Add RPM builds for scoutfs-kmod

This adds in the makefile targets and spec file template we need to
build RPMs. Most of the heavy lifting is taken care of by our docker
container and the rpmbuild.sh script distributed in it.

The git versioning comes from 'git describe --long', which gives us the
tag, the number of commits and the abbreviated commit name. This allows
us to use the number of commits as the RPM release version, letting yum
understand how to process 'yum update' ordering.

yum update shows us the proper processing, along with how our versioning
lines up in the RPMs:
---> Package kmod-scoutfs.x86_64 0:0-0.3.gb83d29d.el7 will be updated
---> Package kmod-scoutfs.x86_64 0:0-0.4.g2e5324e.el7 will be an update
The rpm file name is: kmod-scoutfs-0-0.4.g2e5324e.el7.x86_64.rpm

When we build release RPMS, we'll toggle _release, giving us a rpm name
and version like kmod-scoutfs-0-1.4.g2e5324e.el7.x86_64.rpm. The toggle
of 0/1 is enough to tell yum that all of the non-release RPMs with the
same version are older than the released RPMs. This allows for the
release to yum update cleanly over development versions.

The git hash helps map RPM names to the git version and the contents of
the .note-git_describe, for this RPM it was: heads/nic/rpms-0-g2e5324.
The RPM doesn't contain the branch name, but we can add that and other
info later if needed.

We are not naming the module for a kernel version, that does not seem to
be standard practice upstream. Instead, we'll make use of our
Artifactory repos and upload the RPMs to the correct places (7.3 vs 7.4
directories, etc).

kmod/.gitignore

@@ -10,3 +10,5 @@ cscope.*
 *.spec
 *.sw[po]
 rpmbuild/
+
+scoutfs-*.git*/

kmod/Makefile

@@ -24,11 +24,59 @@ SCOUTFS_ARGS := SCOUTFS_GIT_DESCRIBE=$(SCOUTFS_GIT_DESCRIBE) \
 		CONFIG_SCOUTFS_FS=m -C $(SK_KSRC) M=$(CURDIR)/src \
 		EXTRA_CFLAGS="-Werror"
 
+# move damage locally, this will also help make it easier to cleanup after the build
+RPM_DIR = $(shell pwd)/rpmbuild
+
+# - We use the git describe from tags to set up the RPM versioning
+RPM_VERSION := $(shell git describe --long --tags | awk -F '-' '{gsub(/^v/,""); print $$1}')
+RPM_RELEASE := $(shell git describe --long --tags | awk -F '-' '{print $$2"."$$3}')
+FULL_VERSION := $(RPM_VERSION).$(RPM_RELEASE)
+TARFILE = $(RPM_DIR)/SOURCES/scoutfs-kmod-$(FULL_VERSION).tar
+
+.PHONY: .FORCE
+
 all: module
 
 module:
 	make $(SCOUTFS_ARGS)
 	$(SP) make C=2 CF="-D__CHECK_ENDIAN__" $(SCOUTFS_ARGS)
 
+
+modules_install:
+	make $(SCOUTFS_ARGS) modules_install
+
+
+# remake this each time..
+$(RPM_DIR): .FORCE
+	@echo "## Clean up on isle $(RPM_DIR)..."
+	rm -frv $(RPM_DIR)/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
+	mkdir -p $(RPM_DIR)/{BUILD,RPMS,SOURCES,SPECS,SRPMS}
+
+
+%.spec: %.spec.in .FORCE
+	sed -e 's/@@VERSION@@/$(RPM_VERSION)/g' \
+		-e s'/@@TAR_VERSION@@/$(FULL_VERSION)/g' \
+		-e s'/@@RELEASE@@/$(RPM_RELEASE)/g' < $< > $@+
+	mv $@+ $@
+
+
+# NOTE: Both tar & rpm are capable of being built natively on Linux, provided
+# you have a local install of rpmbuild.sh for the rpm target.
+# Normal exection is to use docker, as that pulls our canned image and tooling for the user.
+# ./indocker.sh make tar
+# ./indocker.sh make rpm
+#
+tar: $(RPM_DIR) scoutfs-kmod.spec
+	git archive --format=tar --prefix scoutfs-$(FULL_VERSION)/ HEAD^{tree} > $(TARFILE)
+	@ tar rf $(TARFILE) --transform="s@\(.*\)@scoutfs-$(FULL_VERSION)/\1@" scoutfs-kmod.spec
+	gzip -f -9 $(TARFILE)
+
+
+$(TARFILE).gz: tar
+
+rpm: $(TARFILE).gz scoutfs-kmod.spec
+	rpmbuild.sh $(TARFILE).gz
+
+
 clean:
 	make $(SCOUTFS_ARGS) clean

kmod/scoutfs-kmod.spec.in

@@ -0,0 +1,72 @@
+%define kmod_name scoutfs
+#%%trace
+
+%define _tar_version @@TAR_VERSION@@
+# official builds set this to 1, we use 0 for internal/dev-test
+%{!?_release: %global _release 0}
+
+Name:           %{kmod_name}
+Summary:        %{kmod_name} kernel module
+Version:        @@VERSION@@
+Release:        %{_release}.@@RELEASE@@%{?dist}
+License:        GPLv2
+Group:          System/Kernel
+URL:            http://versity.com
+
+BuildRequires:  %kernel_module_package_buildreqs
+ExclusiveArch:  x86_64
+
+# Sources.
+Source0:        scoutfs-kmod-%{_tar_version}.tar.gz
+
+# Build only for standard kernel variant(s); for debug packages, append "debug"
+# after "default" (separated by space)
+%kernel_module_package default
+
+
+# Disable the building of the debug package(s).
+%define debug_package %{nil}
+
+%description
+%{kmod_name} - kernel module
+
+
+%prep
+
+
+%setup -q -n %{kmod_name}-%{_tar_version}
+set -- *
+mkdir source
+mv "$@" source/
+mkdir obj
+
+
+%build
+echo "Building for kernel: %{kernel_version} flavors: '%{flavors_to_build}'"
+echo "Build var: kmodtool = %{kmodtool}"
+echo "Build var: kverrel = %{kverrel}"
+for flavor in %flavors_to_build; do
+    rm -rf obj/$flavor
+    cp -r source obj/$flavor
+    make SK_KSRC=%{kernel_source $flavor} -C obj/$flavor module
+done
+
+
+%install
+export INSTALL_MOD_PATH=$RPM_BUILD_ROOT
+export INSTALL_MOD_DIR=extra/%{name}
+for flavor in %flavors_to_build ; do
+    # TODO add Makefile rule
+    #make SK_KSRC=%{kernel_source $flavor} -C obj/$flavor modules_install
+    make -C %{kernel_source $flavor} modules_install \
+        M=$PWD/obj/$flavor/src
+done
+
+
+%clean
+rm -rf %{buildroot}
+
+
+%changelog
+* Fri Nov 17 2017 Nic Henke <nic.henke@versity.com> - 1.0
+- Initial version.