From cb91fa3c78a8003f092fd034dd3c5c0f230a1a85 Mon Sep 17 00:00:00 2001
From: "Brian C. Lane" <bcl@redhat.com>
Date: Thu, 25 Jul 2019 09:57:43 -0700
Subject: [PATCH] livemedia-creator: Add support for a squashfs only runtime
 image

Normally the runtime image is an ext4 filesystem image that is
compressed with squashfs. dracut now supports setting up an overlayfs
when it detects a bare filesystem tree inside the squashfs.

This commit adds support for a --squashfs-only option which places the
root tree directly in the squashfs.img
---
 src/pylorax/cmdline.py |  2 ++
 src/pylorax/creator.py | 58 +++++++++++++++++++++++++++++-------------
 2 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/src/pylorax/cmdline.py b/src/pylorax/cmdline.py
index f37d2a17..8388e8ee 100644
--- a/src/pylorax/cmdline.py
+++ b/src/pylorax/cmdline.py
@@ -303,6 +303,8 @@ def lmc_parser(dracut_default=""):
     parser.add_argument("--releasever", default="29",
                         help="substituted for @VERSION@ in bootloader config files")
     parser.add_argument("--volid", default=None, help="volume id")
+    parser.add_argument("--squashfs-only", action="store_true", default=False,
+                        help="Use a plain squashfs filesystem for the runtime.")
     parser.add_argument("--squashfs_args",
                         help="additional squashfs args")
     parser.add_argument("--timeout", default=None, type=int,
diff --git a/src/pylorax/creator.py b/src/pylorax/creator.py
index c004f34a..54ac6c1d 100644
--- a/src/pylorax/creator.py
+++ b/src/pylorax/creator.py
@@ -202,9 +202,15 @@ def make_runtime(opts, mount_dir, work_dir, size=None):
 
     rb = RuntimeBuilder(product, arch, fake_dbo)
     compression, compressargs = squashfs_args(opts)
-    log.info("Creating runtime")
-    rb.create_ext4_runtime(joinpaths(work_dir, RUNTIME), size=size,
-                      compression=compression, compressargs=compressargs)
+
+    if opts.squashfs_only:
+        log.info("Creating a squashfs only runtime")
+        rb.create_squashfs_runtime(joinpaths(work_dir, RUNTIME), size=size,
+                                   compression=compression, compressargs=compressargs)
+    else:
+        log.info("Creating a squashfs+ext4 runtime")
+        rb.create_ext4_runtime(joinpaths(work_dir, RUNTIME), size=size,
+                          compression=compression, compressargs=compressargs)
 
 
 def rebuild_initrds_for_live(opts, sys_root_dir, results_dir):
@@ -418,25 +424,41 @@ def make_squashfs(opts, disk_img, work_dir):
     out any deleted blocks to make it compress better. If this fails for any reason
     it will return False and log the error.
     """
-    # Make sure free blocks are actually zeroed so it will compress
-    rc = execWithRedirect("/usr/sbin/fsck.ext4", ["-y", "-f", "-E", "discard", disk_img])
-    if rc != 0:
-        log.error("Problem zeroing free blocks of %s", disk_img)
-        return False
-
-    liveos_dir = joinpaths(work_dir, "runtime/LiveOS")
-    os.makedirs(liveos_dir)
     os.makedirs(os.path.dirname(joinpaths(work_dir, RUNTIME)))
+    if opts.squashfs_only:
+        log.info("Creating a squashfs only runtime")
+        liveos_dir = joinpaths(work_dir, "runtime")
+        os.makedirs(liveos_dir)
+        with Mount(disk_img, opts="loop", mnt=liveos_dir):
+            compression, compressargs = squashfs_args(opts)
+            rc = mksquashfs(liveos_dir, joinpaths(work_dir, RUNTIME), compression, compressargs)
+    else:
+        log.info("Creating a squashfs+ext4 runtime")
+        # Make sure free blocks are actually zeroed so it will compress
+        rc = execWithRedirect("/usr/sbin/fsck.ext4", ["-y", "-f", "-E", "discard", disk_img])
+        if rc != 0:
+            log.error("Problem zeroing free blocks of %s", disk_img)
+            return False
 
-    rc = execWithRedirect("/bin/ln", [disk_img, joinpaths(liveos_dir, "rootfs.img")])
-    if rc != 0:
-        shutil.copy2(disk_img, joinpaths(liveos_dir, "rootfs.img"))
+        liveos_dir = joinpaths(work_dir, "runtime/LiveOS")
+        os.makedirs(liveos_dir)
 
-    compression, compressargs = squashfs_args(opts)
-    mksquashfs(joinpaths(work_dir, "runtime"),
-               joinpaths(work_dir, RUNTIME), compression, compressargs)
+        # Try to hardlink the rootfs file first, fall back top copying it
+        rc = execWithRedirect("/bin/ln", [disk_img, joinpaths(liveos_dir, "rootfs.img")])
+        if rc != 0:
+            shutil.copy2(disk_img, joinpaths(liveos_dir, "rootfs.img"))
+
+        compression, compressargs = squashfs_args(opts)
+        rc = mksquashfs(joinpaths(work_dir, "runtime"), joinpaths(work_dir, RUNTIME), compression, compressargs)
+
+    # Cleanup the runtime directory
     remove(joinpaths(work_dir, "runtime"))
-    return True
+
+    if rc:
+        log.error("Problem running mksquashfs: rc=%d", rc)
+        return False
+    else:
+        return True
 
 def calculate_disk_size(opts, ks):
     """ Calculate the disk size from the kickstart