[Ocfs2-devel] [PATCH 2/2] ext4: Fix deadlock in journal_unmap_buffer()

[Theodore Ts'o]

On Sat, Dec 22, 2012 at 12:03:47AM +0100, Jan Kara wrote:
>   I should have commented on this in the changelog :).
> jbd2_journal_invalidatepage() gets called only for file pagecache pages.
> Because ocfs2 doesn't do data journalling it never sees buffers that are
> part of a transaction in jbd2_journal_invalidatepage() (similarly to ext4
> except for data=journal case). I'll send a patch to just stop calling
> jbd2_journal_invalidatepage() for ocfs2... But you are safe to merge this
> patch in the mean time.

Ok, so if ocfs2 never tries journalling data blocks, then buffer_jbd()
will always be NULL, which reduces jbd2_journal_invalidate() to be
equivalent in functionality to block_invalidatepage(), and so it will
never abort and return EBUSY.
  
Thanks for the explanation, I'll apply the patch.

						- Ted