wic: Optimise fstab modification for ext2/3/4 and msdos partitions

The fix for [Yocto #13994] required the rootfs directory to be copied
(using hardlinks if possible) when modifying the fstab file under wic.

We can optimise this copy away for filesystems where we have the tools
to modify the contents of the partition image after it is created. For
ext2/3/4 filesystems we have the debugfs tool and for msdos/vfat
filesystems we have the mcopy tool. So for any of these filesystems we
skip the modification of the fstab file in the rootfs directory (and
skip the associated copy unless it is otherwise necessary) and update
the contents of fstab directly in the partition image.

Signed-off-by: Paul Barker <pbarker@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 5fb8ae0e9159597d7eaa9307a3a8543800bf9405)
Signed-off-by: Steve Sakoman <steve@sakoman.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/scripts/lib/wic/partition.py b/scripts/lib/wic/partition.py
index f59eceb23d..e574f40c47 100644
--- a/scripts/lib/wic/partition.py
+++ b/scripts/lib/wic/partition.py
@@ -55,6 +55,8 @@ class Partition():
         self.fsuuid = args.fsuuid
         self.type = args.type
         self.updated_fstab_path = None
+        self.has_fstab = False
+        self.update_fstab_in_rootfs = False
 
         self.lineno = lineno
         self.source_file = ""
@@ -125,6 +127,8 @@ class Partition():
         partition command parameters.
         """
         self.updated_fstab_path = updated_fstab_path
+        if self.updated_fstab_path and not (self.fstype.startswith("ext") or self.fstype == "msdos"):
+            self.update_fstab_in_rootfs = True
 
         if not self.source:
             if not self.size and not self.fixed_size:
@@ -250,7 +254,7 @@ class Partition():
 
         prefix = "ext" if self.fstype.startswith("ext") else self.fstype
         method = getattr(self, "prepare_rootfs_" + prefix)
-        method(rootfs, oe_builddir, rootfs_dir, native_sysroot, pseudo)
+        method(rootfs, cr_workdir, oe_builddir, rootfs_dir, native_sysroot, pseudo)
         self.source_file = rootfs
 
         # get the rootfs size in the right units for kickstart (kB)
@@ -258,7 +262,7 @@ class Partition():
         out = exec_cmd(du_cmd)
         self.size = int(out.split()[0])
 
-    def prepare_rootfs_ext(self, rootfs, oe_builddir, rootfs_dir,
+    def prepare_rootfs_ext(self, rootfs, cr_workdir, oe_builddir, rootfs_dir,
                            native_sysroot, pseudo):
         """
         Prepare content for an ext2/3/4 rootfs partition.
@@ -282,10 +286,19 @@ class Partition():
             (self.fstype, extraopts, rootfs, label_str, self.fsuuid, rootfs_dir)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
+        if self.updated_fstab_path and self.has_fstab:
+            debugfs_script_path = os.path.join(cr_workdir, "debugfs_script")
+            with open(debugfs_script_path, "w") as f:
+                f.write("cd etc\n")
+                f.write("rm fstab\n")
+                f.write("write %s fstab\n" % (self.updated_fstab_path))
+            debugfs_cmd = "debugfs -w -f %s %s" % (debugfs_script_path, rootfs)
+            exec_native_cmd(debugfs_cmd, native_sysroot)
+
         mkfs_cmd = "fsck.%s -pvfD %s" % (self.fstype, rootfs)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
-    def prepare_rootfs_btrfs(self, rootfs, oe_builddir, rootfs_dir,
+    def prepare_rootfs_btrfs(self, rootfs, cr_workdir, oe_builddir, rootfs_dir,
                              native_sysroot, pseudo):
         """
         Prepare content for a btrfs rootfs partition.
@@ -308,7 +321,7 @@ class Partition():
              self.mkfs_extraopts, self.fsuuid, rootfs)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
-    def prepare_rootfs_msdos(self, rootfs, oe_builddir, rootfs_dir,
+    def prepare_rootfs_msdos(self, rootfs, cr_workdir, oe_builddir, rootfs_dir,
                              native_sysroot, pseudo):
         """
         Prepare content for a msdos/vfat rootfs partition.
@@ -337,12 +350,16 @@ class Partition():
         mcopy_cmd = "mcopy -i %s -s %s/* ::/" % (rootfs, rootfs_dir)
         exec_native_cmd(mcopy_cmd, native_sysroot)
 
+        if self.updated_fstab_path and self.has_fstab:
+            mcopy_cmd = "mcopy -i %s %s ::/etc/fstab" % (rootfs, self.updated_fstab_path)
+            exec_native_cmd(mcopy_cmd, native_sysroot)
+
         chmod_cmd = "chmod 644 %s" % rootfs
         exec_cmd(chmod_cmd)
 
     prepare_rootfs_vfat = prepare_rootfs_msdos
 
-    def prepare_rootfs_squashfs(self, rootfs, oe_builddir, rootfs_dir,
+    def prepare_rootfs_squashfs(self, rootfs, cr_workdir, oe_builddir, rootfs_dir,
                                 native_sysroot, pseudo):
         """
         Prepare content for a squashfs rootfs partition.