sys/linux/test: mark f2fs tests as manual

Introduce "manual" requirement for tests (only run if explicitly selected)
and mark f2fs tests as manual. There are too many of them.

Follow up to #2032

pkg/runtest/run.go

@@ -198,6 +198,7 @@ nextSandbox:
 			}
 		}
 		properties := map[string]bool{
+			"manual":                  ctx.Tests != "", // "manual" tests run only if selected by the filter explicitly.
 			"arch=" + ctx.Target.Arch: true,
 			"sandbox=" + sandbox:      true,
 			"littleendian":            ctx.Target.LittleEndian,

tools/create_f2fs_image.sh

@@ -2,6 +2,11 @@
 # Copyright 2020 syzkaller project authors. All rights reserved.
 # Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
 
+# This script generates sys/linux/test/syz_image_mount_f2fs_* files.
+# Requires f2fs-tools package to be installed.
+
+set -eu
+
 declare -a Op1=("-a 0 " "-a 1 ")
 declare -a Op2=("-s 1 " "-s 2 ")
 declare -a Op3=("-m " "")
@@ -18,7 +23,11 @@ for op1 in "${Op1[@]}"; do
         echo mkfs.f2fs ${op1}${op2}${op3}${op4} disk.raw
         fallocate -l 64M disk.raw
         mkfs.f2fs "${op1}${op2}${op3}${op4}" disk.raw 
-        go run "$dir/syz-imagegen/imagegen.go" -image=./disk.raw -fs=f2fs > "$dir/../sys/linux/test/syz_image_mount_f2fs_$dex"
+        out="$dir/../sys/linux/test/syz_image_mount_f2fs_$dex"
+        echo "# Code generated by tools/create_f2fs_image.sh. DO NOT EDIT." > $out
+        echo "# requires: manual" >> $out
+        echo >> $out
+        go run "$dir/syz-imagegen/imagegen.go" -image=./disk.raw -fs=f2fs >> $out
         rm disk.raw
         dex=dex+1
       done