[BLKBACK] Output statistics to sysfs.

The location is 'statistics' directory under each VBD directory, for
example, /sys/devices/xen-backend/vbd-x-xxxx/statistics.

The 'statistics' directory includes the following three statistical
information:
  oo_req
       is the number of requests held up due to full pipeline.
  rd_req
       is the number of processed READ requests.
  wr_req
       is the number of processed WRITE requests.

Signed-off-by: Satoshi UCHIDA <s-uchida@ap.jp.nec.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
index 5ee3a46982b5025b612f12d2ed7232a7d373e807..406adf10007e5da8262f04fc151160bc2ad54d6f 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c
@@ -43,7 +43,6 @@ static int connect_ring(struct backend_info *);
 static void backend_changed(struct xenbus_watch *, const char **,
                            unsigned int);
 
-
 static void update_blkif_status(blkif_t *blkif)
 { 
        int err;
@@ -73,6 +72,70 @@ static void update_blkif_status(blkif_t *blkif)
 }
 
 
+/****************************************************************
+ *  sysfs interface for VBD I/O requests
+ */
+
+#ifdef CONFIG_SYSFS
+
+#define VBD_SHOW(name, format, args...)                                        \
+       static ssize_t show_##name(struct device *_dev,                 \
+                                  struct device_attribute *attr,       \
+                                  char *buf)                           \
+       {                                                               \
+               struct xenbus_device *dev = to_xenbus_device(_dev);     \
+               struct backend_info *be = dev->dev.driver_data;         \
+                                                                       \
+               return sprintf(buf, format, ##args);                    \
+       }                                                               \
+       DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
+
+VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req);
+VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req);
+VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req);
+
+static struct attribute *vbdstat_attrs[] = {
+       &dev_attr_oo_req.attr,
+       &dev_attr_rd_req.attr,
+       &dev_attr_wr_req.attr,
+       NULL
+};
+
+static struct attribute_group vbdstat_group = {
+       .name = "statistics",
+       .attrs = vbdstat_attrs,
+};
+
+int xenvbd_sysfs_addif(struct xenbus_device *dev)
+{
+       int error = 0;
+       
+       error = sysfs_create_group(&dev->dev.kobj,
+                                  &vbdstat_group);
+       if (error)
+               goto fail;
+       
+       return 0;
+       
+fail:
+       sysfs_remove_group(&dev->dev.kobj,
+                          &vbdstat_group);
+       return error;
+}
+
+void xenvbd_sysfs_delif(struct xenbus_device *dev)
+{
+       sysfs_remove_group(&dev->dev.kobj,
+                          &vbdstat_group);
+}
+
+#else
+
+#define xenvbd_sysfs_addif(dev) (0)
+#define xenvbd_sysfs_delif(dev) ((void)0)
+
+#endif /* CONFIG_SYSFS */
+
 static ssize_t show_physical_device(struct device *_dev,
                                    struct device_attribute *attr, char *buf)
 {
@@ -115,6 +178,7 @@ static int blkback_remove(struct xenbus_device *dev)
 
        device_remove_file(&dev->dev, &dev_attr_physical_device);
        device_remove_file(&dev->dev, &dev_attr_mode);
+       xenvbd_sysfs_delif(dev);
 
        kfree(be);
        dev->dev.driver_data = NULL;
@@ -237,6 +301,7 @@ static void backend_changed(struct xenbus_watch *watch,
 
                device_create_file(&dev->dev, &dev_attr_physical_device);
                device_create_file(&dev->dev, &dev_attr_mode);
+               xenvbd_sysfs_addif(dev);
 
                /* We're potentially connected now */
                update_blkif_status(be->blkif);