mm: introduce pte_move_swp_offset() helper which can move offset bidirectionally

There could arise a necessity to obtain the first pte_t from a swap pte_t
located in the middle.  For instance, this may occur within the context of
do_swap_page(), where a page fault can potentially occur in any PTE of a
large folio.  To address this, the following patch introduces
pte_move_swp_offset(), a function capable of bidirectional movement by a
specified delta argument.  Consequently, pte_next_swp_offset() will
directly invoke it with delta = 1.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Suggested-by: "Huang, Ying" <[email protected]>
Reviewed-by: Ryan Roberts <[email protected]>
Reviewed-by: "Huang, Ying" <[email protected]>
Cc: Andreas Larsson <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Chris Li <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Chuanhua Han <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kairui Song <[email protected]>
Cc: Khalid Aziz <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions