* [Qemu-devel] [PATCH] block: fix external snapshot abort permission error
@ 2017-06-07 13:55 Jeff Cody
2017-06-07 15:37 ` Eric Blake
2017-06-07 16:52 ` Kevin Wolf
0 siblings, 2 replies; 3+ messages in thread
From: Jeff Cody @ 2017-06-07 13:55 UTC (permalink / raw)
To: qemu-devel; +Cc: qemu-block, kwolf
In external_snapshot_abort(), we try to undo what was done in
external_snapshot_prepare() calling bdrv_replace_node() to swap the
nodes back. However, we receive a permissions error as writers are
blocked on the old node, which is now the new node backing file.
An easy fix (initially suggested by Kevin Wolf) is to call
bdrv_set_backing_hd() on the new node, to set the backing node to NULL.
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
blockdev.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/blockdev.c b/blockdev.c
index 892d768..6472548 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1803,7 +1803,11 @@ static void external_snapshot_abort(BlkActionState *common)
DO_UPCAST(ExternalSnapshotState, common, common);
if (state->new_bs) {
if (state->overlay_appended) {
+ bdrv_ref(state->old_bs); /* we can't let bdrv_set_backind_hd()
+ close state->old_bs; we need it */
+ bdrv_set_backing_hd(state->new_bs, NULL, &error_abort);
bdrv_replace_node(state->new_bs, state->old_bs, &error_abort);
+ bdrv_unref(state->old_bs); /* bdrv_replace_node() ref'ed old_bs */
}
}
}
--
2.9.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block: fix external snapshot abort permission error
2017-06-07 13:55 [Qemu-devel] [PATCH] block: fix external snapshot abort permission error Jeff Cody
@ 2017-06-07 15:37 ` Eric Blake
2017-06-07 16:52 ` Kevin Wolf
1 sibling, 0 replies; 3+ messages in thread
From: Eric Blake @ 2017-06-07 15:37 UTC (permalink / raw)
To: Jeff Cody, qemu-devel; +Cc: kwolf, qemu-block
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On 06/07/2017 08:55 AM, Jeff Cody wrote:
> In external_snapshot_abort(), we try to undo what was done in
> external_snapshot_prepare() calling bdrv_replace_node() to swap the
> nodes back. However, we receive a permissions error as writers are
> blocked on the old node, which is now the new node backing file.
>
> An easy fix (initially suggested by Kevin Wolf) is to call
> bdrv_set_backing_hd() on the new node, to set the backing node to NULL.
>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
> blockdev.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
Reviewed-by: Eric Blake <eblake@redhat.com>
> diff --git a/blockdev.c b/blockdev.c
> index 892d768..6472548 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1803,7 +1803,11 @@ static void external_snapshot_abort(BlkActionState *common)
> DO_UPCAST(ExternalSnapshotState, common, common);
> if (state->new_bs) {
> if (state->overlay_appended) {
> + bdrv_ref(state->old_bs); /* we can't let bdrv_set_backind_hd()
> + close state->old_bs; we need it */
> + bdrv_set_backing_hd(state->new_bs, NULL, &error_abort);
> bdrv_replace_node(state->new_bs, state->old_bs, &error_abort);
> + bdrv_unref(state->old_bs); /* bdrv_replace_node() ref'ed old_bs */
> }
> }
> }
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] block: fix external snapshot abort permission error
2017-06-07 13:55 [Qemu-devel] [PATCH] block: fix external snapshot abort permission error Jeff Cody
2017-06-07 15:37 ` Eric Blake
@ 2017-06-07 16:52 ` Kevin Wolf
1 sibling, 0 replies; 3+ messages in thread
From: Kevin Wolf @ 2017-06-07 16:52 UTC (permalink / raw)
To: Jeff Cody; +Cc: qemu-devel, qemu-block
Am 07.06.2017 um 15:55 hat Jeff Cody geschrieben:
> In external_snapshot_abort(), we try to undo what was done in
> external_snapshot_prepare() calling bdrv_replace_node() to swap the
> nodes back. However, we receive a permissions error as writers are
> blocked on the old node, which is now the new node backing file.
>
> An easy fix (initially suggested by Kevin Wolf) is to call
> bdrv_set_backing_hd() on the new node, to set the backing node to NULL.
>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
Thanks, applied to the block branch.
Kevin
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-06-07 16:52 UTC | newest]
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2017-06-07 13:55 [Qemu-devel] [PATCH] block: fix external snapshot abort permission error Jeff Cody
2017-06-07 15:37 ` Eric Blake
2017-06-07 16:52 ` Kevin Wolf
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