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blk-mq-debugfs: allow schedulers to register debugfs attributes
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This provides the infrastructure for schedulers to expose their internal
state through debugfs. We add a list of queue attributes and a list of
hctx attributes to struct elevator_type and wire them up when switching
schedulers.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>

Add missing seq_file.h header in blk-mq-debugfs.h

Signed-off-by: Jens Axboe <axboe@fb.com>
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Omar Sandoval authored and Jens Axboe committed May 4, 2017
1 parent 9c1051a commit d332ce0
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Showing 6 changed files with 127 additions and 17 deletions.
74 changes: 65 additions & 9 deletions block/blk-mq-debugfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,15 +24,6 @@
#include "blk-mq-debugfs.h"
#include "blk-mq-tag.h"

struct blk_mq_debugfs_attr {
const char *name;
umode_t mode;
int (*show)(void *, struct seq_file *);
ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
/* Set either .show or .seq_ops. */
const struct seq_operations *seq_ops;
};

static int blk_flags_show(struct seq_file *m, const unsigned long flags,
const char *const *flag_name, int flag_name_count)
{
Expand Down Expand Up @@ -725,6 +716,9 @@ int blk_mq_debugfs_register(struct request_queue *q)
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx->debugfs_dir && blk_mq_debugfs_register_hctx(q, hctx))
goto err;
if (q->elevator && !hctx->sched_debugfs_dir &&
blk_mq_debugfs_register_sched_hctx(q, hctx))
goto err;
}

return 0;
Expand All @@ -737,6 +731,7 @@ int blk_mq_debugfs_register(struct request_queue *q)
void blk_mq_debugfs_unregister(struct request_queue *q)
{
debugfs_remove_recursive(q->debugfs_dir);
q->sched_debugfs_dir = NULL;
q->debugfs_dir = NULL;
}

Expand Down Expand Up @@ -791,6 +786,7 @@ int blk_mq_debugfs_register_hctx(struct request_queue *q,
void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
{
debugfs_remove_recursive(hctx->debugfs_dir);
hctx->sched_debugfs_dir = NULL;
hctx->debugfs_dir = NULL;
}

Expand All @@ -815,3 +811,63 @@ void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_debugfs_unregister_hctx(hctx);
}

int blk_mq_debugfs_register_sched(struct request_queue *q)
{
struct elevator_type *e = q->elevator->type;

if (!q->debugfs_dir)
return -ENOENT;

if (!e->queue_debugfs_attrs)
return 0;

q->sched_debugfs_dir = debugfs_create_dir("sched", q->debugfs_dir);
if (!q->sched_debugfs_dir)
return -ENOMEM;

if (!debugfs_create_files(q->sched_debugfs_dir, q,
e->queue_debugfs_attrs))
goto err;

return 0;

err:
blk_mq_debugfs_unregister_sched(q);
return -ENOMEM;
}

void blk_mq_debugfs_unregister_sched(struct request_queue *q)
{
debugfs_remove_recursive(q->sched_debugfs_dir);
q->sched_debugfs_dir = NULL;
}

int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
struct blk_mq_hw_ctx *hctx)
{
struct elevator_type *e = q->elevator->type;

if (!hctx->debugfs_dir)
return -ENOENT;

if (!e->hctx_debugfs_attrs)
return 0;

hctx->sched_debugfs_dir = debugfs_create_dir("sched",
hctx->debugfs_dir);
if (!hctx->sched_debugfs_dir)
return -ENOMEM;

if (!debugfs_create_files(hctx->sched_debugfs_dir, hctx,
e->hctx_debugfs_attrs))
return -ENOMEM;

return 0;
}

void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
{
debugfs_remove_recursive(hctx->sched_debugfs_dir);
hctx->sched_debugfs_dir = NULL;
}
37 changes: 37 additions & 0 deletions block/blk-mq-debugfs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,31 @@
#define INT_BLK_MQ_DEBUGFS_H

#ifdef CONFIG_BLK_DEBUG_FS

#include <linux/seq_file.h>

struct blk_mq_debugfs_attr {
const char *name;
umode_t mode;
int (*show)(void *, struct seq_file *);
ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
/* Set either .show or .seq_ops. */
const struct seq_operations *seq_ops;
};

int blk_mq_debugfs_register(struct request_queue *q);
void blk_mq_debugfs_unregister(struct request_queue *q);
int blk_mq_debugfs_register_hctx(struct request_queue *q,
struct blk_mq_hw_ctx *hctx);
void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
int blk_mq_debugfs_register_hctxs(struct request_queue *q);
void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);

int blk_mq_debugfs_register_sched(struct request_queue *q);
void blk_mq_debugfs_unregister_sched(struct request_queue *q);
int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
struct blk_mq_hw_ctx *hctx);
void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
#else
static inline int blk_mq_debugfs_register(struct request_queue *q)
{
Expand Down Expand Up @@ -37,6 +55,25 @@ static inline int blk_mq_debugfs_register_hctxs(struct request_queue *q)
static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
{
}

static inline int blk_mq_debugfs_register_sched(struct request_queue *q)
{
return 0;
}

static inline void blk_mq_debugfs_unregister_sched(struct request_queue *q)
{
}

static inline int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
struct blk_mq_hw_ctx *hctx)
{
return 0;
}

static inline void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
{
}
#endif

#endif
24 changes: 16 additions & 8 deletions block/blk-mq-sched.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@

#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-mq-sched.h"
#include "blk-mq-tag.h"
#include "blk-wbt.h"
Expand Down Expand Up @@ -472,6 +473,8 @@ int blk_mq_sched_init_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
}
}

blk_mq_debugfs_register_sched_hctx(q, hctx);

return 0;
}

Expand All @@ -483,6 +486,8 @@ void blk_mq_sched_exit_hctx(struct request_queue *q, struct blk_mq_hw_ctx *hctx,
if (!e)
return;

blk_mq_debugfs_unregister_sched_hctx(hctx);

if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
e->type->ops.mq.exit_hctx(hctx, hctx_idx);
hctx->sched_data = NULL;
Expand Down Expand Up @@ -519,8 +524,10 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
if (ret)
goto err;

if (e->ops.mq.init_hctx) {
queue_for_each_hw_ctx(q, hctx, i) {
blk_mq_debugfs_register_sched(q);

queue_for_each_hw_ctx(q, hctx, i) {
if (e->ops.mq.init_hctx) {
ret = e->ops.mq.init_hctx(hctx, i);
if (ret) {
eq = q->elevator;
Expand All @@ -529,6 +536,7 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
return ret;
}
}
blk_mq_debugfs_register_sched_hctx(q, hctx);
}

return 0;
Expand All @@ -544,14 +552,14 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
struct blk_mq_hw_ctx *hctx;
unsigned int i;

if (e->type->ops.mq.exit_hctx) {
queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->sched_data) {
e->type->ops.mq.exit_hctx(hctx, i);
hctx->sched_data = NULL;
}
queue_for_each_hw_ctx(q, hctx, i) {
blk_mq_debugfs_unregister_sched_hctx(hctx);
if (e->type->ops.mq.exit_hctx && hctx->sched_data) {
e->type->ops.mq.exit_hctx(hctx, i);
hctx->sched_data = NULL;
}
}
blk_mq_debugfs_unregister_sched(q);
if (e->type->ops.mq.exit_sched)
e->type->ops.mq.exit_sched(e);
blk_mq_sched_tags_teardown(q);
Expand Down
1 change: 1 addition & 0 deletions include/linux/blk-mq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@ struct blk_mq_hw_ctx {

#ifdef CONFIG_BLK_DEBUG_FS
struct dentry *debugfs_dir;
struct dentry *sched_debugfs_dir;
#endif
};

Expand Down
1 change: 1 addition & 0 deletions include/linux/blkdev.h
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Original file line number Diff line number Diff line change
Expand Up @@ -579,6 +579,7 @@ struct request_queue {

#ifdef CONFIG_BLK_DEBUG_FS
struct dentry *debugfs_dir;
struct dentry *sched_debugfs_dir;
#endif

bool mq_sysfs_init_done;
Expand Down
7 changes: 7 additions & 0 deletions include/linux/elevator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,9 @@

struct io_cq;
struct elevator_type;
#ifdef CONFIG_BLK_DEBUG_FS
struct blk_mq_debugfs_attr;
#endif

/*
* Return values from elevator merger
Expand Down Expand Up @@ -144,6 +147,10 @@ struct elevator_type
char elevator_name[ELV_NAME_MAX];
struct module *elevator_owner;
bool uses_mq;
#ifdef CONFIG_BLK_DEBUG_FS
const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
#endif

/* managed by elevator core */
char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
Expand Down

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