On 07/18/2016 03:17 PM, Denis V. Lunev wrote:
> On 07/18/2016 10:10 PM, John Snow wrote:
>>
>> On 07/15/2016 09:47 AM, Denis V. Lunev wrote:
>>> From: Evgeny Yakovlev <eyakov...@virtuozzo.com>
>>>
>>> Some guests (win2008 server for example) do a lot of unnecessary
>>> flushing when underlying media has not changed. This adds additional
>>> overhead on host when calling fsync/fdatasync.
>>>
>>> This change introduces a write generation scheme in BlockDriverState.
>>> Current write generation is checked against last flushed generation to
>>> avoid unnessesary flushes.
>>>
>>> The problem with excessive flushing was found by a performance test
>>> which does parallel directory tree creation (from 2 processes).
>>> Results improved from 0.424 loops/sec to 0.432 loops/sec.
>>> Each loop creates 10^3 directories with 10 files in each.
>>>
>>> This affected some blkdebug testcases that were expecting error logs
>>> from
>>> failure-injected flushes which are now skipped entirely
>>> (tests 026 071 089).
>>>
>>> This also affects the performance of block jobs and thus BLOCK_JOB_READY
>>> events for driver-mirror and active block-commit commands now arrives
>>> faster, before QMP send successfully returns to caller (tests 141 144).
>>>
>>> Signed-off-by: Evgeny Yakovlev <eyakov...@virtuozzo.com>
>>> Signed-off-by: Denis V. Lunev <d...@openvz.org>
>>> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
>>> CC: Kevin Wolf <kw...@redhat.com>
>>> CC: Max Reitz <mre...@redhat.com>
>>> CC: Stefan Hajnoczi <stefa...@redhat.com>
>>> CC: Fam Zheng <f...@redhat.com>
>>> CC: John Snow <js...@redhat.com>
>>> ---
>>> block.c | 3 +++
>>> block/io.c | 21 ++++++++++++++++
>>> include/block/block_int.h | 5 ++++
>>> tests/qemu-iotests/026.out.nocache | 50
>>> --------------------------------------
>>> tests/qemu-iotests/071.out | 8 ------
>>> tests/qemu-iotests/089.out | 2 --
>>> tests/qemu-iotests/141.out | 4 +--
>>> tests/qemu-iotests/144.out | 2 +-
>>> 8 files changed, 32 insertions(+), 63 deletions(-)
>>>
>>> diff --git a/block.c b/block.c
>>> index 823ff1d..060f88e 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -234,6 +234,8 @@ BlockDriverState *bdrv_new(void)
>>> bs->refcnt = 1;
>>> bs->aio_context = qemu_get_aio_context();
>>> + qemu_co_queue_init(&bs->flush_queue);
>>> +
>>> QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
>>> return bs;
>>> @@ -2472,6 +2474,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t
>>> offset)
>>> ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
>>> bdrv_dirty_bitmap_truncate(bs);
>>> bdrv_parent_cb_resize(bs);
>>> + ++bs->write_gen;
>>> }
>>> return ret;
>>> }
>>> diff --git a/block/io.c b/block/io.c
>>> index 7086908..f181ff7 100644
>>> --- a/block/io.c
>>> +++ b/block/io.c
>>> @@ -1303,6 +1303,7 @@ static int coroutine_fn
>>> bdrv_aligned_pwritev(BlockDriverState *bs,
>>> }
>>> bdrv_debug_event(bs, BLKDBG_PWRITEV_DONE);
>>> + ++bs->write_gen;
>>> bdrv_set_dirty(bs, start_sector, end_sector - start_sector);
>>> if (bs->wr_highest_offset < offset + bytes) {
>>> @@ -2235,6 +2236,15 @@ int coroutine_fn
>>> bdrv_co_flush(BlockDriverState *bs)
>>> tracked_request_begin(&req, bs, 0, 0, BDRV_TRACKED_FLUSH);
>>> + int current_gen = bs->write_gen;
>>> +
>>> + /* Wait until any previous flushes are completed */
>>> + while (bs->flush_started_gen != bs->flushed_gen) {
>>> + qemu_co_queue_wait(&bs->flush_queue);
>>> + }
>>> +
>>> + bs->flush_started_gen = current_gen;
>>> +
>>> /* Write back all layers by calling one driver function */
>>> if (bs->drv->bdrv_co_flush) {
>>> ret = bs->drv->bdrv_co_flush(bs);
>>> @@ -2255,6 +2265,11 @@ int coroutine_fn
>>> bdrv_co_flush(BlockDriverState *bs)
>>> goto flush_parent;
>>> }
>>> + /* Check if we really need to flush anything */
>>> + if (bs->flushed_gen == current_gen) {
>>> + goto flush_parent;
>>> + }
>>> +
>>> BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
>>> if (bs->drv->bdrv_co_flush_to_disk) {
>>> ret = bs->drv->bdrv_co_flush_to_disk(bs);
>>> @@ -2285,6 +2300,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState
>>> *bs)
>>> */
>>> ret = 0;
>>> }
>>> +
>>> if (ret < 0) {
>>> goto out;
>>> }
>>> @@ -2295,6 +2311,10 @@ int coroutine_fn
>>> bdrv_co_flush(BlockDriverState *bs)
>>> flush_parent:
>>> ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
>>> out:
>>> + /* Notify any pending flushes that we have completed */
>>> + bs->flushed_gen = current_gen;
>>> + qemu_co_queue_restart_all(&bs->flush_queue);
>>> +
>>> tracked_request_end(&req);
>>> return ret;
>>> }
>>> @@ -2420,6 +2440,7 @@ int coroutine_fn
>>> bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
>>> }
>>> ret = 0;
>>> out:
>>> + ++bs->write_gen;
>>> bdrv_set_dirty(bs, req.offset >> BDRV_SECTOR_BITS,
>>> req.bytes >> BDRV_SECTOR_BITS);
>>> tracked_request_end(&req);
>>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>>> index 47b9aac..396bd2b 100644
>>> --- a/include/block/block_int.h
>>> +++ b/include/block/block_int.h
>>> @@ -439,6 +439,11 @@ struct BlockDriverState {
>>> int copy_on_read; /* if nonzero, copy read backing sectors into
>>> image.
>>> note this is a reference count */
>>> + CoQueue flush_queue; /* Serializing flush queue */
>>> + unsigned int write_gen; /* Current data generation */
>>> + unsigned int flush_started_gen; /* Generation for which flush
>>> has started */
>>> + unsigned int flushed_gen; /* Flushed write generation */
>>> +
>>> BlockDriver *drv; /* NULL means no media */
>>> void *opaque;
>>> diff --git a/tests/qemu-iotests/026.out.nocache
>>> b/tests/qemu-iotests/026.out.nocache
>>> index 9c2c8a9..672d77c 100644
>>> --- a/tests/qemu-iotests/026.out.nocache
>>> +++ b/tests/qemu-iotests/026.out.nocache
>>> @@ -14,7 +14,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_update; errno: 5; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> @@ -23,7 +22,6 @@ This means waste of disk space, but no harm to data.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_update; errno: 5; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> @@ -42,7 +40,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_update; errno: 28; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -51,7 +48,6 @@ This means waste of disk space, but no harm to data.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_update; errno: 28; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -78,11 +74,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT
>>> size=1073741824
>>> Event: l2_load; errno: 5; imm: off; once: off; write
>>> wrote 131072/131072 bytes at offset 0
>>> 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> read failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -90,11 +82,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT
>>> size=1073741824
>>> Event: l2_load; errno: 5; imm: off; once: off; write -b
>>> wrote 131072/131072 bytes at offset 0
>>> 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> read failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -118,11 +106,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT
>>> size=1073741824
>>> Event: l2_load; errno: 28; imm: off; once: off; write
>>> wrote 131072/131072 bytes at offset 0
>>> 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> read failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -130,11 +114,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT
>>> size=1073741824
>>> Event: l2_load; errno: 28; imm: off; once: off; write -b
>>> wrote 131072/131072 bytes at offset 0
>>> 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> read failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -314,14 +294,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_load; errno: 5; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_load; errno: 5; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> @@ -338,14 +316,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_load; errno: 28; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_load; errno: 28; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> @@ -362,14 +338,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_update_part; errno: 5; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_update_part; errno: 5; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> @@ -386,14 +360,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_update_part; errno: 28; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_update_part; errno: 28; imm: off; once: off;
>>> write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> @@ -410,14 +382,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc; errno: 5; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc; errno: 5; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> @@ -434,14 +404,12 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc; errno: 28; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc; errno: 28; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> @@ -458,15 +426,11 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: cluster_alloc; errno: 5; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: cluster_alloc; errno: 5; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -482,15 +446,11 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: cluster_alloc; errno: 28; imm: off; once: off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: cluster_alloc; errno: 28; imm: off; once: off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> @@ -561,7 +521,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc_write_blocks; errno: 28; imm: off; once:
>>> off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -570,7 +529,6 @@ This means waste of disk space, but no harm to
>>> data.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc_write_blocks; errno: 28; imm: off; once:
>>> off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -589,7 +547,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc_write_table; errno: 28; imm: off; once:
>>> off; write
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -598,7 +555,6 @@ This means waste of disk space, but no harm to
>>> data.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: refblock_alloc_write_table; errno: 28; imm: off; once:
>>> off; write -b
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> @@ -643,8 +599,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_grow_alloc_table; errno: 5; imm: off; once: off
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -655,8 +609,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_grow_alloc_table; errno: 28; imm: off; once: off
>>> -Failed to flush the L2 table cache: No space left on device
>>> -Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> @@ -667,7 +619,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_grow_write_table; errno: 5; imm: off; once: off
>>> -Failed to flush the L2 table cache: Input/output error
>>> Failed to flush the refcount block cache: Input/output error
>>> write failed: Input/output error
>>> No errors were found on the image.
>>> @@ -679,7 +630,6 @@ No errors were found on the image.
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824
>>> Event: l1_grow_write_table; errno: 28; imm: off; once: off
>>> -Failed to flush the L2 table cache: No space left on device
>>> Failed to flush the refcount block cache: No space left on device
>>> write failed: No space left on device
>>> No errors were found on the image.
>>> diff --git a/tests/qemu-iotests/071.out b/tests/qemu-iotests/071.out
>>> index 2b40ead..8c6851e 100644
>>> --- a/tests/qemu-iotests/071.out
>>> +++ b/tests/qemu-iotests/071.out
>>> @@ -30,14 +30,10 @@ blkverify: read sector_num=0 nb_sectors=1
>>> contents mismatch in sector 0
>>> === Testing blkdebug through filename ===
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> read failed: Input/output error
>>> === Testing blkdebug through file blockref ===
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> read failed: Input/output error
>>> === Testing blkdebug on existing block device ===
>>> @@ -51,8 +47,6 @@ read failed: Input/output error
>>> {"return": ""}
>>> {"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "SHUTDOWN"}
>>> -QEMU_PROG: Failed to flush the L2 table cache: Input/output error
>>> -QEMU_PROG: Failed to flush the refcount block cache: Input/output error
>>> === Testing blkverify on existing block device ===
>>> @@ -92,7 +86,5 @@ read failed: Input/output error
>>> {"return": ""}
>>> {"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "SHUTDOWN"}
>>> -QEMU_PROG: Failed to flush the L2 table cache: Input/output error
>>> -QEMU_PROG: Failed to flush the refcount block cache: Input/output error
>>> *** done
>>> diff --git a/tests/qemu-iotests/089.out b/tests/qemu-iotests/089.out
>>> index 5b541a3..18f5fdd 100644
>>> --- a/tests/qemu-iotests/089.out
>>> +++ b/tests/qemu-iotests/089.out
>>> @@ -24,8 +24,6 @@ read 512/512 bytes at offset 0
>>> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>>> wrote 512/512 bytes at offset 229376
>>> 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>>> -Failed to flush the L2 table cache: Input/output error
>>> -Failed to flush the refcount block cache: Input/output error
>>> read failed: Input/output error
>>> === Testing qemu-img info output ===
>>> diff --git a/tests/qemu-iotests/141.out b/tests/qemu-iotests/141.out
>>> index adceac1..eaf1e60 100644
>>> --- a/tests/qemu-iotests/141.out
>>> +++ b/tests/qemu-iotests/141.out
>>> @@ -18,8 +18,8 @@ Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT
>>> size=1048576 backing_file=TEST_DIR/t.
>>> {"return": {}}
>>> Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT size=1048576
>>> backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
>>> -{"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_READY", "data": {"device": "drv0", "len": 0,
>>> "offset": 0, "speed": 0, "type": "mirror"}}
>>> +{"return": {}}
>>> {"error": {"class": "GenericError", "desc": "Node 'drv0' is busy:
>>> block device is in use by block job: mirror"}}
>>> {"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_COMPLETED", "data": {"device": "drv0", "len": 0,
>>> "offset": 0, "speed": 0, "type": "mirror"}}
>>> @@ -28,8 +28,8 @@ Formatting 'TEST_DIR/o.IMGFMT', fmt=IMGFMT
>>> size=1048576 backing_file=TEST_DIR/t.
>>> === Testing active block-commit ===
>>> {"return": {}}
>>> -{"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_READY", "data": {"device": "drv0", "len": 0,
>>> "offset": 0, "speed": 0, "type": "commit"}}
>>> +{"return": {}}
>>> {"error": {"class": "GenericError", "desc": "Node 'drv0' is busy:
>>> block device is in use by block job: commit"}}
>>> {"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_COMPLETED", "data": {"device": "drv0", "len": 0,
>>> "offset": 0, "speed": 0, "type": "commit"}}
>>> diff --git a/tests/qemu-iotests/144.out b/tests/qemu-iotests/144.out
>>> index 410d741..387855c 100644
>>> --- a/tests/qemu-iotests/144.out
>>> +++ b/tests/qemu-iotests/144.out
>>> @@ -12,9 +12,9 @@ Formatting 'TEST_DIR/tmp.qcow2', fmt=qcow2
>>> size=536870912 backing_file=TEST_DIR/
>>> === Performing block-commit on active layer ===
>>> -{"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_READY", "data": {"device": "virtio0", "len": 0,
>>> "offset": 0, "speed": 0, "type": "commit"}}
>>> {"return": {}}
>>> +{"return": {}}
>>> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_COMPLETED", "data": {"device": "virtio0", "len":
>>> 0, "offset": 0, "speed": 0, "type": "commit"}}
>>> === Performing Live Snapshot 2 ===
>>>
>> Patches 1-3: OK.
>> Patch 4 still breaks test 026...
>>
>> I will try to get this merged, but please run the entire test suite on
>> patch 4 before re-sending.
>>
>> --js
> ah.... Scheisse. The problem is that 026 has 2 results, one for cached,
> one for uncached IO. I have missed that. Give me 5 minutes.
>
> We have fixed uncached mode only.
>
> The problem is clear here.
>
> Den
Tch! I didn't notice myself. Thanks for the catch.
