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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 | */ |
40 | static 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 | */ |
69 | int 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 | } |
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 | */ |
136 | struct 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 | */ |
175 | void 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 | */ |
194 | int 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 | */ |
236 | void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs, |
237 | void *buf) |
238 | { |
239 | int len; |
240 | |
241 | ubifs_err("corruption at LEB %d:%d", lnum, offs); |
242 | if (dbg_failure_mode) |
243 | return; |
244 | len = c->leb_size - offs; |
245 | if (len > 8192) |
246 | len = 8192; |
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 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 | struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum, |
264 | int offs, void *sbuf) |
265 | { |
266 | void *buf = sbuf + offs; |
267 | int err, len = c->leb_size - offs; |
268 | struct ubifs_scan_leb *sleb; |
269 | |
270 | sleb = ubifs_start_scan(c, lnum, offs, sbuf); |
271 | if (IS_ERR(sleb)) |
272 | return sleb; |
273 | |
274 | while (len >= 8) { |
275 | struct ubifs_ch *ch = buf; |
276 | int node_len, ret; |
277 | |
278 | dbg_scan("look at LEB %d:%d (%d bytes left)", |
279 | lnum, offs, len); |
280 | |
281 | cond_resched(); |
282 | |
283 | ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0); |
284 | if (ret > 0) { |
285 | /* Padding bytes or a valid padding node */ |
286 | offs += ret; |
287 | buf += ret; |
288 | len -= ret; |
289 | continue; |
290 | } |
291 | |
292 | if (ret == SCANNED_EMPTY_SPACE) |
293 | /* Empty space is checked later */ |
294 | break; |
295 | |
296 | switch (ret) { |
297 | case SCANNED_GARBAGE: |
298 | dbg_err("garbage"); |
299 | goto corrupted; |
300 | case SCANNED_A_NODE: |
301 | break; |
302 | case SCANNED_A_CORRUPT_NODE: |
303 | case SCANNED_A_BAD_PAD_NODE: |
304 | dbg_err("bad node"); |
305 | goto corrupted; |
306 | default: |
307 | dbg_err("unknown"); |
308 | err = -EINVAL; |
309 | goto error; |
310 | } |
311 | |
312 | err = ubifs_add_snod(c, sleb, buf, offs); |
313 | if (err) |
314 | goto error; |
315 | |
316 | node_len = ALIGN(le32_to_cpu(ch->len), 8); |
317 | offs += node_len; |
318 | buf += node_len; |
319 | len -= node_len; |
320 | } |
321 | |
322 | if (offs % c->min_io_size) { |
323 | ubifs_err("empty space starts at non-aligned offset %d", offs); |
324 | goto corrupted;; |
325 | } |
326 | |
327 | ubifs_end_scan(c, sleb, lnum, offs); |
328 | |
329 | for (; len > 4; offs += 4, buf = buf + 4, len -= 4) |
330 | if (*(uint32_t *)buf != 0xffffffff) |
331 | break; |
332 | for (; len; offs++, buf++, len--) |
333 | if (*(uint8_t *)buf != 0xff) { |
334 | ubifs_err("corrupt empty space at LEB %d:%d", |
335 | lnum, offs); |
336 | goto corrupted; |
337 | } |
338 | |
339 | return sleb; |
340 | |
341 | corrupted: |
342 | ubifs_scanned_corruption(c, lnum, offs, buf); |
343 | err = -EUCLEAN; |
344 | error: |
345 | ubifs_err("LEB %d scanning failed", lnum); |
346 | ubifs_scan_destroy(sleb); |
347 | return ERR_PTR(err); |
348 | } |
349 | |
350 | /** |
351 | * ubifs_scan_destroy - destroy LEB scanning information. |
352 | * @sleb: scanning information to free |
353 | */ |
354 | void ubifs_scan_destroy(struct ubifs_scan_leb *sleb) |
355 | { |
356 | struct ubifs_scan_node *node; |
357 | struct list_head *head; |
358 | |
359 | head = &sleb->nodes; |
360 | while (!list_empty(head)) { |
361 | node = list_entry(head->next, struct ubifs_scan_node, list); |
362 | list_del(&node->list); |
363 | kfree(node); |
364 | } |
365 | kfree(sleb); |
366 | } |
367 |
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