From 4b5db44a063baeace0690456f8f7a46681659fcf Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@suse.de>
Date: Mon, 3 Oct 2005 14:06:07 +0200
Subject: [PATCH] [PATCH] blktrace: allow for unaligned events

Unfortunately it looks like we have to support this for now,
as it appears relayfs will still miss events on buffer wraps
for the read cases.
---
 blktrace.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/blktrace.c b/blktrace.c
index 559cb7f..852c925 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -292,6 +292,22 @@ static void *extract_data(struct thread_information *tip, int nb)
 	return NULL;
 }
 
+static int get_event(struct thread_information *tip, struct blk_io_trace *bit)
+{
+	void *p = &bit->sequence;
+
+	do {
+		if (read_data(tip, bit, sizeof(bit->magic)))
+			return -1;
+
+	} while (!CHECK_MAGIC(bit));
+
+	if (!read_data(tip, p, sizeof(*bit) - sizeof(bit->magic)))
+		return 0;
+
+	return -1;
+}
+
 static inline void tip_fd_unlock(struct thread_information *tip)
 {
 	if (tip->fd_lock)
@@ -333,7 +349,7 @@ static void *extract(void *arg)
 
 	pdu_data = NULL;
 	while (!is_done()) {
-		if (read_data(tip, &t, sizeof(t)))
+		if (get_event(tip, &t))
 			break;
 
 		if (verify_trace(&t))
-- 
2.25.1