blk-mq-debugfs: support rq_qos
blk-mq-debugfs has been proved as very helpful for debug some
tough issues, such as IO hang.
We have seen blk-wbt related IO hang several times, even inside
Red Hat BZ, there is such report not sovled yet, so this patch
adds support debugfs on rq_qos.
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index a32bb79..2793e91 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -23,6 +23,7 @@
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-mq-tag.h"
+#include "blk-rq-qos.h"
static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
{
@@ -856,6 +857,15 @@ int blk_mq_debugfs_register(struct request_queue *q)
goto err;
}
+ if (q->rq_qos) {
+ struct rq_qos *rqos = q->rq_qos;
+
+ while (rqos) {
+ blk_mq_debugfs_register_rqos(rqos);
+ rqos = rqos->next;
+ }
+ }
+
return 0;
err:
@@ -978,6 +988,50 @@ void blk_mq_debugfs_unregister_sched(struct request_queue *q)
q->sched_debugfs_dir = NULL;
}
+void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
+{
+ debugfs_remove_recursive(rqos->debugfs_dir);
+ rqos->debugfs_dir = NULL;
+}
+
+int blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
+{
+ struct request_queue *q = rqos->q;
+ const char *dir_name = rq_qos_id_to_name(rqos->id);
+
+ if (!q->debugfs_dir)
+ return -ENOENT;
+
+ if (rqos->debugfs_dir || !rqos->ops->debugfs_attrs)
+ return 0;
+
+ if (!q->rqos_debugfs_dir) {
+ q->rqos_debugfs_dir = debugfs_create_dir("rqos",
+ q->debugfs_dir);
+ if (!q->rqos_debugfs_dir)
+ return -ENOMEM;
+ }
+
+ rqos->debugfs_dir = debugfs_create_dir(dir_name,
+ rqos->q->rqos_debugfs_dir);
+ if (!rqos->debugfs_dir)
+ return -ENOMEM;
+
+ if (!debugfs_create_files(rqos->debugfs_dir, rqos,
+ rqos->ops->debugfs_attrs))
+ goto err;
+ return 0;
+ err:
+ blk_mq_debugfs_unregister_rqos(rqos);
+ return -ENOMEM;
+}
+
+void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q)
+{
+ debugfs_remove_recursive(q->rqos_debugfs_dir);
+ q->rqos_debugfs_dir = NULL;
+}
+
int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
struct blk_mq_hw_ctx *hctx)
{
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index a9160be..8c9012a 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -31,6 +31,10 @@ 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);
+
+int blk_mq_debugfs_register_rqos(struct rq_qos *rqos);
+void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos);
+void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q);
#else
static inline int blk_mq_debugfs_register(struct request_queue *q)
{
@@ -78,6 +82,19 @@ static inline int blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
static inline void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
{
}
+
+static inline int blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
+{
+ return 0;
+}
+
+static inline void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q)
+{
+}
#endif
#ifdef CONFIG_BLK_DEBUG_FS_ZONED
diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
index e932ef9..d169d71 100644
--- a/block/blk-rq-qos.c
+++ b/block/blk-rq-qos.c
@@ -264,6 +264,8 @@ void rq_qos_wait(struct rq_wait *rqw, void *private_data,
void rq_qos_exit(struct request_queue *q)
{
+ blk_mq_debugfs_unregister_queue_rqos(q);
+
while (q->rq_qos) {
struct rq_qos *rqos = q->rq_qos;
q->rq_qos = rqos->next;
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index 8678875..3c85f26 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -7,6 +7,10 @@
#include <linux/atomic.h>
#include <linux/wait.h>
+#include "blk-mq-debugfs.h"
+
+struct blk_mq_debugfs_attr;
+
enum rq_qos_id {
RQ_QOS_WBT,
RQ_QOS_CGROUP,
@@ -22,6 +26,9 @@ struct rq_qos {
struct request_queue *q;
enum rq_qos_id id;
struct rq_qos *next;
+#ifdef CONFIG_BLK_DEBUG_FS
+ struct dentry *debugfs_dir;
+#endif
};
struct rq_qos_ops {
@@ -33,6 +40,7 @@ struct rq_qos_ops {
void (*done_bio)(struct rq_qos *, struct bio *);
void (*cleanup)(struct rq_qos *, struct bio *);
void (*exit)(struct rq_qos *);
+ const struct blk_mq_debugfs_attr *debugfs_attrs;
};
struct rq_depth {
@@ -66,6 +74,17 @@ static inline struct rq_qos *blkcg_rq_qos(struct request_queue *q)
return rq_qos_id(q, RQ_QOS_CGROUP);
}
+static inline const char *rq_qos_id_to_name(enum rq_qos_id id)
+{
+ switch (id) {
+ case RQ_QOS_WBT:
+ return "wbt";
+ case RQ_QOS_CGROUP:
+ return "cgroup";
+ }
+ return "unknown";
+}
+
static inline void rq_wait_init(struct rq_wait *rq_wait)
{
atomic_set(&rq_wait->inflight, 0);
@@ -76,6 +95,9 @@ static inline void rq_qos_add(struct request_queue *q, struct rq_qos *rqos)
{
rqos->next = q->rq_qos;
q->rq_qos = rqos;
+
+ if (rqos->ops->debugfs_attrs)
+ blk_mq_debugfs_register_rqos(rqos);
}
static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
@@ -91,6 +113,8 @@ static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
}
prev = cur;
}
+
+ blk_mq_debugfs_unregister_rqos(rqos);
}
typedef bool (acquire_inflight_cb_t)(struct rq_wait *rqw, void *private_data);