[PATCH v3 5/9] mm/internal: rename swap offset helpers to softleaf offset

[Dev Jain]

In preparation for adding a helper to set softleaf PTEs in one go,
generalize the helpers that advance a swap-entry offset so they operate
on softleaf entries.

Softleaf entries use the same type/offset layout as swap entries, so
advancing the offset works for swap softleaves and PFN-bearing
softleaves. Preserve soft-dirty and uffd bits across the move. The
swap-exclusive bit is meaningful only for swap softleaves, so guard that
preservation with softleaf_is_swap().

Reviewed-by: Barry Song <baohua@xxxxxxxxxx>
Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
---
 mm/internal.h | 31 ++++++++++++++++---------------
 mm/memory.c   |  4 ++--
 2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 3b9fdb826162d..b8ec379b90bb0 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -469,16 +469,16 @@ unsigned int folio_pte_batch(struct folio *folio, pte_t *ptep, pte_t pte,
 		unsigned int max_nr);
 
 /**
- * pte_move_swp_offset - Move the swap entry offset field of a swap pte
- *	 forward or backward by delta
- * @pte: The initial pte state; must be a swap entry
+ * pte_move_softleaf_offset - Move the softleaf entry offset field of a
+ * softleaf pte forward or backward by delta
+ * @pte: The initial pte state; must be a softleaf entry
  * @delta: The direction and the offset we are moving; forward if delta
  *	 is positive; backward if delta is negative
  *
- * Moves the swap offset, while maintaining all other fields, including
- * swap type, and any swp pte bits. The resulting pte is returned.
+ * Moves the softleaf offset, while maintaining all other fields, including
+ * softleaf type, and any softleaf pte bits. The resulting pte is returned.
  */
-static inline pte_t pte_move_swp_offset(pte_t pte, long delta)
+static inline pte_t pte_move_softleaf_offset(pte_t pte, long delta)
 {
 	const softleaf_t entry = softleaf_from_pte(pte);
 	pte_t new = __swp_entry_to_pte(__swp_entry(swp_type(entry),
@@ -486,7 +486,7 @@ static inline pte_t pte_move_swp_offset(pte_t pte, long delta)
 
 	if (pte_swp_soft_dirty(pte))
 		new = pte_swp_mksoft_dirty(new);
-	if (pte_swp_exclusive(pte))
+	if (softleaf_is_swap(entry) && pte_swp_exclusive(pte))
 		new = pte_swp_mkexclusive(new);
 	if (pte_swp_uffd(pte))
 		new = pte_swp_mkuffd(new);
@@ -496,15 +496,16 @@ static inline pte_t pte_move_swp_offset(pte_t pte, long delta)
 
 
 /**
- * pte_next_swp_offset - Increment the swap entry offset field of a swap pte.
- * @pte: The initial pte state; must be a swap entry.
+ * pte_next_softleaf_offset - Increment the softleaf entry offset field of a
+ * non-present pte.
+ * @pte: The initial pte state; must be a softleaf entry.
  *
- * Increments the swap offset, while maintaining all other fields, including
- * swap type, and any swp pte bits. The resulting pte is returned.
+ * Increments the softleaf offset, while maintaining all other fields, including
+ * softleaf type, and any softleaf pte bits. The resulting pte is returned.
  */
-static inline pte_t pte_next_swp_offset(pte_t pte)
+static inline pte_t pte_next_softleaf_offset(pte_t pte)
 {
-	return pte_move_swp_offset(pte, 1);
+	return pte_move_softleaf_offset(pte, 1);
 }
 
 /**
@@ -524,7 +525,7 @@ static inline pte_t pte_next_swp_offset(pte_t pte)
  */
 static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte)
 {
-	pte_t expected_pte = pte_next_swp_offset(pte);
+	pte_t expected_pte = pte_next_softleaf_offset(pte);
 	const pte_t *end_ptep = start_ptep + max_nr;
 	pte_t *ptep = start_ptep + 1;
 
@@ -536,7 +537,7 @@ static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte)
 
 		if (!pte_same(pte, expected_pte))
 			break;
-		expected_pte = pte_next_swp_offset(expected_pte);
+		expected_pte = pte_next_softleaf_offset(expected_pte);
 		ptep++;
 	}
 
diff --git a/mm/memory.c b/mm/memory.c
index a7e979bfc814b..60fd0a08b35f5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4816,7 +4816,7 @@ static bool can_swapin_thp(struct vm_fault *vmf, pte_t *ptep, int nr_pages)
 	idx = (vmf->address - addr) / PAGE_SIZE;
 	pte = ptep_get(ptep);
 
-	if (!pte_same(pte, pte_move_swp_offset(vmf->orig_pte, -idx)))
+	if (!pte_same(pte, pte_move_softleaf_offset(vmf->orig_pte, -idx)))
 		return false;
 	/*
 	 * swap_read_folio() can't handle the case a large folio is hybridly
@@ -5131,7 +5131,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 
 		folio_ptep = vmf->pte - idx;
 		folio_pte = ptep_get(folio_ptep);
-		if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
+		if (!pte_same(folio_pte, pte_move_softleaf_offset(vmf->orig_pte, -idx)) ||
 		    swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
 			goto check_folio;
 
-- 
2.43.0