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rbd: only set up watch for mapped images

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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: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2013-05-06 17:40:33 -05:00
parent 7ce4eef7b5
commit 1f3ef78861
1 changed files with 24 additions and 19 deletions
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43
drivers/block/rbd.c
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@ -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 (ret)
goto out_header_name;
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 (tmp)
rbd_warn(rbd_dev, "unable to tear down watch request\n");
if (mapping) {
tmp = rbd_dev_header_watch_sync(rbd_dev, false);
if (tmp)
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);