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    Subject[PATCH 4.14 097/183] scsi: sd: Optimal I/O size should be a multiple of physical block size
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Martin K. Petersen <martin.petersen@oracle.com>

    commit a83da8a4509d3ebfe03bb7fffce022e4d5d4764f upstream.

    It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
    0xFFFF blocks. That looks bogus, especially for a device with a
    4096-byte physical block size.

    Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
    reported physical block size.

    To make the sanity checking conditionals more readable--and to
    facilitate printing warnings--relocate the checking to a helper
    function. No functional change aside from the printks.

    Cc: <stable@vger.kernel.org>
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
    Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/scsi/sd.c | 59 +++++++++++++++++++++++++++++++++++++++++++++---------
    1 file changed, 50 insertions(+), 9 deletions(-)

    --- a/drivers/scsi/sd.c
    +++ b/drivers/scsi/sd.c
    @@ -3077,6 +3077,55 @@ static void sd_read_security(struct scsi
    sdkp->security = 1;
    }

    +/*
    + * Determine the device's preferred I/O size for reads and writes
    + * unless the reported value is unreasonably small, large, not a
    + * multiple of the physical block size, or simply garbage.
    + */
    +static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
    + unsigned int dev_max)
    +{
    + struct scsi_device *sdp = sdkp->device;
    + unsigned int opt_xfer_bytes =
    + logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
    +
    + if (sdkp->opt_xfer_blocks > dev_max) {
    + sd_first_printk(KERN_WARNING, sdkp,
    + "Optimal transfer size %u logical blocks " \
    + "> dev_max (%u logical blocks)\n",
    + sdkp->opt_xfer_blocks, dev_max);
    + return false;
    + }
    +
    + if (sdkp->opt_xfer_blocks > SD_DEF_XFER_BLOCKS) {
    + sd_first_printk(KERN_WARNING, sdkp,
    + "Optimal transfer size %u logical blocks " \
    + "> sd driver limit (%u logical blocks)\n",
    + sdkp->opt_xfer_blocks, SD_DEF_XFER_BLOCKS);
    + return false;
    + }
    +
    + if (opt_xfer_bytes < PAGE_SIZE) {
    + sd_first_printk(KERN_WARNING, sdkp,
    + "Optimal transfer size %u bytes < " \
    + "PAGE_SIZE (%u bytes)\n",
    + opt_xfer_bytes, (unsigned int)PAGE_SIZE);
    + return false;
    + }
    +
    + if (opt_xfer_bytes & (sdkp->physical_block_size - 1)) {
    + sd_first_printk(KERN_WARNING, sdkp,
    + "Optimal transfer size %u bytes not a " \
    + "multiple of physical block size (%u bytes)\n",
    + opt_xfer_bytes, sdkp->physical_block_size);
    + return false;
    + }
    +
    + sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",
    + opt_xfer_bytes);
    + return true;
    +}
    +
    /**
    * sd_revalidate_disk - called the first time a new disk is seen,
    * performs disk spin up, read_capacity, etc.
    @@ -3146,15 +3195,7 @@ static int sd_revalidate_disk(struct gen
    dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
    q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);

    - /*
    - * Determine the device's preferred I/O size for reads and writes
    - * 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 &&
    - logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
    + if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
    q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
    rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
    } else

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