From 7b7974468656d2ceba6a7f6dba2b35dfe28a5d1f Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Mon, 8 Feb 2021 22:57:01 -0300 Subject: [PATCH 03/54] nbd: make nbd_read* return -EIO on error RH-Author: Eric Blake Message-id: <20210208225701.110110-4-eblake@redhat.com> Patchwork-id: 101007 O-Subject: [RHEL-AV-8.4.0 qemu-kvm PATCH v4 3/3] nbd: make nbd_read* return -EIO on error Bugzilla: 1887883 RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Sergio Lopez Pascual RH-Acked-by: Max Reitz From: Roman Kagan NBD reconnect logic considers the error code from the functions that read NBD messages to tell if reconnect should be attempted or not: it is attempted on -EIO, otherwise the client transitions to NBD_CLIENT_QUIT state (see nbd_channel_error). This error code is propagated from the primitives like nbd_read. The problem, however, is that nbd_read itself turns every error into -1 rather than -EIO. As a result, if the NBD server happens to die while sending the message, the client in QEMU receives less data than it expects, considers it as a fatal error, and wouldn't attempt reestablishing the connection. Fix it by turning every negative return from qio_channel_read_all into -EIO returned from nbd_read. Apparently that was the original behavior, but got broken later. Also adjust nbd_readXX to follow. Fixes: e6798f06a6 ("nbd: generalize usage of nbd_read") Signed-off-by: Roman Kagan Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <20210129073859.683063-4-rvkagan@yandex-team.ru> Signed-off-by: Eric Blake (cherry picked from commit 5082fc82a6bc3fc06a04be47d39777c7cff61e5b) Signed-off-by: Eric Blake Signed-off-by: Eduardo Lima (Etrunko) --- include/block/nbd.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/include/block/nbd.h b/include/block/nbd.h index 4a52a43ef5..5f34d23bb0 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -364,7 +364,7 @@ static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size, if (desc) { error_prepend(errp, "Failed to read %s: ", desc); } - return -1; + return ret; } return 0; @@ -375,8 +375,9 @@ static inline int nbd_read##bits(QIOChannel *ioc, \ uint##bits##_t *val, \ const char *desc, Error **errp) \ { \ - if (nbd_read(ioc, val, sizeof(*val), desc, errp) < 0) { \ - return -1; \ + int ret = nbd_read(ioc, val, sizeof(*val), desc, errp); \ + if (ret < 0) { \ + return ret; \ } \ *val = be##bits##_to_cpu(*val); \ return 0; \ -- 2.27.0