[sheepdog] [PATCH] dog: allow vdi snapshot without snapshot tag

[Hitoshi Mitake]

The commit a21bf27906b23448b92cca9943e1019105ffac2f makes
$ dog vdi snapshot <vdi>
fail if the <vdi> is an ordinal vdi because newly created VDIs have
snapid 0. This patch avoids the failure with checking the VDI is
snapshot or not.

Cc: Ruoyu <liangry at ucweb.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
 dog/vdi.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/dog/vdi.c b/dog/vdi.c
index fa6130e..0a8a2e9 100644
--- a/dog/vdi.c
+++ b/dog/vdi.c
@@ -567,6 +567,7 @@ static int vdi_snapshot(int argc, char **argv)
 	int vs_count = 0;
 	struct node_id owners[SD_MAX_COPIES];
 	int nr_owners = 0, nr_issued_prevent_inode_update = 0;
+	bool fail_if_snapshot = false;
 
 	if (vdi_cmd_data.snapshot_id != 0) {
 		sd_err("Please specify a non-integer value for "
@@ -584,6 +585,15 @@ static int vdi_snapshot(int argc, char **argv)
 	case SD_RES_NO_TAG:
 		break;
 	default:
+		fail_if_snapshot = true;
+		break;
+	}
+
+	ret = read_vdi_obj(vdiname, 0, "", &vid, inode, SD_INODE_HEADER_SIZE);
+	if (ret != EXIT_SUCCESS)
+		return ret;
+
+	if (fail_if_snapshot && vdi_is_snapshot(inode)) {
 		sd_err("Failed to create snapshot for %s, maybe "
 			"snapshot id (%d) or tag (%s) is existed",
 			vdiname, vdi_cmd_data.snapshot_id,
@@ -591,10 +601,6 @@ static int vdi_snapshot(int argc, char **argv)
 		return EXIT_FAILURE;
 	}
 
-	ret = read_vdi_obj(vdiname, 0, "", &vid, inode, SD_INODE_HEADER_SIZE);
-	if (ret != EXIT_SUCCESS)
-		return ret;
-
 	if (inode->store_policy) {
 		sd_err("creating a snapshot of hypervolume is not supported");
 		return EXIT_FAILURE;
-- 
1.8.3.2