diff options
| -rw-r--r-- | fs/ocfs2/alloc.c | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c index 786a8298262..06b9bd73d6d 100644 --- a/fs/ocfs2/alloc.c +++ b/fs/ocfs2/alloc.c @@ -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); }; |