| Message ID | 20191101100019.9512-2-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | qcow2: Fix data corruption on XFS | expand |
01.11.2019 13:00, Max Reitz wrote: > This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. > > This commit causes fundamental performance problems on XFS (because > fallocate() stalls the AIO pipeline), and as such it is not clear that > we should unconditionally enable this behavior. > > We expect subclusters to alleviate the performance penalty of small > writes to newly allocated clusters, so when we get them, the originally > intended performance gain may actually no longer be significant. > > If we want to reintroduce something similar to c8bb23cbdbe, it will > require extensive benchmarking on various systems with subclusters > enabled. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Max Reitz <mreitz@redhat.com> It's sad, but OK: Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > --- > qapi/block-core.json | 4 +- > block/qcow2.h | 6 --- > block/qcow2-cluster.c | 2 +- > block/qcow2.c | 86 -------------------------------------- > block/trace-events | 1 - > tests/qemu-iotests/060 | 7 +--- > tests/qemu-iotests/060.out | 5 +-- > 7 files changed, 4 insertions(+), 107 deletions(-) > > diff --git a/qapi/block-core.json b/qapi/block-core.json > index aa97ee2641..f053f15431 100644 > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -3304,8 +3304,6 @@ > # > # @cor_write: a write due to copy-on-read (since 2.11) > # > -# @cluster_alloc_space: an allocation of file space for a cluster (since 4.1) > -# > # @none: triggers once at creation of the blkdebug node (since 4.1) > # > # Since: 2.9 > @@ -3326,7 +3324,7 @@ > 'pwritev_rmw_tail', 'pwritev_rmw_after_tail', 'pwritev', > 'pwritev_zero', 'pwritev_done', 'empty_image_prepare', > 'l1_shrink_write_table', 'l1_shrink_free_l2_clusters', > - 'cor_write', 'cluster_alloc_space', 'none'] } > + 'cor_write', 'none'] } > > ## > # @BlkdebugIOType: > diff --git a/block/qcow2.h b/block/qcow2.h > index 601c2e4c82..8166f6e311 100644 > --- a/block/qcow2.h > +++ b/block/qcow2.h > @@ -418,12 +418,6 @@ typedef struct QCowL2Meta > */ > Qcow2COWRegion cow_end; > > - /* > - * Indicates that COW regions are already handled and do not require > - * any more processing. > - */ > - bool skip_cow; > - > /** > * The I/O vector with the data from the actual guest write request. > * If non-NULL, this is meant to be merged together with the data > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c > index 8982b7b762..fbfea8c817 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -809,7 +809,7 @@ static int perform_cow(BlockDriverState *bs, QCowL2Meta *m) > assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes); > assert(start->offset + start->nb_bytes <= end->offset); > > - if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) { > + if (start->nb_bytes == 0 && end->nb_bytes == 0) { > return 0; > } > > diff --git a/block/qcow2.c b/block/qcow2.c > index 7c18721741..17555cb0a1 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -2274,11 +2274,6 @@ static bool merge_cow(uint64_t offset, unsigned bytes, > continue; > } > > - /* If COW regions are handled already, skip this too */ > - if (m->skip_cow) { > - continue; > - } > - > /* The data (middle) region must be immediately after the > * start region */ > if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) { > @@ -2305,81 +2300,6 @@ static bool merge_cow(uint64_t offset, unsigned bytes, > return false; > } > > -static bool is_unallocated(BlockDriverState *bs, int64_t offset, int64_t bytes) > -{ > - int64_t nr; > - return !bytes || > - (!bdrv_is_allocated_above(bs, NULL, false, offset, bytes, &nr) && > - nr == bytes); > -} > - > -static bool is_zero_cow(BlockDriverState *bs, QCowL2Meta *m) > -{ > - /* > - * This check is designed for optimization shortcut so it must be > - * efficient. > - * Instead of is_zero(), use is_unallocated() as it is faster (but not > - * as accurate and can result in false negatives). > - */ > - return is_unallocated(bs, m->offset + m->cow_start.offset, > - m->cow_start.nb_bytes) && > - is_unallocated(bs, m->offset + m->cow_end.offset, > - m->cow_end.nb_bytes); > -} > - > -static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta) > -{ > - BDRVQcow2State *s = bs->opaque; > - QCowL2Meta *m; > - > - if (!(s->data_file->bs->supported_zero_flags & BDRV_REQ_NO_FALLBACK)) { > - return 0; > - } > - > - if (bs->encrypted) { > - return 0; > - } > - > - for (m = l2meta; m != NULL; m = m->next) { > - int ret; > - > - if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) { > - continue; > - } > - > - if (!is_zero_cow(bs, m)) { > - continue; > - } > - > - /* > - * instead of writing zero COW buffers, > - * efficiently zero out the whole clusters > - */ > - > - ret = qcow2_pre_write_overlap_check(bs, 0, m->alloc_offset, > - m->nb_clusters * s->cluster_size, > - true); > - if (ret < 0) { > - return ret; > - } > - > - BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE); > - ret = bdrv_co_pwrite_zeroes(s->data_file, m->alloc_offset, > - m->nb_clusters * s->cluster_size, > - BDRV_REQ_NO_FALLBACK); > - if (ret < 0) { > - if (ret != -ENOTSUP && ret != -EAGAIN) { > - return ret; > - } > - continue; > - } > - > - trace_qcow2_skip_cow(qemu_coroutine_self(), m->offset, m->nb_clusters); > - m->skip_cow = true; > - } > - return 0; > -} > - > /* > * qcow2_co_pwritev_task > * Called with s->lock unlocked > @@ -2421,12 +2341,6 @@ static coroutine_fn int qcow2_co_pwritev_task(BlockDriverState *bs, > qiov_offset = 0; > } > > - /* Try to efficiently initialize the physical space with zeroes */ > - ret = handle_alloc_space(bs, l2meta); > - if (ret < 0) { > - goto out_unlocked; > - } > - > /* > * If we need to do COW, check if it's possible to merge the > * writing of the guest data together with that of the COW regions. > diff --git a/block/trace-events b/block/trace-events > index 6ba86decca..c615b26d71 100644 > --- a/block/trace-events > +++ b/block/trace-events > @@ -72,7 +72,6 @@ qcow2_writev_done_part(void *co, int cur_bytes) "co %p cur_bytes %d" > qcow2_writev_data(void *co, uint64_t offset) "co %p offset 0x%" PRIx64 > qcow2_pwrite_zeroes_start_req(void *co, int64_t offset, int count) "co %p offset 0x%" PRIx64 " count %d" > qcow2_pwrite_zeroes(void *co, int64_t offset, int count) "co %p offset 0x%" PRIx64 " count %d" > -qcow2_skip_cow(void *co, uint64_t offset, int nb_clusters) "co %p offset 0x%" PRIx64 " nb_clusters %d" > > # qcow2-cluster.c > qcow2_alloc_clusters_offset(void *co, uint64_t offset, int bytes) "co %p offset 0x%" PRIx64 " bytes %d" > diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060 > index b91d8321bb..89e911400c 100755 > --- a/tests/qemu-iotests/060 > +++ b/tests/qemu-iotests/060 > @@ -150,15 +150,10 @@ $QEMU_IO -c "$OPEN_RO" -c "read -P 1 0 512" | _filter_qemu_io > echo > echo "=== Testing overlap while COW is in flight ===" > echo > -BACKING_IMG=$TEST_IMG.base > -TEST_IMG=$BACKING_IMG _make_test_img 1G > - > -$QEMU_IO -c 'write 0k 64k' "$BACKING_IMG" | _filter_qemu_io > - > # compat=0.10 is required in order to make the following discard actually > # unallocate the sector rather than make it a zero sector - we want COW, after > # all. > -IMGOPTS='compat=0.10' _make_test_img -b "$BACKING_IMG" 1G > +IMGOPTS='compat=0.10' _make_test_img 1G > # Write two clusters, the second one enforces creation of an L2 table after > # the first data cluster. > $QEMU_IO -c 'write 0k 64k' -c 'write 512M 64k' "$TEST_IMG" | _filter_qemu_io > diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out > index 0f6b0658a1..e42bf8c5a9 100644 > --- a/tests/qemu-iotests/060.out > +++ b/tests/qemu-iotests/060.out > @@ -97,10 +97,7 @@ read 512/512 bytes at offset 0 > > === Testing overlap while COW is in flight === > > -Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=1073741824 > -wrote 65536/65536 bytes at offset 0 > -64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824 backing_file=TEST_DIR/t.IMGFMT.base > +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824 > wrote 65536/65536 bytes at offset 0 > 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > wrote 65536/65536 bytes at offset 536870912 >
On 11/1/19 11:00 AM, Max Reitz wrote: > This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. > > This commit causes fundamental performance problems on XFS (because > fallocate() stalls the AIO pipeline), and as such it is not clear that > we should unconditionally enable this behavior. > > We expect subclusters to alleviate the performance penalty of small > writes to newly allocated clusters, so when we get them, the originally > intended performance gain may actually no longer be significant. > > If we want to reintroduce something similar to c8bb23cbdbe, it will > require extensive benchmarking on various systems with subclusters > enabled. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > +++ b/qapi/block-core.json > @@ -3304,8 +3304,6 @@ > # > # @cor_write: a write due to copy-on-read (since 2.11) > # > -# @cluster_alloc_space: an allocation of file space for a cluster (since 4.1) > -# > # @none: triggers once at creation of the blkdebug node (since 4.1) Deleting released qapi is not backwards-compatible. However, given that the only known user of this interface is debug testing via iotests, I'm not too concerned that we would be impacting any external users.
On 01.11.19 13:40, Eric Blake wrote: > On 11/1/19 11:00 AM, Max Reitz wrote: >> This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. >> >> This commit causes fundamental performance problems on XFS (because >> fallocate() stalls the AIO pipeline), and as such it is not clear that >> we should unconditionally enable this behavior. >> >> We expect subclusters to alleviate the performance penalty of small >> writes to newly allocated clusters, so when we get them, the originally >> intended performance gain may actually no longer be significant. >> >> If we want to reintroduce something similar to c8bb23cbdbe, it will >> require extensive benchmarking on various systems with subclusters >> enabled. >> >> Cc: qemu-stable@nongnu.org >> Signed-off-by: Max Reitz <mreitz@redhat.com> >> --- > >> +++ b/qapi/block-core.json >> @@ -3304,8 +3304,6 @@ >> # >> # @cor_write: a write due to copy-on-read (since 2.11) >> # >> -# @cluster_alloc_space: an allocation of file space for a cluster >> (since 4.1) >> -# >> # @none: triggers once at creation of the blkdebug node (since 4.1) > > Deleting released qapi is not backwards-compatible. Right. :-/ I’ll just not make changes to the QAPI schema. It doesn’t hurt to leave this in. Max > However, given that > the only known user of this interface is debug testing via iotests, I'm > not too concerned that we would be impacting any external users.
Am 01.11.2019 um 15:01 hat Max Reitz geschrieben: > On 01.11.19 13:40, Eric Blake wrote: > > On 11/1/19 11:00 AM, Max Reitz wrote: > >> This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. > >> > >> This commit causes fundamental performance problems on XFS (because > >> fallocate() stalls the AIO pipeline), and as such it is not clear that > >> we should unconditionally enable this behavior. > >> > >> We expect subclusters to alleviate the performance penalty of small > >> writes to newly allocated clusters, so when we get them, the originally > >> intended performance gain may actually no longer be significant. > >> > >> If we want to reintroduce something similar to c8bb23cbdbe, it will > >> require extensive benchmarking on various systems with subclusters > >> enabled. > >> > >> Cc: qemu-stable@nongnu.org > >> Signed-off-by: Max Reitz <mreitz@redhat.com> > >> --- > > > >> +++ b/qapi/block-core.json > >> @@ -3304,8 +3304,6 @@ > >> # > >> # @cor_write: a write due to copy-on-read (since 2.11) > >> # > >> -# @cluster_alloc_space: an allocation of file space for a cluster > >> (since 4.1) > >> -# > >> # @none: triggers once at creation of the blkdebug node (since 4.1) > > > > Deleting released qapi is not backwards-compatible. > > Right. :-/ > > I’ll just not make changes to the QAPI schema. It doesn’t hurt to leave > this in. Why would it be incompatible to drop an enum value that is only ever used in output and that QEMU doesn't generate? Kevin
On 01.11.19 16:42, Kevin Wolf wrote: > Am 01.11.2019 um 15:01 hat Max Reitz geschrieben: >> On 01.11.19 13:40, Eric Blake wrote: >>> On 11/1/19 11:00 AM, Max Reitz wrote: >>>> This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. >>>> >>>> This commit causes fundamental performance problems on XFS (because >>>> fallocate() stalls the AIO pipeline), and as such it is not clear that >>>> we should unconditionally enable this behavior. >>>> >>>> We expect subclusters to alleviate the performance penalty of small >>>> writes to newly allocated clusters, so when we get them, the originally >>>> intended performance gain may actually no longer be significant. >>>> >>>> If we want to reintroduce something similar to c8bb23cbdbe, it will >>>> require extensive benchmarking on various systems with subclusters >>>> enabled. >>>> >>>> Cc: qemu-stable@nongnu.org >>>> Signed-off-by: Max Reitz <mreitz@redhat.com> >>>> --- >>> >>>> +++ b/qapi/block-core.json >>>> @@ -3304,8 +3304,6 @@ >>>> # >>>> # @cor_write: a write due to copy-on-read (since 2.11) >>>> # >>>> -# @cluster_alloc_space: an allocation of file space for a cluster >>>> (since 4.1) >>>> -# >>>> # @none: triggers once at creation of the blkdebug node (since 4.1) >>> >>> Deleting released qapi is not backwards-compatible. >> >> Right. :-/ >> >> I’ll just not make changes to the QAPI schema. It doesn’t hurt to leave >> this in. > > Why would it be incompatible to drop an enum value that is only ever > used in output and that QEMU doesn't generate? This isn’t output at all, it’s input for blockdev-add for blkdebug nodes. Max
diff --git a/qapi/block-core.json b/qapi/block-core.json index aa97ee2641..f053f15431 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -3304,8 +3304,6 @@ # # @cor_write: a write due to copy-on-read (since 2.11) # -# @cluster_alloc_space: an allocation of file space for a cluster (since 4.1) -# # @none: triggers once at creation of the blkdebug node (since 4.1) # # Since: 2.9 @@ -3326,7 +3324,7 @@ 'pwritev_rmw_tail', 'pwritev_rmw_after_tail', 'pwritev', 'pwritev_zero', 'pwritev_done', 'empty_image_prepare', 'l1_shrink_write_table', 'l1_shrink_free_l2_clusters', - 'cor_write', 'cluster_alloc_space', 'none'] } + 'cor_write', 'none'] } ## # @BlkdebugIOType: diff --git a/block/qcow2.h b/block/qcow2.h index 601c2e4c82..8166f6e311 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -418,12 +418,6 @@ typedef struct QCowL2Meta */ Qcow2COWRegion cow_end; - /* - * Indicates that COW regions are already handled and do not require - * any more processing. - */ - bool skip_cow; - /** * The I/O vector with the data from the actual guest write request. * If non-NULL, this is meant to be merged together with the data diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 8982b7b762..fbfea8c817 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -809,7 +809,7 @@ static int perform_cow(BlockDriverState *bs, QCowL2Meta *m) assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes); assert(start->offset + start->nb_bytes <= end->offset); - if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) { + if (start->nb_bytes == 0 && end->nb_bytes == 0) { return 0; } diff --git a/block/qcow2.c b/block/qcow2.c index 7c18721741..17555cb0a1 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2274,11 +2274,6 @@ static bool merge_cow(uint64_t offset, unsigned bytes, continue; } - /* If COW regions are handled already, skip this too */ - if (m->skip_cow) { - continue; - } - /* The data (middle) region must be immediately after the * start region */ if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) { @@ -2305,81 +2300,6 @@ static bool merge_cow(uint64_t offset, unsigned bytes, return false; } -static bool is_unallocated(BlockDriverState *bs, int64_t offset, int64_t bytes) -{ - int64_t nr; - return !bytes || - (!bdrv_is_allocated_above(bs, NULL, false, offset, bytes, &nr) && - nr == bytes); -} - -static bool is_zero_cow(BlockDriverState *bs, QCowL2Meta *m) -{ - /* - * This check is designed for optimization shortcut so it must be - * efficient. - * Instead of is_zero(), use is_unallocated() as it is faster (but not - * as accurate and can result in false negatives). - */ - return is_unallocated(bs, m->offset + m->cow_start.offset, - m->cow_start.nb_bytes) && - is_unallocated(bs, m->offset + m->cow_end.offset, - m->cow_end.nb_bytes); -} - -static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta) -{ - BDRVQcow2State *s = bs->opaque; - QCowL2Meta *m; - - if (!(s->data_file->bs->supported_zero_flags & BDRV_REQ_NO_FALLBACK)) { - return 0; - } - - if (bs->encrypted) { - return 0; - } - - for (m = l2meta; m != NULL; m = m->next) { - int ret; - - if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) { - continue; - } - - if (!is_zero_cow(bs, m)) { - continue; - } - - /* - * instead of writing zero COW buffers, - * efficiently zero out the whole clusters - */ - - ret = qcow2_pre_write_overlap_check(bs, 0, m->alloc_offset, - m->nb_clusters * s->cluster_size, - true); - if (ret < 0) { - return ret; - } - - BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE); - ret = bdrv_co_pwrite_zeroes(s->data_file, m->alloc_offset, - m->nb_clusters * s->cluster_size, - BDRV_REQ_NO_FALLBACK); - if (ret < 0) { - if (ret != -ENOTSUP && ret != -EAGAIN) { - return ret; - } - continue; - } - - trace_qcow2_skip_cow(qemu_coroutine_self(), m->offset, m->nb_clusters); - m->skip_cow = true; - } - return 0; -} - /* * qcow2_co_pwritev_task * Called with s->lock unlocked @@ -2421,12 +2341,6 @@ static coroutine_fn int qcow2_co_pwritev_task(BlockDriverState *bs, qiov_offset = 0; } - /* Try to efficiently initialize the physical space with zeroes */ - ret = handle_alloc_space(bs, l2meta); - if (ret < 0) { - goto out_unlocked; - } - /* * If we need to do COW, check if it's possible to merge the * writing of the guest data together with that of the COW regions. diff --git a/block/trace-events b/block/trace-events index 6ba86decca..c615b26d71 100644 --- a/block/trace-events +++ b/block/trace-events @@ -72,7 +72,6 @@ qcow2_writev_done_part(void *co, int cur_bytes) "co %p cur_bytes %d" qcow2_writev_data(void *co, uint64_t offset) "co %p offset 0x%" PRIx64 qcow2_pwrite_zeroes_start_req(void *co, int64_t offset, int count) "co %p offset 0x%" PRIx64 " count %d" qcow2_pwrite_zeroes(void *co, int64_t offset, int count) "co %p offset 0x%" PRIx64 " count %d" -qcow2_skip_cow(void *co, uint64_t offset, int nb_clusters) "co %p offset 0x%" PRIx64 " nb_clusters %d" # qcow2-cluster.c qcow2_alloc_clusters_offset(void *co, uint64_t offset, int bytes) "co %p offset 0x%" PRIx64 " bytes %d" diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060 index b91d8321bb..89e911400c 100755 --- a/tests/qemu-iotests/060 +++ b/tests/qemu-iotests/060 @@ -150,15 +150,10 @@ $QEMU_IO -c "$OPEN_RO" -c "read -P 1 0 512" | _filter_qemu_io echo echo "=== Testing overlap while COW is in flight ===" echo -BACKING_IMG=$TEST_IMG.base -TEST_IMG=$BACKING_IMG _make_test_img 1G - -$QEMU_IO -c 'write 0k 64k' "$BACKING_IMG" | _filter_qemu_io - # compat=0.10 is required in order to make the following discard actually # unallocate the sector rather than make it a zero sector - we want COW, after # all. -IMGOPTS='compat=0.10' _make_test_img -b "$BACKING_IMG" 1G +IMGOPTS='compat=0.10' _make_test_img 1G # Write two clusters, the second one enforces creation of an L2 table after # the first data cluster. $QEMU_IO -c 'write 0k 64k' -c 'write 512M 64k' "$TEST_IMG" | _filter_qemu_io diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out index 0f6b0658a1..e42bf8c5a9 100644 --- a/tests/qemu-iotests/060.out +++ b/tests/qemu-iotests/060.out @@ -97,10 +97,7 @@ read 512/512 bytes at offset 0 === Testing overlap while COW is in flight === -Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=1073741824 -wrote 65536/65536 bytes at offset 0 -64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824 backing_file=TEST_DIR/t.IMGFMT.base +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1073741824 wrote 65536/65536 bytes at offset 0 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) wrote 65536/65536 bytes at offset 536870912
This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. This commit causes fundamental performance problems on XFS (because fallocate() stalls the AIO pipeline), and as such it is not clear that we should unconditionally enable this behavior. We expect subclusters to alleviate the performance penalty of small writes to newly allocated clusters, so when we get them, the originally intended performance gain may actually no longer be significant. If we want to reintroduce something similar to c8bb23cbdbe, it will require extensive benchmarking on various systems with subclusters enabled. Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz <mreitz@redhat.com> --- qapi/block-core.json | 4 +- block/qcow2.h | 6 --- block/qcow2-cluster.c | 2 +- block/qcow2.c | 86 -------------------------------------- block/trace-events | 1 - tests/qemu-iotests/060 | 7 +--- tests/qemu-iotests/060.out | 5 +-- 7 files changed, 4 insertions(+), 107 deletions(-)