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Commit 0c23b225 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2536390d

fs/kernfs/dir.c

+18 −0
Original line number Diff line number Diff line
@@ -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)

fs/kernfs/mount.c

+14 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/kernfs.h

+16 −0
Original line number Diff line number Diff line
@@ -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)