Hi Christoph Hellwig, Thank you for your comment. > On Fri, Mar 25, 2022 at 03:00:55AM +0000, Yuezhang.Mo@xxxxxxxx wrote: > > +#include <linux/blk_types.h> > > blk_types.h is not a header for public use. What do you want it for? + struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping; The type of 'sb->s_bdev' is 'struct block_device'. I want to include the definition of 'struct block_device'('struct block_device' is defined in <linux/blk_types.h>). Should I change to include <linux/blkdev.h>? Best Regards, Yuezhang Mo