On 07/26/2012 12:11 PM, Alex Elder wrote:
When an rbd image is mapped, a watch request is issued so that the
client will get notified in the event the image header object
changes. This is done using rbd_init_watch_dev(), which calls
rbd_req_sync_watch().
rbd_init_watch_dev() is organized as a loop, arranging to re-issue
the request after refreshing the header if -ERANGE ever gets
returned. But the only way rbd_req_sync_watch() will return -ERANGE
is if the CEPH_OSD_OP_WATCH operation returns that, which it will
not.
As a result, the whole looping structure and in fact the whole
function becomes excessive. So get rid of rbd_init_watch_dev(),
and call rbd_req_sync_watch() directly in the one place it's used.
Instead of getting rid of this loop, we should make it
send a compound operation consisting of (CEPH_OSD_OP_ASSERT_VER,
CEPH_OSD_OP_WATCH). Then we will get -ERANGE if our version
of the header is out of data, so we don't lose header updates
before the watch is established.
Josh
Signed-off-by: Alex Elder <[email protected]>
---
drivers/block/rbd.c | 18 +-----------------
1 file changed, 1 insertion(+), 17 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 94d0745..71e3f3b 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2191,22 +2191,6 @@ static void rbd_bus_del_dev(struct rbd_device
*rbd_dev)
device_unregister(&rbd_dev->dev);
}
-static int rbd_init_watch_dev(struct rbd_device *rbd_dev)
-{
- int ret, rc;
-
- do {
- ret = rbd_req_sync_watch(rbd_dev);
- if (ret == -ERANGE) {
- rc = rbd_refresh_header(rbd_dev, NULL);
- if (rc < 0)
- return rc;
- }
- } while (ret == -ERANGE);
-
- return ret;
-}
-
static atomic64_t rbd_id_max = ATOMIC64_INIT(0);
/*
@@ -2510,7 +2494,7 @@ static ssize_t rbd_add(struct bus_type *bus,
if (rc)
goto err_out_bus;
- rc = rbd_init_watch_dev(rbd_dev);
+ rc = rbd_req_sync_watch(rbd_dev);
if (rc)
goto err_out_bus;
--
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