xref: /openbmc/linux/fs/ubifs/sb.c (revision fa7f32422ea1ac276b45b96a540ed5981caaa61f)
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  
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  	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  
141  	main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
142  	main_lebs -= orph_lebs;
143  
144  	lpt_first = UBIFS_LOG_LNUM + log_lebs;
145  	c->lsave_cnt = DEFAULT_LSAVE_CNT;
146  	c->max_leb_cnt = c->leb_cnt;
147  	err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
148  				    &big_lpt);
149  	if (err)
150  		return err;
151  
152  	dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
153  		lpt_first + lpt_lebs - 1);
154  
155  	main_first = c->leb_cnt - main_lebs;
156  
157  	/* Create default superblock */
158  	tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
159  	sup = kzalloc(tmp, GFP_KERNEL);
160  	if (!sup)
161  		return -ENOMEM;
162  
163  	tmp64 = (long long)max_buds * c->leb_size;
164  	if (big_lpt)
165  		sup_flags |= UBIFS_FLG_BIGLPT;
166  
167  	sup->ch.node_type  = UBIFS_SB_NODE;
168  	sup->key_hash      = UBIFS_KEY_HASH_R5;
169  	sup->flags         = cpu_to_le32(sup_flags);
170  	sup->min_io_size   = cpu_to_le32(c->min_io_size);
171  	sup->leb_size      = cpu_to_le32(c->leb_size);
172  	sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
173  	sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
174  	sup->max_bud_bytes = cpu_to_le64(tmp64);
175  	sup->log_lebs      = cpu_to_le32(log_lebs);
176  	sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
177  	sup->orph_lebs     = cpu_to_le32(orph_lebs);
178  	sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
179  	sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
180  	sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
181  	sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
182  	sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
183  	if (c->mount_opts.override_compr)
184  		sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
185  	else
186  		sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
187  
188  	generate_random_uuid(sup->uuid);
189  
190  	main_bytes = (long long)main_lebs * c->leb_size;
191  	tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
192  	if (tmp64 > DEFAULT_MAX_RP_SIZE)
193  		tmp64 = DEFAULT_MAX_RP_SIZE;
194  	sup->rp_size = cpu_to_le64(tmp64);
195  	sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
196  
197  	err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
198  	kfree(sup);
199  	if (err)
200  		return err;
201  
202  	dbg_gen("default superblock created at LEB 0:0");
203  
204  	/* Create default master node */
205  	mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
206  	if (!mst)
207  		return -ENOMEM;
208  
209  	mst->ch.node_type = UBIFS_MST_NODE;
210  	mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
211  	mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
212  	mst->cmt_no       = 0;
213  	mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
214  	mst->root_offs    = 0;
215  	tmp = ubifs_idx_node_sz(c, 1);
216  	mst->root_len     = cpu_to_le32(tmp);
217  	mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
218  	mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
219  	mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
220  	mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
221  	mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
222  	mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
223  	mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
224  	mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
225  	mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
226  	mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
227  	mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
228  	mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
229  	mst->lscan_lnum   = cpu_to_le32(main_first);
230  	mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
231  	mst->idx_lebs     = cpu_to_le32(1);
232  	mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
233  
234  	/* Calculate lprops statistics */
235  	tmp64 = main_bytes;
236  	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
237  	tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
238  	mst->total_free = cpu_to_le64(tmp64);
239  
240  	tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
241  	ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
242  			  UBIFS_INO_NODE_SZ;
243  	tmp64 += ino_waste;
244  	tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
245  	mst->total_dirty = cpu_to_le64(tmp64);
246  
247  	/*  The indexing LEB does not contribute to dark space */
248  	tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
249  	mst->total_dark = cpu_to_le64(tmp64);
250  
251  	mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
252  
253  	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
254  	if (err) {
255  		kfree(mst);
256  		return err;
257  	}
258  	err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1,
259  			       0);
260  	kfree(mst);
261  	if (err)
262  		return err;
263  
264  	dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
265  
266  	/* Create the root indexing node */
267  	tmp = ubifs_idx_node_sz(c, 1);
268  	idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
269  	if (!idx)
270  		return -ENOMEM;
271  
272  	c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
273  	c->key_hash = key_r5_hash;
274  
275  	idx->ch.node_type = UBIFS_IDX_NODE;
276  	idx->child_cnt = cpu_to_le16(1);
277  	ino_key_init(c, &key, UBIFS_ROOT_INO);
278  	br = ubifs_idx_branch(c, idx, 0);
279  	key_write_idx(c, &key, &br->key);
280  	br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
281  	br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
282  	err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0);
283  	kfree(idx);
284  	if (err)
285  		return err;
286  
287  	dbg_gen("default root indexing node created LEB %d:0",
288  		main_first + DEFAULT_IDX_LEB);
289  
290  	/* Create default root inode */
291  	tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
292  	ino = kzalloc(tmp, GFP_KERNEL);
293  	if (!ino)
294  		return -ENOMEM;
295  
296  	ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
297  	ino->ch.node_type = UBIFS_INO_NODE;
298  	ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
299  	ino->nlink = cpu_to_le32(2);
300  	tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
301  	ino->atime_sec   = tmp_le64;
302  	ino->ctime_sec   = tmp_le64;
303  	ino->mtime_sec   = tmp_le64;
304  	ino->atime_nsec  = 0;
305  	ino->ctime_nsec  = 0;
306  	ino->mtime_nsec  = 0;
307  	ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
308  	ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
309  
310  	/* Set compression enabled by default */
311  	ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
312  
313  	err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
314  			       main_first + DEFAULT_DATA_LEB, 0);
315  	kfree(ino);
316  	if (err)
317  		return err;
318  
319  	dbg_gen("root inode created at LEB %d:0",
320  		main_first + DEFAULT_DATA_LEB);
321  
322  	/*
323  	 * The first node in the log has to be the commit start node. This is
324  	 * always the case during normal file-system operation. Write a fake
325  	 * commit start node to the log.
326  	 */
327  	tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
328  	cs = kzalloc(tmp, GFP_KERNEL);
329  	if (!cs)
330  		return -ENOMEM;
331  
332  	cs->ch.node_type = UBIFS_CS_NODE;
333  	err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
334  	kfree(cs);
335  	if (err)
336  		return err;
337  
338  	ubifs_msg(c, "default file-system created");
339  	return 0;
340  }
341  
342  /**
343   * validate_sb - validate superblock node.
344   * @c: UBIFS file-system description object
345   * @sup: superblock node
346   *
347   * This function validates superblock node @sup. Since most of data was read
348   * from the superblock and stored in @c, the function validates fields in @c
349   * instead. Returns zero in case of success and %-EINVAL in case of validation
350   * failure.
351   */
352  static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
353  {
354  	long long max_bytes;
355  	int err = 1, min_leb_cnt;
356  
357  	if (!c->key_hash) {
358  		err = 2;
359  		goto failed;
360  	}
361  
362  	if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
363  		err = 3;
364  		goto failed;
365  	}
366  
367  	if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
368  		ubifs_err(c, "min. I/O unit mismatch: %d in superblock, %d real",
369  			  le32_to_cpu(sup->min_io_size), c->min_io_size);
370  		goto failed;
371  	}
372  
373  	if (le32_to_cpu(sup->leb_size) != c->leb_size) {
374  		ubifs_err(c, "LEB size mismatch: %d in superblock, %d real",
375  			  le32_to_cpu(sup->leb_size), c->leb_size);
376  		goto failed;
377  	}
378  
379  	if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
380  	    c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
381  	    c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
382  	    c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
383  		err = 4;
384  		goto failed;
385  	}
386  
387  	/*
388  	 * Calculate minimum allowed amount of main area LEBs. This is very
389  	 * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
390  	 * have just read from the superblock.
391  	 */
392  	min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
393  	min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
394  
395  	if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
396  		ubifs_err(c, "bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
397  			  c->leb_cnt, c->vi.size, min_leb_cnt);
398  		goto failed;
399  	}
400  
401  	if (c->max_leb_cnt < c->leb_cnt) {
402  		ubifs_err(c, "max. LEB count %d less than LEB count %d",
403  			  c->max_leb_cnt, c->leb_cnt);
404  		goto failed;
405  	}
406  
407  	if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
408  		ubifs_err(c, "too few main LEBs count %d, must be at least %d",
409  			  c->main_lebs, UBIFS_MIN_MAIN_LEBS);
410  		goto failed;
411  	}
412  
413  	max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
414  	if (c->max_bud_bytes < max_bytes) {
415  		ubifs_err(c, "too small journal (%lld bytes), must be at least %lld bytes",
416  			  c->max_bud_bytes, max_bytes);
417  		goto failed;
418  	}
419  
420  	max_bytes = (long long)c->leb_size * c->main_lebs;
421  	if (c->max_bud_bytes > max_bytes) {
422  		ubifs_err(c, "too large journal size (%lld bytes), only %lld bytes available in the main area",
423  			  c->max_bud_bytes, max_bytes);
424  		goto failed;
425  	}
426  
427  	if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
428  	    c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
429  		err = 9;
430  		goto failed;
431  	}
432  
433  	if (c->fanout < UBIFS_MIN_FANOUT ||
434  	    ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
435  		err = 10;
436  		goto failed;
437  	}
438  
439  	if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
440  	    c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
441  	    c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
442  		err = 11;
443  		goto failed;
444  	}
445  
446  	if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
447  	    c->orph_lebs + c->main_lebs != c->leb_cnt) {
448  		err = 12;
449  		goto failed;
450  	}
451  
452  	if (c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
453  		err = 13;
454  		goto failed;
455  	}
456  
457  	if (c->rp_size < 0 || max_bytes < c->rp_size) {
458  		err = 14;
459  		goto failed;
460  	}
461  
462  	if (le32_to_cpu(sup->time_gran) > 1000000000 ||
463  	    le32_to_cpu(sup->time_gran) < 1) {
464  		err = 15;
465  		goto failed;
466  	}
467  
468  	return 0;
469  
470  failed:
471  	ubifs_err(c, "bad superblock, error %d", err);
472  	ubifs_dump_node(c, sup);
473  	return -EINVAL;
474  }
475  
476  /**
477   * ubifs_read_sb_node - read superblock node.
478   * @c: UBIFS file-system description object
479   *
480   * This function returns a pointer to the superblock node or a negative error
481   * code. Note, the user of this function is responsible of kfree()'ing the
482   * returned superblock buffer.
483   */
484  struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
485  {
486  	struct ubifs_sb_node *sup;
487  	int err;
488  
489  	sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
490  	if (!sup)
491  		return ERR_PTR(-ENOMEM);
492  
493  	err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
494  			      UBIFS_SB_LNUM, 0);
495  	if (err) {
496  		kfree(sup);
497  		return ERR_PTR(err);
498  	}
499  
500  	return sup;
501  }
502  
503  /**
504   * ubifs_write_sb_node - write superblock node.
505   * @c: UBIFS file-system description object
506   * @sup: superblock node read with 'ubifs_read_sb_node()'
507   *
508   * This function returns %0 on success and a negative error code on failure.
509   */
510  int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
511  {
512  	int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
513  
514  	ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
515  	return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
516  }
517  
518  /**
519   * ubifs_read_superblock - read superblock.
520   * @c: UBIFS file-system description object
521   *
522   * This function finds, reads and checks the superblock. If an empty UBI volume
523   * is being mounted, this function creates default superblock. Returns zero in
524   * case of success, and a negative error code in case of failure.
525   */
526  int ubifs_read_superblock(struct ubifs_info *c)
527  {
528  	int err, sup_flags;
529  	struct ubifs_sb_node *sup;
530  
531  	if (c->empty) {
532  		err = create_default_filesystem(c);
533  		if (err)
534  			return err;
535  	}
536  
537  	sup = ubifs_read_sb_node(c);
538  	if (IS_ERR(sup))
539  		return PTR_ERR(sup);
540  
541  	c->fmt_version = le32_to_cpu(sup->fmt_version);
542  	c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
543  
544  	/*
545  	 * The software supports all previous versions but not future versions,
546  	 * due to the unavailability of time-travelling equipment.
547  	 */
548  	if (c->fmt_version > UBIFS_FORMAT_VERSION) {
549  		ubifs_assert(!c->ro_media || c->ro_mount);
550  		if (!c->ro_mount ||
551  		    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
552  			ubifs_err(c, "on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
553  				  c->fmt_version, c->ro_compat_version,
554  				  UBIFS_FORMAT_VERSION,
555  				  UBIFS_RO_COMPAT_VERSION);
556  			if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
557  				ubifs_msg(c, "only R/O mounting is possible");
558  				err = -EROFS;
559  			} else
560  				err = -EINVAL;
561  			goto out;
562  		}
563  
564  		/*
565  		 * The FS is mounted R/O, and the media format is
566  		 * R/O-compatible with the UBIFS implementation, so we can
567  		 * mount.
568  		 */
569  		c->rw_incompat = 1;
570  	}
571  
572  	if (c->fmt_version < 3) {
573  		ubifs_err(c, "on-flash format version %d is not supported",
574  			  c->fmt_version);
575  		err = -EINVAL;
576  		goto out;
577  	}
578  
579  	switch (sup->key_hash) {
580  	case UBIFS_KEY_HASH_R5:
581  		c->key_hash = key_r5_hash;
582  		c->key_hash_type = UBIFS_KEY_HASH_R5;
583  		break;
584  
585  	case UBIFS_KEY_HASH_TEST:
586  		c->key_hash = key_test_hash;
587  		c->key_hash_type = UBIFS_KEY_HASH_TEST;
588  		break;
589  	};
590  
591  	c->key_fmt = sup->key_fmt;
592  
593  	switch (c->key_fmt) {
594  	case UBIFS_SIMPLE_KEY_FMT:
595  		c->key_len = UBIFS_SK_LEN;
596  		break;
597  	default:
598  		ubifs_err(c, "unsupported key format");
599  		err = -EINVAL;
600  		goto out;
601  	}
602  
603  	c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
604  	c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
605  	c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
606  	c->log_lebs      = le32_to_cpu(sup->log_lebs);
607  	c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
608  	c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
609  	c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
610  	c->fanout        = le32_to_cpu(sup->fanout);
611  	c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
612  	c->rp_size       = le64_to_cpu(sup->rp_size);
613  	c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
614  	c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
615  	sup_flags        = le32_to_cpu(sup->flags);
616  	if (!c->mount_opts.override_compr)
617  		c->default_compr = le16_to_cpu(sup->default_compr);
618  
619  	c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
620  	memcpy(&c->uuid, &sup->uuid, 16);
621  	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
622  	c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
623  
624  	/* Automatically increase file system size to the maximum size */
625  	c->old_leb_cnt = c->leb_cnt;
626  	if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
627  		c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
628  		if (c->ro_mount)
629  			dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
630  				c->old_leb_cnt,	c->leb_cnt);
631  		else {
632  			dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
633  				c->old_leb_cnt, c->leb_cnt);
634  			sup->leb_cnt = cpu_to_le32(c->leb_cnt);
635  			err = ubifs_write_sb_node(c, sup);
636  			if (err)
637  				goto out;
638  			c->old_leb_cnt = c->leb_cnt;
639  		}
640  	}
641  
642  	c->log_bytes = (long long)c->log_lebs * c->leb_size;
643  	c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
644  	c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
645  	c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
646  	c->orph_first = c->lpt_last + 1;
647  	c->orph_last = c->orph_first + c->orph_lebs - 1;
648  	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
649  	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
650  	c->main_first = c->leb_cnt - c->main_lebs;
651  
652  	err = validate_sb(c, sup);
653  out:
654  	kfree(sup);
655  	return err;
656  }
657  
658  /**
659   * fixup_leb - fixup/unmap an LEB containing free space.
660   * @c: UBIFS file-system description object
661   * @lnum: the LEB number to fix up
662   * @len: number of used bytes in LEB (starting at offset 0)
663   *
664   * This function reads the contents of the given LEB number @lnum, then fixes
665   * it up, so that empty min. I/O units in the end of LEB are actually erased on
666   * flash (rather than being just all-0xff real data). If the LEB is completely
667   * empty, it is simply unmapped.
668   */
669  static int fixup_leb(struct ubifs_info *c, int lnum, int len)
670  {
671  	int err;
672  
673  	ubifs_assert(len >= 0);
674  	ubifs_assert(len % c->min_io_size == 0);
675  	ubifs_assert(len < c->leb_size);
676  
677  	if (len == 0) {
678  		dbg_mnt("unmap empty LEB %d", lnum);
679  		return ubifs_leb_unmap(c, lnum);
680  	}
681  
682  	dbg_mnt("fixup LEB %d, data len %d", lnum, len);
683  	err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
684  	if (err)
685  		return err;
686  
687  	return ubifs_leb_change(c, lnum, c->sbuf, len);
688  }
689  
690  /**
691   * fixup_free_space - find & remap all LEBs containing free space.
692   * @c: UBIFS file-system description object
693   *
694   * This function walks through all LEBs in the filesystem and fiexes up those
695   * containing free/empty space.
696   */
697  static int fixup_free_space(struct ubifs_info *c)
698  {
699  	int lnum, err = 0;
700  	struct ubifs_lprops *lprops;
701  
702  	ubifs_get_lprops(c);
703  
704  	/* Fixup LEBs in the master area */
705  	for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
706  		err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
707  		if (err)
708  			goto out;
709  	}
710  
711  	/* Unmap unused log LEBs */
712  	lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
713  	while (lnum != c->ltail_lnum) {
714  		err = fixup_leb(c, lnum, 0);
715  		if (err)
716  			goto out;
717  		lnum = ubifs_next_log_lnum(c, lnum);
718  	}
719  
720  	/*
721  	 * Fixup the log head which contains the only a CS node at the
722  	 * beginning.
723  	 */
724  	err = fixup_leb(c, c->lhead_lnum,
725  			ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
726  	if (err)
727  		goto out;
728  
729  	/* Fixup LEBs in the LPT area */
730  	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
731  		int free = c->ltab[lnum - c->lpt_first].free;
732  
733  		if (free > 0) {
734  			err = fixup_leb(c, lnum, c->leb_size - free);
735  			if (err)
736  				goto out;
737  		}
738  	}
739  
740  	/* Unmap LEBs in the orphans area */
741  	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
742  		err = fixup_leb(c, lnum, 0);
743  		if (err)
744  			goto out;
745  	}
746  
747  	/* Fixup LEBs in the main area */
748  	for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
749  		lprops = ubifs_lpt_lookup(c, lnum);
750  		if (IS_ERR(lprops)) {
751  			err = PTR_ERR(lprops);
752  			goto out;
753  		}
754  
755  		if (lprops->free > 0) {
756  			err = fixup_leb(c, lnum, c->leb_size - lprops->free);
757  			if (err)
758  				goto out;
759  		}
760  	}
761  
762  out:
763  	ubifs_release_lprops(c);
764  	return err;
765  }
766  
767  /**
768   * ubifs_fixup_free_space - find & fix all LEBs with free space.
769   * @c: UBIFS file-system description object
770   *
771   * This function fixes up LEBs containing free space on first mount, if the
772   * appropriate flag was set when the FS was created. Each LEB with one or more
773   * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
774   * the free space is actually erased. E.g., this is necessary for some NAND
775   * chips, since the free space may have been programmed like real "0xff" data
776   * (generating a non-0xff ECC), causing future writes to the not-really-erased
777   * NAND pages to behave badly. After the space is fixed up, the superblock flag
778   * is cleared, so that this is skipped for all future mounts.
779   */
780  int ubifs_fixup_free_space(struct ubifs_info *c)
781  {
782  	int err;
783  	struct ubifs_sb_node *sup;
784  
785  	ubifs_assert(c->space_fixup);
786  	ubifs_assert(!c->ro_mount);
787  
788  	ubifs_msg(c, "start fixing up free space");
789  
790  	err = fixup_free_space(c);
791  	if (err)
792  		return err;
793  
794  	sup = ubifs_read_sb_node(c);
795  	if (IS_ERR(sup))
796  		return PTR_ERR(sup);
797  
798  	/* Free-space fixup is no longer required */
799  	c->space_fixup = 0;
800  	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
801  
802  	err = ubifs_write_sb_node(c, sup);
803  	kfree(sup);
804  	if (err)
805  		return err;
806  
807  	ubifs_msg(c, "free space fixup complete");
808  	return err;
809  }
810