Re: [Ext2-devel] [PATCH] fix ext3 mounts at 16T

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Andreas Dilger wrote:
On Aug 18, 2006  12:39 -0500, Eric Sandeen wrote:
@@ -168,7 +168,7 @@ goal_in_my_reservation(struct ext3_reser
 	ext3_fsblk_t group_first_block, group_last_block;
group_first_block = ext3_group_first_block_no(sb, group);
-	group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
+	group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
if ((rsv->_rsv_start > group_last_block) ||
 	    (rsv->_rsv_end < group_first_block))
@@ -897,7 +897,7 @@ static int alloc_new_reservation(struct spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock; group_first_block = ext3_group_first_block_no(sb, group);
-	group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
+	group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
if (grp_goal < 0)
 		start_block = group_first_block;

I don't see how these can make a difference?  Surely, if the intermediate
sum overflows it will then underflow when "- 1" is done?  Not that I mind,
per-se, just curious why you think this fixes anything.

Well, you're right, if it overflows then it will underflow again. And I've not observed any actual failures, and I don't expect to. But personally I guess I'd rather avoid the whole overflow in the first place... maybe I'm being silly. :)

If you think it's unnecessary code churn then we can not make this change...

-Eric
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