config: remove HAVE_BIO_SET_DEV

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes openzfs#16479

config/kernel-bio.m4

@@ -66,28 +66,20 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_SET_DEV_MACRO], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_BIO_SET_DEV], [
-	AC_MSG_CHECKING([whether bio_set_dev() is available])
-	ZFS_LINUX_TEST_RESULT([bio_set_dev], [
+	AC_MSG_CHECKING([whether bio_set_dev() is GPL-only])
+	ZFS_LINUX_TEST_RESULT([bio_set_dev_license], [
+		AC_MSG_RESULT(no)
+	],[
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_BIO_SET_DEV, 1, [bio_set_dev() is available])
-
-		AC_MSG_CHECKING([whether bio_set_dev() is GPL-only])
-		ZFS_LINUX_TEST_RESULT([bio_set_dev_license], [
-			AC_MSG_RESULT(no)
-		],[
-			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_BIO_SET_DEV_GPL_ONLY, 1,
-			    [bio_set_dev() GPL-only])
-		])
+		AC_DEFINE(HAVE_BIO_SET_DEV_GPL_ONLY, 1,
+		    [bio_set_dev() GPL-only])
+	])
 
-		AC_MSG_CHECKING([whether bio_set_dev() is a macro])
-		ZFS_LINUX_TEST_RESULT([bio_set_dev_macro], [
-			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_BIO_SET_DEV_MACRO, 1,
-			    [bio_set_dev() is a macro])
-		],[
-			AC_MSG_RESULT(no)
-		])
+	AC_MSG_CHECKING([whether bio_set_dev() is a macro])
+	ZFS_LINUX_TEST_RESULT([bio_set_dev_macro], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BIO_SET_DEV_MACRO, 1,
+		    [bio_set_dev() is a macro])
 	],[
 		AC_MSG_RESULT(no)
 	])

module/os/linux/zfs/vdev_disk.c

@@ -493,7 +493,6 @@ vdev_disk_close(vdev_t *v)
  */
 #if !defined(HAVE_BIO_ALLOC_4ARG)
 
-#ifdef HAVE_BIO_SET_DEV
 #if defined(CONFIG_BLK_CGROUP) && defined(HAVE_BIO_SET_DEV_GPL_ONLY)
 /*
  * The Linux 5.5 kernel updated percpu_ref_tryget() which is inlined by
@@ -579,16 +578,6 @@ vdev_bio_set_dev(struct bio *bio, struct block_device *bdev)
 #define	bio_set_dev		vdev_bio_set_dev
 #endif
 #endif
-#else
-/*
- * Provide a bio_set_dev() helper macro for pre-Linux 4.14 kernels.
- */
-static inline void
-bio_set_dev(struct bio *bio, struct block_device *bdev)
-{
-	bio->bi_bdev = bdev;
-}
-#endif /* HAVE_BIO_SET_DEV */
 #endif /* !HAVE_BIO_ALLOC_4ARG */
 
 static inline void