From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Amit Sahrawat <amit.sahrawat83@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Douglas Gilbert <dgilbert@interlog.com>,
linux-usb@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>
Subject: Re: Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_type)
Date: Wed, 05 Oct 2011 13:08:15 -0700 [thread overview]
Message-ID: <1317845295.7238.15.camel@dabdike> (raw)
In-Reply-To: <CADDb1s031VX65+G-Uq-12y4qWq98-OS6DKz7mUCo=8AQkVQVTQ@mail.gmail.com>
On Thu, 2011-10-06 at 01:21 +0530, Amit Sahrawat wrote:
> > The best we could probably offer is an interface to turn on the WCE bit
> > in software (technically, you can do this today
> > in /scsi/class/scsi_disk/<disk>/cache_type, it's just that it will try
> > to commit the change as a MODE_SELECT which will presumably fail).
> Thanks James, is this related with SCSI command MODE_SELECT? and this
> is to be passed when there is some failure?
> or simply doing an "echo <value>" to
> /scsi/class/scsi_disk/<disk>/cache_type? can you please elaborate a
> little
You tell me since you have the device. What that echo does is that it
does try to make the change permanent with a mode select ... that likely
won't work and the cache change only takes if the revalidated disk says
the write back has been enabled (which I really think it won't). So I
think you need an additional software bit to flip for the case where the
device lies.
James
next prev parent reply other threads:[~2011-10-05 20:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CADDb1s0ZnHzM72sDnFmRrM=GFJtxj5JkYUSPo6GdyQ_=7L2m9A@mail.gmail.com>
[not found] ` <CADDb1s0ZnHzM72sDnFmRrM=GFJtxj5JkYUSPo6GdyQ_=7L2m9A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-10-04 14:10 ` Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_type) Alan Stern
2011-10-04 15:34 ` Amit Sahrawat
[not found] ` <CADDb1s3sPxpfNi-OD=QvVT+JWO9kUeTAmb8ZGyN0YCuBKWd4rg@mail.gmail.com>
2011-10-05 14:17 ` Re: Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_ =?windows-1252?Q?type=29 Alan Stern
2011-10-05 15:17 ` James Bottomley
2011-10-05 16:59 ` Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_type) Amit Sahrawat
2011-10-05 17:24 ` James Bottomley
2011-10-05 19:51 ` Amit Sahrawat
2011-10-05 20:08 ` James Bottomley [this message]
2011-10-07 5:09 ` Amit Sahrawat
2011-10-07 14:09 ` Re: Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_ =?windows-1252?Q?type=29 Alan Stern
[not found] <CADDb1s2bVY04G1fZ=3KwCagZHm_dOmLPxsUBKven7=iBo_nU-g@mail.gmail.com>
[not found] ` <CADDb1s2bVY04G1fZ=3KwCagZHm_dOmLPxsUBKven7=iBo_nU-g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-10-03 14:25 ` Re: Re: BUG in kernel: Wrong Handling of USB HDD’s in scsiglue(slave_configure) and scsi/sd(sd_read_cache_type) Alan Stern
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