb_node *sup;
547 
548 	if (c->empty) {
549 		err = create_default_filesystem(c);
550 		if (err)
551 			return err;
552 	}
553 
554 	sup = ubifs_read_sb_node(c);
555 	if (IS_ERR(sup))
556 		return PTR_ERR(sup);
557 
558 	c->fmt_version = le32_to_cpu(sup->fmt_version);
559 	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
560 
561 	/*
562 	 * The software supports all previous versions but not future versions,
563 	 * due to the unavailability of time-travelling equipment.
564 	 */
565 	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
566 		ubifs_assert(c, !c->ro_media || c->ro_mount);
567 		if (!c->ro_mount ||
568 		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
569 			ubifs_err(c, "on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
570 				  c->fmt_version, c->ro_compat_version,
571 				  UBIFS_FORMAT_VERSION,
572 				  UBIFS_RO_COMPAT_VERSION);
573 			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
574 				ubifs_msg(c, "only R/O mounting is possible");
575 				err = -EROFS;
576 			} else
577 				err = -EINVAL;
578 			goto out;
579 		}
580 
581 		/*
582 		 * The FS is mounted R/O, and the media format is
583 		 * R/O-compatible with the UBIFS implementation, so we can
584 		 * mount.
585 		 */
586 		c->rw_incompat = 1;
587 	}
588 
589 	if (c->fmt_version < 3) {
590 		ubifs_err(c, "on-flash format version %d is not supported",
591 			  c->fmt_version);
592 		err = -EINVAL;
593 		goto out;
594 	}
595 
596 	switch (sup->key_hash) {
597 	case UBIFS_KEY_HASH_R5:
598 		c->key_hash = key_r5_hash;
599 		c->key_hash_type = UBIFS_KEY_HASH_R5;
600 		break;
601 
602 	case UBIFS_KEY_HASH_TEST:
603 		c->key_hash = key_test_hash;
604 		c->key_hash_type = UBIFS_KEY_HASH_TEST;
605 		break;
606 	};
607 
608 	c->key_fmt = sup->key_fmt;
609 
610 	switch (c->key_fmt) {
611 	case UBIFS_SIMPLE_KEY_FMT:
612 		c->key_len = UBIFS_SK_LEN;
613 		break;
614 	default:
615 		ubifs_err(c, "unsupported key format");
616 		err = -EINVAL;
617 		goto out;
618 	}
619 
620 	c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
621 	c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
622 	c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
623 	c->log_lebs      = le32_to_cpu(sup->log_lebs);
624 	c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
625 	c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
626 	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
627 	c->fanout        = le32_to_cpu(sup->fanout);
628 	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
629 	c->rp_size       = le64_to_cpu(sup->rp_size);
630 	c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
631 	c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
632 	sup_flags        = le32_to_cpu(sup->flags);
633 	if (!c->mount_opts.override_compr)
634 		c->default_compr = le16_to_cpu(sup->default_compr);
635 
636 	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
637 	memcpy(&c->uuid, &sup->uuid, 16);
638 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
639 	c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
640 	c->double_hash = !!(sup_flags & UBIFS_FLG_DOUBLE_HASH);
641 	c->encrypted = !!(sup_flags & UBIFS_FLG_ENCRYPTION);
642 
643 	if ((sup_flags & ~UBIFS_FLG_MASK) != 0) {
644 		ubifs_err(c, "Unknown feature flags found: %#x",
645 			  sup_flags & ~UBIFS_FLG_MASK);
646 		err = -EINVAL;
647 		goto out;
648 	}
649 
650 #ifndef CONFIG_UBIFS_FS_ENCRYPTION
651 	if (c->encrypted) {
652 		ubifs_err(c, "file system contains encrypted files but UBIFS"
653 			     " was built without crypto support.");
654 		err = -EINVAL;
655 		goto out;
656 	}
657 #endif
658 
659 	/* Automatically increase file system size to the maximum size */
660 	c->old_leb_cnt = c->leb_cnt;
661 	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
662 		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
663 		if (c->ro_mount)
664 			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
665 				c->old_leb_cnt,	c->leb_cnt);
666 		else {
667 			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
668 				c->old_leb_cnt, c->leb_cnt);
669 			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
670 			err = ubifs_write_sb_node(c, sup);
671 			if (err)
672 				goto out;
673 			c->old_leb_cnt = c->leb_cnt;
674 		}
675 	}
676 
677 	c->log_bytes = (long long)c->log_lebs * c->leb_size;
678 	c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
679 	c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
680 	c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
681 	c->orph_first = c->lpt_last + 1;
682 	c->orph_last = c->orph_first + c->orph_lebs - 1;
683 	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
684 	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
685 	c->main_first = c->leb_cnt - c->main_lebs;
686 
687 	err = validate_sb(c, sup);
688 out:
689 	kfree(sup);
690 	return err;
691 }
692 
693 /**
694  * fixup_leb - fixup/unmap an LEB containing free space.
695  * @c: UBIFS file-system description object
696  * @lnum: the LEB number to fix up
697  * @len: number of used bytes in LEB (starting at offset 0)
698  *
699  * This function reads the contents of the given LEB number @lnum, then fixes
700  * it up, so that empty min. I/O units in the end of LEB are actually erased on
701  * flash (rather than being just all-0xff real data). If the LEB is completely
702  * empty, it is simply unmapped.
703  */
704 static int fixup_leb(struct ubifs_info *c, int lnum, int len)
705 {
706 	int err;
707 
708 	ubifs_assert(c, len >= 0);
709 	ubifs_assert(c, len % c->min_io_size == 0);
710 	ubifs_assert(c, len < c->leb_size);
711 
712 	if (len == 0) {
713 		dbg_mnt("unmap empty LEB %d", lnum);
714 		return ubifs_leb_unmap(c, lnum);
715 	}
716 
717 	dbg_mnt("fixup LEB %d, data len %d", lnum, len);
718 	err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
719 	if (err)
720 		return err;
721 
722 	return ubifs_leb_change(c, lnum, c->sbuf, len);
723 }
724 
725 /**
726  * fixup_free_space - find & remap all LEBs containing free space.
727  * @c: UBIFS file-system description object
728  *
729  * This function walks through all LEBs in the filesystem and fiexes up those
730  * containing free/empty space.
731  */
732 static int fixup_free_space(struct ubifs_info *c)
733 {
734 	int lnum, err = 0;
735 	struct ubifs_lprops *lprops;
736 
737 	ubifs_get_lprops(c);
738 
739 	/* Fixup LEBs in the master area */
740 	for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
741 		err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
742 		if (err)
743 			goto out;
744 	}
745 
746 	/* Unmap unused log LEBs */
747 	lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
748 	while (lnum != c->ltail_lnum) {
749 		err = fixup_leb(c, lnum, 0);
750 		if (err)
751 			goto out;
752 		lnum = ubifs_next_log_lnum(c, lnum);
753 	}
754 
755 	/*
756 	 * Fixup the log head which contains the only a CS node at the
757 	 * beginning.
758 	 */
759 	err = fixup_leb(c, c->lhead_lnum,
760 			ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
761 	if (err)
762 		goto out;
763 
764 	/* Fixup LEBs in the LPT area */
765 	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
766 		int free = c->ltab[lnum - c->lpt_first].free;
767 
768 		if (free > 0) {
769 			err = fixup_leb(c, lnum, c->leb_size - free);
770 			if (err)
771 				goto out;
772 		}
773 	}
774 
775 	/* Unmap LEBs in the orphans area */
776 	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
777 		err = fixup_leb(c, lnum, 0);
778 		if (err)
779 			goto out;
780 	}
781 
782 	/* Fixup LEBs in the main area */
783 	for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
784 		lprops = ubifs_lpt_lookup(c, lnum);
785 		if (IS_ERR(lprops)) {
786 			err = PTR_ERR(lprops);
787 			goto out;
788 		}
789 
790 		if (lprops->free > 0) {
791 			err = fixup_leb(c, lnum, c->leb_size - lprops->free);
792 			if (err)
793 				goto out;
794 		}
795 	}
796 
797 out:
798 	ubifs_release_lprops(c);
799 	return err;
800 }
801 
802 /**
803  * ubifs_fixup_free_space - find & fix all LEBs with free space.
804  * @c: UBIFS file-system description object
805  *
806  * This function fixes up LEBs containing free space on first mount, if the
807  * appropriate flag was set when the FS was created. Each LEB with one or more
808  * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
809  * the free space is actually erased. E.g., this is necessary for some NAND
810  * chips, since the free space may have been programmed like real "0xff" data
811  * (generating a non-0xff ECC), causing future writes to the not-really-erased
812  * NAND pages to behave badly. After the space is fixed up, the superblock flag
813  * is cleared, so that this is skipped for all future mounts.
814  */
815 int ubifs_fixup_free_space(struct ubifs_info *c)
816 {
817 	int err;
818 	struct ubifs_sb_node *sup;
819 
820 	ubifs_assert(c, c->space_fixup);
821 	ubifs_assert(c, !c->ro_mount);
822 
823 	ubifs_msg(c, "start fixing up free space");
824 
825 	err = fixup_free_space(c);
826 	if (err)
827 		return err;
828 
829 	sup = ubifs_read_sb_node(c);
830 	if (IS_ERR(sup))
831 		return PTR_ERR(sup);
832 
833 	/* Free-space fixup is no longer required */
834 	c->space_fixup = 0;
835 	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
836 
837 	err = ubifs_write_sb_node(c, sup);
838 	kfree(sup);
839 	if (err)
840 		return err;
841 
842 	ubifs_msg(c, "free space fixup complete");
843 	return err;
844 }
845 
846 int ubifs_enable_encryption(struct ubifs_info *c)
847 {
848 	int err;
849 	struct ubifs_sb_node *sup;
850 
851 	if (c->encrypted)
852 		return 0;
853 
854 	if (c->ro_mount || c->ro_media)
855 		return -EROFS;
856 
857 	if (c->fmt_version < 5) {
858 		ubifs_err(c, "on-flash format version 5 is needed for encryption");
859 		return -EINVAL;
860 	}
861 
862 	sup = ubifs_read_sb_node(c);
863 	if (IS_ERR(sup))
864 		return PTR_ERR(sup);
865 
866 	sup->flags |= cpu_to_le32(UBIFS_FLG_ENCRYPTION);
867 
868 	err = ubifs_write_sb_node(c, sup);
869 	if (!err)
870 		c->encrypted = 1;
871 	kfree(sup);
872 
873 	return err;
874 }
875