Btrfs: remove root_log_ctx from ctx list before btrfs_sync_log returns

commit cbd60aa7 upstream.

We use a btrfs_log_ctx structure to pass information into the
tree log commit, and get error values out.  It gets added to a per
log-transaction list which we walk when things go bad.

Commit d1433deb added an optimization to skip waiting for the log
commit, but didn't take root_log_ctx out of the list.  This
patch makes sure we remove things before exiting.

Signed-off-by: Chris Mason <clm@fb.com>
Fixes: d1433deb
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>