[PATCH] sysfs: add sysfs_chmod_file()

sysfs: allow changing the permissions for already created attributes

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 352f966a1174..da25aeb0e062 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -428,6 +428,41 @@ int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
 
 
 /**
+ * sysfs_chmod_file - update the modified mode value on an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ * @mode: file permissions.
+ *
+ */
+int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
+{
+        struct dentry *dir = kobj->dentry;
+        struct dentry *victim;
+        struct sysfs_dirent *sd;
+        umode_t umode = (mode & S_IALLUGO) | S_IFREG;
+        int res = -ENOENT;
+
+        down(&dir->d_inode->i_sem);
+        victim = sysfs_get_dentry(dir, attr->name);
+        if (!IS_ERR(victim)) {
+                if (victim->d_inode &&
+                    (victim->d_parent->d_inode == dir->d_inode)) {
+                        sd = victim->d_fsdata;
+                        attr->mode = mode;
+                        sd->s_mode = umode;
+                        victim->d_inode->i_mode = umode;
+                        dput(victim);
+                        res = 0;
+                }
+        }
+        up(&dir->d_inode->i_sem);
+
+        return res;
+}
+EXPORT_SYMBOL_GPL(sysfs_chmod_file);
+
+
+/**
  *      sysfs_remove_file - remove an object attribute.
  *      @kobj:  object we're acting for.
  *      @attr:  attribute descriptor.