linux-kernel - Re: [PATCH 2/3] xen/blkback: Fix the inhibition to map pages when discarding sector ranges.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKH3R4-HJZBE-yWk=Dwkuwy13z1vdUrgEoJ9zFhTJgXgYfHHfA@mail.gmail.com>
Date:	Tue, 11 Oct 2011 15:33:11 +0800
From:	Li Dongyang <lidongyang@...ell.com>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Dong Yang Li <lidongyang@...e.com>, hch@...radead.org,
	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] xen/blkback: Fix the inhibition to map pages when
 discarding sector ranges.

On Tue, Oct 11, 2011 at 3:25 PM, Jan Beulich <JBeulich@...e.com> wrote:
>>>> On 10.10.11 at 17:28, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> wrote:
>> The 'operation' parameters are the ones provided to the bio layer while
>> the req->operation are the ones passed in between the backend and
>> frontend. We used the wrong 'operation' value to squash the
>> call to map pages when processing the discard operation resulting
>> in mapping the pages unnecessarily.
>>
>> CC: Li Dongyang <lidongyang@...ell.com>
>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
>> ---
>>  drivers/block/xen-blkback/blkback.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/block/xen-blkback/blkback.c
>> b/drivers/block/xen-blkback/blkback.c
>> index 184b133..3da9a40 100644
>> --- a/drivers/block/xen-blkback/blkback.c
>> +++ b/drivers/block/xen-blkback/blkback.c
>> @@ -707,7 +707,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
>>        * the hypercall to unmap the grants - that is all done in
>>        * xen_blkbk_unmap.
>>        */
>> -     if (operation != BLKIF_OP_DISCARD &&
>> +     if (operation != REQ_DISCARD &&
>
> Why is that check necessary in the first place? xen_blkbk_map() doesn't
> do any harm when req->nr_segments is zero (as could also be the case
> on WRITE_FLUSH ones).
>
Ah, you are right, we could remove this check then, Thanks
> Jan
>
>>                       xen_blkbk_map(req, pending_req, seg))
>>               goto fail_flush;
>>
>
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/