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authorTejun Heo <tj@kernel.org>2014-02-03 23:09:15 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-08 04:00:41 +0400
commit0c23b2259a4850494e2c53e864ea840597c6cdd3 (patch)
treef4d061ea433e443edd43d1f0a186e06aeb2ed95e
parent2536390da0d300b2734c721235c082498879841d (diff)
downloadlinux-0c23b2259a4850494e2c53e864ea840597c6cdd3.tar.xz
kernfs: implement kernfs_node_from_dentry(), kernfs_root_from_sb() and kernfs_rename()
Implement helpers to determine node from dentry and root from super_block. Also add a kernfs_rename_ns() wrapper which assumes NULL namespace. These generally make sense and will be used by cgroup. v2: Some dummy implementations for !CONFIG_SYSFS was missing. Fixed. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/kernfs/dir.c18
-rw-r--r--fs/kernfs/mount.c14
-rw-r--r--include/linux/kernfs.h16
3 files changed, 48 insertions, 0 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 3cff0a233cd1..42a250f83b98 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -350,6 +350,24 @@ const struct dentry_operations kernfs_dops = {
.d_release = kernfs_dop_release,
};
+/**
+ * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
+ * @dentry: the dentry in question
+ *
+ * Return the kernfs_node associated with @dentry. If @dentry is not a
+ * kernfs one, %NULL is returned.
+ *
+ * While the returned kernfs_node will stay accessible as long as @dentry
+ * is accessible, the returned node can be in any state and the caller is
+ * fully responsible for determining what's accessible.
+ */
+struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
+{
+ if (dentry->d_op == &kernfs_dops)
+ return dentry->d_fsdata;
+ return NULL;
+}
+
static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
const char *name, umode_t mode,
unsigned flags)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 70cc6983d9b5..e5b28b0ebc37 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -48,6 +48,20 @@ static const struct super_operations kernfs_sops = {
.show_options = kernfs_sop_show_options,
};
+/**
+ * kernfs_root_from_sb - determine kernfs_root associated with a super_block
+ * @sb: the super_block in question
+ *
+ * Return the kernfs_root associated with @sb. If @sb is not a kernfs one,
+ * %NULL is returned.
+ */
+struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
+{
+ if (sb->s_op == &kernfs_sops)
+ return kernfs_info(sb)->root;
+ return NULL;
+}
+
static int kernfs_fill_super(struct super_block *sb)
{
struct kernfs_super_info *info = kernfs_info(sb);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 9ca0f09757a1..9c899040c05e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -234,6 +234,9 @@ struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
void kernfs_get(struct kernfs_node *kn);
void kernfs_put(struct kernfs_node *kn);
+struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
+struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
+
struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
unsigned int flags, void *priv);
void kernfs_destroy_root(struct kernfs_root *root);
@@ -288,6 +291,12 @@ kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
static inline void kernfs_get(struct kernfs_node *kn) { }
static inline void kernfs_put(struct kernfs_node *kn) { }
+static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
+{ return NULL; }
+
+static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
+{ return NULL; }
+
static inline struct kernfs_root *
kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
void *priv)
@@ -388,6 +397,13 @@ static inline int kernfs_remove_by_name(struct kernfs_node *parent,
return kernfs_remove_by_name_ns(parent, name, NULL);
}
+static inline int kernfs_rename(struct kernfs_node *kn,
+ struct kernfs_node *new_parent,
+ const char *new_name)
+{
+ return kernfs_rename_ns(kn, new_parent, new_name, NULL);
+}
+
static inline struct dentry *
kernfs_mount(struct file_system_type *fs_type, int flags,
struct kernfs_root *root)