mq-deadline: add debugfs attributes

Expose the fifo lists, cached next requests, batching state, and
dispatch list. It'd also be possible to add the sorted lists, but there
aren't already seq_file helpers for rbtrees.

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

3 files changed, 131 insertions, 2 deletions

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 8ec738f872e5..803aed4d7221 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -267,9 +267,8 @@ static const char *const rqf_name[] = {
 };
 #undef RQF_NAME
 
-int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq)
 {
-        struct request *rq = list_entry_rq(v);
         const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
         const unsigned int op = rq->cmd_flags & REQ_OP_MASK;
 
@@ -291,6 +290,12 @@ int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
         seq_puts(m, "}\n");
         return 0;
 }
+EXPORT_SYMBOL_GPL(__blk_mq_debugfs_rq_show);
+
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
+{
+        return __blk_mq_debugfs_rq_show(m, list_entry_rq(v));
+}
 EXPORT_SYMBOL_GPL(blk_mq_debugfs_rq_show);
 
 static void *hctx_dispatch_start(struct seq_file *m, loff_t *pos)
diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index dd3bbfe74f46..a182e6f97565 100644
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -14,6 +14,7 @@ struct blk_mq_debugfs_attr {
         const struct seq_operations *seq_ops;
 };
 
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq);
 int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);
 
 int blk_mq_debugfs_register(struct request_queue *q);
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 236121633ca0..1b964a387afe 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -19,6 +19,7 @@
 
 #include "blk.h"
 #include "blk-mq.h"
+#include "blk-mq-debugfs.h"
 #include "blk-mq-tag.h"
 #include "blk-mq-sched.h"
 
@@ -517,6 +518,125 @@ static struct elv_fs_entry deadline_attrs[] = {
         __ATTR_NULL
 };
 
+#ifdef CONFIG_BLK_DEBUG_FS
+#define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name)                         \
+static void *deadline_##name##_fifo_start(struct seq_file *m,           \
+                                          loff_t *pos)                  \
+        __acquires(&dd->lock)                                           \
+{                                                                       \
+        struct request_queue *q = m->private;                           \
+        struct deadline_data *dd = q->elevator->elevator_data;          \
+                                                                        \
+        spin_lock(&dd->lock);                                           \
+        return seq_list_start(&dd->fifo_list[ddir], *pos);              \
+}                                                                       \
+                                                                        \
+static void *deadline_##name##_fifo_next(struct seq_file *m, void *v,   \
+                                         loff_t *pos)                   \
+{                                                                       \
+        struct request_queue *q = m->private;                           \
+        struct deadline_data *dd = q->elevator->elevator_data;          \
+                                                                        \
+        return seq_list_next(v, &dd->fifo_list[ddir], pos);             \
+}                                                                       \
+                                                                        \
+static void deadline_##name##_fifo_stop(struct seq_file *m, void *v)    \
+        __releases(&dd->lock)                                           \
+{                                                                       \
+        struct request_queue *q = m->private;                           \
+        struct deadline_data *dd = q->elevator->elevator_data;          \
+                                                                        \
+        spin_unlock(&dd->lock);                                         \
+}                                                                       \
+                                                                        \
+static const struct seq_operations deadline_##name##_fifo_seq_ops = {   \
+        .start  = deadline_##name##_fifo_start,                         \
+        .next   = deadline_##name##_fifo_next,                          \
+        .stop   = deadline_##name##_fifo_stop,                          \
+        .show   = blk_mq_debugfs_rq_show,                               \
+};                                                                      \
+                                                                        \
+static int deadline_##name##_next_rq_show(void *data,                   \
+                                          struct seq_file *m)           \
+{                                                                       \
+        struct request_queue *q = data;                                 \
+        struct deadline_data *dd = q->elevator->elevator_data;          \
+        struct request *rq = dd->next_rq[ddir];                         \
+                                                                        \
+        if (rq)                                                         \
+                __blk_mq_debugfs_rq_show(m, rq);                        \
+        return 0;                                                       \
+}
+DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
+DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
+#undef DEADLINE_DEBUGFS_DDIR_ATTRS
+
+static int deadline_batching_show(void *data, struct seq_file *m)
+{
+        struct request_queue *q = data;
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        seq_printf(m, "%u\n", dd->batching);
+        return 0;
+}
+
+static int deadline_starved_show(void *data, struct seq_file *m)
+{
+        struct request_queue *q = data;
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        seq_printf(m, "%u\n", dd->starved);
+        return 0;
+}
+
+static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
+        __acquires(&dd->lock)
+{
+        struct request_queue *q = m->private;
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        spin_lock(&dd->lock);
+        return seq_list_start(&dd->dispatch, *pos);
+}
+
+static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        struct request_queue *q = m->private;
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        return seq_list_next(v, &dd->dispatch, pos);
+}
+
+static void deadline_dispatch_stop(struct seq_file *m, void *v)
+        __releases(&dd->lock)
+{
+        struct request_queue *q = m->private;
+        struct deadline_data *dd = q->elevator->elevator_data;
+
+        spin_unlock(&dd->lock);
+}
+
+static const struct seq_operations deadline_dispatch_seq_ops = {
+        .start  = deadline_dispatch_start,
+        .next   = deadline_dispatch_next,
+        .stop   = deadline_dispatch_stop,
+        .show   = blk_mq_debugfs_rq_show,
+};
+
+#define DEADLINE_QUEUE_DDIR_ATTRS(name)                                         \
+        {#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
+        {#name "_next_rq", 0400, deadline_##name##_next_rq_show}
+static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
+        DEADLINE_QUEUE_DDIR_ATTRS(read),
+        DEADLINE_QUEUE_DDIR_ATTRS(write),
+        {"batching", 0400, deadline_batching_show},
+        {"starved", 0400, deadline_starved_show},
+        {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
+        {},
+};
+#undef DEADLINE_QUEUE_DDIR_ATTRS
+#endif
+
 static struct elevator_type mq_deadline = {
         .ops.mq = {
                 .insert_requests        = dd_insert_requests,
@@ -533,6 +653,9 @@ static struct elevator_type mq_deadline = {
         },
 
         .uses_mq        = true,
+#ifdef CONFIG_BLK_DEBUG_FS
+        .queue_debugfs_attrs = deadline_queue_debugfs_attrs,
+#endif
         .elevator_attrs = deadline_attrs,
         .elevator_name = "mq-deadline",
         .elevator_owner = THIS_MODULE,