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IOzbNY0DCaxdX0gkGlA4G6E37Bn7F74Z8DlhfE3DZfoWO4nA7cf+yC3fcop48rZ44xAgxUo7HZhRV6v1e+2iNKRylXwHy93GK1MbmWQN7NMALu+dF/mz88F2v+XUdJImD09YM4BoYRa3np+bxQhoxuh+Dcg3VKshVmI0H9W7NbGmcdKl7lpYd0Fmlr7QQW0GBPu/WfZTbGAWdrOgyZYMV2Xv9eUFNjzcC686mClTruotv9B7qcRRFeC/8Z48KoIsTIKP1d9gxUOFPPFxeKw9etE233KKlLY3HpGBBRlH5765mH0Weh4xKn1xo3PBjDaiSTs3RmKxm3Xdt4ZY/Qm1Ey5XimAwn4JnBMdREQYJ2Ek5cm//1lKXmjKYU9yA/ns340qUfyXnt+JZLeC7uRQo+/p2+REX8AYdbdrngeuqFDCYEAxn2NpW6+Cu6s9xHrESLo1Wgj2KEzMcUkXzNCx1RylugVP+Na4WoBp9jvjlTEF2u6ska0YJNaEYsQsCfHC+WyLUyjiP5jJbKMZHKblNSAvlyQATK2B1ojM8BVADq9rq4rJCII6cdLSLCiCvoCJqQO/fzACzZ5kxPBZLTK/jFRq2ZK0aXoZr8wIbvlQ0ysWgjKxY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Mathieu Desnoyers wrote: > Replace the following fs/Kconfig:FS_DAX dependency: > > depends on !(ARM || MIPS || SPARC) > > By a runtime check within alloc_dax(). > > 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 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 > Cc: Andrew Morton > Cc: Linus Torvalds > Cc: linux-mm@kvack.org > Cc: linux-arch@vger.kernel.org > Cc: Dan Williams > Cc: Vishal Verma > Cc: Dave Jiang > Cc: Matthew Wilcox > Cc: Arnd Bergmann > Cc: Russell King > Cc: nvdimm@lists.linux.dev > Cc: linux-cxl@vger.kernel.org > Cc: linux-fsdevel@vger.kernel.org > Cc: dm-devel@lists.linux.dev > --- > drivers/dax/super.c | 6 ++++++ > fs/Kconfig | 1 - > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 0da9232ea175..e9f397b8a5a3 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -445,6 +445,12 @@ 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. */ > + if (IS_ENABLED(CONFIG_ARM) || > + IS_ENABLED(CONFIG_MIPS) || > + IS_ENABLED(CONFIG_SPARC)) > + return NULL; This function returns ERR_PTR(), not NULL on failure. ...and I notice this mistake is also made in include/linux/dax.h in the CONFIG_DAX=n case. That function also mentions: static inline struct dax_device *alloc_dax(void *private, const struct dax_operations *ops) { /* * Callers should check IS_ENABLED(CONFIG_DAX) to know if this * NULL is an error or expected. */ return NULL; } ...and none of the callers validate the result, but now runtime validation is necessary. I.e. it is not enough to check IS_ENABLED(CONFIG_DAX) it also needs to check cpu_dcache_is_aliasing(). With that, there are a few more fixup places needed, pmem_attach_disk(), dcssblk_add_store(), and virtio_fs_setup_dax().