fs/ntfs/index.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * index.h - Defines for NTFS kernel index handling.  Part of the Linux-NTFS
   4  *           project.
   5  *
   6  * Copyright (c) 2004 Anton Altaparmakov
   7  */
   8
   9 #ifndef _LINUX_NTFS_INDEX_H
  10 #define _LINUX_NTFS_INDEX_H
  11
  12 #include <linux/fs.h>
  13
  14 #include "types.h"
  15 #include "layout.h"
  16 #include "inode.h"
  17 #include "attrib.h"
  18 #include "mft.h"
  19 #include "aops.h"
  20
  21 /**
  22  * @idx_ni:     index inode containing the @entry described by this context
  23  * @entry:      index entry (points into @ir or @ia)
  24  * @data:       index entry data (points into @entry)
  25  * @data_len:   length in bytes of @data
  26  * @is_in_root: 'true' if @entry is in @ir and 'false' if it is in @ia
  27  * @ir:         index root if @is_in_root and NULL otherwise
  28  * @actx:       attribute search context if @is_in_root and NULL otherwise
  29  * @base_ni:    base inode if @is_in_root and NULL otherwise
  30  * @ia:         index block if @is_in_root is 'false' and NULL otherwise
  31  * @page:       page if @is_in_root is 'false' and NULL otherwise
  32  *
  33  * @idx_ni is the index inode this context belongs to.
  34  *
  35  * @entry is the index entry described by this context.  @data and @data_len
  36  * are the index entry data and its length in bytes, respectively.  @data
  37  * simply points into @entry.  This is probably what the user is interested in.
  38  *
  39  * If @is_in_root is 'true', @entry is in the index root attribute @ir described
  40  * by the attribute search context @actx and the base inode @base_ni.  @ia and
  41  * @page are NULL in this case.
  42  *
  43  * If @is_in_root is 'false', @entry is in the index allocation attribute and @ia
  44  * and @page point to the index allocation block and the mapped, locked page it
  45  * is in, respectively.  @ir, @actx and @base_ni are NULL in this case.
  46  *
  47  * To obtain a context call ntfs_index_ctx_get().
  48  *
  49  * We use this context to allow ntfs_index_lookup() to return the found index
  50  * @entry and its @data without having to allocate a buffer and copy the @entry
  51  * and/or its @data into it.
  52  *
  53  * When finished with the @entry and its @data, call ntfs_index_ctx_put() to
  54  * free the context and other associated resources.
  55  *
  56  * If the index entry was modified, call flush_dcache_index_entry_page()
  57  * immediately after the modification and either ntfs_index_entry_mark_dirty()
  58  * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
  59  * ensure that the changes are written to disk.
  60  */
  61 typedef struct {
  62         ntfs_inode *idx_ni;
  63         INDEX_ENTRY *entry;
  64         void *data;
  65         u16 data_len;
  66         bool is_in_root;
  67         INDEX_ROOT *ir;
  68         ntfs_attr_search_ctx *actx;
  69         ntfs_inode *base_ni;
  70         INDEX_ALLOCATION *ia;
  71         struct page *page;
  72 } ntfs_index_context;
  73
  74 extern ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni);
  75 extern void ntfs_index_ctx_put(ntfs_index_context *ictx);
  76
  77 extern int ntfs_index_lookup(const void *key, const int key_len,
  78                 ntfs_index_context *ictx);
  79
  80 #ifdef NTFS_RW
  81
  82 /**
  83  * ntfs_index_entry_flush_dcache_page - flush_dcache_page() for index entries
  84  * @ictx:       ntfs index context describing the index entry
  85  *
  86  * Call flush_dcache_page() for the page in which an index entry resides.
  87  *
  88  * This must be called every time an index entry is modified, just after the
  89  * modification.
  90  *
  91  * If the index entry is in the index root attribute, simply flush the page
  92  * containing the mft record containing the index root attribute.
  93  *
  94  * If the index entry is in an index block belonging to the index allocation
  95  * attribute, simply flush the page cache page containing the index block.
  96  */
  97 static inline void ntfs_index_entry_flush_dcache_page(ntfs_index_context *ictx)
  98 {
  99         if (ictx->is_in_root)
 100                 flush_dcache_mft_record_page(ictx->actx->ntfs_ino);
 101         else
 102                 flush_dcache_page(ictx->page);
 103 }
 104
 105 /**
 106  * ntfs_index_entry_mark_dirty - mark an index entry dirty
 107  * @ictx:       ntfs index context describing the index entry
 108  *
 109  * Mark the index entry described by the index entry context @ictx dirty.
 110  *
 111  * If the index entry is in the index root attribute, simply mark the mft
 112  * record containing the index root attribute dirty.  This ensures the mft
 113  * record, and hence the index root attribute, will be written out to disk
 114  * later.
 115  *
 116  * If the index entry is in an index block belonging to the index allocation
 117  * attribute, mark the buffers belonging to the index record as well as the
 118  * page cache page the index block is in dirty.  This automatically marks the
 119  * VFS inode of the ntfs index inode to which the index entry belongs dirty,
 120  * too (I_DIRTY_PAGES) and this in turn ensures the page buffers, and hence the
 121  * dirty index block, will be written out to disk later.
 122  */
 123 static inline void ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
 124 {
 125         if (ictx->is_in_root)
 126                 mark_mft_record_dirty(ictx->actx->ntfs_ino);
 127         else
 128                 mark_ntfs_record_dirty(ictx->page,
 129                                 (u8*)ictx->ia - (u8*)page_address(ictx->page));
 130 }
 131
 132 #endif /* NTFS_RW */
 133
 134 #endif /* _LINUX_NTFS_INDEX_H */