441 lines
14 KiB
C
441 lines
14 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* index.c - NTFS kernel index handling. Part of the Linux-NTFS project.
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*
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* Copyright (c) 2004-2005 Anton Altaparmakov
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*/
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#include <linux/slab.h>
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#include "aops.h"
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#include "collate.h"
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#include "debug.h"
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#include "index.h"
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#include "ntfs.h"
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/**
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* ntfs_index_ctx_get - allocate and initialize a new index context
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* @idx_ni: ntfs index inode with which to initialize the context
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*
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* Allocate a new index context, initialize it with @idx_ni and return it.
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* Return NULL if allocation failed.
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*
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* Locking: Caller must hold i_mutex on the index inode.
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*/
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ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
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{
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ntfs_index_context *ictx;
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ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS);
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if (ictx)
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*ictx = (ntfs_index_context){ .idx_ni = idx_ni };
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return ictx;
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}
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/**
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* ntfs_index_ctx_put - release an index context
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* @ictx: index context to free
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*
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* Release the index context @ictx, releasing all associated resources.
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*
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* Locking: Caller must hold i_mutex on the index inode.
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*/
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void ntfs_index_ctx_put(ntfs_index_context *ictx)
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{
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if (ictx->entry) {
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if (ictx->is_in_root) {
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if (ictx->actx)
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ntfs_attr_put_search_ctx(ictx->actx);
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if (ictx->base_ni)
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unmap_mft_record(ictx->base_ni);
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} else {
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struct page *page = ictx->page;
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if (page) {
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BUG_ON(!PageLocked(page));
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unlock_page(page);
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ntfs_unmap_page(page);
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}
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}
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}
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kmem_cache_free(ntfs_index_ctx_cache, ictx);
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return;
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}
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/**
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* ntfs_index_lookup - find a key in an index and return its index entry
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* @key: [IN] key for which to search in the index
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* @key_len: [IN] length of @key in bytes
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* @ictx: [IN/OUT] context describing the index and the returned entry
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*
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* Before calling ntfs_index_lookup(), @ictx must have been obtained from a
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* call to ntfs_index_ctx_get().
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*
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* Look for the @key in the index specified by the index lookup context @ictx.
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* ntfs_index_lookup() walks the contents of the index looking for the @key.
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*
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* If the @key is found in the index, 0 is returned and @ictx is setup to
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* describe the index entry containing the matching @key. @ictx->entry is the
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* index entry and @ictx->data and @ictx->data_len are the index entry data and
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* its length in bytes, respectively.
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*
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* If the @key is not found in the index, -ENOENT is returned and @ictx is
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* setup to describe the index entry whose key collates immediately after the
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* search @key, i.e. this is the position in the index at which an index entry
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* with a key of @key would need to be inserted.
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*
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* If an error occurs return the negative error code and @ictx is left
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* untouched.
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*
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* When finished with the entry and its data, call ntfs_index_ctx_put() to free
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* the context and other associated resources.
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*
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* If the index entry was modified, call flush_dcache_index_entry_page()
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* immediately after the modification and either ntfs_index_entry_mark_dirty()
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* or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
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* ensure that the changes are written to disk.
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*
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* Locking: - Caller must hold i_mutex on the index inode.
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* - Each page cache page in the index allocation mapping must be
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* locked whilst being accessed otherwise we may find a corrupt
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* page due to it being under ->writepage at the moment which
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* applies the mst protection fixups before writing out and then
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* removes them again after the write is complete after which it
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* unlocks the page.
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*/
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int ntfs_index_lookup(const void *key, const int key_len,
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ntfs_index_context *ictx)
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{
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VCN vcn, old_vcn;
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ntfs_inode *idx_ni = ictx->idx_ni;
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ntfs_volume *vol = idx_ni->vol;
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struct super_block *sb = vol->sb;
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ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
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MFT_RECORD *m;
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INDEX_ROOT *ir;
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INDEX_ENTRY *ie;
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INDEX_ALLOCATION *ia;
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u8 *index_end, *kaddr;
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ntfs_attr_search_ctx *actx;
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struct address_space *ia_mapping;
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struct page *page;
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int rc, err = 0;
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ntfs_debug("Entering.");
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BUG_ON(!NInoAttr(idx_ni));
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BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
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BUG_ON(idx_ni->nr_extents != -1);
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BUG_ON(!base_ni);
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BUG_ON(!key);
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BUG_ON(key_len <= 0);
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if (!ntfs_is_collation_rule_supported(
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idx_ni->itype.index.collation_rule)) {
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ntfs_error(sb, "Index uses unsupported collation rule 0x%x. "
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"Aborting lookup.", le32_to_cpu(
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idx_ni->itype.index.collation_rule));
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return -EOPNOTSUPP;
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}
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/* Get hold of the mft record for the index inode. */
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m = map_mft_record(base_ni);
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if (IS_ERR(m)) {
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ntfs_error(sb, "map_mft_record() failed with error code %ld.",
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-PTR_ERR(m));
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return PTR_ERR(m);
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}
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actx = ntfs_attr_get_search_ctx(base_ni, m);
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if (unlikely(!actx)) {
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err = -ENOMEM;
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goto err_out;
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}
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/* Find the index root attribute in the mft record. */
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err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
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CASE_SENSITIVE, 0, NULL, 0, actx);
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if (unlikely(err)) {
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if (err == -ENOENT) {
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ntfs_error(sb, "Index root attribute missing in inode "
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"0x%lx.", idx_ni->mft_no);
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err = -EIO;
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}
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goto err_out;
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}
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/* Get to the index root value (it has been verified in read_inode). */
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ir = (INDEX_ROOT*)((u8*)actx->attr +
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le16_to_cpu(actx->attr->data.resident.value_offset));
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index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
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/* The first index entry. */
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ie = (INDEX_ENTRY*)((u8*)&ir->index +
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le32_to_cpu(ir->index.entries_offset));
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/*
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* Loop until we exceed valid memory (corruption case) or until we
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* reach the last entry.
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*/
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for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
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/* Bounds checks. */
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if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
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sizeof(INDEX_ENTRY_HEADER) > index_end ||
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(u8*)ie + le16_to_cpu(ie->length) > index_end)
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goto idx_err_out;
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/*
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* The last entry cannot contain a key. It can however contain
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* a pointer to a child node in the B+tree so we just break out.
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*/
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if (ie->flags & INDEX_ENTRY_END)
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break;
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/* Further bounds checks. */
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if ((u32)sizeof(INDEX_ENTRY_HEADER) +
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le16_to_cpu(ie->key_length) >
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le16_to_cpu(ie->data.vi.data_offset) ||
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(u32)le16_to_cpu(ie->data.vi.data_offset) +
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le16_to_cpu(ie->data.vi.data_length) >
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le16_to_cpu(ie->length))
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goto idx_err_out;
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/* If the keys match perfectly, we setup @ictx and return 0. */
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if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
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&ie->key, key_len)) {
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ir_done:
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ictx->is_in_root = true;
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ictx->ir = ir;
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ictx->actx = actx;
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ictx->base_ni = base_ni;
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ictx->ia = NULL;
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ictx->page = NULL;
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done:
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ictx->entry = ie;
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ictx->data = (u8*)ie +
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le16_to_cpu(ie->data.vi.data_offset);
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ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
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ntfs_debug("Done.");
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return err;
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}
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/*
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* Not a perfect match, need to do full blown collation so we
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* know which way in the B+tree we have to go.
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*/
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rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
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key_len, &ie->key, le16_to_cpu(ie->key_length));
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/*
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* |