tdb_expand: limit the expansion with huge records

ldb can create huge records when saving indexes.
Limit the tdb expansion to avoid consuming a lot of memory for
no good reason if the record being saved is huge.

1 files changed, 20 insertions, 5 deletions

diff --git a/lib/tdb/common/io.c b/lib/tdb/common/io.c
index 058ca6c6b5..78bbf2ec77 100644
--- a/lib/tdb/common/io.c
+++ b/lib/tdb/common/io.c
@@ -299,7 +299,7 @@ static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t ad
 int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
 {
 	struct tdb_record rec;
-	tdb_off_t offset, new_size;	
+	tdb_off_t offset, new_size, top_size, map_size;
 
 	if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n"));
@@ -309,10 +309,25 @@ int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
 	/* must know about any previous expansions by another process */
 	tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 
-	/* always make room for at least 100 more records, and at
-           least 25% more space. Round the database up to a multiple
-           of the page size */
-	new_size = MAX(tdb->map_size + size*100, tdb->map_size * 1.25);
+	/* limit size in order to avoid using up huge amounts of memory for
+	 * in memory tdbs if an oddball huge record creeps in */
+	if (size > 100 * 1024) {
+		top_size = tdb->map_size + size * 2;
+	} else {
+		top_size = tdb->map_size + size * 100;
+	}
+
+	/* always make room for at least top_size more records, and at
+	   least 25% more space. if the DB is smaller than 100MiB,
+	   otherwise grow it by 10% only. */
+	if (tdb->map_size > 100 * 1024 * 1024) {
+		map_size = tdb->map_size * 1.10;
+	} else {
+		map_size = tdb->map_size * 1.25;
+	}
+
+	/* Round the database up to a multiple of the page size */
+	new_size = MAX(top_size, map_size);
 	size = TDB_ALIGN(new_size, tdb->page_size) - tdb->map_size;
 
 	if (!(tdb->flags & TDB_INTERNAL))