[Qemu-devel] [PATCH v3 2/2] iotests: Test allocate_first_block() with O_DIRECT

[Nir Soffer <nirsof@gmail.com>]

Using block_resize we can test allocate_first_block() with file
descriptor opened with O_DIRECT, ensuring that it works for any size
larger than 4096 bytes.

Testing smaller sizes is tricky as the result depends on the filesystem
used for testing. For example on NFS any size will work since O_DIRECT
does not require any alignment.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/175     | 28 ++++++++++++++++++++++++++++
 tests/qemu-iotests/175.out |  8 ++++++++
 2 files changed, 36 insertions(+)

diff --git a/tests/qemu-iotests/175 b/tests/qemu-iotests/175
index 7ba28b3c1b..55db2803ed 100755
--- a/tests/qemu-iotests/175
+++ b/tests/qemu-iotests/175
@@ -49,6 +49,23 @@ _filter_blocks()
         -e "s/blocks=$((extra_blocks + img_size / 512))\\(\$\\|[^0-9]\\)/max allocation/"
 }
 
+# Resize image using block_resize.
+# Parameter 1: image path
+# Parameter 2: new size
+_block_resize()
+{
+    local path=$1
+    local size=$2
+
+    $QEMU -qmp stdio -nographic -nodefaults \
+        -blockdev file,node-name=file,filename=$path,cache.direct=on \
+        <<EOF
+{'execute': 'qmp_capabilities'}
+{'execute': 'block_resize', 'arguments': {'node-name': 'file', 'size': $size}}
+{'execute': 'quit'}
+EOF
+}
+
 # get standard environment, filters and checks
 . ./common.rc
 . ./common.filter
@@ -57,6 +74,9 @@ _supported_fmt raw
 _supported_proto file
 _supported_os Linux
 
+_default_cache_mode none
+_supported_cache_modes none directsync
+
 size=$((1 * 1024 * 1024))
 
 touch "$TEST_DIR/empty"
@@ -79,6 +99,14 @@ for mode in off full falloc; do
     stat -c "size=%s, blocks=%b" $TEST_IMG | _filter_blocks $extra_blocks $min_blocks $size
 done
 
+for new_size in 4096 1048576; do
+    echo
+    echo "== resize empty image with block_resize =="
+    _make_test_img 0 | _filter_imgfmt
+    _block_resize $TEST_IMG $new_size >/dev/null
+    stat -c "size=%s, blocks=%b" $TEST_IMG | _filter_blocks $extra_blocks $min_blocks $new_size
+done
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/175.out b/tests/qemu-iotests/175.out
index 263e521262..39c2ee0f62 100644
--- a/tests/qemu-iotests/175.out
+++ b/tests/qemu-iotests/175.out
@@ -15,4 +15,12 @@ size=1048576, max allocation
 == creating image with preallocation falloc ==
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 preallocation=falloc
 size=1048576, max allocation
+
+== resize empty image with block_resize ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=0
+size=4096, min allocation
+
+== resize empty image with block_resize ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=0
+size=1048576, min allocation
  *** done
-- 
2.20.1