virt-df: Match output with native (coreutils) 'df' command (RHBZ#578123).

This commit fixes the 'Use%' field in the output so it matches what
coreutils' 'df' command would print.

Firstly we change the calculation to use the space available to root,
not the space available to non-root.  This means it matches what 'df'
when run as root in the guest would show.

Secondly we display this rounded up to the next whole percent (ie. using
ceil), which is also what 'df' does.

Thirdly we change the regression test so it tests this.

Note that even with these changes you are not guaranteed to get precisely
the same figures from inside and outside the guest, as it depends on
how quiescent the guest is and how recently the superblock was synced.

Thanks: Rita Wu

1 files changed, 31 insertions, 5 deletions

diff --git a/tools/test-virt-df.sh b/tools/test-virt-df.sh
index 8e610632..a7b50b8f 100755
--- a/tools/test-virt-df.sh
+++ b/tools/test-virt-df.sh
@@ -4,13 +4,10 @@ export LANG=C
 set -e
 
 # Run virt-df.
-output=$(./virt-df test.img -h)
-
-# The output will be slightly different from one machine to another.
-# So just do some tests to make sure it looks reasonable.
+output=$(./virt-df test.img)
 
 # Check title is the first line.
-if [[ ! $output =~ ^Filesystem[[:space:]]+Size[[:space:]]+Used[[:space:]]+Available[[:space:]]+Use% ]]; then
+if [[ ! $output =~ ^Filesystem.* ]]; then
     echo "$0: error: no title line"
     exit 1
 fi
@@ -44,3 +41,32 @@ if [[ ! $output =~ test.img:/dev/[hsv]da1 ]]; then
     echo "$0: error: filesystem /dev/VG/sda1 was not found"
     exit 1
 fi
+
+# This is what df itself prints for these filesystems (determined
+# by running the test image under virt-rescue):
+#
+# ><rescue> df -h
+# Filesystem            Size  Used Avail Use% Mounted on
+# /dev/dm-1              31M   28K   30M   1% /sysroot/lv1
+# /dev/dm-2              31M  395K   29M   2% /sysroot/lv2
+# /dev/dm-3              62M  144K   59M   1% /sysroot/lv3
+# ><rescue> df -i
+# Filesystem            Inodes   IUsed   IFree IUse% Mounted on
+# /dev/dm-1               8192      11    8181    1% /sysroot/lv1
+# /dev/dm-2               8192      11    8181    1% /sysroot/lv2
+# /dev/dm-3              16384      11   16373    1% /sysroot/lv3
+# ><rescue> df
+# Filesystem           1K-blocks      Used Available Use% Mounted on
+# /dev/dm-1                31728        28     30064   1% /sysroot/lv1
+# /dev/dm-2                31729       395     29696   2% /sysroot/lv2
+# /dev/dm-3                63472       144     60052   1% /sysroot/lv3
+#
+# Only test plain 'df' output at the moment (XXX).
+
+if [ "$(echo "$output" | sort | awk '/VG.LV[123]/ { print $2 " " $3 " " $4 " " $5 }')" != \
+"31728 28 30064 1%
+31729 395 29696 2%
+63472 144 60052 1%" ]; then
+    echo "$0: error: output of virt-df did not match expected (df) output"
+    exit 1
+fi