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From b55e2f4749d2e4ebfc7dfc8782de85391c1026e8 Mon Sep 17 00:00:00 2001
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From: Fam Zheng <famz@redhat.com>
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Date: Fri, 17 Jan 2014 03:08:00 +0100
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Subject: [PATCH 17/34] commit: Support commit active layer
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RH-Author: Fam Zheng <famz@redhat.com>
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Message-id: <1389928083-8921-16-git-send-email-famz@redhat.com>
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Patchwork-id: 56777
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O-Subject: [RHEL-7 qemu-kvm PATCH 15/18] commit: Support commit active layer
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Bugzilla: 1041301
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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If active is top, it will be mirrored to base, (with block/mirror.c
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code), then the image is switched when user completes the block job.
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QMP documentation is updated.
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 20a63d2cec838c2dde4d246c4d7abe747d9b7a11)
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Signed-off-by: Fam Zheng <famz@redhat.com>
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---
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 block/mirror.c   | 11 +++++++++++
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 blockdev.c       |  9 +++++++--
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 qapi-schema.json |  5 +++--
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 3 files changed, 21 insertions(+), 4 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/mirror.c   |   11 +++++++++++
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 blockdev.c       |    9 +++++++--
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 qapi-schema.json |    5 +++--
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 3 files changed, 21 insertions(+), 4 deletions(-)
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diff --git a/block/mirror.c b/block/mirror.c
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index 01fe379..6e1f9b1 100644
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--- a/block/mirror.c
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+++ b/block/mirror.c
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@@ -478,6 +478,13 @@ immediate_exit:
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             bdrv_reopen(s->target, bdrv_get_flags(s->common.bs), NULL);
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         }
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         bdrv_swap(s->target, s->common.bs);
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+        if (s->common.driver->job_type == BLOCK_JOB_TYPE_COMMIT) {
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+            /* drop the bs loop chain formed by the swap: break the loop then
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+             * trigger the unref from the top one */
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+            BlockDriverState *p = s->base->backing_hd;
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+            s->base->backing_hd = NULL;
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+            bdrv_unref(p);
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+        }
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     }
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     bdrv_unref(s->target);
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     block_job_completed(&s->common, ret);
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@@ -620,6 +627,10 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
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                          BlockDriverCompletionFunc *cb,
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                          void *opaque, Error **errp)
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 {
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+    if (bdrv_reopen(base, bs->open_flags, errp)) {
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+        return;
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+    }
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+    bdrv_ref(base);
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     mirror_start_job(bs, base, speed, 0, 0,
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                      on_error, on_error, cb, opaque, errp,
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                      &commit_active_job_driver, false, base);
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diff --git a/blockdev.c b/blockdev.c
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index d795af2..33a5f5f 100644
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--- a/blockdev.c
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+++ b/blockdev.c
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@@ -1510,8 +1510,13 @@ void qmp_block_commit(const char *device,
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         return;
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     }
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-    commit_start(bs, base_bs, top_bs, speed, on_error, block_job_cb, bs,
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-                &local_err);
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+    if (top_bs == bs) {
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+        commit_active_start(bs, base_bs, speed, on_error, block_job_cb,
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+                            bs, &local_err);
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+    } else {
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+        commit_start(bs, base_bs, top_bs, speed, on_error, block_job_cb, bs,
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+                    &local_err);
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+    }
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     if (local_err != NULL) {
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         error_propagate(errp, local_err);
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         return;
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diff --git a/qapi-schema.json b/qapi-schema.json
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index b0bd53c..a783e8e 100644
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--- a/qapi-schema.json
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+++ b/qapi-schema.json
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@@ -1837,9 +1837,11 @@
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 #
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 # @top:              The file name of the backing image within the image chain,
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 #                    which contains the topmost data to be committed down.
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-#                    Note, the active layer as 'top' is currently unsupported.
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 #
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 #                    If top == base, that is an error.
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+#                    If top == active, the job will not be completed by itself,
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+#                    user needs to complete the job with the block-job-complete
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+#                    command after getting the ready event. (Since 2.0)
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 #
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 #
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 # @speed:  #optional the maximum speed, in bytes per second
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@@ -1849,7 +1851,6 @@
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 #          If @device does not exist, DeviceNotFound
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 #          If image commit is not supported by this device, NotSupported
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 #          If @base or @top is invalid, a generic error is returned
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-#          If @top is the active layer, or omitted, a generic error is returned
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 #          If @speed is invalid, InvalidParameter
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 #
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 # Since: 1.3
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-- 
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1.7.1
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