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

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
......@@ -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;
......
......@@ -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__ */
......
......@@ -1644,3 +1644,8 @@ out:
return ret ? ret : count;
}
int blk_trace_init_sysfs(struct device *dev)
{
return sysfs_create_group(&dev->kobj, &blk_trace_attr_group);
}
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