+static char *arc_onloan_tag = "onloan";
+
+/*
+ * Loan out an anonymous arc buffer. Loaned buffers are not counted as in
+ * flight data by arc_tempreserve_space() until they are "returned". Loaned
+ * buffers must be returned to the arc before they can be used by the DMU or
+ * freed.
+ */
+arc_buf_t *
+arc_loan_buf(spa_t *spa, int size)
+{
+ arc_buf_t *buf;
+
+ buf = arc_buf_alloc(spa, size, arc_onloan_tag, ARC_BUFC_DATA);
+
+ atomic_add_64(&arc_loaned_bytes, size);
+ return (buf);
+}
+
+/*
+ * Return a loaned arc buffer to the arc.
+ */
+void
+arc_return_buf(arc_buf_t *buf, void *tag)
+{
+ arc_buf_hdr_t *hdr = buf->b_hdr;
+
+ ASSERT(hdr->b_state == arc_anon);
+ ASSERT(buf->b_data != NULL);
+ VERIFY(refcount_remove(&hdr->b_refcnt, arc_onloan_tag) == 0);
+ VERIFY(refcount_add(&hdr->b_refcnt, tag) == 1);
+
+ atomic_add_64(&arc_loaned_bytes, -hdr->b_size);
+}
+