Date: Tue Aug 5 17:34:21 AEST 2008
The following file(s) were checked into:
include/linux/completion.h - 1.6 - changed
- extend completions to provide XFS object flush requirements
XFS object flushing doesn't quite match existing completion
mixed exclusive access with completion. That is, we need to mark an
being flushed before flushing it to disk, and then block any other
flush it until the completion occurs. We do this but adding an extra
the completion before we start using them. However, we still need to
determine if there is a completion in progress, and allow no-blocking
fo completions to decrement the count.
To do this we introduce:
int try_wait_for_completion(struct completion *x)
returns a failure status if done == 0, otherwise decrements done
to zero and returns a "started" status. This is provided
to allow counted completions to begin safely while holding
object locks in inverted order.
int completion_done(struct completion *x)
returns 1 if there is no waiter, 0 if there is a waiter
(i.e. a completion in progress).
This replaces the use of semaphores for providing this exclusion
and completion mechanism.
Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>