zfsd(8), the ZFS fault management daemon

Add zfsd, which deals with hard drive faults in ZFS pools. It manages
hotspares and replements in drive slots that publish physical paths.

cddl/usr.sbin/zfsd
	Add zfsd(8) and its unit tests

cddl/usr.sbin/Makefile
	Add zfsd to the build

lib/libdevdctl
	A C++ library that helps devd clients process events

lib/Makefile
share/mk/bsd.libnames.mk
share/mk/src.libnames.mk
	Add libdevdctl to the build. It's a private library, unusable by
	out-of-tree software.

etc/defaults/rc.conf
	By default, set zfsd_enable to NO

etc/mtree/BSD.include.dist
	Add a directory for libdevdctl's include files

etc/mtree/BSD.tests.dist
	Add a directory for zfsd's unit tests

etc/mtree/BSD.var.dist
	Add /var/db/zfsd/cases, where zfsd stores case files while it's shut
	down.

etc/rc.d/Makefile
etc/rc.d/zfsd
	Add zfsd's rc script

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c
	Fix the resource.fs.zfs.statechange message. It had a number of
	problems:

	It was only being emitted on a transition to the HEALTHY state.
	That made it impossible for zfsd to take actions based on drives
	getting sicker.

	It compared the new state to vdev_prevstate, which is the state that
	the vdev had the last time it was opened.  That doesn't make sense,
	because a vdev can change state multiple times without being
	reopened.

	vdev_set_state contains logic that will change the device's new
	state based on various conditions.  However, the statechange event
	was being posted _before_ that logic took effect.  Now it's being
	posted after.

Submitted by:	gibbs, asomers, mav, allanjude
Reviewed by:	mav, delphij
Relnotes:	yes
Sponsored by:	Spectra Logic Corp, iX Systems
Differential Revision:	https://reviews.freebsd.org/D6564

6 files changed, 33 insertions, 3 deletions

diff --git a/etc/defaults/rc.conf b/etc/defaults/rc.conf
index 74125d1..80061d1 100644
--- a/etc/defaults/rc.conf
+++ b/etc/defaults/rc.conf
@@ -60,6 +60,10 @@ rc_conf_files="/etc/rc.conf /etc/rc.conf.local"
 # ZFS support
 zfs_enable="NO"		# Set to YES to automatically mount ZFS file systems
 
+# ZFSD support
+zfsd_enable="NO"	# Set to YES to automatically start the ZFS fault
+			# management daemon.
+
 gptboot_enable="YES"	# GPT boot success/failure reporting.
 
 # Experimental - test before enabling
diff --git a/etc/mtree/BSD.include.dist b/etc/mtree/BSD.include.dist
index a9baa7e..42980d0 100644
--- a/etc/mtree/BSD.include.dist
+++ b/etc/mtree/BSD.include.dist
@@ -155,6 +155,8 @@
         wi
         ..
     ..
+    devdctl
+    ..
     edit
         readline
         ..
diff --git a/etc/mtree/BSD.tests.dist b/etc/mtree/BSD.tests.dist
index f18091d..21959c4 100644
--- a/etc/mtree/BSD.tests.dist
+++ b/etc/mtree/BSD.tests.dist
@@ -48,8 +48,6 @@
     cddl
         lib
         ..
-        sbin
-        ..
         usr.bin
         ..
         usr.sbin
@@ -215,6 +213,8 @@
                     ..
                 ..
             ..
+            zfsd
+            ..
         ..
     ..
     etc
@@ -308,6 +308,8 @@
         ..
         libcrypt
         ..
+        libdevdctl
+        ..
         libmp
         ..
         libnv
diff --git a/etc/mtree/BSD.var.dist b/etc/mtree/BSD.var.dist
index 46b8dcd..e6dfa50 100644
--- a/etc/mtree/BSD.var.dist
+++ b/etc/mtree/BSD.var.dist
@@ -54,6 +54,10 @@
         ..
         portsnap
         ..
+        zfsd
+            cases
+            ..
+        ..
     ..
     empty           mode=0555 flags=schg
     ..
diff --git a/etc/rc.d/Makefile b/etc/rc.d/Makefile
index 89d2baf..e5f15e7 100644
--- a/etc/rc.d/Makefile
+++ b/etc/rc.d/Makefile
@@ -123,7 +123,7 @@ FILES=	DAEMON \
 	ypserv \
 	ypset \
 	ypupdated \
-	ypxfrd \
+	ypxfrd
 
 .if ${MK_ACCT} != "no"
 FILESGROUPS+=	ACCT
@@ -308,6 +308,7 @@ FILES+=		wpa_supplicant
 .if ${MK_ZFS} != "no"
 FILESGROUPS+=	ZFS
 ZFS+=		zfs
+ZFS+=		zfsd
 ZFS+=		zvol
 ZFSPACKAGE=	zfs
 .endif
diff --git a/etc/rc.d/zfsd b/etc/rc.d/zfsd
new file mode 100644
index 0000000..edf259b
--- /dev/null
+++ b/etc/rc.d/zfsd
@@ -0,0 +1,17 @@
+#!/bin/sh
+#
+# $FreeBSD$
+#
+
+# PROVIDE: zfsd
+# REQUIRE: devd zfs
+# KEYWORD: nojail shutdown
+
+. /etc/rc.subr
+
+name="zfsd"
+rcvar="zfsd_enable"
+command="/usr/sbin/${name}"
+
+load_rc_config $name
+run_rc_command "$1"