[RFC PATCH 5/7] ext4: Use dax_is_supported()

From: Mathieu Desnoyers
Date: Mon Jan 29 2024 - 16:08:48 EST


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: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
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/ext4/super.c | 52 ++++++++++++++++++++++++-------------------------
1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c5fcf377ab1f..9e0606289239 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2359,34 +2359,32 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param)
return ext4_parse_test_dummy_encryption(param, ctx);
case Opt_dax:
case Opt_dax_type:
-#ifdef CONFIG_FS_DAX
- {
- int type = (token == Opt_dax) ?
- Opt_dax : result.uint_32;
-
- switch (type) {
- case Opt_dax:
- case Opt_dax_always:
- ctx_set_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
- ctx_clear_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
- break;
- case Opt_dax_never:
- ctx_set_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
- ctx_clear_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
- break;
- case Opt_dax_inode:
- ctx_clear_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
- ctx_clear_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
- /* Strictly for printing options */
- ctx_set_mount_opt2(ctx, EXT4_MOUNT2_DAX_INODE);
- break;
+ if (dax_is_supported()) {
+ int type = (token == Opt_dax) ?
+ Opt_dax : result.uint_32;
+
+ switch (type) {
+ case Opt_dax:
+ case Opt_dax_always:
+ ctx_set_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
+ ctx_clear_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
+ break;
+ case Opt_dax_never:
+ ctx_set_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
+ ctx_clear_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
+ break;
+ case Opt_dax_inode:
+ ctx_clear_mount_opt(ctx, EXT4_MOUNT_DAX_ALWAYS);
+ ctx_clear_mount_opt2(ctx, EXT4_MOUNT2_DAX_NEVER);
+ /* Strictly for printing options */
+ ctx_set_mount_opt2(ctx, EXT4_MOUNT2_DAX_INODE);
+ break;
+ }
+ return 0;
+ } else {
+ ext4_msg(NULL, KERN_INFO, "dax option not supported");
+ return -EINVAL;
}
- return 0;
- }
-#else
- ext4_msg(NULL, KERN_INFO, "dax option not supported");
- return -EINVAL;
-#endif
case Opt_data_err:
if (result.uint_32 == Opt_data_err_abort)
ctx_set_mount_opt(ctx, m->mount_opt);
--
2.39.2