document new lxc-create btrfs behavior

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/doc/lxc-create.sgml.in b/doc/lxc-create.sgml.in
index f9b0228ec3c0be0499ff631546e49a67f7e92523..a8de5b5b6729ae8e4622ecefc61a8ff1771030e3 100644 (file)
--- a/doc/lxc-create.sgml.in
+++ b/doc/lxc-create.sgml.in
@@ -131,10 +131,12 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
            'dir' has the same meaning as 'none', but also allows the optional
            <replaceable>--dir ROOTFS</replaceable> to be specified, meaning
            that the container rootfs should be placed under the specified path,
-           rather than the default.
-           The option 'btrfs' need not be specified as it will be used
-           automatically if the <filename>@LXCPATH@</filename> filesystem is found to
-           be btrfs.  If backingstore is 'lvm', then an lvm block device will be
+           rather than the default.  If 'btrfs' is specified, then the
+           target filesystem must be btrfs, and the container rootfs will be
+           created as a new subvolume.  This allows snapshotted clones to be
+           created, but also causes rsync --one-filesystem to treat it as a
+           separate filesystem.
+           If backingstore is 'lvm', then an lvm block device will be
            used and the following further options are available:
            <replaceable>--lvname lvname1</replaceable> will create an LV
            named <filename>lvname1</filename> rather than the default, which