O_DIRECT broken in 2.5.3-preX ?

From: Badari Pulavarty (pbadari@us.ibm.com)
Date: Thu Jan 24 2002 - 16:52:04 EST

Hi,

I am reading the O_DIRECT code patch for 2.5.3-pre4. I was wondering
how is this working in 2.5.X ? Here is my concern:

generic_direct_IO() creates a blocks[] list and passes it to
brw_kiovec() with a single kiobuf.
        
        retval = brw_kiovec(rw, 1, &iobuf, inode->i_dev, blocks, blocksize);

But brw_kiovec() uses only b[0] to call ll_rw_bio().

        for (i = 0; i < nr; i++) {
                iobuf = iovec[i];
                iobuf->errno = 0;

                ll_rw_kio(rw, iobuf, dev, b[i] * (size >> 9));
        }

Note that nr = 1 here. ll_rw_kio() uses b[0] as starting sector
and does the entire IO (for iobuf->length). This is wrong !!!
It is doing IO from wrong blocks. Some one should use other
block numbers from blocks[] list. Isn't it ?

What am I missing here ? Please let me know.

Thanks,
Badari
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