block: replace end_request() with [__]blk_end_request_cur()

end_request() has been kept around for backward compatibility;
however, it's about time for it to go away.

* There aren't too many users left.

* Its use of @updtodate is pretty confusing.

* In some cases, newer code ends up using mixture of end_request() and
  [__]blk_end_request[_all](), which is way too confusing.

So, add [__]blk_end_request_cur() and replace end_request() with it.
Most conversions are straightforward.  Noteworthy ones are...

* paride/pcd: next_request() updated to take 0/-errno instead of 1/0.

* paride/pf: pf_end_request() and next_request() updated to take
  0/-errno instead of 1/0.

* xd: xd_readwrite() updated to return 0/-errno instead of 1/0.

* mtd/mtd_blkdevs: blktrans_discard_request() updated to return
  0/-errno instead of 1/0.  Unnecessary local variable res
  initialization removed from mtd_blktrans_thread().

[ Impact: cleanup ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Joerg Dorchain <joerg@dorchain.net>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Laurent Vivier <Laurent@lvivier.info>
Cc: Tim Waugh <tim@cyberelk.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Markus Lidel <Markus.Lidel@shadowconnect.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: unsik Kim <donari75@gmail.com>
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index a49a9c8..76c4c8d 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -54,33 +54,33 @@
 
 	if (req->cmd_type == REQ_TYPE_LINUX_BLOCK &&
 	    req->cmd[0] == REQ_LB_OP_DISCARD)
-		return !tr->discard(dev, block, nsect);
+		return tr->discard(dev, block, nsect);
 
 	if (!blk_fs_request(req))
-		return 0;
+		return -EIO;
 
 	if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
-		return 0;
+		return -EIO;
 
 	switch(rq_data_dir(req)) {
 	case READ:
 		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 			if (tr->readsect(dev, block, buf))
-				return 0;
-		return 1;
+				return -EIO;
+		return 0;
 
 	case WRITE:
 		if (!tr->writesect)
-			return 0;
+			return -EIO;
 
 		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
 			if (tr->writesect(dev, block, buf))
-				return 0;
-		return 1;
+				return -EIO;
+		return 0;
 
 	default:
 		printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
-		return 0;
+		return -EIO;
 	}
 }
 
@@ -96,7 +96,7 @@
 	while (!kthread_should_stop()) {
 		struct request *req;
 		struct mtd_blktrans_dev *dev;
-		int res = 0;
+		int res;
 
 		req = elv_next_request(rq);
 
@@ -119,7 +119,7 @@
 
 		spin_lock_irq(rq->queue_lock);
 
-		end_request(req, res);
+		__blk_end_request_cur(req, res);
 	}
 	spin_unlock_irq(rq->queue_lock);