From: Eric Blake <eblake@redhat.com>
To: qemu-devel@nongnu.org
Cc: Roman Kagan <rvkagan@yandex-team.ru>,
Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
"open list:Network Block Dev..." <qemu-block@nongnu.org>,
Max Reitz <mreitz@redhat.com>
Subject: [PULL 20/20] nbd: make nbd_read* return -EIO on error
Date: Tue, 2 Feb 2021 16:45:29 -0600 [thread overview]
Message-ID: <20210202224529.642055-21-eblake@redhat.com> (raw)
In-Reply-To: <20210202224529.642055-1-eblake@redhat.com>
From: Roman Kagan <rvkagan@yandex-team.ru>
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 <rvkagan@yandex-team.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210129073859.683063-4-rvkagan@yandex-team.ru>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
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 4a52a43ef598..5f34d23bb037 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; \
--
2.30.0
next prev parent reply other threads:[~2021-02-02 23:09 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 22:45 [PULL 00/20] NBD patches for 2021-02-02 Eric Blake
2021-02-02 22:45 ` [PULL 01/20] iotests: Fix expected whitespace for 185 Eric Blake
2021-02-02 22:45 ` [PULL 02/20] block: refactor bdrv_check_request: add errp Eric Blake
2021-02-02 22:45 ` [PULL 03/20] util/iov: make qemu_iovec_init_extended() honest Eric Blake
2021-02-02 22:45 ` [PULL 04/20] block: fix theoretical overflow in bdrv_init_padding() Eric Blake
2021-02-02 22:45 ` [PULL 05/20] block/io: refactor bdrv_pad_request(): move bdrv_pad_request() up Eric Blake
2021-02-02 22:45 ` [PULL 06/20] block/io: bdrv_pad_request(): support qemu_iovec_init_extended failure Eric Blake
2021-02-02 22:45 ` [PULL 07/20] block/throttle-groups: throttle_group_co_io_limits_intercept(): 64bit bytes Eric Blake
2021-02-02 22:45 ` [PULL 08/20] block/io: improve bdrv_check_request: check qiov too Eric Blake
2021-02-02 22:45 ` [PULL 09/20] block: use int64_t as bytes type in tracked requests Eric Blake
2021-02-02 22:45 ` [PULL 10/20] block/io: use int64_t bytes in driver wrappers Eric Blake
2021-02-02 22:45 ` [PULL 11/20] block/io: support int64_t bytes in bdrv_co_do_pwrite_zeroes() Eric Blake
2021-02-02 22:45 ` [PULL 12/20] block/io: support int64_t bytes in bdrv_aligned_pwritev() Eric Blake
2021-02-02 22:45 ` [PULL 13/20] block/io: support int64_t bytes in bdrv_co_do_copy_on_readv() Eric Blake
2021-02-02 22:45 ` [PULL 14/20] block/io: support int64_t bytes in bdrv_aligned_preadv() Eric Blake
2021-02-02 22:45 ` [PULL 15/20] block/io: support int64_t bytes in bdrv_co_p{read, write}v_part() Eric Blake
2021-02-02 22:45 ` [PULL 16/20] block/io: support int64_t bytes in read/write wrappers Eric Blake
2021-02-02 22:45 ` [PULL 17/20] block/io: use int64_t bytes in copy_range Eric Blake
2021-02-02 22:45 ` [PULL 18/20] block/nbd: only detach existing iochannel from aio_context Eric Blake
2021-02-02 22:45 ` [PULL 19/20] block/nbd: only enter connection coroutine if it's present Eric Blake
2021-02-02 22:45 ` Eric Blake [this message]
2021-02-02 23:12 ` [PULL 00/20] NBD patches for 2021-02-02 no-reply
2021-02-03 13:25 ` Eric Blake
2021-02-03 13:27 ` Eric Blake
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