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[libvirt] [PATCH v7 2/6] add fuse support for libvirt lxc



this patch addes fuse support for libvirt lxc.
we can use fuse filesystem to generate sysinfo dynamically,
So we can isolate /proc/meminfo,cpuinfo and so on through
fuse filesystem.

we mount fuse filesystem for every container.
the mount name is libvirt,mount point is
localstatedir/run/libvirt/lxc/containername.

Signed-off-by: Gao feng <gaofeng cn fujitsu com>
---
 po/POTFILES.in           |    1 +
 src/Makefile.am          |    9 ++-
 src/lxc/lxc_cgroup.c     |    1 +
 src/lxc/lxc_container.h  |    3 +
 src/lxc/lxc_controller.c |   26 ++++++++
 src/lxc/lxc_fuse.c       |  157 ++++++++++++++++++++++++++++++++++++++++++++++
 src/lxc/lxc_fuse.h       |   40 ++++++++++++
 src/lxc/lxc_process.c    |    1 +
 8 files changed, 236 insertions(+), 2 deletions(-)
 create mode 100644 src/lxc/lxc_fuse.c
 create mode 100644 src/lxc/lxc_fuse.h

diff --git a/po/POTFILES.in b/po/POTFILES.in
index 9768528..0199d6f 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -50,6 +50,7 @@ src/locking/lock_driver_sanlock.c
 src/locking/lock_manager.c
 src/locking/sanlock_helper.c
 src/lxc/lxc_cgroup.c
+src/lxc/lxc_fuse.c
 src/lxc/lxc_container.c
 src/lxc/lxc_conf.c
 src/lxc/lxc_controller.c
diff --git a/src/Makefile.am b/src/Makefile.am
index 1f32263..4b8e6c0 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -413,6 +413,7 @@ LXC_DRIVER_SOURCES =						\
 		lxc/lxc_domain.c lxc/lxc_domain.h		\
 		lxc/lxc_monitor.c lxc/lxc_monitor.h		\
 		lxc/lxc_process.c lxc/lxc_process.h		\
+		lxc/lxc_fuse.c lxc/lxc_fuse.h			\
 		lxc/lxc_driver.c lxc/lxc_driver.h
 
 LXC_CONTROLLER_SOURCES =					\
@@ -421,6 +422,7 @@ LXC_CONTROLLER_SOURCES =					\
 		lxc/lxc_conf.c lxc/lxc_conf.h			\
 		lxc/lxc_container.c lxc/lxc_container.h		\
 		lxc/lxc_cgroup.c lxc/lxc_cgroup.h		\
+		lxc/lxc_fuse.c lxc/lxc_fuse.h			\
 		lxc/lxc_controller.c
 
 SECURITY_DRIVER_APPARMOR_HELPER_SOURCES =			\
@@ -911,8 +913,9 @@ endif
 
 libvirt_driver_lxc_impl_la_CFLAGS = \
 		$(LIBNL_CFLAGS) \
+		$(FUSE_CFLAGS) \
 		-I$(top_srcdir)/src/conf $(AM_CFLAGS)
-libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS)
+libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS) $(FUSE_LIBS)
 if HAVE_LIBBLKID
 libvirt_driver_lxc_impl_la_CFLAGS += $(BLKID_CFLAGS)
 libvirt_driver_lxc_impl_la_LIBADD += $(BLKID_LIBS)
@@ -1678,6 +1681,7 @@ libvirt_lxc_SOURCES =						\
 libvirt_lxc_LDFLAGS = $(WARN_CFLAGS) $(AM_LDFLAGS)
 libvirt_lxc_LDADD =			\
 		$(NUMACTL_LIBS) \
+		$(FUSE_LIBS) \
 		libvirt-net-rpc-server.la \
 		libvirt-net-rpc.la \
 		libvirt_security_manager.la \
@@ -1696,7 +1700,8 @@ endif
 libvirt_lxc_CFLAGS =				\
 		-I$(top_srcdir)/src/conf	\
 		$(AM_CFLAGS)                    \
-		$(LIBNL_CFLAGS)
+		$(LIBNL_CFLAGS)			\
+		$(FUSE_CFLAGS)
 if HAVE_LIBBLKID
 libvirt_lxc_CFLAGS += $(BLKID_CFLAGS)
 libvirt_lxc_LDADD += $(BLKID_LIBS)
diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c
index bdfaa54..9a5ba1a 100644
--- a/src/lxc/lxc_cgroup.c
+++ b/src/lxc/lxc_cgroup.c
@@ -163,6 +163,7 @@ static int virLXCCgroupSetupDeviceACL(virDomainDefPtr def,
         {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_URANDOM},
         {'c', LXC_DEV_MAJ_TTY, LXC_DEV_MIN_TTY},
         {'c', LXC_DEV_MAJ_TTY, LXC_DEV_MIN_PTMX},
+        {'c', LXC_DEV_MAJ_FUSE, LXC_DEV_MIN_FUSE},
         {0,   0, 0}};
 
     rc = virCgroupDenyAllDevices(cgroup);
diff --git a/src/lxc/lxc_container.h b/src/lxc/lxc_container.h
index b1adacb..c8c70e0 100644
--- a/src/lxc/lxc_container.h
+++ b/src/lxc/lxc_container.h
@@ -46,6 +46,9 @@ enum {
 
 # define LXC_DEV_MAJ_PTY     136
 
+# define LXC_DEV_MAJ_FUSE    10
+# define LXC_DEV_MIN_FUSE    229
+
 int lxcContainerSendContinue(int control);
 int lxcContainerWaitForContinue(int control);
 
diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
index a41c903..f0d28f8 100644
--- a/src/lxc/lxc_controller.c
+++ b/src/lxc/lxc_controller.c
@@ -60,6 +60,7 @@
 #include "lxc_container.h"
 #include "lxc_cgroup.h"
 #include "lxc_protocol.h"
+#include "lxc_fuse.h"
 #include "virnetdev.h"
 #include "virnetdevveth.h"
 #include "memory.h"
@@ -1245,6 +1246,28 @@ cleanup:
     return ret;
 }
 
+static int
+virLXCControllerSetupFuse(virLXCControllerPtr ctrl)
+{
+    int try = 0;
+    virThread thread;
+    if (virThreadCreate(&thread, true, lxcRegisterFuse,
+                        (void *)ctrl->def) < 0)
+        return -1;
+    /*
+     * because libvirt_lxc may use fuse filesystem before fuse being
+     * mounted by the thread. so wait 3 seconds in libvirt_lxc. if fuse
+     * is not mounted in 3 seconds, libvirt_lxc will exit.
+     */
+    while (try++ < 2) {
+        if (lxcRegisterFuseSuccess())
+            return 0;
+
+        sleep(1);
+    }
+
+    return -1;
+}
 
 static int
 virLXCControllerSetupConsoles(virLXCControllerPtr ctrl,
@@ -1388,6 +1411,9 @@ virLXCControllerRun(virLXCControllerPtr ctrl)
     if (virLXCControllerSetupDevPTS(ctrl) < 0)
         goto cleanup;
 
+    if (virLXCControllerSetupFuse(ctrl) < 0)
+        goto cleanup;
+
     if (virLXCControllerSetupConsoles(ctrl, containerTTYPaths) < 0)
         goto cleanup;
 
diff --git a/src/lxc/lxc_fuse.c b/src/lxc/lxc_fuse.c
new file mode 100644
index 0000000..42107d7
--- /dev/null
+++ b/src/lxc/lxc_fuse.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2012 Fujitsu Limited.
+ *
+ * lxc_fuse.c: fuse filesystem support for libvirt lxc
+ *
+ * Authors:
+ *  Gao feng <gaofeng at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <mntent.h>
+
+#include "lxc_fuse.h"
+#include "virterror_internal.h"
+#include "logging.h"
+
+#define VIR_FROM_THIS VIR_FROM_LXC
+
+#if HAVE_FUSE
+
+static int lxcProcGetattr(const char *path, struct stat *stbuf)
+{
+    int res = 0;
+
+    memset(stbuf, 0, sizeof(struct stat));
+
+    if (STREQ(path, "/")) {
+        stbuf->st_mode = S_IFDIR | 0755;
+        stbuf->st_nlink = 2;
+    } else {
+        res = -ENOENT;
+    }
+
+    return res;
+}
+
+static int lxcProcReaddir(const char *path, void *buf,
+                          fuse_fill_dir_t filler,
+                          off_t offset ATTRIBUTE_UNUSED,
+                          struct fuse_file_info *fi ATTRIBUTE_UNUSED)
+{
+    if (!STREQ(path, "/"))
+        return -ENOENT;
+
+    filler(buf, ".", NULL, 0);
+    filler(buf, "..", NULL, 0);
+
+    return 0;
+}
+
+static int lxcProcOpen(const char *path ATTRIBUTE_UNUSED,
+                       struct fuse_file_info *fi ATTRIBUTE_UNUSED)
+{
+    return -ENOENT;
+}
+
+static int lxcProcRead(const char *path ATTRIBUTE_UNUSED,
+                       char *buf ATTRIBUTE_UNUSED,
+                       size_t size ATTRIBUTE_UNUSED,
+                       off_t offset ATTRIBUTE_UNUSED,
+                       struct fuse_file_info *fi ATTRIBUTE_UNUSED)
+{
+    return -ENOENT;
+}
+
+static struct fuse_operations lxcProcOper = {
+    .getattr = lxcProcGetattr,
+    .readdir = lxcProcReaddir,
+    .open    = lxcProcOpen,
+    .read    = lxcProcRead,
+};
+
+void lxcRegisterFuse(void *opaque)
+{
+    int argc = 4;
+    char *argv[argc];
+    char *path = NULL;
+    virDomainDefPtr def = opaque;
+
+    if (virAsprintf(&path, "%s/%s/", LXC_STATE_DIR, def->name) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
+
+    if (virFileMakePath(path) < 0) {
+        virReportSystemError(errno, _("Cannot create %s"), path);
+        goto cleanup;
+    }
+
+    argv[0] = (char *)"libvirt";
+    argv[1] = path;
+    argv[2] = (char *)"-odirect_io";
+    argv[3] = (char *)"-f";
+
+    if (fuse_main(argc, argv, &lxcProcOper, def) < 0)
+        virReportSystemError(errno, "%s", _("Cannot start fuse"));
+
+cleanup:
+    VIR_FREE(path);
+    return;
+}
+
+int lxcRegisterFuseSuccess(void)
+{
+    FILE *procmnt = NULL;
+    struct mntent mntent;
+    char mntbuf[1024];
+    int ret = 0;
+
+    if (!(procmnt = setmntent("/proc/mounts", "r"))) {
+        virReportSystemError(errno, "%s",
+                             _("Failed to read /proc/mounts"));
+        return ret;
+    }
+
+    while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) {
+        VIR_DEBUG("Got %s\n",mntent.mnt_fsname);
+        if (STRNEQ(mntent.mnt_fsname, "libvirt"))
+            continue;
+
+        ret = 1;
+        break;
+    }
+
+    endmntent(procmnt);
+    return ret;
+}
+
+#else
+void lxcRegisterFuse(void *opaque ATTRIBUTE_UNUSED)
+{
+}
+
+int lxcRegisterFuseSuccess(void)
+{
+    return 1;
+}
+#endif
diff --git a/src/lxc/lxc_fuse.h b/src/lxc/lxc_fuse.h
new file mode 100644
index 0000000..5b3689e
--- /dev/null
+++ b/src/lxc/lxc_fuse.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2012 Fujitsu Limited.
+ *
+ * lxc_fuse.c: fuse filesystem support for libvirt lxc
+ *
+ * Authors:
+ *  Gao feng <gaofeng at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LXC_FUSE_H
+#define LXC_FUSE_H
+
+#define FUSE_USE_VERSION 26
+
+#include <config.h>
+#if HAVE_FUSE
+#include <fuse.h>
+#endif
+
+#include "lxc_conf.h"
+#include "util.h"
+#include "memory.h"
+
+extern void lxcRegisterFuse(void *opaque);
+extern int lxcRegisterFuseSuccess(void);
+#endif
diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c
index 079bc3a..a9a0984 100644
--- a/src/lxc/lxc_process.c
+++ b/src/lxc/lxc_process.c
@@ -28,6 +28,7 @@
 #include "lxc_process.h"
 #include "lxc_domain.h"
 #include "lxc_container.h"
+#include "lxc_fuse.h"
 #include "datatypes.h"
 #include "virfile.h"
 #include "virpidfile.h"
-- 
1.7.7.6


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