From 6180bb446ab624b9ab8bf201ed251ca87f07b413 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Fri, 4 Sep 2020 00:16:25 +0800
Subject: [PATCH] dax: fix detection of dax support for non-persistent memory
block devices
Git-commit: 6180bb446ab624b9ab8bf201ed251ca87f07b413
Patch-mainline: v5.9-rc5
References: bsc#1175995, jsc#SLE-15608
When calling __generic_fsdax_supported(), a dax-unsupported device may
not have dax_dev as NULL, e.g. the dax related code block is not enabled
by Kconfig.
Therefore in __generic_fsdax_supported(), to check whether a device
supports DAX or not, the following order of operations should be
Performed:
- If dax_dev pointer is NULL, it means the device driver explicitly
announce it doesn't support DAX. Then it is OK to directly return
false from __generic_fsdax_supported().
- If dax_dev pointer is NOT NULL, it might be because the driver doesn't
support DAX and not explicitly initialize related data structure. Then
bdev_dax_supported() should be called for further check.
If device driver desn't explicitly set its dax_dev pointer to NULL,
this is not a bug. Calling bdev_dax_supported() makes sure they can be
recognized as dax-unsupported eventually.
Fixes: c2affe920b0e ("dax: do not print error message for non-persistent memory block device")
Cc: Jan Kara <jack@suse.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-and-tested-by: Adrian Huang <ahuang12@lenovo.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/20200903161625.19524-1-colyli@suse.de
---
drivers/dax/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 32642634c1bb..e5767c83ea23 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -100,7 +100,7 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
return false;
}
- if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
+ if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
pr_debug("%s: error: dax unsupported by block device\n",
bdevname(bdev, buf));
return false;
--
2.26.2