On 02/13/2018 01:31 PM, Ross Zwisler wrote:

On Thu, Feb 08, 2018 at 05:38:19PM -0700, Dave Jiang wrote:

quoted

The function return values are confusing with the way the function is
named. We expect a true or false return value but it actually returns
0/-errno.  This makes the code very confusing. Changing the return values
to return a bool where if DAX is supported then return true and no DAX
support returns false.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---

quoted

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 655699321c45..636b9c5e1bff 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c

@@ -958,9 +958,10 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 
 	if (sbi->s_mount_opt & EXT2_MOUNT_DAX) {
-		err = sb_dax_supported(sb, blocksize);
-		if (err)
+		if(!sb_dax_supported(sb, blocksize)) {
+			err = -EIO;

No need to set 'err' here.  This is just a temporary variable used for some
local checks later in the function.  'ret' is the value that will be returned,
and that is already initialized to -EINVAL which should be fine.

Change ret to -EIO instead to set the correct error return code?

quoted

 			goto failed_mount;
+		}
 	}
 
 	/* If the blocksize doesn't match, re-read the thing.. */

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 804a2d6729af..7b7650ac9c53 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c

@@ -3712,9 +3712,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 					" that may contain inline data");
 			goto failed_mount;
 		}
-		err = sb_dax_supported(sb, blocksize);
-		if (err)
+		if (!sb_dax_supported(sb, blocksize)) {
+			err = -EIO;

Same comment as with the ext2 case - no need to set 'err', 'ret' is -EINVAL
and has you covered.