makefs: Remove the warning printed when makefs -t zfs is used

We haven't seen bug reports relating to this feature for a while, so
stop printing a warning.

Reviewed by:	cperciva
MFC after:	2 weeks

(cherry picked from commit d9fe71828797508d1d28655e40780a5ae9078e66)

usr.sbin/makefs/tests/makefs_zfs_tests.sh

@@ -28,7 +28,7 @@
 # SUCH DAMAGE.
 #
 
-MAKEFS="makefs -t zfs -o verify-txgs=true -o nowarn=true"
+MAKEFS="makefs -t zfs -o verify-txgs=true"
 ZFS_POOL_NAME="makefstest$$"
 TEST_ZFS_POOL_NAME="$TMPDIR/poolname"
 

usr.sbin/makefs/zfs.c

@@ -94,7 +94,7 @@ zfs_prep_opts(fsinfo_t *fsopts)
 		{ '\0', "verify-txgs", &zfs->verify_txgs, OPT_BOOL,
 		  0, 0, "Make OpenZFS verify data upon import" },
 		{ '\0', "nowarn", &zfs->nowarn, OPT_BOOL,
-		  0, 0, "Suppress warning about experimental ZFS support" },
+		  0, 0, "Provided for backwards compatibility, ignored" },
 		{ .name = NULL }
 	};
 
@@ -792,12 +792,6 @@ zfs_makefs(const char *image, const char *dir, fsnode *root, fsinfo_t *fsopts)
 
 	zfs_check_opts(fsopts);
 
-	if (!zfs->nowarn) {
-		fprintf(stderr,
-		    "ZFS support is currently considered experimental. "
-		    "Do not use it for anything critical.\n");
-	}
-
 	dirfd = open(dir, O_DIRECTORY | O_RDONLY);
 	if (dirfd < 0)
 		err(1, "open(%s)", dir);

usr.sbin/makefs/zfs/zfs.h

@@ -74,7 +74,7 @@ typedef struct {
 	 */
 	char		filebuf[MAXBLOCKSIZE] __aligned(alignof(uint64_t));
 
-	bool		nowarn;
+	bool		nowarn;		/* ignored */
 
 	/* Pool parameters. */
 	const char	*poolname;