[PATCH 0/3] mirror: Make sure that source and target size match

[PATCH 0/3] mirror: Make sure that source and target size match

[Kevin Wolf]

Same thing as the recent fix for backup, except that mirror already
forbids resizing during the job. So what remains is checking that the
sizes match at the start of the job.

Kevin Wolf (3):
  iotests/229: Use blkdebug to inject an error
  mirror: Make sure that source and target size match
  iotests: Mirror with different source/target size

 block/mirror.c             | 21 ++++++++++--------
 tests/qemu-iotests/041     | 45 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/041.out |  4 ++--
 tests/qemu-iotests/229     | 15 +++++++++----
 tests/qemu-iotests/229.out |  6 ++---
 5 files changed, 73 insertions(+), 18 deletions(-)

-- 
2.25.3

[PATCH 1/3] iotests/229: Use blkdebug to inject an error

[Kevin Wolf]

229 relies on the mirror running into an I/O error when the target is
smaller than the source. After changing mirror to catch this condition
while starting the job, this test case won't get a job that is paused
for an I/O error any more. Use blkdebug instead to inject an error.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/229     | 15 +++++++++++----
 tests/qemu-iotests/229.out |  6 +++---
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/tests/qemu-iotests/229 b/tests/qemu-iotests/229
index 866168b236..a5d4e5d4f2 100755
--- a/tests/qemu-iotests/229
+++ b/tests/qemu-iotests/229
@@ -33,6 +33,7 @@ _cleanup()
     _cleanup_test_img
     _rm_test_img "$TEST_IMG"
     _rm_test_img "$DEST_IMG"
+    rm -f "$TEST_DIR/blkdebug.conf"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
@@ -49,11 +50,10 @@ _supported_os Linux
 
 DEST_IMG="$TEST_DIR/d.$IMGFMT"
 TEST_IMG="$TEST_DIR/b.$IMGFMT"
+BLKDEBUG_CONF="$TEST_DIR/blkdebug.conf"
 
 _make_test_img 2M
-
-# destination for mirror will be too small, causing error
-TEST_IMG=$DEST_IMG _make_test_img 1M
+TEST_IMG=$DEST_IMG _make_test_img 2M
 
 $QEMU_IO -c 'write 0 2M' "$TEST_IMG" | _filter_qemu_io
 
@@ -67,11 +67,18 @@ echo
 echo '=== Starting drive-mirror, causing error & stop  ==='
 echo
 
+cat > "$BLKDEBUG_CONF" <<EOF
+[inject-error]
+event = "write_aio"
+errno = "5"
+once = "on"
+EOF
+
 _send_qemu_cmd $QEMU_HANDLE \
     "{'execute': 'drive-mirror',
                  'arguments': {'device': 'testdisk',
                                'format': '$IMGFMT',
-                               'target': '$DEST_IMG',
+                               'target': 'blkdebug:$BLKDEBUG_CONF:$DEST_IMG',
                                'sync':   'full',
                                'mode':   'existing',
                                'on-source-error': 'stop',
diff --git a/tests/qemu-iotests/229.out b/tests/qemu-iotests/229.out
index 22350d75d7..fdcd249642 100644
--- a/tests/qemu-iotests/229.out
+++ b/tests/qemu-iotests/229.out
@@ -1,6 +1,6 @@
 QA output created by 229
 Formatting 'TEST_DIR/b.IMGFMT', fmt=IMGFMT size=2097152
-Formatting 'TEST_DIR/d.IMGFMT', fmt=IMGFMT size=1048576
+Formatting 'TEST_DIR/d.IMGFMT', fmt=IMGFMT size=2097152
 wrote 2097152/2097152 bytes at offset 0
 2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {'execute': 'qmp_capabilities'}
@@ -8,7 +8,7 @@ wrote 2097152/2097152 bytes at offset 0
 
 === Starting drive-mirror, causing error & stop  ===
 
-{'execute': 'drive-mirror', 'arguments': {'device': 'testdisk', 'format': 'IMGFMT', 'target': 'TEST_DIR/d.IMGFMT', 'sync': 'full', 'mode': 'existing', 'on-source-error': 'stop', 'on-target-error': 'stop' }}
+{'execute': 'drive-mirror', 'arguments': {'device': 'testdisk', 'format': 'IMGFMT', 'target': 'blkdebug:TEST_DIR/blkdebug.conf:TEST_DIR/d.IMGFMT', 'sync': 'full', 'mode': 'existing', 'on-source-error': 'stop', 'on-target-error': 'stop' }}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "created", "id": "testdisk"}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "testdisk"}}
 {"return": {}}
@@ -21,5 +21,5 @@ wrote 2097152/2097152 bytes at offset 0
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "running", "id": "testdisk"}}
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "JOB_STATUS_CHANGE", "data": {"status": "aborting", "id": "testdisk"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_CANCELLED", "data": {"device": "testdisk", "len": 2097152, "offset": 1048576, "speed": 0, "type": "mirror"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_CANCELLED", "data": {"device": "testdisk", "len": 2097152, "offset": 2097152, "speed": 0, "type": "mirror"}}
 *** done
-- 
2.25.3

[PATCH 2/3] mirror: Make sure that source and target size match

[Kevin Wolf]

If the target is shorter than the source, mirror would copy data until
it reaches the end of the target and then fail with an I/O error when
trying to write past the end.

If the target is longer than the source, the mirror job would complete
successfully, but the target wouldn't actually be an accurate copy of
the source image (it would contain some additional garbage at the end).

Fix this by checking that both images have the same size when the job
starts.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/mirror.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index aca95c9bc9..201ffa26f9 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -872,6 +872,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
     BlockDriverState *target_bs = blk_bs(s->target);
     bool need_drain = true;
     int64_t length;
+    int64_t target_length;
     BlockDriverInfo bdi;
     char backing_filename[2]; /* we only need 2 characters because we are only
                                  checking for a NULL string */
@@ -887,24 +888,26 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
         goto immediate_exit;
     }
 
+    target_length = blk_getlength(s->target);
+    if (target_length < 0) {
+        ret = target_length;
+        goto immediate_exit;
+    }
+
     /* Active commit must resize the base image if its size differs from the
      * active layer. */
     if (s->base == blk_bs(s->target)) {
-        int64_t base_length;
-
-        base_length = blk_getlength(s->target);
-        if (base_length < 0) {
-            ret = base_length;
-            goto immediate_exit;
-        }
-
-        if (s->bdev_length > base_length) {
+        if (s->bdev_length > target_length) {
             ret = blk_truncate(s->target, s->bdev_length, false,
                                PREALLOC_MODE_OFF, 0, NULL);
             if (ret < 0) {
                 goto immediate_exit;
             }
         }
+    } else if (s->bdev_length != target_length) {
+        error_setg(errp, "Source and target image have different sizes");
+        ret = -EINVAL;
+        goto immediate_exit;
     }
 
     if (s->bdev_length == 0) {
-- 
2.25.3

[PATCH 3/3] iotests: Mirror with different source/target size

[Kevin Wolf]

This tests that the mirror job catches situations where the target node
has a different size than the source node. It must also forbid resize
operations when the job is already running.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/041     | 45 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/041.out |  4 ++--
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 1812dd8479..601c756117 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -240,6 +240,49 @@ class TestSingleBlockdev(TestSingleDrive):
                              target=self.qmp_target)
         self.assert_qmp(result, 'error/class', 'GenericError')
 
+    def do_test_resize(self, device, node):
+        def pre_finalize():
+            if device:
+                result = self.vm.qmp('block_resize', device=device, size=65536)
+                self.assert_qmp(result, 'error/class', 'GenericError')
+
+            result = self.vm.qmp('block_resize', node_name=node, size=65536)
+            self.assert_qmp(result, 'error/class', 'GenericError')
+
+        result = self.vm.qmp(self.qmp_cmd, job_id='job0', device='drive0',
+                             sync='full', target=self.qmp_target,
+                             auto_finalize=False, auto_dismiss=False)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.run_job('job0', auto_finalize=False,
+                                 pre_finalize=pre_finalize)
+        self.assertEqual(result, None)
+
+    def test_source_resize(self):
+        self.do_test_resize('drive0', 'top')
+
+    def test_target_resize(self):
+        self.do_test_resize(None, self.qmp_target)
+
+    def do_test_target_size(self, size):
+        result = self.vm.qmp('block_resize', node_name=self.qmp_target,
+                             size=size)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp(self.qmp_cmd, job_id='job0',
+                             device='drive0', sync='full', auto_dismiss=False,
+                             target=self.qmp_target)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.run_job('job0')
+        self.assertEqual(result, 'Source and target image have different sizes')
+
+    def test_small_target(self):
+        self.do_test_target_size(self.image_len // 2)
+
+    def test_large_target(self):
+        self.do_test_target_size(self.image_len * 2)
+
     test_large_cluster = None
     test_image_not_found = None
     test_small_buffer2 = None
@@ -251,6 +294,8 @@ class TestSingleDriveZeroLength(TestSingleDrive):
 
 class TestSingleBlockdevZeroLength(TestSingleBlockdev):
     image_len = 0
+    test_small_target = None
+    test_large_target = None
 
 class TestSingleDriveUnalignedLength(TestSingleDrive):
     image_len = 1025 * 1024
diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
index 877b76fd31..53abe11d73 100644
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-..............................................................................................
+........................................................................................................
 ----------------------------------------------------------------------
-Ran 94 tests
+Ran 104 tests
 
 OK
-- 
2.25.3

Re: [PATCH 1/3] iotests/229: Use blkdebug to inject an error

[Eric Blake]

On 5/7/20 9:52 AM, Kevin Wolf wrote:
> 229 relies on the mirror running into an I/O error when the target is
> smaller than the source. After changing mirror to catch this condition
> while starting the job, this test case won't get a job that is paused
> for an I/O error any more. Use blkdebug instead to inject an error.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   tests/qemu-iotests/229     | 15 +++++++++++----
>   tests/qemu-iotests/229.out |  6 +++---
>   2 files changed, 14 insertions(+), 7 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH 2/3] mirror: Make sure that source and target size match

[Eric Blake]

On 5/7/20 9:52 AM, Kevin Wolf wrote:
> If the target is shorter than the source, mirror would copy data until
> it reaches the end of the target and then fail with an I/O error when
> trying to write past the end.
> 
> If the target is longer than the source, the mirror job would complete
> successfully, but the target wouldn't actually be an accurate copy of
> the source image (it would contain some additional garbage at the end).
> 
> Fix this by checking that both images have the same size when the job
> starts.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/mirror.c | 21 ++++++++++++---------
>   1 file changed, 12 insertions(+), 9 deletions(-)

An alternative would be trying to resize the target (like we have to do 
with active commit), but I'm fine with being conservative for now by 
forcing the user to have correct sizing, where we have the option to add 
magic resizing later only if it proves useful and not introducing more 
potential issues.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH 3/3] iotests: Mirror with different source/target size

[Eric Blake]

On 5/7/20 9:52 AM, Kevin Wolf wrote:
> This tests that the mirror job catches situations where the target node
> has a different size than the source node. It must also forbid resize
> operations when the job is already running.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   tests/qemu-iotests/041     | 45 ++++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/041.out |  4 ++--
>   2 files changed, 47 insertions(+), 2 deletions(-)
> 
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org