[PATCH 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>
---
 common/ext4 |   20 ++++++++++++++++++++
 common/rc   |    3 +++
 2 files changed, 23 insertions(+)


diff --git a/common/ext4 b/common/ext4
index 287705af..819f9786 100644
--- a/common/ext4
+++ b/common/ext4
@@ -154,3 +154,23 @@ _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 $type in
+    mkfs)
+        log_opt="-J device=$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 $SCRATCH_LOGDEV)"
+	;;
+    esac
+    [ "$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
 }