Filesystems like XFS can implement atomic write I/O using either
REQ_ATOMIC flag set in the bio or via CoW operation. It will be useful
if we have a flag in trace events to distinguish between the two. This
patch adds char 'U' (Untorn writes) to rwbs field of the trace events
if REQ_ATOMIC flag is set in the bio.
<W/ REQ_ATOMIC>
=================
xfs_io-4238 [009] ..... 4148.126843: block_rq_issue: 259,0 WFSU 16384 () 768 + 32 none,0,0 [xfs_io]
<idle>-0 [009] d.h1. 4148.129864: block_rq_complete: 259,0 WFSU () 768 + 32 none,0,0 [0]
<W/O REQ_ATOMIC>
===============
xfs_io-4237 [010] ..... 4143.325616: block_rq_issue: 259,0 WS 16384 () 768 + 32 none,0,0 [xfs_io]
<idle>-0 [010] d.H1. 4143.329138: block_rq_complete: 259,0 WS () 768 + 32 none,0,0 [0]
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
v1 -> v2:
=========
1. Changed char 'a' to 'U' (Untorn Writes)
include/trace/events/block.h | 2 +-
kernel/trace/blktrace.c | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/block.h b/include/trace/events/block.h
index bd0ea07338eb..de538b110ea1 100644
--- a/include/trace/events/block.h
+++ b/include/trace/events/block.h
@@ -11,7 +11,7 @@
#include <linux/tracepoint.h>
#include <uapi/linux/ioprio.h>
-#define RWBS_LEN 8
+#define RWBS_LEN 9
#define IOPRIO_CLASS_STRINGS \
{ IOPRIO_CLASS_NONE, "none" }, \
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 3679a6d18934..fc62a9767203 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -1896,6 +1896,8 @@ void blk_fill_rwbs(char *rwbs, blk_opf_t opf)
rwbs[i++] = 'S';
if (opf & REQ_META)
rwbs[i++] = 'M';
+ if (opf & REQ_ATOMIC)
+ rwbs[i++] = 'U';
rwbs[i] = '\0';
}
--
2.39.5
