./configure script does not check for ZLIB_DEFLATE and ZLIB_INFLATE

[ryao]

Both the spl and zfs modules depend on ZLIB_DEFLATE and ZLIB_INFLATE, but neither build system checks for them. The ./configure tests should be modified to require that these options be set, much like it requires that PREEMPT be disabled.

[behlendorf]

Yes, we should add a check for this. I'm all for being totally pedantic at configure time, best to detect these things as early as possible. However, some care should be taken because depending on the distribution this support can be built in to the kernel, as a stand alone module, or both. For example, under RHEL6.2:

$ grep CONFIG_ZLIB /boot/config-2.6.32-220.el6.x86_64 
CONFIG_ZLIB_INFLATE=y
CONFIG_ZLIB_DEFLATE=m

[ryao]

While we are on the topic of ./configure script checks, we might also want to consider verifying that the kernel has CONFIG_MODULE =y. We might also want a check for CONFIG_BLK_DEV_LOOP, because the ZFS Regression Test Suite depends on it.

Checks have been placed in Gentoo to verify these constraints:

http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/sys-fs/zfs/zfs-9999.ebuild?revision=1.13

[behlendorf]

Verify zlib inflate/deflate are available either built in or as modules. I've opted not to check for the CONFIG_BLK_DEV_LOOP since supporting the test framework isn't critical for end users.

openzfs/spl@42b3ce6 Check for ZLIB_INFLATE and ZLIB_DEFLATE