[tip:tracing/core] blktrace: support per-partition tracing for ftrace plugin

tip-bot for Li Zefan
2009-04-15T10:13:55Z

Commit-ID: 1411074bef90ccb3b709b98965ac79508b51c452
Gitweb: http://git.kernel.org/tip/1411074bef90ccb3b709b98965ac79508b51c452
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Tue, 14 Apr 2009 13:59:34 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 15 Apr 2009 09:38:44 +0200

blktrace: support per-partition tracing for ftrace plugin

The previous patch adds support to trace a single partition for
relay+ioctl blktrace, and this patch is for ftrace plugin blktrace:

# echo 1 > /sys/block/sda/sda7/enable
# cat start_lba
102398373
# cat end_lba
102703545

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Shawn Du <duyuyang@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
LKML-Reference: <49E42646.4060608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
kernel/trace/blktrace.c | 39 +++++++++++++++++++++++++--------------
1 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index e932654..d109898 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -403,6 +403,23 @@ static struct rchan_callbacks blk_relay_callbacks = {
.remove_buf_file = blk_remove_buf_file_callback,
};

+static void blk_trace_setup_lba(struct blk_trace *bt,
+ struct block_device *bdev)
+{
+ struct hd_struct *part = NULL;
+
+ if (bdev)
+ part = bdev->bd_part;
+
+ if (part) {
+ bt->start_lba = part->start_sect;
+ bt->end_lba = part->start_sect + part->nr_sects;
+ } else {
+ bt->start_lba = 0;
+ bt->end_lba = -1ULL;
+ }
+}
+
/*
* Setup everything required to start tracing
*/
@@ -413,7 +430,6 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
struct blk_trace *old_bt, *bt = NULL;
struct dentry *dir = NULL;
int ret, i;
- struct hd_struct *part = NULL;

if (!buts->buf_size || !buts->buf_nr)
return -EINVAL;
@@ -482,14 +498,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!bt->act_mask)
bt->act_mask = (u16) -1;

- if (bdev)
- part = bdev->bd_part;
-
- if (part) {
- bt->start_lba = part->start_sect;
- bt->end_lba = part->start_sect + part->nr_sects;
- } else
- bt->end_lba = -1ULL;
+ blk_trace_setup_lba(bt, bdev);

/* overwrite with user settings */
if (buts->start_lba)
@@ -1370,7 +1379,8 @@ static int blk_trace_remove_queue(struct request_queue *q)
/*
* Setup everything required to start tracing
*/
-static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
+static int blk_trace_setup_queue(struct request_queue *q,
+ struct block_device *bdev)
{
struct blk_trace *old_bt, *bt = NULL;
int ret = -ENOMEM;
@@ -1383,9 +1393,10 @@ static int blk_trace_setup_queue(struct request_queue *q, dev_t dev)
if (!bt->msg_data)
goto free_bt;

- bt->dev = dev;
+ bt->dev = bdev->bd_dev;
bt->act_mask = (u16)-1;
- bt->end_lba = -1ULL;
+
+ blk_trace_setup_lba(bt, bdev);

old_bt = xchg(&q->blk_trace, bt);
if (old_bt != NULL) {
@@ -1602,7 +1613,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,

if (attr == &dev_attr_enable) {
if (value)
- ret = blk_trace_setup_queue(q, bdev->bd_dev);
+ ret = blk_trace_setup_queue(q, bdev);
else
ret = blk_trace_remove_queue(q);
goto out_unlock_bdev;
@@ -1610,7 +1621,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,

ret = 0;
if (q->blk_trace == NULL)
- ret = blk_trace_setup_queue(q, bdev->bd_dev);
+ ret = blk_trace_setup_queue(q, bdev);

if (ret == 0) {
if (attr == &dev_attr_act_mask)