xref: /openbmc/linux/drivers/mtd/ubi/kapi.c (revision 4800cd83)
1 /*
2  * Copyright (c) International Business Machines Corp., 2006
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
12  * the GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17  *
18  * Author: Artem Bityutskiy (Битюцкий Артём)
19  */
20 
21 /* This file mostly implements UBI kernel API functions */
22 
23 #include <linux/module.h>
24 #include <linux/err.h>
25 #include <linux/slab.h>
26 #include <linux/namei.h>
27 #include <linux/fs.h>
28 #include <asm/div64.h>
29 #include "ubi.h"
30 
31 /**
32  * ubi_do_get_device_info - get information about UBI device.
33  * @ubi: UBI device description object
34  * @di: the information is stored here
35  *
36  * This function is the same as 'ubi_get_device_info()', but it assumes the UBI
37  * device is locked and cannot disappear.
38  */
39 void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di)
40 {
41 	di->ubi_num = ubi->ubi_num;
42 	di->leb_size = ubi->leb_size;
43 	di->min_io_size = ubi->min_io_size;
44 	di->ro_mode = ubi->ro_mode;
45 	di->cdev = ubi->cdev.dev;
46 }
47 EXPORT_SYMBOL_GPL(ubi_do_get_device_info);
48 
49 /**
50  * ubi_get_device_info - get information about UBI device.
51  * @ubi_num: UBI device number
52  * @di: the information is stored here
53  *
54  * This function returns %0 in case of success, %-EINVAL if the UBI device
55  * number is invalid, and %-ENODEV if there is no such UBI device.
56  */
57 int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
58 {
59 	struct ubi_device *ubi;
60 
61 	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
62 		return -EINVAL;
63 	ubi = ubi_get_device(ubi_num);
64 	if (!ubi)
65 		return -ENODEV;
66 	ubi_do_get_device_info(ubi, di);
67 	ubi_put_device(ubi);
68 	return 0;
69 }
70 EXPORT_SYMBOL_GPL(ubi_get_device_info);
71 
72 /**
73  * ubi_do_get_volume_info - get information about UBI volume.
74  * @ubi: UBI device description object
75  * @vol: volume description object
76  * @vi: the information is stored here
77  */
78 void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
79 			    struct ubi_volume_info *vi)
80 {
81 	vi->vol_id = vol->vol_id;
82 	vi->ubi_num = ubi->ubi_num;
83 	vi->size = vol->reserved_pebs;
84 	vi->used_bytes = vol->used_bytes;
85 	vi->vol_type = vol->vol_type;
86 	vi->corrupted = vol->corrupted;
87 	vi->upd_marker = vol->upd_marker;
88 	vi->alignment = vol->alignment;
89 	vi->usable_leb_size = vol->usable_leb_size;
90 	vi->name_len = vol->name_len;
91 	vi->name = vol->name;
92 	vi->cdev = vol->cdev.dev;
93 }
94 
95 /**
96  * ubi_get_volume_info - get information about UBI volume.
97  * @desc: volume descriptor
98  * @vi: the information is stored here
99  */
100 void ubi_get_volume_info(struct ubi_volume_desc *desc,
101 			 struct ubi_volume_info *vi)
102 {
103 	ubi_do_get_volume_info(desc->vol->ubi, desc->vol, vi);
104 }
105 EXPORT_SYMBOL_GPL(ubi_get_volume_info);
106 
107 /**
108  * ubi_open_volume - open UBI volume.
109  * @ubi_num: UBI device number
110  * @vol_id: volume ID
111  * @mode: open mode
112  *
113  * The @mode parameter specifies if the volume should be opened in read-only
114  * mode, read-write mode, or exclusive mode. The exclusive mode guarantees that
115  * nobody else will be able to open this volume. UBI allows to have many volume
116  * readers and one writer at a time.
117  *
118  * If a static volume is being opened for the first time since boot, it will be
119  * checked by this function, which means it will be fully read and the CRC
120  * checksum of each logical eraseblock will be checked.
121  *
122  * This function returns volume descriptor in case of success and a negative
123  * error code in case of failure.
124  */
125 struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
126 {
127 	int err;
128 	struct ubi_volume_desc *desc;
129 	struct ubi_device *ubi;
130 	struct ubi_volume *vol;
131 
132 	dbg_gen("open device %d, volume %d, mode %d", ubi_num, vol_id, mode);
133 
134 	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
135 		return ERR_PTR(-EINVAL);
136 
137 	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
138 	    mode != UBI_EXCLUSIVE)
139 		return ERR_PTR(-EINVAL);
140 
141 	/*
142 	 * First of all, we have to get the UBI device to prevent its removal.
143 	 */
144 	ubi = ubi_get_device(ubi_num);
145 	if (!ubi)
146 		return ERR_PTR(-ENODEV);
147 
148 	if (vol_id < 0 || vol_id >= ubi->vtbl_slots) {
149 		err = -EINVAL;
150 		goto out_put_ubi;
151 	}
152 
153 	desc = kmalloc(sizeof(struct ubi_volume_desc), GFP_KERNEL);
154 	if (!desc) {
155 		err = -ENOMEM;
156 		goto out_put_ubi;
157 	}
158 
159 	err = -ENODEV;
160 	if (!try_module_get(THIS_MODULE))
161 		goto out_free;
162 
163 	spin_lock(&ubi->volumes_lock);
164 	vol = ubi->volumes[vol_id];
165 	if (!vol)
166 		goto out_unlock;
167 
168 	err = -EBUSY;
169 	switch (mode) {
170 	case UBI_READONLY:
171 		if (vol->exclusive)
172 			goto out_unlock;
173 		vol->readers += 1;
174 		break;
175 
176 	case UBI_READWRITE:
177 		if (vol->exclusive || vol->writers > 0)
178 			goto out_unlock;
179 		vol->writers += 1;
180 		break;
181 
182 	case UBI_EXCLUSIVE:
183 		if (vol->exclusive || vol->writers || vol->readers)
184 			goto out_unlock;
185 		vol->exclusive = 1;
186 		break;
187 	}
188 	get_device(&vol->dev);
189 	vol->ref_count += 1;
190 	spin_unlock(&ubi->volumes_lock);
191 
192 	desc->vol = vol;
193 	desc->mode = mode;
194 
195 	mutex_lock(&ubi->ckvol_mutex);
196 	if (!vol->checked) {
197 		/* This is the first open - check the volume */
198 		err = ubi_check_volume(ubi, vol_id);
199 		if (err < 0) {
200 			mutex_unlock(&ubi->ckvol_mutex);
201 			ubi_close_volume(desc);
202 			return ERR_PTR(err);
203 		}
204 		if (err == 1) {
205 			ubi_warn("volume %d on UBI device %d is corrupted",
206 				 vol_id, ubi->ubi_num);
207 			vol->corrupted = 1;
208 		}
209 		vol->checked = 1;
210 	}
211 	mutex_unlock(&ubi->ckvol_mutex);
212 
213 	return desc;
214 
215 out_unlock:
216 	spin_unlock(&ubi->volumes_lock);
217 	module_put(THIS_MODULE);
218 out_free:
219 	kfree(desc);
220 out_put_ubi:
221 	ubi_put_device(ubi);
222 	dbg_err("cannot open device %d, volume %d, error %d",
223 		ubi_num, vol_id, err);
224 	return ERR_PTR(err);
225 }
226 EXPORT_SYMBOL_GPL(ubi_open_volume);
227 
228 /**
229  * ubi_open_volume_nm - open UBI volume by name.
230  * @ubi_num: UBI device number
231  * @name: volume name
232  * @mode: open mode
233  *
234  * This function is similar to 'ubi_open_volume()', but opens a volume by name.
235  */
236 struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
237 					   int mode)
238 {
239 	int i, vol_id = -1, len;
240 	struct ubi_device *ubi;
241 	struct ubi_volume_desc *ret;
242 
243 	dbg_gen("open device %d, volume %s, mode %d", ubi_num, name, mode);
244 
245 	if (!name)
246 		return ERR_PTR(-EINVAL);
247 
248 	len = strnlen(name, UBI_VOL_NAME_MAX + 1);
249 	if (len > UBI_VOL_NAME_MAX)
250 		return ERR_PTR(-EINVAL);
251 
252 	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
253 		return ERR_PTR(-EINVAL);
254 
255 	ubi = ubi_get_device(ubi_num);
256 	if (!ubi)
257 		return ERR_PTR(-ENODEV);
258 
259 	spin_lock(&ubi->volumes_lock);
260 	/* Walk all volumes of this UBI device */
261 	for (i = 0; i < ubi->vtbl_slots; i++) {
262 		struct ubi_volume *vol = ubi->volumes[i];
263 
264 		if (vol && len == vol->name_len && !strcmp(name, vol->name)) {
265 			vol_id = i;
266 			break;
267 		}
268 	}
269 	spin_unlock(&ubi->volumes_lock);
270 
271 	if (vol_id >= 0)
272 		ret = ubi_open_volume(ubi_num, vol_id, mode);
273 	else
274 		ret = ERR_PTR(-ENODEV);
275 
276 	/*
277 	 * We should put the UBI device even in case of success, because
278 	 * 'ubi_open_volume()' took a reference as well.
279 	 */
280 	ubi_put_device(ubi);
281 	return ret;
282 }
283 EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
284 
285 /**
286  * ubi_open_volume_path - open UBI volume by its character device node path.
287  * @pathname: volume character device node path
288  * @mode: open mode
289  *
290  * This function is similar to 'ubi_open_volume()', but opens a volume the path
291  * to its character device node.
292  */
293 struct ubi_volume_desc *ubi_open_volume_path(const char *pathname, int mode)
294 {
295 	int error, ubi_num, vol_id, mod;
296 	struct inode *inode;
297 	struct path path;
298 
299 	dbg_gen("open volume %s, mode %d", pathname, mode);
300 
301 	if (!pathname || !*pathname)
302 		return ERR_PTR(-EINVAL);
303 
304 	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
305 	if (error)
306 		return ERR_PTR(error);
307 
308 	inode = path.dentry->d_inode;
309 	mod = inode->i_mode;
310 	ubi_num = ubi_major2num(imajor(inode));
311 	vol_id = iminor(inode) - 1;
312 	path_put(&path);
313 
314 	if (!S_ISCHR(mod))
315 		return ERR_PTR(-EINVAL);
316 	if (vol_id >= 0 && ubi_num >= 0)
317 		return ubi_open_volume(ubi_num, vol_id, mode);
318 	return ERR_PTR(-ENODEV);
319 }
320 EXPORT_SYMBOL_GPL(ubi_open_volume_path);
321 
322 /**
323  * ubi_close_volume - close UBI volume.
324  * @desc: volume descriptor
325  */
326 void ubi_close_volume(struct ubi_volume_desc *desc)
327 {
328 	struct ubi_volume *vol = desc->vol;
329 	struct ubi_device *ubi = vol->ubi;
330 
331 	dbg_gen("close device %d, volume %d, mode %d",
332 		ubi->ubi_num, vol->vol_id, desc->mode);
333 
334 	spin_lock(&ubi->volumes_lock);
335 	switch (desc->mode) {
336 	case UBI_READONLY:
337 		vol->readers -= 1;
338 		break;
339 	case UBI_READWRITE:
340 		vol->writers -= 1;
341 		break;
342 	case UBI_EXCLUSIVE:
343 		vol->exclusive = 0;
344 	}
345 	vol->ref_count -= 1;
346 	spin_unlock(&ubi->volumes_lock);
347 
348 	kfree(desc);
349 	put_device(&vol->dev);
350 	ubi_put_device(ubi);
351 	module_put(THIS_MODULE);
352 }
353 EXPORT_SYMBOL_GPL(ubi_close_volume);
354 
355 /**
356  * ubi_leb_read - read data.
357  * @desc: volume descriptor
358  * @lnum: logical eraseblock number to read from
359  * @buf: buffer where to store the read data
360  * @offset: offset within the logical eraseblock to read from
361  * @len: how many bytes to read
362  * @check: whether UBI has to check the read data's CRC or not.
363  *
364  * This function reads data from offset @offset of logical eraseblock @lnum and
365  * stores the data at @buf. When reading from static volumes, @check specifies
366  * whether the data has to be checked or not. If yes, the whole logical
367  * eraseblock will be read and its CRC checksum will be checked (i.e., the CRC
368  * checksum is per-eraseblock). So checking may substantially slow down the
369  * read speed. The @check argument is ignored for dynamic volumes.
370  *
371  * In case of success, this function returns zero. In case of failure, this
372  * function returns a negative error code.
373  *
374  * %-EBADMSG error code is returned:
375  * o for both static and dynamic volumes if MTD driver has detected a data
376  *   integrity problem (unrecoverable ECC checksum mismatch in case of NAND);
377  * o for static volumes in case of data CRC mismatch.
378  *
379  * If the volume is damaged because of an interrupted update this function just
380  * returns immediately with %-EBADF error code.
381  */
382 int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
383 		 int len, int check)
384 {
385 	struct ubi_volume *vol = desc->vol;
386 	struct ubi_device *ubi = vol->ubi;
387 	int err, vol_id = vol->vol_id;
388 
389 	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
390 
391 	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
392 	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
393 	    offset + len > vol->usable_leb_size)
394 		return -EINVAL;
395 
396 	if (vol->vol_type == UBI_STATIC_VOLUME) {
397 		if (vol->used_ebs == 0)
398 			/* Empty static UBI volume */
399 			return 0;
400 		if (lnum == vol->used_ebs - 1 &&
401 		    offset + len > vol->last_eb_bytes)
402 			return -EINVAL;
403 	}
404 
405 	if (vol->upd_marker)
406 		return -EBADF;
407 	if (len == 0)
408 		return 0;
409 
410 	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
411 	if (err && err == -EBADMSG && vol->vol_type == UBI_STATIC_VOLUME) {
412 		ubi_warn("mark volume %d as corrupted", vol_id);
413 		vol->corrupted = 1;
414 	}
415 
416 	return err;
417 }
418 EXPORT_SYMBOL_GPL(ubi_leb_read);
419 
420 /**
421  * ubi_leb_write - write data.
422  * @desc: volume descriptor
423  * @lnum: logical eraseblock number to write to
424  * @buf: data to write
425  * @offset: offset within the logical eraseblock where to write
426  * @len: how many bytes to write
427  * @dtype: expected data type
428  *
429  * This function writes @len bytes of data from @buf to offset @offset of
430  * logical eraseblock @lnum. The @dtype argument describes expected lifetime of
431  * the data.
432  *
433  * This function takes care of physical eraseblock write failures. If write to
434  * the physical eraseblock write operation fails, the logical eraseblock is
435  * re-mapped to another physical eraseblock, the data is recovered, and the
436  * write finishes. UBI has a pool of reserved physical eraseblocks for this.
437  *
438  * If all the data were successfully written, zero is returned. If an error
439  * occurred and UBI has not been able to recover from it, this function returns
440  * a negative error code. Note, in case of an error, it is possible that
441  * something was still written to the flash media, but that may be some
442  * garbage.
443  *
444  * If the volume is damaged because of an interrupted update this function just
445  * returns immediately with %-EBADF code.
446  */
447 int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
448 		  int offset, int len, int dtype)
449 {
450 	struct ubi_volume *vol = desc->vol;
451 	struct ubi_device *ubi = vol->ubi;
452 	int vol_id = vol->vol_id;
453 
454 	dbg_gen("write %d bytes to LEB %d:%d:%d", len, vol_id, lnum, offset);
455 
456 	if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
457 		return -EINVAL;
458 
459 	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
460 		return -EROFS;
461 
462 	if (lnum < 0 || lnum >= vol->reserved_pebs || offset < 0 || len < 0 ||
463 	    offset + len > vol->usable_leb_size ||
464 	    offset & (ubi->min_io_size - 1) || len & (ubi->min_io_size - 1))
465 		return -EINVAL;
466 
467 	if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
468 	    dtype != UBI_UNKNOWN)
469 		return -EINVAL;
470 
471 	if (vol->upd_marker)
472 		return -EBADF;
473 
474 	if (len == 0)
475 		return 0;
476 
477 	return ubi_eba_write_leb(ubi, vol, lnum, buf, offset, len, dtype);
478 }
479 EXPORT_SYMBOL_GPL(ubi_leb_write);
480 
481 /*
482  * ubi_leb_change - change logical eraseblock atomically.
483  * @desc: volume descriptor
484  * @lnum: logical eraseblock number to change
485  * @buf: data to write
486  * @len: how many bytes to write
487  * @dtype: expected data type
488  *
489  * This function changes the contents of a logical eraseblock atomically. @buf
490  * has to contain new logical eraseblock data, and @len - the length of the
491  * data, which has to be aligned. The length may be shorter than the logical
492  * eraseblock size, ant the logical eraseblock may be appended to more times
493  * later on. This function guarantees that in case of an unclean reboot the old
494  * contents is preserved. Returns zero in case of success and a negative error
495  * code in case of failure.
496  */
497 int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
498 		   int len, int dtype)
499 {
500 	struct ubi_volume *vol = desc->vol;
501 	struct ubi_device *ubi = vol->ubi;
502 	int vol_id = vol->vol_id;
503 
504 	dbg_gen("atomically write %d bytes to LEB %d:%d", len, vol_id, lnum);
505 
506 	if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
507 		return -EINVAL;
508 
509 	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
510 		return -EROFS;
511 
512 	if (lnum < 0 || lnum >= vol->reserved_pebs || len < 0 ||
513 	    len > vol->usable_leb_size || len & (ubi->min_io_size - 1))
514 		return -EINVAL;
515 
516 	if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
517 	    dtype != UBI_UNKNOWN)
518 		return -EINVAL;
519 
520 	if (vol->upd_marker)
521 		return -EBADF;
522 
523 	if (len == 0)
524 		return 0;
525 
526 	return ubi_eba_atomic_leb_change(ubi, vol, lnum, buf, len, dtype);
527 }
528 EXPORT_SYMBOL_GPL(ubi_leb_change);
529 
530 /**
531  * ubi_leb_erase - erase logical eraseblock.
532  * @desc: volume descriptor
533  * @lnum: logical eraseblock number
534  *
535  * This function un-maps logical eraseblock @lnum and synchronously erases the
536  * correspondent physical eraseblock. Returns zero in case of success and a
537  * negative error code in case of failure.
538  *
539  * If the volume is damaged because of an interrupted update this function just
540  * returns immediately with %-EBADF code.
541  */
542 int ubi_leb_erase(struct ubi_volume_desc *desc, int lnum)
543 {
544 	struct ubi_volume *vol = desc->vol;
545 	struct ubi_device *ubi = vol->ubi;
546 	int err;
547 
548 	dbg_gen("erase LEB %d:%d", vol->vol_id, lnum);
549 
550 	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
551 		return -EROFS;
552 
553 	if (lnum < 0 || lnum >= vol->reserved_pebs)
554 		return -EINVAL;
555 
556 	if (vol->upd_marker)
557 		return -EBADF;
558 
559 	err = ubi_eba_unmap_leb(ubi, vol, lnum);
560 	if (err)
561 		return err;
562 
563 	return ubi_wl_flush(ubi);
564 }
565 EXPORT_SYMBOL_GPL(ubi_leb_erase);
566 
567 /**
568  * ubi_leb_unmap - un-map logical eraseblock.
569  * @desc: volume descriptor
570  * @lnum: logical eraseblock number
571  *
572  * This function un-maps logical eraseblock @lnum and schedules the
573  * corresponding physical eraseblock for erasure, so that it will eventually be
574  * physically erased in background. This operation is much faster than the
575  * erase operation.
576  *
577  * Unlike erase, the un-map operation does not guarantee that the logical
578  * eraseblock will contain all 0xFF bytes when UBI is initialized again. For
579  * example, if several logical eraseblocks are un-mapped, and an unclean reboot
580  * happens after this, the logical eraseblocks will not necessarily be
581  * un-mapped again when this MTD device is attached. They may actually be
582  * mapped to the same physical eraseblocks again. So, this function has to be
583  * used with care.
584  *
585  * In other words, when un-mapping a logical eraseblock, UBI does not store
586  * any information about this on the flash media, it just marks the logical
587  * eraseblock as "un-mapped" in RAM. If UBI is detached before the physical
588  * eraseblock is physically erased, it will be mapped again to the same logical
589  * eraseblock when the MTD device is attached again.
590  *
591  * The main and obvious use-case of this function is when the contents of a
592  * logical eraseblock has to be re-written. Then it is much more efficient to
593  * first un-map it, then write new data, rather than first erase it, then write
594  * new data. Note, once new data has been written to the logical eraseblock,
595  * UBI guarantees that the old contents has gone forever. In other words, if an
596  * unclean reboot happens after the logical eraseblock has been un-mapped and
597  * then written to, it will contain the last written data.
598  *
599  * This function returns zero in case of success and a negative error code in
600  * case of failure. If the volume is damaged because of an interrupted update
601  * this function just returns immediately with %-EBADF code.
602  */
603 int ubi_leb_unmap(struct ubi_volume_desc *desc, int lnum)
604 {
605 	struct ubi_volume *vol = desc->vol;
606 	struct ubi_device *ubi = vol->ubi;
607 
608 	dbg_gen("unmap LEB %d:%d", vol->vol_id, lnum);
609 
610 	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
611 		return -EROFS;
612 
613 	if (lnum < 0 || lnum >= vol->reserved_pebs)
614 		return -EINVAL;
615 
616 	if (vol->upd_marker)
617 		return -EBADF;
618 
619 	return ubi_eba_unmap_leb(ubi, vol, lnum);
620 }
621 EXPORT_SYMBOL_GPL(ubi_leb_unmap);
622 
623 /**
624  * ubi_leb_map - map logical eraseblock to a physical eraseblock.
625  * @desc: volume descriptor
626  * @lnum: logical eraseblock number
627  * @dtype: expected data type
628  *
629  * This function maps an un-mapped logical eraseblock @lnum to a physical
630  * eraseblock. This means, that after a successful invocation of this
631  * function the logical eraseblock @lnum will be empty (contain only %0xFF
632  * bytes) and be mapped to a physical eraseblock, even if an unclean reboot
633  * happens.
634  *
635  * This function returns zero in case of success, %-EBADF if the volume is
636  * damaged because of an interrupted update, %-EBADMSG if the logical
637  * eraseblock is already mapped, and other negative error codes in case of
638  * other failures.
639  */
640 int ubi_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype)
641 {
642 	struct ubi_volume *vol = desc->vol;
643 	struct ubi_device *ubi = vol->ubi;
644 
645 	dbg_gen("unmap LEB %d:%d", vol->vol_id, lnum);
646 
647 	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
648 		return -EROFS;
649 
650 	if (lnum < 0 || lnum >= vol->reserved_pebs)
651 		return -EINVAL;
652 
653 	if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
654 	    dtype != UBI_UNKNOWN)
655 		return -EINVAL;
656 
657 	if (vol->upd_marker)
658 		return -EBADF;
659 
660 	if (vol->eba_tbl[lnum] >= 0)
661 		return -EBADMSG;
662 
663 	return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0, dtype);
664 }
665 EXPORT_SYMBOL_GPL(ubi_leb_map);
666 
667 /**
668  * ubi_is_mapped - check if logical eraseblock is mapped.
669  * @desc: volume descriptor
670  * @lnum: logical eraseblock number
671  *
672  * This function checks if logical eraseblock @lnum is mapped to a physical
673  * eraseblock. If a logical eraseblock is un-mapped, this does not necessarily
674  * mean it will still be un-mapped after the UBI device is re-attached. The
675  * logical eraseblock may become mapped to the physical eraseblock it was last
676  * mapped to.
677  *
678  * This function returns %1 if the LEB is mapped, %0 if not, and a negative
679  * error code in case of failure. If the volume is damaged because of an
680  * interrupted update this function just returns immediately with %-EBADF error
681  * code.
682  */
683 int ubi_is_mapped(struct ubi_volume_desc *desc, int lnum)
684 {
685 	struct ubi_volume *vol = desc->vol;
686 
687 	dbg_gen("test LEB %d:%d", vol->vol_id, lnum);
688 
689 	if (lnum < 0 || lnum >= vol->reserved_pebs)
690 		return -EINVAL;
691 
692 	if (vol->upd_marker)
693 		return -EBADF;
694 
695 	return vol->eba_tbl[lnum] >= 0;
696 }
697 EXPORT_SYMBOL_GPL(ubi_is_mapped);
698 
699 /**
700  * ubi_sync - synchronize UBI device buffers.
701  * @ubi_num: UBI device to synchronize
702  *
703  * The underlying MTD device may cache data in hardware or in software. This
704  * function ensures the caches are flushed. Returns zero in case of success and
705  * a negative error code in case of failure.
706  */
707 int ubi_sync(int ubi_num)
708 {
709 	struct ubi_device *ubi;
710 
711 	ubi = ubi_get_device(ubi_num);
712 	if (!ubi)
713 		return -ENODEV;
714 
715 	if (ubi->mtd->sync)
716 		ubi->mtd->sync(ubi->mtd);
717 
718 	ubi_put_device(ubi);
719 	return 0;
720 }
721 EXPORT_SYMBOL_GPL(ubi_sync);
722 
723 BLOCKING_NOTIFIER_HEAD(ubi_notifiers);
724 
725 /**
726  * ubi_register_volume_notifier - register a volume notifier.
727  * @nb: the notifier description object
728  * @ignore_existing: if non-zero, do not send "added" notification for all
729  *                   already existing volumes
730  *
731  * This function registers a volume notifier, which means that
732  * 'nb->notifier_call()' will be invoked when an UBI  volume is created,
733  * removed, re-sized, re-named, or updated. The first argument of the function
734  * is the notification type. The second argument is pointer to a
735  * &struct ubi_notification object which describes the notification event.
736  * Using UBI API from the volume notifier is prohibited.
737  *
738  * This function returns zero in case of success and a negative error code
739  * in case of failure.
740  */
741 int ubi_register_volume_notifier(struct notifier_block *nb,
742 				 int ignore_existing)
743 {
744 	int err;
745 
746 	err = blocking_notifier_chain_register(&ubi_notifiers, nb);
747 	if (err != 0)
748 		return err;
749 	if (ignore_existing)
750 		return 0;
751 
752 	/*
753 	 * We are going to walk all UBI devices and all volumes, and
754 	 * notify the user about existing volumes by the %UBI_VOLUME_ADDED
755 	 * event. We have to lock the @ubi_devices_mutex to make sure UBI
756 	 * devices do not disappear.
757 	 */
758 	mutex_lock(&ubi_devices_mutex);
759 	ubi_enumerate_volumes(nb);
760 	mutex_unlock(&ubi_devices_mutex);
761 
762 	return err;
763 }
764 EXPORT_SYMBOL_GPL(ubi_register_volume_notifier);
765 
766 /**
767  * ubi_unregister_volume_notifier - unregister the volume notifier.
768  * @nb: the notifier description object
769  *
770  * This function unregisters volume notifier @nm and returns zero in case of
771  * success and a negative error code in case of failure.
772  */
773 int ubi_unregister_volume_notifier(struct notifier_block *nb)
774 {
775 	return blocking_notifier_chain_unregister(&ubi_notifiers, nb);
776 }
777 EXPORT_SYMBOL_GPL(ubi_unregister_volume_notifier);
778