[lkml]   [2007]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [RFC][PATCH 10/14] In-kernel file copy between union mounted filesystems
    On Tue, May 22, 2007 at 08:35:17AM -0400, Shaya Potter wrote:
    > Bharata B Rao wrote:
    > >
    > >In case of regular files, when we copyup a file, we are actually preventing
    > >any writes to the lower layers (which we have designated as read only).
    > >
    > >Applying the same logic to devices, what do we achieve by copying them up ?
    > >How does it matter if we write to the device through a node in the upper
    > >layer or in the lower layer. Both the writes eventually do the same thing.
    > What happens if the lower layer is on a read only medium. But the top
    > layer is RW. Why can't one change permissions? In your model, one can't.
    > What happens if one wants to share a lower layer read-only (I'm doing
    > this with my research into uses of union file systems), one doesn't want
    > permission change in one use of the lower layer to affect any of the
    > other uses.

    Ok, makes sense. Thanks for the clarification.

    So looks like in addition to copyup on open (which is what we do currently)
    there is a case for doing copyups for other situations also.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-05-23 12:37    [W:0.040 / U:31.496 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site