From: Andre Noll <maan@tuebingen.mpg.de>
Date: Fri, 12 Dec 2014 13:21:53 +0000 (+0100)
Subject: Merge branch 'refs/heads/t/min-complete'
X-Git-Tag: v0.1.6~16
X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=commitdiff_plain;h=15eb99dcf9a30f8c8d488d5bc3c92130cf828d60;hp=7e93c92b8896690059fff7d6b56ba149ca182294

Merge branch 'refs/heads/t/min-complete'
---

diff --git a/dss.c b/dss.c
index 0ad7a35..006cd27 100644
--- a/dss.c
+++ b/dss.c
@@ -531,17 +531,25 @@ static struct snapshot *find_outdated_snapshot(struct snapshot_list *sl)
 
 static struct snapshot *find_oldest_removable_snapshot(struct snapshot_list *sl)
 {
-	int i;
-	struct snapshot *s;
+	int i, num_complete;
+	struct snapshot *s, *ref = NULL;
+
+	num_complete = num_complete_snapshots(sl);
+	if (num_complete <= conf.min_complete_arg)
+		return NULL;
 	FOR_EACH_SNAPSHOT(s, i, sl) {
 		if (snapshot_is_being_created(s))
 			continue;
-		if (is_reference_snapshot(s))
+		if (is_reference_snapshot(s)) { /* avoid this one */
+			ref = s;
 			continue;
+		}
 		DSS_INFO_LOG(("oldest removable snapshot: %s\n", s->name));
 		return s;
 	}
-	return NULL;
+	assert(ref);
+	DSS_WARNING_LOG(("removing reference snapshot %s\n", ref->name));
+	return ref;
 }
 
 static int rename_incomplete_snapshot(int64_t start)
diff --git a/dss.ggo b/dss.ggo
index ac7f5b7..9587dd2 100644
--- a/dss.ggo
+++ b/dss.ggo
@@ -439,3 +439,23 @@ details="
 	becomes low. Use this flag if the file system containing the
 	destination directory is used for snapshots only.
 "
+
+option "min-complete" -
+#~~~~~~~~~~~~~~~~~~~~~~
+"Minimal number of complete snapshots to keep"
+int typestr = "num"
+default = "1"
+optional
+details = "
+	This option is only relevant if snapshots must be deleted
+	because disk space gets low.
+
+	dss refuses to remove old snapshots if there are fewer complete
+	snapshots left than the given number. The default value of one
+	guarantees that at least one complete snapshot is available
+	at all times.
+
+	If only <num> complete snapshot are left, and there is not
+	enough disk space available for another snapshot, the program
+	terminates with a \"No space left on device\" error.
+"
diff --git a/snap.c b/snap.c
index 4dbb446..7c16d2e 100644
--- a/snap.c
+++ b/snap.c
@@ -232,3 +232,13 @@ __malloc char *name_of_newest_complete_snapshot(struct snapshot_list *sl)
 	return name;
 }
 
+int num_complete_snapshots(struct snapshot_list *sl)
+{
+	struct snapshot *s;
+	int i, ret = 0;
+
+	FOR_EACH_SNAPSHOT(s, i, sl)
+		if (s->flags & SS_COMPLETE)
+			ret++;
+	return ret;
+}
diff --git a/snap.h b/snap.h
index 8fee138..626ecad 100644
--- a/snap.h
+++ b/snap.h
@@ -88,6 +88,7 @@ __malloc char *incomplete_name(int64_t start);
 __malloc char *being_deleted_name(struct snapshot *s);
 int complete_name(int64_t start, int64_t end, char **result);
 __malloc char *name_of_newest_complete_snapshot(struct snapshot_list *sl);
+int num_complete_snapshots(struct snapshot_list *sl);
 
 /**
  * Get the newest snapshot in a snapshot list.