libvirt/src/lxc/lxc_fuse.c

399 lines
12 KiB
C

/*
* Copyright (C) 2014 Red Hat, Inc.
* 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 "lxc_cgroup.h"
#include "virerror.h"
#include "virfile.h"
#include "virbuffer.h"
#include "virstring.h"
#define VIR_FROM_THIS VIR_FROM_LXC
#if WITH_FUSE
static const char *fuse_meminfo_path = "/meminfo";
static int lxcProcGetattr(const char *path, struct stat *stbuf)
{
int res;
char *mempath = NULL;
struct stat sb;
struct fuse_context *context = fuse_get_context();
virDomainDefPtr def = (virDomainDefPtr)context->private_data;
memset(stbuf, 0, sizeof(struct stat));
if (virAsprintf(&mempath, "/proc/%s", path) < 0)
return -errno;
res = 0;
if (STREQ(path, "/")) {
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
} else if (STREQ(path, fuse_meminfo_path)) {
if (stat(mempath, &sb) < 0) {
res = -errno;
goto cleanup;
}
stbuf->st_uid = def->idmap.uidmap ? def->idmap.uidmap[0].target : 0;
stbuf->st_gid = def->idmap.gidmap ? def->idmap.gidmap[0].target : 0;
stbuf->st_mode = sb.st_mode;
stbuf->st_nlink = 1;
stbuf->st_blksize = sb.st_blksize;
stbuf->st_blocks = sb.st_blocks;
stbuf->st_size = sb.st_size;
stbuf->st_atime = sb.st_atime;
stbuf->st_ctime = sb.st_ctime;
stbuf->st_mtime = sb.st_mtime;
} else {
res = -ENOENT;
}
cleanup:
VIR_FREE(mempath);
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 (STRNEQ(path, "/"))
return -ENOENT;
filler(buf, ".", NULL, 0);
filler(buf, "..", NULL, 0);
filler(buf, fuse_meminfo_path + 1, NULL, 0);
return 0;
}
static int lxcProcOpen(const char *path ATTRIBUTE_UNUSED,
struct fuse_file_info *fi ATTRIBUTE_UNUSED)
{
if (STRNEQ(path, fuse_meminfo_path))
return -ENOENT;
if ((fi->flags & 3) != O_RDONLY)
return -EACCES;
return 0;
}
static int lxcProcHostRead(char *path, char *buf, size_t size, off_t offset)
{
int fd;
int res;
fd = open(path, O_RDONLY);
if (fd == -1)
return -errno;
if ((res = pread(fd, buf, size, offset)) < 0)
res = -errno;
VIR_FORCE_CLOSE(fd);
return res;
}
static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
char *buf, size_t size, off_t offset)
{
int res;
FILE *fd = NULL;
char *line = NULL;
size_t n;
struct virLXCMeminfo meminfo;
virBuffer buffer = VIR_BUFFER_INITIALIZER;
virBufferPtr new_meminfo = &buffer;
if (virLXCCgroupGetMeminfo(&meminfo) < 0) {
virErrorSetErrnoFromLastError();
return -errno;
}
fd = fopen(hostpath, "r");
if (fd == NULL) {
virReportSystemError(errno, _("Cannot open %s"), hostpath);
res = -errno;
goto cleanup;
}
if (fseek(fd, offset, SEEK_SET) < 0) {
virReportSystemError(errno, "%s", _("fseek failed"));
res = -errno;
goto cleanup;
}
res = -1;
while (getline(&line, &n, fd) > 0) {
char *ptr = strchr(line, ':');
if (!ptr)
continue;
*ptr = '\0';
if (STREQ(line, "MemTotal") &&
(virMemoryLimitIsSet(def->mem.hard_limit) ||
virDomainDefGetMemoryTotal(def))) {
virBufferAsprintf(new_meminfo, "MemTotal: %8llu kB\n",
meminfo.memtotal);
} else if (STREQ(line, "MemFree") &&
(virMemoryLimitIsSet(def->mem.hard_limit) ||
virDomainDefGetMemoryTotal(def))) {
virBufferAsprintf(new_meminfo, "MemFree: %8llu kB\n",
(meminfo.memtotal - meminfo.memusage));
} else if (STREQ(line, "MemAvailable") &&
(virMemoryLimitIsSet(def->mem.hard_limit) ||
virDomainDefGetMemoryTotal(def))) {
/* MemAvailable is actually MemFree + SRReclaimable +
some other bits, but MemFree is the closest approximation
we have */
virBufferAsprintf(new_meminfo, "MemAvailable: %8llu kB\n",
(meminfo.memtotal - meminfo.memusage));
} else if (STREQ(line, "Buffers")) {
virBufferAsprintf(new_meminfo, "Buffers: %8d kB\n", 0);
} else if (STREQ(line, "Cached")) {
virBufferAsprintf(new_meminfo, "Cached: %8llu kB\n",
meminfo.cached);
} else if (STREQ(line, "Active")) {
virBufferAsprintf(new_meminfo, "Active: %8llu kB\n",
(meminfo.active_anon + meminfo.active_file));
} else if (STREQ(line, "Inactive")) {
virBufferAsprintf(new_meminfo, "Inactive: %8llu kB\n",
(meminfo.inactive_anon + meminfo.inactive_file));
} else if (STREQ(line, "Active(anon)")) {
virBufferAsprintf(new_meminfo, "Active(anon): %8llu kB\n",
meminfo.active_anon);
} else if (STREQ(line, "Inactive(anon)")) {
virBufferAsprintf(new_meminfo, "Inactive(anon): %8llu kB\n",
meminfo.inactive_anon);
} else if (STREQ(line, "Active(file)")) {
virBufferAsprintf(new_meminfo, "Active(file): %8llu kB\n",
meminfo.active_file);
} else if (STREQ(line, "Inactive(file)")) {
virBufferAsprintf(new_meminfo, "Inactive(file): %8llu kB\n",
meminfo.inactive_file);
} else if (STREQ(line, "Unevictable")) {
virBufferAsprintf(new_meminfo, "Unevictable: %8llu kB\n",
meminfo.unevictable);
} else if (STREQ(line, "SwapTotal") &&
virMemoryLimitIsSet(def->mem.swap_hard_limit)) {
virBufferAsprintf(new_meminfo, "SwapTotal: %8llu kB\n",
(meminfo.swaptotal - meminfo.memtotal));
} else if (STREQ(line, "SwapFree") &&
virMemoryLimitIsSet(def->mem.swap_hard_limit)) {
virBufferAsprintf(new_meminfo, "SwapFree: %8llu kB\n",
(meminfo.swaptotal - meminfo.memtotal -
meminfo.swapusage + meminfo.memusage));
} else if (STREQ(line, "Slab")) {
virBufferAsprintf(new_meminfo, "Slab: %8d kB\n", 0);
} else if (STREQ(line, "SReclaimable")) {
virBufferAsprintf(new_meminfo, "SReclaimable: %8d kB\n", 0);
} else if (STREQ(line, "SUnreclaim")) {
virBufferAsprintf(new_meminfo, "SUnreclaim: %8d kB\n", 0);
} else {
*ptr = ':';
virBufferAdd(new_meminfo, line, -1);
}
if (virBufferCheckError(new_meminfo) < 0) {
res = -errno;
goto cleanup;
}
}
res = strlen(virBufferCurrentContent(new_meminfo));
if (res > size)
res = size;
memcpy(buf, virBufferCurrentContent(new_meminfo), res);
cleanup:
VIR_FREE(line);
virBufferFreeAndReset(new_meminfo);
VIR_FORCE_FCLOSE(fd);
return res;
}
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)
{
int res = -ENOENT;
char *hostpath = NULL;
struct fuse_context *context = NULL;
virDomainDefPtr def = NULL;
if (virAsprintf(&hostpath, "/proc/%s", path) < 0)
return -errno;
context = fuse_get_context();
def = (virDomainDefPtr)context->private_data;
if (STREQ(path, fuse_meminfo_path)) {
if ((res = lxcProcReadMeminfo(hostpath, def, buf, size, offset)) < 0)
res = lxcProcHostRead(hostpath, buf, size, offset);
}
VIR_FREE(hostpath);
return res;
}
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.fuse/", LXC_STATE_DIR,
def->name) < 0)
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, "-oallow_other") == -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;
}
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;
}
int lxcStartFuse(virLXCFusePtr fuse)
{
if (virThreadCreate(&fuse->thread, false, lxcFuseRun,
(void *)fuse) < 0) {
lxcFuseDestroy(fuse);
return -1;
}
return 0;
}
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);
VIR_FREE(fuse->mountpoint);
VIR_FREE(*f);
}
}
#else
int lxcSetupFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED,
virDomainDefPtr def ATTRIBUTE_UNUSED)
{
return 0;
}
int lxcStartFuse(virLXCFusePtr f ATTRIBUTE_UNUSED)
{
return 0;
}
void lxcFreeFuse(virLXCFusePtr *f ATTRIBUTE_UNUSED)
{
}
#endif