Re: RFC: #f FreeBSD_version of #ifdef <feature> for OpenZFS pull request

Thanks, I've gone with B, rick

On Wed, Nov 22, 2023 at 1:30 PM Warner Losh <imp@bsdimp.com> wrote:
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>
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> On Wed, Nov 22, 2023, 1:24 PM Rick Macklem <rick.macklem@gmail.com> wrote:
>>
>> Hi,
>>
>> I have a patch currently under review at D42672 that fixes visibility
>> of snapshots under .zfs/snapshot for NFS clients.
>> It adds a new function called vfs_exjail_clone(), which the ZFS
>> code needs to use to fill in the mnt_exjail field.
>>
>> Since the OpenZFS code is supposed to build for 12.2 or later,
>> I can see two ways of doing this:
>> (A) #if on the FreeBSD_versions, which will look something like:
>>
>> #if (__FreeBSD_version >= 1300xxx && __FreeBSD_version < 1400000) ||
>>      (__FreeBSD_version >= 1400yyy && __FreeBSD_version < 1400500) ||
>>      (__FreeBSD_version >= 1400zzz && __FreeBSD_version < 1500000) ||
>>      __FreeBSD_version >= 1500wwww
>>          vfs_exjail_clone();
>> #endif
>>
>> The problem with this one is I do not know what www, xxx, yyy and zzz are
>> until I have MFC'd the patch and bumped __FreeBSD_version.
>> --> I cannot generate the OpenZFS pull request until after that and,
>>      since I am headed to Florida for a few weeks, it would be late December
>>      at the earliest.
>> OR
>> (B) add a line like
>> #define VFS_SUPPORTS_EXJAIL_CLONE    1
>> to mount.h in the patch and then:
>>
>> #ifdef VFS_SUPPORTS_EXJAIL_CLONE
>>          vfs_exjail_clone();
>> #endif
>>
>> The adavntage of (B) is that I can do the pull request on OpenZFS
>> right away and commit the patch to main, etc as soon as possible,
>>
>> So, which do you think is preferred? rick
>> ps: Unless D42672 gets reviewed soon, it won't really matter w.r.t. timing.
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>
> I'd do B if I were doing this. With a comment for why I'm doing this define. Then version numbers don't matter unless we botch something badly and need them as a fallback.
>
> Warner
>