From d3c92fb53bb92ec00914aa4b51bd21d88e887128 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 23 Nov 2016 12:27:32 -0500 Subject: [PATCH] core: keep supporting cgroup hybrid layout from v232 for live upgrades v232's cgroup hybrid mode mounted v2 on /sys/fs/cgroup/elogind, which unfortunately broke other tools which expect v1 there. From v233 on, hybrid mode instead mounts and uses v2 on /sys/fs/cgroup/unified and keeps /sys/fs/cgroup/elogind on v1 for compatibility with external tools. However, to keep elogind live upgrades working, v233+ should be able to recognize v232 layout and keep using it. This patch adds v232 hybrid mode support. If v232 layout is detected, cg_unified(SYSTEMD_CGRouP_CONTROLLER) keeps returning %true but cg_hybrid_unified() returns %false. This keeps process management on cgroup v2 but turns off the parallel layout. --- src/basic/cgroup-util.c | 110 ++++++++++++++++++++++++++++++++++------ 1 file changed, 94 insertions(+), 16 deletions(-) diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c index 272fb1973..1c26c7f8f 100644 --- a/src/basic/cgroup-util.c +++ b/src/basic/cgroup-util.c @@ -210,6 +210,12 @@ int cg_rmdir(const char *controller, const char *path) { if (r < 0 && errno != ENOENT) return -errno; + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + r = cg_rmdir(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path); + if (r < 0) + log_warning_errno(r, "Failed to remove compat systemd cgroup %s: %m", path); + } + return 0; } @@ -548,8 +554,12 @@ static const char *controller_to_dirname(const char *controller) { * just cuts off the name= prefixed used for named * hierarchies, if it is specified. */ - if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) - controller = SYSTEMD_CGROUP_CONTROLLER_LEGACY; + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) { + if (cg_hybrid_unified()) + controller = SYSTEMD_CGROUP_CONTROLLER_HYBRID; + else + controller = SYSTEMD_CGROUP_CONTROLLER_LEGACY; + } e = startswith(controller, "name="); if (e) @@ -709,7 +719,7 @@ static int trim_cb(const char *path, const struct stat *sb, int typeflag, struct int cg_trim(const char *controller, const char *path, bool delete_root) { _cleanup_free_ char *fs = NULL; - int r = 0; + int r = 0, q; assert(path); @@ -732,6 +742,12 @@ int cg_trim(const char *controller, const char *path, bool delete_root) { return -errno; } + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + q = cg_trim(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, delete_root); + if (q < 0) + log_warning_errno(q, "Failed to trim compat systemd cgroup %s: %m", path); + } + return r; } @@ -755,6 +771,12 @@ int cg_create(const char *controller, const char *path) { return -errno; } + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + r = cg_create(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path); + if (r < 0) + log_warning_errno(r, "Failed to create compat systemd cgroup %s: %m", path); + } + return 1; } @@ -792,7 +814,17 @@ int cg_attach(const char *controller, const char *path, pid_t pid) { xsprintf(c, PID_FMT "\n", pid); - return write_string_file(fs, c, 0); + r = write_string_file(fs, c, 0); + if (r < 0) + return r; + + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + r = cg_attach(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, pid); + if (r < 0) + log_warning_errno(r, "Failed to attach %d to compat systemd cgroup %s: %m", pid, path); + } + + return 0; } int cg_attach_fallback(const char *controller, const char *path, pid_t pid) { @@ -842,7 +874,17 @@ int cg_set_group_access( if (r < 0) return r; - return chmod_and_chown(fs, mode, uid, gid); + r = chmod_and_chown(fs, mode, uid, gid); + if (r < 0) + return r; + + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + r = cg_set_group_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid); + if (r < 0) + log_warning_errno(r, "Failed to set group access on compat systemd cgroup %s: %m", path); + } + + return 0; } int cg_set_task_access( @@ -871,13 +913,18 @@ int cg_set_task_access( if (r < 0) return r; - if (cg_unified(controller)) - return 0; + if (!cg_unified(controller)) { + /* Compatibility, Always keep values for "tasks" in sync with + * "cgroup.procs" */ + if (cg_get_path(controller, path, "tasks", &procs) >= 0) + (void) chmod_and_chown(procs, mode, uid, gid); + } - /* Compatibility, Always keep values for "tasks" in sync with - * "cgroup.procs" */ - if (cg_get_path(controller, path, "tasks", &procs) >= 0) - (void) chmod_and_chown(procs, mode, uid, gid); + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER) && cg_hybrid_unified()) { + r = cg_set_task_access(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, mode, uid, gid); + if (r < 0) + log_warning_errno(r, "Failed to set task access on compat systemd cgroup %s: %m", path); + } return 0; } @@ -2292,6 +2339,20 @@ int cg_kernel_controllers(Set *controllers) { static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN; +/* The hybrid mode was initially implemented in v232 and simply mounted + * cgroup v2 on /sys/fs/cgroup/systemd. This unfortunately broke other + * tools (such as docker) which expected the v1 "name=systemd" hierarchy + * on /sys/fs/cgroup/systemd. From v233 and on, the hybrid mode mountnbs + * v2 on /sys/fs/cgroup/unified and maintains "name=systemd" hierarchy + * on /sys/fs/cgroup/systemd for compatibility with other tools. + * + * To keep live upgrade working, we detect and support v232 layout. When + * v232 layout is detected, to keep cgroup v2 process management but + * disable the compat dual layout, we return %true on + * cg_unified(SYSTEMD_CGROUP_CONTROLLER) and %false on cg_hybrid_unified(). + */ +static thread_local bool unified_systemd_v232; + static int cg_update_unified(void) { struct statfs fs; @@ -2311,11 +2372,21 @@ static int cg_update_unified(void) { if (F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) unified_cache = CGROUP_UNIFIED_ALL; else if (F_TYPE_EQUAL(fs.f_type, TMPFS_MAGIC)) { - if (statfs("/sys/fs/cgroup/systemd/", &fs) < 0) - return -errno; - - unified_cache = F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC) ? - CGROUP_UNIFIED_SYSTEMD : CGROUP_UNIFIED_NONE; + if (statfs("/sys/fs/cgroup/unified/", &fs) == 0 && + F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) { + unified_cache = CGROUP_UNIFIED_SYSTEMD; + unified_systemd_v232 = false; + } else if (statfs("/sys/fs/cgroup/systemd/", &fs) == 0 && + F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) { + unified_cache = CGROUP_UNIFIED_SYSTEMD; + unified_systemd_v232 = true; + } else { + if (statfs("/sys/fs/cgroup/systemd/", &fs) < 0) + return -errno; + if (!F_TYPE_EQUAL(fs.f_type, CGROUP_SUPER_MAGIC)) + return -ENOMEDIUM; + unified_cache = CGROUP_UNIFIED_NONE; + } } else return -ENOMEDIUM; #else @@ -2346,6 +2417,13 @@ bool cg_all_unified(void) { } #if 0 /// UNNEEDED by elogind +bool cg_hybrid_unified(void) { + + assert(cg_update_unified() >= 0); + + return unified_cache == CGROUP_UNIFIED_SYSTEMD && !unified_systemd_v232; +} + int cg_unified_flush(void) { unified_cache = CGROUP_UNIFIED_UNKNOWN; -- 2.30.2