Allow the user to not specify a size when creating snapshot.

For shared snapshot, the size is not required. If the user creates other
volume than a shared snapshot, zero size will be rejected in lv_create_single.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 tools/lvcreate.c |    4 ++++
 1 file changed, 4 insertions(+)

Index: LVM2.2.02.84/tools/lvcreate.c
===================================================================
--- LVM2.2.02.84.orig/tools/lvcreate.c	2011-05-05 02:11:49.000000000 +0200
+++ LVM2.2.02.84/tools/lvcreate.c	2011-05-05 02:11:59.000000000 +0200
@@ -195,6 +195,9 @@ static int _read_size_params(struct lvcr
 			     struct lvcreate_cmdline_params *lcp,
 			     struct cmd_context *cmd)
 {
+	if (!arg_count(cmd, extents_ARG) && !arg_count(cmd, size_ARG))
+		goto skip_size_arg;
+
 	if (arg_count(cmd, extents_ARG) + arg_count(cmd, size_ARG) != 1) {
 		log_error("Please specify either size or extents (not both)");
 		return 0;
@@ -219,6 +222,7 @@ static int _read_size_params(struct lvcr
 		lcp->percent = PERCENT_NONE;
 	}
 
+skip_size_arg:
 	/* Size returned in kilobyte units; held in sectors */
 	if (arg_count(cmd, virtualsize_ARG)) {
 		if (arg_sign_value(cmd, virtualsize_ARG, 0) == SIGN_MINUS) {