void unmap_mft_record_page (ntfs_inode * ni);
This unmaps the page in which the mft record of the ntfs inode ni is situated and returns. This is a NOOP if highmem is not configured.
The unmap happens via ntfs_unmap_page which in turn decrements the use count on the page thus releasing it from the pinned state.
We do not actually unmap the page from memory of course, as that will be done by the page cache code itself when memory pressure increases or whatever.