Re: [PATCH v3 2/4] io: Assert we have a sensible off_t

[Christoph Hellwig <hch@infradead.org>]

On Fri, Dec 15, 2023 at 01:36:41AM +0000, Sam James wrote:
> +	/* We're only interested in supporting an off_t which can handle >=4GiB. */

This adds a < 80 character line.  Also I find the wording a bit odd, the
point is that xfsprogs relies on (it or rather will with your entire
series), so maybe:

	/*
	 * xfsprogs relies on the LFS interfaces with a 64-bit off_t to
	 * actually support sensible file systems sizes.
	 */

And while I'm nitpicking, maybe a better place would be to move this to
libxfs as that's where we really care.  If you use the C99 static_assert
instead of the kernel BUILD_BUG_ON this can even move outside a function
and just into a header somewhere, say include/xfs,h.  Which actually
happens to have this assert in an awkware open coded way already:

/*
 * make sure that any user of the xfs headers has a 64bit off_t type
 */
extern int xfs_assert_largefile[sizeof(off_t)-8];

Enough of my stream of consciousness, sorry.  To summarize the findings:

 - we don't really need this patch all
 - but cleaning up xfs_assert_largefile to just use static_assert would
   probably be nice to have anyway