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    SubjectRe: [PATCH 07/38] whiteout: Set S_OPAQUE inode flag when creating directories
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    On Fri, 2010-07-16 at 16:12 -0400, Valerie Aurora wrote:
    > On Tue, Jul 13, 2010 at 12:05:56PM +0800, Ian Kent wrote:
    > > On Tue, Jun 15, 2010 at 11:39:37AM -0700, Valerie Aurora wrote:
    > > > From: Jan Blunck <jblunck@suse.de>
    > > >
    > > > In case of an union directory we don't want that the directories on lower
    > > > layers of the union "show through". So to prevent that the contents of
    > > > underlying directories magically shows up after a mkdir() we set the S_OPAQUE
    > > > flag if directories are created where a whiteout existed before.
    > >
    > > I found this hard to understand.
    > >
    > > Do you mean:
    > >
    > > For directories within a union that are whiteouts we don't want the entries of
    > > lower layer file system to "show through". To achieve this we set the S_OPAQUE
    > > flag after a mkdir() on directories that are whiteouts.
    >
    > That is much clearer. I ended up with this version, what do you think?
    >
    > whiteout: Set opaque flag if new directory was previously a whiteout
    >
    > If we mkdir() a directory on the top layer of a union, we don't want
    > entries from a matching directory on the lower layer to "show through"
    > suddenly. To prevent this, we set the opaque flag on a directory if
    > there was previously a white-out with the same name. (If there is no
    > white-out and the directory exists in a lower layer, then mkdir() will
    > fail with EEXIST.)

    That's much clearer IMHO.

    >
    > -VAL




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