sysfs: use ilookup5() instead of ilookup5_nowait()

As inode creation is protected by sysfs_mutex, ilookup5_nowait()
always either fails to find at all or finds one which is fully
initialized, so using ilookup5_nowait() or ilookup5() doesn't make any
difference. Switch to ilookup5() as it's planned to be removed. This
change also makes lookup return value handling a bit simpler.

This change was suggested by Al Viro.

Signed-off-by: Tejun Heo <[e-mail]>
Cc: Al Viro <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

fs/sysfs/dir.c

···
 	memset(acxt, 0, sizeof(*acxt));
 	acxt->parent_sd = parent_sd;
 
-	/* Lookup parent inode.  inode initialization and I_NEW
-	 * clearing are protected by sysfs_mutex.  By grabbing it and
-	 * looking up with _nowait variant, inode state can be
-	 * determined reliably.
+	/* Lookup parent inode.  inode initialization is protected by
+	 * sysfs_mutex, so inode existence can be determined by
+	 * looking up inode while holding sysfs_mutex.
 	 */
 	mutex_lock(&sysfs_mutex);
 
-	inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
-				parent_sd);
+	inode = ilookup5(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
+			 parent_sd);
+	if (inode) {
+		WARN_ON(inode->i_state & I_NEW);
 
-	if (inode && !(inode->i_state & I_NEW)) {
 		/* parent inode available */
 		acxt->parent_inode = inode;
 
···
 			mutex_lock(&inode->i_mutex);
 			mutex_lock(&sysfs_mutex);
 		}
-	} else
-		iput(inode);
+	}
 }
 
 /**