Re: [PATCH v4 0/3] scsi: fix internal write cache issue on usb hdd.

[Namjae Jeon]

Hi Greg.

Would you check this patch-set ?

Thanks.

2012/6/14, Namjae Jeon <linkinjeon@xxxxxxxxx>:
> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>
> The numbers of USB HDDs(All USB HDD I checked) does not respond
> correctly to scsi mode sense command for retrieving the write cache
> page status. Even though write cache is enabled by default, due to
> scsi driver assume that cache is not enabled which in turn might lead
> to loss of data since data still will be in cache.
> This result that all filesystems is not stable on USB HDD when the
> device is unplugged abruptly, even though these are having journaling
> feature. Our first trying is that scsi driver send ATA command
> (ATA Pass through, #58) to USB HDD after failure from normal routine to
> know write cache enable.
> We have known it is dangerous after testing several USB HDD. some of
> HDD is stalled by this command(A-DATA HDD). So we tried to make the
> patch James's suggestion(usb quirk) on version 2 that add product ID
> and verdor ID of USB HDD to USB quirk list after checking write cache.
> All filesystem will be stable on USB HDD registered in quirk list.
> And it will be updated continuously.
>
> 	scsi: set to WCE if usb cache quirk is present.
> 	usb: storage: add support for write cache quirk on usb hdd.
> 	usb: storage: update usb devices for write cache quirk in quirk.
>
>  drivers/scsi/sd.c          |    9 +++++++--
>  include/scsi/scsi_device.h |    1 +
>  drivers/usb/storage/scsiglue.c |    5 +++++
>  drivers/usb/storage/usb.c      |    5 ++++-
>  include/linux/usb_usual.h      |    4 +++-
>  drivers/usb/storage/unusual_devs.h |   24 ++++++++++++++++++++++++
>  Documentation/kernel-parameters.txt |    2 ++
>  7 files changed, 46 insertions(+), 4 deletions(-)
> --
> 1.7.9.5
>
>
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