From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH 2/3] sd: Reject optimal transfer length smaller than page size Date: Wed, 16 Dec 2015 19:55:10 -0500 Message-ID: <567207EE.5050508@interlog.com> References: <1450306433-20166-1-git-send-email-martin.petersen@oracle.com> <1450306433-20166-2-git-send-email-martin.petersen@oracle.com> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.infotech.no ([82.134.31.41]:49456 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755593AbbLQAzY (ORCPT ); Wed, 16 Dec 2015 19:55:24 -0500 In-Reply-To: <1450306433-20166-2-git-send-email-martin.petersen@oracle.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Martin K. Petersen" , linux-scsi@vger.kernel.org, linux-block@vger.kernel.org On 15-12-16 05:53 PM, Martin K. Petersen wrote: > Eryu Guan reported that loading scsi_debug would fail. This turned out > to be caused by scsi_debug reporting an optimal I/O size of 32KB which > is smaller than the 64KB page size on the PowerPC system in question. > > Add a check to ensure that we only use the device-reported OPTIMAL > TRANSFER LENGTH if it is bigger than or equal to the page cache size. > > Reported-by: Eryu Guan > Reported-by: Ming Lei > Signed-off-by: Martin K. Petersen > --- > drivers/scsi/sd.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 3d22fc3e3c1a..4e08d1cd704d 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -2885,10 +2885,13 @@ static int sd_revalidate_disk(struct gendisk *disk) > > /* > * Use the device's preferred I/O size for reads and writes > - * unless the reported value is unreasonably large (or garbage). > + * unless the reported value is unreasonably small, large, or > + * garbage. > */ > - if (sdkp->opt_xfer_blocks && sdkp->opt_xfer_blocks <= dev_max && > - sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS) > + if (sdkp->opt_xfer_blocks && > + sdkp->opt_xfer_blocks <= dev_max && > + sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS && > + sdkp->opt_xfer_blocks * sdp->sector_size >= PAGE_CACHE_SIZE) > rw_max = q->limits.io_opt = > logical_to_sectors(sdp, sdkp->opt_xfer_blocks); > else > and following that 'else' is: rw_max = BLK_DEF_MAX_SECTORS; and blkdev.h says: enum blk_default_limits { BLK_MAX_SEGMENTS = 128, BLK_SAFE_MAX_SECTORS = 255, BLK_DEF_MAX_SECTORS = 2560, BLK_MAX_SEGMENT_SIZE = 65536, BLK_SEG_BOUNDARY_MASK = 0xFFFFFFFFUL, }; Reviewed-by: Douglas Gilbert