X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=dss.c;h=b09fc961f28328eb9c7c6e95726fffa3b706de32;hb=e3f9c1dcc861be14fc9a3f33057a905047e9a926;hp=b6a3d3e714059861ab1ae100933655b7e4e13c50;hpb=dd3f58c0bdf1e9f7bb86d09e6f7faf155d6b5310;p=dss.git

diff --git a/dss.c b/dss.c
index b6a3d3e..b09fc96 100644
--- a/dss.c
+++ b/dss.c
@@ -81,7 +81,7 @@ static int64_t next_snapshot_time;
 static struct timeval next_removal_check;
 /** Creation time of the snapshot currently being created. */
 static int64_t current_snapshot_creation_time;
-/** The snapshot currently being removed. */
+/* Set by the pre-rm hook, cleared by handle_remove_exit(). */
 struct snapshot *snapshot_currently_being_removed;
 /** Needed by the post-create hook. */
 static char *path_to_last_complete_snapshot;
@@ -574,9 +574,6 @@ static int is_reference_snapshot(struct snapshot *s)
 	return strcmp(s->name, name_of_reference_snapshot)? 0 : 1;
 }
 
-/*
- * return: 0: no redundant snapshots, 1: rm process started, negative: error
- */
 static struct snapshot *find_redundant_snapshot(struct snapshot_list *sl)
 {
 	int i, interval;
@@ -654,6 +651,7 @@ static struct snapshot *find_oldest_removable_snapshot(struct snapshot_list *sl)
 	int i, num_complete;
 	struct snapshot *s, *ref = NULL;
 
+	DSS_DEBUG_LOG(("picking snapshot with earliest creation time\n"));
 	num_complete = num_complete_snapshots(sl);
 	if (num_complete <= OPT_UINT32_VAL(DSS, MIN_COMPLETE))
 		return NULL;
@@ -664,7 +662,6 @@ static struct snapshot *find_oldest_removable_snapshot(struct snapshot_list *sl)
 			ref = s;
 			continue;
 		}
-		DSS_INFO_LOG(("oldest removable snapshot: %s\n", s->name));
 		return s;
 	}
 	assert(ref);
@@ -672,6 +669,50 @@ static struct snapshot *find_oldest_removable_snapshot(struct snapshot_list *sl)
 	return ref;
 }
 
+/* returns NULL <==> *reason is set to NULL */
+static struct snapshot *find_removable_snapshot(struct snapshot_list *sl,
+		bool try_hard, char **reason)
+{
+	struct snapshot *victim;
+
+	/*
+	 * Don't remove anything if there is free space and we have fewer
+	 * snapshots than configured, plus one. This way there is always one
+	 * snapshot that can be recycled.
+	 */
+	if (!try_hard && sl->num_snapshots <=
+			1 << OPT_UINT32_VAL(DSS, NUM_INTERVALS))
+		goto nope;
+	victim = find_orphaned_snapshot(sl);
+	if (victim) {
+		*reason = make_message("orphaned");
+		return victim;
+	}
+	victim = find_outdated_snapshot(sl);
+	if (victim) {
+		*reason = make_message("outdated");
+		return victim;
+	}
+	if (!OPT_GIVEN(DSS, KEEP_REDUNDANT)) {
+		victim = find_redundant_snapshot(sl);
+		if (victim) {
+			*reason = make_message("redundant");
+			return victim;
+		}
+	}
+	if (!try_hard)
+		goto nope;
+	DSS_WARNING_LOG(("nothing obvious to remove\n"));
+	victim = find_oldest_removable_snapshot(sl);
+	if (victim) {
+		*reason = make_message("oldest");
+		return victim;
+	}
+nope:
+	*reason = NULL;
+	return NULL;
+}
+
 static int rename_incomplete_snapshot(int64_t start)
 {
 	char *old_name;
@@ -704,7 +745,7 @@ static int try_to_free_disk_space(void)
 	struct snapshot_list sl;
 	struct snapshot *victim;
 	struct timeval now;
-	const char *why;
+	char *why;
 	int low_disk_space;
 
 	ret = disk_space_low(NULL);
@@ -715,55 +756,25 @@ static int try_to_free_disk_space(void)
 	if (tv_diff(&next_removal_check, &now, NULL) > 0)
 		return 0;
 	if (!low_disk_space) {
-		if (OPT_GIVEN(DSS, KEEP_REDUNDANT))
-			return 0;
 		if (snapshot_creation_status != HS_READY)
 			return 0;
 		if (next_snapshot_is_due())
 			return 0;
 	}
-	/*
-	 * Idle and --keep_redundant not given, or low disk space. Look at
-	 * existing snapshots.
-	 */
+	/* Idle or low disk space, look at existing snapshots. */
 	dss_get_snapshot_list(&sl);
-	ret = 0;
-	/*
-	 * Don't remove anything if there is free space and we have fewer
-	 * snapshots than configured, plus one. This way there is always one
-	 * snapshot that can be recycled.
-	 */
-	if (!low_disk_space && sl.num_snapshots <=
-			1 << OPT_UINT32_VAL(DSS, NUM_INTERVALS))
-		goto out;
-	why = "outdated";
-	victim = find_outdated_snapshot(&sl);
-	if (victim)
-		goto remove;
-	why = "redundant";
-	victim = find_redundant_snapshot(&sl);
-	if (victim)
-		goto remove;
-	why = "orphaned";
-	victim = find_orphaned_snapshot(&sl);
+	victim = find_removable_snapshot(&sl, low_disk_space, &why);
+	if (victim) {
+		pre_remove_hook(victim, why);
+		free(why);
+	}
+	free_snapshot_list(&sl);
 	if (victim)
-		goto remove;
-	/* try harder only if disk space is low */
+		return 1;
 	if (!low_disk_space)
-		goto out;
-	DSS_WARNING_LOG(("disk space low and nothing obvious to remove\n"));
-	why = "oldest";
-	victim = find_oldest_removable_snapshot(&sl);
-	if (victim)
-		goto remove;
+		return 0;
 	DSS_CRIT_LOG(("uhuhu: disk space low and nothing to remove\n"));
-	ret = -ERRNO_TO_DSS_ERROR(ENOSPC);
-	goto out;
-remove:
-	pre_remove_hook(victim, why);
-out:
-	free_snapshot_list(&sl);
-	return ret;
+	return -ERRNO_TO_DSS_ERROR(ENOSPC);
 }
 
 static void post_create_hook(void)
@@ -1664,6 +1675,7 @@ static int com_prune(void)
 	victim = find_redundant_snapshot(&sl);
 	if (victim)
 		goto rm;
+	dss_msg("nothing to prune\n");
 	ret = 0;
 	goto out;
 rm:
@@ -1678,6 +1690,7 @@ rm:
 		ret = wait_for_remove_process();
 		if (ret < 0)
 			goto out;
+		ret = -E_HOOK_FAILED;
 		if (snapshot_removal_status != HS_PRE_SUCCESS)
 			goto out;
 	}
@@ -1687,11 +1700,9 @@ rm:
 	ret = wait_for_remove_process();
 	if (ret < 0)
 		goto out;
-	if (snapshot_removal_status != HS_SUCCESS)
-		goto out;
+	assert(snapshot_removal_status == HS_SUCCESS);
 	post_remove_hook();
-	if (snapshot_removal_status != HS_POST_RUNNING)
-		goto out;
+	assert(snapshot_removal_status == HS_POST_RUNNING);
 	ret = wait_for_remove_process();
 	if (ret < 0)
 		goto out;