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Commit 1f3ef788 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: only set up watch for mapped images 

Any changes to parent images are immaterial to any mapped clone.
So there is no need to have a watch event registered on header
objects except for the header object of an image that is mapped.
In fact, a watch request is a write operation, and we may only
have read access to a parent image.

We can't set up the watch request until we know the name of the
header object though.  So pass a flag to rbd_dev_image_probe() to
indicate whether this probe is for a mapping or for a parent image.

Change the second parameter to rbd_dev_header_watch_sync() be
Boolean while we're at it.

This resolves:
    http://tracker.ceph.com/issues/4941



Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 7ce4eef7

drivers/block/rbd.c

+24 −19
Original line number Diff line number Diff line
@@ -358,7 +358,7 @@ static ssize_t rbd_add(struct bus_type *bus, const char *buf, 
		       size_t count);

static ssize_t rbd_remove(struct bus_type *bus, const char *buf,

			  size_t count);

static int rbd_dev_image_probe(struct rbd_device *rbd_dev);

static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping);



static struct bus_attribute rbd_bus_attrs[] = {

	__ATTR(add, S_IWUSR, NULL, rbd_add),
@@ -2664,7 +2664,7 @@ static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data) 
 * 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)

static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, bool start)

{

	struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;

	struct rbd_obj_request *obj_request;
@@ -2698,7 +2698,7 @@ static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start) 
					rbd_dev->watch_request->osd_req);



	osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_WATCH,

				rbd_dev->watch_event->cookie, 0, start);

				rbd_dev->watch_event->cookie, 0, start ? 1 : 0);

	rbd_osd_req_format_write(obj_request);



	ret = rbd_obj_request_submit(osdc, obj_request);
@@ -4549,7 +4549,7 @@ static int rbd_dev_probe_parent(struct rbd_device *rbd_dev) 
	if (!parent)

		goto out_err;



	ret = rbd_dev_image_probe(parent);

	ret = rbd_dev_image_probe(parent, false);

	if (ret < 0)

		goto out_err;

	rbd_dev->parent = parent;
@@ -4654,12 +4654,7 @@ static int rbd_dev_header_name(struct rbd_device *rbd_dev) 


static void rbd_dev_image_release(struct rbd_device *rbd_dev)

{

	int ret;



	rbd_dev_unprobe(rbd_dev);

	ret = rbd_dev_header_watch_sync(rbd_dev, 0);

	if (ret)

		rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);

	kfree(rbd_dev->header_name);

	rbd_dev->header_name = NULL;

	rbd_dev->image_format = 0;
@@ -4671,9 +4666,11 @@ static void rbd_dev_image_release(struct rbd_device *rbd_dev) 


/*

 * Probe for the existence of the header object for the given rbd

 * device.

 * device.  If this image is the one being mapped (i.e., not a

 * parent), initiate a watch on its header object before using that

 * object to get detailed information about the rbd image.

 */

static int rbd_dev_image_probe(struct rbd_device *rbd_dev)

static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)

{

	int ret;

	int tmp;
@@ -4693,9 +4690,11 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev) 
	if (ret)

		goto err_out_format;



	ret = rbd_dev_header_watch_sync(rbd_dev, 1);

	if (mapping) {

		ret = rbd_dev_header_watch_sync(rbd_dev, true);

		if (ret)

			goto out_header_name;

	}



	if (rbd_dev->image_format == 1)

		ret = rbd_dev_v1_header_info(rbd_dev);
@@ -4719,9 +4718,12 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev) 
err_out_probe:

	rbd_dev_unprobe(rbd_dev);

err_out_watch:

	tmp = rbd_dev_header_watch_sync(rbd_dev, 0);

	if (mapping) {

		tmp = rbd_dev_header_watch_sync(rbd_dev, false);

		if (tmp)

		rbd_warn(rbd_dev, "unable to tear down watch request\n");

			rbd_warn(rbd_dev, "unable to tear down "

					"watch request (%d)\n", tmp);

	}

out_header_name:

	kfree(rbd_dev->header_name);

	rbd_dev->header_name = NULL;
@@ -4788,7 +4790,7 @@ static ssize_t rbd_add(struct bus_type *bus, 
	rbdc = NULL;		/* rbd_dev now owns this */

	spec = NULL;		/* rbd_dev now owns this */



	rc = rbd_dev_image_probe(rbd_dev);

	rc = rbd_dev_image_probe(rbd_dev, true);

	if (rc < 0)

		goto err_out_rbd_dev;
@@ -4910,10 +4912,13 @@ static ssize_t rbd_remove(struct bus_type *bus, 
	spin_unlock_irq(&rbd_dev->lock);

	if (ret < 0)

		goto done;

	ret = count;

	rbd_bus_del_dev(rbd_dev);

	ret = rbd_dev_header_watch_sync(rbd_dev, false);

	if (ret)

		rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);

	rbd_dev_image_release(rbd_dev);

	module_put(THIS_MODULE);

	ret = count;

done:

	mutex_unlock(&ctl_mutex);