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-rw-r--r--fs/ubifs/scan.c362
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diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
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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");
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))
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 }
115 return SCANNED_A_BAD_PAD_NODE;
116 }
117
118 dbg_scan("%d bytes padded, offset now %d",
119 pad_len, 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 %0 on success and a negative error code on failure.
135 */
136struct ubifs_scan_leb *ubifs_start_scan(const struct ubifs_info *c, int lnum,
137 int offs, void *sbuf)
138{
139 struct ubifs_scan_leb *sleb;
140 int err;
141
142 dbg_scan("scan LEB %d:%d", lnum, offs);
143
144 sleb = kzalloc(sizeof(struct ubifs_scan_leb), GFP_NOFS);
145 if (!sleb)
146 return ERR_PTR(-ENOMEM);
147
148 sleb->lnum = lnum;
149 INIT_LIST_HEAD(&sleb->nodes);
150 sleb->buf = sbuf;
151
152 err = ubi_read(c->ubi, lnum, sbuf + offs, offs, c->leb_size - offs);
153 if (err && err != -EBADMSG) {
154 ubifs_err("cannot read %d bytes from LEB %d:%d,"
155 " error %d", c->leb_size - offs, lnum, offs, err);
156 kfree(sleb);
157 return ERR_PTR(err);
158 }
159
160 if (err == -EBADMSG)
161 sleb->ecc = 1;
162
163 return sleb;
164}
165
166/**
167 * ubifs_end_scan - update LEB scanning information at end of scan.
168 * @c: UBIFS file-system description object
169 * @sleb: scanning information
170 * @lnum: logical eraseblock number
171 * @offs: offset to start at (usually zero)
172 *
173 * This function returns %0 on success and a negative error code on failure.
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 = kzalloc(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 case UBIFS_TRUN_NODE:
217 /*
218 * The key is in the same place in all keyed
219 * nodes.
220 */
221 key_read(c, &ino->key, &snod->key);
222 break;
223 }
224 list_add_tail(&snod->list, &sleb->nodes);
225 sleb->nodes_cnt += 1;
226 return 0;
227}
228
229/**
230 * ubifs_scanned_corruption - print information after UBIFS scanned corruption.
231 * @c: UBIFS file-system description object
232 * @lnum: LEB number of corruption
233 * @offs: offset of corruption
234 * @buf: buffer containing corruption
235 */
236void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
237 void *buf)
238{
239 int len;
240
241 ubifs_err("corrupted data at LEB %d:%d", lnum, offs);
242 if (dbg_failure_mode)
243 return;
244 len = c->leb_size - offs;
245 if (len > 4096)
246 len = 4096;
247 dbg_err("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 c->leb_size)
257 *
258 * This function scans LEB number @lnum and returns complete information about
259 * its contents. Returns an error code in case of failure.
260 */
261struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
262 int offs, void *sbuf)
263{
264 void *buf = sbuf + offs;
265 int err, len = c->leb_size - offs;
266 struct ubifs_scan_leb *sleb;
267
268 sleb = ubifs_start_scan(c, lnum, offs, sbuf);
269 if (IS_ERR(sleb))
270 return sleb;
271
272 while (len >= 8) {
273 struct ubifs_ch *ch = buf;
274 int node_len, ret;
275
276 dbg_scan("look at LEB %d:%d (%d bytes left)",
277 lnum, offs, len);
278
279 cond_resched();
280
281 ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
282
283 if (ret > 0) {
284 /* Padding bytes or a valid padding node */
285 offs += ret;
286 buf += ret;
287 len -= ret;
288 continue;
289 }
290
291 if (ret == SCANNED_EMPTY_SPACE)
292 /* Empty space is checked later */
293 break;
294
295 switch (ret) {
296 case SCANNED_GARBAGE:
297 dbg_err("garbage");
298 goto corrupted;
299 case SCANNED_A_NODE:
300 break;
301 case SCANNED_A_CORRUPT_NODE:
302 case SCANNED_A_BAD_PAD_NODE:
303 dbg_err("bad node");
304 goto corrupted;
305 default:
306 dbg_err("unknown");
307 goto corrupted;
308 }
309
310 err = ubifs_add_snod(c, sleb, buf, offs);
311 if (err)
312 goto error;
313
314 node_len = ALIGN(le32_to_cpu(ch->len), 8);
315 offs += node_len;
316 buf += node_len;
317 len -= node_len;
318 }
319
320 if (offs % c->min_io_size)
321 goto corrupted;
322
323 ubifs_end_scan(c, sleb, lnum, offs);
324
325 for (; len > 4; offs += 4, buf = buf + 4, len -= 4)
326 if (*(uint32_t *)buf != 0xffffffff)
327 break;
328 for (; len; offs++, buf++, len--)
329 if (*(uint8_t *)buf != 0xff) {
330 ubifs_err("corrupt empty space at LEB %d:%d",
331 lnum, offs);
332 goto corrupted;
333 }
334
335 return sleb;
336
337corrupted:
338 ubifs_scanned_corruption(c, lnum, offs, buf);
339 err = -EUCLEAN;
340error:
341 ubifs_err("LEB %d scanning failed", lnum);
342 ubifs_scan_destroy(sleb);
343 return ERR_PTR(err);
344}
345
346/**
347 * ubifs_scan_destroy - destroy LEB scanning information.
348 * @sleb: scanning information to free
349 */
350void ubifs_scan_destroy(struct ubifs_scan_leb *sleb)
351{
352 struct ubifs_scan_node *node;
353 struct list_head *head;
354
355 head = &sleb->nodes;
356 while (!list_empty(head)) {
357 node = list_entry(head->next, struct ubifs_scan_node, list);
358 list_del(&node->list);
359 kfree(node);
360 }
361 kfree(sleb);
362}