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lxcfs: introduce new option --enable-cgroup
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During our private discussion, Stéphane proposed
to add a new option --enable-cgroup to explicitly
enable old cgroup emulation code

It's worth mentioning that cgroup code in LXCFS
is not widely used, because it was written before
cgroup namespace era and not actual these days.

Signed-off-by: Alexander Mikhalitsyn <[email protected]>
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@mihalicyn
mihalicyn committed Mar 15, 2024
1 parent ce8e6e9 commit 000b539
Showing 1 changed file with 19 additions and 13 deletions.
32 changes: 19 additions & 13 deletions src/lxcfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -661,6 +661,8 @@ static int do_sys_releasedir(const char *path, struct fuse_file_info *fi)
return __sys_releasedir(path, fi);
}

static bool cgroup_is_enabled = false;

#if HAVE_FUSE3
static int lxcfs_getattr(const char *path, struct stat *sb, struct fuse_file_info *fi)
#else
Expand All @@ -681,7 +683,7 @@ static int lxcfs_getattr(const char *path, struct stat *sb)
return 0;
}

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_getattr(path, sb);
down_users();
Expand Down Expand Up @@ -712,7 +714,7 @@ static int lxcfs_opendir(const char *path, struct fuse_file_info *fi)
if (strcmp(path, "/") == 0)
return 0;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_opendir(path, fi);
down_users();
Expand Down Expand Up @@ -747,13 +749,13 @@ static int lxcfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
dir_filler(filler, buf, "..", 0) != 0 ||
dir_filler(filler, buf, "proc", 0) != 0 ||
dir_filler(filler, buf, "sys", 0) != 0 ||
dir_filler(filler, buf, "cgroup", 0) != 0)
(cgroup_is_enabled && dir_filler(filler, buf, "cgroup", 0) != 0))
return -ENOMEM;

return 0;
}

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_readdir(path, buf, filler, offset, fi);
down_users();
Expand Down Expand Up @@ -784,7 +786,7 @@ static int lxcfs_access(const char *path, int mode)
if (strcmp(path, "/") == 0 && (mode & W_OK) == 0)
return 0;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_access(path, mode);
down_users();
Expand Down Expand Up @@ -846,7 +848,7 @@ static int lxcfs_open(const char *path, struct fuse_file_info *fi)
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_open(path, fi);
down_users();
Expand Down Expand Up @@ -875,7 +877,7 @@ static int lxcfs_read(const char *path, char *buf, size_t size, off_t offset,
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_read(path, buf, size, offset, fi);
down_users();
Expand Down Expand Up @@ -904,7 +906,7 @@ int lxcfs_write(const char *path, const char *buf, size_t size, off_t offset,
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_write(path, buf, size, offset, fi);
down_users();
Expand Down Expand Up @@ -983,7 +985,7 @@ int lxcfs_mkdir(const char *path, mode_t mode)
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_mkdir(path, mode);
down_users();
Expand All @@ -1001,7 +1003,7 @@ int lxcfs_chown(const char *path, uid_t uid, gid_t gid)
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_chown(path, uid, gid);
down_users();
Expand All @@ -1028,7 +1030,7 @@ int lxcfs_truncate(const char *path, off_t newsize, struct fuse_file_info *fi)
int lxcfs_truncate(const char *path, off_t newsize)
#endif
{
if (strncmp(path, "/cgroup", 7) == 0)
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0)
return 0;

if (strncmp(path, "/sys", 4) == 0)
Expand All @@ -1041,7 +1043,7 @@ int lxcfs_rmdir(const char *path)
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_rmdir(path);
down_users();
Expand All @@ -1059,7 +1061,7 @@ int lxcfs_chmod(const char *path, mode_t mode)
{
int ret;

if (strncmp(path, "/cgroup", 7) == 0) {
if (cgroup_is_enabled && strncmp(path, "/cgroup", 7) == 0) {
up_users();
ret = do_cg_chmod(path, mode);
down_users();
Expand Down Expand Up @@ -1190,6 +1192,7 @@ static void usage(void)
lxcfs_info(" -v, --version Print lxcfs version");
lxcfs_info(" --enable-cfs Enable CPU virtualization via CPU shares");
lxcfs_info(" --enable-pidfd Use pidfd for process tracking");
lxcfs_info(" --enable-cgroup Enable cgroup emulation code");
exit(EXIT_FAILURE);
}

Expand Down Expand Up @@ -1238,6 +1241,7 @@ static const struct option long_options[] = {

{"enable-cfs", no_argument, 0, 0 },
{"enable-pidfd", no_argument, 0, 0 },
{"enable-cgroup", no_argument, 0, 0 },

{"pidfile", required_argument, 0, 'p' },
{ },
Expand Down Expand Up @@ -1318,6 +1322,8 @@ int main(int argc, char *argv[])
opts->use_pidfd = true;
else if (strcmp(long_options[idx].name, "enable-cfs") == 0)
opts->use_cfs = true;
else if (strcmp(long_options[idx].name, "enable-cgroup") == 0)
cgroup_is_enabled = true;
else
usage();
break;
Expand Down

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