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    SubjectZero length files - an alternative approach?
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    Just a thought on the ongoing discussion of dataloss with ext4 vs ext3.

    Taking the common scenario:
    Read oldfile
    create newfile file
    write newfile data
    close newfile
    rename newfile to oldfile

    When using this scenario, the application writer wants to ensure that
    either the old or new content are present. With delayed allocation, this
    can lead to zero length files. Most of the suggestions on how to address
    this have involved syncing the data either before the rename or making
    the rename sync the data.

    What about, instead of 'bringing forward' the allocation and flushing of
    the data, would it be possible to instead delay the rename until after
    the blocks for newfile have been allocated and the data buffers flushed?
    This would keep the performance benefits of delayed allocation etc and
    also satisfy the applications developers' apparent dislike of using
    fsync(). It would give better performance that syncing the data at
    rename time (either using fsync() or automatically) and satisfy the
    requirements that either the old or new content is present.

    I am not a filesystem developer, so do not know how feasible this would
    be.


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