blktrace: add an option to allow displaying cgroup path

By default we output cgroup id in blktrace. This adds an option to
display cgroup path. Since get cgroup path is a relativly heavy
operation, we don't enable it by default.

with the option enabled, blktrace will output something like this:
dd-1353  [007] d..2   293.015252:   8,0   /test/level  D   R 24 + 8 [dd]

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2017-07-12 11:49:55 -07:00 committed by Jens Axboe
parent 007cc56b7e
commit 69fd5c3917
5 changed files with 52 additions and 1 deletions

View File

@ -65,6 +65,25 @@ const struct super_operations kernfs_sops = {
.show_path = kernfs_sop_show_path,
};
/*
* Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
* number and generation
*/
struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
const union kernfs_node_id *id)
{
struct kernfs_node *kn;
kn = kernfs_find_and_get_node_by_ino(root, id->ino);
if (!kn)
return NULL;
if (kn->id.generation != id->generation) {
kernfs_put(kn);
return NULL;
}
return kn;
}
static struct inode *kernfs_fh_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{

View File

@ -613,6 +613,9 @@ static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
{
return &cgrp->kn->id;
}
void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
char *buf, size_t buflen);
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
@ -645,6 +648,9 @@ static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
{
return true;
}
static inline void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
char *buf, size_t buflen) {}
#endif /* !CONFIG_CGROUPS */
/*

View File

@ -358,6 +358,8 @@ struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns);
void kernfs_init(void);
struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
const union kernfs_node_id *id);
#else /* CONFIG_KERNFS */
static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)

View File

@ -4701,6 +4701,18 @@ static int __init cgroup_wq_init(void)
}
core_initcall(cgroup_wq_init);
void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
char *buf, size_t buflen)
{
struct kernfs_node *kn;
kn = kernfs_get_node_by_id(cgrp_dfl_root.kf_root, id);
if (!kn)
return;
kernfs_path(kn, buf, buflen);
kernfs_put(kn);
}
/*
* proc_cgroup_show()
* - Print task's cgroup paths into seq_file, one line for each hierarchy

View File

@ -48,12 +48,14 @@ static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock);
/* Select an alternative, minimalistic output than the original one */
#define TRACE_BLK_OPT_CLASSIC 0x1
#define TRACE_BLK_OPT_CGROUP 0x2
#define TRACE_BLK_OPT_CGNAME 0x4
static struct tracer_opt blk_tracer_opts[] = {
/* Default disable the minimalistic output */
{ TRACER_OPT(blk_classic, TRACE_BLK_OPT_CLASSIC) },
#ifdef CONFIG_BLK_CGROUP
{ TRACER_OPT(blk_cgroup, TRACE_BLK_OPT_CGROUP) },
{ TRACER_OPT(blk_cgname, TRACE_BLK_OPT_CGNAME) },
#endif
{ }
};
@ -1213,7 +1215,17 @@ static void blk_log_action(struct trace_iterator *iter, const char *act,
if (has_cg) {
const union kernfs_node_id *id = cgid_start(iter->ent);
trace_seq_printf(&iter->seq, "%3d,%-3d %x,%-x %2s %3s ",
if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
char blkcg_name_buf[NAME_MAX + 1] = "<...>";
cgroup_path_from_kernfs_id(id, blkcg_name_buf,
sizeof(blkcg_name_buf));
trace_seq_printf(&iter->seq, "%3d,%-3d %s %2s %3s ",
MAJOR(t->device), MINOR(t->device),
blkcg_name_buf, act, rwbs);
} else
trace_seq_printf(&iter->seq,
"%3d,%-3d %x,%-x %2s %3s ",
MAJOR(t->device), MINOR(t->device),
id->ino, id->generation, act, rwbs);
} else