From: Mike Christie <michaelc@cs.wisc.edu>
To: dgilbert@interlog.com
Cc: SCSI development list <linux-scsi@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
James Bottomley <JBottomley@parallels.com>,
openosd@gmail.com
Subject: Re: [PATCH v2] sg: add SG_FLAG_Q_AT_TAIL flag
Date: Wed, 11 Jun 2014 16:14:58 -0500 [thread overview]
Message-ID: <5398C6D2.2020404@cs.wisc.edu> (raw)
In-Reply-To: <538F3416.5090306@interlog.com>
On 06/04/2014 09:58 AM, Douglas Gilbert wrote:
> When the SG_IO ioctl was copied into the block layer and
> later into the bsg driver, subtle differences emerged.
>
> One difference is the way injected commands are queued through
> the block layer (i.e. this is not SCSI device queueing nor SATA
> NCQ). Summarizing:
> - SG_IO in the block layer: blk_exec*(at_head=false)
> - sg SG_IO: at_head=true
> - bsg SG_IO: at_head=true
>
> Some time ago Boaz Harrosh introduced a sg v4 flag called
> BSG_FLAG_Q_AT_TAIL to override the bsg driver default.
> This patch does the equivalent for the sg driver.
>
>
> ChangeLog:
> Introduce SG_FLAG_Q_AT_TAIL flag to cause commands
> to be injected into the block layer with
> at_head=false.
>
> Changes since v1:
> Make guard condition (only take sg v3 interface or later
> invocations) clearer.
>
> Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Looks ok to me.
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
prev parent reply other threads:[~2014-06-11 21:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-04 14:58 [PATCH v2] sg: add SG_FLAG_Q_AT_TAIL flag Douglas Gilbert
2014-06-05 9:24 ` Christoph Hellwig
2014-06-05 15:27 ` Boaz Harrosh
2014-06-05 17:16 ` Jeremy Linton
2014-06-05 22:09 ` Douglas Gilbert
2014-06-11 14:54 ` Ewan Milne
2014-06-11 21:14 ` Mike Christie [this message]
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