[OpenAFS-devel] Bug in namei_ops.c

[Hartmut Reuter]

I have found a "nice" bug in namei_ops.c:

In GetFreeTag() the following code was used to find a free place in the
link table entry:

    /* Now find a free column in this row and claim it. */
    coldata = 0x7;
    for (col = 0; col<NAMEI_MAXVOLS; col++) {
        coldata <<= col * 3;
        if ((row & coldata) == 0)
            break;
    }

What happens? 
With col == 0 we look for the bits 0x7. This is ok.
With col == 1 we look for the bits 0x38. This is also ok.
With col == 2 we look for the bits 0xe00 instead of 0x1c0 !!!
But later the allocation is done correctly with 0x40.
Thus the next time he will find again a free place for col == 2 !
For higher values of col the test is also incorrect, of course.

Now how should look like:

    /* Now find a free column in this row and claim it. */
    for (col = 0; col<NAMEI_MAXVOLS; col++) {
        coldata = 7 << (col * 3);
        if ((row & coldata) == 0)
            break;
    }

Hartmut
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301 
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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