From 32c6cb39cbadd6fc2026ff6311fcf58549f71d49 Mon Sep 17 00:00:00 2001 From: Pan Nengyuan 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 Message-Id: <20200206173832.130004-1-eblake@redhat.com> Reviewed-by: Laurent Vivier (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