From 9934c8c04561413609d2bc38c6b9f268cba774a4 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 8 May 2009 11:54:16 +0900 Subject: block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo Cc: Rusty Russell Cc: James Bottomley Cc: Mike Miller Cc: unsik Kim Cc: Paul Clements Cc: Tim Waugh Cc: Geert Uytterhoeven Cc: David S. Miller Cc: Laurent Vivier Cc: Jeff Garzik Cc: Jeremy Fitzhardinge Cc: Grant Likely Cc: Adrian McMenamin Cc: Stephen Rothwell Cc: Bartlomiej Zolnierkiewicz Cc: Borislav Petkov Cc: Sergei Shtylyov Cc: Alex Dubov Cc: Pierre Ossman Cc: David Woodhouse Cc: Markus Lidel Cc: Stefan Weinhuber Cc: Martin Schwidefsky Cc: Pete Zaitcev Cc: FUJITA Tomonori Signed-off-by: Jens Axboe --- drivers/block/paride/pcd.c | 3 +-- drivers/block/paride/pd.c | 7 ++----- drivers/block/paride/pf.c | 3 +-- 3 files changed, 4 insertions(+), 9 deletions(-) (limited to 'drivers/block/paride') diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c index 425f81586a31..911dfd98d813 100644 --- a/drivers/block/paride/pcd.c +++ b/drivers/block/paride/pcd.c @@ -720,10 +720,9 @@ static void do_pcd_request(struct request_queue * q) return; while (1) { if (!pcd_req) { - pcd_req = elv_next_request(q); + pcd_req = blk_fetch_request(q); if (!pcd_req) return; - blkdev_dequeue_request(pcd_req); } if (rq_data_dir(pcd_req) == READ) { diff --git a/drivers/block/paride/pd.c b/drivers/block/paride/pd.c index d2ca3f552061..bf5955b3d873 100644 --- a/drivers/block/paride/pd.c +++ b/drivers/block/paride/pd.c @@ -412,11 +412,9 @@ static void run_fsm(void) spin_lock_irqsave(&pd_lock, saved_flags); if (!__blk_end_request_cur(pd_req, res == Ok ? 0 : -EIO)) { - pd_req = elv_next_request(pd_queue); + pd_req = blk_fetch_request(pd_queue); if (!pd_req) stop = 1; - else - blkdev_dequeue_request(pd_req); } spin_unlock_irqrestore(&pd_lock, saved_flags); if (stop) @@ -706,10 +704,9 @@ static void do_pd_request(struct request_queue * q) { if (pd_req) return; - pd_req = elv_next_request(q); + pd_req = blk_fetch_request(q); if (!pd_req) return; - blkdev_dequeue_request(pd_req); schedule_fsm(); } diff --git a/drivers/block/paride/pf.c b/drivers/block/paride/pf.c index d6f7bd84ed39..68a90834e993 100644 --- a/drivers/block/paride/pf.c +++ b/drivers/block/paride/pf.c @@ -762,10 +762,9 @@ static void do_pf_request(struct request_queue * q) return; repeat: if (!pf_req) { - pf_req = elv_next_request(q); + pf_req = blk_fetch_request(q); if (!pf_req) return; - blkdev_dequeue_request(pf_req); } pf_current = pf_req->rq_disk->private_data; -- cgit v1.2.3