Re: [RFC 1/2] scsi core: alloc_cmnd

[Matthew Wilcox <matthew@wil.cx>]

On Tue, Oct 23, 2007 at 08:46:52PM +0200, Boaz Harrosh wrote:
> > We could also add an alloc_bidi_cmnd/destroy_bidi_cmnd to the shost
> > template.  Presumably most commands won't be bidi for any given host,
> > so it'd be a waste of space to allocate them for all commands.
> 
> Well no one really knows. The OSD scsi devices I use are bidi only commands
> (OK not only, 99%). The rest are not yet defined. (Like raid arrays that do 
> write-return-XOR)

What's the usage scenario though?  Do we envisage one scsi_host being
dedicated to OSD, or do we envisage OSDs being one component on a FC
network?  I suspect the latter, which leads me to want to do something
like ...

struct qla_cmnd {
	char *sp;
	unsigned int compl_status;
	unsigned int resid_len;
	unsigned int scsi_status;
	unsigned int actual_snslen;
	unsigned int entry_status;
}

struct qla_bidi_cmnd {
	struct bidi_cmnd;
	struct qla_cmnd;
}

struct qla_cmnd {
	struct scsi_cmnd;
	struct qla_cmnd;
}

But then this requires us to have a bidi_queue_command.  That might not
be such a bad idea anyway ...

-- 
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"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
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