blk-mq-debugfs: allow schedulers to register debugfs attributes

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>

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 260cf76..a3b8871 100644 (file)
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -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)
 {
@@ -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;
@@ -737,6 +731,7 @@ err:
 void blk_mq_debugfs_unregister(struct request_queue *q)
 {
        debugfs_remove_recursive(q->debugfs_dir);
+       q->sched_debugfs_dir = NULL;
        q->debugfs_dir = NULL;
 }
 
@@ -791,6 +786,7 @@ err:
 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;
 }
 
@@ -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;
+}

diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 596e9b1..a5ac21c 100644 (file)
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -2,6 +2,18 @@
 #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,
@@ -9,6 +21,12 @@ int blk_mq_debugfs_register_hctx(struct request_queue *q,
 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)
 {
@@ -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

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index e79e9f1..1f5b692 100644 (file)
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -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"
@@ -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;
 }
 
@@ -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;
@@ -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;
@@ -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;
@@ -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);

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index de8ed9a..c47aa24 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -60,6 +60,7 @@ struct blk_mq_hw_ctx {
 
 #ifdef CONFIG_BLK_DEBUG_FS
        struct dentry           *debugfs_dir;
+       struct dentry           *sched_debugfs_dir;
 #endif
 };
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b49a79a..80ae958 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -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;

diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index d448403..9ec5e22 100644 (file)
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -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
@@ -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" */