Replace the following fs/Kconfig:FS_DAX dependency: depends on !(ARM || MIPS || SPARC)
By a runtime check within alloc_dax(). This runtime check returns ERR_PTR(-EOPNOTSUPP) if the @ops parameter is non-NULL (which means the kernel is using an aliased mapping) on an architecture which has data cache aliasing. Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for CONFIG_DAX=n for consistency. This is done in preparation for using cpu_dcache_is_aliasing() in a following change which will properly support architectures which detect data cache aliasing at runtime. Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches") Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> Reviewed-by: Dan Williams <dan.j.willi...@intel.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Dan Williams <dan.j.willi...@intel.com> Cc: Vishal Verma <vishal.l.ve...@intel.com> Cc: Dave Jiang <dave.ji...@intel.com> Cc: Matthew Wilcox <wi...@infradead.org> Cc: Arnd Bergmann <a...@arndb.de> Cc: Russell King <li...@armlinux.org.uk> Cc: linux-a...@vger.kernel.org Cc: linux-...@vger.kernel.org Cc: linux-fsde...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-...@vger.kernel.org Cc: dm-devel@lists.linux.dev Cc: nvd...@lists.linux.dev --- drivers/dax/super.c | 10 ++++++++++ fs/Kconfig | 1 - 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 205b888d45bf..ce5bffa86bba 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -450,6 +450,16 @@ struct dax_device *alloc_dax(void *private, const struct dax_operations *ops) dev_t devt; int minor; + /* + * Unavailable on architectures with virtually aliased data caches, + * except for device-dax (NULL operations pointer), which does + * not use aliased mappings from the kernel. + */ + if (ops && (IS_ENABLED(CONFIG_ARM) || + IS_ENABLED(CONFIG_MIPS) || + IS_ENABLED(CONFIG_SPARC))) + return ERR_PTR(-EOPNOTSUPP); + if (WARN_ON_ONCE(ops && !ops->zero_page_range)) return ERR_PTR(-EINVAL); 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 -- 2.39.2