[RFC PATCH 4/7] ext2: Use dax_is_supported()

[Mathieu Desnoyers]

Use dax_is_supported() to validate whether the architecture has
virtually aliased caches at mount time.

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

Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: nvdimm@xxxxxxxxxxxxxxx
Cc: linux-cxl@xxxxxxxxxxxxxxx
---
 fs/ext2/super.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 01f9addc8b1f..0398e7a90eb6 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -585,13 +585,13 @@ static int parse_options(char *options, struct super_block *sb,
 			set_opt(opts->s_mount_opt, XIP);
 			fallthrough;
 		case Opt_dax:
-#ifdef CONFIG_FS_DAX
-			ext2_msg(sb, KERN_WARNING,
-		"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
-			set_opt(opts->s_mount_opt, DAX);
-#else
-			ext2_msg(sb, KERN_INFO, "dax option not supported");
-#endif
+			if (dax_is_supported()) {
+				ext2_msg(sb, KERN_WARNING,
+					 "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
+				set_opt(opts->s_mount_opt, DAX);
+			} else {
+				ext2_msg(sb, KERN_INFO, "dax option not supported");
+			}
 			break;
 
 #if defined(CONFIG_QUOTA)
-- 
2.39.2