[PATCH] iotests: don't run tests requiring cached writes in '-nocache' mode

[Andrey Drobyshev]

There're tests whose logic implies running without O_DIRECT set,
otherwise they fail when running iotests in '-nocache' mode.  For these
tests let's add _require_no_o_direct() helper which can be put in the
preabmle and which makes sure '-nocache' isn't set.  Use it to skip
running the following tests:

  * 271: creates files with unaligned sizes, thus producing multiple
    errors like:

qemu-io: can't open device /path/to/t.qcow2.raw: Cannot get 'write'
permission without 'resize': Image size is not a multiple of request alignment

  * 308, file-io-error: use fuse exports.  Though fuse does have
    'direct-io' mode (see https://docs.kernel.org/filesystems/fuse-io.html)
    we aren't using it yet, thus getting errors like:

qemu-io: can't open device /path/to/t.qcow2.fuse: Could not open
'/path/to/t.qcow2.fuse': filesystem does not support O_DIRECT

Signed-off-by: Andrey Drobyshev <andrey.drobys...@virtuozzo.com>
---
 tests/qemu-iotests/271                 | 1 +
 tests/qemu-iotests/308                 | 2 ++
 tests/qemu-iotests/common.rc           | 7 +++++++
 tests/qemu-iotests/tests/file-io-error | 1 +
 4 files changed, 11 insertions(+)

diff --git a/tests/qemu-iotests/271 b/tests/qemu-iotests/271
index 59a6fafa2f..1424b6954d 100755
--- a/tests/qemu-iotests/271
+++ b/tests/qemu-iotests/271
@@ -44,6 +44,7 @@ _supported_fmt qcow2
 _supported_proto file nfs
 _supported_os Linux
 _unsupported_imgopts extended_l2 compat=0.10 cluster_size data_file 
refcount_bits=1[^0-9]
+_require_no_o_direct
 
 l2_offset=$((0x40000))
 
diff --git a/tests/qemu-iotests/308 b/tests/qemu-iotests/308
index de12b2b1b9..535455e5b1 100755
--- a/tests/qemu-iotests/308
+++ b/tests/qemu-iotests/308
@@ -52,6 +52,8 @@ _unsupported_fmt vpc
 _supported_proto file # We create the FUSE export manually
 _supported_os Linux # We need /dev/urandom
 
+_require_no_o_direct
+
 # $1: Export ID
 # $2: Options (beyond the node-name and ID)
 # $3: Expected return value (defaults to 'return')
diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index 95c12577dd..f61eae73b4 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -857,6 +857,13 @@ _check_o_direct()
     [[ "$out" != *"O_DIRECT"* ]]
 }
 
+_require_no_o_direct()
+{
+    if [ $CACHEMODE == "none" ] || [ $CACHEMODE == "directsync" ]; then
+        _notrun "not suitable for cache mode: $CACHEMODE (implies O_DIRECT)"
+    fi
+}
+
 _require_o_direct()
 {
     if ! _check_o_direct; then
diff --git a/tests/qemu-iotests/tests/file-io-error 
b/tests/qemu-iotests/tests/file-io-error
index 88ee5f670c..2b8dc7f009 100755
--- a/tests/qemu-iotests/tests/file-io-error
+++ b/tests/qemu-iotests/tests/file-io-error
@@ -40,6 +40,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 # Format-agnostic (we do not use any), but we do test the file protocol
 _supported_proto file
 _require_drivers blkdebug null-co
+_require_no_o_direct
 
 if [ "$IMGOPTSSYNTAX" = "true" ]; then
     # We need `$QEMU_IO -f file` to work; IMGOPTSSYNTAX uses --image-opts,
-- 
2.39.3