+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Eric Blake <eblake@redhat.com>
+Date: Wed, 19 Jul 2017 18:02:00 +0200
+Subject: [PATCH] nbd: read_sync and friends: return 0 on success
+
+RH-Author: Eric Blake <eblake@redhat.com>
+Message-id: <20170719180202.23329-3-eblake@redhat.com>
+Patchwork-id: 75818
+O-Subject: [RHEV-7.4.z qemu-kvm-rhev PATCH 2/4] nbd: read_sync and friends: return 0 on success
+Bugzilla: 1467509
+RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
+RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
+RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
+
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+
+functions read_sync, drop_sync, write_sync, and also
+nbd_negotiate_write, nbd_negotiate_read, nbd_negotiate_drop_sync
+returns number of processed bytes. But what this number can be,
+except requested number of bytes?
+
+Actually, underlying nbd_wr_syncv function returns a value >= 0 and
+!= requested_bytes only on eof on read operation. So, firstly, it is
+impossible on write (let's add an assert) and on read it actually
+means, that communication is broken (except nbd_receive_reply, see
+below).
+
+Most of callers operate like this:
+ if (func(..., size) != size) {
+ /* error path */
+ }
+, i.e.:
+ 1. They are not interested in partial success
+ 2. Extra duplications in code (especially bad are duplications of
+ magic numbers)
+ 3. User doesn't see actual error message, as return code is lost.
+ (this patch doesn't fix this point, but it makes fixing easier)
+
+Several callers handles ret >= 0 and != requested-size separately, by
+just returning EINVAL in this case. This patch makes read_sync and
+friends return EINVAL in this case, so final behavior is the same.
+
+And only one caller - nbd_receive_reply() does something not so
+obvious. It returns EINVAL for ret > 0 and != requested-size, like
+previous group, but for ret == 0 it returns 0. The only caller of
+nbd_receive_reply() - nbd_read_reply_entry() handles ret == 0 in the
+same way as ret < 0, so for now it doesn't matter. However, in
+following commits error path handling will be improved and we'll need
+to distinguish success from fail in this case too. So, this patch adds
+separate helper for this case - read_sync_eof.
+
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Message-Id: <20170516094533.6160-3-vsementsov@virtuozzo.com>
+Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
+(cherry picked from commit f5d406fe86bb28da85824b6581e58980cc1a07f3)
+Signed-off-by: Eric Blake <eblake@redhat.com>
+Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
+---
+ nbd/client.c | 63 ++++++++++++++++------------------------
+ nbd/nbd-internal.h | 34 +++++++++++++++++++---
+ nbd/server.c | 84 +++++++++++++++++++++---------------------------------
+ 3 files changed, 88 insertions(+), 93 deletions(-)
+
+diff --git a/nbd/client.c b/nbd/client.c
+index a58fb02..6b74a62 100644
+--- a/nbd/client.c
++++ b/nbd/client.c
+@@ -86,9 +86,9 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
+
+ */
+
+-/* Discard length bytes from channel. Return -errno on failure, or
+- * the amount of bytes consumed. */
+-static ssize_t drop_sync(QIOChannel *ioc, size_t size)
++/* Discard length bytes from channel. Return -errno on failure and 0 on
++ * success*/
++static int drop_sync(QIOChannel *ioc, size_t size)
+ {
+ ssize_t ret = 0;
+ char small[1024];
+@@ -96,14 +96,13 @@ static ssize_t drop_sync(QIOChannel *ioc, size_t size)
+
+ buffer = sizeof(small) >= size ? small : g_malloc(MIN(65536, size));
+ while (size > 0) {
+- ssize_t count = read_sync(ioc, buffer, MIN(65536, size));
++ ssize_t count = MIN(65536, size);
++ ret = read_sync(ioc, buffer, MIN(65536, size));
+
+- if (count <= 0) {
++ if (ret < 0) {
+ goto cleanup;
+ }
+- assert(count <= size);
+ size -= count;
+- ret += count;
+ }
+
+ cleanup:
+@@ -136,12 +135,12 @@ static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
+ stl_be_p(&req.option, opt);
+ stl_be_p(&req.length, len);
+
+- if (write_sync(ioc, &req, sizeof(req)) != sizeof(req)) {
++ if (write_sync(ioc, &req, sizeof(req)) < 0) {
+ error_setg(errp, "Failed to send option request header");
+ return -1;
+ }
+
+- if (len && write_sync(ioc, (char *) data, len) != len) {
++ if (len && write_sync(ioc, (char *) data, len) < 0) {
+ error_setg(errp, "Failed to send option request data");
+ return -1;
+ }
+@@ -170,7 +169,7 @@ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
+ nbd_opt_reply *reply, Error **errp)
+ {
+ QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
+- if (read_sync(ioc, reply, sizeof(*reply)) != sizeof(*reply)) {
++ if (read_sync(ioc, reply, sizeof(*reply)) < 0) {
+ error_setg(errp, "failed to read option reply");
+ nbd_send_opt_abort(ioc);
+ return -1;
+@@ -219,7 +218,7 @@ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
+ goto cleanup;
+ }
+ msg = g_malloc(reply->length + 1);
+- if (read_sync(ioc, msg, reply->length) != reply->length) {
++ if (read_sync(ioc, msg, reply->length) < 0) {
+ error_setg(errp, "failed to read option error message");
+ goto cleanup;
+ }
+@@ -321,7 +320,7 @@ static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+- if (read_sync(ioc, &namelen, sizeof(namelen)) != sizeof(namelen)) {
++ if (read_sync(ioc, &namelen, sizeof(namelen)) < 0) {
+ error_setg(errp, "failed to read option name length");
+ nbd_send_opt_abort(ioc);
+ return -1;
+@@ -334,7 +333,7 @@ static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
+ return -1;
+ }
+ if (namelen != strlen(want)) {
+- if (drop_sync(ioc, len) != len) {
++ if (drop_sync(ioc, len) < 0) {
+ error_setg(errp, "failed to skip export name with wrong length");
+ nbd_send_opt_abort(ioc);
+ return -1;
+@@ -343,14 +342,14 @@ static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match,
+ }
+
+ assert(namelen < sizeof(name));
+- if (read_sync(ioc, name, namelen) != namelen) {
++ if (read_sync(ioc, name, namelen) < 0) {
+ error_setg(errp, "failed to read export name");
+ nbd_send_opt_abort(ioc);
+ return -1;
+ }
+ name[namelen] = '\0';
+ len -= namelen;
+- if (drop_sync(ioc, len) != len) {
++ if (drop_sync(ioc, len) < 0) {
+ error_setg(errp, "failed to read export description");
+ nbd_send_opt_abort(ioc);
+ return -1;
+@@ -477,7 +476,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ goto fail;
+ }
+
+- if (read_sync(ioc, buf, 8) != 8) {
++ if (read_sync(ioc, buf, 8) < 0) {
+ error_setg(errp, "Failed to read data");
+ goto fail;
+ }
+@@ -503,7 +502,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ goto fail;
+ }
+
+- if (read_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
++ if (read_sync(ioc, &magic, sizeof(magic)) < 0) {
+ error_setg(errp, "Failed to read magic");
+ goto fail;
+ }
+@@ -515,8 +514,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ uint16_t globalflags;
+ bool fixedNewStyle = false;
+
+- if (read_sync(ioc, &globalflags, sizeof(globalflags)) !=
+- sizeof(globalflags)) {
++ if (read_sync(ioc, &globalflags, sizeof(globalflags)) < 0) {
+ error_setg(errp, "Failed to read server flags");
+ goto fail;
+ }
+@@ -534,8 +532,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ }
+ /* client requested flags */
+ clientflags = cpu_to_be32(clientflags);
+- if (write_sync(ioc, &clientflags, sizeof(clientflags)) !=
+- sizeof(clientflags)) {
++ if (write_sync(ioc, &clientflags, sizeof(clientflags)) < 0) {
+ error_setg(errp, "Failed to send clientflags field");
+ goto fail;
+ }
+@@ -573,13 +570,13 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ }
+
+ /* Read the response */
+- if (read_sync(ioc, &s, sizeof(s)) != sizeof(s)) {
++ if (read_sync(ioc, &s, sizeof(s)) < 0) {
+ error_setg(errp, "Failed to read export length");
+ goto fail;
+ }
+ *size = be64_to_cpu(s);
+
+- if (read_sync(ioc, flags, sizeof(*flags)) != sizeof(*flags)) {
++ if (read_sync(ioc, flags, sizeof(*flags)) < 0) {
+ error_setg(errp, "Failed to read export flags");
+ goto fail;
+ }
+@@ -596,14 +593,14 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ goto fail;
+ }
+
+- if (read_sync(ioc, &s, sizeof(s)) != sizeof(s)) {
++ if (read_sync(ioc, &s, sizeof(s)) < 0) {
+ error_setg(errp, "Failed to read export length");
+ goto fail;
+ }
+ *size = be64_to_cpu(s);
+ TRACE("Size is %" PRIu64, *size);
+
+- if (read_sync(ioc, &oldflags, sizeof(oldflags)) != sizeof(oldflags)) {
++ if (read_sync(ioc, &oldflags, sizeof(oldflags)) < 0) {
+ error_setg(errp, "Failed to read export flags");
+ goto fail;
+ }
+@@ -619,7 +616,7 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags,
+ }
+
+ TRACE("Size is %" PRIu64 ", export flags %" PRIx16, *size, *flags);
+- if (zeroes && drop_sync(ioc, 124) != 124) {
++ if (zeroes && drop_sync(ioc, 124) < 0) {
+ error_setg(errp, "Failed to read reserved block");
+ goto fail;
+ }
+@@ -744,7 +741,6 @@ int nbd_disconnect(int fd)
+ ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request)
+ {
+ uint8_t buf[NBD_REQUEST_SIZE];
+- ssize_t ret;
+
+ TRACE("Sending request to server: "
+ "{ .from = %" PRIu64", .len = %" PRIu32 ", .handle = %" PRIu64
+@@ -759,16 +755,7 @@ ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request)
+ stq_be_p(buf + 16, request->from);
+ stl_be_p(buf + 24, request->len);
+
+- ret = write_sync(ioc, buf, sizeof(buf));
+- if (ret < 0) {
+- return ret;
+- }
+-
+- if (ret != sizeof(buf)) {
+- LOG("writing to socket failed");
+- return -EINVAL;
+- }
+- return 0;
++ return write_sync(ioc, buf, sizeof(buf));
+ }
+
+ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply)
+@@ -777,7 +764,7 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply)
+ uint32_t magic;
+ ssize_t ret;
+
+- ret = read_sync(ioc, buf, sizeof(buf));
++ ret = read_sync_eof(ioc, buf, sizeof(buf));
+ if (ret <= 0) {
+ return ret;
+ }
+diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
+index f43d990..e6bbc7c 100644
+--- a/nbd/nbd-internal.h
++++ b/nbd/nbd-internal.h
+@@ -94,7 +94,13 @@
+ #define NBD_ENOSPC 28
+ #define NBD_ESHUTDOWN 108
+
+-static inline ssize_t read_sync(QIOChannel *ioc, void *buffer, size_t size)
++/* read_sync_eof
++ * Tries to read @size bytes from @ioc. Returns number of bytes actually read.
++ * May return a value >= 0 and < size only on EOF, i.e. when iteratively called
++ * qio_channel_readv() returns 0. So, there are no needs to call read_sync_eof
++ * iteratively.
++ */
++static inline ssize_t read_sync_eof(QIOChannel *ioc, void *buffer, size_t size)
+ {
+ struct iovec iov = { .iov_base = buffer, .iov_len = size };
+ /* Sockets are kept in blocking mode in the negotiation phase. After
+@@ -105,12 +111,32 @@ static inline ssize_t read_sync(QIOChannel *ioc, void *buffer, size_t size)
+ return nbd_wr_syncv(ioc, &iov, 1, size, true);
+ }
+
+-static inline ssize_t write_sync(QIOChannel *ioc, const void *buffer,
+- size_t size)
++/* read_sync
++ * Reads @size bytes from @ioc. Returns 0 on success.
++ */
++static inline int read_sync(QIOChannel *ioc, void *buffer, size_t size)
++{
++ ssize_t ret = read_sync_eof(ioc, buffer, size);
++
++ if (ret >= 0 && ret != size) {
++ ret = -EINVAL;
++ }
++
++ return ret < 0 ? ret : 0;
++}
++
++/* write_sync
++ * Writes @size bytes to @ioc. Returns 0 on success.
++ */
++static inline int write_sync(QIOChannel *ioc, const void *buffer, size_t size)
+ {
+ struct iovec iov = { .iov_base = (void *) buffer, .iov_len = size };
+
+- return nbd_wr_syncv(ioc, &iov, 1, size, false);
++ ssize_t ret = nbd_wr_syncv(ioc, &iov, 1, size, false);
++
++ assert(ret < 0 || ret == size);
++
++ return ret < 0 ? ret : 0;
+ }
+
+ struct NBDTLSHandshakeData {
+diff --git a/nbd/server.c b/nbd/server.c
+index a98bb21..b44cbe6 100644
+--- a/nbd/server.c
++++ b/nbd/server.c
+@@ -112,7 +112,7 @@ static gboolean nbd_negotiate_continue(QIOChannel *ioc,
+ return TRUE;
+ }
+
+-static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
++static int nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
+ {
+ ssize_t ret;
+ guint watch;
+@@ -130,8 +130,7 @@ static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
+
+ }
+
+-static ssize_t nbd_negotiate_write(QIOChannel *ioc, const void *buffer,
+- size_t size)
++static int nbd_negotiate_write(QIOChannel *ioc, const void *buffer, size_t size)
+ {
+ ssize_t ret;
+ guint watch;
+@@ -148,24 +147,24 @@ static ssize_t nbd_negotiate_write(QIOChannel *ioc, const void *buffer,
+ return ret;
+ }
+
+-static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
++static int nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
+ {
+- ssize_t ret, dropped = size;
++ ssize_t ret;
+ uint8_t *buffer = g_malloc(MIN(65536, size));
+
+ while (size > 0) {
+- ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
++ size_t count = MIN(65536, size);
++ ret = nbd_negotiate_read(ioc, buffer, count);
+ if (ret < 0) {
+ g_free(buffer);
+ return ret;
+ }
+
+- assert(ret <= size);
+- size -= ret;
++ size -= count;
+ }
+
+ g_free(buffer);
+- return dropped;
++ return 0;
+ }
+
+ /* Basic flow for negotiation
+@@ -206,22 +205,22 @@ static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
+ type, opt, len);
+
+ magic = cpu_to_be64(NBD_REP_MAGIC);
+- if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
++ if (nbd_negotiate_write(ioc, &magic, sizeof(magic)) < 0) {
+ LOG("write failed (rep magic)");
+ return -EINVAL;
+ }
+ opt = cpu_to_be32(opt);
+- if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
++ if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) < 0) {
+ LOG("write failed (rep opt)");
+ return -EINVAL;
+ }
+ type = cpu_to_be32(type);
+- if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
++ if (nbd_negotiate_write(ioc, &type, sizeof(type)) < 0) {
+ LOG("write failed (rep type)");
+ return -EINVAL;
+ }
+ len = cpu_to_be32(len);
+- if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
++ if (nbd_negotiate_write(ioc, &len, sizeof(len)) < 0) {
+ LOG("write failed (rep data length)");
+ return -EINVAL;
+ }
+@@ -256,7 +255,7 @@ nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
+ if (ret < 0) {
+ goto out;
+ }
+- if (nbd_negotiate_write(ioc, msg, len) != len) {
++ if (nbd_negotiate_write(ioc, msg, len) < 0) {
+ LOG("write failed (error message)");
+ ret = -EIO;
+ } else {
+@@ -287,15 +286,15 @@ static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp)
+ }
+
+ len = cpu_to_be32(name_len);
+- if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
++ if (nbd_negotiate_write(ioc, &len, sizeof(len)) < 0) {
+ LOG("write failed (name length)");
+ return -EINVAL;
+ }
+- if (nbd_negotiate_write(ioc, name, name_len) != name_len) {
++ if (nbd_negotiate_write(ioc, name, name_len) < 0) {
+ LOG("write failed (name buffer)");
+ return -EINVAL;
+ }
+- if (nbd_negotiate_write(ioc, desc, desc_len) != desc_len) {
++ if (nbd_negotiate_write(ioc, desc, desc_len) < 0) {
+ LOG("write failed (description buffer)");
+ return -EINVAL;
+ }
+@@ -309,7 +308,7 @@ static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length)
+ NBDExport *exp;
+
+ if (length) {
+- if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
++ if (nbd_negotiate_drop_sync(client->ioc, length) < 0) {
+ return -EIO;
+ }
+ return nbd_negotiate_send_rep_err(client->ioc,
+@@ -340,7 +339,7 @@ static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length)
+ LOG("Bad length received");
+ goto fail;
+ }
+- if (nbd_negotiate_read(client->ioc, name, length) != length) {
++ if (nbd_negotiate_read(client->ioc, name, length) < 0) {
+ LOG("read failed");
+ goto fail;
+ }
+@@ -373,7 +372,7 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
+ TRACE("Setting up TLS");
+ ioc = client->ioc;
+ if (length) {
+- if (nbd_negotiate_drop_sync(ioc, length) != length) {
++ if (nbd_negotiate_drop_sync(ioc, length) < 0) {
+ return NULL;
+ }
+ nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
+@@ -437,8 +436,7 @@ static int nbd_negotiate_options(NBDClient *client)
+ ... Rest of request
+ */
+
+- if (nbd_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
+- sizeof(flags)) {
++ if (nbd_negotiate_read(client->ioc, &flags, sizeof(flags)) < 0) {
+ LOG("read failed");
+ return -EIO;
+ }
+@@ -464,8 +462,7 @@ static int nbd_negotiate_options(NBDClient *client)
+ uint32_t clientflags, length;
+ uint64_t magic;
+
+- if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) !=
+- sizeof(magic)) {
++ if (nbd_negotiate_read(client->ioc, &magic, sizeof(magic)) < 0) {
+ LOG("read failed");
+ return -EINVAL;
+ }
+@@ -476,14 +473,14 @@ static int nbd_negotiate_options(NBDClient *client)
+ }
+
+ if (nbd_negotiate_read(client->ioc, &clientflags,
+- sizeof(clientflags)) != sizeof(clientflags)) {
++ sizeof(clientflags)) < 0)
++ {
+ LOG("read failed");
+ return -EINVAL;
+ }
+ clientflags = be32_to_cpu(clientflags);
+
+- if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
+- sizeof(length)) {
++ if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) < 0) {
+ LOG("read failed");
+ return -EINVAL;
+ }
+@@ -513,7 +510,7 @@ static int nbd_negotiate_options(NBDClient *client)
+ return -EINVAL;
+
+ default:
+- if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
++ if (nbd_negotiate_drop_sync(client->ioc, length) < 0) {
+ return -EIO;
+ }
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+@@ -551,7 +548,7 @@ static int nbd_negotiate_options(NBDClient *client)
+ return nbd_negotiate_handle_export_name(client, length);
+
+ case NBD_OPT_STARTTLS:
+- if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
++ if (nbd_negotiate_drop_sync(client->ioc, length) < 0) {
+ return -EIO;
+ }
+ if (client->tlscreds) {
+@@ -570,7 +567,7 @@ static int nbd_negotiate_options(NBDClient *client)
+ }
+ break;
+ default:
+- if (nbd_negotiate_drop_sync(client->ioc, length) != length) {
++ if (nbd_negotiate_drop_sync(client->ioc, length) < 0) {
+ return -EIO;
+ }
+ ret = nbd_negotiate_send_rep_err(client->ioc,
+@@ -659,12 +656,12 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
+ TRACE("TLS cannot be enabled with oldstyle protocol");
+ goto fail;
+ }
+- if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
++ if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) < 0) {
+ LOG("write failed");
+ goto fail;
+ }
+ } else {
+- if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
++ if (nbd_negotiate_write(client->ioc, buf, 18) < 0) {
+ LOG("write failed");
+ goto fail;
+ }
+@@ -679,7 +676,7 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
+ stq_be_p(buf + 18, client->exp->size);
+ stw_be_p(buf + 26, client->exp->nbdflags | myflags);
+ len = client->no_zeroes ? 10 : sizeof(buf) - 18;
+- if (nbd_negotiate_write(client->ioc, buf + 18, len) != len) {
++ if (nbd_negotiate_write(client->ioc, buf + 18, len) < 0) {
+ LOG("write failed");
+ goto fail;
+ }
+@@ -702,11 +699,6 @@ static ssize_t nbd_receive_request(QIOChannel *ioc, NBDRequest *request)
+ return ret;
+ }
+
+- if (ret != sizeof(buf)) {
+- LOG("read failed");
+- return -EINVAL;
+- }
+-
+ /* Request
+ [ 0 .. 3] magic (NBD_REQUEST_MAGIC)
+ [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
+@@ -737,7 +729,6 @@ static ssize_t nbd_receive_request(QIOChannel *ioc, NBDRequest *request)
+ static ssize_t nbd_send_reply(QIOChannel *ioc, NBDReply *reply)
+ {
+ uint8_t buf[NBD_REPLY_SIZE];
+- ssize_t ret;
+
+ reply->error = system_errno_to_nbd_errno(reply->error);
+
+@@ -754,16 +745,7 @@ static ssize_t nbd_send_reply(QIOChannel *ioc, NBDReply *reply)
+ stl_be_p(buf + 4, reply->error);
+ stq_be_p(buf + 8, reply->handle);
+
+- ret = write_sync(ioc, buf, sizeof(buf));
+- if (ret < 0) {
+- return ret;
+- }
+-
+- if (ret != sizeof(buf)) {
+- LOG("writing to socket failed");
+- return -EINVAL;
+- }
+- return 0;
++ return write_sync(ioc, buf, sizeof(buf));
+ }
+
+ #define MAX_NBD_REQUESTS 16
+@@ -1067,7 +1049,7 @@ static ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
+ rc = nbd_send_reply(client->ioc, reply);
+ if (rc >= 0) {
+ ret = write_sync(client->ioc, req->data, len);
+- if (ret != len) {
++ if (ret < 0) {
+ rc = -EIO;
+ }
+ }
+@@ -1141,7 +1123,7 @@ static ssize_t nbd_co_receive_request(NBDRequestData *req,
+ if (request->type == NBD_CMD_WRITE) {
+ TRACE("Reading %" PRIu32 " byte(s)", request->len);
+
+- if (read_sync(client->ioc, req->data, request->len) != request->len) {
++ if (read_sync(client->ioc, req->data, request->len) < 0) {
+ LOG("reading from socket failed");
+ rc = -EIO;
+ goto out;
+--
+1.8.3.1
+