f2fs: call mark_inode_dirty to flush dirty pages

If a dentry page is updated, we should call mark_inode_dirty to add the inode
into the dirty list, so that its dentry pages are flushed to the disk.
Otherwise, the inode can be evicted without flush.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --cc fs/f2fs/data.c
Simple merge

diff --cc fs/f2fs/dir.c
Simple merge

diff --cc fs/f2fs/namei.c
Simple merge