[Ocfs2-devel] [PATCH] fix big 116 -- umount cause crash after some operation

[Mark Fasheh]

On Wed, Aug 25, 2004 at 09:04:39AM +0800, Ling, Xiaofeng wrote:
> So what we see is not the same. 
> The bug 116 is easy to reproduce, just do a command line as
> root#mkdir /ocfs/aaa;umount /ocfs
> follow the umount to mkdir tightly.
Ok, I think I see what's going on here.

if I do this:

mkdir /ocfs2/foobar/baz; umount /ocfs2

assuming that foobar was created a while ago so the commit thread has no
work currently then the umount goes through fine, we wait on the commit
thread and he flushes everything.

however,

mkdir /ocfs/foo; umount /ocfs2

will crash things almost immediately. What's the only difference there?
Basically that the root inode is in the commit thread on the second case.

What I believe is happening is that umount succeeds without calling
clear_inode on the root inode because we still have a reference on it, so
none of the actual work for umounting has been done, yet umount exits.
That'd explain the busy inodes message we always get and the random crashes
in one or the other ocfs2 thread.

Can you try this patch and see if it reproduces? Running with this, I can't
get it to crash any more :) We did dismount from clear_inode for historical
reasons having to do with some data structures we used to alloc on the
inodes. We no longer have those issues due to our sane handling of inode
private nowadays, so I think it's fine to actually umount from our put_super
method like other file systems :)
	--Mark

--
Mark Fasheh
Software Developer, Oracle Corp
mark.fasheh at oracle.com

Index: super.c
===================================================================
--- super.c	(revision 1383)
+++ super.c	(working copy)
@@ -712,7 +712,8 @@ static void ocfs_put_super (struct super
 	LOG_ENTRY_ARGS ("(0x%p)\n", sb);
 
 	ocfs_sync_blockdev(sb);
-	LOG_TRACE_STR ("put super... do nothing!  DONE!!!!");
+	ocfs_dismount_volume (sb);
+
 	LOG_EXIT ();
 
 	LOG_CLEAR_CONTEXT();
Index: inode.c
===================================================================
--- inode.c	(revision 1383)
+++ inode.c	(working copy)
@@ -757,15 +757,6 @@ void ocfs_clear_inode (struct inode *ino
 	ocfs_extent_map_destroy (&OCFS_I(inode)->ip_ext_map);
 	ocfs_extent_map_init (&OCFS_I(inode)->ip_ext_map);
 
-	if (inode == osb->root_inode) {
-		LOG_TRACE_STR("this is the root inode, doing cleanup now!");
-		ocfs_sync_blockdev(inode->i_sb);
-		LOG_TRACE_STR ("syncing past root inode");
-		LOG_TRACE_STR ("calling dismount");
-		ocfs_dismount_volume (inode->i_sb);
-		goto bail;
-	}
-
 	down(&recovery_list_sem);
 	list_del(&OCFS_I(inode)->ip_recovery_list);
 	up(&recovery_list_sem);