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/include/linux/kernfs.h b/include/linux/kernfs.h
index 75fcbe5..faaf4f2 100644
--- 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 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 @@
#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 @@
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 @@
#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 @@
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; }