Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/ntfs/index.c
Version:
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1 /* 2 * index.c - NTFS kernel index handling. Part of the Linux-NTFS project. 3 * 4 * Copyright (c) 2004-2005 Anton Altaparmakov 5 * 6 * This program/include file is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as published 8 * by the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program/include file is distributed in the hope that it will be 12 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty 13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program (in the main directory of the Linux-NTFS 18 * distribution in the file COPYING); if not, write to the Free Software 19 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/slab.h> 23 24 #include "aops.h" 25 #include "collate.h" 26 #include "debug.h" 27 #include "index.h" 28 #include "ntfs.h" 29 30 /** 31 * ntfs_index_ctx_get - allocate and initialize a new index context 32 * @idx_ni: ntfs index inode with which to initialize the context 33 * 34 * Allocate a new index context, initialize it with @idx_ni and return it. 35 * Return NULL if allocation failed. 36 * 37 * Locking: Caller must hold i_mutex on the index inode. 38 */ 39 ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni) 40 { 41 ntfs_index_context *ictx; 42 43 ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS); 44 if (ictx) 45 *ictx = (ntfs_index_context){ .idx_ni = idx_ni }; 46 return ictx; 47 } 48 49 /** 50 * ntfs_index_ctx_put - release an index context 51 * @ictx: index context to free 52 * 53 * Release the index context @ictx, releasing all associated resources. 54 * 55 * Locking: Caller must hold i_mutex on the index inode. 56 */ 57 void ntfs_index_ctx_put(ntfs_index_context *ictx) 58 { 59 if (ictx->entry) { 60 if (ictx->is_in_root) { 61 if (ictx->actx) 62 ntfs_attr_put_search_ctx(ictx->actx); 63 if (ictx->base_ni) 64 unmap_mft_record(ictx->base_ni); 65 } else { 66 struct page *page = ictx->page; 67 if (page) { 68 BUG_ON(!PageLocked(page)); 69 unlock_page(page); 70 ntfs_unmap_page(page); 71 } 72 } 73 } 74 kmem_cache_free(ntfs_index_ctx_cache, ictx); 75 return; 76 } 77 78 /** 79 * ntfs_index_lookup - find a key in an index and return its index entry 80 * @key: [IN] key for which to search in the index 81 * @key_len: [IN] length of @key in bytes 82 * @ictx: [IN/OUT] context describing the index and the returned entry 83 * 84 * Before calling ntfs_index_lookup(), @ictx must have been obtained from a 85 * call to ntfs_index_ctx_get(). 86 * 87 * Look for the @key in the index specified by the index lookup context @ictx. 88 * ntfs_index_lookup() walks the contents of the index looking for the @key. 89 * 90 * If the @key is found in the index, 0 is returned and @ictx is setup to 91 * describe the index entry containing the matching @key. @ictx->entry is the 92 * index entry and @ictx->data and @ictx->data_len are the index entry data and 93 * its length in bytes, respectively. 94 * 95 * If the @key is not found in the index, -ENOENT is returned and @ictx is 96 * setup to describe the index entry whose key collates immediately after the 97 * search @key, i.e. this is the position in the index at which an index entry 98 * with a key of @key would need to be inserted. 99 * 100 * If an error occurs return the negative error code and @ictx is left 101 * untouched. 102 * 103 * When finished with the entry and its data, call ntfs_index_ctx_put() to free 104 * the context and other associated resources. 105 * 106 * If the index entry was modified, call flush_dcache_index_entry_page() 107 * immediately after the modification and either ntfs_index_entry_mark_dirty() 108 * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to 109 * ensure that the changes are written to disk. 110 * 111 * Locking: - Caller must hold i_mutex on the index inode. 112 * - Each page cache page in the index allocation mapping must be 113 * locked whilst being accessed otherwise we may find a corrupt 114 * page due to it being under ->writepage at the moment which 115 * applies the mst protection fixups before writing out and then 116 * removes them again after the write is complete after which it 117 * unlocks the page. 118 */ 119 int ntfs_index_lookup(const void *key, const int key_len, 120 ntfs_index_context *ictx) 121 { 122 VCN vcn, old_vcn; 123 ntfs_inode *idx_ni = ictx->idx_ni; 124 ntfs_volume *vol = idx_ni->vol; 125 struct super_block *sb = vol->sb; 126 ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino; 127 MFT_RECORD *m; 128 INDEX_ROOT *ir; 129 INDEX_ENTRY *ie; 130 INDEX_ALLOCATION *ia; 131 u8 *index_end, *kaddr; 132 ntfs_attr_search_ctx *actx; 133 struct address_space *ia_mapping; 134 struct page *page; 135 int rc, err = 0; 136 137 ntfs_debug("Entering."); 138 BUG_ON(!NInoAttr(idx_ni)); 139 BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION); 140 BUG_ON(idx_ni->nr_extents != -1); 141 BUG_ON(!base_ni); 142 BUG_ON(!key); 143 BUG_ON(key_len <= 0); 144 if (!ntfs_is_collation_rule_supported( 145 idx_ni->itype.index.collation_rule)) { 146 ntfs_error(sb, "Index uses unsupported collation rule 0x%x. " 147 "Aborting lookup.", le32_to_cpu( 148 idx_ni->itype.index.collation_rule)); 149 return -EOPNOTSUPP; 150 } 151 /* Get hold of the mft record for the index inode. */ 152 m = map_mft_record(base_ni); 153 if (IS_ERR(m)) { 154 ntfs_error(sb, "map_mft_record() failed with error code %ld.", 155 -PTR_ERR(m)); 156 return PTR_ERR(m); 157 } 158 actx = ntfs_attr_get_search_ctx(base_ni, m); 159 if (unlikely(!actx)) { 160 err = -ENOMEM; 161 goto err_out; 162 } 163 /* Find the index root attribute in the mft record. */ 164 err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len, 165 CASE_SENSITIVE, 0, NULL, 0, actx); 166 if (unlikely(err)) { 167 if (err == -ENOENT) { 168 ntfs_error(sb, "Index root attribute missing in inode " 169 "0x%lx.", idx_ni->mft_no); 170 err = -EIO; 171 } 172 goto err_out; 173 } 174 /* Get to the index root value (it has been verified in read_inode). */ 175 ir = (INDEX_ROOT*)((u8*)actx->attr + 176 le16_to_cpu(actx->attr->data.resident.value_offset)); 177 index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length); 178 /* The first index entry. */ 179 ie = (INDEX_ENTRY*)((u8*)&ir->index + 180 le32_to_cpu(ir->index.entries_offset)); 181 /* 182 * Loop until we exceed valid memory (corruption case) or until we 183 * reach the last entry. 184 */ 185 for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { 186 /* Bounds checks. */ 187 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie + 188 sizeof(INDEX_ENTRY_HEADER) > index_end || 189 (u8*)ie + le16_to_cpu(ie->length) > index_end) 190 goto idx_err_out; 191 /* 192 * The last entry cannot contain a key. It can however contain 193 * a pointer to a child node in the B+tree so we just break out. 194 */ 195 if (ie->flags & INDEX_ENTRY_END) 196 break; 197 /* Further bounds checks. */ 198 if ((u32)sizeof(INDEX_ENTRY_HEADER) + 199 le16_to_cpu(ie->key_length) > 200 le16_to_cpu(ie->data.vi.data_offset) || 201 (u32)le16_to_cpu(ie->data.vi.data_offset) + 202 le16_to_cpu(ie->data.vi.data_length) > 203 le16_to_cpu(ie->length)) 204 goto idx_err_out; 205 /* If the keys match perfectly, we setup @ictx and return 0. */ 206 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, 207 &ie->key, key_len)) { 208 ir_done: 209 ictx->is_in_root = true; 210 ictx->ir = ir; 211 ictx->actx = actx; 212 ictx->base_ni = base_ni; 213 ictx->ia = NULL; 214 ictx->page = NULL; 215 done: 216 ictx->entry = ie; 217 ictx->data = (u8*)ie + 218 le16_to_cpu(ie->data.vi.data_offset); 219 ictx->data_len = le16_to_cpu(ie->data.vi.data_length); 220 ntfs_debug("Done."); 221 return err; 222 } 223 /* 224 * Not a perfect match, need to do full blown collation so we 225 * know which way in the B+tree we have to go. 226 */ 227 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, 228 key_len, &ie->key, le16_to_cpu(ie->key_length)); 229 /* 230 * If @key collates before the key of the current entry, there 231 * is definitely no such key in this index but we might need to 232 * descend into the B+tree so we just break out of the loop. 233 */ 234 if (rc == -1) 235 break; 236 /* 237 * A match should never happen as the memcmp() call should have 238 * cought it, but we still treat it correctly. 239 */ 240 if (!rc) 241 goto ir_done; 242 /* The keys are not equal, continue the search. */ 243 } 244 /* 245 * We have finished with this index without success. Check for the 246 * presence of a child node and if not present setup @ictx and return 247 * -ENOENT. 248 */ 249 if (!(ie->flags & INDEX_ENTRY_NODE)) { 250 ntfs_debug("Entry not found."); 251 err = -ENOENT; 252 goto ir_done; 253 } /* Child node present, descend into it. */ 254 /* Consistency check: Verify that an index allocation exists. */ 255 if (!NInoIndexAllocPresent(idx_ni)) { 256 ntfs_error(sb, "No index allocation attribute but index entry " 257 "requires one. Inode 0x%lx is corrupt or " 258 "driver bug.", idx_ni->mft_no); 259 goto err_out; 260 } 261 /* Get the starting vcn of the index_block holding the child node. */ 262 vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); 263 ia_mapping = VFS_I(idx_ni)->i_mapping; 264 /* 265 * We are done with the index root and the mft record. Release them, 266 * otherwise we deadlock with ntfs_map_page(). 267 */ 268 ntfs_attr_put_search_ctx(actx); 269 unmap_mft_record(base_ni); 270 m = NULL; 271 actx = NULL; 272 descend_into_child_node: 273 /* 274 * Convert vcn to index into the index allocation attribute in units 275 * of PAGE_CACHE_SIZE and map the page cache page, reading it from 276 * disk if necessary. 277 */ 278 page = ntfs_map_page(ia_mapping, vcn << 279 idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT); 280 if (IS_ERR(page)) { 281 ntfs_error(sb, "Failed to map index page, error %ld.", 282 -PTR_ERR(page)); 283 err = PTR_ERR(page); 284 goto err_out; 285 } 286 lock_page(page); 287 kaddr = (u8*)page_address(page); 288 fast_descend_into_child_node: 289 /* Get to the index allocation block. */ 290 ia = (INDEX_ALLOCATION*)(kaddr + ((vcn << 291 idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK)); 292 /* Bounds checks. */ 293 if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) { 294 ntfs_error(sb, "Out of bounds check failed. Corrupt inode " 295 "0x%lx or driver bug.", idx_ni->mft_no); 296 goto unm_err_out; 297 } 298 /* Catch multi sector transfer fixup errors. */ 299 if (unlikely(!ntfs_is_indx_record(ia->magic))) { 300 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt. " 301 "Corrupt inode 0x%lx. Run chkdsk.", 302 (long long)vcn, idx_ni->mft_no); 303 goto unm_err_out; 304 } 305 if (sle64_to_cpu(ia->index_block_vcn) != vcn) { 306 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is " 307 "different from expected VCN (0x%llx). Inode " 308 "0x%lx is corrupt or driver bug.", 309 (unsigned long long) 310 sle64_to_cpu(ia->index_block_vcn), 311 (unsigned long long)vcn, idx_ni->mft_no); 312 goto unm_err_out; 313 } 314 if (le32_to_cpu(ia->index.allocated_size) + 0x18 != 315 idx_ni->itype.index.block_size) { 316 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has " 317 "a size (%u) differing from the index " 318 "specified size (%u). Inode is corrupt or " 319 "driver bug.", (unsigned long long)vcn, 320 idx_ni->mft_no, 321 le32_to_cpu(ia->index.allocated_size) + 0x18, 322 idx_ni->itype.index.block_size); 323 goto unm_err_out; 324 } 325 index_end = (u8*)ia + idx_ni->itype.index.block_size; 326 if (index_end > kaddr + PAGE_CACHE_SIZE) { 327 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx " 328 "crosses page boundary. Impossible! Cannot " 329 "access! This is probably a bug in the " 330 "driver.", (unsigned long long)vcn, 331 idx_ni->mft_no); 332 goto unm_err_out; 333 } 334 index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length); 335 if (index_end > (u8*)ia + idx_ni->itype.index.block_size) { 336 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode " 337 "0x%lx exceeds maximum size.", 338 (unsigned long long)vcn, idx_ni->mft_no); 339 goto unm_err_out; 340 } 341 /* The first index entry. */ 342 ie = (INDEX_ENTRY*)((u8*)&ia->index + 343 le32_to_cpu(ia->index.entries_offset)); 344 /* 345 * Iterate similar to above big loop but applied to index buffer, thus 346 * loop until we exceed valid memory (corruption case) or until we 347 * reach the last entry. 348 */ 349 for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { 350 /* Bounds checks. */ 351 if ((u8*)ie < (u8*)ia || (u8*)ie + 352 sizeof(INDEX_ENTRY_HEADER) > index_end || 353 (u8*)ie + le16_to_cpu(ie->length) > index_end) { 354 ntfs_error(sb, "Index entry out of bounds in inode " 355 "0x%lx.", idx_ni->mft_no); 356 goto unm_err_out; 357 } 358 /* 359 * The last entry cannot contain a key. It can however contain 360 * a pointer to a child node in the B+tree so we just break out. 361 */ 362 if (ie->flags & INDEX_ENTRY_END) 363 break; 364 /* Further bounds checks. */ 365 if ((u32)sizeof(INDEX_ENTRY_HEADER) + 366 le16_to_cpu(ie->key_length) > 367 le16_to_cpu(ie->data.vi.data_offset) || 368 (u32)le16_to_cpu(ie->data.vi.data_offset) + 369 le16_to_cpu(ie->data.vi.data_length) > 370 le16_to_cpu(ie->length)) { 371 ntfs_error(sb, "Index entry out of bounds in inode " 372 "0x%lx.", idx_ni->mft_no); 373 goto unm_err_out; 374 } 375 /* If the keys match perfectly, we setup @ictx and return 0. */ 376 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, 377 &ie->key, key_len)) { 378 ia_done: 379 ictx->is_in_root = false; 380 ictx->actx = NULL; 381 ictx->base_ni = NULL; 382 ictx->ia = ia; 383 ictx->page = page; 384 goto done; 385 } 386 /* 387 * Not a perfect match, need to do full blown collation so we 388 * know which way in the B+tree we have to go. 389 */ 390 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, 391 key_len, &ie->key, le16_to_cpu(ie->key_length)); 392 /* 393 * If @key collates before the key of the current entry, there 394 * is definitely no such key in this index but we might need to 395 * descend into the B+tree so we just break out of the loop. 396 */ 397 if (rc == -1) 398 break; 399 /* 400 * A match should never happen as the memcmp() call should have 401 * cought it, but we still treat it correctly. 402 */ 403 if (!rc) 404 goto ia_done; 405 /* The keys are not equal, continue the search. */ 406 } 407 /* 408 * We have finished with this index buffer without success. Check for 409 * the presence of a child node and if not present return -ENOENT. 410 */ 411 if (!(ie->flags & INDEX_ENTRY_NODE)) { 412 ntfs_debug("Entry not found."); 413 err = -ENOENT; 414 goto ia_done; 415 } 416 if ((ia->index.flags & NODE_MASK) == LEAF_NODE) { 417 ntfs_error(sb, "Index entry with child node found in a leaf " 418 "node in inode 0x%lx.", idx_ni->mft_no); 419 goto unm_err_out; 420 } 421 /* Child node present, descend into it. */ 422 old_vcn = vcn; 423 vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); 424 if (vcn >= 0) { 425 /* 426 * If vcn is in the same page cache page as old_vcn we recycle 427 * the mapped page. 428 */ 429 if (old_vcn << vol->cluster_size_bits >> 430 PAGE_CACHE_SHIFT == vcn << 431 vol->cluster_size_bits >> 432 PAGE_CACHE_SHIFT) 433 goto fast_descend_into_child_node; 434 unlock_page(page); 435 ntfs_unmap_page(page); 436 goto descend_into_child_node; 437 } 438 ntfs_error(sb, "Negative child node vcn in inode 0x%lx.", 439 idx_ni->mft_no); 440 unm_err_out: 441 unlock_page(page); 442 ntfs_unmap_page(page); 443 err_out: 444 if (!err) 445 err = -EIO; 446 if (actx) 447 ntfs_attr_put_search_ctx(actx); 448 if (m) 449 unmap_mft_record(base_ni); 450 return err; 451 idx_err_out: 452 ntfs_error(sb, "Corrupt index. Aborting lookup."); 453 goto err_out; 454 }
Cache object: 639608b28ff6a6996fb84164943df43c
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