On Wed, Sep 09, 2009 at 09:35:40PM -0400, Theodore Tso wrote:
> On Wed, Sep 09, 2009 at 05:07:28PM -0700, Curt Wohlgemuth wrote:
> >
> > First, ext4_journal_forget() is called from ext4_forget() only when
> > we're journalling; without a journal, ext4_journal_forget() is only
> > called for various non-extent paths. ext4_forget() could be changed,
> > of course...
>
> Ext4_forget() calls either ext4_journal_forget() or
> ext4_journal_revoke(). So we need to fix up both functions.
>
> - Ted
>
> commit 4afdf0958f6f7b878e6d85cb4e0c0c12a0bd74e2
> Author: Theodore Ts'o <tytso@xxxxxxx>
> Date: Wed Sep 9 21:32:41 2009 -0400
>
> ext4: Use bforget() in no journal mode for ext4_journal_{forget,revoke}()
>
> When ext4 is using a journal, a metadata block which is deallocated
> must be passed into the journal layer so it can be dropped from the
> current transaction and/or revoked. This is done by calling the
> functions ext4_journal_forget() and ext4_journal_revoke(), which call
> jbd2_journal_forget(), and jbd2_journal_revoke(), respectively.
>
> Since the jbd2_journal_forget() and jbd2_journal_revoke() call
> bforget(), if ext4 is not using a journal, ext4_journal_forget() and
> ext4_journal_revoke() must call bforget() to avoid a dirty metadata
> block overwriting a block after it has been reallocated and reused for
> another inode's data block.
>
I am sure i am missing something. But where are we adding the buffer_head
to the mapping->private_list ?. For ext2 when we allocate meta data blocks
we do mark_buffer_dirty_inode which add the buffer_head to the inodes
private_list. Shouldn't we do something similar with Ext4 without journal ?
-aneesh
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