linux-kernel - [PATCH] mtip32xx: Correctly handle bio->bi

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Date:	Tue, 14 May 2013 15:32:02 -0700
From:	Sam Bradshaw <sbradshaw@...ron.com>
To:	<axboe@...nel.dk>
CC:	<linux-kernel@...r.kernel.org>, <asamymuthupa@...ron.com>,
	<sbradshaw@...ron.com>
Subject: [PATCH] mtip32xx: Correctly handle bio->bi_idx != 0 conditions


Stacking drivers may append bvecs to existing bio's, resulting
in non-zero bi_idx conditions.  This patch counts the loops of
bio_for_each_segment() rather than inheriting the bi_idx value
to pass as a segment count to the hardware submission routine.

Signed-off-by: Sam Bradshaw <sbradshaw@...ron.com>
---
diff --git a/drivers/block/mtip32xx/mtip32xx.c
b/drivers/block/mtip32xx/mtip32xx.c
index 847107e..7c77ae1 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -3863,7 +3863,7 @@ static void mtip_make_request(struct request_queue
*queue, struct bio *bio)
 	struct driver_data *dd = queue->queuedata;
 	struct scatterlist *sg;
 	struct bio_vec *bvec;
-	int nents = 0;
+	int i, nents = 0;
 	int tag = 0, unaligned = 0;

 	if (unlikely(dd->dd_flag & MTIP_DDF_STOP_IO)) {
@@ -3921,11 +3921,12 @@ static void mtip_make_request(struct
request_queue *queue, struct bio *bio)
 		}

 		/* Create the scatter list for this bio. */
-		bio_for_each_segment(bvec, bio, nents) {
+		bio_for_each_segment(bvec, bio, i) {
 			sg_set_page(&sg[nents],
 					bvec->bv_page,
 					bvec->bv_len,
 					bvec->bv_offset);
+			nents++;
 		}

 		/* Issue the read/write. */
--
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