wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d964195..83bc8bf 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3231,7 +3231,7 @@
 	overwrite = *((int *)iocb->private);
 
 	if (overwrite)
-		mutex_unlock(&inode->i_mutex);
+		inode_unlock(inode);
 
 	/*
 	 * We could direct write to holes and fallocate.
@@ -3331,7 +3331,7 @@
 		inode_dio_end(inode);
 	/* take i_mutex locking again if we do a ovewrite dio */
 	if (overwrite)
-		mutex_lock(&inode->i_mutex);
+		inode_lock(inode);
 
 	return ret;
 }
@@ -3653,7 +3653,7 @@
 	handle_t *handle;
 	loff_t size = i_size_read(inode);
 
-	WARN_ON(!mutex_is_locked(&inode->i_mutex));
+	WARN_ON(!inode_is_locked(inode));
 	if (offset > size || offset + len < size)
 		return 0;
 
@@ -3707,7 +3707,7 @@
 			return ret;
 	}
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	/* No need to punch hole beyond i_size */
 	if (offset >= inode->i_size)
@@ -3809,7 +3809,7 @@
 	up_write(&EXT4_I(inode)->i_mmap_sem);
 	ext4_inode_resume_unlocked_dio(inode);
 out_mutex:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return ret;
 }
 
@@ -3879,7 +3879,7 @@
 	 * have i_mutex locked because it's not necessary.
 	 */
 	if (!(inode->i_state & (I_NEW|I_FREEING)))
-		WARN_ON(!mutex_is_locked(&inode->i_mutex));
+		WARN_ON(!inode_is_locked(inode));
 	trace_ext4_truncate_enter(inode);
 
 	if (!ext4_can_truncate(inode))