fs/ntfs/index.h

   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  */
  75 typedef 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
  88 extern ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni);
  89 extern void ntfs_index_ctx_put(ntfs_index_context *ictx);
  90
  91 extern 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  */
 111 static 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  */
 137 static 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 */