[Qemu-devel] [PULL 0/3] Block patches for 1.2-rc2

[Qemu-devel] [PULL 0/3] Block patches for 1.2-rc2

[Kevin Wolf]

The following changes since commit 18fec301cd2a38f72a5eeba2656a0c5b4fa69fb7:

  tcg/mips: fix broken CONFIG_TCG_PASS_AREG0 code (2012-08-28 20:38:39 +0200)

are available in the git repository at:
  http://repo.or.cz/r/qemu/kevin.git for-anthony

Stefan Hajnoczi (3):
      qed: refuse unaligned zero writes with a backing file
      stream: complete early if end of backing file is reached
      qemu-iotests: add backing file smaller than image test case

 block/qed.c                |   11 +++++++++++
 block/stream.c             |    6 ++++++
 tests/qemu-iotests/030     |   33 +++++++++++++++++++++++++++++++++
 tests/qemu-iotests/030.out |    4 ++--
 4 files changed, 52 insertions(+), 2 deletions(-)

[Qemu-devel] [PATCH 1/3] qed: refuse unaligned zero writes with a backing file

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Zero writes have cluster granularity in QED.  Therefore they can only be
used to zero entire clusters.

If the zero write request leaves sectors untouched, zeroing the entire
cluster would obscure the backing file.  Instead return -ENOTSUP, which
is handled by block.c:bdrv_co_do_write_zeroes() and falls back to a
regular write.

The qemu-iotests 034 test cases covers this scenario.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qed.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/block/qed.c b/block/qed.c
index a02dbfd..21cb239 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1363,10 +1363,21 @@ static int coroutine_fn bdrv_qed_co_write_zeroes(BlockDriverState *bs,
                                                  int nb_sectors)
 {
     BlockDriverAIOCB *blockacb;
+    BDRVQEDState *s = bs->opaque;
     QEDWriteZeroesCB cb = { .done = false };
     QEMUIOVector qiov;
     struct iovec iov;
 
+    /* Refuse if there are untouched backing file sectors */
+    if (bs->backing_hd) {
+        if (qed_offset_into_cluster(s, sector_num * BDRV_SECTOR_SIZE) != 0) {
+            return -ENOTSUP;
+        }
+        if (qed_offset_into_cluster(s, nb_sectors * BDRV_SECTOR_SIZE) != 0) {
+            return -ENOTSUP;
+        }
+    }
+
     /* Zero writes start without an I/O buffer.  If a buffer becomes necessary
      * then it will be allocated during request processing.
      */
-- 
1.7.6.5

[Qemu-devel] [PATCH 2/3] stream: complete early if end of backing file is reached

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

It is possible to create an image that is larger than its backing file.
Reading beyond the end of the backing file produces zeroes if no writes
have been made to those sectors in the image file.

This patch finishes streaming early when the end of the backing file is
reached.  Without this patch the block job hangs and continually tries
to stream the first sectors beyond the end of the backing file.

To reproduce the hung block job bug:

  $ qemu-img create -f qcow2 backing.qcow2 128M
  $ qemu-img create -f qcow2 -o backing_file=backing.qcow2 image.qcow2 6G
  $ qemu -drive if=virtio,cache=none,file=image.qcow2
  (qemu) block_stream virtio0
  (qemu) info block-jobs

The qemu-iotests 030 streaming test still passes.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/stream.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index 37c4652..c4f87dd 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -122,6 +122,12 @@ wait:
              * known-unallocated area [sector_num, sector_num+n).  */
             ret = bdrv_co_is_allocated_above(bs->backing_hd, base,
                                              sector_num, n, &n);
+
+            /* Finish early if end of backing file has been reached */
+            if (ret == 0 && n == 0) {
+                n = end - sector_num;
+            }
+
             copy = (ret == 1);
         }
         trace_stream_one_iteration(s, sector_num, n, ret);
-- 
1.7.6.5

[Qemu-devel] [PATCH 3/3] qemu-iotests: add backing file smaller than image test case

[Kevin Wolf]

From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

This new test case checks that streaming completes successfully when the
backing file is smaller than the image file.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/030     |   33 +++++++++++++++++++++++++++++++++
 tests/qemu-iotests/030.out |    4 ++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/030 b/tests/qemu-iotests/030
index f71ab8d..55b16f8 100755
--- a/tests/qemu-iotests/030
+++ b/tests/qemu-iotests/030
@@ -125,6 +125,39 @@ class TestSingleDrive(ImageStreamingTestCase):
         result = self.vm.qmp('block-stream', device='nonexistent')
         self.assert_qmp(result, 'error/class', 'DeviceNotFound')
 
+
+class TestSmallerBackingFile(ImageStreamingTestCase):
+    backing_len = 1 * 1024 * 1024 # MB
+    image_len = 2 * backing_len
+
+    def setUp(self):
+        self.create_image(backing_img, self.backing_len)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, test_img, str(self.image_len))
+        self.vm = iotests.VM().add_drive(test_img)
+        self.vm.launch()
+
+    # If this hangs, then you are missing a fix to complete streaming when the
+    # end of the backing file is reached.
+    def test_stream(self):
+        self.assert_no_active_streams()
+
+        result = self.vm.qmp('block-stream', device='drive0')
+        self.assert_qmp(result, 'return', {})
+
+        completed = False
+        while not completed:
+            for event in self.vm.get_qmp_events(wait=True):
+                if event['event'] == 'BLOCK_JOB_COMPLETED':
+                    self.assert_qmp(event, 'data/type', 'stream')
+                    self.assert_qmp(event, 'data/device', 'drive0')
+                    self.assert_qmp(event, 'data/offset', self.image_len)
+                    self.assert_qmp(event, 'data/len', self.image_len)
+                    completed = True
+
+        self.assert_no_active_streams()
+        self.vm.shutdown()
+
+
 class TestStreamStop(ImageStreamingTestCase):
     image_len = 8 * 1024 * 1024 * 1024 # GB
 
diff --git a/tests/qemu-iotests/030.out b/tests/qemu-iotests/030.out
index 3f8a935..2f7d390 100644
--- a/tests/qemu-iotests/030.out
+++ b/tests/qemu-iotests/030.out
@@ -1,5 +1,5 @@
-......
+.......
 ----------------------------------------------------------------------
-Ran 6 tests
+Ran 7 tests
 
 OK
-- 
1.7.6.5