Re: [PATCH] ufs: Fix build errors on 32 bit machines

From: Al Viro
Date: Sat Jun 17 2017 - 14:24:20 EST

On Sat, Jun 17, 2017 at 10:35:13AM -0700, Guenter Roeck wrote:
> Various 32 builds fail with error messages such as
> ERROR: "__udivdi3" [fs/ufs/ufs.ko] undefined!
> due to a variable type change from 32 bit to 64 bit.

Actually, that's not the only problem in that place. The breakage
came in; the critical part was this:
- usb1->fs_optim = SWAB32(UFS_OPTTIME);
+ usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);

request = uspi->s_fpb;
- if (SWAB32(usb1->fs_cstotal.cs_nffree) < uspi->s_dsize *
+ if (fs32_to_cpu(sb, usb1->fs_cstotal.cs_nffree) < uspi->s_dsize *
(uspi->s_minfree - 2) / 100)
- usb1->fs_optim = SWAB32(UFS_OPTSPACE);
+ usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);

See the problem? Instead of hysteresis loop flipping between optspace and opttime
allocation policies, it *never* switches out of opttime.

That came in

commit 6293d56ca18db9ed322b2a5550ac7b27bd538cff
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Mon Feb 4 20:33:51 2002 -0800

v2.4.14.6 -> v2.4.14.7

- Jeff Garzik: network driver updates
- Christoph Hellwig: UFS filesystem byteorder cleanups
- me: modified Andrea VM page allocator tuning

so probably a typo in Christoph's patches, missed by everyone at the time.

And I would prefer to have the nffree levels at which we switch back and
forth precalculated at mount time. I'll send a fix (along with those
for the last remaining xfstests failures) later today.