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    SubjectRe: CD writing in future Linux (stirring up a hornets' nest)
    On Fri, Feb 10, 2006 at 09:13:44AM -0600, Christopher Friesen wrote:
    > Joerg Schilling wrote:
    > >"Christopher Friesen" <cfriesen@nortel.com> wrote:
    >
    > >>There's nothing there that says the mapping cannot change with
    > >>time...just that it has to be unique.
    > >
    > >
    > >If it changes over the runtime of a program, it is not unique from the
    > >view of that program.
    >
    > That depends on what "uniquely identified" actually means.

    "The st_ino and st_dev fields taken together uniquely identify the
    file within the system."

    > One possible definition is that at any time, a particular path maps to a
    > single unique st_ino/st_dev tuple.

    The quoted sentence certainly implies _at_least_ that much.

    > The other possibility (and this is what you seem to be advocating) is
    > that a st_ino/st_dev tuple always maps to the same file over the entire
    > runtime of the system.

    However, I don't think this is a reasonable interpretation, and it's
    clearly _not_ the one that Joerg is implying.

    Joerg is claiming that the quoted sentence also implies that
    _different_ st_ino/st_dev pairs will _always_ identify different
    files. Taken in just the immediate context of stat.h, this is a
    very reasonable interpretation.

    > This second possibility seems easily disproved. If you delete and
    > recreate files on a filesystem (assuming nobody has open files in the
    > filesystem), at some point a new file will end up with the same inode as
    > an old (deleted) file. The two files are different, but have the same
    > st_ino/st_dev tuple.
    >
    > This leaves the first possibility as the only choice...

    If you want to show that his interpretation is incorrent (which it
    may be for all I know), you need a better argument than this.

    -chris

    >
    > Chris
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