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 (Битюцкий Артём)
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 at LEB %d:%d", lnum, offs);
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 at LEB %d:%d",
89		 dbg_ntype(ch->node_type), lnum, offs);
90
91	if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
92		return SCANNED_A_CORRUPT_NODE;
93
94	if (ch->node_type == UBIFS_PAD_NODE) {
95		struct ubifs_pad_node *pad = buf;
96		int pad_len = le32_to_cpu(pad->pad_len);
97		int node_len = le32_to_cpu(ch->len);
98
99		/* Validate the padding node */
100		if (pad_len < 0 ||
101		    offs + node_len + pad_len > c->leb_size) {
102			if (!quiet) {
103				ubifs_err(c, "bad pad node at LEB %d:%d",
104					  lnum, offs);
105				ubifs_dump_node(c, pad);
106			}
107			return SCANNED_A_BAD_PAD_NODE;
108		}
109
110		/* Make the node pads to 8-byte boundary */
111		if ((node_len + pad_len) & 7) {
112			if (!quiet)
113				ubifs_err(c, "bad padding length %d - %d",
114					  offs, offs + node_len + pad_len);
115			return SCANNED_A_BAD_PAD_NODE;
116		}
117
118		dbg_scan("%d bytes padded at LEB %d:%d, offset now %d", pad_len,
119			 lnum, offs, ALIGN(offs + node_len + pad_len, 8));
120
121		return node_len + pad_len;
122	}
123
124	return SCANNED_A_NODE;
125}
126
127/**
128 * ubifs_start_scan - create LEB scanning information at start of scan.
129 * @c: UBIFS file-system description object
130 * @lnum: logical eraseblock number
131 * @offs: offset to start at (usually zero)
132 * @sbuf: scan buffer (must be c->leb_size)
133 *
134 * This function returns the scanned information on success and a negative error
135 * code on failure.
136 */
137struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
138					int offs, void *sbuf)
139{
140	struct ubifs_scan_leb *sleb;
141	int err;
142
143	dbg_scan("scan LEB %d:%d", lnum, offs);
144
145	sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
146	if (!sleb)
147		return ERR_PTR(-ENOMEM);
148
149	sleb->lnum = lnum;
150	INIT_LIST_HEAD(&sleb->nodes);
151	sleb->buf = sbuf;
152
153	err = ubifs_leb_read(c, lnum, sbuf + offs, offs, c->leb_size - offs, 0);
154	if (err && err != -EBADMSG) {
155		ubifs_err(c, "cannot read %d bytes from LEB %d:%d, error %d",
156			  c->leb_size - offs, lnum, offs, err);
157		kfree(sleb);
158		return ERR_PTR(err);
159	}
160
161	/*
162	 * Note, we ignore integrity errors (EBASMSG) because all the nodes are
163	 * protected by CRC checksums.
164	 */
165	return sleb;
166}
167
168/**
169 * ubifs_end_scan - update LEB scanning information at end of scan.
170 * @c: UBIFS file-system description object
171 * @sleb: scanning information
172 * @lnum: logical eraseblock number
173 * @offs: offset to start at (usually zero)
174 */
175void ubifs_end_scan(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
176		    int lnum, int offs)
177{
178	lnum = lnum;
179	dbg_scan("stop scanning LEB %d at offset %d", lnum, offs);
180	ubifs_assert(offs % c->min_io_size == 0);
181
182	sleb->endpt = ALIGN(offs, c->min_io_size);
183}
184
185/**
186 * ubifs_add_snod - add a scanned node to LEB scanning information.
187 * @c: UBIFS file-system description object
188 * @sleb: scanning information
189 * @buf: buffer containing node
190 * @offs: offset of node on flash
191 *
192 * This function returns %0 on success and a negative error code on failure.
193 */
194int ubifs_add_snod(const struct ubifs_info *c, struct ubifs_scan_leb *sleb,
195		   void *buf, int offs)
196{
197	struct ubifs_ch *ch = buf;
198	struct ubifs_ino_node *ino = buf;
199	struct ubifs_scan_node *snod;
200
201	snod = kmalloc(sizeof(struct ubifs_scan_node), GFP_NOFS);
202	if (!snod)
203		return -ENOMEM;
204
205	snod->sqnum = le64_to_cpu(ch->sqnum);
206	snod->type = ch->node_type;
207	snod->offs = offs;
208	snod->len = le32_to_cpu(ch->len);
209	snod->node = buf;
210
211	switch (ch->node_type) {
212	case UBIFS_INO_NODE:
213	case UBIFS_DENT_NODE:
214	case UBIFS_XENT_NODE:
215	case UBIFS_DATA_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	default:
223		invalid_key_init(c, &snod->key);
224		break;
225	}
226	list_add_tail(&snod->list, &sleb->nodes);
227	sleb->nodes_cnt += 1;
228	return 0;
229}
230
231/**
232 * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
233 * @c: UBIFS file-system description object
234 * @lnum: LEB number of corruption
235 * @offs: offset of corruption
236 * @buf: buffer containing corruption
237 */
238void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
239			      void *buf)
240{
241	int len;
242
243	ubifs_err(c, "corruption at LEB %d:%d", lnum, offs);
244	len = c->leb_size - offs;
245	if (len > 8192)
246		len = 8192;
247	ubifs_err(c, "first %d bytes from LEB %d:%d", len, lnum, offs);
248	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 4, buf, len, 1);
249}
250
251/**
252 * ubifs_scan - scan a logical eraseblock.
253 * @c: UBIFS file-system description object
254 * @lnum: logical eraseblock number
255 * @offs: offset to start at (usually zero)
256 * @sbuf: scan buffer (must be of @c->leb_size bytes in size)
257 * @quiet: print no messages
258 *
259 * This function scans LEB number @lnum and returns complete information about
260 * its contents. Returns the scanned information in case of success and,
261 * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
262 * of failure.
263 *
264 * If @quiet is non-zero, this function does not print large and scary
265 * error messages and flash dumps in case of errors.
266 */
267struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
268				  int offs, void *sbuf, int quiet)
269{
270	void *buf = sbuf + offs;
271	int err, len = c->leb_size - offs;
272	struct ubifs_scan_leb *sleb;
273
274	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
275	if (IS_ERR(sleb))
276		return sleb;
277
278	while (len >= 8) {
279		struct ubifs_ch *ch = buf;
280		int node_len, ret;
281
282		dbg_scan("look at LEB %d:%d (%d bytes left)",
283			 lnum, offs, len);
284
285		cond_resched();
286
287		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
288		if (ret > 0) {
289			/* Padding bytes or a valid padding node */
290			offs += ret;
291			buf += ret;
292			len -= ret;
293			continue;
294		}
295
296		if (ret == SCANNED_EMPTY_SPACE)
297			/* Empty space is checked later */
298			break;
299
300		switch (ret) {
301		case SCANNED_GARBAGE:
302			ubifs_err(c, "garbage");
303			goto corrupted;
304		case SCANNED_A_NODE:
305			break;
306		case SCANNED_A_CORRUPT_NODE:
307		case SCANNED_A_BAD_PAD_NODE:
308			ubifs_err(c, "bad node");
309			goto corrupted;
310		default:
311			ubifs_err(c, "unknown");
312			err = -EINVAL;
313			goto error;
314		}
315
316		err = ubifs_add_snod(c, sleb, buf, offs);
317		if (err)
318			goto error;
319
320		node_len = ALIGN(le32_to_cpu(ch->len), 8);
321		offs += node_len;
322		buf += node_len;
323		len -= node_len;
324	}
325
326	if (offs % c->min_io_size) {
327		if (!quiet)
328			ubifs_err(c, "empty space starts at non-aligned offset %d",
329				  offs);
330		goto corrupted;
331	}
332
333	ubifs_end_scan(c, sleb, lnum, offs);
334
335	for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
336		if (*(uint32_t *)buf != 0xffffffff)
337			break;
338	for (; len; offs++, buf++, len--)
339		if (*(uint8_t *)buf != 0xff) {
340			if (!quiet)
341				ubifs_err(c, "corrupt empty space at LEB %d:%d",
342					  lnum, offs);
343			goto corrupted;
344		}
345
346	return sleb;
347
348corrupted:
349	if (!quiet) {
350		ubifs_scanned_corruption(c, lnum, offs, buf);
351		ubifs_err(c, "LEB %d scanning failed", lnum);
352	}
353	err = -EUCLEAN;
354	ubifs_scan_destroy(sleb);
355	return ERR_PTR(err);
356
357error:
358	ubifs_err(c, "LEB %d scanning failed, error %d", lnum, err);
359	ubifs_scan_destroy(sleb);
360	return ERR_PTR(err);
361}
362
363/**
364 * ubifs_scan_destroy - destroy LEB scanning information.
365 * @sleb: scanning information to free
366 */
367void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
368{
369	struct ubifs_scan_node *node;
370	struct list_head *head;
371
372	head = &sleb->nodes;
373	while (!list_empty(head)) {
374		node = list_entry(head->next, struct ubifs_scan_node, list);
375		list_del(&node->list);
376		kfree(node);
377	}
378	kfree(sleb);
379}
380