aboutsummaryrefslogtreecommitdiff
path: root/tests
diff options
context:
space:
mode:
authorMax Reitz <mreitz@redhat.com>2019-09-25 20:32:30 +0200
committerMax Reitz <mreitz@redhat.com>2019-10-10 10:56:18 +0200
commit285f595d74738f9f99c5b5b05005956e0d7c1b77 (patch)
treeafa8319f27725ea23e9e4e11ad4296b913661250 /tests
parente6e8db0337307eb600d0903adea44eaa7ff14cc3 (diff)
iotests: Disable 125 on broken XFS versions
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 <mreitz@redhat.com> Message-id: 20190925183231.11196-3-mreitz@redhat.com Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'tests')
-rwxr-xr-xtests/qemu-iotests/12540
1 files changed, 40 insertions, 0 deletions
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. As
+# such, it only allocates the first block in the example above,
+# even though it should allocate the first two blocks (because our
+# request is to fallocate something that touches both the first
+# two blocks).
+#
+# This means that when you then write to the beginning of the
+# second block, the disk usage of the first two blocks grows.
+#
+# That is precisely what fallocate() promises, though: That when you
+# write to an area that you have fallocated, no new blocks will have
+# to be allocated.
+
+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"
+
# 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.