Re: [RFC PATCH v4 5/8] xfs: refactor the truncating order

[Christoph Hellwig]

> +	write_back = newsize > ip->i_disk_size && oldsize != ip->i_disk_size;

Maybe need_writeback would be a better name for the variable?  Also no
need to initialize it to false at declaration time if it is
unconditionally set here.

> +		/*
> +		 * Updating i_size after writing back to make sure the zeroed
> +		 * blocks could been written out, and drop all the page cache
> +		 * range that beyond blocksize aligned new EOF block.
> +		 *
> +		 * We've already locked out new page faults, so now we can
> +		 * safely remove pages from the page cache knowing they won't
> +		 * get refaulted until we drop the XFS_MMAP_EXCL lock after the
> +		 * extent manipulations are complete.
> +		 */
> +		i_size_write(inode, newsize);
> +		truncate_pagecache(inode, roundup_64(newsize, blocksize));

Any reason this open codes truncate_setsize()?