image_zfs: Allow same-as-host pool names

Use `zpool create -t` to set the in-core pool name to a temporary,
random pool name, while the on-disk name will be the name specified as
the pool name in `ZFS_POOL_NAME`, by default `zroot` to match what is
currently used on release images.

Keep the check for a possible name collision on the randomly-created
pool name, to err on the side of caution.

Inspired by:	https://reviews.freebsd.org/D34426

2 files changed, 29 insertions, 24 deletions

diff --git a/src/share/poudriere/image.sh b/src/share/poudriere/image.sh
index bfa5b0da..95d2f18c 100644
--- a/src/share/poudriere/image.sh
+++ b/src/share/poudriere/image.sh
@@ -395,7 +395,7 @@ post_getopts
 : ${SWAPSIZE:=0}
 : ${PTNAME:=default}
 : ${ZFS_SEND_FLAGS:=-Rec}
-: ${ZFS_POOL_NAME:=${IMAGENAME}root}
+: ${ZFS_POOL_NAME:=zroot}
 : ${ZFS_BEROOT_NAME:=ROOT}
 : ${ZFS_BOOTFS_NAME:=default}
 
@@ -406,6 +406,8 @@ MEDIAREMAINDER=${MEDIATYPE#*+}
 SUBMEDIATYPE=${MEDIAREMAINDER%%+*}
 MEDIAREMAINDER=${MEDIAREMAINDER#*+}
 
+TMP_ZFS_POOL_NAME="${ZFS_POOL_NAME}.$(jot -r 1 1000000000)"
+
 if [ "${MEDIATYPE}" = "none" ]; then
 	err 1 "Missing -t option"
 fi
diff --git a/src/share/poudriere/image_zfs.sh b/src/share/poudriere/image_zfs.sh
index d788f088..7b2271e7 100644
--- a/src/share/poudriere/image_zfs.sh
+++ b/src/share/poudriere/image_zfs.sh
@@ -41,8 +41,8 @@ zfs_check()
 
 	[ -n "${IMAGESIZE}" ] || err 1 "Please specify the imagesize"
 	[ -n "${ZFS_POOL_NAME}" ] || err 1 "Please specify a pool name"
-	zpool list -Ho name ${ZFS_POOL_NAME} >/dev/null 2>&1 && \
-		err 1 "Target pool name already exists"
+	zpool list -Ho name ${TMP_ZFS_POOL_NAME} >/dev/null 2>&1 && \
+		err 1 "Temporary pool name already exists"
 	case "${IMAGENAME}" in
 	''|*[!A-Za-z0-9]*)
 		err 1 "Name can only contain alphanumeric characters"
@@ -62,6 +62,7 @@ zfs_prepare()
 	truncate -s ${IMAGESIZE} ${WRKDIR}/raw.img
 	md=$(/sbin/mdconfig ${WRKDIR}/raw.img)
 	zroot=${ZFS_POOL_NAME}
+	tmpzroot=${TMP_ZFS_POOL_NAME}
 
 	msg "Creating temporary ZFS pool"
 	zpool create \
@@ -70,27 +71,28 @@ zfs_prepare()
 		-O checksum=sha512 \
 		-O compression=on \
 		-O atime=off \
+		-t ${tmpzroot} \
 		-R ${WRKDIR}/world ${zroot} /dev/${md} || exit
 
 	if [ -n "${ORIGIN_IMAGE}" ]; then
 		msg "Importing previous ZFS Datasets"
-		zfs recv -F ${zroot} < "${ORIGIN_IMAGE}"
+		zfs recv -F ${tmpzroot} < "${ORIGIN_IMAGE}"
 	else
 		msg "Creating ZFS Datasets"
-		zfs create -o mountpoint=none ${zroot}/${ZFS_BEROOT_NAME}
-		zfs create -o mountpoint=/ ${zroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}
-		zfs create -o mountpoint=/tmp -o exec=on -o setuid=off ${zroot}/tmp
-		zfs create -o mountpoint=/usr -o canmount=off ${zroot}/usr
-		zfs create ${zroot}/usr/home
-		zfs create -o setuid=off ${zroot}/usr/ports
-		zfs create ${zroot}/usr/src
-		zfs create ${zroot}/usr/obj
-		zfs create -o mountpoint=/var -o canmount=off ${zroot}/var
-		zfs create -o exec=off -o setuid=off ${zroot}/var/audit
-		zfs create -o exec=off -o setuid=off ${zroot}/var/crash
-		zfs create -o exec=off -o setuid=off ${zroot}/var/log
-		zfs create -o atime=on ${zroot}/var/mail
-		zfs create -o setuid=off ${zroot}/var/tmp
+		zfs create -o mountpoint=none ${tmpzroot}/${ZFS_BEROOT_NAME}
+		zfs create -o mountpoint=/ ${tmpzroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}
+		zfs create -o mountpoint=/tmp -o exec=on -o setuid=off ${tmpzroot}/tmp
+		zfs create -o mountpoint=/usr -o canmount=off ${tmpzroot}/usr
+		zfs create ${tmpzroot}/usr/home
+		zfs create -o setuid=off ${tmpzroot}/usr/ports
+		zfs create ${tmpzroot}/usr/src
+		zfs create ${tmpzroot}/usr/obj
+		zfs create -o mountpoint=/var -o canmount=off ${tmpzroot}/var
+		zfs create -o exec=off -o setuid=off ${tmpzroot}/var/audit
+		zfs create -o exec=off -o setuid=off ${tmpzroot}/var/crash
+		zfs create -o exec=off -o setuid=off ${tmpzroot}/var/log
+		zfs create -o atime=on ${tmpzroot}/var/mail
+		zfs create -o setuid=off ${tmpzroot}/var/tmp
 		chmod 1777 ${WRKDIR}/world/tmp ${WRKDIR}/world/var/tmp
 	fi
 }
@@ -115,11 +117,12 @@ zfs_generate()
 	: ${SNAPSHOT_NAME:=$IMAGENAME}
 	FINALIMAGE=${IMAGENAME}.img
 	zroot="${ZFS_POOL_NAME}"
-	zpool set bootfs=${zroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME} ${zroot}
-	zpool set autoexpand=on ${zroot}
-	zfs set canmount=noauto ${zroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}
+	tmpzroot="${TMP_ZFS_POOL_NAME}"
+	zpool set bootfs=${tmpzroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME} ${tmpzroot}
+	zpool set autoexpand=on ${tmpzroot}
+	zfs set canmount=noauto ${tmpzroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}
 
-	SNAPSPEC="${zroot}@${SNAPSHOT_NAME}"
+	SNAPSPEC="${tmpzroot}@${SNAPSHOT_NAME}"
 
 	msg "Creating snapshot(s) for image generation"
 	zfs snapshot -r "$SNAPSPEC"
@@ -137,7 +140,7 @@ zfs_generate()
 		esac
 		case "${MEDIAREMAINDER}" in
 		*be*)
-			BESNAPSPEC="${zroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}@${SNAPSHOT_NAME}"
+			BESNAPSPEC="${tmpzroot}/${ZFS_BEROOT_NAME}/${ZFS_BOOTFS_NAME}@${SNAPSHOT_NAME}"
 			_zfs_writereplicationstream "${BESNAPSPEC}" "${IMAGENAME}.be.zfs"
 			;;
 		esac
@@ -145,7 +148,7 @@ zfs_generate()
 	esac
 
 	## When generating a disk image, we need to export the pool first.
-	zpool export ${zroot}
+	zpool export ${tmpzroot}
 	zroot=
 	/sbin/mdconfig -d -u ${md#md}
 	md=