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virtiofsd: Prevent multiply running with same vhost_user_socket

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virtiofsd can run multiply even if the vhost_user_socket is same path.

  ]# ./virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/tmp/share &
  [1] 244965
  virtio_session_mount: Waiting for vhost-user socket connection...
  ]# ./virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/tmp/share &
  [2] 244966
  virtio_session_mount: Waiting for vhost-user socket connection...
  ]#

The user will get confused about the situation and maybe the cause of the
unexpected problem. So it's better to prevent the multiple running.

Create a regular file under localstatedir directory to exclude the
vhost_user_socket. To create and lock the file, use qemu_write_pidfile()
because the API has some sanity checks and file lock.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  Applied fixes from Stefan's review and moved osdep include
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Masayoshi Mizuma 2019-08-13 16:06:45 -04:00 committed by Dr. David Alan Gilbert
parent 18a69cbbb6
commit 96814800d2
2 changed files with 49 additions and 1 deletions
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1
tools/virtiofsd/fuse_lowlevel.c
View File

@ -18,6 +18,7 @@
#include <assert.h>
#include <errno.h>
#include <glib.h>
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>

49
tools/virtiofsd/fuse_virtio.c
View File

@ -13,11 +13,12 @@
#include "qemu/osdep.h"
#include "qemu/iov.h"
#include "fuse_virtio.h"
#include "qapi/error.h"
#include "fuse_i.h"
#include "standard-headers/linux/fuse.h"
#include "fuse_misc.h"
#include "fuse_opt.h"
#include "fuse_virtio.h"
#include <assert.h>
#include <errno.h>
@ -743,6 +744,42 @@ int virtio_loop(struct fuse_session *se)
return 0;
}
static void strreplace(char *s, char old, char new)
{
for (; *s; ++s) {
if (*s == old) {
*s = new;
}
}
}
static bool fv_socket_lock(struct fuse_session *se)
{
g_autofree gchar *sk_name = NULL;
g_autofree gchar *pidfile = NULL;
g_autofree gchar *dir = NULL;
Error *local_err = NULL;
dir = qemu_get_local_state_pathname("run/virtiofsd");
if (g_mkdir_with_parents(dir, S_IRWXU) < 0) {
fuse_log(FUSE_LOG_ERR, "%s: Failed to create directory %s: %s",
__func__, dir, strerror(errno));
return false;
}
sk_name = g_strdup(se->vu_socket_path);
strreplace(sk_name, '/', '.');
pidfile = g_strdup_printf("%s/%s.pid", dir, sk_name);
if (!qemu_write_pidfile(pidfile, &local_err)) {
error_report_err(local_err);
return false;
}
return true;
}
static int fv_create_listen_socket(struct fuse_session *se)
{
struct sockaddr_un un;
@ -758,6 +795,16 @@ static int fv_create_listen_socket(struct fuse_session *se)
return -1;
}
if (!strlen(se->vu_socket_path)) {
fuse_log(FUSE_LOG_ERR, "Socket path is empty\n");
return -1;
}
/* Check the vu_socket_path is already used */
if (!fv_socket_lock(se)) {
return -1;
}
/*
* Create the Unix socket to communicate with qemu
* based on QEMU's vhost-user-bridge