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

@@ -51,6 +51,7 @@ 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

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 =			\
@@ -912,8 +914,9 @@ 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)
@@ -1679,6 +1682,7 @@ libvirt_lxc_SOURCES =						\
 libvirt_lxc_LDFLAGS = $(WARN_CFLAGS) $(AM_LDFLAGS)
 libvirt_lxc_LDADD =			\
 		$(NUMACTL_LIBS) \
+		$(FUSE_LIBS) \
 		libvirt-net-rpc-server.la \
 		libvirt-net-rpc.la \
 		libvirt_security_manager.la \
@@ -1697,7 +1701,8 @@ endif
 libvirt_lxc_CFLAGS =				\
 		-I$(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)

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);

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);
 

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"
@@ -130,6 +131,8 @@ struct _virLXCController {
     virNetServerProgramPtr prog;
     bool inShutdown;
     int timerShutdown;
+
+    virLXCFusePtr fuse;
 };
 
 #include "lxc_controller_dispatch.h"
@@ -242,6 +245,13 @@ static void virLXCControllerConsoleClose(virLXCControllerConsolePtr console)
 }
 
 
+static void
+virLXCControllerFreeFuse(virLXCControllerPtr ctrl)
+{
+    return lxcFreeFuse(&ctrl->fuse);
+}
+
+
 static void virLXCControllerFree(virLXCControllerPtr ctrl)
 {
     size_t i;
@@ -272,6 +282,7 @@ static void virLXCControllerFree(virLXCControllerPtr ctrl)
         virEventRemoveTimeout(ctrl->timerShutdown);
 
     virObjectUnref(ctrl->server);
+    virLXCControllerFreeFuse(ctrl);
 
     VIR_FREE(ctrl);
 }
@@ -1243,6 +1254,12 @@ cleanup:
 }
 
 
+static int
+virLXCControllerSetupFuse(virLXCControllerPtr ctrl)
+{
+    return lxcSetupFuse(&ctrl->fuse, ctrl->def);
+}
+
 static int
 virLXCControllerSetupConsoles(virLXCControllerPtr ctrl,
                               char **containerTTYPaths)
@@ -1405,6 +1422,9 @@ virLXCControllerRun(virLXCControllerPtr ctrl)
     if (virLXCControllerSetupDevPTS(ctrl) < 0)
         goto cleanup;
 
+    if (virLXCControllerSetupFuse(ctrl) < 0)
+        goto cleanup;
+
     if (virLXCControllerSetupConsoles(ctrl, containerTTYPaths) < 0)
         goto cleanup;
 

src/lxc/lxc_fuse.c

@@ -0,0 +1,202 @@
+/*
+ * 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,
+};
+
+static void lxcFuseDestroy(virLXCFusePtr fuse)
+{
+    virMutexLock(&fuse->lock);
+    fuse_unmount(fuse->mountpoint, fuse->ch);
+    fuse_destroy(fuse->fuse);
+    fuse->fuse = NULL;
+    virMutexUnlock(&fuse->lock);
+}
+
+static void lxcFuseRun(void *opaque)
+{
+    virLXCFusePtr fuse = opaque;
+
+    if (fuse_loop(fuse->fuse) < 0)
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("fuse_loop failed"));
+
+    lxcFuseDestroy(fuse);
+}
+
+int lxcSetupFuse(virLXCFusePtr *f, virDomainDefPtr def)
+{
+    int ret = -1;
+    struct fuse_args args = FUSE_ARGS_INIT(0, NULL);
+    virLXCFusePtr fuse = NULL;
+
+    if (VIR_ALLOC(fuse) < 0)
+        goto cleanup;
+
+    fuse->def = def;
+
+    if (virMutexInit(&fuse->lock) < 0)
+        goto cleanup2;
+
+    if (virAsprintf(&fuse->mountpoint, "%s/%s/", LXC_STATE_DIR,
+                    def->name) < 0) {
+        virReportOOMError();
+        goto cleanup1;
+    }
+
+    if (virFileMakePath(fuse->mountpoint) < 0) {
+        virReportSystemError(errno, _("Cannot create %s"),
+                             fuse->mountpoint);
+        goto cleanup1;
+    }
+
+    /* process name is libvirt_lxc */
+    if (fuse_opt_add_arg(&args, "libvirt_lxc") == -1 ||
+        fuse_opt_add_arg(&args, "-odirect_io") == -1 ||
+        fuse_opt_add_arg(&args, "-ofsname=libvirt") == -1)
+        goto cleanup1;
+
+    fuse->ch = fuse_mount(fuse->mountpoint, &args);
+    if (fuse->ch == NULL)
+        goto cleanup1;
+
+    fuse->fuse = fuse_new(fuse->ch, &args, &lxcProcOper,
+                          sizeof(lxcProcOper), fuse->def);
+    if (fuse->fuse == NULL) {
+        fuse_unmount(fuse->mountpoint, fuse->ch);
+        goto cleanup1;
+    }
+
+    if (virThreadCreate(&fuse->thread, true, lxcFuseRun,
+                        (void *)fuse) < 0) {
+        lxcFuseDestroy(fuse);
+        goto cleanup1;
+    }
+
+    ret = 0;
+cleanup:
+    fuse_opt_free_args(&args);
+    *f = fuse;
+    return ret;
+cleanup1:
+    VIR_FREE(fuse->mountpoint);
+    virMutexDestroy(&fuse->lock);
+cleanup2:
+    VIR_FREE(fuse);
+    goto cleanup;
+}
+
+void lxcFreeFuse(virLXCFusePtr *f)
+{
+    virLXCFusePtr fuse = *f;
+    /* lxcFuseRun thread create success */
+    if (fuse) {
+        /* exit fuse_loop, lxcFuseRun thread may try to destroy
+         * fuse->fuse at the same time,so add a lock here. */
+        virMutexLock(&fuse->lock);
+        if (fuse->fuse)
+            fuse_exit(fuse->fuse);
+        virMutexUnlock(&fuse->lock);
+
+        virThreadJoin(&fuse->thread);
+
+        VIR_FREE(fuse->mountpoint);
+        VIR_FREE(*f);
+    }
+}
+#else
+int lxcSetupFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED,
+                  virDomainDefPtr def ATTRIBUTE_UNUSED)
+{
+    return 0;
+}
+
+void lxcFreeFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED)
+{
+}
+#endif

src/lxc/lxc_fuse.h

@@ -0,0 +1,51 @@
+/*
+ * 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"
+
+struct virLXCFuse {
+    virDomainDefPtr def;
+    virThread thread;
+    char *mountpoint;
+    struct fuse *fuse;
+    struct fuse_chan *ch;
+    virMutex lock;
+};
+typedef struct virLXCFuse *virLXCFusePtr;
+
+extern int lxcSetupFuse(virLXCFusePtr *f, virDomainDefPtr def);
+extern void lxcFreeFuse(virLXCFusePtr *f);
+
+#endif /* LXC_FUSE_H */

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"