read_cache_page — read into page cache, fill it if needed
struct page * read_cache_page
(struct address_space * mapping, pgoff_t index, int (*filler)
(void *,struct page*), void * data);
the page's address_space
the page index
function to perform the read
destination for read data
Read into the page cache. If a page already exists, and PageUptodate is not set, try to fill the page then wait for it to become unlocked.
If the page does not get brought uptodate, return -EIO.