1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) International Business Machines Corp., 2006
4 * Copyright (c) Nokia Corporation, 2006
5 *
6 * Author: Artem Bityutskiy (Битюцкий Артём)
7 *
8 * Jan 2007: Alexander Schmidt, hacked per-volume update.
9 */
10
11 /*
12 * This file contains implementation of the volume update and atomic LEB change
13 * functionality.
14 *
15 * The update operation is based on the per-volume update marker which is
16 * stored in the volume table. The update marker is set before the update
17 * starts, and removed after the update has been finished. So if the update was
18 * interrupted by an unclean re-boot or due to some other reasons, the update
19 * marker stays on the flash media and UBI finds it when it attaches the MTD
20 * device next time. If the update marker is set for a volume, the volume is
21 * treated as damaged and most I/O operations are prohibited. Only a new update
22 * operation is allowed.
23 *
24 * Note, in general it is possible to implement the update operation as a
25 * transaction with a roll-back capability.
26 */
27
28 #include <linux/err.h>
29 #include <linux/uaccess.h>
30 #include <linux/math64.h>
31 #include "ubi.h"
32
33 /**
34 * set_update_marker - set update marker.
35 * @ubi: UBI device description object
36 * @vol: volume description object
37 *
38 * This function sets the update marker flag for volume @vol. Returns zero
39 * in case of success and a negative error code in case of failure.
40 */
41 static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
42 {
43 int err;
44 struct ubi_vtbl_record vtbl_rec;
45
46 dbg_gen("set update marker for volume %d", vol->vol_id);
47
48 if (vol->upd_marker) {
49 ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
50 dbg_gen("already set");
51 return 0;
52 }
53
54 vtbl_rec = ubi->vtbl[vol->vol_id];
55 vtbl_rec.upd_marker = 1;
56
57 mutex_lock(&ubi->device_mutex);
58 err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
59 vol->upd_marker = 1;
60 mutex_unlock(&ubi->device_mutex);
61 return err;
62 }
63
64 /**
65 * clear_update_marker - clear update marker.
66 * @ubi: UBI device description object
67 * @vol: volume description object
68 * @bytes: new data size in bytes
69 *
70 * This function clears the update marker for volume @vol, sets new volume
71 * data size and clears the "corrupted" flag (static volumes only). Returns
72 * zero in case of success and a negative error code in case of failure.
73 */
74 static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
75 long long bytes)
76 {
77 int err;
78 struct ubi_vtbl_record vtbl_rec;
79
80 dbg_gen("clear update marker for volume %d", vol->vol_id);
81
82 vtbl_rec = ubi->vtbl[vol->vol_id];
83 ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
84 vtbl_rec.upd_marker = 0;
85
86 if (vol->vol_type == UBI_STATIC_VOLUME) {
87 vol->corrupted = 0;
88 vol->used_bytes = bytes;
89 vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
90 &vol->last_eb_bytes);
91 if (vol->last_eb_bytes)
92 vol->used_ebs += 1;
93 else
94 vol->last_eb_bytes = vol->usable_leb_size;
95 }
96
97 mutex_lock(&ubi->device_mutex);
98 err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
99 vol->upd_marker = 0;
100 mutex_unlock(&ubi->device_mutex);
101 return err;
102 }
103
104 /**
105 * ubi_start_update - start volume update.
106 * @ubi: UBI device description object
107 * @vol: volume description object
108 * @bytes: update bytes
109 *
110 * This function starts volume update operation. If @bytes is zero, the volume
111 * is just wiped out. Returns zero in case of success and a negative error code
112 * in case of failure.
113 */
114 int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
115 long long bytes)
116 {
117 int i, err;
118
119 dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
120 ubi_assert(!vol->updating && !vol->changing_leb);
121 vol->updating = 1;
122
123 vol->upd_buf = vmalloc(ubi->leb_size);
124 if (!vol->upd_buf)
125 return -ENOMEM;
126
127 err = set_update_marker(ubi, vol);
128 if (err)
129 return err;
130
131 /* Before updating - wipe out the volume */
132 for (i = 0; i < vol->reserved_pebs; i++) {
133 err = ubi_eba_unmap_leb(ubi, vol, i);
134 if (err)
135 return err;
136 }
137
138 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
139 if (err)
140 return err;
141
142 if (bytes == 0) {
143 err = clear_update_marker(ubi, vol, 0);
144 if (err)
145 return err;
146
147 vfree(vol->upd_buf);
148 vol->updating = 0;
149 return 0;
150 }
151
152 vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
153 vol->usable_leb_size);
154 vol->upd_bytes = bytes;
155 vol->upd_received = 0;
156 return 0;
157 }
158
159 /**
160 * ubi_start_leb_change - start atomic LEB change.
161 * @ubi: UBI device description object
162 * @vol: volume description object
163 * @req: operation request
164 *
165 * This function starts atomic LEB change operation. Returns zero in case of
166 * success and a negative error code in case of failure.
167 */
168 int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
169 const struct ubi_leb_change_req *req)
170 {
171 ubi_assert(!vol->updating && !vol->changing_leb);
172
173 dbg_gen("start changing LEB %d:%d, %u bytes",
174 vol->vol_id, req->lnum, req->bytes);
175 if (req->bytes == 0)
176 return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
177
178 vol->upd_bytes = req->bytes;
179 vol->upd_received = 0;
180 vol->changing_leb = 1;
181 vol->ch_lnum = req->lnum;
182
183 vol->upd_buf = vmalloc(ALIGN((int)req->bytes, ubi->min_io_size));
184 if (!vol->upd_buf)
185 return -ENOMEM;
186
187 return 0;
188 }
189
190 /**
191 * write_leb - write update data.
192 * @ubi: UBI device description object
193 * @vol: volume description object
194 * @lnum: logical eraseblock number
195 * @buf: data to write
196 * @len: data size
197 * @used_ebs: how many logical eraseblocks will this volume contain (static
198 * volumes only)
199 *
200 * This function writes update data to corresponding logical eraseblock. In
201 * case of dynamic volume, this function checks if the data contains 0xFF bytes
202 * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
203 * buffer contains only 0xFF bytes, the LEB is left unmapped.
204 *
205 * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
206 * that we want to make sure that more data may be appended to the logical
207 * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
208 * this PEB won't be writable anymore. So if one writes the file-system image
209 * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
210 * space is writable after the update.
211 *
212 * We do not do this for static volumes because they are read-only. But this
213 * also cannot be done because we have to store per-LEB CRC and the correct
214 * data length.
215 *
216 * This function returns zero in case of success and a negative error code in
217 * case of failure.
218 */
219 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
220 void *buf, int len, int used_ebs)
221 {
222 int err;
223
224 if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
225 int l = ALIGN(len, ubi->min_io_size);
226
227 memset(buf + len, 0xFF, l - len);
228 len = ubi_calc_data_len(ubi, buf, l);
229 if (len == 0) {
230 dbg_gen("all %d bytes contain 0xFF - skip", len);
231 return 0;
232 }
233
234 err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
235 } else {
236 /*
237 * When writing static volume, and this is the last logical
238 * eraseblock, the length (@len) does not have to be aligned to
239 * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
240 * function accepts exact (unaligned) length and stores it in
241 * the VID header. And it takes care of proper alignment by
242 * padding the buffer. Here we just make sure the padding will
243 * contain zeros, not random trash.
244 */
245 memset(buf + len, 0, vol->usable_leb_size - len);
246 err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
247 }
248
249 return err;
250 }
251
252 /**
253 * ubi_more_update_data - write more update data.
254 * @ubi: UBI device description object
255 * @vol: volume description object
256 * @buf: write data (user-space memory buffer)
257 * @count: how much bytes to write
258 *
259 * This function writes more data to the volume which is being updated. It may
260 * be called arbitrary number of times until all the update data arriveis. This
261 * function returns %0 in case of success, number of bytes written during the
262 * last call if the whole volume update has been successfully finished, and a
263 * negative error code in case of failure.
264 */
265 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
266 const void __user *buf, int count)
267 {
268 int lnum, offs, err = 0, len, to_write = count;
269
270 dbg_gen("write %d of %lld bytes, %lld already passed",
271 count, vol->upd_bytes, vol->upd_received);
272
273 if (ubi->ro_mode)
274 return -EROFS;
275
276 lnum = div_u64_rem(vol->upd_received, vol->usable_leb_size, &offs);
277 if (vol->upd_received + count > vol->upd_bytes)
278 to_write = count = vol->upd_bytes - vol->upd_received;
279
280 /*
281 * When updating volumes, we accumulate whole logical eraseblock of
282 * data and write it at once.
283 */
284 if (offs != 0) {
285 /*
286 * This is a write to the middle of the logical eraseblock. We
287 * copy the data to our update buffer and wait for more data or
288 * flush it if the whole eraseblock is written or the update
289 * is finished.
290 */
291
292 len = vol->usable_leb_size - offs;
293 if (len > count)
294 len = count;
295
296 err = copy_from_user(vol->upd_buf + offs, buf, len);
297 if (err)
298 return -EFAULT;
299
300 if (offs + len == vol->usable_leb_size ||
301 vol->upd_received + len == vol->upd_bytes) {
302 int flush_len = offs + len;
303
304 /*
305 * OK, we gathered either the whole eraseblock or this
306 * is the last chunk, it's time to flush the buffer.
307 */
308 ubi_assert(flush_len <= vol->usable_leb_size);
309 err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
310 vol->upd_ebs);
311 if (err)
312 return err;
313 }
314
315 vol->upd_received += len;
316 count -= len;
317 buf += len;
318 lnum += 1;
319 }
320
321 /*
322 * If we've got more to write, let's continue. At this point we know we
323 * are starting from the beginning of an eraseblock.
324 */
325 while (count) {
326 if (count > vol->usable_leb_size)
327 len = vol->usable_leb_size;
328 else
329 len = count;
330
331 err = copy_from_user(vol->upd_buf, buf, len);
332 if (err)
333 return -EFAULT;
334
335 if (len == vol->usable_leb_size ||
336 vol->upd_received + len == vol->upd_bytes) {
337 err = write_leb(ubi, vol, lnum, vol->upd_buf,
338 len, vol->upd_ebs);
339 if (err)
340 break;
341 }
342
343 vol->upd_received += len;
344 count -= len;
345 lnum += 1;
346 buf += len;
347 }
348
349 ubi_assert(vol->upd_received <= vol->upd_bytes);
350 if (vol->upd_received == vol->upd_bytes) {
351 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
352 if (err)
353 return err;
354 /* The update is finished, clear the update marker */
355 err = clear_update_marker(ubi, vol, vol->upd_bytes);
356 if (err)
357 return err;
358 vol->updating = 0;
359 err = to_write;
360 vfree(vol->upd_buf);
361 }
362
363 return err;
364 }
365
366 /**
367 * ubi_more_leb_change_data - accept more data for atomic LEB change.
368 * @ubi: UBI device description object
369 * @vol: volume description object
370 * @buf: write data (user-space memory buffer)
371 * @count: how much bytes to write
372 *
373 * This function accepts more data to the volume which is being under the
374 * "atomic LEB change" operation. It may be called arbitrary number of times
375 * until all data arrives. This function returns %0 in case of success, number
376 * of bytes written during the last call if the whole "atomic LEB change"
377 * operation has been successfully finished, and a negative error code in case
378 * of failure.
379 */
380 int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
381 const void __user *buf, int count)
382 {
383 int err;
384
385 dbg_gen("write %d of %lld bytes, %lld already passed",
386 count, vol->upd_bytes, vol->upd_received);
387
388 if (ubi->ro_mode)
389 return -EROFS;
390
391 if (vol->upd_received + count > vol->upd_bytes)
392 count = vol->upd_bytes - vol->upd_received;
393
394 err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
395 if (err)
396 return -EFAULT;
397
398 vol->upd_received += count;
399
400 if (vol->upd_received == vol->upd_bytes) {
401 int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
402
403 memset(vol->upd_buf + vol->upd_bytes, 0xFF,
404 len - vol->upd_bytes);
405 len = ubi_calc_data_len(ubi, vol->upd_buf, len);
406 err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
407 vol->upd_buf, len);
408 if (err)
409 return err;
410 }
411
412 ubi_assert(vol->upd_received <= vol->upd_bytes);
413 if (vol->upd_received == vol->upd_bytes) {
414 vol->changing_leb = 0;
415 err = count;
416 vfree(vol->upd_buf);
417 }
418
419 return err;
420 }