[Ocfs2-devel] [PATCH 2/2] Ocfs2: Handle deletion of reflinked oprhan inodes correctly.

[Joel Becker]

On Fri, Mar 19, 2010 at 04:50:47PM -0700, Mark Fasheh wrote:
> On Fri, Mar 19, 2010 at 09:21:10AM +0800, Tristan Ye wrote:
> > Current rule of orphan dir is that all inodes in the orphan dir
> > have ORPHANED_FL, otherwise we treated it as an ERROR. this rule
> > works well except for some rare cases of reflink operation:
> > 
> > http://oss.oracle.com/bugzilla/show_bug.cgi?id=1215
> > 
> > The problem is introduced by the essense of how reflink and our
> > orphan_scan thread were working:
> > 
> >  * Orphan_scan scan the orphan dir into a queue first, and run
> >    queue in a later time, we only hold the orphan_dir's lock
> >    during scanning.
> > 
> >  * Reflink create a oprhaned target in orphan_dir at the first
> >    step, and remove the targets and unset the flag at the third
> >    step, these two steps respectively hold the orphan_dir's lock
> >    themselves.
> > 
> > Based on above semantics, there is a possibility that a reflink
> > inode can be moved out of the orphan dir and have its ORPHANED_FL
> > cleared before the queue is run, which leads to a ERROR in
> > ocfs2_query_wipde_inode().
> > 
> > This patch helps to judge if a orphan inode to be wiped off, which
> > has NO ORPHANED_FL, is a legal alive reflinked target or not.
> > 
> > The patch also works for failed reflinked targets from a crash or
> > other failures during the reflink operation, they can be wiped off
> > as desired since these failed reflinked inodes always has ORPHANED_FL
> > set ondisk.
> 
> How is this? Wouldn't the failed reflink still have OCFS2_HAS_REFCOUNT_FL
> set as well as OCFS2_ORPHANED_FL? In the code below, we (correctly) skip
> those for delete.

	A failed reflink indeed has ORPHANED_FL.  Thus the if block is
skipped and we continue to the rest of the query_wipe checks.

Joel

-- 

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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127