sysfs, kernfs: introduce kernfs_notify()

Introduce kernfs interface to wake up poll(2) which takes and returns
sysfs_dirents.

sysfs_notify_dirent() is renamed to kernfs_notify() and sysfs_notify()
is updated so that it doesn't directly grab sysfs_mutex but acquires
the target sysfs_dirents using sysfs_get_dirent().
sysfs_notify_dirent() is reimplemented as a dumb inline wrapper around
kernfs_notify().

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 8 insertions, 4 deletions

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index ba993ebcd81e..f20796ecc76e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -84,6 +84,7 @@ 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);
 
 #else   /* CONFIG_SYSFS */
 
@@ -120,6 +121,8 @@ static inline int kernfs_setattr(struct sysfs_dirent *sd,
                                  const struct iattr *iattr)
 { return -ENOSYS; }
 
+static inline void kernfs_notify(struct sysfs_dirent *sd) { }
+
 #endif  /* CONFIG_SYSFS */
 
 static inline struct sysfs_dirent *
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 2bc735d3e938..0ab2b023b613 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -243,7 +243,6 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
                                   const char *link_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
-void sysfs_notify_dirent(struct sysfs_dirent *sd);
 struct sysfs_dirent *sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd,
                                          const unsigned char *name,
                                          const void *ns);
@@ -418,9 +417,6 @@ static inline void sysfs_notify(struct kobject *kobj, const char *dir,
                                 const char *attr)
 {
 }
-static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
-{
-}
 static inline struct sysfs_dirent *
 sysfs_get_dirent_ns(struct sysfs_dirent *parent_sd, const unsigned char *name,
                     const void *ns)
@@ -466,4 +462,9 @@ sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
         return sysfs_get_dirent_ns(parent_sd, name, NULL);
 }
 
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+        kernfs_notify(sd);
+}
+
 #endif /* _SYSFS_H_ */