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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Dan Williams <dan.j.williams@intel.com>,
	Arnd Bergmann <arnd@arndb.de>, Dave Chinner <david@fromorbit.com>
Cc: linux-kernel@vger.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Matthew Wilcox <willy@infradead.org>,
	Russell King <linux@armlinux.org.uk>,
	nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, dm-devel@lists.linux.dev
Subject: [RFC PATCH v3 2/4] dax: Check for data cache aliasing at runtime
Date: Wed, 31 Jan 2024 11:25:31 -0500	[thread overview]
Message-ID: <20240131162533.247710-3-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20240131162533.247710-1-mathieu.desnoyers@efficios.com>

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 <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: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
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;
+
 	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


  parent reply	other threads:[~2024-01-31 16:25 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-31 16:25 [RFC PATCH v3 0/4] Introduce cpu_dcache_is_aliasing() to fix DAX regression Mathieu Desnoyers
2024-01-31 16:25 ` [RFC PATCH v3 1/4] dm: Treat alloc_dax failure as non-fatal Mathieu Desnoyers
2024-01-31 16:25 ` Mathieu Desnoyers [this message]
2024-01-31 21:02   ` [RFC PATCH v3 2/4] dax: Check for data cache aliasing at runtime Dan Williams
2024-01-31 21:39     ` Mathieu Desnoyers
2024-01-31 22:18       ` Dan Williams
2024-02-01 15:44         ` Mathieu Desnoyers
2024-02-02 14:40           ` Mathieu Desnoyers
2024-02-02 16:32           ` Mathieu Desnoyers
2024-02-02 17:37           ` Dan Williams
2024-02-02 19:29             ` Mathieu Desnoyers
2024-02-02 19:41               ` Dan Williams
2024-02-02 20:02                 ` Mathieu Desnoyers
2024-02-02 20:14                   ` Dan Williams
2024-02-02 20:18                     ` Mathieu Desnoyers
2024-01-31 16:25 ` [RFC PATCH v3 3/4] Introduce cpu_dcache_is_aliasing() across all architectures Mathieu Desnoyers
2024-01-31 17:17   ` Christoph Hellwig
2024-01-31 17:59     ` Mathieu Desnoyers
2024-01-31 20:42       ` Dan Williams
2024-01-31 16:25 ` [RFC PATCH v3 4/4] dax: Fix incorrect list of data cache aliasing architectures Mathieu Desnoyers

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