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

tip-bot for Shawn Du
2009-04-16T16:16:21Z

Commit-ID: d0deef5b14af7d5bbd0003a0a2a1a32326e20a6d
Gitweb: http://git.kernel.org/tip/d0deef5b14af7d5bbd0003a0a2a1a32326e20a6d
Author: Shawn Du <duyuyang@gmail.com>
AuthorDate: Tue, 14 Apr 2009 13:58:56 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 16 Apr 2009 10:10:57 +0200

blktrace: support per-partition tracing

Though one can specify '-d /dev/sda1' when using blktrace, it still
traces the whole sda.

To support per-partition tracing, when we start tracing, we initialize
bt->start_lba and bt->end_lba to the start and end sector of that
partition.

Note some actions are per device, thus we don't filter 0-sector events.

The original patch and discussion can be found here:
http://marc.info/?l=linux-btrace&m=122949374214540&w=2

Signed-off-by: Shawn Du <duyuyang@gmail.com>
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: Jens Axboe <jens.axboe@oracle.com>
LKML-Reference: <49E42620.4050701@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
block/compat_ioctl.c | 2 +-
drivers/scsi/sg.c | 1 +
include/linux/blktrace_api.h | 24 +++++++++++++-----------
kernel/trace/blktrace.c | 29 +++++++++++++++++++++--------
4 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index f87615d..f8c218c 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -568,7 +568,7 @@ static int compat_blk_trace_setup(struct block_device *bdev, char __user *arg)
memcpy(&buts.name, &cbuts.name, 32);

mutex_lock(&bdev->bd_mutex);
- ret = do_blk_trace_setup(q, b, bdev->bd_dev, &buts);
+ ret = do_blk_trace_setup(q, b, bdev->bd_dev, bdev, &buts);
mutex_unlock(&bdev->bd_mutex);
if (ret)
return ret;
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 82312df..49c9873 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1065,6 +1065,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
return blk_trace_setup(sdp->device->request_queue,
sdp->disk->disk_name,
MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
+ NULL,
(char *)arg);
case BLKTRACESTART:
return blk_trace_startstop(sdp->device->request_queue, 1);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index d960889..267edc4 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -165,8 +165,9 @@ struct blk_trace {

extern int blk_trace_ioctl(struct block_device *, unsigned, char __user *);
extern void blk_trace_shutdown(struct request_queue *);
-extern int do_blk_trace_setup(struct request_queue *q,
- char *name, dev_t dev, struct blk_user_trace_setup *buts);
+extern int do_blk_trace_setup(struct request_queue *q, char *name,
+ dev_t dev, struct block_device *bdev,
+ struct blk_user_trace_setup *buts);
extern void __trace_note_message(struct blk_trace *, const char *fmt, ...);

/**
@@ -193,6 +194,7 @@ extern void __trace_note_message(struct blk_trace *, const char *fmt, ...);
extern void blk_add_driver_data(struct request_queue *q, struct request *rq,
void *data, size_t len);
extern int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
+ struct block_device *bdev,
char __user *arg);
extern int blk_trace_startstop(struct request_queue *q, int start);
extern int blk_trace_remove(struct request_queue *q);
@@ -200,15 +202,15 @@ extern int blk_trace_remove(struct request_queue *q);
extern struct attribute_group blk_trace_attr_group;

#else /* !CONFIG_BLK_DEV_IO_TRACE */
-#define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
-#define blk_trace_shutdown(q) do { } while (0)
-#define do_blk_trace_setup(q, name, dev, buts) (-ENOTTY)
-#define blk_add_driver_data(q, rq, data, len) do {} while (0)
-#define blk_trace_setup(q, name, dev, arg) (-ENOTTY)
-#define blk_trace_startstop(q, start) (-ENOTTY)
-#define blk_trace_remove(q) (-ENOTTY)
-#define blk_add_trace_msg(q, fmt, ...) do { } while (0)
-
+# define blk_trace_ioctl(bdev, cmd, arg) (-ENOTTY)
+# define blk_trace_shutdown(q) do { } while (0)
+# define do_blk_trace_setup(q, name, dev, bdev, buts) (-ENOTTY)
+# define blk_add_driver_data(q, rq, data, len) do {} while (0)
+# define blk_trace_setup(q, name, dev, bdev, arg) (-ENOTTY)
+# define blk_trace_startstop(q, start) (-ENOTTY)
+# define blk_trace_remove(q) (-ENOTTY)
+# define blk_add_trace_msg(q, fmt, ...) do { } while (0)
#endif /* CONFIG_BLK_DEV_IO_TRACE */
+
#endif /* __KERNEL__ */
#endif
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 2b98195..e932654 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -147,7 +147,7 @@ static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
{
if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
return 1;
- if (sector < bt->start_lba || sector > bt->end_lba)
+ if (sector && (sector < bt->start_lba || sector > bt->end_lba))
return 1;
if (bt->pid && pid != bt->pid)
return 1;
@@ -192,7 +192,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
what |= MASK_TC_BIT(rw, DISCARD);

pid = tsk->pid;
- if (unlikely(act_log_check(bt, what, sector, pid)))
+ if (act_log_check(bt, what, sector, pid))
return;
cpu = raw_smp_processor_id();

@@ -407,11 +407,13 @@ static struct rchan_callbacks blk_relay_callbacks = {
* Setup everything required to start tracing
*/
int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
- struct blk_user_trace_setup *buts)
+ struct block_device *bdev,
+ struct blk_user_trace_setup *buts)
{
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;
@@ -480,11 +482,21 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!bt->act_mask)
bt->act_mask = (u16) -1;

- bt->start_lba = buts->start_lba;
- bt->end_lba = buts->end_lba;
- if (!bt->end_lba)
+ 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;

+ /* overwrite with user settings */
+ if (buts->start_lba)
+ bt->start_lba = buts->start_lba;
+ if (buts->end_lba)
+ bt->end_lba = buts->end_lba;
+
bt->pid = buts->pid;
bt->trace_state = Blktrace_setup;

@@ -505,6 +517,7 @@ err:
}

int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
+ struct block_device *bdev,
char __user *arg)
{
struct blk_user_trace_setup buts;
@@ -514,7 +527,7 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (ret)
return -EFAULT;

- ret = do_blk_trace_setup(q, name, dev, &buts);
+ ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
if (ret)
return ret;

@@ -582,7 +595,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
switch (cmd) {
case BLKTRACESETUP:
bdevname(bdev, b);
- ret = blk_trace_setup(q, b, bdev->bd_dev, arg);
+ ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
break;
case BLKTRACESTART:
start = 1;