mm: remove page_file_offset and folio_file_pos

These two helpers were useful for mixed usage of swap cache and page
cache, which help retrieve the corresponding file or swap device offset of
a page or folio.

They were introduced in commit f981c5950fa8 ("mm: methods for teaching
filesystems about PG_swapcache pages") and used in commit d56b4ddf7781
("nfs: teach the NFS client how to treat PG_swapcache pages"), suppose to
be used with direct_IO for swap over fs.

But after commit e1209d3a7a67 ("mm: introduce ->swap_rw and use it for
reads from SWP_FS_OPS swap-space"), swap with direct_IO is no more, and
swap cache mapping is never exposed to fs.

Now we have dropped all users of page_file_offset and folio_file_pos, so
they can be deleted.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kairui Song <[email protected]>
Reviewed-by: "Huang, Ying" <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Li <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Marc Dionne <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Ryusuke Konishi <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Xiubo Li <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions