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    SubjectRe: Zero length files - an alternative approach?
    On Sun 2009-03-29 13:10:23, M?ns Rullg?rd wrote:
    > "Andreas T.Auer" <andreas.t.auer_lkml_73537@ursus.ath.cx> writes:
    >
    > > On 29.03.2009 13:22 M?ns Rullg?rd wrote:
    > >> Consider this scenario:
    > >>
    > >> 1. Create/write/close newfile
    > >> 2. Rename newfile to oldfile
    > >> 3. Open/read oldfile. This must return the new contents.
    > >> 4. System crash and reboot before delayed allocation/flush complete
    > >> 5. Open/read oldfile. Old contents now returned.
    > >>
    > >> This rollback isn't obviously, to me at least, without problems of its
    > >> own.
    > >>
    > > Having the old data in 5) is far better than having no data in 5).
    >
    > Of course having old data is better than no data. However, fsync()
    > and similar approaches make a rollback to old data after new data has
    > been visible impossible or far less likely than the suggested one.

    Untrue. Unless you fsync after rename, you can get olddata.

    fsync() is easy. But some people _want_ to have either newdata _or_
    olddata, but don't care which one, and would prefer to avoid
    fsync. That's where replace() should help...
    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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