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>

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index eaffa83..7c5b517 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -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)
 {

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index ced0d6d..f33a784 100644 (file)
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -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

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 75fcbe5..faaf4f2 100644 (file)
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -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; }