linux/fs/ntfs/index.h
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   1/*
   2 * index.h - Defines for NTFS kernel index handling.  Part of the Linux-NTFS
   3 *           project.
   4 *
   5 * Copyright (c) 2004 Anton Altaparmakov
   6 *
   7 * This program/include file is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as published
   9 * by the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program/include file is distributed in the hope that it will be
  13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program (in the main directory of the Linux-NTFS
  19 * distribution in the file COPYING); if not, write to the Free Software
  20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 */
  22
  23#ifndef _LINUX_NTFS_INDEX_H
  24#define _LINUX_NTFS_INDEX_H
  25
  26#include <linux/fs.h>
  27
  28#include "types.h"
  29#include "layout.h"
  30#include "inode.h"
  31#include "attrib.h"
  32#include "mft.h"
  33#include "aops.h"
  34
  35/**
  36 * @idx_ni:     index inode containing the @entry described by this context
  37 * @entry:      index entry (points into @ir or @ia)
  38 * @data:       index entry data (points into @entry)
  39 * @data_len:   length in bytes of @data
  40 * @is_in_root: 'true' if @entry is in @ir and 'false' if it is in @ia
  41 * @ir:         index root if @is_in_root and NULL otherwise
  42 * @actx:       attribute search context if @is_in_root and NULL otherwise
  43 * @base_ni:    base inode if @is_in_root and NULL otherwise
  44 * @ia:         index block if @is_in_root is 'false' and NULL otherwise
  45 * @page:       page if @is_in_root is 'false' and NULL otherwise
  46 *
  47 * @idx_ni is the index inode this context belongs to.
  48 *
  49 * @entry is the index entry described by this context.  @data and @data_len
  50 * are the index entry data and its length in bytes, respectively.  @data
  51 * simply points into @entry.  This is probably what the user is interested in.
  52 *
  53 * If @is_in_root is 'true', @entry is in the index root attribute @ir described
  54 * by the attribute search context @actx and the base inode @base_ni.  @ia and
  55 * @page are NULL in this case.
  56 *
  57 * If @is_in_root is 'false', @entry is in the index allocation attribute and @ia
  58 * and @page point to the index allocation block and the mapped, locked page it
  59 * is in, respectively.  @ir, @actx and @base_ni are NULL in this case.
  60 *
  61 * To obtain a context call ntfs_index_ctx_get().
  62 *
  63 * We use this context to allow ntfs_index_lookup() to return the found index
  64 * @entry and its @data without having to allocate a buffer and copy the @entry
  65 * and/or its @data into it.
  66 *
  67 * When finished with the @entry and its @data, call ntfs_index_ctx_put() to
  68 * free the context and other associated resources.
  69 *
  70 * If the index entry was modified, call flush_dcache_index_entry_page()
  71 * immediately after the modification and either ntfs_index_entry_mark_dirty()
  72 * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
  73 * ensure that the changes are written to disk.
  74 */
  75typedef struct {
  76        ntfs_inode *idx_ni;
  77        INDEX_ENTRY *entry;
  78        void *data;
  79        u16 data_len;
  80        bool is_in_root;
  81        INDEX_ROOT *ir;
  82        ntfs_attr_search_ctx *actx;
  83        ntfs_inode *base_ni;
  84        INDEX_ALLOCATION *ia;
  85        struct page *page;
  86} ntfs_index_context;
  87
  88extern ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni);
  89extern void ntfs_index_ctx_put(ntfs_index_context *ictx);
  90
  91extern int ntfs_index_lookup(const void *key, const int key_len,
  92                ntfs_index_context *ictx);
  93
  94#ifdef NTFS_RW
  95
  96/**
  97 * ntfs_index_entry_flush_dcache_page - flush_dcache_page() for index entries
  98 * @ictx:       ntfs index context describing the index entry
  99 *
 100 * Call flush_dcache_page() for the page in which an index entry resides.
 101 *
 102 * This must be called every time an index entry is modified, just after the
 103 * modification.
 104 *
 105 * If the index entry is in the index root attribute, simply flush the page
 106 * containing the mft record containing the index root attribute.
 107 *
 108 * If the index entry is in an index block belonging to the index allocation
 109 * attribute, simply flush the page cache page containing the index block.
 110 */
 111static inline void ntfs_index_entry_flush_dcache_page(ntfs_index_context *ictx)
 112{
 113        if (ictx->is_in_root)
 114                flush_dcache_mft_record_page(ictx->actx->ntfs_ino);
 115        else
 116                flush_dcache_page(ictx->page);
 117}
 118
 119/**
 120 * ntfs_index_entry_mark_dirty - mark an index entry dirty
 121 * @ictx:       ntfs index context describing the index entry
 122 *
 123 * Mark the index entry described by the index entry context @ictx dirty.
 124 *
 125 * If the index entry is in the index root attribute, simply mark the mft
 126 * record containing the index root attribute dirty.  This ensures the mft
 127 * record, and hence the index root attribute, will be written out to disk
 128 * later.
 129 *
 130 * If the index entry is in an index block belonging to the index allocation
 131 * attribute, mark the buffers belonging to the index record as well as the
 132 * page cache page the index block is in dirty.  This automatically marks the
 133 * VFS inode of the ntfs index inode to which the index entry belongs dirty,
 134 * too (I_DIRTY_PAGES) and this in turn ensures the page buffers, and hence the
 135 * dirty index block, will be written out to disk later.
 136 */
 137static inline void ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
 138{
 139        if (ictx->is_in_root)
 140                mark_mft_record_dirty(ictx->actx->ntfs_ino);
 141        else
 142                mark_ntfs_record_dirty(ictx->page,
 143                                (u8*)ictx->ia - (u8*)page_address(ictx->page));
 144}
 145
 146#endif /* NTFS_RW */
 147
 148#endif /* _LINUX_NTFS_INDEX_H */
 149
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