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[49.181.38.249]) by smtp.gmail.com with ESMTPSA id b4-20020a170902d88400b001d706e373a9sm7935517plz.292.2024.01.30.18.38.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jan 2024 18:38:11 -0800 (PST) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1rV0UL-00HZeK-17; Wed, 31 Jan 2024 13:38:09 +1100 Date: Wed, 31 Jan 2024 13:38:09 +1100 From: Dave Chinner To: Mathieu Desnoyers Cc: Dan Williams , Vishal Verma , Dave Jiang , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds , linux-mm@kvack.org, linux-arch@vger.kernel.org, Matthew Wilcox , Arnd Bergmann , Russell King , nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH v2 1/8] dax: Introduce dax_is_supported() Message-ID: References: <20240130165255.212591-1-mathieu.desnoyers@efficios.com> <20240130165255.212591-2-mathieu.desnoyers@efficios.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240130165255.212591-2-mathieu.desnoyers@efficios.com> 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 > 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 > --- > 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@fromorbit.com