drbd: debugfs: add basic hierarchy

Add new debugfs hierarchy /sys/kernel/debug/
  drbd/
    resources/
      $resource_name/connections/peer/$volume_number/
      $resource_name/volumes/$volume_number/
    minors/$minor_number -> ../resources/$resource_name/volumes/$volume_number/

Followup commits will populate this hierarchy with files containing
statistics, diagnostic information and some attribute data.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

5 files changed, 278 insertions, 5 deletions

diff --git a/drivers/block/drbd/Makefile b/drivers/block/drbd/Makefile
index 8b450338075e..4464e353c1e8 100644
--- a/drivers/block/drbd/Makefile
+++ b/drivers/block/drbd/Makefile
@@ -3,5 +3,6 @@ drbd-y += drbd_worker.o drbd_receiver.o drbd_req.o drbd_actlog.o
 drbd-y += drbd_main.o drbd_strings.o drbd_nl.o
 drbd-y += drbd_interval.o drbd_state.o
 drbd-y += drbd_nla.o
+drbd-$(CONFIG_DEBUG_FS) += drbd_debugfs.o
 
 obj-$(CONFIG_BLK_DEV_DRBD)     += drbd.o
diff --git a/drivers/block/drbd/drbd_debugfs.c b/drivers/block/drbd/drbd_debugfs.c
new file mode 100644
index 000000000000..9b120c3d9703
--- /dev/null
+++ b/drivers/block/drbd/drbd_debugfs.c
@@ -0,0 +1,191 @@
+#define pr_fmt(fmt) "drbd debugfs: " fmt
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/stat.h>
+#include <linux/list.h>
+
+#include "drbd_int.h"
+#include "drbd_req.h"
+#include "drbd_debugfs.h"
+
+static struct dentry *drbd_debugfs_root;
+static struct dentry *drbd_debugfs_resources;
+static struct dentry *drbd_debugfs_minors;
+
+void drbd_debugfs_resource_add(struct drbd_resource *resource)
+{
+        struct dentry *dentry;
+        if (!drbd_debugfs_resources)
+                return;
+
+        dentry = debugfs_create_dir(resource->name, drbd_debugfs_resources);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        resource->debugfs_res = dentry;
+
+        dentry = debugfs_create_dir("volumes", resource->debugfs_res);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        resource->debugfs_res_volumes = dentry;
+
+        dentry = debugfs_create_dir("connections", resource->debugfs_res);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        resource->debugfs_res_connections = dentry;
+
+        return;
+
+fail:
+        drbd_debugfs_resource_cleanup(resource);
+        drbd_err(resource, "failed to create debugfs dentry\n");
+}
+
+static void drbd_debugfs_remove(struct dentry **dp)
+{
+        debugfs_remove(*dp);
+        *dp = NULL;
+}
+
+void drbd_debugfs_resource_cleanup(struct drbd_resource *resource)
+{
+        /* it is ok to call debugfs_remove(NULL) */
+        drbd_debugfs_remove(&resource->debugfs_res_in_flight_summary);
+        drbd_debugfs_remove(&resource->debugfs_res_connections);
+        drbd_debugfs_remove(&resource->debugfs_res_volumes);
+        drbd_debugfs_remove(&resource->debugfs_res);
+}
+
+void drbd_debugfs_connection_add(struct drbd_connection *connection)
+{
+        struct dentry *conns_dir = connection->resource->debugfs_res_connections;
+        struct dentry *dentry;
+        if (!conns_dir)
+                return;
+
+        /* Once we enable mutliple peers,
+         * these connections will have descriptive names.
+         * For now, it is just the one connection to the (only) "peer". */
+        dentry = debugfs_create_dir("peer", conns_dir);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        connection->debugfs_conn = dentry;
+        return;
+
+fail:
+        drbd_debugfs_connection_cleanup(connection);
+        drbd_err(connection, "failed to create debugfs dentry\n");
+}
+
+void drbd_debugfs_connection_cleanup(struct drbd_connection *connection)
+{
+        drbd_debugfs_remove(&connection->debugfs_conn_callback_history);
+        drbd_debugfs_remove(&connection->debugfs_conn_oldest_requests);
+        drbd_debugfs_remove(&connection->debugfs_conn);
+}
+
+void drbd_debugfs_device_add(struct drbd_device *device)
+{
+        struct dentry *vols_dir = device->resource->debugfs_res_volumes;
+        char minor_buf[8]; /* MINORMASK, MINORBITS == 20; */
+        char vnr_buf[8];   /* volume number vnr is even 16 bit only; */
+        char *slink_name = NULL;
+
+        struct dentry *dentry;
+        if (!vols_dir || !drbd_debugfs_minors)
+                return;
+
+        snprintf(vnr_buf, sizeof(vnr_buf), "%u", device->vnr);
+        dentry = debugfs_create_dir(vnr_buf, vols_dir);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        device->debugfs_vol = dentry;
+
+        snprintf(minor_buf, sizeof(minor_buf), "%u", device->minor);
+        slink_name = kasprintf(GFP_KERNEL, "../resources/%s/volumes/%u",
+                        device->resource->name, device->vnr);
+        if (!slink_name)
+                goto fail;
+        dentry = debugfs_create_symlink(minor_buf, drbd_debugfs_minors, slink_name);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        device->debugfs_minor = dentry;
+        kfree(slink_name);
+
+fail:
+        drbd_debugfs_device_cleanup(device);
+        drbd_err(device, "failed to create debugfs entries\n");
+}
+
+void drbd_debugfs_device_cleanup(struct drbd_device *device)
+{
+        drbd_debugfs_remove(&device->debugfs_minor);
+        drbd_debugfs_remove(&device->debugfs_vol_oldest_requests);
+        drbd_debugfs_remove(&device->debugfs_vol_act_log_extents);
+        drbd_debugfs_remove(&device->debugfs_vol_resync_extents);
+        drbd_debugfs_remove(&device->debugfs_vol_data_gen_id);
+        drbd_debugfs_remove(&device->debugfs_vol);
+}
+
+void drbd_debugfs_peer_device_add(struct drbd_peer_device *peer_device)
+{
+        struct dentry *conn_dir = peer_device->connection->debugfs_conn;
+        struct dentry *dentry;
+        char vnr_buf[8];
+
+        if (!conn_dir)
+                return;
+
+        snprintf(vnr_buf, sizeof(vnr_buf), "%u", peer_device->device->vnr);
+        dentry = debugfs_create_dir(vnr_buf, conn_dir);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        peer_device->debugfs_peer_dev = dentry;
+        return;
+
+fail:
+        drbd_debugfs_peer_device_cleanup(peer_device);
+        drbd_err(peer_device, "failed to create debugfs entries\n");
+}
+
+void drbd_debugfs_peer_device_cleanup(struct drbd_peer_device *peer_device)
+{
+        drbd_debugfs_remove(&peer_device->debugfs_peer_dev);
+}
+
+/* not __exit, may be indirectly called
+ * from the module-load-failure path as well. */
+void drbd_debugfs_cleanup(void)
+{
+        drbd_debugfs_remove(&drbd_debugfs_resources);
+        drbd_debugfs_remove(&drbd_debugfs_minors);
+        drbd_debugfs_remove(&drbd_debugfs_root);
+}
+
+int __init drbd_debugfs_init(void)
+{
+        struct dentry *dentry;
+
+        dentry = debugfs_create_dir("drbd", NULL);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        drbd_debugfs_root = dentry;
+
+        dentry = debugfs_create_dir("resources", drbd_debugfs_root);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        drbd_debugfs_resources = dentry;
+
+        dentry = debugfs_create_dir("minors", drbd_debugfs_root);
+        if (IS_ERR_OR_NULL(dentry))
+                goto fail;
+        drbd_debugfs_minors = dentry;
+        return 0;
+
+fail:
+        drbd_debugfs_cleanup();
+        if (dentry)
+                return PTR_ERR(dentry);
+        else
+                return -EINVAL;
+}
diff --git a/drivers/block/drbd/drbd_debugfs.h b/drivers/block/drbd/drbd_debugfs.h
new file mode 100644
index 000000000000..8bee21340dce
--- /dev/null
+++ b/drivers/block/drbd/drbd_debugfs.h
@@ -0,0 +1,39 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+
+#include "drbd_int.h"
+
+#ifdef CONFIG_DEBUG_FS
+int __init drbd_debugfs_init(void);
+void drbd_debugfs_cleanup(void);
+
+void drbd_debugfs_resource_add(struct drbd_resource *resource);
+void drbd_debugfs_resource_cleanup(struct drbd_resource *resource);
+
+void drbd_debugfs_connection_add(struct drbd_connection *connection);
+void drbd_debugfs_connection_cleanup(struct drbd_connection *connection);
+
+void drbd_debugfs_device_add(struct drbd_device *device);
+void drbd_debugfs_device_cleanup(struct drbd_device *device);
+
+void drbd_debugfs_peer_device_add(struct drbd_peer_device *peer_device);
+void drbd_debugfs_peer_device_cleanup(struct drbd_peer_device *peer_device);
+#else
+
+static inline int __init drbd_debugfs_init(void) { return -ENODEV; }
+static inline void drbd_debugfs_cleanup(void) { }
+
+static inline void drbd_debugfs_resource_add(struct drbd_resource *resource) { }
+static inline void drbd_debugfs_resource_cleanup(struct drbd_resource *resource) { }
+
+static inline void drbd_debugfs_connection_add(struct drbd_connection *connection) { }
+static inline void drbd_debugfs_connection_cleanup(struct drbd_connection *connection) { }
+
+static inline void drbd_debugfs_device_add(struct drbd_device *device) { }
+static inline void drbd_debugfs_device_cleanup(struct drbd_device *device) { }
+
+static inline void drbd_debugfs_peer_device_add(struct drbd_peer_device *peer_device) { }
+static inline void drbd_debugfs_peer_device_cleanup(struct drbd_peer_device *peer_device) { }
+
+#endif
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 40c816ce8d75..20f2b38e97b9 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -670,6 +670,12 @@ enum {
 
 struct drbd_resource {
         char *name;
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debugfs_res;
+        struct dentry *debugfs_res_volumes;
+        struct dentry *debugfs_res_connections;
+        struct dentry *debugfs_res_in_flight_summary;
+#endif
         struct kref kref;
         struct idr devices;             /* volume number to device mapping */
         struct list_head connections;
@@ -691,6 +697,11 @@ struct drbd_resource {
 struct drbd_connection {
         struct list_head connections;
         struct drbd_resource *resource;
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debugfs_conn;
+        struct dentry *debugfs_conn_callback_history;
+        struct dentry *debugfs_conn_oldest_requests;
+#endif
         struct kref kref;
         struct idr peer_devices;        /* volume number to peer device mapping */
         enum drbd_conns cstate;         /* Only C_STANDALONE to C_WF_REPORT_PARAMS */
@@ -772,13 +783,29 @@ struct drbd_peer_device {
         struct list_head peer_devices;
         struct drbd_device *device;
         struct drbd_connection *connection;
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debugfs_peer_dev;
+#endif
 };
 
 struct drbd_device {
         struct drbd_resource *resource;
         struct list_head peer_devices;
         struct list_head pending_bitmap_io;
-        int vnr;                        /* volume number within the connection */
+
+        unsigned long flush_jif;
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debugfs_minor;
+        struct dentry *debugfs_vol;
+        struct dentry *debugfs_vol_oldest_requests;
+        struct dentry *debugfs_vol_act_log_extents;
+        struct dentry *debugfs_vol_resync_extents;
+        struct dentry *debugfs_vol_data_gen_id;
+#endif
+
+        unsigned int vnr;       /* volume number within the connection */
+        unsigned int minor;     /* device minor number */
+
         struct kref kref;
 
         /* things that are stored as / read from meta data on disk */
@@ -895,7 +922,6 @@ struct drbd_device {
         atomic_t packet_seq;
         unsigned int peer_seq;
         spinlock_t peer_seq_lock;
-        unsigned int minor;
         unsigned long comm_bm_set; /* communicated number of set bits. */
         struct bm_io_work bm_io_work;
         u64 ed_uuid; /* UUID of the exposed data */
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 922d631c10b3..01de57ec0110 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -57,8 +57,8 @@
 #include "drbd_int.h"
 #include "drbd_protocol.h"
 #include "drbd_req.h" /* only for _req_mod in tl_release and tl_clear */
-
 #include "drbd_vli.h"
+#include "drbd_debugfs.h"
 
 static DEFINE_MUTEX(drbd_main_mutex);
 static int drbd_open(struct block_device *bdev, fmode_t mode);
@@ -2308,8 +2308,10 @@ void drbd_free_resource(struct drbd_resource *resource)
 
         for_each_connection_safe(connection, tmp, resource) {
                 list_del(&connection->connections);
+                drbd_debugfs_connection_cleanup(connection);
                 kref_put(&connection->kref, drbd_destroy_connection);
         }
+        drbd_debugfs_resource_cleanup(resource);
         kref_put(&resource->kref, drbd_destroy_resource);
 }
 
@@ -2334,6 +2336,7 @@ static void drbd_cleanup(void)
                 destroy_workqueue(retry.wq);
 
         drbd_genl_unregister();
+        drbd_debugfs_cleanup();
 
         idr_for_each_entry(&drbd_devices, device, i)
                 drbd_delete_device(device);
@@ -2583,6 +2586,7 @@ struct drbd_resource *drbd_create_resource(const char *name)
         mutex_init(&resource->conf_update);
         mutex_init(&resource->adm_mutex);
         spin_lock_init(&resource->req_lock);
+        drbd_debugfs_resource_add(resource);
         return resource;
 
 fail_free_name:
@@ -2593,7 +2597,7 @@ fail:
         return NULL;
 }
 
-/* caller must be under genl_lock() */
+/* caller must be under adm_mutex */
 struct drbd_connection *conn_create(const char *name, struct res_opts *res_opts)
 {
         struct drbd_resource *resource;
@@ -2651,6 +2655,7 @@ struct drbd_connection *conn_create(const char *name, struct res_opts *res_opts)
 
         kref_get(&resource->kref);
         list_add_tail_rcu(&connection->connections, &resource->connections);
+        drbd_debugfs_connection_add(connection);
         return connection;
 
 fail_resource:
@@ -2829,7 +2834,10 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
                 for_each_peer_device(peer_device, device)
                         drbd_connected(peer_device);
         }
-
+        /* move to create_peer_device() */
+        for_each_peer_device(peer_device, device)
+                drbd_debugfs_peer_device_add(peer_device);
+        drbd_debugfs_device_add(device);
         return NO_ERROR;
 
 out_idr_remove_vol:
@@ -2868,8 +2876,13 @@ void drbd_delete_device(struct drbd_device *device)
 {
         struct drbd_resource *resource = device->resource;
         struct drbd_connection *connection;
+        struct drbd_peer_device *peer_device;
         int refs = 3;
 
+        /* move to free_peer_device() */
+        for_each_peer_device(peer_device, device)
+                drbd_debugfs_peer_device_cleanup(peer_device);
+        drbd_debugfs_device_cleanup(device);
         for_each_connection(connection, resource) {
                 idr_remove(&connection->peer_devices, device->vnr);
                 refs++;
@@ -2938,6 +2951,9 @@ static int __init drbd_init(void)
         spin_lock_init(&retry.lock);
         INIT_LIST_HEAD(&retry.writes);
 
+        if (drbd_debugfs_init())
+                pr_notice("failed to initialize debugfs -- will not be available\n");
+
         pr_info("initialized. "
                "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
                API_VERSION, PRO_VERSION_MIN, PRO_VERSION_MAX);