Fix reservation test cases for large disks

[behlendorf]

Convert explicit typeset -i declarations to typeset -l in order
to prevent 32-bit overflow from occurs with disks >2G.

[mention-bot]

@behlendorf, thanks for your PR! By analyzing the history of the files in this pull request, we identified @tuxoko, @liaoyuxiangqin and @ChaoyuZhang to be potential reviewers.

[behlendorf]

@gmelikov increasing the default volume size to 4G causes these test cases to fail due to 32-bit arithmatic limitations of ksh. This patch disables these test case until they can be updated. @jwk404 is this an issue for OpenZFS too? If so how are you handling it?

[jwk404]

At first glance, I'd say this is a problem I introduced by using typeset -i here. The shell isn't limited to 32 bit math if you use typeset -l foo or even just typeset foo by itself. We're not seeing this in OpenZFS because these tests (only these) use bash instead of ksh. When the tests first integrated, I'd switched to bash but was asked in review to keep using ksh. Somehow this set of tests must have been overlooked.

[behlendorf]

@jwk404 spot on! Thanks for the pointer to typeset -l. I've updated the patch to make the naive fix here and converted the typeset -i instances which could overflow to typeset -l. This resolved the issue.

I didn't notice you were using bash for theses scripts either. Do you intend to switch them back to ksh? If so what's your preferred fix for this?

[jwk404]

I'll convert our tests to use ksh, and at the same time, pull in your fix and we'll be back in sync again.

[tuxoko]

But why typeset -l?

$ help typeset
-l	to convert NAMEs to lower case on assignment

Why not just remove the typeset?

[gmelikov]

@tuxoko i've read that typeset makes variables local too.

@behlendorf thanks, i'll rebase #5679 just after this PR will be merged.

[jwk404]

@tuxoko @gmelikov The -l suggestion was a misreading of the manpage on my part. The typeset should be kept though, to keep the variables local.

[behlendorf]

Right, so it looks like adding -l worked for the wrong reasons. I've update the patch to drop -l and fixed a few other places which -l was used incorrectly.