[PATCH v1.3 3/3] common/ext4: provide custom ext4 scratch fs options

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Create a _scratch_options backend for ext* so that we can inject
pathnames to external log devices into the scratch fs mount options.
This enables common/dm* to install block device filters, e.g. dm-error
for stress testing.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
v1.1: bad at counting
v1.2: refactor _scratch_mkfs_ext4 to use _scratch_options too
v1.3: quiet down realpath usage when SCRATCH_LOGDEV is unset
---
 common/ext4 |   35 ++++++++++++++++++++++++++++++++---
 common/rc   |    3 +++
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/common/ext4 b/common/ext4
index 287705af..f2df888c 100644
--- a/common/ext4
+++ b/common/ext4
@@ -63,16 +63,24 @@ _setup_large_ext4_fs()
 	return 0
 }
 
+_scratch_mkfs_ext4_opts()
+{
+	mkfs_opts=$*
+
+	_scratch_options mkfs
+
+	echo "$MKFS_EXT4_PROG $SCRATCH_OPTIONS $mkfs_opts"
+}
+
 _scratch_mkfs_ext4()
 {
-	local mkfs_cmd="$MKFS_EXT4_PROG -F"
+	local mkfs_cmd="`_scratch_mkfs_ext4_opts`"
 	local mkfs_filter="grep -v -e ^Warning: -e \"^mke2fs \" | grep -v \"^$\""
 	local tmp=`mktemp -u`
 	local mkfs_status
 
 	[ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
-	    $mkfs_cmd -O journal_dev $MKFS_OPTIONS $SCRATCH_LOGDEV && \
-	    mkfs_cmd="$mkfs_cmd -J device=$SCRATCH_LOGDEV"
+	    $MKFS_EXT4_PROG -F -O journal_dev $MKFS_OPTIONS $SCRATCH_LOGDEV
 
 	_scratch_do_mkfs "$mkfs_cmd" "$mkfs_filter" $* 2>$tmp.mkfserr 1>$tmp.mkfsstd
 	mkfs_status=$?
@@ -154,3 +162,24 @@ _require_scratch_richacl_ext4()
 		|| _notrun "kernel doesn't support richacl feature on $FSTYP"
 	_scratch_unmount
 }
+
+_scratch_ext4_options()
+{
+	local type=$1
+	local log_opt=""
+
+	case $type in
+	mkfs)
+		SCRATCH_OPTIONS="$SCRATCH_OPTIONS -F"
+		log_opt="-J device=$SCRATCH_LOGDEV"
+		;;
+	mount)
+		# As of kernel 5.19, the kernel mount option path parser only
+		# accepts direct paths to block devices--the final path
+		# component cannot be a symlink.
+		log_opt="-o journal_path=$(realpath -q "$SCRATCH_LOGDEV")"
+		;;
+	esac
+	[ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
+		SCRATCH_OPTIONS="$SCRATCH_OPTIONS ${log_opt}"
+}
diff --git a/common/rc b/common/rc
index dc1d65c3..b82bb36b 100644
--- a/common/rc
+++ b/common/rc
@@ -178,6 +178,9 @@ _scratch_options()
     "xfs")
 	_scratch_xfs_options "$@"
 	;;
+    ext2|ext3|ext4|ext4dev)
+	_scratch_ext4_options "$@"
+	;;
     esac
 }