lkml.org 
[lkml]   [2019]   [Jul]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC PATCH 2/3] md: export inflight io counters and internal stats in debugfs
Date
There are so many io counters and stats/flags in md, so I think
export these info in debugfs will be helpful for online-debugging,
especially when the vmlinux and crash utility are not available.
And these files can also be utilized during code understanding.

Debug info are divided into two debugfs files:
* iostat
contains io counters and io related stats (e.g., mddev->pending_writes
and the active status of mddev->sb_wait)
* stat
contains internal stats or flags (e.g., mddev->sb_flags)

These two debugfs files will be created both by md-core and the used
md-personality for each md device. This patch creates debug files
for md-core under /sys/kernel/debug/block/mdX, and the following patch
will creates these files for RAID1. The following lines show the hierarchy
of debugfs files created for a RAID1 device:

$ pwd
/sys/kernel/debug/block/md0
$ tree
.
├── iostat
├── raid1
│   ├── iostat
│   └── stat
└── stat

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
drivers/md/md.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/md/md.h | 1 +
2 files changed, 66 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9801d540fea1..dceb8fd59ba0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -64,11 +64,14 @@
#include "md.h"
#include "md-bitmap.h"
#include "md-cluster.h"
+#include "md-debugfs.h"

#ifndef MODULE
static void autostart_arrays(int part);
#endif

+extern struct dentry *blk_debugfs_root;
+
/* pers_list is a list of registered personalities protected
* by pers_lock.
* pers_lock does extra service to protect accesses to
@@ -5191,6 +5194,65 @@ md_attr_store(struct kobject *kobj, struct attribute *attr,
return rv;
}

+static int md_dbg_iostat_show(struct seq_file *m, void *data)
+{
+ struct mddev *mddev = m->private;
+ int active_bm_io = 0;
+
+ spin_lock(&mddev->lock);
+ if (mddev->bitmap)
+ active_bm_io = atomic_read(&mddev->bitmap->pending_writes);
+ spin_unlock(&mddev->lock);
+
+ seq_printf(m, "active_io %d\n",
+ atomic_read(&mddev->active_io));
+ seq_printf(m, "sb_wait %d pending_writes %d\n",
+ waitqueue_active(&mddev->sb_wait),
+ atomic_read(&mddev->pending_writes));
+ seq_printf(m, "recovery_active %d\n",
+ atomic_read(&mddev->recovery_active));
+ seq_printf(m, "bitmap pending_writes %d\n", active_bm_io);
+
+ return 0;
+}
+
+static int md_dbg_stat_show(struct seq_file *m, void *data)
+{
+ struct mddev *mddev = m->private;
+
+ seq_printf(m, "flags 0x%lx\n", mddev->flags);
+ seq_printf(m, "sb_flags 0x%lx\n", mddev->sb_flags);
+ seq_printf(m, "recovery 0x%lx\n", mddev->recovery);
+
+ return 0;
+}
+
+static const struct md_debugfs_file md_dbg_files[] = {
+ {.name = "iostat", .show = md_dbg_iostat_show},
+ {.name = "stat", .show = md_dbg_stat_show},
+ {},
+};
+
+static void md_unregister_debugfs(struct mddev *mddev)
+{
+ debugfs_remove_recursive(mddev->debugfs_dir);
+}
+
+static void md_register_debugfs(struct mddev *mddev)
+{
+ const char *name;
+ struct dentry *dir;
+
+ name = kobject_name(&disk_to_dev(mddev->gendisk)->kobj);
+ dir = debugfs_create_dir(name, blk_debugfs_root);
+ if (!IS_ERR_OR_NULL(dir)) {
+ md_debugfs_create_files(dir, mddev, md_dbg_files);
+ mddev->debugfs_dir = dir;
+ } else {
+ mddev->debugfs_dir = NULL;
+ }
+}
+
static void md_free(struct kobject *ko)
{
struct mddev *mddev = container_of(ko, struct mddev, kobj);
@@ -5227,6 +5289,7 @@ static void mddev_delayed_delete(struct work_struct *ws)
{
struct mddev *mddev = container_of(ws, struct mddev, del_work);

+ md_unregister_debugfs(mddev);
sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
kobject_del(&mddev->kobj);
kobject_put(&mddev->kobj);
@@ -5353,6 +5416,8 @@ static int md_alloc(dev_t dev, char *name)
if (mddev->kobj.sd &&
sysfs_create_group(&mddev->kobj, &md_bitmap_group))
pr_debug("pointless warning\n");
+
+ md_register_debugfs(mddev);
mutex_unlock(&mddev->open_mutex);
abort:
mutex_unlock(&disks_mutex);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 7c930c091193..e79ef2101c45 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -466,6 +466,7 @@ struct mddev {
unsigned int good_device_nr; /* good device num within cluster raid */

bool has_superblocks:1;
+ struct dentry *debugfs_dir;
};

enum recovery_flags {
--
2.22.0
\
 
 \ /
  Last update: 2019-07-02 15:24    [W:0.089 / U:7.304 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site