[sheepdog] [PATCH 1/4] dog/cluster: bug fix when cluster don't have snapshots

[Ruoyu]

This patch fix the problem as below.

this is the first cluster snapshot I try to save, but I forgot to snapshot
the vdi:

dog cluster snapshot save first cluster_snapshots

Object not found. It may be caused by:
1. The cluster is empty.
2. All VDIs of the cluster don't have snapshots.

and that's right!

Then I take vdi snapshot and save cluster snapshot, then remove vdi snapshots.
Now I try to make the same mistake

dog cluster snapshot save second cluster_snapshots
100.0 % [=====] 4 / 4

There are no vdi snapshots and dog doesn't complain about it!
It did it only the first time.

Reported-by: Valerio Pachera <sirio81 at gmail.com>
Signed-off-by: Ruoyu <liangry at ucweb.com>
---
 dog/cluster.c   | 8 ++++++--
 dog/farm/farm.h | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/dog/cluster.c b/dog/cluster.c
index 7c4856d..e42bc54 100644
--- a/dog/cluster.c
+++ b/dog/cluster.c
@@ -365,6 +365,9 @@ static void fill_object_tree(uint32_t vid, const char *name, const char *tag,
 			return;
 	}
 
+	if (i->name[0] != '\0')
+		opt->nr_snapshot++;
+
 	/* fill vdi object id */
 	object_tree_insert(vdi_oid, i->nr_copies, i->copy_policy);
 
@@ -417,14 +420,15 @@ static int save_snapshot(int argc, char **argv)
 		goto out;
 	}
 
+	opt.nr_snapshot = 0;
 	opt.count = argc - optind;
 	opt.name = argv + optind;
 	if (parse_vdi(fill_object_tree, SD_INODE_SIZE,
 			&opt, false) != SD_RES_SUCCESS)
 		goto out;
 
-	if (object_tree_size() == 0) {
-		sd_err("Object not found. It may be caused by:");
+	if (opt.nr_snapshot == 0) {
+		sd_err("Cannot execute. It may be caused by:");
 		if (opt.count > 0) {
 			sd_err("1. The specified VDIs are not found.");
 			sd_err("2. The specified VDIs don't have snapshots.");
diff --git a/dog/farm/farm.h b/dog/farm/farm.h
index 745aa15..f4ec47f 100644
--- a/dog/farm/farm.h
+++ b/dog/farm/farm.h
@@ -50,6 +50,7 @@ struct snap_log {
 };
 
 struct vdi_option {
+	int nr_snapshot;
 	int count;
 	char **name;
 	void (*func)(struct sd_inode *inode);
-- 
1.8.3.2