change bitmap superblock struct and corriesponding memory struct

Signed-off-by: Bo Yang <boyang@suse.com>
add dlm interface to lock mddev

Signed-off-by: Bo Yang <boyang@suse.com>
bitmap add internal funtions

	exist_in_avail_bitmap
	bitmap_add_avail_bitmap
	exist_in_reclaim_bitmap
	bitmap_add_reclaim_bitmap
	find_bitmap_by_node
	bitmap_ast
	bitmap_bast
	bitmap_sync_ast
	bitmap_sync_bast
	bitmap_lock_sync
	bitmap_unlock_sync
	bitmap_lock_async
change write_sb_page in bitmap.c
change bitmap_read_sb in bitmap.c
change file_page_index in bitmap.c
change file_page_offset in bitmap.c
change filemap_get_page in bitmap.c
change bitmap_file_set_bit in bitmap.c
change bitmap_file_clear_bit in bitmap.c
change bitmap_unplug in bitmap.c
change bitmap_init_from_disk in bitmap.c
change bitmap_count_page in bitmap.c
change bitmap_set_pending in bitmap.c
change bitmap_daemon_work in bitmap.c
change bitmap_get_counter in bitmap.c
change bitmap_startwrite in bitmap.c
change bitmap_endwrite in bitmap.c
change bitmap_start_sync in bitmap.c
change bitmap_end_sync in bitmap.c