On 9/25/19 1:32 PM, Max Reitz wrote:
And by that I mean all XFS versions, as far as I can tell. All details
are in the comment below.
We never noticed this problem because we only read the first number from
qemu-img info's "disk size" output -- and that is effectively useless,
because qemu-img prints a human-readable value (which generally includes
a decimal point). That will be fixed in the next patch.
Signed-off-by: Max Reitz <mre...@redhat.com>
---
tests/qemu-iotests/125 | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/tests/qemu-iotests/125 b/tests/qemu-iotests/125
index df328a63a6..0ef51f1e21 100755
--- a/tests/qemu-iotests/125
+++ b/tests/qemu-iotests/125
@@ -49,6 +49,46 @@ if [ -z "$TEST_IMG_FILE" ]; then
TEST_IMG_FILE=$TEST_IMG
fi
+# Test whether we are running on a broken XFS version. There is this
+# bug:
+
+# $ rm -f foo
+# $ touch foo
+# $ block_size=4096 # Your FS's block size
+# $ fallocate -o $((block_size / 2)) -l $block_size foo
+# $ LANG=C xfs_bmap foo | grep hole
+# 1: [8..15]: hole
+#
+# The problem is that the XFS driver rounds down the offset and
+# rounds up the length to the block size, but independently.
Eww. I concur you uncovered a bug. Have you reported this to xfs folks?
+
+touch "$TEST_IMG_FILE"
+# Assuming there is no FS with a block size greater than 64k
+fallocate -o 65535 -l 2 "$TEST_IMG_FILE"
+len0=$(get_image_size_on_host)
+
+# Write to something that in theory we have just fallocated
+# (Thus, the on-disk size should not increase)
+poke_file "$TEST_IMG_FILE" 65536 42
+len1=$(get_image_size_on_host)
+
+if [ $len1 -gt $len0 ]; then
+ _notrun "the test filesystem's fallocate() is broken"
+fi
+
+rm -f "$TEST_IMG_FILE"
Reviewed-by: Eric Blake <ebl...@redhat.com>
+
# Generally, we create some image with or without existing preallocation and
# then resize it. Then we write some data into the image and verify that its
# size does not change if we have used preallocation.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
