writeback: fix bad _bh spinlock nesting
writeback: fix bad _bh spinlock nesting

Fix a bug where a lock is _bh nested within another _bh lock,
but forgets to use the _bh variant for unlock.

Further more, it's not necessary to test _bh locks, the inner lock
can just use spin_lock(). So fix up the bug by making that change.

Signed-off-by: Jens Axboe <08e836a620179c237f631ad0545a7ebdf54201f3@fusionio.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas