diff options
| -rwxr-xr-x | tests/qemu-iotests/125 | 40 |
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. |