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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: Tejun Heo <tj@kernel.org>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2013-11-29 17:18:32 -05:00 committed by Greg Kroah-Hartman
parent fa736a951e
commit cf9e5a73aa
3 changed files with 115 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/kernfs/dir.c
View File

@ -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)
{

85
fs/kernfs/kernfs-internal.h
View File

@ -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

118
include/linux/kernfs.h
View File

@ -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; }