linux-kernel - [RFC PATCH v2 5/8] fuse: Use dax_is

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Date: Tue, 30 Jan 2024 11:52:52 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Dan Williams <dan.j.williams@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Dave Jiang <dave.jiang@...el.com>
Cc: linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Miklos Szeredi <miklos@...redi.hu>,
	linux-fsdevel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-mm@...ck.org,
	linux-arch@...r.kernel.org,
	Matthew Wilcox <willy@...radead.org>,
	Arnd Bergmann <arnd@...db.de>,
	Russell King <linux@...linux.org.uk>,
	nvdimm@...ts.linux.dev,
	linux-cxl@...r.kernel.org
Subject: [RFC PATCH v2 5/8] fuse: Use dax_is_supported()

Use dax_is_supported() to validate whether the architecture has
virtually aliased data caches at mount time. Silently disable
DAX if dax=always is requested as a mount option on an architecture
which does not support DAX.

This is relevant for architectures which require a dynamic check
to validate whether they have virtually aliased data caches.

Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Miklos Szeredi <miklos@...redi.hu>
Cc: linux-fsdevel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-mm@...ck.org
Cc: linux-arch@...r.kernel.org
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Vishal Verma <vishal.l.verma@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Russell King <linux@...linux.org.uk>
Cc: nvdimm@...ts.linux.dev
Cc: linux-cxl@...r.kernel.org
---
 fs/fuse/dax.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 12ef91d170bb..36e1c1abbf8e 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -1336,6 +1336,13 @@ static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags)
 	if (dax_mode == FUSE_DAX_NEVER)
 		return false;
 
+	/*
+	 * Silently fallback to 'never' mode if the architecture does
+	 * not support DAX.
+	 */
+	if (!dax_is_supported())
+		return false;
+
 	/*
 	 * fc->dax may be NULL in 'inode' mode when filesystem device doesn't
 	 * support DAX, in which case it will silently fallback to 'never' mode.
-- 
2.39.2