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Commit 69fd5c39 authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

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: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 007cc56b

fs/kernfs/mount.c

+19 −0
Original line number Diff line number Diff line
@@ -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)

{

include/linux/cgroup.h

+6 −0
Original line number Diff line number Diff line
@@ -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 */



/*

include/linux/kernfs.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

kernel/cgroup/cgroup.c

+12 −0
Original line number Diff line number Diff line
@@ -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

kernel/trace/blktrace.c

+13 −1
Original line number Diff line number Diff line
@@ -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