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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * index.c - NTFS kernel index handling. Part of the Linux-NTFS project.
3 *
Anton Altaparmakov442d2072005-05-27 16:42:56 +01004 * Copyright (c) 2004-2005 Anton Altaparmakov
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
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 "aops.h"
23#include "collate.h"
24#include "debug.h"
25#include "index.h"
26#include "ntfs.h"
27
28/**
29 * ntfs_index_ctx_get - allocate and initialize a new index context
30 * @idx_ni: ntfs index inode with which to initialize the context
31 *
32 * Allocate a new index context, initialize it with @idx_ni and return it.
33 * Return NULL if allocation failed.
34 *
35 * Locking: Caller must hold i_sem on the index inode.
36 */
37ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
38{
39 ntfs_index_context *ictx;
40
41 ictx = kmem_cache_alloc(ntfs_index_ctx_cache, SLAB_NOFS);
Anton Altaparmakov442d2072005-05-27 16:42:56 +010042 if (ictx)
43 *ictx = (ntfs_index_context){ .idx_ni = idx_ni };
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 return ictx;
45}
46
47/**
48 * ntfs_index_ctx_put - release an index context
49 * @ictx: index context to free
50 *
51 * Release the index context @ictx, releasing all associated resources.
52 *
53 * Locking: Caller must hold i_sem on the index inode.
54 */
55void ntfs_index_ctx_put(ntfs_index_context *ictx)
56{
57 if (ictx->entry) {
58 if (ictx->is_in_root) {
59 if (ictx->actx)
60 ntfs_attr_put_search_ctx(ictx->actx);
61 if (ictx->base_ni)
62 unmap_mft_record(ictx->base_ni);
63 } else {
64 struct page *page = ictx->page;
65 if (page) {
66 BUG_ON(!PageLocked(page));
67 unlock_page(page);
68 ntfs_unmap_page(page);
69 }
70 }
71 }
72 kmem_cache_free(ntfs_index_ctx_cache, ictx);
73 return;
74}
75
76/**
77 * ntfs_index_lookup - find a key in an index and return its index entry
78 * @key: [IN] key for which to search in the index
79 * @key_len: [IN] length of @key in bytes
80 * @ictx: [IN/OUT] context describing the index and the returned entry
81 *
82 * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
83 * call to ntfs_index_ctx_get().
84 *
85 * Look for the @key in the index specified by the index lookup context @ictx.
86 * ntfs_index_lookup() walks the contents of the index looking for the @key.
87 *
88 * If the @key is found in the index, 0 is returned and @ictx is setup to
89 * describe the index entry containing the matching @key. @ictx->entry is the
90 * index entry and @ictx->data and @ictx->data_len are the index entry data and
91 * its length in bytes, respectively.
92 *
93 * If the @key is not found in the index, -ENOENT is returned and @ictx is
94 * setup to describe the index entry whose key collates immediately after the
95 * search @key, i.e. this is the position in the index at which an index entry
96 * with a key of @key would need to be inserted.
97 *
98 * If an error occurs return the negative error code and @ictx is left
99 * untouched.
100 *
101 * When finished with the entry and its data, call ntfs_index_ctx_put() to free
102 * the context and other associated resources.
103 *
104 * If the index entry was modified, call flush_dcache_index_entry_page()
105 * immediately after the modification and either ntfs_index_entry_mark_dirty()
106 * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
107 * ensure that the changes are written to disk.
108 *
109 * Locking: - Caller must hold i_sem on the index inode.
110 * - Each page cache page in the index allocation mapping must be
111 * locked whilst being accessed otherwise we may find a corrupt
112 * page due to it being under ->writepage at the moment which
113 * applies the mst protection fixups before writing out and then
114 * removes them again after the write is complete after which it
115 * unlocks the page.
116 */
117int ntfs_index_lookup(const void *key, const int key_len,
118 ntfs_index_context *ictx)
119{
120 VCN vcn, old_vcn;
121 ntfs_inode *idx_ni = ictx->idx_ni;
122 ntfs_volume *vol = idx_ni->vol;
123 struct super_block *sb = vol->sb;
124 ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
125 MFT_RECORD *m;
126 INDEX_ROOT *ir;
127 INDEX_ENTRY *ie;
128 INDEX_ALLOCATION *ia;
129 u8 *index_end, *kaddr;
130 ntfs_attr_search_ctx *actx;
131 struct address_space *ia_mapping;
132 struct page *page;
133 int rc, err = 0;
134
135 ntfs_debug("Entering.");
136 BUG_ON(!NInoAttr(idx_ni));
137 BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
138 BUG_ON(idx_ni->nr_extents != -1);
139 BUG_ON(!base_ni);
140 BUG_ON(!key);
141 BUG_ON(key_len <= 0);
142 if (!ntfs_is_collation_rule_supported(
143 idx_ni->itype.index.collation_rule)) {
144 ntfs_error(sb, "Index uses unsupported collation rule 0x%x. "
145 "Aborting lookup.", le32_to_cpu(
146 idx_ni->itype.index.collation_rule));
147 return -EOPNOTSUPP;
148 }
149 /* Get hold of the mft record for the index inode. */
150 m = map_mft_record(base_ni);
151 if (IS_ERR(m)) {
152 ntfs_error(sb, "map_mft_record() failed with error code %ld.",
153 -PTR_ERR(m));
154 return PTR_ERR(m);
155 }
156 actx = ntfs_attr_get_search_ctx(base_ni, m);
157 if (unlikely(!actx)) {
158 err = -ENOMEM;
159 goto err_out;
160 }
161 /* Find the index root attribute in the mft record. */
162 err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
163 CASE_SENSITIVE, 0, NULL, 0, actx);
164 if (unlikely(err)) {
165 if (err == -ENOENT) {
166 ntfs_error(sb, "Index root attribute missing in inode "
167 "0x%lx.", idx_ni->mft_no);
168 err = -EIO;
169 }
170 goto err_out;
171 }
172 /* Get to the index root value (it has been verified in read_inode). */
173 ir = (INDEX_ROOT*)((u8*)actx->attr +
174 le16_to_cpu(actx->attr->data.resident.value_offset));
175 index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
176 /* The first index entry. */
177 ie = (INDEX_ENTRY*)((u8*)&ir->index +
178 le32_to_cpu(ir->index.entries_offset));
179 /*
180 * Loop until we exceed valid memory (corruption case) or until we
181 * reach the last entry.
182 */
183 for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
184 /* Bounds checks. */
185 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
186 sizeof(INDEX_ENTRY_HEADER) > index_end ||
187 (u8*)ie + le16_to_cpu(ie->length) > index_end)
188 goto idx_err_out;
189 /*
190 * The last entry cannot contain a key. It can however contain
191 * a pointer to a child node in the B+tree so we just break out.
192 */
193 if (ie->flags & INDEX_ENTRY_END)
194 break;
195 /* Further bounds checks. */
196 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
197 le16_to_cpu(ie->key_length) >
198 le16_to_cpu(ie->data.vi.data_offset) ||
199 (u32)le16_to_cpu(ie->data.vi.data_offset) +
200 le16_to_cpu(ie->data.vi.data_length) >
201 le16_to_cpu(ie->length))
202 goto idx_err_out;
203 /* If the keys match perfectly, we setup @ictx and return 0. */
204 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
205 &ie->key, key_len)) {
206ir_done:
207 ictx->is_in_root = TRUE;
Anton Altaparmakov8e08ceae2005-09-08 20:29:50 +0100208 ictx->ir = ir;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 ictx->actx = actx;
210 ictx->base_ni = base_ni;
211 ictx->ia = NULL;
212 ictx->page = NULL;
213done:
214 ictx->entry = ie;
215 ictx->data = (u8*)ie +
216 le16_to_cpu(ie->data.vi.data_offset);
217 ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
218 ntfs_debug("Done.");
219 return err;
220 }
221 /*
222 * Not a perfect match, need to do full blown collation so we
223 * know which way in the B+tree we have to go.
224 */
225 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
226 key_len, &ie->key, le16_to_cpu(ie->key_length));
227 /*
228 * If @key collates before the key of the current entry, there
229 * is definitely no such key in this index but we might need to
230 * descend into the B+tree so we just break out of the loop.
231 */
232 if (rc == -1)
233 break;
234 /*
235 * A match should never happen as the memcmp() call should have
236 * cought it, but we still treat it correctly.
237 */
238 if (!rc)
239 goto ir_done;
240 /* The keys are not equal, continue the search. */
241 }
242 /*
243 * We have finished with this index without success. Check for the
244 * presence of a child node and if not present setup @ictx and return
245 * -ENOENT.
246 */
247 if (!(ie->flags & INDEX_ENTRY_NODE)) {
248 ntfs_debug("Entry not found.");
249 err = -ENOENT;
250 goto ir_done;
251 } /* Child node present, descend into it. */
252 /* Consistency check: Verify that an index allocation exists. */
253 if (!NInoIndexAllocPresent(idx_ni)) {
254 ntfs_error(sb, "No index allocation attribute but index entry "
255 "requires one. Inode 0x%lx is corrupt or "
256 "driver bug.", idx_ni->mft_no);
257 goto err_out;
258 }
259 /* Get the starting vcn of the index_block holding the child node. */
260 vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
261 ia_mapping = VFS_I(idx_ni)->i_mapping;
262 /*
263 * We are done with the index root and the mft record. Release them,
264 * otherwise we deadlock with ntfs_map_page().
265 */
266 ntfs_attr_put_search_ctx(actx);
267 unmap_mft_record(base_ni);
268 m = NULL;
269 actx = NULL;
270descend_into_child_node:
271 /*
272 * Convert vcn to index into the index allocation attribute in units
273 * of PAGE_CACHE_SIZE and map the page cache page, reading it from
274 * disk if necessary.
275 */
276 page = ntfs_map_page(ia_mapping, vcn <<
277 idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
278 if (IS_ERR(page)) {
279 ntfs_error(sb, "Failed to map index page, error %ld.",
280 -PTR_ERR(page));
281 err = PTR_ERR(page);
282 goto err_out;
283 }
284 lock_page(page);
285 kaddr = (u8*)page_address(page);
286fast_descend_into_child_node:
287 /* Get to the index allocation block. */
288 ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
289 idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
290 /* Bounds checks. */
291 if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
292 ntfs_error(sb, "Out of bounds check failed. Corrupt inode "
293 "0x%lx or driver bug.", idx_ni->mft_no);
294 goto unm_err_out;
295 }
296 /* Catch multi sector transfer fixup errors. */
297 if (unlikely(!ntfs_is_indx_record(ia->magic))) {
298 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt. "
299 "Corrupt inode 0x%lx. Run chkdsk.",
300 (long long)vcn, idx_ni->mft_no);
301 goto unm_err_out;
302 }
303 if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
304 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
305 "different from expected VCN (0x%llx). Inode "
306 "0x%lx is corrupt or driver bug.",
307 (unsigned long long)
308 sle64_to_cpu(ia->index_block_vcn),
309 (unsigned long long)vcn, idx_ni->mft_no);
310 goto unm_err_out;
311 }
312 if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
313 idx_ni->itype.index.block_size) {
314 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
315 "a size (%u) differing from the index "
316 "specified size (%u). Inode is corrupt or "
317 "driver bug.", (unsigned long long)vcn,
318 idx_ni->mft_no,
319 le32_to_cpu(ia->index.allocated_size) + 0x18,
320 idx_ni->itype.index.block_size);
321 goto unm_err_out;
322 }
323 index_end = (u8*)ia + idx_ni->itype.index.block_size;
324 if (index_end > kaddr + PAGE_CACHE_SIZE) {
325 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
326 "crosses page boundary. Impossible! Cannot "
327 "access! This is probably a bug in the "
328 "driver.", (unsigned long long)vcn,
329 idx_ni->mft_no);
330 goto unm_err_out;
331 }
332 index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
333 if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
334 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
335 "0x%lx exceeds maximum size.",
336 (unsigned long long)vcn, idx_ni->mft_no);
337 goto unm_err_out;
338 }
339 /* The first index entry. */
340 ie = (INDEX_ENTRY*)((u8*)&ia->index +
341 le32_to_cpu(ia->index.entries_offset));
342 /*
343 * Iterate similar to above big loop but applied to index buffer, thus
344 * loop until we exceed valid memory (corruption case) or until we
345 * reach the last entry.
346 */
347 for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
348 /* Bounds checks. */
349 if ((u8*)ie < (u8*)ia || (u8*)ie +
350 sizeof(INDEX_ENTRY_HEADER) > index_end ||
351 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
352 ntfs_error(sb, "Index entry out of bounds in inode "
353 "0x%lx.", idx_ni->mft_no);
354 goto unm_err_out;
355 }
356 /*
357 * The last entry cannot contain a key. It can however contain
358 * a pointer to a child node in the B+tree so we just break out.
359 */
360 if (ie->flags & INDEX_ENTRY_END)
361 break;
362 /* Further bounds checks. */
363 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
364 le16_to_cpu(ie->key_length) >
365 le16_to_cpu(ie->data.vi.data_offset) ||
366 (u32)le16_to_cpu(ie->data.vi.data_offset) +
367 le16_to_cpu(ie->data.vi.data_length) >
368 le16_to_cpu(ie->length)) {
369 ntfs_error(sb, "Index entry out of bounds in inode "
370 "0x%lx.", idx_ni->mft_no);
371 goto unm_err_out;
372 }
373 /* If the keys match perfectly, we setup @ictx and return 0. */
374 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
375 &ie->key, key_len)) {
376ia_done:
377 ictx->is_in_root = FALSE;
378 ictx->actx = NULL;
379 ictx->base_ni = NULL;
380 ictx->ia = ia;
381 ictx->page = page;
382 goto done;
383 }
384 /*
385 * Not a perfect match, need to do full blown collation so we
386 * know which way in the B+tree we have to go.
387 */
388 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
389 key_len, &ie->key, le16_to_cpu(ie->key_length));
390 /*
391 * If @key collates before the key of the current entry, there
392 * is definitely no such key in this index but we might need to
393 * descend into the B+tree so we just break out of the loop.
394 */
395 if (rc == -1)
396 break;
397 /*
398 * A match should never happen as the memcmp() call should have
399 * cought it, but we still treat it correctly.
400 */
401 if (!rc)
402 goto ia_done;
403 /* The keys are not equal, continue the search. */
404 }
405 /*
406 * We have finished with this index buffer without success. Check for
407 * the presence of a child node and if not present return -ENOENT.
408 */
409 if (!(ie->flags & INDEX_ENTRY_NODE)) {
410 ntfs_debug("Entry not found.");
411 err = -ENOENT;
412 goto ia_done;
413 }
414 if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
415 ntfs_error(sb, "Index entry with child node found in a leaf "
416 "node in inode 0x%lx.", idx_ni->mft_no);
417 goto unm_err_out;
418 }
419 /* Child node present, descend into it. */
420 old_vcn = vcn;
421 vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
422 if (vcn >= 0) {
423 /*
424 * If vcn is in the same page cache page as old_vcn we recycle
425 * the mapped page.
426 */
427 if (old_vcn << vol->cluster_size_bits >>
428 PAGE_CACHE_SHIFT == vcn <<
429 vol->cluster_size_bits >>
430 PAGE_CACHE_SHIFT)
431 goto fast_descend_into_child_node;
432 unlock_page(page);
433 ntfs_unmap_page(page);
434 goto descend_into_child_node;
435 }
436 ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
437 idx_ni->mft_no);
438unm_err_out:
439 unlock_page(page);
440 ntfs_unmap_page(page);
441err_out:
442 if (!err)
443 err = -EIO;
444 if (actx)
445 ntfs_attr_put_search_ctx(actx);
446 if (m)
447 unmap_mft_record(base_ni);
448 return err;
449idx_err_out:
450 ntfs_error(sb, "Corrupt index. Aborting lookup.");
451 goto err_out;
452}