Re: [Bug 12713] Hang on resume from hibernation, apparently as result of 213d9417fec

[Michael S. Tsirkin]

On Mon, Feb 16, 2009 at 9:27 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
> On Mon, Feb 16 2009, Michael S. Tsirkin wrote:
>> On Mon, Feb 16, 2009 at 2:05 AM, Michael S. Tsirkin
>> <m.s.tsirkin@xxxxxxxxx> wrote:
>> > Summary: seem to need to revert 213d9417fec62ef4c3675621b9364a667954d4dd
>> > to fix resume from hibernation. Bugzilla entry created:
>> > http://bugzilla.kernel.org/show_bug.cgi?id=12713
>>
>> Looking over this, I see something strange in the commit in question:
>>
>> diff --git a/include/linux/bio.h b/include/linux/bio.h
>> index 5175aa3..f53568c 100644
>> --- a/include/linux/bio.h
>> +++ b/include/linux/bio.h
>> @@ -163,12 +163,15 @@ struct bio {
>>  #define BIO_RW         0       /* Must match RW in req flags (blkdev.h) */
>>  #define BIO_RW_AHEAD   1       /* Must match FAILFAST in req flags */
>>  #define BIO_RW_BARRIER 2
>> -#define BIO_RW_SYNC    3
>> -#define BIO_RW_META    4
>> -#define BIO_RW_DISCARD 5
>> -#define BIO_RW_FAILFAST_DEV            6
>> -#define BIO_RW_FAILFAST_TRANSPORT      7
>> -#define BIO_RW_FAILFAST_DRIVER         8
>> +#define BIO_RW_SYNCIO  3
>> +#define BIO_RW_UNPLUG  4
>> +#define BIO_RW_META    5
>> +#define BIO_RW_DISCARD 6
>> +#define BIO_RW_FAILFAST_DEV            7
>> +#define BIO_RW_FAILFAST_TRANSPORT      8
>> +#define BIO_RW_FAILFAST_DRIVER         9
>> +
>> +#define BIO_RW_SYNC    (BIO_RW_SYNCIO | BIO_RW_UNPLUG)
>>
>>  /*
>>   * upper 16 bits of bi_rw define the io priority of this bio
>>
>> I haven't read the code in depth, but taking running numbers and doing
>> bitwise "or"
>> on them looks a bit strange to me.
>> So here BIO_RW_SYNC is (3 | 4) = 7, that is the same as BIO_RW_FAILFAST_DEV.
>> So for example bio_failfast_dev and bio_sync are the same.
>>
>> Jens, could you comment on this please? Is this intentional?
>
> That's clearly a braino, you can't OR the shift values of course. I'll
> get it fixed up asap!

Cool, send me a patch, I'll test.

> --
> Jens Axboe
>
>
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