linux-kernel - [PATCH v3 2/7] fs/dax: Use folio_split

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Message-ID: <20260109085605.443316-3-francois.dugast@intel.com>
Date: Fri,  9 Jan 2026 09:54:22 +0100
From: Francois Dugast <francois.dugast@...el.com>
To: intel-xe@...ts.freedesktop.org
Cc: dri-devel@...ts.freedesktop.org,
	Matthew Brost <matthew.brost@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Matthew Wilcox <willy@...radead.org>,
	Jan Kara <jack@...e.cz>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	linux-fsdevel@...r.kernel.org,
	nvdimm@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Alistair Popple <apopple@...dia.com>,
	Francois Dugast <francois.dugast@...el.com>
Subject: [PATCH v3 2/7] fs/dax: Use folio_split_unref helper

From: Matthew Brost <matthew.brost@...el.com>

Use folio_split_unref helper to split a folio into individual upon final
put of a fsdax page.

Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Jan Kara <jack@...e.cz>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org
Cc: nvdimm@...ts.linux.dev
Cc: linux-kernel@...r.kernel.org
Suggested-by: Alistair Popple <apopple@...dia.com>
Signed-off-by: Matthew Brost <matthew.brost@...el.com>
Signed-off-by: Francois Dugast <francois.dugast@...el.com>
---
 fs/dax.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 289e6254aa30..90ec68785f40 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -381,7 +381,6 @@ static void dax_folio_make_shared(struct folio *folio)
 static inline unsigned long dax_folio_put(struct folio *folio)
 {
 	unsigned long ref;
-	int order, i;
 
 	if (!dax_folio_is_shared(folio))
 		ref = 0;
@@ -391,29 +390,7 @@ static inline unsigned long dax_folio_put(struct folio *folio)
 	if (ref)
 		return ref;
 
-	folio->mapping = NULL;
-	order = folio_order(folio);
-	if (!order)
-		return 0;
-	folio_reset_order(folio);
-
-	for (i = 0; i < (1UL << order); i++) {
-		struct dev_pagemap *pgmap = page_pgmap(&folio->page);
-		struct page *page = folio_page(folio, i);
-		struct folio *new_folio = (struct folio *)page;
-
-		ClearPageHead(page);
-		clear_compound_head(page);
-
-		new_folio->mapping = NULL;
-		/*
-		 * Reset pgmap which was over-written by
-		 * prep_compound_page().
-		 */
-		new_folio->pgmap = pgmap;
-		new_folio->share = 0;
-		WARN_ON_ONCE(folio_ref_count(new_folio));
-	}
+	folio_split_unref(folio);
 
 	return ref;
 }
-- 
2.43.0