rbd: normalize dout() calls

Add dout() calls to facilitate tracing of image and object requests.
Change a few existing calls so they use __func__ rather than the
hard-coded function name.  Have calls always add ":" after the name
of the function, and prefix pointer values with a consistent tag
indicating what it represents.  (Note that there remain some older
dout() calls that are left untouched by this patch.)

Issue a warning if rbd_osd_write_callback() ever gets a short write.

This resolves:
    http://tracker.ceph.com/issues/4235

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

drivers/block/rbd.c

@@ -443,7 +443,7 @@ static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts)
 	struct rbd_client *rbdc;
 	int ret = -ENOMEM;
 
-	dout("rbd_client_create\n");
+	dout("%s:\n", __func__);
 	rbdc = kmalloc(sizeof(struct rbd_client), GFP_KERNEL);
 	if (!rbdc)
 		goto out_opt;
@@ -467,8 +467,8 @@ static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts)
 	spin_unlock(&rbd_client_list_lock);
 
 	mutex_unlock(&ctl_mutex);
+	dout("%s: rbdc %p\n", __func__, rbdc);
 
-	dout("rbd_client_create created %p\n", rbdc);
 	return rbdc;
 
 out_err:
@@ -479,6 +479,8 @@ out_mutex:
 out_opt:
 	if (ceph_opts)
 		ceph_destroy_options(ceph_opts);
+	dout("%s: error %d\n", __func__, ret);
+
 	return ERR_PTR(ret);
 }
 
@@ -605,7 +607,7 @@ static void rbd_client_release(struct kref *kref)
 {
 	struct rbd_client *rbdc = container_of(kref, struct rbd_client, kref);
 
-	dout("rbd_release_client %p\n", rbdc);
+	dout("%s: rbdc %p\n", __func__, rbdc);
 	spin_lock(&rbd_client_list_lock);
 	list_del(&rbdc->node);
 	spin_unlock(&rbd_client_list_lock);
@@ -1064,6 +1066,8 @@ out_err:
 
 static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
 {
+	dout("%s: obj %p (was %d)\n", __func__, obj_request,
+		atomic_read(&obj_request->kref.refcount));
 	kref_get(&obj_request->kref);
 }
 
@@ -1071,11 +1075,15 @@ static void rbd_obj_request_destroy(struct kref *kref);
 static void rbd_obj_request_put(struct rbd_obj_request *obj_request)
 {
 	rbd_assert(obj_request != NULL);
+	dout("%s: obj %p (was %d)\n", __func__, obj_request,
+		atomic_read(&obj_request->kref.refcount));
 	kref_put(&obj_request->kref, rbd_obj_request_destroy);
 }
 
 static void rbd_img_request_get(struct rbd_img_request *img_request)
 {
+	dout("%s: img %p (was %d)\n", __func__, img_request,
+		atomic_read(&img_request->kref.refcount));
 	kref_get(&img_request->kref);
 }
 
@@ -1083,6 +1091,8 @@ static void rbd_img_request_destroy(struct kref *kref);
 static void rbd_img_request_put(struct rbd_img_request *img_request)
 {
 	rbd_assert(img_request != NULL);
+	dout("%s: img %p (was %d)\n", __func__, img_request,
+		atomic_read(&img_request->kref.refcount));
 	kref_put(&img_request->kref, rbd_img_request_destroy);
 }
 
@@ -1097,6 +1107,8 @@ static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
 	rbd_assert(obj_request->which != BAD_WHICH);
 	img_request->obj_request_count++;
 	list_add_tail(&obj_request->links, &img_request->obj_requests);
+	dout("%s: img %p obj %p w=%u\n", __func__, img_request, obj_request,
+		obj_request->which);
 }
 
 static inline void rbd_img_obj_request_del(struct rbd_img_request *img_request,
@@ -1104,6 +1116,8 @@ static inline void rbd_img_obj_request_del(struct rbd_img_request *img_request,
 {
 	rbd_assert(obj_request->which != BAD_WHICH);
 
+	dout("%s: img %p obj %p w=%u\n", __func__, img_request, obj_request,
+		obj_request->which);
 	list_del(&obj_request->links);
 	rbd_assert(img_request->obj_request_count > 0);
 	img_request->obj_request_count--;
@@ -1200,11 +1214,14 @@ static void rbd_osd_req_op_destroy(struct ceph_osd_req_op *op)
 static int rbd_obj_request_submit(struct ceph_osd_client *osdc,
 				struct rbd_obj_request *obj_request)
 {
+	dout("%s: osdc %p obj %p\n", __func__, osdc, obj_request);
+
 	return ceph_osdc_start_request(osdc, obj_request->osd_req, false);
 }
 
 static void rbd_img_request_complete(struct rbd_img_request *img_request)
 {
+	dout("%s: img %p\n", __func__, img_request);
 	if (img_request->callback)
 		img_request->callback(img_request);
 	else
@@ -1215,6 +1232,8 @@ static void rbd_img_request_complete(struct rbd_img_request *img_request)
 
 static int rbd_obj_request_wait(struct rbd_obj_request *obj_request)
 {
+	dout("%s: obj %p\n", __func__, obj_request);
+
 	return wait_for_completion_interruptible(&obj_request->completion);
 }
 
@@ -1248,11 +1267,14 @@ static bool obj_request_done_test(struct rbd_obj_request *obj_request)
 static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request,
 				struct ceph_osd_op *op)
 {
+	dout("%s: obj %p\n", __func__, obj_request);
 	obj_request_done_set(obj_request);
 }
 
 static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
 {
+	dout("%s: obj %p cb %p\n", __func__, obj_request,
+		obj_request->callback);
 	if (obj_request->callback)
 		obj_request->callback(obj_request);
 	else
@@ -1270,6 +1292,8 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request,
 	 */
 	xferred = le64_to_cpu(op->extent.length);
 	rbd_assert(xferred < (u64) UINT_MAX);
+	dout("%s: obj %p result %d %llu/%llu\n", __func__, obj_request,
+		obj_request->result, xferred, obj_request->length);
 	if (obj_request->result == (s32) -ENOENT) {
 		zero_bio_chain(obj_request->bio_list, 0);
 		obj_request->result = 0;
@@ -1284,7 +1308,22 @@ static void rbd_osd_read_callback(struct rbd_obj_request *obj_request,
 static void rbd_osd_write_callback(struct rbd_obj_request *obj_request,
 				struct ceph_osd_op *op)
 {
+
 	obj_request->xferred = le64_to_cpu(op->extent.length);
+	dout("%s: obj %p result %d %llu/%llu\n", __func__, obj_request,
+		obj_request->result, obj_request->xferred, obj_request->length);
+
+	/* A short write really shouldn't occur.  Warn if we see one */
+
+	if (obj_request->xferred != obj_request->length) {
+		struct rbd_img_request *img_request = obj_request->img_request;
+		struct rbd_device *rbd_dev;
+
+		rbd_dev = img_request ? img_request->rbd_dev : NULL;
+		rbd_warn(rbd_dev, "wrote %llu want %llu\n",
+			obj_request->xferred, obj_request->length);
+	}
+
 	obj_request_done_set(obj_request);
 }
 
@@ -1295,6 +1334,7 @@ static void rbd_osd_write_callback(struct rbd_obj_request *obj_request,
 static void rbd_osd_stat_callback(struct rbd_obj_request *obj_request,
 				struct ceph_osd_op *op)
 {
+	dout("%s: obj %p\n", __func__, obj_request);
 	obj_request_done_set(obj_request);
 }
 
@@ -1307,6 +1347,7 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 	u32 num_ops;
 	u16 opcode;
 
+	dout("%s: osd_req %p msg %p\n", __func__, osd_req, msg);
 	rbd_assert(osd_req == obj_request->osd_req);
 	rbd_assert(!!obj_request->img_request ^
 				(obj_request->which == BAD_WHICH));
@@ -1453,6 +1494,9 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
 	init_completion(&obj_request->completion);
 	kref_init(&obj_request->kref);
 
+	dout("%s: \"%s\" %llu/%llu %d -> obj %p\n", __func__, object_name,
+		offset, length, (int)type, obj_request);
+
 	return obj_request;
 }
 
@@ -1462,6 +1506,8 @@ static void rbd_obj_request_destroy(struct kref *kref)
 
 	obj_request = container_of(kref, struct rbd_obj_request, kref);
 
+	dout("%s: obj %p\n", __func__, obj_request);
+
 	rbd_assert(obj_request->img_request == NULL);
 	rbd_assert(obj_request->which == BAD_WHICH);
 
@@ -1531,6 +1577,10 @@ struct rbd_img_request *rbd_img_request_create(struct rbd_device *rbd_dev,
 	rbd_img_request_get(img_request);	/* Avoid a warning */
 	rbd_img_request_put(img_request);	/* TEMPORARY */
 
+	dout("%s: rbd_dev %p %s %llu/%llu -> img %p\n", __func__, rbd_dev,
+		write_request ? "write" : "read", offset, length,
+		img_request);
+
 	return img_request;
 }
 
@@ -1542,6 +1592,8 @@ static void rbd_img_request_destroy(struct kref *kref)
 
 	img_request = container_of(kref, struct rbd_img_request, kref);
 
+	dout("%s: img %p\n", __func__, img_request);
+
 	for_each_obj_request_safe(img_request, obj_request, next_obj_request)
 		rbd_img_obj_request_del(img_request, obj_request);
 	rbd_assert(img_request->obj_request_count == 0);
@@ -1563,6 +1615,8 @@ static int rbd_img_request_fill_bio(struct rbd_img_request *img_request,
 	u64 resid;
 	u16 opcode;
 
+	dout("%s: img %p bio %p\n", __func__, img_request, bio_list);
+
 	opcode = img_request->write_request ? CEPH_OSD_OP_WRITE
 					      : CEPH_OSD_OP_READ;
 	bio_offset = 0;
@@ -1638,6 +1692,7 @@ static void rbd_img_obj_callback(struct rbd_obj_request *obj_request)
 
 	img_request = obj_request->img_request;
 
+	dout("%s: img %p obj %p\n", __func__, img_request, obj_request);
 	rbd_assert(img_request != NULL);
 	rbd_assert(img_request->rq != NULL);
 	rbd_assert(img_request->obj_request_count > 0);
@@ -1685,6 +1740,7 @@ static int rbd_img_request_submit(struct rbd_img_request *img_request)
 	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
 	struct rbd_obj_request *obj_request;
 
+	dout("%s: img %p\n", __func__, img_request);
 	for_each_obj_request(img_request, obj_request) {
 		int ret;
 
@@ -1745,7 +1801,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 	if (!rbd_dev)
 		return;
 
-	dout("rbd_watch_cb %s notify_id=%llu opcode=%u\n",
+	dout("%s: \"%s\" notify_id %llu opcode %u\n", __func__,
 		rbd_dev->header_name, (unsigned long long) notify_id,
 		(unsigned int) opcode);
 	rc = rbd_dev_refresh(rbd_dev, &hver);
@@ -3371,7 +3427,7 @@ static int rbd_dev_snaps_register(struct rbd_device *rbd_dev)
 	struct rbd_snap *snap;
 	int ret = 0;
 
-	dout("%s called\n", __func__);
+	dout("%s:\n", __func__);
 	if (WARN_ON(!device_is_registered(&rbd_dev->dev)))
 		return -EIO;