Now blktrace supports outputting cgroup info for trace action and
trace message, however, it can only be enabled globally by writing
"blk_cgroup" to trace_options file, and there is no per-device API
for the new functionality.
Adding a new field (enable_cg_info) by using the pad after act_mask
in struct blk_user_trace_setup and a new attr file (cgroup_info) under
/sys/block/$dev/trace dir, so BLKTRACESETUP ioctl and sysfs file
can be used to enable cgroup info for selected block devices.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
include/linux/blktrace_api.h | 2 ++
include/uapi/linux/blktrace_api.h | 1 +
kernel/trace/blktrace.c | 14 ++++++++++++--
3 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 8804753..f120c6a 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -18,6 +18,7 @@ struct blk_trace {
unsigned long __percpu *sequence;
unsigned char __percpu *msg_data;
u16 act_mask;
+ bool enable_cg_info;
u64 start_lba;
u64 end_lba;
u32 pid;
@@ -102,6 +103,7 @@ static inline int blk_trace_init_sysfs(struct device *dev)
struct compat_blk_user_trace_setup {
char name[BLKTRACE_BDEV_SIZE];
u16 act_mask;
+ u8 enable_cg_info;
u32 buf_size;
u32 buf_nr;
compat_u64 start_lba;
diff --git a/include/uapi/linux/blktrace_api.h b/include/uapi/linux/blktrace_api.h
index 20d1490d..d9d9fca 100644
--- a/include/uapi/linux/blktrace_api.h
+++ b/include/uapi/linux/blktrace_api.h
@@ -136,6 +136,7 @@ enum {
struct blk_user_trace_setup {
char name[BLKTRACE_BDEV_SIZE]; /* output */
__u16 act_mask; /* input */
+ __u8 enable_cg_info; /* input */
__u32 buf_size; /* input */
__u32 buf_nr; /* input */
__u64 start_lba;
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 987d9a9a..f420400 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -180,7 +180,8 @@ void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
va_end(args);
- if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
+ if (!((blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP) ||
+ bt->enable_cg_info))
blkcg = NULL;
#ifdef CONFIG_BLK_CGROUP
trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
@@ -549,6 +550,7 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
bt->act_mask = buts->act_mask;
if (!bt->act_mask)
bt->act_mask = (u16) -1;
+ bt->enable_cg_info = buts->enable_cg_info;
blk_trace_setup_lba(bt, bdev);
@@ -625,6 +627,7 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
buts = (struct blk_user_trace_setup) {
.act_mask = cbuts.act_mask,
+ .enable_cg_info = cbuts.enable_cg_info,
.buf_size = cbuts.buf_size,
.buf_nr = cbuts.buf_nr,
.start_lba = cbuts.start_lba,
@@ -773,7 +776,8 @@ blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
{
struct blk_trace *bt = q->blk_trace;
- if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
+ if (!(bt && (bt->enable_cg_info ||
+ (blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))))
return NULL;
if (!bio->bi_css)
@@ -1664,6 +1668,7 @@ static BLK_TRACE_DEVICE_ATTR(act_mask);
static BLK_TRACE_DEVICE_ATTR(pid);
static BLK_TRACE_DEVICE_ATTR(start_lba);
static BLK_TRACE_DEVICE_ATTR(end_lba);
+static BLK_TRACE_DEVICE_ATTR(cgroup_info);
static struct attribute *blk_trace_attrs[] = {
&dev_attr_enable.attr,
@@ -1671,6 +1676,7 @@ static struct attribute *blk_trace_attrs[] = {
&dev_attr_pid.attr,
&dev_attr_start_lba.attr,
&dev_attr_end_lba.attr,
+ &dev_attr_cgroup_info.attr,
NULL
};
@@ -1794,6 +1800,8 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
ret = sprintf(buf, "%llu\n", q->blk_trace->start_lba);
else if (attr == &dev_attr_end_lba)
ret = sprintf(buf, "%llu\n", q->blk_trace->end_lba);
+ else if (attr == &dev_attr_cgroup_info)
+ ret = sprintf(buf, "%u\n", q->blk_trace->enable_cg_info);
out_unlock_bdev:
mutex_unlock(&q->blk_trace_mutex);
@@ -1861,6 +1869,8 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
q->blk_trace->start_lba = value;
else if (attr == &dev_attr_end_lba)
q->blk_trace->end_lba = value;
+ else if (attr == &dev_attr_cgroup_info)
+ q->blk_trace->enable_cg_info = !!value;
}
out_unlock_bdev:
--
2.9.5
