xfs/libxfs: replace kmalloc() and memcpy() with kmemdup()

The source static analysis tool gave the following advice:

./fs/xfs/libxfs/xfs_dir2.c:382:15-22: WARNING opportunity for kmemdup

 → 382         args->value = kmalloc(len,
   383                          GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
   384         if (!args->value)
   385                 return -ENOMEM;
   386
 → 387         memcpy(args->value, name, len);
   388         args->valuelen = len;
   389         return -EEXIST;

Replacing kmalloc() + memcpy() with kmemdump() doesn't change semantics.
Original code works without fault, so this is not a bug fix but proposed improvement.

Link: https://lwn.net/Articles/198928/
Fixes: 94a69db ("xfs: use __GFP_NOLOCKDEP instead of GFP_NOFS")
Fixes: 384f3ce ("[XFS] Return case-insensitive match for dentry cache")
Fixes: 2451337 ("xfs: global error sign conversion")
Cc: Carlos Maiolino <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Reviewed-by: "Darrick J. Wong" <[email protected]>
Signed-off-by: Mirsad Todorovac <[email protected]>
Signed-off-by: Carlos Maiolino <[email protected]>

Author: Mirsad Todorovac

fs/xfs/libxfs/xfs_dir2.c

@@ -379,12 +379,11 @@ xfs_dir_cilookup_result(
 					!(args->op_flags & XFS_DA_OP_CILOOKUP))
 		return -EEXIST;
 
-	args->value = kmalloc(len,
+	args->value = kmemdup(name, len,
 			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
 	if (!args->value)
 		return -ENOMEM;
 
-	memcpy(args->value, name, len);
 	args->valuelen = len;
 	return -EEXIST;
 }