>From 4b2e639af0c6cb8c099003c5a3fda388022e1b49 Mon Sep 17 00:00:00 2001
From: Alan D. Brunelle <alan.brunelle@xxxxxx>
Date: Fri, 23 May 2008 16:27:34 -0400
Subject: [PATCH] Added in MESSAGE notes for blktraces - sample message for elv switch
Allows messages to be inserted into blktrace streams. Can be used to
annotate parts separations in the blktrace stream.
(Needs cleaning up: separate elevator mods into a separate patch.)
Signed-off-by: Alan D. Brunelle <alan.brunelle@xxxxxx>
---
block/blktrace.c | 6 ++++++
block/elevator.c | 4 ++++
include/linux/blktrace_api.h | 20 ++++++++++++++++++++
3 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/block/blktrace.c b/block/blktrace.c
index b2cbb4e..37dec26 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -75,6 +75,12 @@ static void trace_note_time(struct blk_trace *bt)
local_irq_restore(flags);
}
+void __trace_note_message(struct blk_trace *bt, char *msg)
+{
+ trace_note(bt, 0, BLK_TN_MESSAGE, msg, strlen(msg));
+}
+EXPORT_SYMBOL_GPL(__trace_note_message);
+
static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
pid_t pid)
{
diff --git a/block/elevator.c b/block/elevator.c
index 980f8ae..d9d4091 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1051,6 +1051,7 @@ EXPORT_SYMBOL_GPL(elv_unregister);
*/
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
{
+ char msg[ELV_NAME_MAX + 16];
elevator_t *old_elevator, *e;
void *data;
@@ -1110,6 +1111,9 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
spin_unlock_irq(q->queue_lock);
+ sprintf(msg, "elv switch: %s", e->elevator_type->elevator_name);
+ blk_add_trace_msg(q, msg);
+
return 1;
fail_register:
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index cfc3147..4409c6a 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -55,6 +55,7 @@ enum blktrace_act {
enum blktrace_notify {
__BLK_TN_PROCESS = 0, /* establish pid/name mapping */
__BLK_TN_TIMESTAMP, /* include system clock */
+ __BLK_TN_MESSAGE, /* Character string message */
};
@@ -79,6 +80,7 @@ enum blktrace_notify {
#define BLK_TN_PROCESS (__BLK_TN_PROCESS | BLK_TC_ACT(BLK_TC_NOTIFY))
#define BLK_TN_TIMESTAMP (__BLK_TN_TIMESTAMP | BLK_TC_ACT(BLK_TC_NOTIFY))
+#define BLK_TN_MESSAGE (__BLK_TN_MESSAGE | BLK_TC_ACT(BLK_TC_NOTIFY))
#define BLK_IO_TRACE_MAGIC 0x65617400
#define BLK_IO_TRACE_VERSION 0x07
@@ -144,6 +146,7 @@ struct blk_user_trace_setup {
#ifdef __KERNEL__
#if defined(CONFIG_BLK_DEV_IO_TRACE)
+extern void __trace_note_message(struct blk_trace *, char *);
extern int blk_trace_ioctl(struct block_device *, unsigned, char __user *);
extern void blk_trace_shutdown(struct request_queue *);
extern void __blk_add_trace(struct blk_trace *, sector_t, int, int, u32, int, int, void *);
@@ -152,6 +155,22 @@ extern int do_blk_trace_setup(struct request_queue *q,
/**
+ * blk_add_trace_msg - Add a (simple) message to the blktrace stream
+ * @q: queue the io is for
+ * @msg: characters to send
+ *
+ * Description:
+ * Records a (simple) message onto the blktrace stream.
+ *
+ **/
+static inline void blk_add_trace_msg(struct request_queue *q, char *msg)
+{
+ struct blk_trace *bt = q->blk_trace;
+ if (unlikely(bt))
+ __trace_note_message(bt, msg);
+}
+
+/**
* blk_add_trace_rq - Add a trace for a request oriented action
* @q: queue the io is for
* @rq: the source request
@@ -288,6 +307,7 @@ extern int blk_trace_startstop(struct request_queue *q, int start);
extern int blk_trace_remove(struct request_queue *q);
#else /* !CONFIG_BLK_DEV_IO_TRACE */
+#define blk_add_trace_msg(q, msg) do { } while (0)
#define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
#define blk_trace_shutdown(q) do { } while (0)
#define blk_add_trace_rq(q, rq, what) do { } while (0)
--
1.5.4.3
