xen/blkback: make st_ statistics per ring

Make st_* statistics per ring and the VBD sysfs would iterate over all the
rings.

Note: xenvbd_sysfs_delif() is called in xen_blkbk_remove() before all rings
are torn down, so it's safe.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
v2: Aligned the variables on the same column.

3 files changed, 61 insertions, 38 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 99b479f330af..148930c8c121 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -587,20 +587,18 @@ irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
 
 static void print_stats(struct xen_blkif_ring *ring)
 {
-        struct xen_blkif *blkif = ring->blkif;
-
         pr_info("(%s): oo %3llu  |  rd %4llu  |  wr %4llu  |  f %4llu"
                  "  |  ds %4llu | pg: %4u/%4d\n",
-                 current->comm, blkif->st_oo_req,
-                 blkif->st_rd_req, blkif->st_wr_req,
-                 blkif->st_f_req, blkif->st_ds_req,
+                 current->comm, ring->st_oo_req,
+                 ring->st_rd_req, ring->st_wr_req,
+                 ring->st_f_req, ring->st_ds_req,
                  ring->persistent_gnt_c,
                  xen_blkif_max_pgrants);
-        blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
-        blkif->st_rd_req = 0;
-        blkif->st_wr_req = 0;
-        blkif->st_oo_req = 0;
-        blkif->st_ds_req = 0;
+        ring->st_print = jiffies + msecs_to_jiffies(10 * 1000);
+        ring->st_rd_req = 0;
+        ring->st_wr_req = 0;
+        ring->st_oo_req = 0;
+        ring->st_ds_req = 0;
 }
 
 int xen_blkif_schedule(void *arg)
@@ -656,7 +654,7 @@ purge_gnt_list:
                 /* Shrink if we have more than xen_blkif_max_buffer_pages */
                 shrink_free_pagepool(ring, xen_blkif_max_buffer_pages);
 
-                if (log_stats && time_after(jiffies, ring->blkif->st_print))
+                if (log_stats && time_after(jiffies, ring->st_print))
                         print_stats(ring);
         }
 
@@ -1018,7 +1016,7 @@ static int dispatch_discard_io(struct xen_blkif_ring *ring,
                         preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
                 goto fail_response;
         }
-        blkif->st_ds_req++;
+        ring->st_ds_req++;
 
         secure = (blkif->vbd.discard_secure &&
                  (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
@@ -1145,7 +1143,7 @@ __do_block_io_op(struct xen_blkif_ring *ring)
 
                 pending_req = alloc_req(ring);
                 if (NULL == pending_req) {
-                        ring->blkif->st_oo_req++;
+                        ring->st_oo_req++;
                         more_to_do = 1;
                         break;
                 }
@@ -1243,17 +1241,17 @@ static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
 
         switch (req_operation) {
         case BLKIF_OP_READ:
-                ring->blkif->st_rd_req++;
+                ring->st_rd_req++;
                 operation = READ;
                 break;
         case BLKIF_OP_WRITE:
-                ring->blkif->st_wr_req++;
+                ring->st_wr_req++;
                 operation = WRITE_ODIRECT;
                 break;
         case BLKIF_OP_WRITE_BARRIER:
                 drain = true;
         case BLKIF_OP_FLUSH_DISKCACHE:
-                ring->blkif->st_f_req++;
+                ring->st_f_req++;
                 operation = WRITE_FLUSH;
                 break;
         default:
@@ -1395,9 +1393,9 @@ static int dispatch_rw_block_io(struct xen_blkif_ring *ring,
         blk_finish_plug(&plug);
 
         if (operation == READ)
-                ring->blkif->st_rd_sect += preq.nr_sects;
+                ring->st_rd_sect += preq.nr_sects;
         else if (operation & WRITE)
-                ring->blkif->st_wr_sect += preq.nr_sects;
+                ring->st_wr_sect += preq.nr_sects;
 
         return 0;
 
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 3c244ecf22a4..b27c5ba15600 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -298,6 +298,16 @@ struct xen_blkif_ring {
         atomic_t                persistent_gnt_in_use;
         unsigned long           next_lru;
 
+        /* Statistics. */
+        unsigned long           st_print;
+        unsigned long long      st_rd_req;
+        unsigned long long      st_wr_req;
+        unsigned long long      st_oo_req;
+        unsigned long long      st_f_req;
+        unsigned long long      st_ds_req;
+        unsigned long long      st_rd_sect;
+        unsigned long long      st_wr_sect;
+
         /* Used by the kworker that offload work from the persistent purge. */
         struct list_head        persistent_purge_list;
         struct work_struct      persistent_purge_work;
@@ -328,16 +338,6 @@ struct xen_blkif {
         struct completion       drain_complete;
         atomic_t                drain;
 
-        /* statistics */
-        unsigned long           st_print;
-        unsigned long long                      st_rd_req;
-        unsigned long long                      st_wr_req;
-        unsigned long long                      st_oo_req;
-        unsigned long long                      st_f_req;
-        unsigned long long                      st_ds_req;
-        unsigned long long                      st_rd_sect;
-        unsigned long long                      st_wr_sect;
-
         struct work_struct      free_work;
         unsigned int            nr_ring_pages;
         /* All rings for this device. */
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index c92b35882720..44396b8a0cb2 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -159,6 +159,7 @@ static int xen_blkif_alloc_rings(struct xen_blkif *blkif)
                 init_waitqueue_head(&ring->pending_free_wq);
                 init_waitqueue_head(&ring->shutdown_wq);
                 ring->blkif = blkif;
+                ring->st_print = jiffies;
                 xen_blkif_get(blkif);
         }
 
@@ -179,7 +180,6 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
         atomic_set(&blkif->refcnt, 1);
         init_completion(&blkif->drain_complete);
         INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
-        blkif->st_print = jiffies;
 
         return blkif;
 }
@@ -329,25 +329,38 @@ int __init xen_blkif_interface_init(void)
  *  sysfs interface for VBD I/O requests
  */
 
-#define VBD_SHOW(name, format, args...)                                 \
+#define VBD_SHOW_ALLRING(name, format)                                  \
         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_get_drvdata(&dev->dev);   \
+                struct xen_blkif *blkif = be->blkif;                    \
+                unsigned int i;                                         \
+                unsigned long long result = 0;                          \
                                                                         \
-                return sprintf(buf, format, ##args);                    \
+                if (!blkif->rings)                              \
+                        goto out;                                       \
+                                                                        \
+                for (i = 0; i < blkif->nr_rings; i++) {         \
+                        struct xen_blkif_ring *ring = &blkif->rings[i]; \
+                                                                        \
+                        result += ring->st_##name;                      \
+                }                                                       \
+                                                                        \
+out:                                                                    \
+                return sprintf(buf, format, result);                    \
         }                                                               \
         static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
 
-VBD_SHOW(oo_req,  "%llu\n", be->blkif->st_oo_req);
-VBD_SHOW(rd_req,  "%llu\n", be->blkif->st_rd_req);
-VBD_SHOW(wr_req,  "%llu\n", be->blkif->st_wr_req);
-VBD_SHOW(f_req,  "%llu\n", be->blkif->st_f_req);
-VBD_SHOW(ds_req,  "%llu\n", be->blkif->st_ds_req);
-VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect);
-VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect);
+VBD_SHOW_ALLRING(oo_req,  "%llu\n");
+VBD_SHOW_ALLRING(rd_req,  "%llu\n");
+VBD_SHOW_ALLRING(wr_req,  "%llu\n");
+VBD_SHOW_ALLRING(f_req,  "%llu\n");
+VBD_SHOW_ALLRING(ds_req,  "%llu\n");
+VBD_SHOW_ALLRING(rd_sect, "%llu\n");
+VBD_SHOW_ALLRING(wr_sect, "%llu\n");
 
 static struct attribute *xen_vbdstat_attrs[] = {
         &dev_attr_oo_req.attr,
@@ -365,6 +378,18 @@ static struct attribute_group xen_vbdstat_group = {
         .attrs = xen_vbdstat_attrs,
 };
 
+#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_get_drvdata(&dev->dev);   \
+                                                                        \
+                return sprintf(buf, format, ##args);                    \
+        }                                                               \
+        static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
+
 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
 VBD_SHOW(mode, "%s\n", be->mode);