On Tue, Jan 30, 2024 at 11:52:48AM -0500, Mathieu Desnoyers wrote:
> Introduce a new dax_is_supported() static inline to check whether the
> architecture supports DAX.
>
> This replaces the following fs/Kconfig:FS_DAX dependency:
>
> depends on !(ARM || MIPS || SPARC)
>
> This is done in preparation for its use by each filesystem supporting
> the dax mount option to validate whether dax is indeed supported.
>
> This is done in preparation for using dcache_is_aliasing() in a
> following change which will properly support architectures which detect
> dcache aliasing at runtime.
>
> Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> 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: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> Cc: nvdimm@xxxxxxxxxxxxxxx
> Cc: linux-cxl@xxxxxxxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> ---
> fs/Kconfig | 1 -
> include/linux/dax.h | 10 ++++++++++
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 42837617a55b..e5efdb3b276b 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -56,7 +56,6 @@ endif # BLOCK
> config FS_DAX
> bool "File system based Direct Access (DAX) support"
> depends on MMU
> - depends on !(ARM || MIPS || SPARC)
> depends on ZONE_DEVICE || FS_DAX_LIMITED
> select FS_IOMAP
> select DAX
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index b463502b16e1..cfc8cd4a3eae 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -78,6 +78,12 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
> return false;
> return dax_synchronous(dax_dev);
> }
> +static inline bool dax_is_supported(void)
> +{
> + return !IS_ENABLED(CONFIG_ARM) &&
> + !IS_ENABLED(CONFIG_MIPS) &&
> + !IS_ENABLED(CONFIG_SPARC);
> +}
Uh, ok. Now I see what dax_is_supported() does.
I think this should be folded into fs_dax_get_by_bdev(), which
currently returns NULL if CONFIG_FS_DAX=n and so should be cahnged
to return NULL if any of these platform configs is enabled.
Then I don't think you need to change a single line of filesystem
code - they'll all just do what they do now if the block device
doesn't support DAX....
-Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
