block: ignore flush requests when storage is clean

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: N Evgeny Yakovlev <eyakovlev@virtuozzo.com> Signed-off-by: N Denis V. Lunev <den@openvz.org> Reviewed-by: N Paolo Bonzini <pbonzini@redhat.com> Message-id: 1468870792-7411-5-git-send-email-den@openvz.org CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> CC: Fam Zheng <famz@redhat.com> CC: John Snow <jsnow@redhat.com> Signed-off-by: N John Snow <jsnow@redhat.com>

block: ignore flush requests when storage is clean
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: N Evgeny Yakovlev <eyakovlev@virtuozzo.com> Signed-off-by: N Denis V. Lunev <den@openvz.org> Reviewed-by: N Paolo Bonzini <pbonzini@redhat.com> Message-id: 1468870792-7411-5-git-send-email-den@openvz.org CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> CC: Fam Zheng <famz@redhat.com> CC: John Snow <jsnow@redhat.com> Signed-off-by: N John Snow <jsnow@redhat.com>
3ff2f67a · Evgeny Yakovlev · John Snow · 2dd7e10d · 3ff2f67a · 3ff2f67a
9 changed file
--- 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;
 }

--- 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) {
@@ -2236,6 +2237,15 @@ 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);
@@ -2256,6 +2266,11 @@ 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);
@@ -2286,6 +2301,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
         */
        ret = 0;
    }
+
    if (ret < 0) {
        goto out;
    }
@@ -2296,6 +2312,10 @@ 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;
 }
@@ -2421,6 +2441,7 @@ 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);

--- 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;


--- a/tests/qemu-iotests/026.out
+++ b/tests/qemu-iotests/026.out
@@ -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
@@ -306,14 +286,12 @@ 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.
@@ -330,14 +308,12 @@ 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.
@@ -354,14 +330,12 @@ 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.
@@ -378,14 +352,12 @@ 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.
@@ -402,14 +374,12 @@ 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.
@@ -426,14 +396,12 @@ 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.
@@ -450,15 +418,11 @@ 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
@@ -474,15 +438,11 @@ 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.

@@ -553,7 +513,6 @@ 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

@@ -562,7 +521,6 @@ 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

@@ -581,7 +539,6 @@ 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

@@ -590,7 +547,6 @@ 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

@@ -635,8 +591,6 @@ 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
@@ -647,8 +601,6 @@ 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
@@ -659,7 +611,6 @@ 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.
@@ -671,7 +622,6 @@ 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.

--- 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.

--- 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
--- 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 ===

--- 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"}}
@@ -27,9 +27,9 @@ 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"}}

--- 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 ===