sd-fix-rw_max.patch

   1 From 6b7e9cde49691e04314342b7dce90c67ad567fcc Mon Sep 17 00:00:00 2001
   2 From: "Martin K. Petersen" <martin.petersen@oracle.com>
   3 Date: Thu, 12 May 2016 22:17:34 -0400
   4 Subject: sd: Fix rw_max for devices that report an optimal xfer size
   5
   6 For historic reasons, io_opt is in bytes and max_sectors in block layer
   7 sectors. This interface inconsistency is error prone and should be
   8 fixed. But for 4.4--4.7 let's make the unit difference explicit via a
   9 wrapper function.
  10
  11 Fixes: d0eb20a863ba ("sd: Optimal I/O size is in bytes, not sectors")
  12 Cc: stable@vger.kernel.org # 4.4+
  13 Reported-by: Fam Zheng <famz@redhat.com>
  14 Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
  15 Reviewed-by: Christoph Hellwig <hch@lst.de>
  16 Tested-by: Andrew Patterson <andrew.patterson@hpe.com>
  17 Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
  18 ---
  19  drivers/scsi/sd.c | 8 ++++----
  20  drivers/scsi/sd.h | 5 +++++
  21  2 files changed, 9 insertions(+), 4 deletions(-)
  22
  23 diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
  24 index f459dff..60bff78 100644
  25 --- a/drivers/scsi/sd.c
  26 +++ b/drivers/scsi/sd.c
  27 @@ -2867,10 +2867,10 @@ static int sd_revalidate_disk(struct gendisk *disk)
  28         if (sdkp->opt_xfer_blocks &&
  29             sdkp->opt_xfer_blocks <= dev_max &&
  30             sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
  31 -           sdkp->opt_xfer_blocks * sdp->sector_size >= PAGE_CACHE_SIZE)
  32 -               rw_max = q->limits.io_opt =
  33 -                       sdkp->opt_xfer_blocks * sdp->sector_size;
  34 -       else
  35 +           logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
  36 +               q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
  37 +               rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
  38 +       } else
  39                 rw_max = BLK_DEF_MAX_SECTORS;
  40
  41         /* Combine with controller limits */
  42 diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
  43 index 654630b..765a6f1 100644
  44 --- a/drivers/scsi/sd.h
  45 +++ b/drivers/scsi/sd.h
  46 @@ -151,6 +151,11 @@ static inline sector_t logical_to_sectors(struct scsi_device *sdev, sector_t blo
  47         return blocks << (ilog2(sdev->sector_size) - 9);
  48  }
  49
  50 +static inline unsigned int logical_to_bytes(struct scsi_device *sdev, sector_t blocks)
  51 +{
  52 +       return blocks * sdev->sector_size;
  53 +}
  54 +
  55  /*
  56   * A DIF-capable target device can be formatted with different
  57   * protection schemes.  Currently 0 through 3 are defined:
  58 --
  59 cgit v0.12
  60