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/ceph/caps.c b/fs/ceph/caps.c
index c69e125..cdbf8cf 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2030,7 +2030,7 @@
 	if (datasync)
 		goto out;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	dirty = try_flush_caps(inode, &flush_tid);
 	dout("fsync dirty caps are %s\n", ceph_cap_string(dirty));
@@ -2046,7 +2046,7 @@
 		ret = wait_event_interruptible(ci->i_cap_wq,
 					caps_are_flushed(inode, flush_tid));
 	}
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 out:
 	dout("fsync %p%s result=%d\n", inode, datasync ? " datasync" : "", ret);
 	return ret;