>>>>> "marcelo" == Marcelo Tosatti <marcelo@conectiva.com.br> writes:
marcelo> On Mon, 3 Jul 2000, Jens Axboe wrote:
>> On Sat, Jul 01 2000, Marcelo Tosatti wrote:
>> > Hi,
>> >
>> > This silly patch avoids that by making ll_rw_block() ignore the IO if the
>> > request queue is full, causing the process to search for more freeable
>> > pages instead blocking.
>> >
>> > --- fs/buffer.c.orig Sat Jul 1 20:49:19 2000
>> > +++ fs/buffer.c Sat Jul 1 20:28:36 2000
>> > @@ -1517,7 +1517,7 @@
>> > if (wait)
>> > __wait_on_buffer(p);
>> > } else if (buffer_dirty(p))
>> > - ll_rw_block(WRITE, 1, &p);
>> > + ll_rw_block(WRITEA, 1, &p);
>> > } while (tmp != bh);
>> >
>> > do {
>>
>> This is wrong -- if the buffer is not queued because we are out of
>> free request slots, it has still already been locked at this point
>> (and _Req).
marcelo> if (!req) {
marcelo> if (rw_ahead)
marcelo> goto end_io;
marcelo> req = __get_request_wait(max_req, bh->b_rdev);
marcelo> }
marcelo> In case we fail to find a free request, bh->b_end_io is called, and
marcelo> it unlocks the buffer.
Think what can happen if bh->b_end_io is set as _async handler, it
wolud unlock the buffer and more things that you don't want posibly
for it to do.
Later, Juan.
-- In theory, practice and theory are the same, but in practice they are different -- Larry McVoy- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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