linux-kernel - [PATCH v3 7/7] mm/swap: refactor swap_cache_get

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Message-ID: <20240129175423.1987-8-ryncsn@gmail.com>
Date: Tue, 30 Jan 2024 01:54:22 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Chris Li <chrisl@...nel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Matthew Wilcox <willy@...radead.org>,
	Michal Hocko <mhocko@...e.com>,
	Yosry Ahmed <yosryahmed@...gle.com>,
	David Hildenbrand <david@...hat.com>,
	linux-kernel@...r.kernel.org,
	Kairui Song <kasong@...cent.com>
Subject: [PATCH v3 7/7] mm/swap: refactor swap_cache_get_folio

From: Kairui Song <kasong@...cent.com>

No feature change, change the code layout to reduce object size
and kill redundant indent.

With gcc 13.2.1:

/scripts/bloat-o-meter mm/swap_state.o.old mm/swap_state.o
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-35 (-35)
Function                                     old     new   delta
swap_cache_get_folio                         380     345     -35
Total: Before=8785, After=8750, chg -0.40%

Signed-off-by: Kairui Song <kasong@...cent.com>
---
 mm/swap_state.c | 59 ++++++++++++++++++++++++-------------------------
 1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 20c206149be4..2f809b69b65a 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -341,9 +341,10 @@ static inline bool swap_use_vma_readahead(void)
  *
  * Caller must lock the swap device or hold a reference to keep it valid.
  */
-struct folio *swap_cache_get_folio(swp_entry_t entry,
-		struct vm_area_struct *vma, unsigned long addr, void **shadowp)
+struct folio *swap_cache_get_folio(swp_entry_t entry, struct vm_area_struct *vma,
+				   unsigned long addr, void **shadowp)
 {
+	bool vma_ra, readahead;
 	struct folio *folio;
 
 	folio = filemap_get_entry(swap_address_space(entry), swp_offset(entry));
@@ -352,37 +353,35 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
 			*shadowp = folio;
 		return NULL;
 	}
+	if (!folio)
+		return NULL;
 
-	if (folio) {
-		bool vma_ra = swap_use_vma_readahead();
-		bool readahead;
+	/*
+	 * At the moment, we don't support PG_readahead for anon THP
+	 * so let's bail out rather than confusing the readahead stat.
+	 */
+	if (unlikely(folio_test_large(folio)))
+		return folio;
 
-		/*
-		 * At the moment, we don't support PG_readahead for anon THP
-		 * so let's bail out rather than confusing the readahead stat.
-		 */
-		if (unlikely(folio_test_large(folio)))
-			return folio;
-
-		readahead = folio_test_clear_readahead(folio);
-		if (vma && vma_ra) {
-			unsigned long ra_val;
-			int win, hits;
-
-			ra_val = GET_SWAP_RA_VAL(vma);
-			win = SWAP_RA_WIN(ra_val);
-			hits = SWAP_RA_HITS(ra_val);
-			if (readahead)
-				hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
-			atomic_long_set(&vma->swap_readahead_info,
-					SWAP_RA_VAL(addr, win, hits));
-		}
+	vma_ra = swap_use_vma_readahead();
+	readahead = folio_test_clear_readahead(folio);
+	if (vma && vma_ra) {
+		unsigned long ra_val;
+		int win, hits;
+
+		ra_val = GET_SWAP_RA_VAL(vma);
+		win = SWAP_RA_WIN(ra_val);
+		hits = SWAP_RA_HITS(ra_val);
+		if (readahead)
+			hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
+		atomic_long_set(&vma->swap_readahead_info,
+				SWAP_RA_VAL(addr, win, hits));
+	}
 
-		if (readahead) {
-			count_vm_event(SWAP_RA_HIT);
-			if (!vma || !vma_ra)
-				atomic_inc(&swapin_readahead_hits);
-		}
+	if (readahead) {
+		count_vm_event(SWAP_RA_HIT);
+		if (!vma || !vma_ra)
+			atomic_inc(&swapin_readahead_hits);
 	}
 
 	return folio;
-- 
2.43.0