[RFC PATCH] Btrfs-progs: disable qgroupid 0 for quota_tree

[Miao Xie <miaox@cn.fujitsu.com>]

From: Wang Shilong <wangsl-fnst@cn.fujitsu.com>

In kernel, qgroupid 0 is a special number when we run the quota group limit command.

So, we should not be able to create a quota group whose id is 0, otherwise the kernel
can't deal with it. Fix it.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
 cmds-qgroup.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/cmds-qgroup.c b/cmds-qgroup.c
index 70019d0..dfff1b9 100644
--- a/cmds-qgroup.c
+++ b/cmds-qgroup.c
@@ -86,6 +86,10 @@ static int qgroup_create(int create, int argc, char **argv)
 	args.create = create;
 	args.qgroupid = parse_qgroupid(argv[1]);
 
+	if (!args.qgroupid) {
+		fprintf(stderr, "ERROR: qgroup 0 is not supported\n");
+		return 30;
+	}
 	fd = open_file_or_dir(path);
 	if (fd < 0) {
 		fprintf(stderr, "ERROR: can't access '%s'\n", path);
-- 1.7.7.6