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Commit 1d54ad6d authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

blktrace: add trace/ to /sys/block/sda 



Impact: allow ftrace-plugin blktrace to trace device-mapper devices

To trace a single partition:
  # echo 1 > /sys/block/sda/sda1/enable

To trace the whole sda instead:
  # echo 1 > /sys/block/sda/enable

Thus we also fix an issue reported by Ted, that ftrace-plugin blktrace
can't be used to trace device-mapper devices.

Now:

  # echo 1 > /sys/block/dm-0/trace/enable
  echo: write error: No such device or address
  # mount -t ext4 /dev/dm-0 /mnt
  # echo 1 > /sys/block/dm-0/trace/enable
  # echo blk > /debug/tracing/current_tracer

Reported-by: default avatarTheodore Tso <tytso@mit.edu>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatar"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: <49E42665.6020506@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9908c309

block/blk-sysfs.c

+6 −1
Original line number Diff line number Diff line
@@ -387,16 +387,21 @@ struct kobj_type blk_queue_ktype = { 
int blk_register_queue(struct gendisk *disk)

{

	int ret;

	struct device *dev = disk_to_dev(disk);



	struct request_queue *q = disk->queue;



	if (WARN_ON(!q))

		return -ENXIO;



	ret = blk_trace_init_sysfs(dev);

	if (ret)

		return ret;



	if (!q->request_fn)

		return 0;



	ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),

	ret = kobject_add(&q->kobj, kobject_get(&dev->kobj),

			  "%s", "queue");

	if (ret < 0)

		return ret;

include/linux/blktrace_api.h

+6 −0
Original line number Diff line number Diff line
@@ -198,6 +198,7 @@ extern int blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
			   char __user *arg);

extern int blk_trace_startstop(struct request_queue *q, int start);

extern int blk_trace_remove(struct request_queue *q);

extern int blk_trace_init_sysfs(struct device *dev);



extern struct attribute_group blk_trace_attr_group;
@@ -210,6 +211,11 @@ extern struct attribute_group blk_trace_attr_group; 
# define blk_trace_startstop(q, start)			(-ENOTTY)

# define blk_trace_remove(q)				(-ENOTTY)

# define blk_add_trace_msg(q, fmt, ...)			do { } while (0)

static inline int blk_trace_init_sysfs(struct device *dev)

{

	return 0;

}



#endif /* CONFIG_BLK_DEV_IO_TRACE */



#endif /* __KERNEL__ */

kernel/trace/blktrace.c

+5 −0
Original line number Diff line number Diff line
@@ -1644,3 +1644,8 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, 
	return ret ? ret : count;

}



int blk_trace_init_sysfs(struct device *dev)

{

	return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);

}