2 * index.c - NTFS kernel index handling. Part of the Linux-NTFS project.
4 * Copyright (c) 2004-2005 Anton Altaparmakov
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.
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.
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
22 #include <linux/slab.h>
31 * ntfs_index_ctx_get - allocate and initialize a new index context
32 * @idx_ni: ntfs index inode with which to initialize the context
34 * Allocate a new index context, initialize it with @idx_ni and return it.
35 * Return NULL if allocation failed.
37 * Locking: Caller must hold i_mutex on the index inode.
39 ntfs_index_context
*ntfs_index_ctx_get(ntfs_inode
*idx_ni
)
41 ntfs_index_context
*ictx
;
43 ictx
= kmem_cache_alloc(ntfs_index_ctx_cache
, GFP_NOFS
);
45 *ictx
= (ntfs_index_context
){ .idx_ni
= idx_ni
};
50 * ntfs_index_ctx_put - release an index context
51 * @ictx: index context to free
53 * Release the index context @ictx, releasing all associated resources.
55 * Locking: Caller must hold i_mutex on the index inode.
57 void ntfs_index_ctx_put(ntfs_index_context
*ictx
)
60 if (ictx
->is_in_root
) {
62 ntfs_attr_put_search_ctx(ictx
->actx
);
64 unmap_mft_record(ictx
->base_ni
);
66 struct page
*page
= ictx
->page
;
68 BUG_ON(!PageLocked(page
));
70 ntfs_unmap_page(page
);
74 kmem_cache_free(ntfs_index_ctx_cache
, ictx
);
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
84 * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
85 * call to ntfs_index_ctx_get().
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.
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.
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.
100 * If an error occurs return the negative error code and @ictx is left
103 * When finished with the entry and its data, call ntfs_index_ctx_put() to free
104 * the context and other associated resources.
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.
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
119 int ntfs_index_lookup(const void *key
, const int key_len
,
120 ntfs_index_context
*ictx
)
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
;
130 INDEX_ALLOCATION
*ia
;
131 u8
*index_end
, *kaddr
;
132 ntfs_attr_search_ctx
*actx
;
133 struct address_space
*ia_mapping
;
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);
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
));
151 /* Get hold of the mft record for the index inode. */
152 m
= map_mft_record(base_ni
);
154 ntfs_error(sb
, "map_mft_record() failed with error code %ld.",
158 actx
= ntfs_attr_get_search_ctx(base_ni
, m
);
159 if (unlikely(!actx
)) {
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
);
167 if (err
== -ENOENT
) {
168 ntfs_error(sb
, "Index root attribute missing in inode "
169 "0x%lx.", idx_ni
->mft_no
);
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
));
182 * Loop until we exceed valid memory (corruption case) or until we
183 * reach the last entry.
185 for (;; ie
= (INDEX_ENTRY
*)((u8
*)ie
+ le16_to_cpu(ie
->length
))) {
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
)
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.
195 if (ie
->flags
& INDEX_ENTRY_END
)
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
))
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
)) {
209 ictx
->is_in_root
= true;
212 ictx
->base_ni
= base_ni
;
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
);
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.
227 rc
= ntfs_collate(vol
, idx_ni
->itype
.index
.collation_rule
, key
,
228 key_len
, &ie
->key
, le16_to_cpu(ie
->key_length
));
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.
237 * A match should never happen as the memcmp() call should have
238 * cought it, but we still treat it correctly.
242 /* The keys are not equal, continue the search. */
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
249 if (!(ie
->flags
& INDEX_ENTRY_NODE
)) {
250 ntfs_debug("Entry not found.");
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
);
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
;
265 * We are done with the index root and the mft record. Release them,
266 * otherwise we deadlock with ntfs_map_page().
268 ntfs_attr_put_search_ctx(actx
);
269 unmap_mft_record(base_ni
);
272 descend_into_child_node
:
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
278 page
= ntfs_map_page(ia_mapping
, vcn
<<
279 idx_ni
->itype
.index
.vcn_size_bits
>> PAGE_CACHE_SHIFT
);
281 ntfs_error(sb
, "Failed to map index page, error %ld.",
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
));
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
);
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
);
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.",
310 sle64_to_cpu(ia
->index_block_vcn
),
311 (unsigned long long)vcn
, idx_ni
->mft_no
);
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
,
321 le32_to_cpu(ia
->index
.allocated_size
) + 0x18,
322 idx_ni
->itype
.index
.block_size
);
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
,
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
);
341 /* The first index entry. */
342 ie
= (INDEX_ENTRY
*)((u8
*)&ia
->index
+
343 le32_to_cpu(ia
->index
.entries_offset
));
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.
349 for (;; ie
= (INDEX_ENTRY
*)((u8
*)ie
+ le16_to_cpu(ie
->length
))) {
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
);
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.
362 if (ie
->flags
& INDEX_ENTRY_END
)
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
);
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
)) {
379 ictx
->is_in_root
= false;
381 ictx
->base_ni
= NULL
;
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.
390 rc
= ntfs_collate(vol
, idx_ni
->itype
.index
.collation_rule
, key
,
391 key_len
, &ie
->key
, le16_to_cpu(ie
->key_length
));
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.
400 * A match should never happen as the memcmp() call should have
401 * cought it, but we still treat it correctly.
405 /* The keys are not equal, continue the search. */
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.
411 if (!(ie
->flags
& INDEX_ENTRY_NODE
)) {
412 ntfs_debug("Entry not found.");
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
);
421 /* Child node present, descend into it. */
423 vcn
= sle64_to_cpup((sle64
*)((u8
*)ie
+ le16_to_cpu(ie
->length
) - 8));
426 * If vcn is in the same page cache page as old_vcn we recycle
429 if (old_vcn
<< vol
->cluster_size_bits
>>
430 PAGE_CACHE_SHIFT
== vcn
<<
431 vol
->cluster_size_bits
>>
433 goto fast_descend_into_child_node
;
435 ntfs_unmap_page(page
);
436 goto descend_into_child_node
;
438 ntfs_error(sb
, "Negative child node vcn in inode 0x%lx.",
442 ntfs_unmap_page(page
);
447 ntfs_attr_put_search_ctx(actx
);
449 unmap_mft_record(base_ni
);
452 ntfs_error(sb
, "Corrupt index. Aborting lookup.");