Currently, the devicemapper library sets cookies to correlate wait operations,
which must be unique (as the lvm2 library doesn't detect duplicate cookies).
The current method for cookie generation is to take the address of a cookie
variable. However, because the variable is declared on the stack, execution
patterns can lead to the cookie variable being declared at the same stack
location, which results in a high likelyhood of duplicate cookie use, which in
turn can lead to various odd lvm behaviors, which can be hard to track down
(object use before create, duplicate completions, etc). Lets guarantee that the
cookie we generate is unique by declaring it on the heap instead. This
guarantees that the address of the variable won't be reused until such time as
the UdevWait operation completes, and drops its reference to it, at which time
the gc can reclaim it.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Upstream-commit: edd1c9e3255ddd80c97313bd596812dbb3470a5b
Component: engine
eba04294b8