This is the second take of block-dm-finish-REQ_FLUSH-FUA-conversion.
I've put patches on top of the previous patches for easier review.
The series can be trivially reordered so that the order is more
logical. Jens, please let me know if you want it to be reordered.
The dm conversion is _lightly_ tested. Please proceed with caution.
Let's hold off merging these bits until dm people can verify the
conversion is correct.
* bio-based dm and requested-based dm patches are split. 0002-0003
convert bio-based dm and 0004 converts requested-based dm.
* The previous requested based dm conversion was broken in the way
requests are sequenced. This patch rips out special multi-target
handling for flushes and handles flushes the same way other requests
This patchset is on top of "block, fs: replace HARDBARRIER with
FLUSH/FUA" patchset and available in the following git tree