linux-kernel - [PATCH] pktcdvd: don't rely on bio_init() preserving bio->bi

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Date:	Thu, 20 Sep 2007 23:25:32 +0200
From:	Laurent Riffard <laurent.riffard@...e.fr>
To:	Jens Axboe <jens.axboe@...cle.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Peter Osterlund <petero2@...ia.com>
Subject: [PATCH] pktcdvd: don't rely on bio_init() preserving bio->bi_destructor

Le 14.09.2007 21:04, Laurent Riffard a écrit :
> Le 14.09.2007 13:06, Jens Axboe a écrit :
>> On Fri, Sep 14 2007, Jens Axboe wrote:
>>> On Fri, Sep 14 2007, Laurent Riffard wrote:
>>>> Le 10.09.2007 22:19, Laurent Riffard a écrit :
>>>>> Jens,
>>>>>
>>>>> git-block.patch broke pktcdvd, I've got an Oops while syncing:
>>>>>
> [snip]
>>>> I dig through git-block.patch and the culprit seems to be commit
>>>> c94f1c4ac87862675c8d70941973bc3a69aff5d8 "bio: use memset() in
>>>> bio_init()".
>>>>
>>>> Maybe the real bug is a bad bio initialization in pktcdvd driver,
>>>> which is revealed by this commit ?
>>> At least pktcdvd doesn't expect bio->bi_io_vec[] to be cleared, that's
>>> why it's oopsing now. I'll revert this bit for now, thanks for the
>>> report.
>> Rethinking this, I think bio_init() is doing the right thing, only
>> pktcdvd seems to rely on it preserving some members. So I'd rather fixup
>> pktcdvd instead.
>>
>> Does this work for you?
> 
> Well, it's better: I was able to mount the DVD-RW, sync, and write data,
> but kernel oopsed when I unmounted the drive:

Jens,

this patch, applied on top of your previous patch, solved it.



pktcdvd: don't rely on bio_init() preserving bio->bi_destructor

Signed-off-by: Laurent Riffard <laurent.riffard@...e.fr>
---
 drivers/block/pktcdvd.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6-mm/drivers/block/pktcdvd.c
===================================================================
--- linux-2.6-mm.orig/drivers/block/pktcdvd.c
+++ linux-2.6-mm/drivers/block/pktcdvd.c
@@ -1156,6 +1156,7 @@ static void pkt_gather_data(struct pktcd
 		bio->bi_end_io = pkt_end_io_read;
 		bio->bi_private = pkt;
 		bio->bi_io_vec = vec;
+		bio->bi_destructor = pkt_bio_destructor;
 
 		p = (f * CD_FRAMESIZE) / PAGE_SIZE;
 		offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
@@ -1453,6 +1454,7 @@ static void pkt_start_write(struct pktcd
 	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
 	pkt->w_bio->bi_private = pkt;
 	pkt->w_bio->bi_io_vec = bvec;
+	pkt->w_bio->bi_destructor = pkt_bio_destructor;
 	for (f = 0; f < pkt->frames; f++)
 		if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset))
 			BUG();




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