[PATCH] catch error when completing bio pairs

[PATCH] catch error when completing bio pairs

[Mike Christie]

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A couple of drivers can sometimes fail the first
segments in a bio then requeue the rest of the request. In this
situation, if the last part of the bio completes successfully
bio_pair_end_* will miss that the beginging of the bio had
failed becuase they just return one when bi_size is not yet
zero. The attached patch moves the error value test before
the bi_size to catch the above case.

Mike Christie

[-- Attachment #2: biopair-err.patch --]
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--- linux-2.6.5-rc2/fs/bio.c	2004-03-22 22:44:28.000000000 -0800
+++ linux-2.6.5-rc2-ec/fs/bio.c	2004-03-22 23:00:18.000000000 -0800
@@ -701,11 +701,12 @@ static int bio_pair_end_1(struct bio * b
 {
 	struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
 
-	if (bi->bi_size)
-		return 1;
 	if (err)
 		bp->error = err;
 
+	if (bi->bi_size)
+		return 1;
+
 	bio_pair_release(bp);
 	return 0;
 }
@@ -714,11 +715,12 @@ static int bio_pair_end_2(struct bio * b
 {
 	struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
 
-	if (bi->bi_size)
-		return 1;
 	if (err)
 		bp->error = err;
 
+	if (bi->bi_size)
+		return 1;
+
 	bio_pair_release(bp);
 	return 0;
 }

Re: [PATCH] catch error when completing bio pairs

[Jens Axboe]

On Mon, Mar 22 2004, Mike Christie wrote:
> A couple of drivers can sometimes fail the first
> segments in a bio then requeue the rest of the request. In this
> situation, if the last part of the bio completes successfully
> bio_pair_end_* will miss that the beginging of the bio had
> failed becuase they just return one when bi_size is not yet
> zero. The attached patch moves the error value test before
> the bi_size to catch the above case.

Yup that's a bug, patch is correct.

-- 
Jens Axboe