Re: [PATCH v4 2/5] btrfs: use BIOs instead of buffer_heads from superblock writeout

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Thu, Feb 06, 2020 at 08:20:16AM +0000, Johannes Thumshirn wrote:
> >>   		op_flags = REQ_SYNC | REQ_META | REQ_PRIO;
> >>   		if (i == 0 && !btrfs_test_opt(device->fs_info, NOBARRIER))
> >>   			op_flags |= REQ_FUA;
> > 
> >> +		bio->bi_opf = REQ_OP_WRITE | op_flags;
> > 
> > You could kill the op_flags variable and just assign everything directly
> > to bio->bi_opf.
> > 
> 
> Then I'd still have to deal with the NOBARRIER mount option here so 
> op_flags is nice to have for readability.

I tend to disagree.  The simple version is:

		bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_META | REQ_PRIO;
		if (i == 0 && !btrfs_test_opt(device->fs_info, NOBARRIER))
			bio->bi_opf |= REQ_FUA;