[RFC PATCH 03/10] mm/swap: convert swapin_readahead to return a folio

Kairui Song
2024-03-26T19:04:30Z

From: Kairui Song <kasong@tencent.com>

Simplify the caller code logic.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
mm/memory.c | 8 +++-----
mm/swap.h | 4 ++--
mm/swap_state.c | 6 ++----
mm/swapfile.c | 5 +----
4 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index e42fadc25268..dfdb620a9123 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4005,12 +4005,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
if (PTR_ERR(folio) == -EBUSY)
goto out;
need_clear_cache = true;
- page = &folio->page;
} else {
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
- vmf);
- if (page)
- folio = page_folio(page);
+ folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vmf);
swapcache = folio;
}

@@ -4027,6 +4023,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
goto unlock;
}

+ page = folio_file_page(folio, swp_offset(entry));
+
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
diff --git a/mm/swap.h b/mm/swap.h
index 40e902812cc5..aee134907a70 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -57,7 +57,7 @@ struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
struct mempolicy *mpol, pgoff_t ilx);
struct folio *swapin_direct(swp_entry_t entry, gfp_t flag,
struct vm_fault *vmf);
-struct page *swapin_readahead(swp_entry_t entry, gfp_t flag,
+struct folio *swapin_readahead(swp_entry_t entry, gfp_t flag,
struct vm_fault *vmf);

static inline unsigned int folio_swap_flags(struct folio *folio)
@@ -95,7 +95,7 @@ static inline struct folio *swapin_direct(swp_entry_t entry, gfp_t flag,
return NULL;
}

-static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
+static inline struct folio *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
struct vm_fault *vmf)
{
return NULL;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 0a3fa48b3893..2a9c6bdff5ea 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -951,7 +951,7 @@ struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask,
* it will read ahead blocks by cluster-based(ie, physical disk based)
* or vma-based(ie, virtual address based on faulty address) readahead.
*/
-struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
+struct folio *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
struct vm_fault *vmf)
{
struct mempolicy *mpol;
@@ -964,9 +964,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
swap_cluster_readahead(entry, gfp_mask, mpol, ilx);
mpol_cond_put(mpol);

- if (!folio)
- return NULL;
- return folio_file_page(folio, swp_offset(entry));
+ return folio;
}

#ifdef CONFIG_SYSFS
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 4919423cce76..4dd894395a0f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1883,7 +1883,6 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,

folio = swap_cache_get_folio(entry, vma, addr);
if (!folio) {
- struct page *page;
struct vm_fault vmf = {
.vma = vma,
.address = addr,
@@ -1891,10 +1890,8 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
.pmd = pmd,
};

- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
+ folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
&vmf);
- if (page)
- folio = page_folio(page);
}
if (!folio) {
swp_count = READ_ONCE(si->swap_map[offset]);
--
2.43.0