zfs-import: Perform verbatim import using cache file

This change modifies the import service to use the default cache file
to perform a verbatim import of pools at boot.  This fixes code that
searches all devices and imported all visible pools.

Using the cache file is in keeping with the way ZFS has always worked,
how Solaris, Illumos, FreeBSD, and systemd performs imports, and is how
it is written in the man page (zpool(1M,8)):

    All pools  in  this  cache  are  automatically imported when the
    system boots.

Importantly, the cache contains important information for importing
multipath devices, and helps control which pools get imported in more
dynamic environments like SANs, which may have thousands of visible
and constantly changing pools, which the ZFS_POOL_EXCEPTIONS variable
is not equipped to handle.  Verbatim imports prevent rogue pools from
being automatically imported and mounted where they shouldn't be.

The change also stops the service from exporting pools at shutdown.
Exporting pools is only meant to be performed explicitly by the
administrator of the system.

The old behavior of searching and importing all visible pools is
preserved and can be switched on by heeding the warning and toggling
the ZPOOL_IMPORT_ALL_VISIBLE variable in /etc/default/zfs.

Signed-off-by: James Lee <[email protected]>
Signed-off-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #3777
Closes #3526

1 files changed, 27 insertions, 53 deletions

diff --git a/etc/init.d/zfs-import.in b/etc/init.d/zfs-import.in
index 5e2192963..22586389a 100755
--- a/etc/init.d/zfs-import.in
+++ b/etc/init.d/zfs-import.in
@@ -1,11 +1,10 @@
 #!@SHELL@
 #
-# zfs-import    This script will import/export zfs pools.
+# zfs-import    This script will import ZFS pools
 #
 # chkconfig:    2345 01 99
-# description:  This script will import/export zfs pools during system
-#               boot/shutdown.
-#               It is also responsible for all userspace zfs services.
+# description:  This script will perform a verbatim import of ZFS pools
+#               during system boot.
 # probe: true
 #
 ### BEGIN INIT INFO
@@ -17,7 +16,7 @@
 # X-Start-Before:    checkfs
 # X-Stop-After:      zfs-mount
 # Short-Description: Import ZFS pools
-# Description: Run the `zpool import` or `zpool export` commands.
+# Description: Run the `zpool import` command.
 ### END INIT INFO
 #
 # NOTE: Not having '$local_fs' on Required-Start but only on Required-Stop
@@ -43,6 +42,16 @@ do_depend()
 	keyword -lxc -openvz -prefix -vserver
 }
 
+# Use the zpool cache file to import pools
+do_verbatim_import()
+{
+	if [ -f "$ZPOOL_CACHE" ]
+	then
+		zfs_action "Importing ZFS pool(s)" \
+			"$ZPOOL" import -c "$ZPOOL_CACHE" -N -a
+	fi
+}
+
 # Support function to get a list of all pools, separated with ';'
 find_pools()
 {
@@ -60,8 +69,8 @@ find_pools()
 	echo "${pools%%;}" # Return without the last ';'.
 }
 
-# Import all pools
-do_import()
+# Find and import all visible pools, even exported ones
+do_import_all_visible()
 {
 	local already_imported available_pools pool npools
 	local exception dir ZPOOL_IMPORT_PATH RET=0 r=1
@@ -109,7 +118,7 @@ do_import()
 		fi
 	fi
 
-        # Filter out any exceptions...
+	# Filter out any exceptions...
 	if [ -n "$ZFS_POOL_EXCEPTIONS" ]
 	then
 		local found=""
@@ -249,41 +258,15 @@ do_import()
 	return "$RET"
 }
 
-# Export all pools
-do_export()
+do_import()
 {
-	local already_imported pool root_pool RET r
-	RET=0
-
-	root_pool=$(get_root_pool)
-
-	[ -n "$init" ] && zfs_log_begin_msg "Exporting ZFS pool(s)"
-
-	# Find list of already imported pools.
-	already_imported=$(find_pools "$ZPOOL" list -H -oname)
-
-	OLD_IFS="$IFS" ; IFS=";"
-	for pool in $already_imported; do
-		[ "$pool" = "$root_pool" ] && continue
-
-		if [ -z "$init" ]
-		then
-			# Interactive - one 'Importing ...' line per pool
-			zfs_log_begin_msg "Exporting ZFS pool $pool"
-		else
-			# Not interactive - a dot for each pool.
-			zfs_log_progress_msg "."
-		fi
-
-		"$ZPOOL" export "$pool"
-		r="$?" ; RET=$((RET + r))
-		[ -z "$init" ] && zfs_log_end_msg "$r"
-	done
-	IFS="$OLD_IFS"
-
-	[ -n "$init" ] && zfs_log_end_msg "$RET"
-
-	return "$RET"
+	if check_boolean "$ZPOOL_IMPORT_ALL_VISIBLE"
+	then
+		do_import_all_visible
+	else
+		# This is the default option
+		do_verbatim_import
+	fi
 }
 
 # Output the status and list of pools
@@ -323,14 +306,6 @@ do_start()
 	fi
 }
 
-do_stop()
-{
-	# Check to see if the module is even loaded.
-	check_module_loaded "zfs" || exit 0
-
-	do_export
-}
-
 # ----------------------------------------------------
 
 if [ ! -e /etc/gentoo-release ]
@@ -340,7 +315,7 @@ then
 			do_start
 			;;
 		stop)
-			do_stop
+			# no-op
 			;;
 		status)
 			do_status
@@ -350,7 +325,7 @@ then
 			;;
 		*)
 			[ -n "$1" ] && echo "Error: Unknown command $1."
-			echo "Usage: $0 {start|stop|status}"
+			echo "Usage: $0 {start|status}"
 			exit 3
 			;;
 	esac
@@ -360,6 +335,5 @@ else
 	# Create wrapper functions since Gentoo don't use the case part.
 	depend() { do_depend; }
 	start() { do_start; }
-	stop() { do_stop; }
 	status() { do_status; }
 fi