f2fs: try grabbing node page lock aggressively in sync scenario

[ Upstream commit 4b270a8c ]

In synchronous scenario, like in checkpoint(), we are going to flush
dirty node pages to device synchronously, we can easily failed
writebacking node page due to trylock_page() failure, especially in
condition of intensive lock competition, which can cause long latency
of checkpoint(). So let's use lock_page() in synchronous scenario to
avoid this issue.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>