Remove spl-dkms conflict with spl-kmod

Because the spl-dkms package also provides spl-kmod for the
spl user package yum flags this as a conflict.  To avoid the
problem remove the Conflicts tag from spl-dkms and just rely
on the one in spl-kmod.

  spl-dkms-0.6.0-rc14.fc18.noarch has installed conflicts
    spl-kmod: spl-dkms-0.6.0-rc14.fc18.noarch

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Use requested kernel for dkms builds

The --with-linux and --with-linux-obj options must be specified
as part of the dkms build otherwise the package will be built
against the running kernel.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Do not call cond_resched() in spl_slab_reclaim()

Calling cond_resched() after each object is freed and then after each
slab is freed can cause slabs of objects to live for excessive periods
of time following reclaimation. This interferes with the kernel's own
memory management when called from kswapd and can cause direct reclaim
to occur in response to memory pressure that should have been resolved.

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Use 'git describe' for working builds

When building from an arbitrary commit in the git tree it's useful
for the resulting packages to be uniquely identifiable.  Therefore,
the build system has been updated to detect if your compiling in
git tree.

If you are building in a git tree, and there are commits after the
last annotated tag.  Then the <id>-<hash> component of 'git describe'
will be used to overwrite the 'Release:' field in the META file.

The only tricky part is that to ensure the 'make dist' tarball is
built using the correct release.  A dist-hook was added to the top
level make file to rewrite the META file using the correct release.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #195
Issue #111
Merge remote-tracking branch 'upstream/master'