i2o: block IO errors on i2o disk

I2O subsystem has been broken in mainstream several months ago (after
2.6.18).  Commit 4aff5e23 from Jens
Axboe split struct request ->flags into two parts: cmd_type and
cmd_flags.

In i2o layer this patch has replaced flag REQ_SPECIAL by the according
cmd_type.  However i2o has used REQ_SPECIAL not as command type but as
driver-specific flag for the debug purposes.  As result all i2o requests
have type "special" now, are not processed to the hardware and fail with
I/O error:

   i2o/hda:<3>Buffer I/O error on device i2o/hda, logical block 0
  Buffer I/O error on device i2o/hda, logical block 0
  Buffer I/O error on device i2o/hda, logical block 0
   unable to read partition table
  block-osm: device added (TID: 207): i2o/hda

The following patch removes the extra debug checks without any drawbacks and
restores the normal driver's work.
Signed-off-by: Vasily Averin <vvs@sw.ru>
Acked-by: Markus Lidel <Markus.Lidel@shadowconnect.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
From: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/message/i2o/i2o_block.c

@@ -390,13 +390,6 @@ static int i2o_block_prep_req_fn(struct request_queue *q, struct request *req)
 		return BLKPREP_KILL;
 	}
 
-	/* request is already processed by us, so return */
-	if (blk_special_request(req)) {
-		osm_debug("REQ_SPECIAL already set!\n");
-		req->cmd_flags |= REQ_DONTPREP;
-		return BLKPREP_OK;
-	}
-
 	/* connect the i2o_block_request to the request */
 	if (!req->special) {
 		ireq = i2o_block_request_alloc();
@@ -408,11 +401,8 @@ static int i2o_block_prep_req_fn(struct request_queue *q, struct request *req)
 		ireq->i2o_blk_dev = i2o_blk_dev;
 		req->special = ireq;
 		ireq->req = req;
-	} else
-		ireq = req->special;
-
+	}
 	/* do not come back here */
-	req->cmd_type = REQ_TYPE_SPECIAL;
 	req->cmd_flags |= REQ_DONTPREP;
 
 	return BLKPREP_OK;