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TOMOYO Linux Cross Reference
Linux/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  */
 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 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  */
137 struct 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  */
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 = 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  */
238 void 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  */
267 struct 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 
348 corrupted:
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 
357 error:
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  */
367 void 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 

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