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authorTejun Heo <tj@kernel.org>2014-05-13 20:16:21 +0400
committerTejun Heo <tj@kernel.org>2014-05-13 20:16:21 +0400
commitb41686401e501430ffe93b575ef7959d2ecc6f2e (patch)
tree9d38bb6b2878c3107aaad43ab53ac145c4ed9a9e /include/linux/cgroup.h
parentec903c0c858e4963a9e0724bdcadfa837253341c (diff)
downloadlinux-b41686401e501430ffe93b575ef7959d2ecc6f2e.tar.xz
cgroup: implement cftype->write()
During the recent conversion to kernfs, cftype's seq_file operations are updated so that they are directly mapped to kernfs operations and thus can fully access the associated kernfs and cgroup contexts; however, write path hasn't seen similar updates and none of the existing write operations has access to, for example, the associated kernfs_open_file. Let's introduce a new operation cftype->write() which maps directly to the kernfs write operation and has access to all the arguments and contexts. This will replace ->write_string() and ->trigger() and ease manipulation of kernfs active protection from cgroup file operations. Two accessors - of_cft() and of_css() - are introduced to enable accessing the associated cgroup context from cftype->write() which only takes kernfs_open_file for the context information. The accessors for seq_file operations - seq_cft() and seq_css() - are rewritten to wrap the of_ accessors. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h27
1 files changed, 23 insertions, 4 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c5f3684ef557..c5a170ca4a48 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -515,6 +515,15 @@ struct cftype {
*/
int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
+ /*
+ * write() is the generic write callback which maps directly to
+ * kernfs write operation and overrides all other operations.
+ * Maximum write size is determined by ->max_write_len. Use
+ * of_css/cft() to access the associated css and cft.
+ */
+ ssize_t (*write)(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off);
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lock_class_key lockdep_key;
#endif
@@ -552,14 +561,24 @@ static inline ino_t cgroup_ino(struct cgroup *cgrp)
return 0;
}
-static inline struct cftype *seq_cft(struct seq_file *seq)
+/* cft/css accessors for cftype->write() operation */
+static inline struct cftype *of_cft(struct kernfs_open_file *of)
{
- struct kernfs_open_file *of = seq->private;
-
return of->kn->priv;
}
-struct cgroup_subsys_state *seq_css(struct seq_file *seq);
+struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
+
+/* cft/css accessors for cftype->seq_*() operations */
+static inline struct cftype *seq_cft(struct seq_file *seq)
+{
+ return of_cft(seq->private);
+}
+
+static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
+{
+ return of_css(seq->private);
+}
/*
* Name / path handling functions. All are thin wrappers around the kernfs