sysfs: In sysfs_chmod_file lazily propagate the mode change.

Now that sysfs_getattr and sysfs_permission refresh the vfs
inode there is no need to immediatly push the mode change
into the vfs cache.  Reducing the amount of work needed and
simplifying the locking.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 23 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index faa1a803caa9..dc30d9e31683 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -579,38 +579,23 @@ EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
  */
 int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
 {
-        struct sysfs_dirent *victim_sd = NULL;
-        struct dentry *victim = NULL;
-        struct inode * inode;
+        struct sysfs_dirent *sd;
         struct iattr newattrs;
         int rc;
 
-        rc = -ENOENT;
-        victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
-        if (!victim_sd)
-                goto out;
+        mutex_lock(&sysfs_mutex);
 
-        mutex_lock(&sysfs_rename_mutex);
-        victim = sysfs_get_dentry(victim_sd);
-        mutex_unlock(&sysfs_rename_mutex);
-        if (IS_ERR(victim)) {
-                rc = PTR_ERR(victim);
-                victim = NULL;
+        rc = -ENOENT;
+        sd = sysfs_find_dirent(kobj->sd, attr->name);
+        if (!sd)
                 goto out;
-        }
-
-        inode = victim->d_inode;
 
-        mutex_lock(&inode->i_mutex);
-
-        newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
+        newattrs.ia_mode = (mode & S_IALLUGO) | (sd->s_mode & ~S_IALLUGO);
         newattrs.ia_valid = ATTR_MODE;
-        rc = sysfs_setattr(victim, &newattrs);
+        rc = sysfs_sd_setattr(sd, &newattrs);
 
-        mutex_unlock(&inode->i_mutex);
  out:
-        dput(victim);
-        sysfs_put(victim_sd);
+        mutex_unlock(&sysfs_mutex);
         return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);