rbd: implement watch/unwatch with new code
Implement a new function to set up or tear down a watch event
for an mapped rbd image header using the new request code.
Create a new object request type "nodata" to handle this. And
define rbd_osd_trivial_callback() which simply marks a request done.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 5e7110a..60b6851 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -170,7 +170,9 @@
struct rbd_obj_request;
typedef void (*rbd_obj_callback_t)(struct rbd_obj_request *);
-enum obj_request_type { OBJ_REQUEST_BIO, OBJ_REQUEST_PAGES };
+enum obj_request_type {
+ OBJ_REQUEST_NODATA, OBJ_REQUEST_BIO, OBJ_REQUEST_PAGES
+};
struct rbd_obj_request {
const char *object_name;
@@ -1083,6 +1085,7 @@
static bool obj_request_type_valid(enum obj_request_type type)
{
switch (type) {
+ case OBJ_REQUEST_NODATA:
case OBJ_REQUEST_BIO:
case OBJ_REQUEST_PAGES:
return true;
@@ -1306,6 +1309,12 @@
return wait_for_completion_interruptible(&obj_request->completion);
}
+static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request,
+ struct ceph_osd_op *op)
+{
+ atomic_set(&obj_request->done, 1);
+}
+
static void rbd_obj_request_complete(struct rbd_obj_request *obj_request)
{
if (obj_request->callback)
@@ -1500,6 +1509,9 @@
case CEPH_OSD_OP_WRITE:
rbd_osd_write_callback(obj_request, op);
break;
+ case CEPH_OSD_OP_WATCH:
+ rbd_osd_trivial_callback(obj_request, op);
+ break;
default:
rbd_warn(NULL, "%s: unsupported op %hu\n",
obj_request->object_name, (unsigned short) opcode);
@@ -1543,6 +1555,8 @@
rbd_assert(obj_request_type_valid(obj_request->type));
switch (obj_request->type) {
+ case OBJ_REQUEST_NODATA:
+ break; /* Nothing to do */
case OBJ_REQUEST_BIO:
rbd_assert(obj_request->bio_list != NULL);
osd_req->r_bio = obj_request->bio_list;
@@ -1635,6 +1649,8 @@
rbd_assert(obj_request_type_valid(obj_request->type));
switch (obj_request->type) {
+ case OBJ_REQUEST_NODATA:
+ break; /* Nothing to do */
case OBJ_REQUEST_BIO:
if (obj_request->bio_list)
bio_chain_put(obj_request->bio_list);
@@ -1862,6 +1878,72 @@
return 0;
}
+/*
+ * Request sync osd watch/unwatch. The value of "start" determines
+ * whether a watch request is being initiated or torn down.
+ */
+static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start)
+{
+ struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
+ struct rbd_obj_request *obj_request;
+ struct ceph_osd_req_op *op;
+ int ret;
+
+ rbd_assert(start ^ !!rbd_dev->watch_event);
+ rbd_assert(start ^ !!rbd_dev->watch_request);
+
+ if (start) {
+ ret = ceph_osdc_create_event(osdc, rbd_watch_cb, 0, rbd_dev,
+ &rbd_dev->watch_event);
+ if (ret < 0)
+ return ret;
+ }
+
+ ret = -ENOMEM;
+ obj_request = rbd_obj_request_create(rbd_dev->header_name, 0, 0,
+ OBJ_REQUEST_NODATA);
+ if (!obj_request)
+ goto out_cancel;
+
+ op = rbd_osd_req_op_create(CEPH_OSD_OP_WATCH,
+ rbd_dev->watch_event->cookie,
+ rbd_dev->header.obj_version, start);
+ if (!op)
+ goto out_cancel;
+ obj_request->osd_req = rbd_osd_req_create(rbd_dev, true,
+ obj_request, op);
+ rbd_osd_req_op_destroy(op);
+ if (!obj_request->osd_req)
+ goto out_cancel;
+
+ if (start) {
+ rbd_dev->watch_request = obj_request->osd_req;
+ ceph_osdc_set_request_linger(osdc, rbd_dev->watch_request);
+ }
+ ret = rbd_obj_request_submit(osdc, obj_request);
+ if (ret)
+ goto out_cancel;
+ ret = rbd_obj_request_wait(obj_request);
+ if (ret)
+ goto out_cancel;
+
+ ret = obj_request->result;
+ if (ret)
+ goto out_cancel;
+
+ if (start)
+ goto done; /* Done if setting up the watch request */
+out_cancel:
+ /* Cancel the event if we're tearing down, or on error */
+ ceph_osdc_cancel_event(rbd_dev->watch_event);
+ rbd_dev->watch_event = NULL;
+done:
+ if (obj_request)
+ rbd_obj_request_put(obj_request);
+
+ return ret;
+}
+
static void rbd_request_fn(struct request_queue *q)
{
struct rbd_device *rbd_dev = q->queuedata;
@@ -3879,7 +3961,8 @@
if (ret)
goto err_out_bus;
- ret = rbd_req_sync_watch(rbd_dev, 1);
+ (void) rbd_req_sync_watch; /* avoid a warning */
+ ret = rbd_dev_header_watch_sync(rbd_dev, 1);
if (ret)
goto err_out_bus;
@@ -4042,7 +4125,7 @@
rbd_dev->watch_request);
}
if (rbd_dev->watch_event)
- rbd_req_sync_watch(rbd_dev, 0);
+ rbd_dev_header_watch_sync(rbd_dev, 0);
/* clean up and free blkdev */
rbd_free_disk(rbd_dev);