xfs: stop the sync worker before xfs_unmountfs

[Christoph Hellwig]

On Wed, Sep 12, 2012 at 01:33:47PM -0500, Ben Myers wrote:
> See what you think of this.  Not heavily tested yet, and not pretty... but it
> is fairly minimal. 
> 
> Pull startup and shutdown of the sync worker out of xfs_syncd_init and
> xfs_syncd_stop into their callers.  In the case of unmount, move shutdown of
> the xfs_sync_worker before teardown of the log in xfs_unmountfs.  This prevents
> occasional crashes on unmount like so:
> 
> PID: 21602  TASK: ee9df060  CPU: 0   COMMAND: "kworker/0:3"                                                                                                                               
>  #0 [c5377d28] crash_kexec at c0292c94                                                                                                                                                    

Can you remove the trailing whitespaces in these lines?  They make
reading the changelog on a normal 80 character wide terminal pretty
hard.

The changes look fine to me,


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