/*
   * index.h - Defines for NTFS kernel index handling.  Part of the Linux-NTFS
   *	     project.
   *
   * Copyright (c) 2004 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
   */
  
  #ifndef _LINUX_NTFS_INDEX_H
  #define _LINUX_NTFS_INDEX_H
  
  #include <linux/fs.h>
  
  #include "types.h"
  #include "layout.h"
  #include "inode.h"
  #include "attrib.h"
  #include "mft.h"
  #include "aops.h"
  
  /**
   * @idx_ni:	index inode containing the @entry described by this context
   * @entry:	index entry (points into @ir or @ia)
   * @data:	index entry data (points into @entry)
   * @data_len:	length in bytes of @data

   * @is_in_root:	'true' if @entry is in @ir and 'false' if it is in @ia

   * @ir:		index root if @is_in_root and NULL otherwise
   * @actx:	attribute search context if @is_in_root and NULL otherwise
   * @base_ni:	base inode if @is_in_root and NULL otherwise

   * @ia:		index block if @is_in_root is 'false' and NULL otherwise
   * @page:	page if @is_in_root is 'false' and NULL otherwise

   *
   * @idx_ni is the index inode this context belongs to.
   *
   * @entry is the index entry described by this context.  @data and @data_len
   * are the index entry data and its length in bytes, respectively.  @data
   * simply points into @entry.  This is probably what the user is interested in.
   *

   * If @is_in_root is 'true', @entry is in the index root attribute @ir described

   * by the attribute search context @actx and the base inode @base_ni.  @ia and
   * @page are NULL in this case.
   *

   * If @is_in_root is 'false', @entry is in the index allocation attribute and @ia

   * and @page point to the index allocation block and the mapped, locked page it
   * is in, respectively.  @ir, @actx and @base_ni are NULL in this case.
   *
   * To obtain a context call ntfs_index_ctx_get().
   *
   * We use this context to allow ntfs_index_lookup() to return the found index
   * @entry and its @data without having to allocate a buffer and copy the @entry
   * and/or its @data into it.
   *
   * 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.
   */
  typedef struct {
  	ntfs_inode *idx_ni;
  	INDEX_ENTRY *entry;
  	void *data;
  	u16 data_len;

  	bool is_in_root;

  	INDEX_ROOT *ir;
  	ntfs_attr_search_ctx *actx;
  	ntfs_inode *base_ni;
  	INDEX_ALLOCATION *ia;
  	struct page *page;
  } ntfs_index_context;
  
  extern ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni);
  extern void ntfs_index_ctx_put(ntfs_index_context *ictx);
  
  extern int ntfs_index_lookup(const void *key, const int key_len,
  		ntfs_index_context *ictx);
  
  #ifdef NTFS_RW
  
  /**
   * ntfs_index_entry_flush_dcache_page - flush_dcache_page() for index entries
   * @ictx:	ntfs index context describing the index entry
   *
   * Call flush_dcache_page() for the page in which an index entry resides.
   *
   * This must be called every time an index entry is modified, just after the
   * modification.
   *
   * If the index entry is in the index root attribute, simply flush the page
   * containing the mft record containing the index root attribute.
   *
   * If the index entry is in an index block belonging to the index allocation
   * attribute, simply flush the page cache page containing the index block.
   */
  static inline void ntfs_index_entry_flush_dcache_page(ntfs_index_context *ictx)
  {
  	if (ictx->is_in_root)
  		flush_dcache_mft_record_page(ictx->actx->ntfs_ino);
  	else
  		flush_dcache_page(ictx->page);
  }
  
  /**
   * ntfs_index_entry_mark_dirty - mark an index entry dirty
   * @ictx:	ntfs index context describing the index entry
   *
   * Mark the index entry described by the index entry context @ictx dirty.
   *
   * If the index entry is in the index root attribute, simply mark the mft
   * record containing the index root attribute dirty.  This ensures the mft
   * record, and hence the index root attribute, will be written out to disk
   * later.
   *
   * If the index entry is in an index block belonging to the index allocation
   * attribute, mark the buffers belonging to the index record as well as the
   * page cache page the index block is in dirty.  This automatically marks the
   * VFS inode of the ntfs index inode to which the index entry belongs dirty,
   * too (I_DIRTY_PAGES) and this in turn ensures the page buffers, and hence the
   * dirty index block, will be written out to disk later.
   */
  static inline void ntfs_index_entry_mark_dirty(ntfs_index_context *ictx)
  {
  	if (ictx->is_in_root)
  		mark_mft_record_dirty(ictx->actx->ntfs_ino);
  	else
  		mark_ntfs_record_dirty(ictx->page,
  				(u8*)ictx->ia - (u8*)page_address(ictx->page));
  }
  
  #endif /* NTFS_RW */
  
  #endif /* _LINUX_NTFS_INDEX_H */