[PATCH 10/11] blktrace: add an option to allow displying cgroup path
From: Shaohua Li <shli@kernel.org>
Date: 2017-06-02 21:54:49
Also in:
lkml
Subsystem:
block layer, control group (cgroup), filesystems (vfs and infrastructure), kernfs, the rest, tracing · Maintainers:
Jens Axboe, Tejun Heo, Johannes Weiner, Michal Koutný, Alexander Viro, Christian Brauner, Greg Kroah-Hartman, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Shaohua Li <redacted> 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 <redacted> --- 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