ext4: Use new framework for data=ordered mode in JBD2

ext4: Use new framework for data=ordered mode in JBD2

This patch makes ext4 use inode-based implementation of data=ordered mode
in JBD2. It allows us to unify some data=ordered and data=writeback paths
(especially writepage since we don't have to start a transaction anymore)
and remove some buffer walking.

Updated fix from Aneesh Kumar K.V <[email protected]>
to fix file system hang due to corrupt jinode values.

Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Signed-off-by: Mingming Cao <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>