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nbd: backport nbd fix from qemu upstream

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-nbd: Fix regression with multiple meta contexts

Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
This commit is contained in:
Leo Fang 2020-04-15 14:53:39 +08:00
parent df3f209a2a
commit 5b079d4c97
2 changed files with 64 additions and 0 deletions
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60
nbd-Fix-regression-with-multiple-meta-contexts.patch Normal file
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@ -0,0 +1,60 @@
From 32c6cb39cbadd6fc2026ff6311fcf58549f71d49 Mon Sep 17 00:00:00 2001
From: Pan Nengyuan <pannengyuan@huawei.com>
Date: Wed, 15 Apr 2020 14:29:04 +0800
Subject: [PATCH] nbd: Fix regression with multiple meta contexts
Detected by a hang in the libnbd testsuite. If a client requests
multiple meta contexts (both base:allocation and qemu:dirty-bitmap:x)
at the same time, our attempt to silence a false-positive warning
about a potential uninitialized variable introduced botched logic: we
were short-circuiting the second context, and never sending the
NBD_REPLY_FLAG_DONE. Combining two 'if' into one 'if/else' in
bdf200a55 was wrong (I'm a bit embarrassed that such a change was my
initial suggestion after the v1 patch, then I did not review the v2
patch that actually got committed). Revert that, and instead silence
the false positive warning by replacing 'return ret' with 'return 0'
(the value it always has at that point in the code, even though it
eluded the deduction abilities of the robot that reported the false
positive).
Fixes: bdf200a5535
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200206173832.130004-1-eblake@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
(cherry picked from commit 73e064ccf09d908febc83761addcc6e76feabf78)
---
nbd/server.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index aefb07d..3630352 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2304,15 +2304,22 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
!client->export_meta.bitmap,
NBD_META_ID_BASE_ALLOCATION,
errp);
- } else { /* client->export_meta.bitmap */
+ if (ret < 0) {
+ return ret;
+ }
+ }
+ if (client->export_meta.bitmap) {
ret = nbd_co_send_bitmap(client, request->handle,
client->exp->export_bitmap,
request->from, request->len,
dont_fragment,
true, NBD_META_ID_DIRTY_BITMAP, errp);
+ if (ret < 0) {
+ return ret;
+ }
}
- return ret;
+ return 0;
} else {
return nbd_send_generic_reply(client, request->handle, -EINVAL,
"CMD_BLOCK_STATUS not negotiated",
--
1.8.3.1

4
qemu.spec
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@ -63,6 +63,7 @@ Patch0050: pcie-Add-pcie-root-port-fast-plug-unplug-feature.patch
Patch0051: pcie-Compat-with-devices-which-do-not-support-Link-W.patch
Patch0052: aio-wait-delegate-polling-of-main-AioContext-if-BQL-not-held.patch
Patch0053: async-use-explicit-memory-barriers.patch
Patch0054: nbd-Fix-regression-with-multiple-meta-contexts.patch
BuildRequires: flex
BuildRequires: bison
@ -398,6 +399,9 @@ getent passwd qemu >/dev/null || \
%endif
%changelog
* Thu Apr 9 2020 backport nbd fix from qemu upstream
- nbd: Fix regression with multiple meta contexts
* Sat Apr 11 4 2020 Huawei Technologies Co., Ltd. <fangying1@huawei.com>
- aio-wait: delegate polling of main AioContext if BQL not held
- async: use explicit memory barriers