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sg_ring: Gentler scsi merge

Rusty Russell linux-scsi 1 version In review

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  1. v1 Latest0 of 2 patches 1 replyIn review

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None of the 2 patches the cover letter announces are in this archive.

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Cover letter [PATCH 0/2] sg_ring: Gentler scsi merge

OK, after wading through many scsi drivers, I decided to change tack and try to provide a transition path. This is in two stages:

1) These two patches. sg_ring used underneath, but if any driver asks for scsi_sglist() they get a 2.6.24-style chained sg. No other patches are necessary.

2) Once all chained-sg-needing scsi drivers change to use cmd->sg (ie. sg_ring) directly, and the chained sg patches can be reverted. scsi_sglist() and scsi_sg_count() then become:

	/* You should only use these if you never need chained sgs */
	static inline struct scatterlist *scsi_sglist(struct scsi_cmd *cmd)
	{
		BUG_ON(!list_empty(&cmd->sg->list));
		return &cmd->sg->sg[0];
	}

	static unsigned int scsi_sg_count(struct scsi_cmd *cmd)
	{
		if (!cmd->sg)
			return 0;
		BUG_ON(!list_empty(&cmd->sg->list));
		return cmd->sg->num;
	}

Thanks,
Rusty.

Read the cover letter in its thread