Create /proc/sys/kernel/spl/gitrev with git hash

The existing mechanisms for determining what code is running in the
kernel do not always correctly report the git hash.  The versions
reported there do not reflect changes made since `configure` was run
(i.e. incremental builds do not update the version) and they are
misleading if git tags are not set up properly.  This applies to
`modinfo zfs`, `dmesg`, and `/sys/module/zfs/version`.

There are complicated requirements on how the existing version is
generated.  Therefore we are leaving that alone, and adding a new
mechanism to record and retrieve the git hash:
`cat /proc/sys/kernel/spl/gitrev`

The gitrev is re-generated at compile time, when running `make`
(including for incremental builds).  The value is the output of `git
describe` (or "unknown" if not in a git repo or there are uncommitted
changes).

We're also removing /proc/sys/kernel/spl/version, which was never very
useful.

Reviewed by: Pavel Zakharov <[email protected]>
Reviewed by: Brian Behlendorf <[email protected]>
Reviewed by: Tim Chase <[email protected]>
Signed-off-by: Matthew Ahrens <[email protected]>
Closes #7931 
Closes #7965 

9 files changed, 74 insertions, 9 deletions

diff --git a/Makefile.am b/Makefile.am
index 50b80b945..782b88c2f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -25,6 +25,12 @@ EXTRA_DIST += META AUTHORS COPYRIGHT LICENSE NEWS NOTICE README.md
 
 @CODE_COVERAGE_RULES@
 
+.PHONY: gitrev
+gitrev:
+	-${top_srcdir}/scripts/make_gitrev.sh
+
+BUILT_SOURCES = gitrev
+
 distclean-local::
 	-$(RM) -R autom4te*.cache
 	-find . \( -name SCCS -o -name BitKeeper -o -name .svn -o -name CVS \
@@ -40,7 +46,8 @@ distclean-local::
 all-local:
 	-${top_srcdir}/scripts/zfs-tests.sh -c
 
-dist-hook:
+dist-hook: gitrev
+	cp ${top_srcdir}/include/zfs_gitrev.h $(distdir)/include; \
 	sed -i 's/Release:[[:print:]]*/Release:      $(RELEASE)/' \
 		$(distdir)/META
 
diff --git a/copy-builtin b/copy-builtin
index 8be8b4381..eaffbd2d2 100755
--- a/copy-builtin
+++ b/copy-builtin
@@ -30,6 +30,7 @@ then
 fi
 
 make clean || true
+scripts/make_gitrev.sh
 
 rm -rf "$KERNEL_DIR/include/zfs" "$KERNEL_DIR/fs/zfs"
 cp --recursive include "$KERNEL_DIR/include/zfs"
diff --git a/include/.gitignore b/include/.gitignore
new file mode 100644
index 000000000..e6eb2116f
--- /dev/null
+++ b/include/.gitignore
@@ -0,0 +1 @@
+/zfs_gitrev.h
diff --git a/include/spl/sys/sysmacros.h b/include/spl/sys/sysmacros.h
index e4bd80aa1..e11eaece5 100644
--- a/include/spl/sys/sysmacros.h
+++ b/include/spl/sys/sysmacros.h
@@ -141,7 +141,7 @@
 #define	DTRACE_PROBE4(a, b, c, d, e, f, g, h, i)	((void)0)
 
 /* Missing globals */
-extern char spl_version[32];
+extern char spl_gitrev[64];
 extern unsigned long spl_hostid;
 
 /* Missing misc functions */
diff --git a/module/spl/spl-generic.c b/module/spl/spl-generic.c
index 7c1ad390b..a22e93e36 100644
--- a/module/spl/spl-generic.c
+++ b/module/spl/spl-generic.c
@@ -45,9 +45,9 @@
 #include <sys/random.h>
 #include <sys/strings.h>
 #include <linux/kmod.h>
+#include "zfs_gitrev.h"
 
-char spl_version[32] = "SPL v" ZFS_META_VERSION "-" ZFS_META_RELEASE;
-EXPORT_SYMBOL(spl_version);
+char spl_gitrev[64] = ZFS_META_GITREV;
 
 /* BEGIN CSTYLED */
 unsigned long spl_hostid = 0;
diff --git a/module/spl/spl-proc.c b/module/spl/spl-proc.c
index 9c52924a4..a75bcc214 100644
--- a/module/spl/spl-proc.c
+++ b/module/spl/spl-proc.c
@@ -659,9 +659,9 @@ static struct ctl_table spl_table[] = {
 	 * sysctl(8) prefers to go via /proc for portability.
 	 */
 	{
-		.procname	= "version",
-		.data		= spl_version,
-		.maxlen		= sizeof (spl_version),
+		.procname	= "gitrev",
+		.data		= spl_gitrev,
+		.maxlen		= sizeof (spl_gitrev),
 		.mode		= 0444,
 		.proc_handler	= &proc_dostring,
 	},
diff --git a/module/zfs/spa_history.c b/module/zfs/spa_history.c
index 969fdb000..b590a1d57 100644
--- a/module/zfs/spa_history.c
+++ b/module/zfs/spa_history.c
@@ -38,6 +38,7 @@
 #include <sys/sunddi.h>
 #include <sys/cred.h>
 #include "zfs_comutil.h"
+#include "zfs_gitrev.h"
 #ifdef _KERNEL
 #include <sys/zone.h>
 #endif
@@ -617,8 +618,8 @@ spa_history_log_version(spa_t *spa, const char *operation, dmu_tx_t *tx)
 	utsname_t *u = utsname();
 
 	spa_history_log_internal(spa, operation, tx,
-	    "pool version %llu; software version %llu/%llu; uts %s %s %s %s",
-	    (u_longlong_t)spa_version(spa), SPA_VERSION, ZPL_VERSION,
+	    "pool version %llu; software version %s; uts %s %s %s %s",
+	    (u_longlong_t)spa_version(spa), ZFS_META_GITREV,
 	    u->nodename, u->release, u->version, u->machine);
 }
 
diff --git a/scripts/Makefile.am b/scripts/Makefile.am
index 28d618562..de0d4795d 100644
--- a/scripts/Makefile.am
+++ b/scripts/Makefile.am
@@ -14,6 +14,7 @@ EXTRA_DIST = \
 	dkms.postbuild \
 	enum-extract.pl \
 	kmodtool \
+	make_gitrev.sh \
 	paxcheck.sh \
 	zfs2zol-patch.sed \
 	cstyle.pl
diff --git a/scripts/make_gitrev.sh b/scripts/make_gitrev.sh
new file mode 100755
index 000000000..04be09595
--- /dev/null
+++ b/scripts/make_gitrev.sh
@@ -0,0 +1,54 @@
+#!/bin/sh
+
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2018 by Delphix. All rights reserved.
+#
+
+#
+# Generate zfs_gitrev.h.  Note that we need to do this for every
+# invocation of `make`, including for incremental builds.  Therefore we
+# can't use a zfs_gitrev.h.in file which would be processed only when
+# `configure` is run.
+#
+
+BASE_DIR=$(dirname "$0")
+
+file=${BASE_DIR}/../include/zfs_gitrev.h
+
+#
+# Set default file contents in case we bail.
+#
+rm -f "$file"
+# shellcheck disable=SC2039
+/bin/echo -e "#define\tZFS_META_GITREV \"unknown\"" >>"$file"
+
+#
+# Check if git is installed and we are in a git repo.
+#
+git rev-parse --git-dir > /dev/null 2>&1 || exit
+
+#
+# Check if there are uncommitted changes
+#
+git diff-index --quiet HEAD || exit
+
+rev=$(git describe 2>/dev/null) || exit
+
+rm -f "$file"
+# shellcheck disable=SC2039
+/bin/echo -e "#define\tZFS_META_GITREV \"${rev}\"" >>"$file"