I want to call generic_make_request to do i/o on block drivers. I'm
trying to figure out how to create buffer_head's to do i/o. I foung some
code in the jbd source that creates a buffer_head for synchronous i/o; I
want to do it asynchronously. I
want to see if there is some documentation on how to do this. Does any
one know of any documentation on this?
I think it would go something like this:
DoRead(unsigned long sector, unsinged numSectors, void* buffer)
{
struct page* newPage = virt_to_page(buffer);
unsigned int newOffset = virt_to_offset(buffer);
struct buffer_head* bh = get_unused_buffer_head(1);
bh->b_prev_free = 0;
bh->b_next_free = 0;
init_buffer(bh, driver_end_io, NULL /* ?? Context ?? */);
atomic_set(&bh->b_count, 1);
set_bh_page(bh, newPage, newOffset);
bh->b_size = numSectors; /* ?? bytes or sectors ?? */
bh->b_dev = MAKEDEV(major, minor);
bh->b_blocknr = sector;
bh->b_state |= (1 << BH_Mapped) | (1 << BH_Dirty);
generic_make_request(READ, bh);
}
I'm just guessing on this. Can anyone help me figure this out or refer me
to a good source?
Thanks
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