Hi,
On Wed, 19 Dec 2007, Serge E. Hallyn wrote:
> > I assume you mean S_REVOKE_LOCK and not ->i_mutex, right?
>
> No I did mean the i_mutex since you take the i_mutex when you set
> S_REVOKE_LOCK. So between that and the comment above do_lookup(),
> I assumed you were trying to lock out concurrent do_lookups() returning
> an inode whose revoke is starting at the same time.
No, I only use ->i_mutex for synchronizing the write to ->i_flags.
On Wed, 19 Dec 2007, Serge E. Hallyn wrote:
> > The caller is supposed to block open(2) with chmod(2)/chattr(2) so while
> > revoke is in progress, you can get references to the _revoked inode_,
> > which is fine (operations on it will fail with EBADFS). The
> > ->i_revoke_wait bits are there to make sure that while we revoke, you
> > can't get a _new reference_ to the inode until we're done.
>
> And a new reference means through iget(), so if revoke starts
> between the IS_REVOKE_LOCKED() check in do_lookup and its return,
> it's ok bc we'll get a reference later on?
Yes, as soon as we unhash the dentries and the inode, do_lookup() will try
to find a new inode with iget() but we need to wait before writeback on
the revoked inode is finished.
On Wed, 19 Dec 2007, Serge E. Hallyn wrote:
> I'm a little confused but i'll keep looking.
I don't blame you. The patch is missing the following "minor detail" which
is needed to avoid fs corruption...
Pekka
Index: 2.6/fs/revoke.c
===================================================================
--- 2.6.orig/fs/revoke.c 2007-12-16 19:57:40.000000000 +0200
+++ 2.6/fs/revoke.c 2007-12-19 18:03:13.000000000 +0200
@@ -426,6 +426,8 @@ int err = 0;
make_revoked_inode(inode);
remove_inode_hash(inode);
revoke_aliases(inode);
+
+ err = write_inode_now(inode, 1);
failed:
revoke_unlock(inode);
wake_up(&inode->i_revoke_wait);
--
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