From ae1ba196d74f0c2677b2f16382626e17cb3a154d Mon Sep 17 00:00:00 2001
From: Xin LI <delphij@FreeBSD.org>
Date: Sat, 4 Oct 2014 07:38:59 +0000
Subject: [PATCH] 5174 add sdt probe for blocked read in dbuf_read() Reviewed
 by: Basil Crow <basil.crow@delphix.com> Reviewed by: Matthew Ahrens
 <mahrens@delphix.com> Reviewed by: Steven Hartland <killing@multiplay.co.uk>
 Reviewed by: Richard Elling <richard.elling@gmail.com> Reviewed by: Boris
 Protopopov <bprotopopov@hotmail.com> Reviewed by: Steven Hartland
 <killing@multiplay.co.uk> Reviewed by: Garrett D'Amore <garrett@damore.org>
 Approved by: Robert Mustacchi <rm@joyent.com> Author: Adam H. Leventhal
 <ahl@delphix.com>

illumos/illumos-gate@f6164ad638e7346c4ae4ba393760a897cf6eb744
---
 uts/common/fs/zfs/dbuf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/uts/common/fs/zfs/dbuf.c b/uts/common/fs/zfs/dbuf.c
index 4b0ec01a02c..8d064daf25c 100644
--- a/uts/common/fs/zfs/dbuf.c
+++ b/uts/common/fs/zfs/dbuf.c
@@ -671,6 +671,8 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
 			    db->db_state == DB_FILL) {
 				ASSERT(db->db_state == DB_READ ||
 				    (flags & DB_RF_HAVESTRUCT) == 0);
+				DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
+				    db, zio_t *, zio);
 				cv_wait(&db->db_changed, &db->db_mtx);
 			}
 			if (db->db_state == DB_UNCACHED)