[PATCH v3] tools/xentop: Add VBD3 support to xentop

[Fouad Hilly <fouad.hilly@cloud.com>]

From: Pritha Srivastava <pritha.srivastava@citrix.com>

xl now knows how to drive tapdisk, so modify libxenstat to
understand vbd3 statistics.

Signed-off-by: Pritha Srivastava <pritha.srivastava@citrix.com>
Signed-off-by: Jorge Martin <jorge.martin@citrix.com>
Signed-off-by: Fouad Hilly <fouad.hilly@cloud.com>
---
CC: Wei Liu <wl@xen.org>
CC: Anthony PERARD <anthony.perard@citrix.com>
CC: Juergen Gross <jgross@suse.com>

v2:
- Fix order of SoB
- Fix Syntax
- Re-order free(path)

v3:
- Add const to char *vbd3_path
- Replace VBD3 type magic number with define
- Remove setting vbd.back_type
- Add comment with link to external interface
---
 tools/libs/stat/xenstat_linux.c | 65 ++++++++++++++++++++++++++++++++-
 tools/libs/stat/xenstat_priv.h  | 17 +++++++++
 tools/xentop/xentop.c           |  1 +
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/tools/libs/stat/xenstat_linux.c b/tools/libs/stat/xenstat_linux.c
index cbba54aa83ee..b60e3fdcab3e 100644
--- a/tools/libs/stat/xenstat_linux.c
+++ b/tools/libs/stat/xenstat_linux.c
@@ -35,6 +35,7 @@
 #include "xenstat_priv.h"
 
 #define SYSFS_VBD_PATH "/sys/bus/xen-backend/devices"
+#define XENSTAT_VBD_TYPE_VBD3 3
 
 struct priv_data {
 	FILE *procnetdev;
@@ -390,6 +391,38 @@ void xenstat_uninit_networks(xenstat_handle * handle)
 		fclose(priv->procnetdev);
 }
 
+static int read_attributes_vbd3(const char *vbd3_path, xenstat_vbd *vbd)
+{
+	FILE *fp;
+	struct vbd3_stats vbd3_stats;
+
+	fp = fopen(vbd3_path, "rb");
+
+	if (fp == NULL) {
+		return -1;
+	}
+
+	if (fread(&vbd3_stats, sizeof(struct vbd3_stats), 1, fp) != 1) {
+		fclose(fp);
+		return -1;
+	}
+
+	if (vbd3_stats.version != 1) {
+		fclose(fp);
+		return -1;
+	}
+
+	vbd->oo_reqs = vbd3_stats.oo_reqs;
+	vbd->rd_reqs = vbd3_stats.read_reqs_submitted;
+	vbd->rd_sects = vbd3_stats.read_sectors;
+	vbd->wr_reqs = vbd3_stats.write_reqs_submitted;
+	vbd->wr_sects = vbd3_stats.write_sectors;
+
+	fclose(fp);
+
+	return 0;
+}
+
 static int read_attributes_vbd(const char *vbd_directory, const char *what, char *ret, int cap)
 {
 	static char file_name[80];
@@ -438,7 +471,7 @@ int xenstat_collect_vbds(xenstat_node * node)
 		int ret;
 		char buf[256];
 
-		ret = sscanf(dp->d_name, "%3s-%u-%u", buf, &domid, &vbd.dev);
+		ret = sscanf(dp->d_name, "%255[^-]-%u-%u", buf, &domid, &vbd.dev);
 		if (ret != 3)
 			continue;
 		if (!(strstr(buf, "vbd")) && !(strstr(buf, "tap")))
@@ -448,6 +481,8 @@ int xenstat_collect_vbds(xenstat_node * node)
 			vbd.back_type = 1;
 		else if (strcmp(buf,"tap") == 0)
 			vbd.back_type = 2;
+		else if (strcmp(buf,"vbd3") == 0)
+			vbd.back_type = XENSTAT_VBD_TYPE_VBD3;
 		else
 			vbd.back_type = 0;
 
@@ -479,6 +514,34 @@ int xenstat_collect_vbds(xenstat_node * node)
 				vbd.error = 1;
 			}
 		}
+		else if (vbd.back_type == XENSTAT_VBD_TYPE_VBD3)
+		{
+			char *td3_pid;
+			char *path;
+
+			vbd.error = 0;
+
+			if (asprintf(&path, "/local/domain/0/backend/vbd3/%u/%u/kthread-pid", domid, vbd.dev) < 0)
+				continue;
+
+			td3_pid = xs_read(node->handle->xshandle, XBT_NULL, path, NULL);
+
+			free(path);
+
+			if (td3_pid == NULL)
+				continue;
+
+			if (asprintf(&path, "/dev/shm/td3-%s/vbd-%u-%u", td3_pid, domid, vbd.dev) < 0) {
+				free(td3_pid);
+				continue;
+			}
+
+			if (read_attributes_vbd3(path, &vbd) < 0)
+				vbd.error = 1;
+
+			free(td3_pid);
+			free(path);
+		}
 		else
 		{
 			vbd.error = 1;
diff --git a/tools/libs/stat/xenstat_priv.h b/tools/libs/stat/xenstat_priv.h
index 4eb44a8ebb84..51ff6862cf49 100644
--- a/tools/libs/stat/xenstat_priv.h
+++ b/tools/libs/stat/xenstat_priv.h
@@ -98,6 +98,23 @@ struct xenstat_vbd {
 	unsigned long long wr_sects;
 };
 
+/* Interface provided by https://github.com/xapi-project/blktap */
+struct vbd3_stats {
+	uint32_t version;
+	uint32_t __pad;
+	uint64_t oo_reqs;
+	uint64_t read_reqs_submitted;
+	uint64_t read_reqs_completed;
+	uint64_t read_sectors;
+	uint64_t read_total_ticks;
+	uint64_t write_reqs_submitted;
+	uint64_t write_reqs_completed;
+	uint64_t write_sectors;
+	uint64_t write_total_ticks;
+	uint64_t io_errors;
+	uint64_t flags;
+};
+
 extern int xenstat_collect_networks(xenstat_node * node);
 extern void xenstat_uninit_networks(xenstat_handle * handle);
 extern int xenstat_collect_vbds(xenstat_node * node);
diff --git a/tools/xentop/xentop.c b/tools/xentop/xentop.c
index 0a2fab7f15a3..f5a456fd4dfd 100644
--- a/tools/xentop/xentop.c
+++ b/tools/xentop/xentop.c
@@ -1124,6 +1124,7 @@ void do_vbd(xenstat_domain *domain)
 		"Unidentified",           /* number 0 */
 		"BlkBack",           /* number 1 */
 		"BlkTap",            /* number 2 */
+		"Tapdisk3"           /* number 3 */
 	};
 
 	num_vbds = xenstat_domain_num_vbds(domain);
-- 
2.42.0