Commit cf9e5a73 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

sysfs, kernfs: make sysfs_dirent definition public 



sysfs_dirent includes some information which should be available to
kernfs users - the type, flags, name and parent pointer.  This patch
moves sysfs_dirent definition from kernfs/kernfs-internal.h to
include/linux/kernfs.h so that kernfs users can access them.

The type part of flags is exported as enum kernfs_node_type, the flags
kernfs_node_flag, sysfs_type() and kernfs_enable_ns() are moved to
include/linux/kernfs.h and the former is updated to return the enum
type.  sysfs_dirent->s_parent and ->s_name are marked explicitly as
public.

This patch doesn't introduce any functional changes.

v2: Flags exported too and kernfs_enable_ns() definition moved.

v3: While moving kernfs_enable_ns() to include/linux/kernfs.h, v1 and
    v2 put the definition outside CONFIG_SYSFS replacing the dummy
    implementation with the actual implementation too.  Unfortunately,
    this can lead to oops when !CONFIG_SYSFS because
    kernfs_enable_ns() may be called on a NULL @sd and now tries to
    dereference @sd instead of not doing anything.  This issue was
    reported by Yuanhan Liu.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fa736a95

fs/kernfs/dir.c

+0 −15
Original line number Diff line number Diff line
@@ -895,21 +895,6 @@ int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent, 
	return error;

}



/**

 * kernfs_enable_ns - enable namespace under a directory

 * @sd: directory of interest, should be empty

 *

 * This is to be called right after @sd is created to enable namespace

 * under it.  All children of @sd must have non-NULL namespace tags and

 * only the ones which match the super_block's tag will be visible.

 */

void kernfs_enable_ns(struct sysfs_dirent *sd)

{

	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);

	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));

	sd->s_flags |= SYSFS_FLAG_NS;

}



/* Relationship between s_mode and the DT_xxx types */

static inline unsigned char dt_type(struct sysfs_dirent *sd)

{

fs/kernfs/kernfs-internal.h

+1 −84
Original line number Diff line number Diff line
@@ -13,102 +13,19 @@ 


#include <linux/lockdep.h>

#include <linux/fs.h>

#include <linux/rbtree.h>

#include <linux/mutex.h>



#include <linux/kernfs.h>



struct sysfs_open_dirent;



/* type-specific structures for sysfs_dirent->s_* union members */

struct sysfs_elem_dir {

	unsigned long		subdirs;

	/* children rbtree starts here and goes through sd->s_rb */

	struct rb_root		children;



	/*

	 * The kernfs hierarchy this directory belongs to.  This fits

	 * better directly in sysfs_dirent but is here to save space.

	 */

	struct kernfs_root	*root;

};



struct sysfs_elem_symlink {

	struct sysfs_dirent	*target_sd;

};



struct sysfs_elem_attr {

	const struct kernfs_ops	*ops;

	struct sysfs_open_dirent *open;

	loff_t			size;

};



struct sysfs_inode_attrs {

	struct iattr	ia_iattr;

	void		*ia_secdata;

	u32		ia_secdata_len;

};



/*

 * sysfs_dirent - the building block of sysfs hierarchy.  Each and

 * every sysfs node is represented by single sysfs_dirent.

 *

 * As long as s_count reference is held, the sysfs_dirent itself is

 * accessible.  Dereferencing s_elem or any other outer entity

 * requires s_active reference.

 */

struct sysfs_dirent {

	atomic_t		s_count;

	atomic_t		s_active;

#ifdef CONFIG_DEBUG_LOCK_ALLOC

	struct lockdep_map	dep_map;

#endif

	struct sysfs_dirent	*s_parent;

	const char		*s_name;



	struct rb_node		s_rb;



	union {

		struct completion	*completion;

		struct sysfs_dirent	*removed_list;

	} u;



	const void		*s_ns; /* namespace tag */

	unsigned int		s_hash; /* ns + name hash */

	union {

		struct sysfs_elem_dir		s_dir;

		struct sysfs_elem_symlink	s_symlink;

		struct sysfs_elem_attr		s_attr;

	};



	void			*priv;



	unsigned short		s_flags;

	umode_t			s_mode;

	unsigned int		s_ino;

	struct sysfs_inode_attrs *s_iattr;

};



#define SD_DEACTIVATED_BIAS		INT_MIN



#define SYSFS_TYPE_MASK			0x000f

#define SYSFS_DIR			0x0001

#define SYSFS_KOBJ_ATTR			0x0002

#define SYSFS_KOBJ_LINK			0x0004

#define SYSFS_COPY_NAME			(SYSFS_DIR | SYSFS_KOBJ_LINK)

#define SYSFS_ACTIVE_REF		SYSFS_KOBJ_ATTR



#define SYSFS_FLAG_MASK			~SYSFS_TYPE_MASK

#define SYSFS_FLAG_REMOVED		0x0010

#define SYSFS_FLAG_NS			0x0020

#define SYSFS_FLAG_HAS_SEQ_SHOW		0x0040

#define SYSFS_FLAG_HAS_MMAP		0x0080

#define SYSFS_FLAG_LOCKDEP		0x0100



static inline unsigned int sysfs_type(struct sysfs_dirent *sd)

{

	return sd->s_flags & SYSFS_TYPE_MASK;

}

/* SYSFS_TYPE_MASK and types are defined in include/linux/kernfs.h */



/**

 * kernfs_root - find out the kernfs_root a sysfs_dirent belongs to

include/linux/kernfs.h

+114 −4
Original line number Diff line number Diff line
@@ -13,6 +13,9 @@ 
#include <linux/mutex.h>

#include <linux/idr.h>

#include <linux/lockdep.h>

#include <linux/rbtree.h>

#include <linux/atomic.h>

#include <linux/completion.h>



struct file;

struct iattr;
@@ -21,7 +24,92 @@ struct vm_area_struct; 
struct super_block;

struct file_system_type;



struct sysfs_dirent;

struct sysfs_open_dirent;

struct sysfs_inode_attrs;



enum kernfs_node_type {

	SYSFS_DIR		= 0x0001,

	SYSFS_KOBJ_ATTR		= 0x0002,

	SYSFS_KOBJ_LINK		= 0x0004,

};



#define SYSFS_TYPE_MASK		0x000f

#define SYSFS_COPY_NAME		(SYSFS_DIR | SYSFS_KOBJ_LINK)

#define SYSFS_ACTIVE_REF	SYSFS_KOBJ_ATTR

#define SYSFS_FLAG_MASK		~SYSFS_TYPE_MASK



enum kernfs_node_flag {

	SYSFS_FLAG_REMOVED	= 0x0010,

	SYSFS_FLAG_NS		= 0x0020,

	SYSFS_FLAG_HAS_SEQ_SHOW	= 0x0040,

	SYSFS_FLAG_HAS_MMAP	= 0x0080,

	SYSFS_FLAG_LOCKDEP	= 0x0100,

};



/* type-specific structures for sysfs_dirent->s_* union members */

struct sysfs_elem_dir {

	unsigned long		subdirs;

	/* children rbtree starts here and goes through sd->s_rb */

	struct rb_root		children;



	/*

	 * The kernfs hierarchy this directory belongs to.  This fits

	 * better directly in sysfs_dirent but is here to save space.

	 */

	struct kernfs_root	*root;

};



struct sysfs_elem_symlink {

	struct sysfs_dirent	*target_sd;

};



struct sysfs_elem_attr {

	const struct kernfs_ops	*ops;

	struct sysfs_open_dirent *open;

	loff_t			size;

};



/*

 * sysfs_dirent - the building block of sysfs hierarchy.  Each and every

 * sysfs node is represented by single sysfs_dirent.  Most fields are

 * private to kernfs and shouldn't be accessed directly by kernfs users.

 *

 * As long as s_count reference is held, the sysfs_dirent itself is

 * accessible.  Dereferencing s_elem or any other outer entity

 * requires s_active reference.

 */

struct sysfs_dirent {

	atomic_t		s_count;

	atomic_t		s_active;

#ifdef CONFIG_DEBUG_LOCK_ALLOC

	struct lockdep_map	dep_map;

#endif

	/* the following two fields are published */

	struct sysfs_dirent	*s_parent;

	const char		*s_name;



	struct rb_node		s_rb;



	union {

		struct completion	*completion;

		struct sysfs_dirent	*removed_list;

	} u;



	const void		*s_ns; /* namespace tag */

	unsigned int		s_hash; /* ns + name hash */

	union {

		struct sysfs_elem_dir		s_dir;

		struct sysfs_elem_symlink	s_symlink;

		struct sysfs_elem_attr		s_attr;

	};



	void			*priv;



	unsigned short		s_flags;

	umode_t			s_mode;

	unsigned int		s_ino;

	struct sysfs_inode_attrs *s_iattr;

};



struct kernfs_root {

	/* published fields */
@@ -82,6 +170,26 @@ struct kernfs_ops { 


#ifdef CONFIG_SYSFS



static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)

{

	return sd->s_flags & SYSFS_TYPE_MASK;

}



/**

 * kernfs_enable_ns - enable namespace under a directory

 * @sd: directory of interest, should be empty

 *

 * This is to be called right after @sd is created to enable namespace

 * under it.  All children of @sd must have non-NULL namespace tags and

 * only the ones which match the super_block's tag will be visible.

 */

static inline void kernfs_enable_ns(struct sysfs_dirent *sd)

{

	WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR);

	WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children));

	sd->s_flags |= SYSFS_FLAG_NS;

}



struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent,

					    const char *name, const void *ns);

void kernfs_get(struct sysfs_dirent *sd);
@@ -107,7 +215,6 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name, 
			     const void *ns);

int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,

		     const char *new_name, const void *new_ns);

void kernfs_enable_ns(struct sysfs_dirent *sd);

int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);

void kernfs_notify(struct sysfs_dirent *sd);
@@ -120,6 +227,11 @@ void kernfs_init(void); 


#else	/* CONFIG_SYSFS */



static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd)

{ return 0; }	/* whatever */



static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }



static inline struct sysfs_dirent *

kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name,

		       const void *ns)
@@ -161,8 +273,6 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd, 
				   const char *new_name, const void *new_ns)

{ return -ENOSYS; }



static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }



static inline int kernfs_setattr(struct sysfs_dirent *sd,

				 const struct iattr *iattr)

{ return -ENOSYS; }

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