xref: /openbmc/linux/drivers/mtd/ubi/vtbl.c (revision 81d67439)
1 /*
2  * Copyright (c) International Business Machines Corp., 2006
3  * Copyright (c) Nokia Corporation, 2006, 2007
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
13  * the GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  *
19  * Author: Artem Bityutskiy (Битюцкий Артём)
20  */
21 
22 /*
23  * This file includes volume table manipulation code. The volume table is an
24  * on-flash table containing volume meta-data like name, number of reserved
25  * physical eraseblocks, type, etc. The volume table is stored in the so-called
26  * "layout volume".
27  *
28  * The layout volume is an internal volume which is organized as follows. It
29  * consists of two logical eraseblocks - LEB 0 and LEB 1. Each logical
30  * eraseblock stores one volume table copy, i.e. LEB 0 and LEB 1 duplicate each
31  * other. This redundancy guarantees robustness to unclean reboots. The volume
32  * table is basically an array of volume table records. Each record contains
33  * full information about the volume and protected by a CRC checksum.
34  *
35  * The volume table is changed, it is first changed in RAM. Then LEB 0 is
36  * erased, and the updated volume table is written back to LEB 0. Then same for
37  * LEB 1. This scheme guarantees recoverability from unclean reboots.
38  *
39  * In this UBI implementation the on-flash volume table does not contain any
40  * information about how many data static volumes contain. This information may
41  * be found from the scanning data.
42  *
43  * But it would still be beneficial to store this information in the volume
44  * table. For example, suppose we have a static volume X, and all its physical
45  * eraseblocks became bad for some reasons. Suppose we are attaching the
46  * corresponding MTD device, the scanning has found no logical eraseblocks
47  * corresponding to the volume X. According to the volume table volume X does
48  * exist. So we don't know whether it is just empty or all its physical
49  * eraseblocks went bad. So we cannot alarm the user about this corruption.
50  *
51  * The volume table also stores so-called "update marker", which is used for
52  * volume updates. Before updating the volume, the update marker is set, and
53  * after the update operation is finished, the update marker is cleared. So if
54  * the update operation was interrupted (e.g. by an unclean reboot) - the
55  * update marker is still there and we know that the volume's contents is
56  * damaged.
57  */
58 
59 #include <linux/crc32.h>
60 #include <linux/err.h>
61 #include <linux/slab.h>
62 #include <asm/div64.h>
63 #include "ubi.h"
64 
65 #ifdef CONFIG_MTD_UBI_DEBUG
66 static void paranoid_vtbl_check(const struct ubi_device *ubi);
67 #else
68 #define paranoid_vtbl_check(ubi)
69 #endif
70 
71 /* Empty volume table record */
72 static struct ubi_vtbl_record empty_vtbl_record;
73 
74 /**
75  * ubi_change_vtbl_record - change volume table record.
76  * @ubi: UBI device description object
77  * @idx: table index to change
78  * @vtbl_rec: new volume table record
79  *
80  * This function changes volume table record @idx. If @vtbl_rec is %NULL, empty
81  * volume table record is written. The caller does not have to calculate CRC of
82  * the record as it is done by this function. Returns zero in case of success
83  * and a negative error code in case of failure.
84  */
85 int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
86 			   struct ubi_vtbl_record *vtbl_rec)
87 {
88 	int i, err;
89 	uint32_t crc;
90 	struct ubi_volume *layout_vol;
91 
92 	ubi_assert(idx >= 0 && idx < ubi->vtbl_slots);
93 	layout_vol = ubi->volumes[vol_id2idx(ubi, UBI_LAYOUT_VOLUME_ID)];
94 
95 	if (!vtbl_rec)
96 		vtbl_rec = &empty_vtbl_record;
97 	else {
98 		crc = crc32(UBI_CRC32_INIT, vtbl_rec, UBI_VTBL_RECORD_SIZE_CRC);
99 		vtbl_rec->crc = cpu_to_be32(crc);
100 	}
101 
102 	memcpy(&ubi->vtbl[idx], vtbl_rec, sizeof(struct ubi_vtbl_record));
103 	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
104 		err = ubi_eba_unmap_leb(ubi, layout_vol, i);
105 		if (err)
106 			return err;
107 
108 		err = ubi_eba_write_leb(ubi, layout_vol, i, ubi->vtbl, 0,
109 					ubi->vtbl_size, UBI_LONGTERM);
110 		if (err)
111 			return err;
112 	}
113 
114 	paranoid_vtbl_check(ubi);
115 	return 0;
116 }
117 
118 /**
119  * ubi_vtbl_rename_volumes - rename UBI volumes in the volume table.
120  * @ubi: UBI device description object
121  * @rename_list: list of &struct ubi_rename_entry objects
122  *
123  * This function re-names multiple volumes specified in @req in the volume
124  * table. Returns zero in case of success and a negative error code in case of
125  * failure.
126  */
127 int ubi_vtbl_rename_volumes(struct ubi_device *ubi,
128 			    struct list_head *rename_list)
129 {
130 	int i, err;
131 	struct ubi_rename_entry *re;
132 	struct ubi_volume *layout_vol;
133 
134 	list_for_each_entry(re, rename_list, list) {
135 		uint32_t crc;
136 		struct ubi_volume *vol = re->desc->vol;
137 		struct ubi_vtbl_record *vtbl_rec = &ubi->vtbl[vol->vol_id];
138 
139 		if (re->remove) {
140 			memcpy(vtbl_rec, &empty_vtbl_record,
141 			       sizeof(struct ubi_vtbl_record));
142 			continue;
143 		}
144 
145 		vtbl_rec->name_len = cpu_to_be16(re->new_name_len);
146 		memcpy(vtbl_rec->name, re->new_name, re->new_name_len);
147 		memset(vtbl_rec->name + re->new_name_len, 0,
148 		       UBI_VOL_NAME_MAX + 1 - re->new_name_len);
149 		crc = crc32(UBI_CRC32_INIT, vtbl_rec,
150 			    UBI_VTBL_RECORD_SIZE_CRC);
151 		vtbl_rec->crc = cpu_to_be32(crc);
152 	}
153 
154 	layout_vol = ubi->volumes[vol_id2idx(ubi, UBI_LAYOUT_VOLUME_ID)];
155 	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
156 		err = ubi_eba_unmap_leb(ubi, layout_vol, i);
157 		if (err)
158 			return err;
159 
160 		err = ubi_eba_write_leb(ubi, layout_vol, i, ubi->vtbl, 0,
161 					ubi->vtbl_size, UBI_LONGTERM);
162 		if (err)
163 			return err;
164 	}
165 
166 	return 0;
167 }
168 
169 /**
170  * vtbl_check - check if volume table is not corrupted and sensible.
171  * @ubi: UBI device description object
172  * @vtbl: volume table
173  *
174  * This function returns zero if @vtbl is all right, %1 if CRC is incorrect,
175  * and %-EINVAL if it contains inconsistent data.
176  */
177 static int vtbl_check(const struct ubi_device *ubi,
178 		      const struct ubi_vtbl_record *vtbl)
179 {
180 	int i, n, reserved_pebs, alignment, data_pad, vol_type, name_len;
181 	int upd_marker, err;
182 	uint32_t crc;
183 	const char *name;
184 
185 	for (i = 0; i < ubi->vtbl_slots; i++) {
186 		cond_resched();
187 
188 		reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
189 		alignment = be32_to_cpu(vtbl[i].alignment);
190 		data_pad = be32_to_cpu(vtbl[i].data_pad);
191 		upd_marker = vtbl[i].upd_marker;
192 		vol_type = vtbl[i].vol_type;
193 		name_len = be16_to_cpu(vtbl[i].name_len);
194 		name = &vtbl[i].name[0];
195 
196 		crc = crc32(UBI_CRC32_INIT, &vtbl[i], UBI_VTBL_RECORD_SIZE_CRC);
197 		if (be32_to_cpu(vtbl[i].crc) != crc) {
198 			ubi_err("bad CRC at record %u: %#08x, not %#08x",
199 				 i, crc, be32_to_cpu(vtbl[i].crc));
200 			ubi_dbg_dump_vtbl_record(&vtbl[i], i);
201 			return 1;
202 		}
203 
204 		if (reserved_pebs == 0) {
205 			if (memcmp(&vtbl[i], &empty_vtbl_record,
206 						UBI_VTBL_RECORD_SIZE)) {
207 				err = 2;
208 				goto bad;
209 			}
210 			continue;
211 		}
212 
213 		if (reserved_pebs < 0 || alignment < 0 || data_pad < 0 ||
214 		    name_len < 0) {
215 			err = 3;
216 			goto bad;
217 		}
218 
219 		if (alignment > ubi->leb_size || alignment == 0) {
220 			err = 4;
221 			goto bad;
222 		}
223 
224 		n = alignment & (ubi->min_io_size - 1);
225 		if (alignment != 1 && n) {
226 			err = 5;
227 			goto bad;
228 		}
229 
230 		n = ubi->leb_size % alignment;
231 		if (data_pad != n) {
232 			dbg_err("bad data_pad, has to be %d", n);
233 			err = 6;
234 			goto bad;
235 		}
236 
237 		if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
238 			err = 7;
239 			goto bad;
240 		}
241 
242 		if (upd_marker != 0 && upd_marker != 1) {
243 			err = 8;
244 			goto bad;
245 		}
246 
247 		if (reserved_pebs > ubi->good_peb_count) {
248 			dbg_err("too large reserved_pebs %d, good PEBs %d",
249 				reserved_pebs, ubi->good_peb_count);
250 			err = 9;
251 			goto bad;
252 		}
253 
254 		if (name_len > UBI_VOL_NAME_MAX) {
255 			err = 10;
256 			goto bad;
257 		}
258 
259 		if (name[0] == '\0') {
260 			err = 11;
261 			goto bad;
262 		}
263 
264 		if (name_len != strnlen(name, name_len + 1)) {
265 			err = 12;
266 			goto bad;
267 		}
268 	}
269 
270 	/* Checks that all names are unique */
271 	for (i = 0; i < ubi->vtbl_slots - 1; i++) {
272 		for (n = i + 1; n < ubi->vtbl_slots; n++) {
273 			int len1 = be16_to_cpu(vtbl[i].name_len);
274 			int len2 = be16_to_cpu(vtbl[n].name_len);
275 
276 			if (len1 > 0 && len1 == len2 &&
277 			    !strncmp(vtbl[i].name, vtbl[n].name, len1)) {
278 				ubi_err("volumes %d and %d have the same name"
279 					" \"%s\"", i, n, vtbl[i].name);
280 				ubi_dbg_dump_vtbl_record(&vtbl[i], i);
281 				ubi_dbg_dump_vtbl_record(&vtbl[n], n);
282 				return -EINVAL;
283 			}
284 		}
285 	}
286 
287 	return 0;
288 
289 bad:
290 	ubi_err("volume table check failed: record %d, error %d", i, err);
291 	ubi_dbg_dump_vtbl_record(&vtbl[i], i);
292 	return -EINVAL;
293 }
294 
295 /**
296  * create_vtbl - create a copy of volume table.
297  * @ubi: UBI device description object
298  * @si: scanning information
299  * @copy: number of the volume table copy
300  * @vtbl: contents of the volume table
301  *
302  * This function returns zero in case of success and a negative error code in
303  * case of failure.
304  */
305 static int create_vtbl(struct ubi_device *ubi, struct ubi_scan_info *si,
306 		       int copy, void *vtbl)
307 {
308 	int err, tries = 0;
309 	static struct ubi_vid_hdr *vid_hdr;
310 	struct ubi_scan_leb *new_seb;
311 
312 	ubi_msg("create volume table (copy #%d)", copy + 1);
313 
314 	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
315 	if (!vid_hdr)
316 		return -ENOMEM;
317 
318 retry:
319 	new_seb = ubi_scan_get_free_peb(ubi, si);
320 	if (IS_ERR(new_seb)) {
321 		err = PTR_ERR(new_seb);
322 		goto out_free;
323 	}
324 
325 	vid_hdr->vol_type = UBI_VID_DYNAMIC;
326 	vid_hdr->vol_id = cpu_to_be32(UBI_LAYOUT_VOLUME_ID);
327 	vid_hdr->compat = UBI_LAYOUT_VOLUME_COMPAT;
328 	vid_hdr->data_size = vid_hdr->used_ebs =
329 			     vid_hdr->data_pad = cpu_to_be32(0);
330 	vid_hdr->lnum = cpu_to_be32(copy);
331 	vid_hdr->sqnum = cpu_to_be64(++si->max_sqnum);
332 
333 	/* The EC header is already there, write the VID header */
334 	err = ubi_io_write_vid_hdr(ubi, new_seb->pnum, vid_hdr);
335 	if (err)
336 		goto write_error;
337 
338 	/* Write the layout volume contents */
339 	err = ubi_io_write_data(ubi, vtbl, new_seb->pnum, 0, ubi->vtbl_size);
340 	if (err)
341 		goto write_error;
342 
343 	/*
344 	 * And add it to the scanning information. Don't delete the old version
345 	 * of this LEB as it will be deleted and freed in 'ubi_scan_add_used()'.
346 	 */
347 	err = ubi_scan_add_used(ubi, si, new_seb->pnum, new_seb->ec,
348 				vid_hdr, 0);
349 	kfree(new_seb);
350 	ubi_free_vid_hdr(ubi, vid_hdr);
351 	return err;
352 
353 write_error:
354 	if (err == -EIO && ++tries <= 5) {
355 		/*
356 		 * Probably this physical eraseblock went bad, try to pick
357 		 * another one.
358 		 */
359 		list_add(&new_seb->u.list, &si->erase);
360 		goto retry;
361 	}
362 	kfree(new_seb);
363 out_free:
364 	ubi_free_vid_hdr(ubi, vid_hdr);
365 	return err;
366 
367 }
368 
369 /**
370  * process_lvol - process the layout volume.
371  * @ubi: UBI device description object
372  * @si: scanning information
373  * @sv: layout volume scanning information
374  *
375  * This function is responsible for reading the layout volume, ensuring it is
376  * not corrupted, and recovering from corruptions if needed. Returns volume
377  * table in case of success and a negative error code in case of failure.
378  */
379 static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
380 					    struct ubi_scan_info *si,
381 					    struct ubi_scan_volume *sv)
382 {
383 	int err;
384 	struct rb_node *rb;
385 	struct ubi_scan_leb *seb;
386 	struct ubi_vtbl_record *leb[UBI_LAYOUT_VOLUME_EBS] = { NULL, NULL };
387 	int leb_corrupted[UBI_LAYOUT_VOLUME_EBS] = {1, 1};
388 
389 	/*
390 	 * UBI goes through the following steps when it changes the layout
391 	 * volume:
392 	 * a. erase LEB 0;
393 	 * b. write new data to LEB 0;
394 	 * c. erase LEB 1;
395 	 * d. write new data to LEB 1.
396 	 *
397 	 * Before the change, both LEBs contain the same data.
398 	 *
399 	 * Due to unclean reboots, the contents of LEB 0 may be lost, but there
400 	 * should LEB 1. So it is OK if LEB 0 is corrupted while LEB 1 is not.
401 	 * Similarly, LEB 1 may be lost, but there should be LEB 0. And
402 	 * finally, unclean reboots may result in a situation when neither LEB
403 	 * 0 nor LEB 1 are corrupted, but they are different. In this case, LEB
404 	 * 0 contains more recent information.
405 	 *
406 	 * So the plan is to first check LEB 0. Then
407 	 * a. if LEB 0 is OK, it must be containing the most recent data; then
408 	 *    we compare it with LEB 1, and if they are different, we copy LEB
409 	 *    0 to LEB 1;
410 	 * b. if LEB 0 is corrupted, but LEB 1 has to be OK, and we copy LEB 1
411 	 *    to LEB 0.
412 	 */
413 
414 	dbg_gen("check layout volume");
415 
416 	/* Read both LEB 0 and LEB 1 into memory */
417 	ubi_rb_for_each_entry(rb, seb, &sv->root, u.rb) {
418 		leb[seb->lnum] = vzalloc(ubi->vtbl_size);
419 		if (!leb[seb->lnum]) {
420 			err = -ENOMEM;
421 			goto out_free;
422 		}
423 
424 		err = ubi_io_read_data(ubi, leb[seb->lnum], seb->pnum, 0,
425 				       ubi->vtbl_size);
426 		if (err == UBI_IO_BITFLIPS || err == -EBADMSG)
427 			/*
428 			 * Scrub the PEB later. Note, -EBADMSG indicates an
429 			 * uncorrectable ECC error, but we have our own CRC and
430 			 * the data will be checked later. If the data is OK,
431 			 * the PEB will be scrubbed (because we set
432 			 * seb->scrub). If the data is not OK, the contents of
433 			 * the PEB will be recovered from the second copy, and
434 			 * seb->scrub will be cleared in
435 			 * 'ubi_scan_add_used()'.
436 			 */
437 			seb->scrub = 1;
438 		else if (err)
439 			goto out_free;
440 	}
441 
442 	err = -EINVAL;
443 	if (leb[0]) {
444 		leb_corrupted[0] = vtbl_check(ubi, leb[0]);
445 		if (leb_corrupted[0] < 0)
446 			goto out_free;
447 	}
448 
449 	if (!leb_corrupted[0]) {
450 		/* LEB 0 is OK */
451 		if (leb[1])
452 			leb_corrupted[1] = memcmp(leb[0], leb[1],
453 						  ubi->vtbl_size);
454 		if (leb_corrupted[1]) {
455 			ubi_warn("volume table copy #2 is corrupted");
456 			err = create_vtbl(ubi, si, 1, leb[0]);
457 			if (err)
458 				goto out_free;
459 			ubi_msg("volume table was restored");
460 		}
461 
462 		/* Both LEB 1 and LEB 2 are OK and consistent */
463 		vfree(leb[1]);
464 		return leb[0];
465 	} else {
466 		/* LEB 0 is corrupted or does not exist */
467 		if (leb[1]) {
468 			leb_corrupted[1] = vtbl_check(ubi, leb[1]);
469 			if (leb_corrupted[1] < 0)
470 				goto out_free;
471 		}
472 		if (leb_corrupted[1]) {
473 			/* Both LEB 0 and LEB 1 are corrupted */
474 			ubi_err("both volume tables are corrupted");
475 			goto out_free;
476 		}
477 
478 		ubi_warn("volume table copy #1 is corrupted");
479 		err = create_vtbl(ubi, si, 0, leb[1]);
480 		if (err)
481 			goto out_free;
482 		ubi_msg("volume table was restored");
483 
484 		vfree(leb[0]);
485 		return leb[1];
486 	}
487 
488 out_free:
489 	vfree(leb[0]);
490 	vfree(leb[1]);
491 	return ERR_PTR(err);
492 }
493 
494 /**
495  * create_empty_lvol - create empty layout volume.
496  * @ubi: UBI device description object
497  * @si: scanning information
498  *
499  * This function returns volume table contents in case of success and a
500  * negative error code in case of failure.
501  */
502 static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi,
503 						 struct ubi_scan_info *si)
504 {
505 	int i;
506 	struct ubi_vtbl_record *vtbl;
507 
508 	vtbl = vzalloc(ubi->vtbl_size);
509 	if (!vtbl)
510 		return ERR_PTR(-ENOMEM);
511 
512 	for (i = 0; i < ubi->vtbl_slots; i++)
513 		memcpy(&vtbl[i], &empty_vtbl_record, UBI_VTBL_RECORD_SIZE);
514 
515 	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
516 		int err;
517 
518 		err = create_vtbl(ubi, si, i, vtbl);
519 		if (err) {
520 			vfree(vtbl);
521 			return ERR_PTR(err);
522 		}
523 	}
524 
525 	return vtbl;
526 }
527 
528 /**
529  * init_volumes - initialize volume information for existing volumes.
530  * @ubi: UBI device description object
531  * @si: scanning information
532  * @vtbl: volume table
533  *
534  * This function allocates volume description objects for existing volumes.
535  * Returns zero in case of success and a negative error code in case of
536  * failure.
537  */
538 static int init_volumes(struct ubi_device *ubi, const struct ubi_scan_info *si,
539 			const struct ubi_vtbl_record *vtbl)
540 {
541 	int i, reserved_pebs = 0;
542 	struct ubi_scan_volume *sv;
543 	struct ubi_volume *vol;
544 
545 	for (i = 0; i < ubi->vtbl_slots; i++) {
546 		cond_resched();
547 
548 		if (be32_to_cpu(vtbl[i].reserved_pebs) == 0)
549 			continue; /* Empty record */
550 
551 		vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
552 		if (!vol)
553 			return -ENOMEM;
554 
555 		vol->reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
556 		vol->alignment = be32_to_cpu(vtbl[i].alignment);
557 		vol->data_pad = be32_to_cpu(vtbl[i].data_pad);
558 		vol->upd_marker = vtbl[i].upd_marker;
559 		vol->vol_type = vtbl[i].vol_type == UBI_VID_DYNAMIC ?
560 					UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
561 		vol->name_len = be16_to_cpu(vtbl[i].name_len);
562 		vol->usable_leb_size = ubi->leb_size - vol->data_pad;
563 		memcpy(vol->name, vtbl[i].name, vol->name_len);
564 		vol->name[vol->name_len] = '\0';
565 		vol->vol_id = i;
566 
567 		if (vtbl[i].flags & UBI_VTBL_AUTORESIZE_FLG) {
568 			/* Auto re-size flag may be set only for one volume */
569 			if (ubi->autoresize_vol_id != -1) {
570 				ubi_err("more than one auto-resize volume (%d "
571 					"and %d)", ubi->autoresize_vol_id, i);
572 				kfree(vol);
573 				return -EINVAL;
574 			}
575 
576 			ubi->autoresize_vol_id = i;
577 		}
578 
579 		ubi_assert(!ubi->volumes[i]);
580 		ubi->volumes[i] = vol;
581 		ubi->vol_count += 1;
582 		vol->ubi = ubi;
583 		reserved_pebs += vol->reserved_pebs;
584 
585 		/*
586 		 * In case of dynamic volume UBI knows nothing about how many
587 		 * data is stored there. So assume the whole volume is used.
588 		 */
589 		if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
590 			vol->used_ebs = vol->reserved_pebs;
591 			vol->last_eb_bytes = vol->usable_leb_size;
592 			vol->used_bytes =
593 				(long long)vol->used_ebs * vol->usable_leb_size;
594 			continue;
595 		}
596 
597 		/* Static volumes only */
598 		sv = ubi_scan_find_sv(si, i);
599 		if (!sv) {
600 			/*
601 			 * No eraseblocks belonging to this volume found. We
602 			 * don't actually know whether this static volume is
603 			 * completely corrupted or just contains no data. And
604 			 * we cannot know this as long as data size is not
605 			 * stored on flash. So we just assume the volume is
606 			 * empty. FIXME: this should be handled.
607 			 */
608 			continue;
609 		}
610 
611 		if (sv->leb_count != sv->used_ebs) {
612 			/*
613 			 * We found a static volume which misses several
614 			 * eraseblocks. Treat it as corrupted.
615 			 */
616 			ubi_warn("static volume %d misses %d LEBs - corrupted",
617 				 sv->vol_id, sv->used_ebs - sv->leb_count);
618 			vol->corrupted = 1;
619 			continue;
620 		}
621 
622 		vol->used_ebs = sv->used_ebs;
623 		vol->used_bytes =
624 			(long long)(vol->used_ebs - 1) * vol->usable_leb_size;
625 		vol->used_bytes += sv->last_data_size;
626 		vol->last_eb_bytes = sv->last_data_size;
627 	}
628 
629 	/* And add the layout volume */
630 	vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
631 	if (!vol)
632 		return -ENOMEM;
633 
634 	vol->reserved_pebs = UBI_LAYOUT_VOLUME_EBS;
635 	vol->alignment = 1;
636 	vol->vol_type = UBI_DYNAMIC_VOLUME;
637 	vol->name_len = sizeof(UBI_LAYOUT_VOLUME_NAME) - 1;
638 	memcpy(vol->name, UBI_LAYOUT_VOLUME_NAME, vol->name_len + 1);
639 	vol->usable_leb_size = ubi->leb_size;
640 	vol->used_ebs = vol->reserved_pebs;
641 	vol->last_eb_bytes = vol->reserved_pebs;
642 	vol->used_bytes =
643 		(long long)vol->used_ebs * (ubi->leb_size - vol->data_pad);
644 	vol->vol_id = UBI_LAYOUT_VOLUME_ID;
645 	vol->ref_count = 1;
646 
647 	ubi_assert(!ubi->volumes[i]);
648 	ubi->volumes[vol_id2idx(ubi, vol->vol_id)] = vol;
649 	reserved_pebs += vol->reserved_pebs;
650 	ubi->vol_count += 1;
651 	vol->ubi = ubi;
652 
653 	if (reserved_pebs > ubi->avail_pebs) {
654 		ubi_err("not enough PEBs, required %d, available %d",
655 			reserved_pebs, ubi->avail_pebs);
656 		if (ubi->corr_peb_count)
657 			ubi_err("%d PEBs are corrupted and not used",
658 				ubi->corr_peb_count);
659 	}
660 	ubi->rsvd_pebs += reserved_pebs;
661 	ubi->avail_pebs -= reserved_pebs;
662 
663 	return 0;
664 }
665 
666 /**
667  * check_sv - check volume scanning information.
668  * @vol: UBI volume description object
669  * @sv: volume scanning information
670  *
671  * This function returns zero if the volume scanning information is consistent
672  * to the data read from the volume tabla, and %-EINVAL if not.
673  */
674 static int check_sv(const struct ubi_volume *vol,
675 		    const struct ubi_scan_volume *sv)
676 {
677 	int err;
678 
679 	if (sv->highest_lnum >= vol->reserved_pebs) {
680 		err = 1;
681 		goto bad;
682 	}
683 	if (sv->leb_count > vol->reserved_pebs) {
684 		err = 2;
685 		goto bad;
686 	}
687 	if (sv->vol_type != vol->vol_type) {
688 		err = 3;
689 		goto bad;
690 	}
691 	if (sv->used_ebs > vol->reserved_pebs) {
692 		err = 4;
693 		goto bad;
694 	}
695 	if (sv->data_pad != vol->data_pad) {
696 		err = 5;
697 		goto bad;
698 	}
699 	return 0;
700 
701 bad:
702 	ubi_err("bad scanning information, error %d", err);
703 	ubi_dbg_dump_sv(sv);
704 	ubi_dbg_dump_vol_info(vol);
705 	return -EINVAL;
706 }
707 
708 /**
709  * check_scanning_info - check that scanning information.
710  * @ubi: UBI device description object
711  * @si: scanning information
712  *
713  * Even though we protect on-flash data by CRC checksums, we still don't trust
714  * the media. This function ensures that scanning information is consistent to
715  * the information read from the volume table. Returns zero if the scanning
716  * information is OK and %-EINVAL if it is not.
717  */
718 static int check_scanning_info(const struct ubi_device *ubi,
719 			       struct ubi_scan_info *si)
720 {
721 	int err, i;
722 	struct ubi_scan_volume *sv;
723 	struct ubi_volume *vol;
724 
725 	if (si->vols_found > UBI_INT_VOL_COUNT + ubi->vtbl_slots) {
726 		ubi_err("scanning found %d volumes, maximum is %d + %d",
727 			si->vols_found, UBI_INT_VOL_COUNT, ubi->vtbl_slots);
728 		return -EINVAL;
729 	}
730 
731 	if (si->highest_vol_id >= ubi->vtbl_slots + UBI_INT_VOL_COUNT &&
732 	    si->highest_vol_id < UBI_INTERNAL_VOL_START) {
733 		ubi_err("too large volume ID %d found by scanning",
734 			si->highest_vol_id);
735 		return -EINVAL;
736 	}
737 
738 	for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
739 		cond_resched();
740 
741 		sv = ubi_scan_find_sv(si, i);
742 		vol = ubi->volumes[i];
743 		if (!vol) {
744 			if (sv)
745 				ubi_scan_rm_volume(si, sv);
746 			continue;
747 		}
748 
749 		if (vol->reserved_pebs == 0) {
750 			ubi_assert(i < ubi->vtbl_slots);
751 
752 			if (!sv)
753 				continue;
754 
755 			/*
756 			 * During scanning we found a volume which does not
757 			 * exist according to the information in the volume
758 			 * table. This must have happened due to an unclean
759 			 * reboot while the volume was being removed. Discard
760 			 * these eraseblocks.
761 			 */
762 			ubi_msg("finish volume %d removal", sv->vol_id);
763 			ubi_scan_rm_volume(si, sv);
764 		} else if (sv) {
765 			err = check_sv(vol, sv);
766 			if (err)
767 				return err;
768 		}
769 	}
770 
771 	return 0;
772 }
773 
774 /**
775  * ubi_read_volume_table - read the volume table.
776  * @ubi: UBI device description object
777  * @si: scanning information
778  *
779  * This function reads volume table, checks it, recover from errors if needed,
780  * or creates it if needed. Returns zero in case of success and a negative
781  * error code in case of failure.
782  */
783 int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_scan_info *si)
784 {
785 	int i, err;
786 	struct ubi_scan_volume *sv;
787 
788 	empty_vtbl_record.crc = cpu_to_be32(0xf116c36b);
789 
790 	/*
791 	 * The number of supported volumes is limited by the eraseblock size
792 	 * and by the UBI_MAX_VOLUMES constant.
793 	 */
794 	ubi->vtbl_slots = ubi->leb_size / UBI_VTBL_RECORD_SIZE;
795 	if (ubi->vtbl_slots > UBI_MAX_VOLUMES)
796 		ubi->vtbl_slots = UBI_MAX_VOLUMES;
797 
798 	ubi->vtbl_size = ubi->vtbl_slots * UBI_VTBL_RECORD_SIZE;
799 	ubi->vtbl_size = ALIGN(ubi->vtbl_size, ubi->min_io_size);
800 
801 	sv = ubi_scan_find_sv(si, UBI_LAYOUT_VOLUME_ID);
802 	if (!sv) {
803 		/*
804 		 * No logical eraseblocks belonging to the layout volume were
805 		 * found. This could mean that the flash is just empty. In
806 		 * this case we create empty layout volume.
807 		 *
808 		 * But if flash is not empty this must be a corruption or the
809 		 * MTD device just contains garbage.
810 		 */
811 		if (si->is_empty) {
812 			ubi->vtbl = create_empty_lvol(ubi, si);
813 			if (IS_ERR(ubi->vtbl))
814 				return PTR_ERR(ubi->vtbl);
815 		} else {
816 			ubi_err("the layout volume was not found");
817 			return -EINVAL;
818 		}
819 	} else {
820 		if (sv->leb_count > UBI_LAYOUT_VOLUME_EBS) {
821 			/* This must not happen with proper UBI images */
822 			dbg_err("too many LEBs (%d) in layout volume",
823 				sv->leb_count);
824 			return -EINVAL;
825 		}
826 
827 		ubi->vtbl = process_lvol(ubi, si, sv);
828 		if (IS_ERR(ubi->vtbl))
829 			return PTR_ERR(ubi->vtbl);
830 	}
831 
832 	ubi->avail_pebs = ubi->good_peb_count - ubi->corr_peb_count;
833 
834 	/*
835 	 * The layout volume is OK, initialize the corresponding in-RAM data
836 	 * structures.
837 	 */
838 	err = init_volumes(ubi, si, ubi->vtbl);
839 	if (err)
840 		goto out_free;
841 
842 	/*
843 	 * Make sure that the scanning information is consistent to the
844 	 * information stored in the volume table.
845 	 */
846 	err = check_scanning_info(ubi, si);
847 	if (err)
848 		goto out_free;
849 
850 	return 0;
851 
852 out_free:
853 	vfree(ubi->vtbl);
854 	for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
855 		kfree(ubi->volumes[i]);
856 		ubi->volumes[i] = NULL;
857 	}
858 	return err;
859 }
860 
861 #ifdef CONFIG_MTD_UBI_DEBUG
862 
863 /**
864  * paranoid_vtbl_check - check volume table.
865  * @ubi: UBI device description object
866  */
867 static void paranoid_vtbl_check(const struct ubi_device *ubi)
868 {
869 	if (!ubi->dbg->chk_gen)
870 		return;
871 
872 	if (vtbl_check(ubi, ubi->vtbl)) {
873 		ubi_err("paranoid check failed");
874 		BUG();
875 	}
876 }
877 
878 #endif /* CONFIG_MTD_UBI_DEBUG */
879