[PATCH] xfs: unmount does not wait for shutdown during unmount

[Christoph Hellwig]

On Tue, Apr 15, 2014 at 10:59:25AM -0400, Brian Foster wrote:
> Yeah, I noticed that the completion wouldn't fire as is since it appears
> that doesn't occur if a b_iodone call is provided. FWIW, the thought
> process was more to inherit the use of b_iowait in xlog_iodone().

That doesn't mean the b_iodone callback couldn't do the wakeup on
b_iowait.

I have to say it makes me a bit uneasy that we had to find this
race the hard way for the superblock, and now for the logbufs again.

Seems like all other uncached buffers are only read and written
synchronously, so for this should be the last issue, but I fear about
new ones showing up in the future and would prefer a more general
solution.

Reluctantly:

Reviewed-by: Christoph Hellwig <hch at lst.de>