Fix zpool history unbounded memory usage

In original implementation, zpool history will read the whole history
before printing anything, causing memory usage goes unbounded. We fix
this by breaking it into read-print iterations.

Reviewed-by: Tom Caputi <[email protected]>
Reviewed-by: Matt Ahrens <[email protected]>
Reviewed-by: Igor Kozhukhov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Chunwei Chen <[email protected]>
Closes #9516 

1 files changed, 28 insertions, 16 deletions

diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index 7a95add94..6071babfd 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -8518,24 +8518,12 @@ typedef struct hist_cbdata {
 	boolean_t internal;
 } hist_cbdata_t;
 
-/*
- * Print out the command history for a specific pool.
- */
-static int
-get_history_one(zpool_handle_t *zhp, void *data)
+static void
+print_history_records(nvlist_t *nvhis, hist_cbdata_t *cb)
 {
-	nvlist_t *nvhis;
 	nvlist_t **records;
 	uint_t numrecords;
-	int ret, i;
-	hist_cbdata_t *cb = (hist_cbdata_t *)data;
-
-	cb->first = B_FALSE;
-
-	(void) printf(gettext("History for '%s':\n"), zpool_get_name(zhp));
-
-	if ((ret = zpool_get_history(zhp, &nvhis)) != 0)
-		return (ret);
+	int i;
 
 	verify(nvlist_lookup_nvlist_array(nvhis, ZPOOL_HIST_RECORD,
 	    &records, &numrecords) == 0);
@@ -8639,8 +8627,32 @@ get_history_one(zpool_handle_t *zhp, void *data)
 		(void) printf("]");
 		(void) printf("\n");
 	}
+}
+
+/*
+ * Print out the command history for a specific pool.
+ */
+static int
+get_history_one(zpool_handle_t *zhp, void *data)
+{
+	nvlist_t *nvhis;
+	int ret;
+	hist_cbdata_t *cb = (hist_cbdata_t *)data;
+	uint64_t off = 0;
+	boolean_t eof = B_FALSE;
+
+	cb->first = B_FALSE;
+
+	(void) printf(gettext("History for '%s':\n"), zpool_get_name(zhp));
+
+	while (!eof) {
+		if ((ret = zpool_get_history(zhp, &nvhis, &off, &eof)) != 0)
+			return (ret);
+
+		print_history_records(nvhis, cb);
+		nvlist_free(nvhis);
+	}
 	(void) printf("\n");
-	nvlist_free(nvhis);
 
 	return (ret);
 }