Btrfs: Various small fixes.

This trivial patch contains two locking fixes and a off by one fix.

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

diff --cc fs/btrfs/ordered-data.c
Simple merge

diff --cc fs/btrfs/root-tree.c
Simple merge

diff --cc fs/btrfs/super.c
Simple merge

diff --cc fs/btrfs/transaction.c
Simple merge

diff --cc fs/btrfs/transaction.h
Simple merge