From: Andre Noll <maan@systemlinux.org>
Date: Tue, 7 Apr 2009 14:17:01 +0000 (+0200)
Subject: Merge branch 'master' into rm_hook
X-Git-Tag: v0.1.3~15
X-Git-Url: http://git.tuebingen.mpg.de/?p=dss.git;a=commitdiff_plain;h=0ca40f54698dc00d81e40f784e27628f8fe802c0;hp=d98f153760260186e7350c5ac51c3e60410166ef

Merge branch 'master' into rm_hook
---

diff --git a/dss.c b/dss.c
index 3bfcfe7..6dbe11f 100644
--- a/dss.c
+++ b/dss.c
@@ -44,8 +44,8 @@ static int signal_pipe;
 static pid_t create_pid;
 /** Whether the pre-create-hook/rsync/post-create-hook is currently stopped. */
 static int create_process_stopped;
-/** Process id of current rm process. */
-static pid_t rm_pid;
+/** Process id of current pre-remove/rm/post-remove process. */
+static pid_t remove_pid;
 /** When the next snapshot is due. */
 static struct timeval next_snapshot_time;
 /** Creation time of the snapshot currently being created. */
@@ -54,6 +54,8 @@ static int64_t current_snapshot_creation_time;
 static char *path_to_last_complete_snapshot;
 /** \sa \ref snap.h for details. */
 static unsigned snapshot_creation_status;
+/** \sa \ref snap.h for details. */
+static unsigned snapshot_removal_status;
 
 
 DEFINE_DSS_ERRLIST;
@@ -191,7 +193,7 @@ out:
 static int remove_snapshot(struct snapshot *s, char *why)
 {
 	int fds[3] = {0, 0, 0};
-	assert(!rm_pid);
+	assert(!remove_pid);
 	char *new_name = being_deleted_name(s);
 	int ret = dss_rename(s->name, new_name);
 	char *argv[] = {"rm", "-rf", new_name, NULL};
@@ -200,7 +202,7 @@ static int remove_snapshot(struct snapshot *s, char *why)
 		goto out;
 	DSS_NOTICE_LOG("removing %s snapshot %s (interval = %i)\n",
 		why, s->name, s->interval);
-	ret = dss_exec(&rm_pid, argv[0], argv, fds);
+	ret = dss_exec(&remove_pid, argv[0], argv, fds);
 out:
 	free(new_name);
 	return ret;
@@ -474,7 +476,7 @@ static int wait_for_process(pid_t pid, int *status)
 
 static int handle_rm_exit(int status)
 {
-	rm_pid = 0;
+	remove_pid = 0;
 	if (!WIFEXITED(status))
 		return -E_INVOLUNTARY_EXIT;
 	if (WEXITSTATUS(status))
@@ -484,7 +486,7 @@ static int handle_rm_exit(int status)
 
 static int wait_for_rm_process(void)
 {
-	int status, ret = wait_for_process(rm_pid, &status);
+	int status, ret = wait_for_process(remove_pid, &status);
 
 	if (ret < 0)
 		return ret;
@@ -585,7 +587,7 @@ static int handle_sigchld(void)
 			return -E_BUG;
 		}
 	}
-	if (pid == rm_pid)
+	if (pid == remove_pid)
 		return handle_rm_exit(status);
 	DSS_EMERG_LOG("BUG: unknown process %d died\n", (int)pid);
 	return -E_BUG;
@@ -709,7 +711,7 @@ static int handle_signal(void)
 	case SIGTERM:
 		restart_create_process();
 		kill_process(create_pid);
-		kill_process(rm_pid);
+		kill_process(remove_pid);
 		ret = -E_SIGNAL;
 		break;
 	case SIGHUP:
@@ -815,7 +817,7 @@ static int select_loop(void)
 		int low_disk_space;
 		struct timeval now, *tvp;
 
-		if (rm_pid)
+		if (remove_pid)
 			tvp = NULL; /* sleep until rm process dies */
 		else { /* sleep one minute */
 			tv.tv_sec = 60;
@@ -833,7 +835,7 @@ static int select_loop(void)
 			if (ret < 0)
 				goto out;
 		}
-		if (rm_pid)
+		if (remove_pid)
 			continue;
 		ret = disk_space_low();
 		if (ret < 0)
@@ -842,7 +844,7 @@ static int select_loop(void)
 		ret = try_to_free_disk_space(low_disk_space);
 		if (ret < 0)
 			goto out;
-		if (rm_pid) {
+		if (remove_pid) {
 			stop_create_process();
 			continue;
 		}
diff --git a/dss.ggo b/dss.ggo
index 099df4c..9c687f4 100644
--- a/dss.ggo
+++ b/dss.ggo
@@ -277,6 +277,37 @@ details="
 	store them in a database for further analysis.
 "
 
+option "pre-remove-hook" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Executed before snapshot removal"
+string typestr="command"
+optional
+details="
+	Execute this command before removing a snapshot. If this
+	command returns with a non-zero exit status, no snapshot is
+	being removed and the operation is retried later.
+
+	For example, one might want to execute a script that checks
+	whether the snapshot to be deleted is currently used by
+	another process, e.g. by a tape-based backup system that runs
+	concurrently to dss.
+
+	Another possible application of this is to record disk-usage
+	patterns before and after snapshot removal.
+"
+
+option "post-remove-hook" -
+#~~~~~~~~~~~~~~~~~~~~~~~~~~
+"Executed after snapshot removal"
+string typestr="command"
+optional
+details="
+	Execute this after a snapshot has successfully been
+	removed. The full path of the removed snapshot is
+	passed to the hook as the first argument. The exit code of
+	this hook is ignored.
+"
+
 option "exit-hook" e
 #~~~~~~~~~~~~~~~~~~~
 "Executed if run command exits"
diff --git a/snap.h b/snap.h
index afac5e9..7ac951f 100644
--- a/snap.h
+++ b/snap.h
@@ -22,6 +22,20 @@ enum {
 	SCS_POST_HOOK_RUNNING,
 };
 
+/** The state of snapshot removal. */
+enum {
+	/** No snapshot is currently being removed. */
+	SRS_READY,
+	/** The pre-removal hook has been started. */
+	SRS_PRE_HOOK_RUNNING,
+	/** The pre-remove hook failed, we're waiting to execute it again. */
+	SRS_PRE_HOOK_FAILURE,
+	/** The rm command is currently executing. */
+	SRS_RM_RUNNING,
+	/** The post-remove hook ist running. */
+	SRS_POST_HOOK_RUNNING,
+};
+
 /**
  * The status of a snapshot.
  *