diff options
Diffstat (limited to 'fs/ntfs/index.c')
| -rw-r--r-- | fs/ntfs/index.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/fs/ntfs/index.c b/fs/ntfs/index.c new file mode 100644 index 000000000..096c13569 --- /dev/null +++ b/fs/ntfs/index.c @@ -0,0 +1,454 @@ +/* + * index.c - NTFS kernel index handling. Part of the Linux-NTFS project. + * + * Copyright (c) 2004-2005 Anton Altaparmakov + * + * This program/include file is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as published + * by the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program/include file is distributed in the hope that it will be + * useful, but WITHOUT ANY WARRANTY; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program (in the main directory of the Linux-NTFS + * distribution in the file COPYING); if not, write to the Free Software + * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/slab.h> + +#include "aops.h" +#include "collate.h" +#include "debug.h" +#include "index.h" +#include "ntfs.h" + +/** + * ntfs_index_ctx_get - allocate and initialize a new index context + * @idx_ni: ntfs index inode with which to initialize the context + * + * Allocate a new index context, initialize it with @idx_ni and return it. + * Return NULL if allocation failed. + * + * Locking: Caller must hold i_mutex on the index inode. + */ +ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni) +{ + ntfs_index_context *ictx; + + ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS); + if (ictx) + *ictx = (ntfs_index_context){ .idx_ni = idx_ni }; + return ictx; +} + +/** + * ntfs_index_ctx_put - release an index context + * @ictx: index context to free + * + * Release the index context @ictx, releasing all associated resources. + * + * Locking: Caller must hold i_mutex on the index inode. + */ +void ntfs_index_ctx_put(ntfs_index_context *ictx) +{ + if (ictx->entry) { + if (ictx->is_in_root) { + if (ictx->actx) + ntfs_attr_put_search_ctx(ictx->actx); + if (ictx->base_ni) + unmap_mft_record(ictx->base_ni); + } else { + struct page *page = ictx->page; + if (page) { + BUG_ON(!PageLocked(page)); + unlock_page(page); + ntfs_unmap_page(page); + } + } + } + kmem_cache_free(ntfs_index_ctx_cache, ictx); + return; +} + +/** + * ntfs_index_lookup - find a key in an index and return its index entry + * @key: [IN] key for which to search in the index + * @key_len: [IN] length of @key in bytes + * @ictx: [IN/OUT] context describing the index and the returned entry + * + * Before calling ntfs_index_lookup(), @ictx must have been obtained from a + * call to ntfs_index_ctx_get(). + * + * Look for the @key in the index specified by the index lookup context @ictx. + * ntfs_index_lookup() walks the contents of the index looking for the @key. + * + * If the @key is found in the index, 0 is returned and @ictx is setup to + * describe the index entry containing the matching @key. @ictx->entry is the + * index entry and @ictx->data and @ictx->data_len are the index entry data and + * its length in bytes, respectively. + * + * If the @key is not found in the index, -ENOENT is returned and @ictx is + * setup to describe the index entry whose key collates immediately after the + * search @key, i.e. this is the position in the index at which an index entry + * with a key of @key would need to be inserted. + * + * If an error occurs return the negative error code and @ictx is left + * untouched. + * + * When finished with the entry and its data, call ntfs_index_ctx_put() to free + * the context and other associated resources. + * + * If the index entry was modified, call flush_dcache_index_entry_page() + * immediately after the modification and either ntfs_index_entry_mark_dirty() + * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to + * ensure that the changes are written to disk. + * + * Locking: - Caller must hold i_mutex on the index inode. + * - Each page cache page in the index allocation mapping must be + * locked whilst being accessed otherwise we may find a corrupt + * page due to it being under ->writepage at the moment which + * applies the mst protection fixups before writing out and then + * removes them again after the write is complete after which it + * unlocks the page. + */ +int ntfs_index_lookup(const void *key, const int key_len, + ntfs_index_context *ictx) +{ + VCN vcn, old_vcn; + ntfs_inode *idx_ni = ictx->idx_ni; + ntfs_volume *vol = idx_ni->vol; + struct super_block *sb = vol->sb; + ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino; + MFT_RECORD *m; + INDEX_ROOT *ir; + INDEX_ENTRY *ie; + INDEX_ALLOCATION *ia; + u8 *index_end, *kaddr; + ntfs_attr_search_ctx *actx; + struct address_space *ia_mapping; + struct page *page; + int rc, err = 0; + + ntfs_debug("Entering."); + BUG_ON(!NInoAttr(idx_ni)); + BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION); + BUG_ON(idx_ni->nr_extents != -1); + BUG_ON(!base_ni); + BUG_ON(!key); + BUG_ON(key_len <= 0); + if (!ntfs_is_collation_rule_supported( + idx_ni->itype.index.collation_rule)) { + ntfs_error(sb, "Index uses unsupported collation rule 0x%x. " + "Aborting lookup.", le32_to_cpu( + idx_ni->itype.index.collation_rule)); + return -EOPNOTSUPP; + } + /* Get hold of the mft record for the index inode. */ + m = map_mft_record(base_ni); + if (IS_ERR(m)) { + ntfs_error(sb, "map_mft_record() failed with error code %ld.", + -PTR_ERR(m)); + return PTR_ERR(m); + } + actx = ntfs_attr_get_search_ctx(base_ni, m); + if (unlikely(!actx)) { + err = -ENOMEM; + goto err_out; + } + /* Find the index root attribute in the mft record. */ + err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len, + CASE_SENSITIVE, 0, NULL, 0, actx); + if (unlikely(err)) { + if (err == -ENOENT) { + ntfs_error(sb, "Index root attribute missing in inode " + "0x%lx.", idx_ni->mft_no); + err = -EIO; + } + goto err_out; + } + /* Get to the index root value (it has been verified in read_inode). */ + ir = (INDEX_ROOT*)((u8*)actx->attr + + le16_to_cpu(actx->attr->data.resident.value_offset)); + index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length); + /* The first index entry. */ + ie = (INDEX_ENTRY*)((u8*)&ir->index + + le32_to_cpu(ir->index.entries_offset)); + /* + * Loop until we exceed valid memory (corruption case) or until we + * reach the last entry. + */ + for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { + /* Bounds checks. */ + if ((u8*)ie < (u8*)actx->mrec || (u8*)ie + + sizeof(INDEX_ENTRY_HEADER) > index_end || + (u8*)ie + le16_to_cpu(ie->length) > index_end) + goto idx_err_out; + /* + * The last entry cannot contain a key. It can however contain + * a pointer to a child node in the B+tree so we just break out. + */ + if (ie->flags & INDEX_ENTRY_END) + break; + /* Further bounds checks. */ + if ((u32)sizeof(INDEX_ENTRY_HEADER) + + le16_to_cpu(ie->key_length) > + le16_to_cpu(ie->data.vi.data_offset) || + (u32)le16_to_cpu(ie->data.vi.data_offset) + + le16_to_cpu(ie->data.vi.data_length) > + le16_to_cpu(ie->length)) + goto idx_err_out; + /* If the keys match perfectly, we setup @ictx and return 0. */ + if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, + &ie->key, key_len)) { +ir_done: + ictx->is_in_root = true; + ictx->ir = ir; + ictx->actx = actx; + ictx->base_ni = base_ni; + ictx->ia = NULL; + ictx->page = NULL; +done: + ictx->entry = ie; + ictx->data = (u8*)ie + + le16_to_cpu(ie->data.vi.data_offset); + ictx->data_len = le16_to_cpu(ie->data.vi.data_length); + ntfs_debug("Done."); + return err; + } + /* + * Not a perfect match, need to do full blown collation so we + * know which way in the B+tree we have to go. + */ + rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, + key_len, &ie->key, le16_to_cpu(ie->key_length)); + /* + * If @key collates before the key of the current entry, there + * is definitely no such key in this index but we might need to + * descend into the B+tree so we just break out of the loop. + */ + if (rc == -1) + break; + /* + * A match should never happen as the memcmp() call should have + * cought it, but we still treat it correctly. + */ + if (!rc) + goto ir_done; + /* The keys are not equal, continue the search. */ + } + /* + * We have finished with this index without success. Check for the + * presence of a child node and if not present setup @ictx and return + * -ENOENT. + */ + if (!(ie->flags & INDEX_ENTRY_NODE)) { + ntfs_debug("Entry not found."); + err = -ENOENT; + goto ir_done; + } /* Child node present, descend into it. */ + /* Consistency check: Verify that an index allocation exists. */ + if (!NInoIndexAllocPresent(idx_ni)) { + ntfs_error(sb, "No index allocation attribute but index entry " + "requires one. Inode 0x%lx is corrupt or " + "driver bug.", idx_ni->mft_no); + goto err_out; + } + /* Get the starting vcn of the index_block holding the child node. */ + vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); + ia_mapping = VFS_I(idx_ni)->i_mapping; + /* + * We are done with the index root and the mft record. Release them, + * otherwise we deadlock with ntfs_map_page(). + */ + ntfs_attr_put_search_ctx(actx); + unmap_mft_record(base_ni); + m = NULL; + actx = NULL; +descend_into_child_node: + /* + * Convert vcn to index into the index allocation attribute in units + * of PAGE_CACHE_SIZE and map the page cache page, reading it from + * disk if necessary. + */ + page = ntfs_map_page(ia_mapping, vcn << + idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT); + if (IS_ERR(page)) { + ntfs_error(sb, "Failed to map index page, error %ld.", + -PTR_ERR(page)); + err = PTR_ERR(page); + goto err_out; + } + lock_page(page); + kaddr = (u8*)page_address(page); +fast_descend_into_child_node: + /* Get to the index allocation block. */ + ia = (INDEX_ALLOCATION*)(kaddr + ((vcn << + idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK)); + /* Bounds checks. */ + if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) { + ntfs_error(sb, "Out of bounds check failed. Corrupt inode " + "0x%lx or driver bug.", idx_ni->mft_no); + goto unm_err_out; + } + /* Catch multi sector transfer fixup errors. */ + if (unlikely(!ntfs_is_indx_record(ia->magic))) { + ntfs_error(sb, "Index record with vcn 0x%llx is corrupt. " + "Corrupt inode 0x%lx. Run chkdsk.", + (long long)vcn, idx_ni->mft_no); + goto unm_err_out; + } + if (sle64_to_cpu(ia->index_block_vcn) != vcn) { + ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is " + "different from expected VCN (0x%llx). Inode " + "0x%lx is corrupt or driver bug.", + (unsigned long long) + sle64_to_cpu(ia->index_block_vcn), + (unsigned long long)vcn, idx_ni->mft_no); + goto unm_err_out; + } + if (le32_to_cpu(ia->index.allocated_size) + 0x18 != + idx_ni->itype.index.block_size) { + ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has " + "a size (%u) differing from the index " + "specified size (%u). Inode is corrupt or " + "driver bug.", (unsigned long long)vcn, + idx_ni->mft_no, + le32_to_cpu(ia->index.allocated_size) + 0x18, + idx_ni->itype.index.block_size); + goto unm_err_out; + } + index_end = (u8*)ia + idx_ni->itype.index.block_size; + if (index_end > kaddr + PAGE_CACHE_SIZE) { + ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx " + "crosses page boundary. Impossible! Cannot " + "access! This is probably a bug in the " + "driver.", (unsigned long long)vcn, + idx_ni->mft_no); + goto unm_err_out; + } + index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length); + if (index_end > (u8*)ia + idx_ni->itype.index.block_size) { + ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode " + "0x%lx exceeds maximum size.", + (unsigned long long)vcn, idx_ni->mft_no); + goto unm_err_out; + } + /* The first index entry. */ + ie = (INDEX_ENTRY*)((u8*)&ia->index + + le32_to_cpu(ia->index.entries_offset)); + /* + * Iterate similar to above big loop but applied to index buffer, thus + * loop until we exceed valid memory (corruption case) or until we + * reach the last entry. + */ + for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { + /* Bounds checks. */ + if ((u8*)ie < (u8*)ia || (u8*)ie + + sizeof(INDEX_ENTRY_HEADER) > index_end || + (u8*)ie + le16_to_cpu(ie->length) > index_end) { + ntfs_error(sb, "Index entry out of bounds in inode " + "0x%lx.", idx_ni->mft_no); + goto unm_err_out; + } + /* + * The last entry cannot contain a key. It can however contain + * a pointer to a child node in the B+tree so we just break out. + */ + if (ie->flags & INDEX_ENTRY_END) + break; + /* Further bounds checks. */ + if ((u32)sizeof(INDEX_ENTRY_HEADER) + + le16_to_cpu(ie->key_length) > + le16_to_cpu(ie->data.vi.data_offset) || + (u32)le16_to_cpu(ie->data.vi.data_offset) + + le16_to_cpu(ie->data.vi.data_length) > + le16_to_cpu(ie->length)) { + ntfs_error(sb, "Index entry out of bounds in inode " + "0x%lx.", idx_ni->mft_no); + goto unm_err_out; + } + /* If the keys match perfectly, we setup @ictx and return 0. */ + if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, + &ie->key, key_len)) { +ia_done: + ictx->is_in_root = false; + ictx->actx = NULL; + ictx->base_ni = NULL; + ictx->ia = ia; + ictx->page = page; + goto done; + } + /* + * Not a perfect match, need to do full blown collation so we + * know which way in the B+tree we have to go. + */ + rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, + key_len, &ie->key, le16_to_cpu(ie->key_length)); + /* + * If @key collates before the key of the current entry, there + * is definitely no such key in this index but we might need to + * descend into the B+tree so we just break out of the loop. + */ + if (rc == -1) + break; + /* + * A match should never happen as the memcmp() call should have + * cought it, but we still treat it correctly. + */ + if (!rc) + goto ia_done; + /* The keys are not equal, continue the search. */ + } + /* + * We have finished with this index buffer without success. Check for + * the presence of a child node and if not present return -ENOENT. + */ + if (!(ie->flags & INDEX_ENTRY_NODE)) { + ntfs_debug("Entry not found."); + err = -ENOENT; + goto ia_done; + } + if ((ia->index.flags & NODE_MASK) == LEAF_NODE) { + ntfs_error(sb, "Index entry with child node found in a leaf " + "node in inode 0x%lx.", idx_ni->mft_no); + goto unm_err_out; + } + /* Child node present, descend into it. */ + old_vcn = vcn; + vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); + if (vcn >= 0) { + /* + * If vcn is in the same page cache page as old_vcn we recycle + * the mapped page. + */ + if (old_vcn << vol->cluster_size_bits >> + PAGE_CACHE_SHIFT == vcn << + vol->cluster_size_bits >> + PAGE_CACHE_SHIFT) + goto fast_descend_into_child_node; + unlock_page(page); + ntfs_unmap_page(page); + goto descend_into_child_node; + } + ntfs_error(sb, "Negative child node vcn in inode 0x%lx.", + idx_ni->mft_no); +unm_err_out: + unlock_page(page); + ntfs_unmap_page(page); +err_out: + if (!err) + err = -EIO; + if (actx) + ntfs_attr_put_search_ctx(actx); + if (m) + unmap_mft_record(base_ni); + return err; +idx_err_out: + ntfs_error(sb, "Corrupt index. Aborting lookup."); + goto err_out; +} |