Add -u option to 'zfs create'

Add -u option to 'zfs create' that prevents file system from being
automatically mounted. This is similar to the 'zfs receive -u'.

Authored by: pjd <pjd@FreeBSD.org>
FreeBSD-commit: freebsd/freebsd@35c58230e2

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Ported-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #11254

man/man8/zfs-create.8

@@ -30,7 +30,7 @@
 .\" Copyright 2018 Nexenta Systems, Inc.
 .\" Copyright 2019 Joyent, Inc.
 .\"
-.Dd June 30, 2019
+.Dd December 1, 2020
 .Dt ZFS-CREATE 8
 .Os
 .Sh NAME
@@ -39,7 +39,7 @@
 .Sh SYNOPSIS
 .Nm zfs
 .Cm create
-.Op Fl Pnpv
+.Op Fl Pnpuv
 .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ...
 .Ar filesystem
 .Nm zfs
@@ -53,14 +53,16 @@
 .It Xo
 .Nm zfs
 .Cm create
-.Op Fl Pnpv
+.Op Fl Pnpuv
 .Oo Fl o Ar property Ns = Ns Ar value Oc Ns ...
 .Ar filesystem
 .Xc
 Creates a new ZFS file system.
 The file system is automatically mounted according to the
 .Sy mountpoint
-property inherited from the parent.
+property inherited from the parent, unless the
+.Fl u
+option is used.
 .Bl -tag -width "-o"
 .It Fl o Ar property Ns = Ns Ar value
 Sets the specified property as if the command
@@ -122,6 +124,8 @@ to
 due to the use of the
 .Fl o
 option.
+.It Fl u
+Do not mount the newly created file system.
 .It Fl v
 Print verbose information about the created dataset.
 .El