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: Adrian Hunter
20 *          Artem Bityutskiy (���������������� ����������)
21 */
22
23/*
24 * This file implements the scan which is a general-purpose function for
25 * determining what nodes are in an eraseblock. The scan is used to replay the
26 * journal, to do garbage collection. for the TNC in-the-gaps method, and by
27 * debugging functions.
28 */
29
30#include "ubifs.h"
31
32/**
33 * scan_padding_bytes - scan for padding bytes.
34 * @buf: buffer to scan
35 * @len: length of buffer
36 *
37 * This function returns the number of padding bytes on success and
38 * %SCANNED_GARBAGE on failure.
39 */
40static int scan_padding_bytes(void *buf, int len)
41{
42	int pad_len = 0, max_pad_len = min_t(int, UBIFS_PAD_NODE_SZ, len);
43	uint8_t *p = buf;
44
45	dbg_scan("not a node");
46
47	while (pad_len < max_pad_len && *p++ == UBIFS_PADDING_BYTE)
48		pad_len += 1;
49
50	if (!pad_len || (pad_len & 7))
51		return SCANNED_GARBAGE;
52
53	dbg_scan("%d padding bytes", pad_len);
54
55	return pad_len;
56}
57
58/**
59 * ubifs_scan_a_node - scan for a node or padding.
60 * @c: UBIFS file-system description object
61 * @buf: buffer to scan
62 * @len: length of buffer
63 * @lnum: logical eraseblock number
64 * @offs: offset within the logical eraseblock
65 * @quiet: print no messages
66 *
67 * This function returns a scanning code to indicate what was scanned.
68 */
69int ubifs_scan_a_node(const struct ubifs_info *c, void *buf, int len, int lnum,
70		      int offs, int quiet)
71{
72	struct ubifs_ch *ch = buf;
73	uint32_t magic;
74
75	magic = le32_to_cpu(ch->magic);
76
77	if (magic == 0xFFFFFFFF) {
78		dbg_scan("hit empty space");
79		return SCANNED_EMPTY_SPACE;
80	}
81
82	if (magic != UBIFS_NODE_MAGIC)
83		return scan_padding_bytes(buf, len);
84
85	if (len < UBIFS_CH_SZ)
86		return SCANNED_GARBAGE;
87
88	dbg_scan("scanning %s", dbg_ntype(ch->node_type));
89
90	if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
91		return SCANNED_A_CORRUPT_NODE;
92
93	if (ch->node_type == UBIFS_PAD_NODE) {
94		struct ubifs_pad_node *pad = buf;
95		int pad_len = le32_to_cpu(pad->pad_len);
96		int node_len = le32_to_cpu(ch->len);
97
98		/* Validate the padding node */
99		if (pad_len < 0 ||
100		    offs + node_len + pad_len > c->leb_size) {
101			if (!quiet) {
102				ubifs_err("bad pad node at LEB %d:%d",
103					  lnum, offs);
104				dbg_dump_node(c, pad);
105			}
106			return SCANNED_A_BAD_PAD_NODE;
107		}
108
109		/* Make the node pads to 8-byte boundary */
110		if ((node_len + pad_len) & 7) {
111			if (!quiet)
112				dbg_err("bad padding length %d - %d",
113					offs, offs + node_len + pad_len);
114			return SCANNED_A_BAD_PAD_NODE;
115		}
116
117		dbg_scan("%d bytes padded, offset now %d",
118			 pad_len, ALIGN(offs + node_len + pad_len, 8));
119
120		return node_len + pad_len;
121	}
122
123	return SCANNED_A_NODE;
124}
125
126/**
127 * ubifs_start_scan - create LEB scanning information at start of scan.
128 * @c: UBIFS file-system description object
129 * @lnum: logical eraseblock number
130 * @offs: offset to start at (usually zero)
131 * @sbuf: scan buffer (must be c->leb_size)
132 *
133 * This function returns %0 on success and a negative error code on failure.
134 */
135struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
136					int offs, void *sbuf)
137{
138	struct ubifs_scan_leb *sleb;
139	int err;
140
141	dbg_scan("scan LEB %d:%d", lnum, offs);
142
143	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
144	if (!sleb)
145		return ERR_PTR(-ENOMEM);
146
147	sleb->lnum = lnum;
148	INIT_LIST_HEAD(&sleb->nodes);
149	sleb->buf = sbuf;
150
151	err = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
152	if (err && err != -EBADMSG) {
153		ubifs_err("cannot read %d bytes from LEB %d:%d,"
154			  " error %d", c->leb_size - offs, lnum, offs, err);
155		kfree(sleb);
156		return ERR_PTR(err);
157	}
158
159	if (err == -EBADMSG)
160		sleb->ecc = 1;
161
162	return sleb;
163}
164
165/**
166 * ubifs_end_scan - update LEB scanning information at end of scan.
167 * @c: UBIFS file-system description object
168 * @sleb: scanning information
169 * @lnum: logical eraseblock number
170 * @offs: offset to start at (usually zero)
171 *
172 * This function returns %0 on success and a negative error code on failure.
173 */
174void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
175		    int lnum, int offs)
176{
177	lnum = lnum;
178	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
179	ubifs_assert(offs % c->min_io_size == 0);
180
181	sleb->endpt = ALIGN(offs, c->min_io_size);
182}
183
184/**
185 * ubifs_add_snod - add a scanned node to LEB scanning information.
186 * @c: UBIFS file-system description object
187 * @sleb: scanning information
188 * @buf: buffer containing node
189 * @offs: offset of node on flash
190 *
191 * This function returns %0 on success and a negative error code on failure.
192 */
193int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
194		   void *buf, int offs)
195{
196	struct ubifs_ch *ch = buf;
197	struct ubifs_ino_node *ino = buf;
198	struct ubifs_scan_node *snod;
199
200	snod = kzalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
201	if (!snod)
202		return -ENOMEM;
203
204	snod->sqnum = le64_to_cpu(ch->sqnum);
205	snod->type = ch->node_type;
206	snod->offs = offs;
207	snod->len = le32_to_cpu(ch->len);
208	snod->node = buf;
209
210	switch (ch->node_type) {
211	case UBIFS_INO_NODE:
212	case UBIFS_DENT_NODE:
213	case UBIFS_XENT_NODE:
214	case UBIFS_DATA_NODE:
215	case UBIFS_TRUN_NODE:
216		/*
217		 * The key is in the same place in all keyed
218		 * nodes.
219		 */
220		key_read(c, &ino->key, &snod->key);
221		break;
222	}
223	list_add_tail(&snod->list, &sleb->nodes);
224	sleb->nodes_cnt += 1;
225	return 0;
226}
227
228/**
229 * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
230 * @c: UBIFS file-system description object
231 * @lnum: LEB number of corruption
232 * @offs: offset of corruption
233 * @buf: buffer containing corruption
234 */
235void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
236			      void *buf)
237{
238	int len;
239
240	ubifs_err("corruption at LEB %d:%d", lnum, offs);
241	if (dbg_failure_mode)
242		return;
243	len = c->leb_size - offs;
244	if (len > 8192)
245		len = 8192;
246	dbg_err("first %d bytes from LEB %d:%d", len, lnum, offs);
247	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
248}
249
250/**
251 * ubifs_scan - scan a logical eraseblock.
252 * @c: UBIFS file-system description object
253 * @lnum: logical eraseblock number
254 * @offs: offset to start at (usually zero)
255 * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
256 * @quiet: print no messages
257 *
258 * This function scans LEB number @lnum and returns complete information about
259 * its contents. Returns the scaned information in case of success and,
260 * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
261 * of failure.
262 *
263 * If @quiet is non-zero, this function does not print large and scary
264 * error messages and flash dumps in case of errors.
265 */
266struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
267				  int offs, void *sbuf, int quiet)
268{
269	void *buf = sbuf + offs;
270	int err, len = c->leb_size - offs;
271	struct ubifs_scan_leb *sleb;
272
273	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
274	if (IS_ERR(sleb))
275		return sleb;
276
277	while (len >= 8) {
278		struct ubifs_ch *ch = buf;
279		int node_len, ret;
280
281		dbg_scan("look at LEB %d:%d (%d bytes left)",
282			 lnum, offs, len);
283
284		cond_resched();
285
286		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
287		if (ret > 0) {
288			/* Padding bytes or a valid padding node */
289			offs += ret;
290			buf += ret;
291			len -= ret;
292			continue;
293		}
294
295		if (ret == SCANNED_EMPTY_SPACE)
296			/* Empty space is checked later */
297			break;
298
299		switch (ret) {
300		case SCANNED_GARBAGE:
301			dbg_err("garbage");
302			goto corrupted;
303		case SCANNED_A_NODE:
304			break;
305		case SCANNED_A_CORRUPT_NODE:
306		case SCANNED_A_BAD_PAD_NODE:
307			dbg_err("bad node");
308			goto corrupted;
309		default:
310			dbg_err("unknown");
311			err = -EINVAL;
312			goto error;
313		}
314
315		err = ubifs_add_snod(c, sleb, buf, offs);
316		if (err)
317			goto error;
318
319		node_len = ALIGN(le32_to_cpu(ch->len), 8);
320		offs += node_len;
321		buf += node_len;
322		len -= node_len;
323	}
324
325	if (offs % c->min_io_size) {
326		if (!quiet)
327			ubifs_err("empty space starts at non-aligned offset %d",
328				  offs);
329		goto corrupted;;
330	}
331
332	ubifs_end_scan(c, sleb, lnum, offs);
333
334	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
335		if (*(uint32_t *)buf != 0xffffffff)
336			break;
337	for (; len; offs++, buf++, len--)
338		if (*(uint8_t *)buf != 0xff) {
339			if (!quiet)
340				ubifs_err("corrupt empty space at LEB %d:%d",
341					  lnum, offs);
342			goto corrupted;
343		}
344
345	return sleb;
346
347corrupted:
348	if (!quiet) {
349		ubifs_scanned_corruption(c, lnum, offs, buf);
350		ubifs_err("LEB %d scanning failed", lnum);
351	}
352	err = -EUCLEAN;
353	ubifs_scan_destroy(sleb);
354	return ERR_PTR(err);
355
356error:
357	ubifs_err("LEB %d scanning failed, error %d", lnum, err);
358	ubifs_scan_destroy(sleb);
359	return ERR_PTR(err);
360}
361
362/**
363 * ubifs_scan_destroy - destroy LEB scanning information.
364 * @sleb: scanning information to free
365 */
366void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
367{
368	struct ubifs_scan_node *node;
369	struct list_head *head;
370
371	head = &sleb->nodes;
372	while (!list_empty(head)) {
373		node = list_entry(head->next, struct ubifs_scan_node, list);
374		list_del(&node->list);
375		kfree(node);
376	}
377	kfree(sleb);
378}
379