ufs: Fix build errors on 32 bit machines

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.

---
 fs/ufs/balloc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 0315fea1d589..a93121873fa6 100644
@@ -459,7 +459,7 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment,
 	    case UFS_OPTSPACE:
 		request = newcount;
 		if (uspi->s_minfree < 5 || uspi->cs_total.cs_nffree
-		    > uspi->s_dsize * uspi->s_minfree / (2 * 100))
+		    > div_u64(uspi->s_dsize * uspi->s_minfree, 2 * 100))
 			break;
 		usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);
 		break;

@@ -468,8 +468,8 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment,
 	
 	    case UFS_OPTTIME:
 		request = uspi->s_fpb;
-		if (uspi->cs_total.cs_nffree < uspi->s_dsize *
-		    (uspi->s_minfree - 2) / 100)
+		if (uspi->cs_total.cs_nffree <
+		    div_u64(uspi->s_dsize * (uspi->s_minfree - 2), 100))
 			break;
 		usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);
 		break;

2.7.4

Actually, that's not the only problem in that place. The breakage came in 2.4.14.7; the critical part was this:
default:
- usb1->fs_optim = SWAB32(UFS_OPTTIME);

+               usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);
        
            case 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)
                        break;
-               usb1->fs_optim = SWAB32(UFS_OPTSPACE);
+               usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);
                break;

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 <[email protected]>
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.

[snip]

Some background: there are two possible allocation policies for the bad case of tail unpacking. If a small (less than 192K, on typical ufs1) file has the last block packed along with those of other files and we can't just expand that tail in place, we need to find a place for longer tail somewhere and copy the old data over there.

First policy: try and put it into a block already containing tail(s). Kinder on space, higher odds of having to do relocation the next time that tail needs to grow. That's what OPTSPACE is.

Second policy: pick a free block and put the expanded tail there. Better chance of being able to expand in place when/if the tail needs to grow again, harsher on space. That's OPTTIME.

The choice between those is controlled by the amount of space left in partially filled blocks. If it's high, we need to go for OPTSPACE, if it's low - OPTTIME. Cutoff values depend upon the amount of space reserved for root; for 5% (default) it's "go for OPTSPACE when more than 3% of total space are taken by free space in partially filled blocks, go for OPTTIME when fragmentation is less than 2.5%, stay with the previous state when it's between 2.5% and 3%".

(Christoph's?) typo in 2.4.14.7 has broken the switch from OPTTIME to OPTSPACE; once in OPTTIME it's stuck in OPTTIME.

Yes. Nice catch.

Agreed, but wouldn't it be more important to get the code to compile for now ? After all, optimizing the calculation is an enhancement, not a bug fix.

Thanks,
Guenter