ext4: force buffer up-to-date while marking it dirty

Writeback errors can leave buffer in not up-to-date state when there
are errors during background writes. Force buffer up-to-date while
marking it dirty.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20191224190940.157952-1-harshadshirwadkar@gmail.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>