From: Shaohua Li <shli@xxxxxx>
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@xxxxxx>
---
fs/kernfs/mount.c | 19 +++++++++++++++++++
include/linux/cgroup.h | 6 ++++++
include/linux/kernfs.h | 2 ++
kernel/cgroup/cgroup.c | 12 ++++++++++++
kernel/trace/blktrace.c | 14 +++++++++++++-
5 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index d24d816..4c1636e 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -76,6 +76,25 @@ void kernfs_encode_node_id(struct kernfs_node *kn, struct kernfs_node_id *id)
id->gen = kn->generation;
}
+/*
+ * Similar like 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 struct kernfs_node_id *id)
+{
+ struct kernfs_node *kn;
+
+ kn = kernfs_get_node_by_ino(root, id->ino);
+ if (!kn)
+ return NULL;
+ if (kn->generation != id->gen) {
+ kernfs_put(kn);
+ return NULL;
+ }
+ return kn;
+}
+
static struct inode *kernfs_fh_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c30dda8..56390c8 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -593,6 +593,9 @@ static inline struct kernfs_node_id *cgroup_get_node_id(struct cgroup *cgrp)
{
return &cgrp->node_id;
}
+
+void cgroup_path_from_node_id(const struct kernfs_node_id *id,
+ char *buf, size_t buflen);
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
@@ -625,6 +628,9 @@ static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
{
return true;
}
+
+static inline void cgroup_path_from_node_id(const struct kernfs_node_id *id,
+ char *buf, size_t buflen) {}
#endif /* !CONFIG_CGROUPS */
/*
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 932d89f..1c9397d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -346,6 +346,8 @@ struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns);
void kernfs_init(void);
void kernfs_encode_node_id(struct kernfs_node *kn, struct kernfs_node_id *id);
+struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
+ const struct kernfs_node_id *id);
#else /* CONFIG_KERNFS */
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 489672d..7f91ad1 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4604,6 +4604,18 @@ static int __init cgroup_wq_init(void)
}
core_initcall(cgroup_wq_init);
+void cgroup_path_from_node_id(const struct 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
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index e351837..18cbc02 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -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
{ }
};
@@ -1212,7 +1214,17 @@ static void blk_log_action(struct trace_iterator *iter, const char *act,
if (has_cg) {
const struct kernfs_node_id *id = cgid_start(iter->ent);
- trace_seq_printf(&iter->seq, "%3d,%-3d %8x,%-8x %2s %3s ",
+ if (blk_tracer_flags.val & TRACE_BLK_OPT_CGNAME) {
+ char blkcg_name_buf[NAME_MAX + 1] = "<...>";
+
+ cgroup_path_from_node_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 %8x,%-8x %2s %3s ",
MAJOR(t->device), MINOR(t->device),
id->ino, id->gen, act, rwbs);
} else
--
2.9.3
