From ef72f76e58107bd4096018c3db2912d28249308e Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 28 Aug 2012 14:04:27 +0100 Subject: qed: refuse unaligned zero writes with a backing file 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 Reviewed-by: Paolo Bonzini Signed-off-by: Kevin Wolf --- block/qed.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/block/qed.c b/block/qed.c index a02dbfd72..21cb23987 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. */ -- cgit v1.2.3 From 571cd9dcc7f2fee59e47913365ced7781f33c2d3 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 28 Aug 2012 15:26:48 +0100 Subject: stream: complete early if end of backing file is reached 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 Reviewed-by: Paolo Bonzini Signed-off-by: Kevin Wolf --- block/stream.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/block/stream.c b/block/stream.c index 37c46525d..c4f87dd5b 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); -- cgit v1.2.3 From 774a8850d708aeb6dd6de493c28b374098c1a4c3 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 28 Aug 2012 15:26:49 +0100 Subject: qemu-iotests: add backing file smaller than image test case This new test case checks that streaming completes successfully when the backing file is smaller than the image file. Signed-off-by: Stefan Hajnoczi Reviewed-by: Paolo Bonzini Signed-off-by: Kevin Wolf --- 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 f71ab8dd1..55b16f81d 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 3f8a935a0..2f7d3902f 100644 --- a/tests/qemu-iotests/030.out +++ b/tests/qemu-iotests/030.out @@ -1,5 +1,5 @@ -...... +....... ---------------------------------------------------------------------- -Ran 6 tests +Ran 7 tests OK -- cgit v1.2.3