diff options
Diffstat (limited to 'drivers/md/persistent-data/dm-btree.h')
| -rw-r--r-- | drivers/md/persistent-data/dm-btree.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/drivers/md/persistent-data/dm-btree.h b/drivers/md/persistent-data/dm-btree.h index c74301fa5a37..db9bd26adf31 100644 --- a/drivers/md/persistent-data/dm-btree.h +++ b/drivers/md/persistent-data/dm-btree.h @@ -176,4 +176,39 @@ int dm_btree_walk(struct dm_btree_info *info, dm_block_t root, int (*fn)(void *context, uint64_t *keys, void *leaf), void *context); + +/*----------------------------------------------------------------*/ + +/* + * Cursor API. This does not follow the rolling lock convention. Since we + * know the order that values are required we can issue prefetches to speed + * up iteration. Use on a single level btree only. + */ +#define DM_BTREE_CURSOR_MAX_DEPTH 16 + +struct cursor_node { + struct dm_block *b; + unsigned index; +}; + +struct dm_btree_cursor { + struct dm_btree_info *info; + dm_block_t root; + + bool prefetch_leaves; + unsigned depth; + struct cursor_node nodes[DM_BTREE_CURSOR_MAX_DEPTH]; +}; + +/* + * Creates a fresh cursor. If prefetch_leaves is set then it is assumed + * the btree contains block indexes that will be prefetched. The cursor is + * quite large, so you probably don't want to put it on the stack. + */ +int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root, + bool prefetch_leaves, struct dm_btree_cursor *c); +void dm_btree_cursor_end(struct dm_btree_cursor *c); +int dm_btree_cursor_next(struct dm_btree_cursor *c); +int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le); + #endif /* _LINUX_DM_BTREE_H */ |