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("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 */ 261 struct 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; 336 337 corrupted: 338 ubifs_scanned_corruption(c, lnum, offs, buf); 339 err = -EUCLEAN; 340 error: 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 */ 350 void 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 } 363