tree eb973ef95389a9511c137c7c26248dfd04a2495f
parent c0da7aa1a2d8fcafe271a7077599253c8ed94bb2
author Chris Mason <chris.mason@oracle.com> 1300906482 -0400
committer root <Chris Mason chris.mason@oracle.com> 1301305042 -0400

Btrfs: use RCU instead of a spinlock to protect the root node

The pointer to the extent buffer for the root of each tree
is protected by a spinlock so that we can safely read the pointer
and take a reference on the extent buffer.

But now that the extent buffers are freed via RCU, we can safely
use rcu_read_lock instead.

Signed-off-by: Chris Mason <chris.mason@oracle.com>