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ocfs2: Comment struct ocfs2_extent_tree_operations. 

struct ocfs2_extent_tree_operations provides methods for the different
on-disk btrees in ocfs2.  Describing what those methods do is probably a
good idea.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This commit is contained in:
Joel Becker 2008-08-21 17:11:10 -07:00 committed by Mark Fasheh
parent f99b9b7ccf
commit 1625f8ac15
1 changed files with 43 additions and 2 deletions
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45
fs/ocfs2/alloc.c
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@ -50,21 +50,62 @@
#include "buffer_head_io.h"
/*
* Operations for a specific extent tree type.
*
* To implement an on-disk btree (extent tree) type in ocfs2, add
* an ocfs2_extent_tree_operations structure and the matching
* ocfs2_get_<thingy>_extent_tree() function. That's pretty much it
* for the allocation portion of the extent tree.
*/
struct ocfs2_extent_tree_operations {
/*
* last_eb_blk is the block number of the right most leaf extent
* block. Most on-disk structures containing an extent tree store
* this value for fast access. The ->eo_set_last_eb_blk() and
* ->eo_get_last_eb_blk() operations access this value. They are
* both required.
*/
void (*eo_set_last_eb_blk)(struct ocfs2_extent_tree *et,
u64 blkno);
u64 (*eo_get_last_eb_blk)(struct ocfs2_extent_tree *et);
/*
* The on-disk structure usually keeps track of how many total
* clusters are stored in this extent tree. This function updates
* that value. new_clusters is the delta, and must be
* added to the total. Required.
*/
void (*eo_update_clusters)(struct inode *inode,
struct ocfs2_extent_tree *et,
u32 new_clusters);
/*
* If ->eo_insert_check() exists, it is called before rec is
* inserted into the extent tree. It is optional.
*/
int (*eo_insert_check)(struct inode *inode,
struct ocfs2_extent_tree *et,
struct ocfs2_extent_rec *rec);
int (*eo_sanity_check)(struct inode *inode, struct ocfs2_extent_tree *et);
/* These are internal to ocfs2_extent_tree and don't have
* accessor functions */
/*
* --------------------------------------------------------------
* The remaining are internal to ocfs2_extent_tree and don't have
* accessor functions
*/
/*
* ->eo_fill_root_el() takes et->et_object and sets et->et_root_el.
* It is required.
*/
void (*eo_fill_root_el)(struct ocfs2_extent_tree *et);
/*
* ->eo_fill_max_leaf_clusters sets et->et_max_leaf_clusters if
* it exists. If it does not, et->et_max_leaf_clusters is set
* to 0 (unlimited). Optional.
*/
void (*eo_fill_max_leaf_clusters)(struct inode *inode,
struct ocfs2_extent_tree *et);
};