Messages in this thread | | | Date | Thu, 26 Jun 2008 21:21:33 +1000 | From | Dave Chinner <> | Subject | Re: [PATCH 1/6] Extend completions to provide XFS object flush requirements |
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On Thu, Jun 26, 2008 at 03:46:36AM -0400, Christoph Hellwig wrote: > On Thu, Jun 26, 2008 at 02:41:12PM +1000, Dave Chinner wrote: > > XFS object flushing doesn't quite match existing completion semantics. It > > mixed exclusive access with completion. That is, we need to mark an object as > > being flushed before flushing it to disk, and then block any other attempt to > > flush it until the completion occurs. > > > > To do this we introduce: > > > > void init_completion_flush(struct completion *x) > > which initialises x->done = 1 > > > > void completion_flush_start(struct completion *x) > > which blocks if done == 0, otherwise decrements done to zero and > > allows the caller to continue. > > > > bool completion_flush_start_nowait(struct completion *x) > > returns a failure status if done == 0, otherwise decrements done > > to zero and returns a "flush started" status. This is provided > > to allow flushing to begin safely while holding object locks in > > inverted order. > > > > This replaces the use of semaphores for providing this exclusion > > and completion mechanism. > > Given that the only API call shared with normal completions is > complete() I'd rather make this a primitive of it's own, even if > internally implemented as completions.
Ok, so that involves exactly what? A new header file, a new API name (ideas anyone?) and kerneldoc comments?
Cheers,
Dave. -- Dave Chinner david@fromorbit.com
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