Luben Tuikov wrote:
> --- James Bottomley <James.Bottomley@xxxxxxxxxxxx> wrote:
>> On Sat, 2006-11-04 at 11:54 -0800, Luben Tuikov wrote:
>>> Signed-off-by: Luben Tuikov <ltuikov@xxxxxxxxx>
>>> ---
>>> drivers/scsi/sd.c | 17 +++++++----------
>>> 1 files changed, 7 insertions(+), 10 deletions(-)
>>>
>>> This patch is 8 months old.
>> Um:
>>
>> patching file drivers/scsi/sd.c
>> Hunk #1 FAILED at 1354.
>> Hunk #2 FAILED at 1382.
>> 2 out of 2 hunks FAILED -- saving rejects to file drivers/scsi/sd.c.rej
>>
>> I think the code you're trying to change has altered a bit in the latest
>> kernels.
>
> Re-based:
>
> Signed-off-by: Luben Tuikov <ltuikov@xxxxxxxxx>
>
> ---
> drivers/scsi/sd.c | 13 +++++++------
> 1 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 84ff203..ffbd021 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -1467,7 +1467,6 @@ sd_read_cache_type(struct scsi_disk *sdk
> res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr);
>
> if (scsi_status_is_good(res)) {
> - int ct = 0;
> int offset = data.header_length + data.block_descriptor_length;
>
> if (offset >= SD_BUF_SIZE - 2) {
> @@ -1496,11 +1495,13 @@ sd_read_cache_type(struct scsi_disk *sdk
> sdkp->DPOFUA = 0;
> }
>
> - ct = sdkp->RCD + 2*sdkp->WCE;
> -
> - printk(KERN_NOTICE "SCSI device %s: drive cache: %s%s\n",
> - diskname, sd_cache_types[ct],
> - sdkp->DPOFUA ? " w/ FUA" : "");
> + printk(KERN_NOTICE "SCSI device %s: "
> + "write cache: %s, read cache: %s, %s\n",
> + diskname,
> + sdkp->WCE ? "enabled" : "disabled",
> + sdkp->RCD ? "disabled" : "enabled",
> + sdkp->DPOFUA ? "supports DPO and FUA"
> + : "doesn't support DPO or FUA");
>
> return;
> }
The definition of the DPOFUA flag (in the block descriptor
returned by MODE SENSE for direct access devices) is a bit
fuzzy in practice. When I queried the t10 reflector a
member from a disk company said it should be interpreted as
... we support DPO and/or FUA.
I also noticed that one disk manufacturer's unit attention mode
page had a bit to disable FUA (force unit access). So you can
set the FUA bit (in a READ or WRITE), we will ignore it! The
associated note says that it improves performance :-)
Doug Gilbert
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