Bug#984584: initramfs-tools: autopkgtest amd64-separate-usr fails if TMPDIR is a tmpfs

[Sebastien Delafond <seb@debian.org>]

Source: initramfs-tools
Version: 0.139
Severity: normal
Tags: patch
User: devel@kali.org
Usertags: origin-kali

Here's the trace for the failing function build_fs_ext2, with
AUTOPKGTEST_TMP set to /srv/debci/tmp (a tmpfs with 1G of space):

  + local dir=/srv/debci/tmp/autopkgtest-lxc.nn7bbe1e/downtmp/autopkgtest_tmp/tmp.HkBCFUgax2
  + local disk=/tmp/tmp.1nt6IKxArY
  ++ cut -f 1
  ++ du --summarize /srv/debci/tmp/autopkgtest-lxc.nn7bbe1e/downtmp/autopkgtest_tmp/tmp.HkBCFUgax2
  + local blocks=0
  ++ du --summarize --inodes /srv/debci/tmp/autopkgtest-lxc.nn7bbe1e/downtmp/autopkgtest_tmp/tmp.HkBCFUgax2
  ++ cut -f 1
  + local inodes=2
  + blocks=20
  + inodes=12
  + genext2fs -b 20 -N 12 -U -d /srv/debci/tmp/autopkgtest-lxc.nn7bbe1e/downtmp/autopkgtest_tmp/tmp.HkBCFUgax2 /tmp/tmp.1nt6IKxArY
  genext2fs: couldn't allocate a block (no free space)

With AUTOPKGTEST_TMP unset, and mktemp therefore defaulting to a regular
ext4 /tmp, build_fs_ext2 succeeds:

  + local dir=/tmp/tmp.gs4fkyf68p
  + local disk=/tmp/tmp.NGXxR76wmo
  ++ cut -f 1
  ++ du --summarize /tmp/tmp.gs4fkyf68p
  + local blocks=8
  ++ cut -f 1
  ++ du --summarize --inodes /tmp/tmp.gs4fkyf68p
  + local inodes=2
  + blocks=30
  + inodes=12
  + genext2fs -b 30 -N 12 -U -d /tmp/tmp.gs4fkyf68p /tmp/tmp.NGXxR76wmo
  copying from directory /tmp/tmp.gs4fkyf68p
  + grep -q '^/dev/vda: clean,' /tmp/tmp.RB4hnjbtNn

`du --summarize` is clearly having issues calculating the number of
blocks in the tmpfs case, so this could possibly instead be a du
problem, but since build_fs_ext2 is adding a bit of fudge factor to that
result later down the line, my current patch is as follows:

--- debian/tests/test-common.bak	2021-03-05 12:55:18.734702358 +0000
+++ debian/tests/test-common	2021-03-05 13:06:49.340274568 +0000
@@ -72,7 +72,7 @@
 	local inodes="$(du --summarize --inodes "${dir}" | cut -f 1)"
 
 	# Add fudge factor
-        blocks="$((blocks + 20 + blocks / 4))"
+        blocks="$((blocks + 28 + blocks / 4))"
         inodes="$((inodes + 10))"
 
 	# genext2fs writes status messages to stderr; hide that from

With this patch in place, the amd64-separate-usr test then succeeds for
both tmpfs and ext4.

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-3-amd64 (SMP w/36 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled