fs: namespace: Make put_mnt_ns rt aware

On RT the lock() inside the preempt disabled region of get_cpu_var()
results in a might sleep warning.

Restructure the code and check the atomic transition to 0 open coded
to avoid vfsmount_write_lock() in the case when ns->count is > 1.

If ns->count == 1 then do the atomic decrement under full locking of
namespace_sem and vfsmount_write_lock(). In most cases the
atomic_dec_and_test() will have dropped ns->count to 0 so we need the
full locking anyway.

Based on a patch from John Stultz

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

0 files changed, 0 insertions, 0 deletions