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/block/xd.c b/drivers/block/xd.c
index 64b496f..6f6ad82 100644
--- a/drivers/block/xd.c
+++ b/drivers/block/xd.c
@@ -314,21 +314,22 @@
 		int retry;
 
 		if (!blk_fs_request(req)) {
-			end_request(req, 0);
+			__blk_end_request_cur(req, -EIO);
 			continue;
 		}
 		if (block + count > get_capacity(req->rq_disk)) {
-			end_request(req, 0);
+			__blk_end_request_cur(req, -EIO);
 			continue;
 		}
 		if (rw != READ && rw != WRITE) {
 			printk("do_xd_request: unknown request\n");
-			end_request(req, 0);
+			__blk_end_request_cur(req, -EIO);
 			continue;
 		}
 		for (retry = 0; (retry < XD_RETRIES) && !res; retry++)
 			res = xd_readwrite(rw, disk, req->buffer, block, count);
-		end_request(req, res);	/* wrap up, 0 = fail, 1 = success */
+		/* wrap up, 0 = success, -errno = fail */
+		__blk_end_request_cur(req, res);
 	}
 }
 
@@ -418,7 +419,7 @@
 				printk("xd%c: %s timeout, recalibrating drive\n",'a'+drive,(operation == READ ? "read" : "write"));
 				xd_recalibrate(drive);
 				spin_lock_irq(&xd_lock);
-				return (0);
+				return -EIO;
 			case 2:
 				if (sense[0] & 0x30) {
 					printk("xd%c: %s - ",'a'+drive,(operation == READ ? "reading" : "writing"));
@@ -439,7 +440,7 @@
 				else
 					printk(" - no valid disk address\n");
 				spin_lock_irq(&xd_lock);
-				return (0);
+				return -EIO;
 		}
 		if (xd_dma_buffer)
 			for (i=0; i < (temp * 0x200); i++)
@@ -448,7 +449,7 @@
 		count -= temp, buffer += temp * 0x200, block += temp;
 	}
 	spin_lock_irq(&xd_lock);
-	return (1);
+	return 0;
 }
 
 /* xd_recalibrate: recalibrate a given drive and reset controller if necessary */