@@ -56,7 +56,7 @@ endif # BLOCK
config FS_DAX
bool "File system based Direct Access (DAX) support"
depends on MMU
- depends on !(ARM || MIPS || SPARC)
+ depends on !ARCH_HAS_CACHE_ALIASING
depends on ZONE_DEVICE || FS_DAX_LIMITED
select FS_IOMAP
select DAX
@@ -5,6 +5,7 @@
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/radix-tree.h>
+#include <linux/cacheinfo.h>
typedef unsigned long dax_entry_t;
@@ -78,6 +79,10 @@ 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 !cache_is_aliasing();
+}
#else
static inline void *dax_holder(struct dax_device *dax_dev)
{
@@ -122,6 +127,10 @@ static inline size_t dax_recovery_write(struct dax_device *dax_dev,
{
return 0;
}
+static inline bool dax_is_supported(void)
+{
+ return false;
+}
#endif
void set_dax_nocache(struct dax_device *dax_dev);
fs/Kconfig:FS_DAX prevents DAX from building on architectures with virtually aliased dcache with: depends on !(ARM || MIPS || SPARC) This check is too broad (e.g. recent ARMv7 don't have virtually aliased dcaches), and also misses many other architectures with virtually aliased dcache. This is a regression introduced in the v5.13 Linux kernel where the dax mount option is removed for 32-bit ARMv7 boards which have no dcache aliasing, and therefore should work fine with FS_DAX. Use this instead in Kconfig to prevent FS_DAX from being built on architectures with virtually aliased dcache: depends on !ARCH_HAS_CACHE_ALIASING For architectures which detect dcache aliasing at runtime, introduce a new dax_is_supported() static inline which uses "cache_is_aliasing()" to figure out whether the environment has aliasing dcaches. This new dax_is_supported() helper will be used in each filesystem supporting the dax mount option to validate whether dax is indeed supported. Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-mm@kvack.org Cc: linux-arch@vger.kernel.org Cc: Dan Williams <dan.j.williams@intel.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: nvdimm@lists.linux.dev Cc: linux-cxl@vger.kernel.org --- fs/Kconfig | 2 +- include/linux/dax.h | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-)