From fd123e372472179657da738e52e87897d0508812 Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Wed, 27 Mar 2019 17:22:23 +0100

Subject: [PATCH 084/163] qemu-nbd: Fail earlier for -c/-d on non-linux

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20190327172308.31077-11-jsnow@redhat.com>

Patchwork-id: 85173

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 10/55] qemu-nbd: Fail earlier for -c/-d on non-linux

Bugzilla: 1691009

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

From: Eric Blake <eblake@redhat.com>

Connecting to a /dev/nbdN device is a Linux-specific action.

We were already masking -c and -d from 'qemu-nbd --help' on

non-linux.  However, while -d fails with a sensible error

message, it took hunting through a couple of files to prove

that.  What's more, the code for -c doesn't fail until after

it has created a pthread and tried to open a device - possibly

even printing an error message with %m on a non-Linux platform

in spite of the comment that %m is glibc-specific.  Make the

failure happen sooner, then get rid of stubs that are no

longer needed because of the early exits.

While at it: tweak the blank newlines in --help output to be

consistent, whether or not built on Linux.

Signed-off-by: Eric Blake <eblake@redhat.com>

Message-Id: <20181215135324.152629-7-eblake@redhat.com>

Reviewed-by: Richard W.M. Jones <rjones@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

(cherry picked from commit 3c1fa35d74aabe9c3ab642d2591b087e53d7a616)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 nbd/client.c | 18 +-----------------

 qemu-nbd.c   | 21 +++++++++++++++++++--

 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/nbd/client.c b/nbd/client.c

index e774147..5a03a84 100644

--- a/nbd/client.c

+++ b/nbd/client.c

@@ -1031,23 +1031,7 @@ int nbd_disconnect(int fd)

     return 0;

 }

-#else

-int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info,

-	     Error **errp)

-{

-    error_setg(errp, "nbd_init is only supported on Linux");

-    return -ENOTSUP;

-}

-

-int nbd_client(int fd)

-{

-    return -ENOTSUP;

-}

-int nbd_disconnect(int fd)

-{

-    return -ENOTSUP;

-}

-#endif

+#endif /* __linux__ */

 int nbd_send_request(QIOChannel *ioc, NBDRequest *request)

 {

diff --git a/qemu-nbd.c b/qemu-nbd.c

index 7f078b2..652199c 100644

--- a/qemu-nbd.c

+++ b/qemu-nbd.c

@@ -43,6 +43,12 @@

 #include "trace/control.h"

 #include "qemu-version.h"

+#ifdef __linux__

+#define HAVE_NBD_DEVICE 1

+#else

+#define HAVE_NBD_DEVICE 0

+#endif

+

 #define SOCKET_PATH                "/var/lock/qemu-nbd-%s"

 #define QEMU_NBD_OPT_CACHE         256

 #define QEMU_NBD_OPT_AIO           257

@@ -98,11 +104,11 @@ static void usage(const char *name)

 "                            specify tracing options\n"

 "  --fork                    fork off the server process and exit the parent\n"

 "                            once the server is running\n"

-#ifdef __linux__

+#if HAVE_NBD_DEVICE

+"\n"

 "Kernel NBD client support:\n"

 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"

 "  -d, --disconnect          disconnect the specified device\n"

-"\n"

 #endif

 "\n"

 "Block device options:\n"

@@ -236,6 +242,7 @@ static void termsig_handler(int signum)

 }

+#if HAVE_NBD_DEVICE

 static void *show_parts(void *arg)

 {

     char *device = arg;

@@ -321,6 +328,7 @@ out:

     kill(getpid(), SIGTERM);

     return (void *) EXIT_FAILURE;

 }

+#endif /* HAVE_NBD_DEVICE */

 static int nbd_can_accept(void)

 {

@@ -816,6 +824,12 @@ int main(int argc, char **argv)

         }

     }

+#if !HAVE_NBD_DEVICE

+    if (disconnect || device) {

+        error_report("Kernel /dev/nbdN support not available");

+        exit(EXIT_FAILURE);

+    }

+#else /* HAVE_NBD_DEVICE */

     if (disconnect) {

         int nbdfd = open(argv[optind], O_RDWR);

         if (nbdfd < 0) {

@@ -831,6 +845,7 @@ int main(int argc, char **argv)

         return 0;

     }

+#endif

     if ((device && !verbose) || fork_process) {

         int stderr_fd[2];

@@ -1012,6 +1027,7 @@ int main(int argc, char **argv)

     nbd_export_set_description(exp, export_description);

     if (device) {

+#if HAVE_NBD_DEVICE

         int ret;

         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);

@@ -1019,6 +1035,7 @@ int main(int argc, char **argv)

             error_report("Failed to create client thread: %s", strerror(ret));

             exit(EXIT_FAILURE);

         }

+#endif

     } else {

         /* Shut up GCC warnings.  */

         memset(&client_thread, 0, sizeof(client_thread));

-- 

1.8.3.1