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 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.
IMHO 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.
This patch does the following change for the above purpose,
- if (!dax_dev && !bdev_dax_supported(bdev, blocksize)) {
+ if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
Fixes: c2affe920b0e ("dax: do not print error message for non-persistent memory block device")
Signed-off-by: Coly Li <colyli@xxxxxxx>
Reviewed-and-Tested-by: Adrian Huang <ahuang12@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
---
Changelog:
v3: add more Reviewed-by from Mike Snitzer and Pankaj Gupta.
v2: add Reviewed-and-Tested-by from Adrian Huang.
v1: initial version.
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
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