[PULL v2 00/13] NBD patches for 2023-09-07

[PULL v2 00/13] NBD patches for 2023-09-07

[Eric Blake]

The following changes since commit 03a3a62fbd0aa5227e978eef3c67d3978aec9e5f:

  Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging (2023-09-07 10:29:06 -0400)

are available in the Git repository at:

  https://repo.or.cz/qemu/ericb.git tags/pull-nbd-2023-09-07-v2

for you to fetch changes up to 35e087de085cd6cf7e4c64c9b59b62c37ddcd1bd:

  qemu-nbd: document -v behavior in respect to --fork in man (2023-09-08 07:21:43 -0500)

v2: fix build failure when stderr is macro (only posting changed patch to list)

----------------------------------------------------------------
NBD patches for 2023-09-07

- Andrey Drobyshev - fix regression in iotest 197 under -nbd
- Stefan Hajnoczi - allow coroutine read and write context to split
across threads
- Philippe Mathieu-Daudé - remove a VLA allocation
- Denis V. Lunev - fix regression in iotest 233 with qemu-nbd -v --fork

----------------------------------------------------------------
Andrey Drobyshev (1):
      qemu-iotests/197: use more generic commands for formats other than qcow2

Denis V. Lunev (7):
      qemu-nbd: improve error message for dup2 error
      qemu-nbd: define struct NbdClientOpts when HAVE_NBD_DEVICE is not defined
      qemu-nbd: move srcpath into struct NbdClientOpts
      qemu-nbd: put saddr into into struct NbdClientOpts
      qemu-nbd: invent nbd_client_release_pipe() helper
      qemu-nbd: Restore "qemu-nbd -v --fork" output
      qemu-nbd: document -v behavior in respect to --fork in man

Philippe Mathieu-Daudé (1):
      util/iov: Avoid dynamic stack allocation

Stefan Hajnoczi (4):
      nbd: drop unused nbd_receive_negotiate() aio_context argument
      nbd: drop unused nbd_start_negotiate() aio_context argument
      io: check there are no qio_channel_yield() coroutines during ->finalize()
      io: follow coroutine AioContext in qio_channel_yield()

 docs/tools/qemu-nbd.rst          |   4 +-
 include/block/nbd.h              |   3 +-
 include/io/channel-util.h        |  23 +++++++
 include/io/channel.h             |  69 +++++++++-----------
 include/qemu/vhost-user-server.h |   1 +
 block/nbd.c                      |  11 +---
 io/channel-command.c             |  10 ++-
 io/channel-file.c                |   9 ++-
 io/channel-null.c                |   3 +-
 io/channel-socket.c              |   9 ++-
 io/channel-tls.c                 |   6 +-
 io/channel-util.c                |  24 +++++++
 io/channel.c                     | 124 ++++++++++++++++++++++++++----------
 migration/channel-block.c        |   3 +-
 migration/rdma.c                 |  25 ++++----
 nbd/client-connection.c          |   3 +-
 nbd/client.c                     |  14 ++---
 nbd/server.c                     |  14 +----
 qemu-nbd.c                       | 133 +++++++++++++++++++++------------------
 scsi/qemu-pr-helper.c            |   4 +-
 util/iov.c                       |   2 +-
 util/vhost-user-server.c         |  27 +++++---
 tests/qemu-iotests/197           |   8 +--
 tests/qemu-iotests/197.out       |  18 +++---
 24 files changed, 328 insertions(+), 219 deletions(-)

-- 
2.41.0

[PULL v2 12/13] qemu-nbd: Restore "qemu-nbd -v --fork" output

[Eric Blake]

From: "Denis V. Lunev" <den@openvz.org>

Closing stderr earlier is good for daemonized qemu-nbd under ssh
earlier, but breaks the case where -v is being used to track what is
happening in the server, as in iotest 233.

When we know we are verbose, we should preserve original stderr and
restore it once the setup stage is done. This commit restores the
original behavior with -v option. In this case original output
inside the test is kept intact.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: Hanna Reitz <hreitz@redhat.com>
CC: Mike Maslenkin <mike.maslenkin@gmail.com>
Fixes: 5c56dd27a2 ("qemu-nbd: fix regression with qemu-nbd --fork run over ssh")
Message-ID: <20230906093210.339585-7-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
[eblake: fix build by avoiding stderr as struct member name]
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 qemu-nbd.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 7c4e22def17..30eeb6f3c75 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -255,18 +255,23 @@ struct NbdClientOpts {
     char *device;
     char *srcpath;
     SocketAddress *saddr;
+    int old_stderr;
     bool fork_process;
     bool verbose;
 };

-static void nbd_client_release_pipe(void)
+static void nbd_client_release_pipe(int old_stderr)
 {
     /* Close stderr so that the qemu-nbd process exits.  */
-    if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0) {
+    if (dup2(old_stderr, STDERR_FILENO) < 0) {
         error_report("Could not release pipe to parent: %s",
                      strerror(errno));
         exit(EXIT_FAILURE);
     }
+    if (old_stderr != STDOUT_FILENO && close(old_stderr) < 0) {
+        error_report("Could not release qemu-nbd: %s", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
 }

 #if HAVE_NBD_DEVICE
@@ -332,7 +337,7 @@ static void *nbd_client_thread(void *arg)
         fprintf(stderr, "NBD device %s is now connected to %s\n",
                 opts->device, opts->srcpath);
     } else {
-        nbd_client_release_pipe();
+        nbd_client_release_pipe(opts->old_stderr);
     }

     if (nbd_client(fd) < 0) {
@@ -597,6 +602,7 @@ int main(int argc, char **argv)
         .device = NULL,
         .srcpath = NULL,
         .saddr = NULL,
+        .old_stderr = STDOUT_FILENO,
     };

 #ifdef CONFIG_POSIX
@@ -951,6 +957,16 @@ int main(int argc, char **argv)

             close(stderr_fd[0]);

+            /* Remember parent's stderr if we will be restoring it. */
+            if (opts.verbose /* fork_process is set */) {
+                opts.old_stderr = dup(STDERR_FILENO);
+                if (opts.old_stderr < 0) {
+                    error_report("Could not dup original stderr: %s",
+                                 strerror(errno));
+                    exit(EXIT_FAILURE);
+                }
+            }
+
             ret = qemu_daemon(1, 0);
             saved_errno = errno;    /* dup2 will overwrite error below */

@@ -1181,7 +1197,7 @@ int main(int argc, char **argv)
     }

     if (opts.fork_process) {
-        nbd_client_release_pipe();
+        nbd_client_release_pipe(opts.old_stderr);
     }

     state = RUNNING;
-- 
2.41.0

Re: [PULL v2 00/13] NBD patches for 2023-09-07

[Stefan Hajnoczi]

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Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/8.2 for any user-visible changes.

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