fs/ntfs/index.c

   1 /*
   2  * index.c - NTFS kernel index handling.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2004 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 "ntfs.h"
  23 #include "collate.h"
  24 #include "index.h"
  25
  26 /**
  27  * ntfs_index_ctx_get - allocate and initialize a new index context
  28  * @idx_ni:     ntfs index inode with which to initialize the context
  29  *
  30  * Allocate a new index context, initialize it with @idx_ni and return it.
  31  * Return NULL if allocation failed.
  32  *
  33  * Locking:  Caller must hold i_sem on the index inode.
  34  */
  35 ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
  36 {
  37         ntfs_index_context *ictx;
  38
  39         ictx = kmem_cache_alloc(ntfs_index_ctx_cache, SLAB_NOFS);
  40         if (ictx) {
  41                 ictx->idx_ni = idx_ni;
  42                 ictx->entry = NULL;
  43                 ictx->data = NULL;
  44                 ictx->data_len = 0;
  45                 ictx->is_in_root = 0;
  46                 ictx->ir = NULL;
  47                 ictx->actx = NULL;
  48                 ictx->base_ni = NULL;
  49                 ictx->ia = NULL;
  50                 ictx->page = NULL;
  51         }
  52         return ictx;
  53 }
  54
  55 /**
  56  * ntfs_index_ctx_put - release an index context
  57  * @ictx:       index context to free
  58  *
  59  * Release the index context @ictx, releasing all associated resources.
  60  *
  61  * Locking:  Caller must hold i_sem on the index inode.
  62  */
  63 void ntfs_index_ctx_put(ntfs_index_context *ictx)
  64 {
  65         if (ictx->entry) {
  66                 if (ictx->is_in_root) {
  67                         if (ictx->actx)
  68                                 ntfs_attr_put_search_ctx(ictx->actx);
  69                         if (ictx->base_ni)
  70                                 unmap_mft_record(ictx->base_ni);
  71                 } else {
  72                         struct page *page = ictx->page;
  73                         if (page) {
  74                                 BUG_ON(!PageLocked(page));
  75                                 unlock_page(page);
  76                                 ntfs_unmap_page(page);
  77                         }
  78                 }
  79         }
  80         kmem_cache_free(ntfs_index_ctx_cache, ictx);
  81         return;
  82 }
  83
  84 /**
  85  * ntfs_index_lookup - find a key in an index and return its index entry
  86  * @key:        [IN] key for which to search in the index
  87  * @key_len:    [IN] length of @key in bytes
  88  * @ictx:       [IN/OUT] context describing the index and the returned entry
  89  *
  90  * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
  91  * call to ntfs_index_ctx_get().
  92  *
  93  * Look for the @key in the index specified by the index lookup context @ictx.
  94  * ntfs_index_lookup() walks the contents of the index looking for the @key.
  95  *
  96  * If the @key is found in the index, 0 is returned and @ictx is setup to
  97  * describe the index entry containing the matching @key.  @ictx->entry is the
  98  * index entry and @ictx->data and @ictx->data_len are the index entry data and
  99  * its length in bytes, respectively.
 100  *
 101  * If the @key is not found in the index, -ENOENT is returned and @ictx is
 102  * setup to describe the index entry whose key collates immediately after the
 103  * search @key, i.e. this is the position in the index at which an index entry
 104  * with a key of @key would need to be inserted.
 105  *
 106  * If an error occurs return the negative error code and @ictx is left
 107  * untouched.
 108  *
 109  * When finished with the entry and its data, call ntfs_index_ctx_put() to free
 110  * the context and other associated resources.
 111  *
 112  * If the index entry was modified, call flush_dcache_index_entry_page()
 113  * immediately after the modification and either ntfs_index_entry_mark_dirty()
 114  * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
 115  * ensure that the changes are written to disk.
 116  *
 117  * Locking:  - Caller must hold i_sem on the index inode.
 118  *           - Each page cache page in the index allocation mapping must be
 119  *             locked whilst being accessed otherwise we may find a corrupt
 120  *             page due to it being under ->writepage at the moment which
 121  *             applies the mst protection fixups before writing out and then
 122  *             removes them again after the write is complete after which it
 123  *             unlocks the page.
 124  */
 125 int ntfs_index_lookup(const void *key, const int key_len,
 126                 ntfs_index_context *ictx)
 127 {
 128         VCN vcn, old_vcn;
 129         ntfs_inode *idx_ni = ictx->idx_ni;
 130         ntfs_volume *vol = idx_ni->vol;
 131         struct super_block *sb = vol->sb;
 132         ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
 133         MFT_RECORD *m;
 134         INDEX_ROOT *ir;
 135         INDEX_ENTRY *ie;
 136         INDEX_ALLOCATION *ia;
 137         u8 *index_end, *kaddr;
 138         ntfs_attr_search_ctx *actx;
 139         struct address_space *ia_mapping;
 140         struct page *page;
 141         int rc, err = 0;
 142
 143         ntfs_debug("Entering.");
 144         BUG_ON(!NInoAttr(idx_ni));
 145         BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
 146         BUG_ON(idx_ni->nr_extents != -1);
 147         BUG_ON(!base_ni);
 148         BUG_ON(!key);
 149         BUG_ON(key_len <= 0);
 150         if (!ntfs_is_collation_rule_supported(
 151                         idx_ni->itype.index.collation_rule)) {
 152                 ntfs_error(sb, "Index uses unsupported collation rule 0x%x.  "
 153                                 "Aborting lookup.", le32_to_cpu(
 154                                 idx_ni->itype.index.collation_rule));
 155                 return -EOPNOTSUPP;
 156         }
 157         /* Get hold of the mft record for the index inode. */
 158         m = map_mft_record(base_ni);
 159         if (IS_ERR(m)) {
 160                 ntfs_error(sb, "map_mft_record() failed with error code %ld.",
 161                                 -PTR_ERR(m));
 162                 return PTR_ERR(m);
 163         }
 164         actx = ntfs_attr_get_search_ctx(base_ni, m);
 165         if (unlikely(!actx)) {
 166                 err = -ENOMEM;
 167                 goto err_out;
 168         }
 169         /* Find the index root attribute in the mft record. */
 170         err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
 171                         CASE_SENSITIVE, 0, NULL, 0, actx);
 172         if (unlikely(err)) {
 173                 if (err == -ENOENT) {
 174                         ntfs_error(sb, "Index root attribute missing in inode "
 175                                         "0x%lx.", idx_ni->mft_no);
 176                         err = -EIO;
 177                 }
 178                 goto err_out;
 179         }
 180         /* Get to the index root value (it has been verified in read_inode). */
 181         ir = (INDEX_ROOT*)((u8*)actx->attr +
 182                         le16_to_cpu(actx->attr->data.resident.value_offset));
 183         index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
 184         /* The first index entry. */
 185         ie = (INDEX_ENTRY*)((u8*)&ir->index +
 186                         le32_to_cpu(ir->index.entries_offset));
 187         /*
 188          * Loop until we exceed valid memory (corruption case) or until we
 189          * reach the last entry.
 190          */
 191         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 192                 /* Bounds checks. */
 193                 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
 194                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 195                                 (u8*)ie + le16_to_cpu(ie->length) > index_end)
 196                         goto idx_err_out;
 197                 /*
 198                  * The last entry cannot contain a key.  It can however contain
 199                  * a pointer to a child node in the B+tree so we just break out.
 200                  */
 201                 if (ie->flags & INDEX_ENTRY_END)
 202                         break;
 203                 /* Further bounds checks. */
 204                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 205                                 le16_to_cpu(ie->key_length) >
 206                                 le16_to_cpu(ie->data.vi.data_offset) ||
 207                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 208                                 le16_to_cpu(ie->data.vi.data_length) >
 209                                 le16_to_cpu(ie->length))
 210                         goto idx_err_out;
 211                 /* If the keys match perfectly, we setup @ictx and return 0. */
 212                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 213                                 &ie->key, key_len)) {
 214 ir_done:
 215                         ictx->is_in_root = TRUE;
 216                         ictx->actx = actx;
 217                         ictx->base_ni = base_ni;
 218                         ictx->ia = NULL;
 219                         ictx->page = NULL;
 220 done:
 221                         ictx->entry = ie;
 222                         ictx->data = (u8*)ie +
 223                                         le16_to_cpu(ie->data.vi.data_offset);
 224                         ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
 225                         ntfs_debug("Done.");
 226                         return err;
 227                 }
 228                 /*
 229                  * Not a perfect match, need to do full blown collation so we
 230                  * know which way in the B+tree we have to go.
 231                  */
 232                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 233                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 234                 /*
 235                  * If @key collates before the key of the current entry, there
 236                  * is definitely no such key in this index but we might need to
 237                  * descend into the B+tree so we just break out of the loop.
 238                  */
 239                 if (rc == -1)
 240                         break;
 241                 /*
 242                  * A match should never happen as the memcmp() call should have
 243                  * cought it, but we still treat it correctly.
 244                  */
 245                 if (!rc)
 246                         goto ir_done;
 247                 /* The keys are not equal, continue the search. */
 248         }
 249         /*
 250          * We have finished with this index without success.  Check for the
 251          * presence of a child node and if not present setup @ictx and return
 252          * -ENOENT.
 253          */
 254         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 255                 ntfs_debug("Entry not found.");
 256                 err = -ENOENT;
 257                 goto ir_done;
 258         } /* Child node present, descend into it. */
 259         /* Consistency check: Verify that an index allocation exists. */
 260         if (!NInoIndexAllocPresent(idx_ni)) {
 261                 ntfs_error(sb, "No index allocation attribute but index entry "
 262                                 "requires one.  Inode 0x%lx is corrupt or "
 263                                 "driver bug.", idx_ni->mft_no);
 264                 err = -EIO;
 265                 goto err_out;
 266         }
 267         /* Get the starting vcn of the index_block holding the child node. */
 268         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 269         ia_mapping = VFS_I(idx_ni)->i_mapping;
 270         /*
 271          * We are done with the index root and the mft record.  Release them,
 272          * otherwise we deadlock with ntfs_map_page().
 273          */
 274         ntfs_attr_put_search_ctx(actx);
 275         unmap_mft_record(base_ni);
 276         m = NULL;
 277         actx = NULL;
 278 descend_into_child_node:
 279         /*
 280          * Convert vcn to index into the index allocation attribute in units
 281          * of PAGE_CACHE_SIZE and map the page cache page, reading it from
 282          * disk if necessary.
 283          */
 284         page = ntfs_map_page(ia_mapping, vcn <<
 285                         idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
 286         if (IS_ERR(page)) {
 287                 ntfs_error(sb, "Failed to map index page, error %ld.",
 288                                 -PTR_ERR(page));
 289                 err = PTR_ERR(page);
 290                 goto err_out;
 291         }
 292         lock_page(page);
 293         kaddr = (u8*)page_address(page);
 294 fast_descend_into_child_node:
 295         /* Get to the index allocation block. */
 296         ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
 297                         idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
 298         /* Bounds checks. */
 299         if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
 300                 ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
 301                                 "0x%lx or driver bug.", idx_ni->mft_no);
 302                 err = -EIO;
 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                 err = -EIO;
 313                 goto unm_err_out;
 314         }
 315         if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
 316                         idx_ni->itype.index.block_size) {
 317                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
 318                                 "a size (%u) differing from the index "
 319                                 "specified size (%u).  Inode is corrupt or "
 320                                 "driver bug.", (unsigned long long)vcn,
 321                                 idx_ni->mft_no,
 322                                 le32_to_cpu(ia->index.allocated_size) + 0x18,
 323                                 idx_ni->itype.index.block_size);
 324                 err = -EIO;
 325                 goto unm_err_out;
 326         }
 327         index_end = (u8*)ia + idx_ni->itype.index.block_size;
 328         if (index_end > kaddr + PAGE_CACHE_SIZE) {
 329                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
 330                                 "crosses page boundary.  Impossible!  Cannot "
 331                                 "access!  This is probably a bug in the "
 332                                 "driver.", (unsigned long long)vcn,
 333                                 idx_ni->mft_no);
 334                 err = -EIO;
 335                 goto unm_err_out;
 336         }
 337         index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
 338         if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
 339                 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
 340                                 "0x%lx exceeds maximum size.",
 341                                 (unsigned long long)vcn, idx_ni->mft_no);
 342                 err = -EIO;
 343                 goto unm_err_out;
 344         }
 345         /* The first index entry. */
 346         ie = (INDEX_ENTRY*)((u8*)&ia->index +
 347                         le32_to_cpu(ia->index.entries_offset));
 348         /*
 349          * Iterate similar to above big loop but applied to index buffer, thus
 350          * loop until we exceed valid memory (corruption case) or until we
 351          * reach the last entry.
 352          */
 353         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 354                 /* Bounds checks. */
 355                 if ((u8*)ie < (u8*)ia || (u8*)ie +
 356                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 357                                 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
 358                         ntfs_error(sb, "Index entry out of bounds in inode "
 359                                         "0x%lx.", idx_ni->mft_no);
 360                         err = -EIO;
 361                         goto unm_err_out;
 362                 }
 363                 /*
 364                  * The last entry cannot contain a ket.  It can however contain
 365                  * a pointer to a child node in the B+tree so we just break out.
 366                  */
 367                 if (ie->flags & INDEX_ENTRY_END)
 368                         break;
 369                 /* Further bounds checks. */
 370                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 371                                 le16_to_cpu(ie->key_length) >
 372                                 le16_to_cpu(ie->data.vi.data_offset) ||
 373                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 374                                 le16_to_cpu(ie->data.vi.data_length) >
 375                                 le16_to_cpu(ie->length)) {
 376                         ntfs_error(sb, "Index entry out of bounds in inode "
 377                                         "0x%lx.", idx_ni->mft_no);
 378                         err = -EIO;
 379                         goto unm_err_out;
 380                 }
 381                 /* If the keys match perfectly, we setup @ictx and return 0. */
 382                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 383                                 &ie->key, key_len)) {
 384 ia_done:
 385                         ictx->is_in_root = FALSE;
 386                         ictx->actx = NULL;
 387                         ictx->base_ni = NULL;
 388                         ictx->ia = ia;
 389                         ictx->page = page;
 390                         goto done;
 391                 }
 392                 /*
 393                  * Not a perfect match, need to do full blown collation so we
 394                  * know which way in the B+tree we have to go.
 395                  */
 396                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 397                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 398                 /*
 399                  * If @key collates before the key of the current entry, there
 400                  * is definitely no such key in this index but we might need to
 401                  * descend into the B+tree so we just break out of the loop.
 402                  */
 403                 if (rc == -1)
 404                         break;
 405                 /*
 406                  * A match should never happen as the memcmp() call should have
 407                  * cought it, but we still treat it correctly.
 408                  */
 409                 if (!rc)
 410                         goto ia_done;
 411                 /* The keys are not equal, continue the search. */
 412         }
 413         /*
 414          * We have finished with this index buffer without success.  Check for
 415          * the presence of a child node and if not present return -ENOENT.
 416          */
 417         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 418                 ntfs_debug("Entry not found.");
 419                 err = -ENOENT;
 420                 goto ia_done;
 421         }
 422         if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
 423                 ntfs_error(sb, "Index entry with child node found in a leaf "
 424                                 "node in inode 0x%lx.", idx_ni->mft_no);
 425                 err = -EIO;
 426                 goto unm_err_out;
 427         }
 428         /* Child node present, descend into it. */
 429         old_vcn = vcn;
 430         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 431         if (vcn >= 0) {
 432                 /*
 433                  * If vcn is in the same page cache page as old_vcn we recycle
 434                  * the mapped page.
 435                  */
 436                 if (old_vcn << vol->cluster_size_bits >>
 437                                 PAGE_CACHE_SHIFT == vcn <<
 438                                 vol->cluster_size_bits >>
 439                                 PAGE_CACHE_SHIFT)
 440                         goto fast_descend_into_child_node;
 441                 unlock_page(page);
 442                 ntfs_unmap_page(page);
 443                 goto descend_into_child_node;
 444         }
 445         ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
 446                         idx_ni->mft_no);
 447         err = -EIO;
 448 unm_err_out:
 449         unlock_page(page);
 450         ntfs_unmap_page(page);
 451 err_out:
 452         if (actx)
 453                 ntfs_attr_put_search_ctx(actx);
 454         if (m)
 455                 unmap_mft_record(base_ni);
 456         return err;
 457 idx_err_out:
 458         ntfs_error(sb, "Corrupt index.  Aborting lookup.");
 459         err = -EIO;
 460         goto err_out;
 461 }
 462
 463 #ifdef NTFS_RW
 464
 465 /**
 466  * __ntfs_index_entry_mark_dirty - mark an index allocation entry dirty
 467  * @ictx:       ntfs index context describing the index entry
 468  *
 469  * NOTE: You want to use fs/ntfs/index.h::ntfs_index_entry_mark_dirty() instead!
 470  *
 471  * Mark the index allocation entry described by the index entry context @ictx
 472  * dirty.
 473  *
 474  * The index entry must be in an index block belonging to the index allocation
 475  * attribute.  Mark the buffers belonging to the index record as well as the
 476  * page cache page the index block is in dirty.  This automatically marks the
 477  * VFS inode of the ntfs index inode to which the index entry belongs dirty,
 478  * too (I_DIRTY_PAGES) and this in turn ensures the page buffers, and hence the
 479  * dirty index block, will be written out to disk later.
 480  */
 481 void __ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
 482 {
 483         ntfs_inode *ni;
 484         struct page *page;
 485         struct buffer_head *bh, *head;
 486         unsigned int rec_start, rec_end, bh_size, bh_start, bh_end;
 487
 488         BUG_ON(ictx->is_in_root);
 489         ni = ictx->idx_ni;
 490         page = ictx->page;
 491         BUG_ON(!page_has_buffers(page));
 492         /*
 493          * If the index block is the same size as the page cache page, set all
 494          * the buffers in the page, as well as the page itself, dirty.
 495          */
 496         if (ni->itype.index.block_size == PAGE_CACHE_SIZE) {
 497                 __set_page_dirty_buffers(page);
 498                 return;
 499         }
 500         /* Set only the buffers in which the index block is located dirty. */
 501         rec_start = (unsigned int)((u8*)ictx->ia - (u8*)page_address(page));
 502         rec_end = rec_start + ni->itype.index.block_size;
 503         bh_size = ni->vol->sb->s_blocksize;
 504         bh_start = 0;
 505         bh = head = page_buffers(page);
 506         do {
 507                 bh_end = bh_start + bh_size;
 508                 if ((bh_start >= rec_start) && (bh_end <= rec_end))
 509                         set_buffer_dirty(bh);
 510                 bh_start = bh_end;
 511         } while ((bh = bh->b_this_page) != head);
 512         /* Finally, set the page itself dirty, too. */
 513         __set_page_dirty_nobuffers(page);
 514 }
 515
 516 #endif /* NTFS_RW */