This patch is sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html
It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <[email protected]> Signed-off-by: Serge E. Hallyn <[email protected]> Cc: Eric W. Biederman <[email protected]> Cc: Paul Menage <[email protected]> Reviewed-by: Li Zefan <[email protected]> --- Documentation/cgroups/cgroups.txt | 14 +++++++++++- include/linux/cgroup.h | 4 +++ kernel/cgroup.c | 39 +++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+), 2 deletions(-) diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index b34823f..190018b 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -18,7 +18,8 @@ CONTENTS: 1.2 Why are cgroups needed ? 1.3 How are cgroups implemented ? 1.4 What does notify_on_release do ? - 1.5 How do I use cgroups ? + 1.5 What does clone_children do ? + 1.6 How do I use cgroups ? 2. Usage Examples and Syntax 2.1 Basic Usage 2.2 Attaching processes @@ -293,7 +294,16 @@ notify_on_release in the root cgroup at system boot is disabled value of their parents notify_on_release setting. The default value of a cgroup hierarchy's release_agent path is empty. -1.5 How do I use cgroups ? +1.5 What does clone_children do ? +--------------------------------- + +If the clone_children flag is enabled (1) in a cgroup, then all +cgroups created beneath will call the post_clone callbacks for each +subsystem of the newly created cgroup. Usually when this callback is +implemented for a subsystem, it copies the values of the parent +subsystem, this is the case for the cpuset. + +1.6 How do I use cgroups ? -------------------------- To start a new job that is to be contained within a cgroup, using diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 3cb7d04..d01543b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -154,6 +154,10 @@ enum { * A thread in rmdir() is wating for this cgroup. */ CGRP_WAIT_ON_RMDIR, + /* + * Clone cgroup values when creating a new child cgroup + */ + CGRP_CLONE_CHILDREN, }; /* which pidlist file are we talking about? */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index e5c5497..0473a9a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -229,6 +229,7 @@ inline int cgroup_is_removed(const struct cgroup *cgrp) /* bits in struct cgroupfs_root flags field */ enum { ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ + ROOT_CLONE_CHILDREN, /* mounted subsystems will inherit from parent */ }; static int cgroup_is_releasable(const struct cgroup *cgrp) @@ -244,6 +245,11 @@ static int notify_on_release(const struct cgroup *cgrp) return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); } +static int clone_children(const struct cgroup *cgrp) +{ + return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); +} + /* * for_each_subsys() allows you to iterate on each subsystem attached to * an active hierarchy @@ -1038,6 +1044,8 @@ static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) seq_printf(seq, ",%s", ss->name); if (test_bit(ROOT_NOPREFIX, &root->flags)) seq_puts(seq, ",noprefix"); + if (test_bit(ROOT_CLONE_CHILDREN, &root->flags)) + seq_puts(seq, ",clone_children"); if (strlen(root->release_agent_path)) seq_printf(seq, ",release_agent=%s", root->release_agent_path); if (strlen(root->name)) @@ -1097,6 +1105,8 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) opts->none = true; } else if (!strcmp(token, "noprefix")) { set_bit(ROOT_NOPREFIX, &opts->flags); + } else if (!strcmp(token, "clone_children")) { + set_bit(ROOT_CLONE_CHILDREN, &opts->flags); } else if (!strncmp(token, "release_agent=", 14)) { /* Specifying two release agents is forbidden */ if (opts->release_agent) @@ -1357,6 +1367,8 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) strcpy(root->release_agent_path, opts->release_agent); if (opts->name) strcpy(root->name, opts->name); + if (test_bit(ROOT_CLONE_CHILDREN, &opts->flags)) + set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); return root; } @@ -3175,6 +3187,23 @@ fail: return ret; } +static u64 cgroup_clone_children_read(struct cgroup *cgrp, + struct cftype *cft) +{ + return clone_children(cgrp); +} + +static int cgroup_clone_children_write(struct cgroup *cgrp, + struct cftype *cft, + u64 val) +{ + if (val) + set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + else + clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + return 0; +} + /* * for the common functions, 'private' gives the type of file */ @@ -3205,6 +3234,11 @@ static struct cftype files[] = { .write_string = cgroup_write_event_control, .mode = S_IWUGO, }, + { + .name = "cgroup.clone_children", + .read_u64 = cgroup_clone_children_read, + .write_u64 = cgroup_clone_children_write, + }, }; static struct cftype cft_release_agent = { @@ -3334,6 +3368,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (notify_on_release(parent)) set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); + if (clone_children(parent)) + set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + for_each_subsys(root, ss) { struct cgroup_subsys_state *css = ss->create(ss, cgrp); @@ -3348,6 +3385,8 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, goto err_destroy; } /* At error, ->destroy() callback has to free assigned ID. */ + if (clone_children(parent) && ss->post_clone) + ss->post_clone(ss, cgrp); } cgroup_lock_hierarchy(root); -- 1.7.0.4 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
