Re: [PATCH 07/10] blk-mq: move tags and sched_tags info from sysfs to debugfs

[Hannes Reinecke]

On 01/23/2017 07:59 PM, Omar Sandoval wrote:
> From: Omar Sandoval 
> 
> These are very tied to the blk-mq tag implementation, so exposing them
> to sysfs isn't a great idea. Move the debugging information to debugfs
> and add basic entries for the number of tags and the number of reserved
> tags to sysfs.
> 
> Signed-off-by: Omar Sandoval 
> ---
>  block/blk-mq-debugfs.c | 70 
> ++
>  block/blk-mq-sysfs.c   | 33 
>  block/blk-mq-tag.c | 27 ---
>  block/blk-mq-tag.h |  1 -
>  4 files changed, 86 insertions(+), 45 deletions(-)
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
-- 
Dr. Hannes ReineckeTeamlead Storage & Networking
h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
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[PATCH 07/10] blk-mq: move tags and sched_tags info from sysfs to debugfs

[Omar Sandoval]

From: Omar Sandoval 

These are very tied to the blk-mq tag implementation, so exposing them
to sysfs isn't a great idea. Move the debugging information to debugfs
and add basic entries for the number of tags and the number of reserved
tags to sysfs.

Signed-off-by: Omar Sandoval 
---
 block/blk-mq-debugfs.c | 70 ++
 block/blk-mq-sysfs.c   | 33 
 block/blk-mq-tag.c | 27 ---
 block/blk-mq-tag.h |  1 -
 4 files changed, 86 insertions(+), 45 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 4ee6ab28f56f..48b3a11402fb 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -20,6 +20,7 @@
 
 #include 
 #include "blk-mq.h"
+#include "blk-mq-tag.h"
 
 struct blk_mq_debugfs_attr {
const char *name;
@@ -148,6 +149,73 @@ static const struct file_operations hctx_ctx_map_fops = {
.release= single_release,
 };
 
+static void blk_mq_debugfs_tags_show(struct seq_file *m,
+struct blk_mq_tags *tags)
+{
+   seq_printf(m, "nr_tags=%u\n", tags->nr_tags);
+   seq_printf(m, "nr_reserved_tags=%u\n", tags->nr_reserved_tags);
+   seq_printf(m, "active_queues=%d\n",
+  atomic_read(>active_queues));
+
+   seq_puts(m, "\nbitmap_tags:\n");
+   sbitmap_queue_show(m, >bitmap_tags);
+
+   if (tags->nr_reserved_tags) {
+   seq_puts(m, "\nbreserved_tags:\n");
+   sbitmap_queue_show(m, >breserved_tags);
+   }
+}
+
+static int hctx_tags_show(struct seq_file *m, void *v)
+{
+   struct blk_mq_hw_ctx *hctx = m->private;
+   struct request_queue *q = hctx->queue;
+
+   mutex_lock(>sysfs_lock);
+   if (hctx->tags)
+   blk_mq_debugfs_tags_show(m, hctx->tags);
+   mutex_unlock(>sysfs_lock);
+
+   return 0;
+}
+
+static int hctx_tags_open(struct inode *inode, struct file *file)
+{
+   return single_open(file, hctx_tags_show, inode->i_private);
+}
+
+static const struct file_operations hctx_tags_fops = {
+   .open   = hctx_tags_open,
+   .read   = seq_read,
+   .llseek = seq_lseek,
+   .release= single_release,
+};
+
+static int hctx_sched_tags_show(struct seq_file *m, void *v)
+{
+   struct blk_mq_hw_ctx *hctx = m->private;
+   struct request_queue *q = hctx->queue;
+
+   mutex_lock(>sysfs_lock);
+   if (hctx->sched_tags)
+   blk_mq_debugfs_tags_show(m, hctx->sched_tags);
+   mutex_unlock(>sysfs_lock);
+
+   return 0;
+}
+
+static int hctx_sched_tags_open(struct inode *inode, struct file *file)
+{
+   return single_open(file, hctx_sched_tags_show, inode->i_private);
+}
+
+static const struct file_operations hctx_sched_tags_fops = {
+   .open   = hctx_sched_tags_open,
+   .read   = seq_read,
+   .llseek = seq_lseek,
+   .release= single_release,
+};
+
 static void *ctx_rq_list_start(struct seq_file *m, loff_t *pos)
 {
struct blk_mq_ctx *ctx = m->private;
@@ -194,6 +262,8 @@ static const struct blk_mq_debugfs_attr 
blk_mq_debugfs_hctx_attrs[] = {
{"flags", 0400, _flags_fops},
{"dispatch", 0400, _dispatch_fops},
{"ctx_map", 0400, _ctx_map_fops},
+   {"tags", 0400, _tags_fops},
+   {"sched_tags", 0400, _sched_tags_fops},
 };
 
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index ee3694d8c4ee..a0ae1f536ed0 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -184,17 +184,16 @@ static ssize_t blk_mq_hw_sysfs_dispatched_show(struct 
blk_mq_hw_ctx *hctx,
return page - start_page;
 }
 
-static ssize_t blk_mq_hw_sysfs_sched_tags_show(struct blk_mq_hw_ctx *hctx, 
char *page)
+static ssize_t blk_mq_hw_sysfs_nr_tags_show(struct blk_mq_hw_ctx *hctx,
+   char *page)
 {
-   if (hctx->sched_tags)
-   return blk_mq_tag_sysfs_show(hctx->sched_tags, page);
-
-   return 0;
+   return sprintf(page, "%u\n", hctx->tags->nr_tags);
 }
 
-static ssize_t blk_mq_hw_sysfs_tags_show(struct blk_mq_hw_ctx *hctx, char 
*page)
+static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx 
*hctx,
+char *page)
 {
-   return blk_mq_tag_sysfs_show(hctx->tags, page);
+   return sprintf(page, "%u\n", hctx->tags->nr_reserved_tags);
 }
 
 static ssize_t blk_mq_hw_sysfs_active_show(struct blk_mq_hw_ctx *hctx, char 
*page)
@@ -293,18 +292,18 @@ static struct blk_mq_hw_ctx_sysfs_entry 
blk_mq_hw_sysfs_dispatched = {
.attr = {.name = "dispatched", .mode = S_IRUGO },
.show = blk_mq_hw_sysfs_dispatched_show,
 };
+static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = {
+   .attr = {.name = "nr_tags", .mode = S_IRUGO },
+