From 6180bb446ab624b9ab8bf201ed251ca87f07b413 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Fri, 4 Sep 2020 00:16:25 +0800 Subject: [PATCH] dax: fix detection of dax support for non-persistent memory block devices 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 Cc: Vishal Verma Reviewed-and-tested-by: Adrian Huang Reviewed-by: Ira Weiny Reviewed-by: Mike Snitzer Reviewed-by: Pankaj Gupta Signed-off-by: Coly Li Signed-off-by: Vishal Verma 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; -- 2.20.1