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>

1 files changed, 1 insertions, 84 deletions

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index ced0d6dadc7d..f33a7844e8fd 100644
--- 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