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Commit fdd1315a authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm array: introduce cursor api 



More efficient way to iterate an array due to prefetching (makes use of
the new dm_btree_cursor_* api).

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 7d111c81

drivers/md/persistent-data/dm-array.c

+86 −0
Original line number Diff line number Diff line
@@ -899,3 +899,89 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root, 
EXPORT_SYMBOL_GPL(dm_array_walk);



/*----------------------------------------------------------------*/



static int load_ablock(struct dm_array_cursor *c)

{

	int r;

	__le64 value_le;

	uint64_t key;



	if (c->block)

		unlock_ablock(c->info, c->block);



	c->block = NULL;

	c->ab = NULL;

	c->index = 0;



	r = dm_btree_cursor_get_value(&c->cursor, &key, &value_le);

	if (r) {

		DMERR("dm_btree_cursor_get_value failed");

		dm_btree_cursor_end(&c->cursor);



	} else {

		r = get_ablock(c->info, le64_to_cpu(value_le), &c->block, &c->ab);

		if (r) {

			DMERR("get_ablock failed");

			dm_btree_cursor_end(&c->cursor);

		}

	}



	return r;

}



int dm_array_cursor_begin(struct dm_array_info *info, dm_block_t root,

			  struct dm_array_cursor *c)

{

	int r;



	memset(c, 0, sizeof(*c));

	c->info = info;

	r = dm_btree_cursor_begin(&info->btree_info, root, true, &c->cursor);

	if (r) {

		DMERR("couldn't create btree cursor");

		return r;

	}



	return load_ablock(c);

}

EXPORT_SYMBOL_GPL(dm_array_cursor_begin);



void dm_array_cursor_end(struct dm_array_cursor *c)

{

	if (c->block) {

		unlock_ablock(c->info, c->block);

		dm_btree_cursor_end(&c->cursor);

	}

}

EXPORT_SYMBOL_GPL(dm_array_cursor_end);



int dm_array_cursor_next(struct dm_array_cursor *c)

{

	int r;



	if (!c->block)

		return -ENODATA;



	c->index++;



	if (c->index >= le32_to_cpu(c->ab->nr_entries)) {

		r = dm_btree_cursor_next(&c->cursor);

		if (r)

			return r;



		r = load_ablock(c);

		if (r)

			return r;

	}



	return 0;

}

EXPORT_SYMBOL_GPL(dm_array_cursor_next);



void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le)

{

	*value_le = element_at(c->info, c->ab, c->index);

}

EXPORT_SYMBOL_GPL(dm_array_cursor_get_value);



/*----------------------------------------------------------------*/

drivers/md/persistent-data/dm-array.h

+33 −0
Original line number Diff line number Diff line
@@ -182,4 +182,37 @@ int dm_array_walk(struct dm_array_info *info, dm_block_t root, 


/*----------------------------------------------------------------*/



/*

 * Cursor api.

 *

 * This lets you iterate through all the entries in an array efficiently

 * (it will preload metadata).

 *

 * I'm using a cursor, rather than a walk function with a callback because

 * the cache target needs to iterate both the mapping and hint arrays in

 * unison.

 */

struct dm_array_cursor {

	struct dm_array_info *info;

	struct dm_btree_cursor cursor;



	struct dm_block *block;

	struct array_block *ab;

	unsigned index;

};



int dm_array_cursor_begin(struct dm_array_info *info,

			  dm_block_t root, struct dm_array_cursor *c);

void dm_array_cursor_end(struct dm_array_cursor *c);



uint32_t dm_array_cursor_index(struct dm_array_cursor *c);

int dm_array_cursor_next(struct dm_array_cursor *c);



/*

 * value_le is only valid while the cursor points at the current value.

 */

void dm_array_cursor_get_value(struct dm_array_cursor *c, void **value_le);



/*----------------------------------------------------------------*/



#endif	/* _LINUX_DM_ARRAY_H */