Re: [PATCH v6 04/13] xfs: pass flags to xfs_reflink_allocate_cow()

[Christoph Hellwig]

On Thu, Mar 13, 2025 at 05:13:01PM +0000, John Garry wrote:
> @@ -823,6 +824,9 @@ xfs_direct_write_iomap_begin(
>  	if (xfs_is_shutdown(mp))
>  		return -EIO;
>  
> +	if (flags & IOMAP_DIRECT || IS_DAX(inode))
> +		reflink_flags |= XFS_REFLINK_CONVERT_UNWRITTEN;

Given that this is where the policy is implemented now, this comment:

	/*
	 * COW fork extents are supposed to remain unwritten until we're ready
         * to initiate a disk write.  For direct I/O we are going to write the
	 * data and need the conversion, but for buffered writes we're done.
         */        

from xfs_reflink_convert_unwritten should probably move here now.

> -	return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
> +	return xfs_reflink_convert_unwritten(ip, imap, cmap,
> +			flags & XFS_REFLINK_CONVERT_UNWRITTEN);

I'd probably thread the flags argument all the way through
xfs_reflink_convert_unwritten as that documents the intent better.

> +/*
> + * Flags for xfs_reflink_allocate_cow() and callees
> + */

And the full sentence with a .?