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1 // SPDX-License-Identifier: GPL-2.0+
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 #ifndef __UBOOT__
29 #include <linux/uaccess.h>
30 #else
31 #include <div64.h>
32 #include <ubi_uboot.h>
33 #endif
34 #include <linux/err.h>
35 #include <linux/math64.h>
36 
37 #include "ubi.h"
38 
39 /**
40  * set_update_marker - set update marker.
41  * @ubi: UBI device description object
42  * @vol: volume description object
43  *
44  * This function sets the update marker flag for volume @vol. Returns zero
45  * in case of success and a negative error code in case of failure.
46  */
set_update_marker(struct ubi_device * ubi,struct ubi_volume * vol)47 static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
48 {
49 	int err;
50 	struct ubi_vtbl_record vtbl_rec;
51 
52 	dbg_gen("set update marker for volume %d", vol->vol_id);
53 
54 	if (vol->upd_marker) {
55 		ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
56 		dbg_gen("already set");
57 		return 0;
58 	}
59 
60 	vtbl_rec = ubi->vtbl[vol->vol_id];
61 	vtbl_rec.upd_marker = 1;
62 
63 	mutex_lock(&ubi->device_mutex);
64 	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
65 	vol->upd_marker = 1;
66 	mutex_unlock(&ubi->device_mutex);
67 	return err;
68 }
69 
70 /**
71  * clear_update_marker - clear update marker.
72  * @ubi: UBI device description object
73  * @vol: volume description object
74  * @bytes: new data size in bytes
75  *
76  * This function clears the update marker for volume @vol, sets new volume
77  * data size and clears the "corrupted" flag (static volumes only). Returns
78  * zero in case of success and a negative error code in case of failure.
79  */
clear_update_marker(struct ubi_device * ubi,struct ubi_volume * vol,long long bytes)80 static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
81 			       long long bytes)
82 {
83 	int err;
84 	struct ubi_vtbl_record vtbl_rec;
85 
86 	dbg_gen("clear update marker for volume %d", vol->vol_id);
87 
88 	vtbl_rec = ubi->vtbl[vol->vol_id];
89 	ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
90 	vtbl_rec.upd_marker = 0;
91 
92 	if (vol->vol_type == UBI_STATIC_VOLUME) {
93 		vol->corrupted = 0;
94 		vol->used_bytes = bytes;
95 		vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
96 					    &vol->last_eb_bytes);
97 		if (vol->last_eb_bytes)
98 			vol->used_ebs += 1;
99 		else
100 			vol->last_eb_bytes = vol->usable_leb_size;
101 	}
102 
103 	mutex_lock(&ubi->device_mutex);
104 	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
105 	vol->upd_marker = 0;
106 	mutex_unlock(&ubi->device_mutex);
107 	return err;
108 }
109 
110 /**
111  * ubi_start_update - start volume update.
112  * @ubi: UBI device description object
113  * @vol: volume description object
114  * @bytes: update bytes
115  *
116  * This function starts volume update operation. If @bytes is zero, the volume
117  * is just wiped out. Returns zero in case of success and a negative error code
118  * in case of failure.
119  */
ubi_start_update(struct ubi_device * ubi,struct ubi_volume * vol,long long bytes)120 int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
121 		     long long bytes)
122 {
123 	int i, err;
124 
125 	dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
126 	ubi_assert(!vol->updating && !vol->changing_leb);
127 	vol->updating = 1;
128 
129 	vol->upd_buf = vmalloc(ubi->leb_size);
130 	if (!vol->upd_buf)
131 		return -ENOMEM;
132 
133 	err = set_update_marker(ubi, vol);
134 	if (err)
135 		return err;
136 
137 	/* Before updating - wipe out the volume */
138 	for (i = 0; i < vol->reserved_pebs; i++) {
139 		err = ubi_eba_unmap_leb(ubi, vol, i);
140 		if (err)
141 			return err;
142 	}
143 
144 	if (bytes == 0) {
145 		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
146 		if (err)
147 			return err;
148 
149 		err = clear_update_marker(ubi, vol, 0);
150 		if (err)
151 			return err;
152 
153 		vfree(vol->upd_buf);
154 		vol->updating = 0;
155 		return 0;
156 	}
157 
158 	vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
159 			       vol->usable_leb_size);
160 	vol->upd_bytes = bytes;
161 	vol->upd_received = 0;
162 	return 0;
163 }
164 
165 /**
166  * ubi_start_leb_change - start atomic LEB change.
167  * @ubi: UBI device description object
168  * @vol: volume description object
169  * @req: operation request
170  *
171  * This function starts atomic LEB change operation. Returns zero in case of
172  * success and a negative error code in case of failure.
173  */
ubi_start_leb_change(struct ubi_device * ubi,struct ubi_volume * vol,const struct ubi_leb_change_req * req)174 int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
175 			 const struct ubi_leb_change_req *req)
176 {
177 	ubi_assert(!vol->updating && !vol->changing_leb);
178 
179 	dbg_gen("start changing LEB %d:%d, %u bytes",
180 		vol->vol_id, req->lnum, req->bytes);
181 	if (req->bytes == 0)
182 		return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
183 
184 	vol->upd_bytes = req->bytes;
185 	vol->upd_received = 0;
186 	vol->changing_leb = 1;
187 	vol->ch_lnum = req->lnum;
188 
189 	vol->upd_buf = vmalloc(req->bytes);
190 	if (!vol->upd_buf)
191 		return -ENOMEM;
192 
193 	return 0;
194 }
195 
196 /**
197  * write_leb - write update data.
198  * @ubi: UBI device description object
199  * @vol: volume description object
200  * @lnum: logical eraseblock number
201  * @buf: data to write
202  * @len: data size
203  * @used_ebs: how many logical eraseblocks will this volume contain (static
204  * volumes only)
205  *
206  * This function writes update data to corresponding logical eraseblock. In
207  * case of dynamic volume, this function checks if the data contains 0xFF bytes
208  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
209  * buffer contains only 0xFF bytes, the LEB is left unmapped.
210  *
211  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
212  * that we want to make sure that more data may be appended to the logical
213  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
214  * this PEB won't be writable anymore. So if one writes the file-system image
215  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
216  * space is writable after the update.
217  *
218  * We do not do this for static volumes because they are read-only. But this
219  * also cannot be done because we have to store per-LEB CRC and the correct
220  * data length.
221  *
222  * This function returns zero in case of success and a negative error code in
223  * case of failure.
224  */
write_leb(struct ubi_device * ubi,struct ubi_volume * vol,int lnum,void * buf,int len,int used_ebs)225 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
226 		     void *buf, int len, int used_ebs)
227 {
228 	int err;
229 
230 	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
231 		int l = ALIGN(len, ubi->min_io_size);
232 
233 		memset(buf + len, 0xFF, l - len);
234 		len = ubi_calc_data_len(ubi, buf, l);
235 		if (len == 0) {
236 			dbg_gen("all %d bytes contain 0xFF - skip", len);
237 			return 0;
238 		}
239 
240 		err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
241 	} else {
242 		/*
243 		 * When writing static volume, and this is the last logical
244 		 * eraseblock, the length (@len) does not have to be aligned to
245 		 * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
246 		 * function accepts exact (unaligned) length and stores it in
247 		 * the VID header. And it takes care of proper alignment by
248 		 * padding the buffer. Here we just make sure the padding will
249 		 * contain zeros, not random trash.
250 		 */
251 		memset(buf + len, 0, vol->usable_leb_size - len);
252 		err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
253 	}
254 
255 	return err;
256 }
257 
258 /**
259  * ubi_more_update_data - write more update data.
260  * @ubi: UBI device description object
261  * @vol: volume description object
262  * @buf: write data (user-space memory buffer)
263  * @count: how much bytes to write
264  *
265  * This function writes more data to the volume which is being updated. It may
266  * be called arbitrary number of times until all the update data arriveis. This
267  * function returns %0 in case of success, number of bytes written during the
268  * last call if the whole volume update has been successfully finished, and a
269  * negative error code in case of failure.
270  */
ubi_more_update_data(struct ubi_device * ubi,struct ubi_volume * vol,const void __user * buf,int count)271 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
272 			 const void __user *buf, int count)
273 {
274 #ifndef __UBOOT__
275 	int lnum, offs, err = 0, len, to_write = count;
276 #else
277 	int lnum, err = 0, len, to_write = count;
278 	u32 offs;
279 #endif
280 
281 	dbg_gen("write %d of %lld bytes, %lld already passed",
282 		count, vol->upd_bytes, vol->upd_received);
283 
284 	if (ubi->ro_mode)
285 		return -EROFS;
286 
287 	lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
288 	if (vol->upd_received + count > vol->upd_bytes)
289 		to_write = count = vol->upd_bytes - vol->upd_received;
290 
291 	/*
292 	 * When updating volumes, we accumulate whole logical eraseblock of
293 	 * data and write it at once.
294 	 */
295 	if (offs != 0) {
296 		/*
297 		 * This is a write to the middle of the logical eraseblock. We
298 		 * copy the data to our update buffer and wait for more data or
299 		 * flush it if the whole eraseblock is written or the update
300 		 * is finished.
301 		 */
302 
303 		len = vol->usable_leb_size - offs;
304 		if (len > count)
305 			len = count;
306 
307 		err = copy_from_user(vol->upd_buf + offs, buf, len);
308 		if (err)
309 			return -EFAULT;
310 
311 		if (offs + len == vol->usable_leb_size ||
312 		    vol->upd_received + len == vol->upd_bytes) {
313 			int flush_len = offs + len;
314 
315 			/*
316 			 * OK, we gathered either the whole eraseblock or this
317 			 * is the last chunk, it's time to flush the buffer.
318 			 */
319 			ubi_assert(flush_len <= vol->usable_leb_size);
320 			err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
321 					vol->upd_ebs);
322 			if (err)
323 				return err;
324 		}
325 
326 		vol->upd_received += len;
327 		count -= len;
328 		buf += len;
329 		lnum += 1;
330 	}
331 
332 	/*
333 	 * If we've got more to write, let's continue. At this point we know we
334 	 * are starting from the beginning of an eraseblock.
335 	 */
336 	while (count) {
337 		if (count > vol->usable_leb_size)
338 			len = vol->usable_leb_size;
339 		else
340 			len = count;
341 
342 		err = copy_from_user(vol->upd_buf, buf, len);
343 		if (err)
344 			return -EFAULT;
345 
346 		if (len == vol->usable_leb_size ||
347 		    vol->upd_received + len == vol->upd_bytes) {
348 			err = write_leb(ubi, vol, lnum, vol->upd_buf,
349 					len, vol->upd_ebs);
350 			if (err)
351 				break;
352 		}
353 
354 		vol->upd_received += len;
355 		count -= len;
356 		lnum += 1;
357 		buf += len;
358 	}
359 
360 	ubi_assert(vol->upd_received <= vol->upd_bytes);
361 	if (vol->upd_received == vol->upd_bytes) {
362 		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
363 		if (err)
364 			return err;
365 		/* The update is finished, clear the update marker */
366 		err = clear_update_marker(ubi, vol, vol->upd_bytes);
367 		if (err)
368 			return err;
369 		vol->updating = 0;
370 		err = to_write;
371 		vfree(vol->upd_buf);
372 	}
373 
374 	return err;
375 }
376 
377 /**
378  * ubi_more_leb_change_data - accept more data for atomic LEB change.
379  * @ubi: UBI device description object
380  * @vol: volume description object
381  * @buf: write data (user-space memory buffer)
382  * @count: how much bytes to write
383  *
384  * This function accepts more data to the volume which is being under the
385  * "atomic LEB change" operation. It may be called arbitrary number of times
386  * until all data arrives. This function returns %0 in case of success, number
387  * of bytes written during the last call if the whole "atomic LEB change"
388  * operation has been successfully finished, and a negative error code in case
389  * of failure.
390  */
ubi_more_leb_change_data(struct ubi_device * ubi,struct ubi_volume * vol,const void __user * buf,int count)391 int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
392 			     const void __user *buf, int count)
393 {
394 	int err;
395 
396 	dbg_gen("write %d of %lld bytes, %lld already passed",
397 		count, vol->upd_bytes, vol->upd_received);
398 
399 	if (ubi->ro_mode)
400 		return -EROFS;
401 
402 	if (vol->upd_received + count > vol->upd_bytes)
403 		count = vol->upd_bytes - vol->upd_received;
404 
405 	err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
406 	if (err)
407 		return -EFAULT;
408 
409 	vol->upd_received += count;
410 
411 	if (vol->upd_received == vol->upd_bytes) {
412 		int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
413 
414 		memset(vol->upd_buf + vol->upd_bytes, 0xFF,
415 		       len - vol->upd_bytes);
416 		len = ubi_calc_data_len(ubi, vol->upd_buf, len);
417 		err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
418 						vol->upd_buf, len);
419 		if (err)
420 			return err;
421 	}
422 
423 	ubi_assert(vol->upd_received <= vol->upd_bytes);
424 	if (vol->upd_received == vol->upd_bytes) {
425 		vol->changing_leb = 0;
426 		err = count;
427 		vfree(vol->upd_buf);
428 	}
429 
430 	return err;
431 }
432