Messages in this thread Patch in this message | | | Date | Wed, 19 Dec 2007 22:23:30 +0200 (EET) | From | Pekka J Enberg <> | Subject | Re: [RFC/PATCH 2/8] revoke: inode revoke lock V7 |
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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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