summaryrefslogtreecommitdiffstats
path: root/kernel/cgroup.c
diff options
context:
space:
mode:
authorAristeu Rozanski <aris@redhat.com>2012-08-23 16:53:30 -0400
committerTejun Heo <tj@kernel.org>2012-08-24 15:55:33 -0700
commit03b1cde6b22f625ae832b939bc7379ec1466aec5 (patch)
tree0aecdc872a6ab2a00a8026e1898d4f3492cca87b /kernel/cgroup.c
parent13af07df9b7e49f1987cf36aa048dc6c49d0f93d (diff)
downloadlinux-03b1cde6b22f625ae832b939bc7379ec1466aec5.tar.bz2
cgroup: add xattr support
This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c100
1 files changed, 93 insertions, 7 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 875a7130647c..508b4a97ab19 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -276,7 +276,8 @@ 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_NOPREFIX, /* mounted subsystems have no named prefix */
+ ROOT_XATTR, /* supports extended attributes */
};
static int cgroup_is_releasable(const struct cgroup *cgrp)
@@ -913,15 +914,19 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
*/
BUG_ON(!list_empty(&cgrp->pidlists));
+ simple_xattrs_free(&cgrp->xattrs);
+
kfree_rcu(cgrp, rcu_head);
} else {
struct cfent *cfe = __d_cfe(dentry);
struct cgroup *cgrp = dentry->d_parent->d_fsdata;
+ struct cftype *cft = cfe->type;
WARN_ONCE(!list_empty(&cfe->node) &&
cgrp != &cgrp->root->top_cgroup,
"cfe still linked for %s\n", cfe->type->name);
kfree(cfe);
+ simple_xattrs_free(&cft->xattrs);
}
iput(inode);
}
@@ -1140,6 +1145,8 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
seq_printf(seq, ",%s", ss->name);
if (test_bit(ROOT_NOPREFIX, &root->flags))
seq_puts(seq, ",noprefix");
+ if (test_bit(ROOT_XATTR, &root->flags))
+ seq_puts(seq, ",xattr");
if (strlen(root->release_agent_path))
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
if (clone_children(&root->top_cgroup))
@@ -1208,6 +1215,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
opts->clone_children = true;
continue;
}
+ if (!strcmp(token, "xattr")) {
+ set_bit(ROOT_XATTR, &opts->flags);
+ continue;
+ }
if (!strncmp(token, "release_agent=", 14)) {
/* Specifying two release agents is forbidden */
if (opts->release_agent)
@@ -1425,6 +1436,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
mutex_init(&cgrp->pidlist_mutex);
INIT_LIST_HEAD(&cgrp->event_list);
spin_lock_init(&cgrp->event_list_lock);
+ simple_xattrs_init(&cgrp->xattrs);
}
static void init_cgroup_root(struct cgroupfs_root *root)
@@ -1769,6 +1781,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
mutex_unlock(&cgroup_root_mutex);
mutex_unlock(&cgroup_mutex);
+ simple_xattrs_free(&cgrp->xattrs);
+
kill_litter_super(sb);
cgroup_drop_root(root);
}
@@ -2575,6 +2589,64 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry,
return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
}
+static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
+{
+ if (S_ISDIR(dentry->d_inode->i_mode))
+ return &__d_cgrp(dentry)->xattrs;
+ else
+ return &__d_cft(dentry)->xattrs;
+}
+
+static inline int xattr_enabled(struct dentry *dentry)
+{
+ struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
+ return test_bit(ROOT_XATTR, &root->flags);
+}
+
+static bool is_valid_xattr(const char *name)
+{
+ if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
+ !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN))
+ return true;
+ return false;
+}
+
+static int cgroup_setxattr(struct dentry *dentry, const char *name,
+ const void *val, size_t size, int flags)
+{
+ if (!xattr_enabled(dentry))
+ return -EOPNOTSUPP;
+ if (!is_valid_xattr(name))
+ return -EINVAL;
+ return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags);
+}
+
+static int cgroup_removexattr(struct dentry *dentry, const char *name)
+{
+ if (!xattr_enabled(dentry))
+ return -EOPNOTSUPP;
+ if (!is_valid_xattr(name))
+ return -EINVAL;
+ return simple_xattr_remove(__d_xattrs(dentry), name);
+}
+
+static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name,
+ void *buf, size_t size)
+{
+ if (!xattr_enabled(dentry))
+ return -EOPNOTSUPP;
+ if (!is_valid_xattr(name))
+ return -EINVAL;
+ return simple_xattr_get(__d_xattrs(dentry), name, buf, size);
+}
+
+static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size)
+{
+ if (!xattr_enabled(dentry))
+ return -EOPNOTSUPP;
+ return simple_xattr_list(__d_xattrs(dentry), buf, size);
+}
+
static const struct file_operations cgroup_file_operations = {
.read = cgroup_file_read,
.write = cgroup_file_write,
@@ -2583,11 +2655,22 @@ static const struct file_operations cgroup_file_operations = {
.release = cgroup_file_release,
};
+static const struct inode_operations cgroup_file_inode_operations = {
+ .setxattr = cgroup_setxattr,
+ .getxattr = cgroup_getxattr,
+ .listxattr = cgroup_listxattr,
+ .removexattr = cgroup_removexattr,
+};
+
static const struct inode_operations cgroup_dir_inode_operations = {
.lookup = cgroup_lookup,
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.rename = cgroup_rename,
+ .setxattr = cgroup_setxattr,
+ .getxattr = cgroup_getxattr,
+ .listxattr = cgroup_listxattr,
+ .removexattr = cgroup_removexattr,
};
static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
@@ -2635,6 +2718,7 @@ static int cgroup_create_file(struct dentry *dentry, umode_t mode,
} else if (S_ISREG(mode)) {
inode->i_size = 0;
inode->i_fop = &cgroup_file_operations;
+ inode->i_op = &cgroup_file_inode_operations;
}
d_instantiate(dentry, inode);
dget(dentry); /* Extra count - pin the dentry in core */
@@ -2695,7 +2779,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
}
static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
- const struct cftype *cft)
+ struct cftype *cft)
{
struct dentry *dir = cgrp->dentry;
struct cgroup *parent = __d_cgrp(dir);
@@ -2705,6 +2789,8 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
umode_t mode;
char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
+ simple_xattrs_init(&cft->xattrs);
+
/* does @cft->flags tell us to skip creation on @cgrp? */
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
return 0;
@@ -2745,9 +2831,9 @@ out:
}
static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
- const struct cftype cfts[], bool is_add)
+ struct cftype cfts[], bool is_add)
{
- const struct cftype *cft;
+ struct cftype *cft;
int err, ret = 0;
for (cft = cfts; cft->name[0] != '\0'; cft++) {
@@ -2781,7 +2867,7 @@ static void cgroup_cfts_prepare(void)
}
static void cgroup_cfts_commit(struct cgroup_subsys *ss,
- const struct cftype *cfts, bool is_add)
+ struct cftype *cfts, bool is_add)
__releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
{
LIST_HEAD(pending);
@@ -2832,7 +2918,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss,
* function currently returns 0 as long as @cfts registration is successful
* even if some file creation attempts on existing cgroups fail.
*/
-int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype_set *set;
@@ -2862,7 +2948,7 @@ EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
* registered with @ss.
*/
-int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype_set *set;