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From d193d49f5180d6a6b959808368247cdd506bf989 Mon Sep 17 00:00:00 2001
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From: Fam Zheng <famz@redhat.com>
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Date: Fri, 29 Jun 2018 06:11:41 +0200
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Subject: [PATCH 167/268] block: Introduce API for copy offloading
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RH-Author: Fam Zheng <famz@redhat.com>
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Message-id: <20180629061153.12687-2-famz@redhat.com>
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Patchwork-id: 81153
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH v2 01/13] block: Introduce API for copy offloading
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Bugzilla: 1482537
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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Introduce the bdrv_co_copy_range() API for copy offloading.  Block
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drivers implementing this API support efficient copy operations that
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avoid reading each block from the source device and writing it to the
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destination devices.  Examples of copy offload primitives are SCSI
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EXTENDED COPY and Linux copy_file_range(2).
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-id: 20180601092648.24614-2-famz@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit fcc6767836efe1b160289905dce7228d594c123c)
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/io.c                | 97 +++++++++++++++++++++++++++++++++++++++++++++++
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 include/block/block.h     | 32 ++++++++++++++++
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 include/block/block_int.h | 38 +++++++++++++++++++
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 3 files changed, 167 insertions(+)
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diff --git a/block/io.c b/block/io.c
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index fada4ef..5c043a4 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -2832,3 +2832,100 @@ void bdrv_unregister_buf(BlockDriverState *bs, void *host)
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         bdrv_unregister_buf(child->bs, host);
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     }
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 }
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+
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+static int coroutine_fn bdrv_co_copy_range_internal(BdrvChild *src,
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+                                                    uint64_t src_offset,
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+                                                    BdrvChild *dst,
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+                                                    uint64_t dst_offset,
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+                                                    uint64_t bytes,
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+                                                    BdrvRequestFlags flags,
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+                                                    bool recurse_src)
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+{
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+    int ret;
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+
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+    if (!src || !dst || !src->bs || !dst->bs) {
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+        return -ENOMEDIUM;
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+    }
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+    ret = bdrv_check_byte_request(src->bs, src_offset, bytes);
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+    if (ret) {
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+        return ret;
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+    }
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+
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+    ret = bdrv_check_byte_request(dst->bs, dst_offset, bytes);
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+    if (ret) {
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+        return ret;
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+    }
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+    if (flags & BDRV_REQ_ZERO_WRITE) {
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+        return bdrv_co_pwrite_zeroes(dst, dst_offset, bytes, flags);
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+    }
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+
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+    if (!src->bs->drv->bdrv_co_copy_range_from
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+        || !dst->bs->drv->bdrv_co_copy_range_to
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+        || src->bs->encrypted || dst->bs->encrypted) {
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+        return -ENOTSUP;
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+    }
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+    if (recurse_src) {
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+        return src->bs->drv->bdrv_co_copy_range_from(src->bs,
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+                                                     src, src_offset,
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+                                                     dst, dst_offset,
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+                                                     bytes, flags);
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+    } else {
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+        return dst->bs->drv->bdrv_co_copy_range_to(dst->bs,
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+                                                   src, src_offset,
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+                                                   dst, dst_offset,
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+                                                   bytes, flags);
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+    }
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+}
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+
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+/* Copy range from @src to @dst.
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+ *
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+ * See the comment of bdrv_co_copy_range for the parameter and return value
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+ * semantics. */
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+int coroutine_fn bdrv_co_copy_range_from(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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+    return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset,
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+                                       bytes, flags, true);
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+}
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+
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+/* Copy range from @src to @dst.
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+ *
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+ * See the comment of bdrv_co_copy_range for the parameter and return value
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+ * semantics. */
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+int coroutine_fn bdrv_co_copy_range_to(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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+    return bdrv_co_copy_range_internal(src, src_offset, dst, dst_offset,
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+                                       bytes, flags, false);
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+}
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+
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+int coroutine_fn bdrv_co_copy_range(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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+    BdrvTrackedRequest src_req, dst_req;
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+    BlockDriverState *src_bs = src->bs;
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+    BlockDriverState *dst_bs = dst->bs;
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+    int ret;
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+
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+    bdrv_inc_in_flight(src_bs);
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+    bdrv_inc_in_flight(dst_bs);
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+    tracked_request_begin(&src_req, src_bs, src_offset,
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+                          bytes, BDRV_TRACKED_READ);
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+    tracked_request_begin(&dst_req, dst_bs, dst_offset,
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+                          bytes, BDRV_TRACKED_WRITE);
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+
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+    wait_serialising_requests(&src_req);
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+    wait_serialising_requests(&dst_req);
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+    ret = bdrv_co_copy_range_from(src, src_offset,
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+                                  dst, dst_offset,
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+                                  bytes, flags);
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+
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+    tracked_request_end(&src_req);
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+    tracked_request_end(&dst_req);
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+    bdrv_dec_in_flight(src_bs);
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+    bdrv_dec_in_flight(dst_bs);
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+    return ret;
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+}
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diff --git a/include/block/block.h b/include/block/block.h
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index 2d17b09..e677080 100644
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--- a/include/block/block.h
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+++ b/include/block/block.h
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@@ -613,4 +613,36 @@ bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
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  */
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 void bdrv_register_buf(BlockDriverState *bs, void *host, size_t size);
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 void bdrv_unregister_buf(BlockDriverState *bs, void *host);
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+
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+/**
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+ *
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+ * bdrv_co_copy_range:
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+ *
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+ * Do offloaded copy between two children. If the operation is not implemented
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+ * by the driver, or if the backend storage doesn't support it, a negative
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+ * error code will be returned.
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+ *
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+ * Note: block layer doesn't emulate or fallback to a bounce buffer approach
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+ * because usually the caller shouldn't attempt offloaded copy any more (e.g.
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+ * calling copy_file_range(2)) after the first error, thus it should fall back
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+ * to a read+write path in the caller level.
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+ *
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+ * @src: Source child to copy data from
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+ * @src_offset: offset in @src image to read data
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+ * @dst: Destination child to copy data to
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+ * @dst_offset: offset in @dst image to write data
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+ * @bytes: number of bytes to copy
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+ * @flags: request flags. Must be one of:
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+ *         0 - actually read data from src;
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+ *         BDRV_REQ_ZERO_WRITE - treat the @src range as zero data and do zero
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+ *                               write on @dst as if bdrv_co_pwrite_zeroes is
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+ *                               called. Used to simplify caller code, or
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+ *                               during BlockDriver.bdrv_co_copy_range_from()
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+ *                               recursion.
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+ *
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+ * Returns: 0 if succeeded; negative error code if failed.
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+ **/
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+int coroutine_fn bdrv_co_copy_range(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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 #endif
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diff --git a/include/block/block_int.h b/include/block/block_int.h
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index ad2b852..3da86a7 100644
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--- a/include/block/block_int.h
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+++ b/include/block/block_int.h
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@@ -206,6 +206,37 @@ struct BlockDriver {
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     int coroutine_fn (*bdrv_co_pdiscard)(BlockDriverState *bs,
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         int64_t offset, int bytes);
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+    /* Map [offset, offset + nbytes) range onto a child of @bs to copy from,
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+     * and invoke bdrv_co_copy_range_from(child, ...), or invoke
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+     * bdrv_co_copy_range_to() if @bs is the leaf child to copy data from.
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+     *
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+     * See the comment of bdrv_co_copy_range for the parameter and return value
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+     * semantics.
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+     */
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+    int coroutine_fn (*bdrv_co_copy_range_from)(BlockDriverState *bs,
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+                                                BdrvChild *src,
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+                                                uint64_t offset,
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+                                                BdrvChild *dst,
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+                                                uint64_t dst_offset,
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+                                                uint64_t bytes,
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+                                                BdrvRequestFlags flags);
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+
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+    /* Map [offset, offset + nbytes) range onto a child of bs to copy data to,
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+     * and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy
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+     * operation if @bs is the leaf and @src has the same BlockDriver.  Return
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+     * -ENOTSUP if @bs is the leaf but @src has a different BlockDriver.
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+     *
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+     * See the comment of bdrv_co_copy_range for the parameter and return value
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+     * semantics.
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+     */
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+    int coroutine_fn (*bdrv_co_copy_range_to)(BlockDriverState *bs,
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+                                              BdrvChild *src,
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+                                              uint64_t src_offset,
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+                                              BdrvChild *dst,
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+                                              uint64_t dst_offset,
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+                                              uint64_t bytes,
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+                                              BdrvRequestFlags flags);
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+
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     /*
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      * Building block for bdrv_block_status[_above] and
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      * bdrv_is_allocated[_above].  The driver should answer only
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@@ -1091,4 +1122,11 @@ void bdrv_dec_in_flight(BlockDriverState *bs);
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 void blockdev_close_all_bdrv_states(void);
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+int coroutine_fn bdrv_co_copy_range_from(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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+int coroutine_fn bdrv_co_copy_range_to(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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 #endif /* BLOCK_INT_H */
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-- 
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1.8.3.1
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