On 2010-09-29 10:29, Chris Frey wrote:
> On Wed, Sep 29, 2010 at 08:10:06AM +0900, Jens Axboe wrote:
>> It looks like that if we need to restart the requeue, then
>> we use the initial position and not the current index. Does
>> this help?
>>
>> diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
>> index 1bcd208..81ee063 100644
>> --- a/arch/um/drivers/ubd_kern.c
>> +++ b/arch/um/drivers/ubd_kern.c
>> @@ -162,7 +162,7 @@ struct ubd {
>> spinlock_t lock;
>> struct scatterlist sg[MAX_SG];
>> struct request *request;
>> - int start_sg, end_sg;
>> + int start_sg, end_sg, rq_off;
>> };
>>
>> #define DEFAULT_COW { \
>> @@ -187,6 +187,7 @@ struct ubd {
>> .request = NULL, \
>> .start_sg = 0, \
>> .end_sg = 0, \
>> + .rq_off = 0, \
>> }
>>
>> /* Protected by ubd_lock */
>> @@ -1241,10 +1242,11 @@ static void do_ubd_request(struct request_queue *q)
>> dev->request = req;
>> dev->start_sg = 0;
>> dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
>> + dev->rq_off = 0;
>> }
>>
>> req = dev->request;
>> - sector = blk_rq_pos(req);
>> + sector = blk_rq_pos(req) + dev->rq_off;
>> while(dev->start_sg < dev->end_sg){
>> struct scatterlist *sg = &dev->sg[dev->start_sg];
>>
>> @@ -1273,6 +1275,7 @@ static void do_ubd_request(struct request_queue *q)
>> }
>>
>> dev->start_sg++;
>> + dev->rq_off += sg->length >> 9;
>> }
>> dev->end_sg = 0;
>> dev->request = NULL;
>>
>> --
>
> This patch does not fix the corruption issue for me. I applied the patch
> to 2.6.35.5, and reproduced the "deleted inode referenced" errors
> in both a gentoo and ubuntu guest OS. It does take longer to reproduce
> though, with this patch.
This seems to imply that the original commit pin pointed is not
the only issue we have in that code atm.
I think we need to find the real fix here, just disabling merging
is not a fix (it's just a nasty work-around for the real bug).
--
Jens Axboe
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