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Re: [libvirt] [PATCH v5 2/6] add fuse support for libvirt lxc



On Thu, Oct 25, 2012 at 06:38:23PM +0800, Gao feng wrote:
> 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 Lxc-containename-fuse,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       |  172 ++++++++++++++++++++++++++++++++++++++++++++++
>  src/lxc/lxc_fuse.h       |   40 +++++++++++
>  src/lxc/lxc_process.c    |    1 +
>  8 files changed, 251 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 187663f..e7b2bd6 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)
> @@ -1672,6 +1675,7 @@ libvirt_lxc_SOURCES =						\
>  libvirt_lxc_LDFLAGS = $(WARN_CFLAGS) $(AM_LDFLAGS)
>  libvirt_lxc_LDADD =			\
>  		$(NUMACTL_LIBS) \
> +		$(FUSE_LIBS) \
>  		libvirt-net-rpc-server.la \
>  		libvirt-net-rpc.la \
>  		libvirt_security_manager.la \
> @@ -1690,7 +1694,8 @@ endif
>  libvirt_lxc_CFLAGS =				\
>  		-I$(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..9c0a10c 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(ctrl->def))
> +            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..f7615a2
> --- /dev/null
> +++ b/src/lxc/lxc_fuse.c
> @@ -0,0 +1,172 @@
> +/*
> + * 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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#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;
> +    char *name = NULL;
> +    virDomainDefPtr DomainDef = (virDomainDefPtr) opaque;

It is common practice to just use 'def' as the variable names in
this scenario. Also there is never any need to cast from a 'void *'
pointer in C (as opposed to C++ which does require casts).

> +
> +    if (virAsprintf(&name, "Lxc-%s-fuse", DomainDef->name) < 0) {
> +        virReportOOMError();
> +        goto cleanup;
> +    }

I wonder if we should just simplify this and use the fixed
name 'libvirt'. Since these mounts are only visible inside
the container, I don't think there's a huge need for customized
unique names.

> +
> +    if (virAsprintf(&path, "%s/%s/", LXC_STATE_DIR, DomainDef->name) < 0) {
> +        virReportOOMError();
> +        goto cleanup;
> +    }
> +
> +    if (virFileMakePath(path) < 0) {
> +        virReportSystemError(errno, _("Cannot create %s"), path);
> +        goto cleanup;
> +    }
> +
> +    argv[0] = name;
> +    argv[1] = path;
> +    argv[2] = (char *)"-odirect_io";
> +    argv[3] = (char *)"-f";
> +
> +    if (fuse_main(argc, argv, &lxcProcOper, DomainDef) < 0)
> +        virReportSystemError(errno, "%s", _("Cannot start fuse"));
> +
> +cleanup:
> +    VIR_FREE(name);
> +    VIR_FREE(path);
> +    return;
> +}
> +
> +int lxcRegisterFuseSuccess(virDomainDefPtr def)
> +{
> +    FILE *procmnt = NULL;
> +    struct mntent mntent;
> +    char mntbuf[1024];
> +    char *name = NULL;
> +    int ret = 0;
> +
> +    if (!(procmnt = setmntent("/proc/mounts", "r"))) {
> +        virReportSystemError(errno, "%s",
> +                             _("Failed to read /proc/mounts"));
> +        return ret;
> +    }
> +
> +    if (virAsprintf(&name, "Lxc-%s-fuse", def->name) < 0) {
> +        virReportOOMError();
> +        goto cleanup;
> +    }

Likewise here just called it 'libvirt' 

> +
> +    while (getmntent_r(procmnt, &mntent, mntbuf, sizeof(mntbuf)) != NULL) {
> +        VIR_DEBUG("Got %s == %s ?\n",mntent.mnt_fsname, name);
> +        if (STRNEQ(mntent.mnt_fsname, name))
> +            continue;
> +
> +        ret = 1;
> +        break;
> +    }
> +
> +cleanup:
> +    endmntent(procmnt);
> +    VIR_FREE(name);
> +    return ret;
> +}
> +
> +#else
> +void lxcRegisterFuse(void *opaque ATTRIBUTE_UNUSED)
> +{
> +}
> +
> +int lxcRegisterFuseSuccess(virDomainDefPtr def ATTRIBUTE_UNUSED)
> +{
> +    return 1;
> +}
> +#endif
> diff --git a/src/lxc/lxc_fuse.h b/src/lxc/lxc_fuse.h
> new file mode 100644
> index 0000000..1937ad8
> --- /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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> + */
> +
> +#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"


make syntax-check ought to complain about bogus indentation
here in all these macros.

> +
> +extern void lxcRegisterFuse(void *opaque);
> +extern int lxcRegisterFuseSuccess(virDomainDefPtr def);
> +#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"

ACK with the minor chanes described


Daniel
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