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Commit bd96f76a authored by Tejun Heo's avatar Tejun Heo
Browse files

kernfs: implement kernfs_walk_and_get() 



Implement kernfs_walk_and_get() which is similar to
kernfs_find_and_get() but can walk a path instead of just a name.

v2: Use strlcpy() instead of strlen() + memcpy() as suggested by
    David.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Miller <davem@davemloft.net>
parent b11cfb58

fs/kernfs/dir.c

+46 −0
Original line number Diff line number Diff line
@@ -694,6 +694,29 @@ static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, 
	return NULL;

}



static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,

					  const unsigned char *path,

					  const void *ns)

{

	static char path_buf[PATH_MAX];	/* protected by kernfs_mutex */

	size_t len = strlcpy(path_buf, path, PATH_MAX);

	char *p = path_buf;

	char *name;



	lockdep_assert_held(&kernfs_mutex);



	if (len >= PATH_MAX)

		return NULL;



	while ((name = strsep(&p, "/")) && parent) {

		if (*name == '\0')

			continue;

		parent = kernfs_find_ns(parent, name, ns);

	}



	return parent;

}



/**

 * kernfs_find_and_get_ns - find and get kernfs_node with the given name

 * @parent: kernfs_node to search under
@@ -718,6 +741,29 @@ struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, 
}

EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns);



/**

 * kernfs_walk_and_get_ns - find and get kernfs_node with the given path

 * @parent: kernfs_node to search under

 * @path: path to look for

 * @ns: the namespace tag to use

 *

 * Look for kernfs_node with path @path under @parent and get a reference

 * if found.  This function may sleep and returns pointer to the found

 * kernfs_node on success, %NULL on failure.

 */

struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,

					   const char *path, const void *ns)

{

	struct kernfs_node *kn;



	mutex_lock(&kernfs_mutex);

	kn = kernfs_walk_ns(parent, path, ns);

	kernfs_get(kn);

	mutex_unlock(&kernfs_mutex);



	return kn;

}



/**

 * kernfs_create_root - create a new kernfs hierarchy

 * @scops: optional syscall operations for the hierarchy

include/linux/kernfs.h

+12 −0
Original line number Diff line number Diff line
@@ -274,6 +274,8 @@ void pr_cont_kernfs_path(struct kernfs_node *kn); 
struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn);

struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,

					   const char *name, const void *ns);

struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,

					   const char *path, const void *ns);

void kernfs_get(struct kernfs_node *kn);

void kernfs_put(struct kernfs_node *kn);
@@ -350,6 +352,10 @@ static inline struct kernfs_node * 
kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,

		       const void *ns)

{ return NULL; }

static inline struct kernfs_node *

kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path,

		       const void *ns)

{ return NULL; }



static inline void kernfs_get(struct kernfs_node *kn) { }

static inline void kernfs_put(struct kernfs_node *kn) { }
@@ -430,6 +436,12 @@ kernfs_find_and_get(struct kernfs_node *kn, const char *name) 
	return kernfs_find_and_get_ns(kn, name, NULL);

}



static inline struct kernfs_node *

kernfs_walk_and_get(struct kernfs_node *kn, const char *path)

{

	return kernfs_walk_and_get_ns(kn, path, NULL);

}



static inline struct kernfs_node *

kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,

		  void *priv)