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    SubjectRe: How does ext2 implement sparse files?
    On Feb 1, 2008 2:14 AM, Andi Kleen <> wrote:
    > Lars Noschinski <> writes:
    > > For an university project, we had to write a toy filesystem (ext2-like),
    > > for which I would like to implement sparse file support. For this, I
    > > digged through the ext2 source code; but I could not find the point,
    > > where ext2 detects holes.
    > >
    > > As far as I can see from fs/buffer.c, an hole is a buffer_head which is
    > > not mapped, but uptodate. But I cannot find a relevant source line,
    > > where ext2 makes usage of this information.
    > It does not explicitely detect holes; holey data is just never written
    > so no space for it is allocated.

    does anybody know how to make a hole in a large file which already has
    real content from user space application?
    In my project I need this function to delete a piece of content from
    an exist large effectively.

    > -Andi
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