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libvirt/src/lxc/lxc_fuse.c
Daniel P. Berrangé 5bff668dfb src: improve thread naming with human targetted names 
Historically threads are given a name based on the C function,
and this name is just used inside libvirt. With OS level thread
naming this name is now visible to debuggers, but also has to
fit in 15 characters on Linux, so function names are too long
in some cases.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2020-03-05 12:23:04 +00:00

379 lines
12 KiB
C
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/*
* Copyright (C) 2014 Red Hat, Inc.
* Copyright (C) 2012 Fujitsu Limited.
*
* lxc_fuse.c: fuse filesystem support for libvirt lxc
*
* 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 <sys/mount.h>
#include <mntent.h>
#include <unistd.h>
#include "lxc_fuse.h"
#include "lxc_cgroup.h"
#include "virerror.h"
#include "virfile.h"
#include "virbuffer.h"
#include "virstring.h"
#include "viralloc.h"
#include "virutil.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)
{
g_autofree 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));
mempath = g_strdup_printf("/proc/%s", path);
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)
return -errno;
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 {
return -ENOENT;
}
return 0;
}
static int lxcProcReaddir(const char *path, void *buf,
fuse_fill_dir_t filler,
off_t offset G_GNUC_UNUSED,
struct fuse_file_info *fi G_GNUC_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 G_GNUC_UNUSED,
struct fuse_file_info *fi G_GNUC_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;
g_autofree 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);
}
}
res = strlen(virBufferCurrentContent(new_meminfo));
if (res > size)
res = size;
memcpy(buf, virBufferCurrentContent(new_meminfo), res);
cleanup:
virBufferFreeAndReset(new_meminfo);
VIR_FORCE_FCLOSE(fd);
return res;
}
static int lxcProcRead(const char *path G_GNUC_UNUSED,
char *buf G_GNUC_UNUSED,
size_t size G_GNUC_UNUSED,
off_t offset G_GNUC_UNUSED,
struct fuse_file_info *fi G_GNUC_UNUSED)
{
int res = -ENOENT;
g_autofree char *hostpath = NULL;
struct fuse_context *context = NULL;
virDomainDefPtr def = NULL;
hostpath = g_strdup_printf("/proc/%s", path);
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);
}
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;
fuse->mountpoint = g_strdup_printf("%s/%s.fuse/", LXC_STATE_DIR, def->name);
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 (virThreadCreateFull(&fuse->thread, false, lxcFuseRun,
"lxc-fuse", false, (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 G_GNUC_UNUSED,
virDomainDefPtr def G_GNUC_UNUSED)
{
return 0;
}
int lxcStartFuse(virLXCFusePtr f G_GNUC_UNUSED)
{
return 0;
}
void lxcFreeFuse(virLXCFusePtr *f G_GNUC_UNUSED)
{
}
#endif
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