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From 088ddadf21938cfa527bb47ce5452ad502ff2c8d Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Wed, 18 Jul 2018 22:54:51 +0200
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Subject: [PATCH 233/268] block: Honour BDRV_REQ_NO_SERIALISING in copy range
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RH-Author: John Snow <jsnow@redhat.com>
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Message-id: <20180718225511.14878-16-jsnow@redhat.com>
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Patchwork-id: 81402
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O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 15/35] block: Honour BDRV_REQ_NO_SERIALISING in copy range
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Bugzilla: 1207657
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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From: Fam Zheng <famz@redhat.com>
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This semantics is needed by drive-backup so implement it before using
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this API there.
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Message-id: 20180703023758.14422-3-famz@redhat.com
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Signed-off-by: Jeff Cody <jcody@redhat.com>
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(cherry picked from commit dee12de89380483656072f775f5ef99f4426f966)
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Signed-off-by: John Snow <jsnow@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            | 6 ++++--
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 include/block/block.h | 5 +++--
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 2 files changed, 7 insertions(+), 4 deletions(-)
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diff --git a/block/io.c b/block/io.c
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index 7981239..b6754f3 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -2883,8 +2883,10 @@ static int coroutine_fn bdrv_co_copy_range_internal(BdrvChild *src,
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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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-    wait_serialising_requests(&src_req);
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-    wait_serialising_requests(&dst_req);
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+    if (!(flags & BDRV_REQ_NO_SERIALISING)) {
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+        wait_serialising_requests(&src_req);
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+        wait_serialising_requests(&dst_req);
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+    }
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     if (recurse_src) {
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         ret = src->bs->drv->bdrv_co_copy_range_from(src->bs,
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                                                     src, src_offset,
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diff --git a/include/block/block.h b/include/block/block.h
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index c3cfb40..e1d5e47 100644
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--- a/include/block/block.h
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+++ b/include/block/block.h
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@@ -636,13 +636,14 @@ void bdrv_unregister_buf(BlockDriverState *bs, void *host);
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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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+ * @flags: request flags. Supported flags:
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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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+ *         BDRV_REQ_NO_SERIALISING - do not serialize with other overlapping
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+ *                                   requests currently in flight.
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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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-- 
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1.8.3.1
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