Deadlocked kernel when using brw_kiovec to do direct I/O

[Hanson, Jonathan M]

	I'm using brw_kiovec() on a 2.4.28 kernel to write directly to a
hard drive from a kernel module that I wrote. I have a 64k buffer that I
pass to brw_kiovec() and it writes the data to the hard drive directly
like it's supposed to. However, I noticed that if I make more than one
call to brw_kiovec() to write more data, the second call will cause the
machine to freeze hard. I have to reboot via the reset button (SysRq
doesn't work). Below is the code from just the part that calls
brw_kiovec() (based on some of the code in the Linux Kernel Crash Dump):

void RC_file_writer(const char *buffer)
{
        int return_value, i;
        unsigned long *b = RC_dump_iobuf->blocks, blocknr, blocks;

        if (RC_dump_offset & (RC_dump_block_size - 1))
        {
                printk(KERN_ERR "RapidCapture: RC_dump_offset wasn't
aligned properly.\n");
                return;
        }

        /* Reset the block number values */
        blocknr = RC_dump_offset >> RC_dump_block_shift;


        /* Calculate the number of blocks */
        blocks = RC_BUFFER_SIZE >> RC_dump_block_shift;
        if (blocks > (KIO_MAX_SECTORS >> (RC_dump_block_shift - 9)))
                blocks = KIO_MAX_SECTORS >> (RC_dump_block_shift - 9);

        /* Map the block numbers */
        for (i = 0; i < blocks; i++)
                b[i] = blocknr++;

        /* Write the data to the raw device bypassing any file caches.
*/
        return_value = brw_kiovec(WRITE, 1, &RC_dump_iobuf,
RC_dump_device, b, RC_dump_block_size);
        if (return_value != RC_BUFFER_SIZE)
                printk(KERN_ERR "RapidCapture: Write was trucated!\n");
        else
                RC_dump_offset += return_value;
}
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