Re: [PATCH Linux 2.6.12-rc5-mm1 04/06] blk: reimplement QUEUE_OREDERED_FLUSH

Tejun Heo
2005-05-29T09:55:10Z

On Sun, May 29, 2005 at 01:23:38PM +0900, Tejun Heo wrote:
> 04_blk_flush_reimplementation.patch
>
> Reimplement QUEUE_ORDERED_FLUSH.
>
> * Implementation is contained inside blk layer. Only
> prepare_flush_fn() is needed from individual drivers.
> * Tagged queues which don't support ordered tag can use
> flushing.
> * Multi-bio barrier requests supported.
>
> Signed-off-by: Tejun Heo <htejun@gmail.com>
>
> drivers/block/elevator.c | 52 ++++----
> drivers/block/ll_rw_blk.c | 279 +++++++++++++++++++++++++++------------------
> drivers/ide/ide-disk.c | 39 ------
> drivers/ide/ide-io.c | 5
> drivers/scsi/scsi_lib.c | 21 ---
> drivers/scsi/sd.c | 25 ----
> include/linux/blkdev.h | 29 ++--
> include/scsi/scsi_driver.h | 1
> 8 files changed, 210 insertions(+), 241 deletions(-)

In blk_do_barrier() above patch implements, when a barrier request is
terminated w/ -EOPNOTSUPP, the request is not dequeued. The following
patch fixes this. The fixed path is a very rare error path, so, for
reviewing, this patch doesn't make much difference. I'll use properly
regenerated patch on the next posting of this patchset.

diff -u blk-fixes/drivers/block/ll_rw_blk.c blk-fixes/drivers/block/ll_rw_blk.c
--- blk-fixes/drivers/block/ll_rw_blk.c 2005-05-29 13:20:31.000000000 +0900
+++ blk-fixes/drivers/block/ll_rw_blk.c 2005-05-29 18:23:05.000000000 +0900
@@ -352,6 +352,8 @@
struct request *rq = q->bar_rq;
struct bio *bio = q->bar_bio;

+ BUG_ON(!list_empty(&rq->queuelist));
+
q->flush_seq = QUEUE_FLUSH_NONE;
q->bar_rq = NULL;
q->bar_bio = NULL;
@@ -457,6 +459,7 @@
* This can happen when the queue switches to
* ORDERED_NONE while this request is on it.
*/
+ blkdev_dequeue_request(rq);
end_that_request_first(rq, -EOPNOTSUPP,
rq->hard_nr_sectors);
end_that_request_last(rq, -EOPNOTSUPP);