block: deprecate barrier and replace blk_queue_ordered() with blk_queue_flush()

Barrier is deemed too heavy and will soon be replaced by FLUSH/FUA
requests.  Deprecate barrier.  All REQ_HARDBARRIERs are failed with
-EOPNOTSUPP and blk_queue_ordered() is replaced with simpler
blk_queue_flush().

blk_queue_flush() takes combinations of REQ_FLUSH and FUA.  If a
device has write cache and can flush it, it should set REQ_FLUSH.  If
the device can handle FUA writes, it should also set REQ_FUA.

All blk_queue_ordered() users are converted.

* ORDERED_DRAIN is mapped to 0 which is the default value.
* ORDERED_DRAIN_FLUSH is mapped to REQ_FLUSH.
* ORDERED_DRAIN_FLUSH_FUA is mapped to REQ_FLUSH | REQ_FUA.

Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Boaz Harrosh <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: Chris Wright <[email protected]>
Cc: FUJITA Tomonori <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Alasdair G Kergon <[email protected]>
Cc: Pierre Ossman <[email protected]>
Cc: Stefan Weinhuber <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Tejun Heo 2010-09-03 11:56:16 +02:00 • committed by Jens Axboe
commit 4913efe456
15 changed files with 67 additions and 102 deletions

View file

@ -794,6 +794,26 @@ void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
}
EXPORT_SYMBOL(blk_queue_update_dma_alignment);
/**
* blk_queue_flush - configure queue's cache flush capability
* @q: the request queue for the device
* @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA
*
* Tell block layer cache flush capability of @q. If it supports
* flushing, REQ_FLUSH should be set. If it supports bypassing
* write cache for individual writes, REQ_FUA should be set.
*/
void blk_queue_flush(struct request_queue *q, unsigned int flush)
{
WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA));
if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA)))
flush &= ~REQ_FUA;
q->flush_flags = flush & (REQ_FLUSH | REQ_FUA);
}
EXPORT_SYMBOL_GPL(blk_queue_flush);
static int __init blk_settings_init(void)
{
blk_max_low_pfn = max_low_pfn - 1;