sysfs, kernfs: introduce kernfs_setattr()

Introduce kernfs setattr interface - kernfs_setattr().

sysfs_sd_setattr() is renamed to __kernfs_setattr() and
kernfs_setattr() is a simple wrapper around it with sysfs_mutex
locking.  sysfs_chmod_file() is updated to get an explicit ref on
kobj->sd and then invoke kernfs_setattr() so that it doesn't have to
use internal interface.

This patch doesn't introduce any behavior differences.

v2: Dummy implementation for !CONFIG_SYSFS updated to return -ENOSYS.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 803d9600cf72..8cb673875715 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -10,6 +10,9 @@
 #include <linux/kernel.h>
 #include <linux/err.h>
 
+struct file;
+struct iattr;
+
 struct sysfs_dirent;
 
 #ifdef CONFIG_SYSFS
@@ -22,6 +25,7 @@ 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);
+int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
 
 #else	/* CONFIG_SYSFS */
 
@@ -41,6 +45,10 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
 				   const char *new_name, const void *new_ns)
 { return -ENOSYS; }
 
+static inline int kernfs_setattr(struct sysfs_dirent *sd,
+				 const struct iattr *iattr)
+{ return -ENOSYS; }
+
 #endif	/* CONFIG_SYSFS */
 
 static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,