forked from Minki/linux
cgroups: support named cgroups hierarchies
To simplify referring to cgroup hierarchies in mount statements, and to allow disambiguation in the presence of empty hierarchies and multiply-bindable subsystems this patch adds support for naming a new cgroup hierarchy via the "name=" mount option A pre-existing hierarchy may be specified by either name or by subsystems; a hierarchy's name cannot be changed by a remount operation. Example usage: # To create a hierarchy called "foo" containing the "cpu" subsystem mount -t cgroup -oname=foo,cpu cgroup /mnt/cgroup1 # To mount the "foo" hierarchy on a second location mount -t cgroup -oname=foo cgroup /mnt/cgroup2 Signed-off-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Menage
Linus Torvalds
parent
34f77a90f7
commit
c6d57f3312
@ -408,6 +408,26 @@ You can attach the current shell task by echoing 0:
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# echo 0 > tasks
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2.3 Mounting hierarchies by name
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--------------------------------
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Passing the name=<x> option when mounting a cgroups hierarchy
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associates the given name with the hierarchy. This can be used when
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mounting a pre-existing hierarchy, in order to refer to it by name
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rather than by its set of active subsystems. Each hierarchy is either
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nameless, or has a unique name.
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The name should match [\w.-]+
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When passing a name=<x> option for a new hierarchy, you need to
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specify subsystems manually; the legacy behaviour of mounting all
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subsystems when none are explicitly specified is not supported when
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you give a subsystem a name.
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The name of the subsystem appears as part of the hierarchy description
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in /proc/mounts and /proc/<pid>/cgroups.
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3. Kernel API
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=============
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186
kernel/cgroup.c
186
kernel/cgroup.c
@ -23,6 +23,7 @@
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*/
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#include <linux/cgroup.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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@ -60,6 +61,8 @@ static struct cgroup_subsys *subsys[] = {
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#include <linux/cgroup_subsys.h>
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};
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#define MAX_CGROUP_ROOT_NAMELEN 64
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/*
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* A cgroupfs_root represents the root of a cgroup hierarchy,
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* and may be associated with a superblock to form an active
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@ -94,6 +97,9 @@ struct cgroupfs_root {
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/* The path to use for release notifications. */
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char release_agent_path[PATH_MAX];
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/* The name for this hierarchy - may be empty */
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char name[MAX_CGROUP_ROOT_NAMELEN];
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};
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/*
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@ -841,6 +847,8 @@ static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs)
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seq_puts(seq, ",noprefix");
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if (strlen(root->release_agent_path))
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seq_printf(seq, ",release_agent=%s", root->release_agent_path);
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if (strlen(root->name))
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seq_printf(seq, ",name=%s", root->name);
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mutex_unlock(&cgroup_mutex);
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return 0;
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}
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@ -849,6 +857,9 @@ struct cgroup_sb_opts {
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unsigned long subsys_bits;
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unsigned long flags;
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char *release_agent;
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char *name;
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struct cgroupfs_root *new_root;
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};
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/* Convert a hierarchy specifier into a bitmask of subsystems and
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@ -863,9 +874,7 @@ static int parse_cgroupfs_options(char *data,
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mask = ~(1UL << cpuset_subsys_id);
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#endif
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opts->subsys_bits = 0;
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opts->flags = 0;
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opts->release_agent = NULL;
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memset(opts, 0, sizeof(*opts));
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while ((token = strsep(&o, ",")) != NULL) {
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if (!*token)
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@ -885,11 +894,33 @@ static int parse_cgroupfs_options(char *data,
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/* Specifying two release agents is forbidden */
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if (opts->release_agent)
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return -EINVAL;
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opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL);
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opts->release_agent =
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kstrndup(token + 14, PATH_MAX, GFP_KERNEL);
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if (!opts->release_agent)
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return -ENOMEM;
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strncpy(opts->release_agent, token + 14, PATH_MAX - 1);
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opts->release_agent[PATH_MAX - 1] = 0;
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} else if (!strncmp(token, "name=", 5)) {
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int i;
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const char *name = token + 5;
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/* Can't specify an empty name */
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if (!strlen(name))
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return -EINVAL;
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/* Must match [\w.-]+ */
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for (i = 0; i < strlen(name); i++) {
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char c = name[i];
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if (isalnum(c))
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continue;
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if ((c == '.') || (c == '-') || (c == '_'))
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continue;
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return -EINVAL;
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}
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/* Specifying two names is forbidden */
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if (opts->name)
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return -EINVAL;
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opts->name = kstrndup(name,
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MAX_CGROUP_ROOT_NAMELEN,
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GFP_KERNEL);
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if (!opts->name)
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return -ENOMEM;
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} else {
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struct cgroup_subsys *ss;
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int i;
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@ -916,7 +947,7 @@ static int parse_cgroupfs_options(char *data,
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return -EINVAL;
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/* We can't have an empty hierarchy */
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if (!opts->subsys_bits)
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if (!opts->subsys_bits && !opts->name)
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return -EINVAL;
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return 0;
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@ -944,6 +975,12 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
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goto out_unlock;
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}
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/* Don't allow name to change at remount */
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if (opts.name && strcmp(opts.name, root->name)) {
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ret = -EINVAL;
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goto out_unlock;
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}
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ret = rebind_subsystems(root, opts.subsys_bits);
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if (ret)
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goto out_unlock;
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@ -955,6 +992,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data)
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strcpy(root->release_agent_path, opts.release_agent);
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out_unlock:
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kfree(opts.release_agent);
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kfree(opts.name);
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
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unlock_kernel();
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@ -977,6 +1015,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
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INIT_LIST_HEAD(&cgrp->pids_list);
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init_rwsem(&cgrp->pids_mutex);
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}
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static void init_cgroup_root(struct cgroupfs_root *root)
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{
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struct cgroup *cgrp = &root->top_cgroup;
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@ -990,31 +1029,59 @@ static void init_cgroup_root(struct cgroupfs_root *root)
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static int cgroup_test_super(struct super_block *sb, void *data)
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{
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struct cgroupfs_root *new = data;
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struct cgroup_sb_opts *opts = data;
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struct cgroupfs_root *root = sb->s_fs_info;
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/* First check subsystems */
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if (new->subsys_bits != root->subsys_bits)
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return 0;
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/* If we asked for a name then it must match */
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if (opts->name && strcmp(opts->name, root->name))
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return 0;
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/* Next check flags */
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if (new->flags != root->flags)
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/* If we asked for subsystems then they must match */
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if (opts->subsys_bits && (opts->subsys_bits != root->subsys_bits))
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return 0;
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return 1;
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}
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static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
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{
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struct cgroupfs_root *root;
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/* Empty hierarchies aren't supported */
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if (!opts->subsys_bits)
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return NULL;
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root = kzalloc(sizeof(*root), GFP_KERNEL);
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if (!root)
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return ERR_PTR(-ENOMEM);
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init_cgroup_root(root);
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root->subsys_bits = opts->subsys_bits;
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root->flags = opts->flags;
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if (opts->release_agent)
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strcpy(root->release_agent_path, opts->release_agent);
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if (opts->name)
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strcpy(root->name, opts->name);
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return root;
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}
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static int cgroup_set_super(struct super_block *sb, void *data)
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{
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int ret;
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struct cgroupfs_root *root = data;
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struct cgroup_sb_opts *opts = data;
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/* If we don't have a new root, we can't set up a new sb */
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if (!opts->new_root)
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return -EINVAL;
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BUG_ON(!opts->subsys_bits);
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ret = set_anon_super(sb, NULL);
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if (ret)
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return ret;
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sb->s_fs_info = root;
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root->sb = sb;
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sb->s_fs_info = opts->new_root;
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opts->new_root->sb = sb;
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sb->s_blocksize = PAGE_CACHE_SIZE;
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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@ -1051,48 +1118,43 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
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void *data, struct vfsmount *mnt)
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{
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struct cgroup_sb_opts opts;
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struct cgroupfs_root *root;
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int ret = 0;
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struct super_block *sb;
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struct cgroupfs_root *root;
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struct list_head tmp_cg_links;
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struct cgroupfs_root *new_root;
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/* First find the desired set of subsystems */
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ret = parse_cgroupfs_options(data, &opts);
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if (ret) {
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kfree(opts.release_agent);
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return ret;
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if (ret)
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goto out_err;
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/*
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* Allocate a new cgroup root. We may not need it if we're
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* reusing an existing hierarchy.
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*/
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new_root = cgroup_root_from_opts(&opts);
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if (IS_ERR(new_root)) {
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ret = PTR_ERR(new_root);
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goto out_err;
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}
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opts.new_root = new_root;
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root = kzalloc(sizeof(*root), GFP_KERNEL);
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if (!root) {
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kfree(opts.release_agent);
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return -ENOMEM;
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}
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init_cgroup_root(root);
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root->subsys_bits = opts.subsys_bits;
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root->flags = opts.flags;
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if (opts.release_agent) {
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strcpy(root->release_agent_path, opts.release_agent);
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kfree(opts.release_agent);
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}
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sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root);
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/* Locate an existing or new sb for this hierarchy */
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sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts);
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if (IS_ERR(sb)) {
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kfree(root);
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return PTR_ERR(sb);
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ret = PTR_ERR(sb);
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kfree(opts.new_root);
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goto out_err;
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}
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if (sb->s_fs_info != root) {
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/* Reusing an existing superblock */
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BUG_ON(sb->s_root == NULL);
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kfree(root);
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root = NULL;
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} else {
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/* New superblock */
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root = sb->s_fs_info;
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BUG_ON(!root);
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if (root == opts.new_root) {
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/* We used the new root structure, so this is a new hierarchy */
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struct list_head tmp_cg_links;
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struct cgroup *root_cgrp = &root->top_cgroup;
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struct inode *inode;
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struct cgroupfs_root *existing_root;
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int i;
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BUG_ON(sb->s_root != NULL);
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@ -1105,6 +1167,18 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
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mutex_lock(&inode->i_mutex);
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mutex_lock(&cgroup_mutex);
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if (strlen(root->name)) {
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/* Check for name clashes with existing mounts */
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for_each_active_root(existing_root) {
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if (!strcmp(existing_root->name, root->name)) {
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ret = -EBUSY;
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&inode->i_mutex);
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goto drop_new_super;
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}
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}
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}
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/*
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* We're accessing css_set_count without locking
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* css_set_lock here, but that's OK - it can only be
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@ -1123,7 +1197,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
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if (ret == -EBUSY) {
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&inode->i_mutex);
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goto free_cg_links;
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free_cg_links(&tmp_cg_links);
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goto drop_new_super;
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}
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/* EBUSY should be the only error here */
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@ -1157,15 +1232,25 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
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cgroup_populate_dir(root_cgrp);
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mutex_unlock(&cgroup_mutex);
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mutex_unlock(&inode->i_mutex);
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} else {
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/*
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* We re-used an existing hierarchy - the new root (if
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* any) is not needed
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*/
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kfree(opts.new_root);
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}
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simple_set_mnt(mnt, sb);
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kfree(opts.release_agent);
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kfree(opts.name);
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return 0;
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free_cg_links:
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free_cg_links(&tmp_cg_links);
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drop_new_super:
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deactivate_locked_super(sb);
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out_err:
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kfree(opts.release_agent);
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kfree(opts.name);
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return ret;
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}
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@ -2992,6 +3077,9 @@ static int proc_cgroup_show(struct seq_file *m, void *v)
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seq_printf(m, "%lu:", root->subsys_bits);
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for_each_subsys(root, ss)
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seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
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if (strlen(root->name))
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seq_printf(m, "%sname=%s", count ? "," : "",
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root->name);
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seq_putc(m, ':');
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get_first_subsys(&root->top_cgroup, NULL, &subsys_id);
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cgrp = task_cgroup(tsk, subsys_id);
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