1. If some file's size is 5000 Bytes, then the first 4096 Bytes are read by the first page, the remaining 4 Bytes are read by the second page. What is fetched in the left 4092 Bytes in the second page space?

2. How can I check the offset of the data (eg. the remaining 4 Bytes's location)
I found there is a macro named "bio_offset", but it's parameter is bio, not page.

3. When reading files, how can I check where each page is from (the file path and the file name)
Can the file name be found through struct file->f_dentry->d_name.name?

4. in function mpage_end_io_read,
struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
so pointer bvec is pointed to the last "bio_vec"，then "--bvec", and I don't why doing it reversely?