qcow2: Implement copy offloading
The two callbacks are implemented quite similarly to the read/write functions: bdrv_co_copy_range_from maps for read and calls into bs->file or bs->backing depending on the allocation status; bdrv_co_copy_range_to maps for write and calls into bs->file. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Fam Zheng <famz@redhat.com> Message-id: 20180601092648.24614-5-famz@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng
Stefan Hajnoczi
parent
72d219e2f9
commit
fd9fcd37a8
229
block/qcow2.c
229
block/qcow2.c
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@ -1761,6 +1761,39 @@ static int coroutine_fn qcow2_co_block_status(BlockDriverState *bs,
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return status;
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}
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static coroutine_fn int qcow2_handle_l2meta(BlockDriverState *bs,
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QCowL2Meta **pl2meta,
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bool link_l2)
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{
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int ret = 0;
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QCowL2Meta *l2meta = *pl2meta;
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while (l2meta != NULL) {
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QCowL2Meta *next;
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if (!ret && link_l2) {
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ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
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if (ret) {
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goto out;
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}
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}
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/* Take the request off the list of running requests */
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if (l2meta->nb_clusters != 0) {
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QLIST_REMOVE(l2meta, next_in_flight);
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}
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qemu_co_queue_restart_all(&l2meta->dependent_requests);
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next = l2meta->next;
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g_free(l2meta);
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l2meta = next;
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}
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out:
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*pl2meta = l2meta;
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return ret;
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}
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static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
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uint64_t bytes, QEMUIOVector *qiov,
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int flags)
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@ -2047,24 +2080,9 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
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}
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}
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while (l2meta != NULL) {
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QCowL2Meta *next;
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ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
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if (ret < 0) {
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goto fail;
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}
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/* Take the request off the list of running requests */
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if (l2meta->nb_clusters != 0) {
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QLIST_REMOVE(l2meta, next_in_flight);
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}
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qemu_co_queue_restart_all(&l2meta->dependent_requests);
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next = l2meta->next;
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g_free(l2meta);
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l2meta = next;
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ret = qcow2_handle_l2meta(bs, &l2meta, true);
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if (ret) {
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goto fail;
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}
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bytes -= cur_bytes;
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@ -2075,18 +2093,7 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState *bs, uint64_t offset,
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ret = 0;
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fail:
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while (l2meta != NULL) {
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QCowL2Meta *next;
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if (l2meta->nb_clusters != 0) {
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QLIST_REMOVE(l2meta, next_in_flight);
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}
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qemu_co_queue_restart_all(&l2meta->dependent_requests);
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next = l2meta->next;
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g_free(l2meta);
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l2meta = next;
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}
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qcow2_handle_l2meta(bs, &l2meta, false);
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qemu_co_mutex_unlock(&s->lock);
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@ -3273,6 +3280,166 @@ static coroutine_fn int qcow2_co_pdiscard(BlockDriverState *bs,
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return ret;
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}
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static int coroutine_fn
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qcow2_co_copy_range_from(BlockDriverState *bs,
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BdrvChild *src, uint64_t src_offset,
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BdrvChild *dst, uint64_t dst_offset,
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uint64_t bytes, BdrvRequestFlags flags)
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{
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BDRVQcow2State *s = bs->opaque;
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int ret;
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unsigned int cur_bytes; /* number of bytes in current iteration */
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BdrvChild *child = NULL;
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BdrvRequestFlags cur_flags;
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assert(!bs->encrypted);
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qemu_co_mutex_lock(&s->lock);
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while (bytes != 0) {
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uint64_t copy_offset = 0;
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/* prepare next request */
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cur_bytes = MIN(bytes, INT_MAX);
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cur_flags = flags;
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ret = qcow2_get_cluster_offset(bs, src_offset, &cur_bytes, ©_offset);
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if (ret < 0) {
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goto out;
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}
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switch (ret) {
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case QCOW2_CLUSTER_UNALLOCATED:
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if (bs->backing && bs->backing->bs) {
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int64_t backing_length = bdrv_getlength(bs->backing->bs);
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if (src_offset >= backing_length) {
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cur_flags |= BDRV_REQ_ZERO_WRITE;
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} else {
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child = bs->backing;
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cur_bytes = MIN(cur_bytes, backing_length - src_offset);
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copy_offset = src_offset;
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}
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} else {
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cur_flags |= BDRV_REQ_ZERO_WRITE;
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}
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break;
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case QCOW2_CLUSTER_ZERO_PLAIN:
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case QCOW2_CLUSTER_ZERO_ALLOC:
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cur_flags |= BDRV_REQ_ZERO_WRITE;
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break;
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case QCOW2_CLUSTER_COMPRESSED:
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ret = -ENOTSUP;
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goto out;
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break;
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case QCOW2_CLUSTER_NORMAL:
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child = bs->file;
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copy_offset += offset_into_cluster(s, src_offset);
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if ((copy_offset & 511) != 0) {
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ret = -EIO;
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goto out;
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}
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break;
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default:
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abort();
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}
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qemu_co_mutex_unlock(&s->lock);
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ret = bdrv_co_copy_range_from(child,
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copy_offset,
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dst, dst_offset,
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cur_bytes, cur_flags);
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qemu_co_mutex_lock(&s->lock);
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if (ret < 0) {
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goto out;
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}
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bytes -= cur_bytes;
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src_offset += cur_bytes;
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dst_offset += cur_bytes;
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}
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ret = 0;
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out:
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qemu_co_mutex_unlock(&s->lock);
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return ret;
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}
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static int coroutine_fn
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qcow2_co_copy_range_to(BlockDriverState *bs,
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BdrvChild *src, uint64_t src_offset,
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BdrvChild *dst, uint64_t dst_offset,
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uint64_t bytes, BdrvRequestFlags flags)
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{
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BDRVQcow2State *s = bs->opaque;
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int offset_in_cluster;
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int ret;
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unsigned int cur_bytes; /* number of sectors in current iteration */
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uint64_t cluster_offset;
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uint8_t *cluster_data = NULL;
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QCowL2Meta *l2meta = NULL;
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assert(!bs->encrypted);
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s->cluster_cache_offset = -1; /* disable compressed cache */
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qemu_co_mutex_lock(&s->lock);
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while (bytes != 0) {
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l2meta = NULL;
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offset_in_cluster = offset_into_cluster(s, dst_offset);
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cur_bytes = MIN(bytes, INT_MAX);
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/* TODO:
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* If src->bs == dst->bs, we could simply copy by incrementing
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* the refcnt, without copying user data.
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* Or if src->bs == dst->bs->backing->bs, we could copy by discarding. */
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ret = qcow2_alloc_cluster_offset(bs, dst_offset, &cur_bytes,
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&cluster_offset, &l2meta);
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if (ret < 0) {
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goto fail;
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}
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assert((cluster_offset & 511) == 0);
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ret = qcow2_pre_write_overlap_check(bs, 0,
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cluster_offset + offset_in_cluster, cur_bytes);
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if (ret < 0) {
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goto fail;
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}
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qemu_co_mutex_unlock(&s->lock);
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ret = bdrv_co_copy_range_to(src, src_offset,
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bs->file,
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cluster_offset + offset_in_cluster,
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cur_bytes, flags);
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qemu_co_mutex_lock(&s->lock);
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if (ret < 0) {
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goto fail;
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}
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ret = qcow2_handle_l2meta(bs, &l2meta, true);
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if (ret) {
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goto fail;
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}
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bytes -= cur_bytes;
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dst_offset += cur_bytes;
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}
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ret = 0;
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fail:
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qcow2_handle_l2meta(bs, &l2meta, false);
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qemu_co_mutex_unlock(&s->lock);
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qemu_vfree(cluster_data);
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trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
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return ret;
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}
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static int qcow2_truncate(BlockDriverState *bs, int64_t offset,
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PreallocMode prealloc, Error **errp)
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{
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@ -4521,6 +4688,8 @@ BlockDriver bdrv_qcow2 = {
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.bdrv_co_pwrite_zeroes = qcow2_co_pwrite_zeroes,
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.bdrv_co_pdiscard = qcow2_co_pdiscard,
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.bdrv_co_copy_range_from = qcow2_co_copy_range_from,
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.bdrv_co_copy_range_to = qcow2_co_copy_range_to,
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.bdrv_truncate = qcow2_truncate,
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.bdrv_co_pwritev_compressed = qcow2_co_pwritev_compressed,
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.bdrv_make_empty = qcow2_make_empty,
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