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Commit 824d7b57 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by James Bottomley
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[SCSI] scsi_lib: add scatter/gather data buffer accessors 



This adds a set of accessors for the scsi data buffer. This is in
preparation for chaining sg lists and bidirectional requests (and
possibly, the mid-layer dma mapping).

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 9ef3e4a4

drivers/scsi/scsi_lib.c

+38 −0
Original line number Diff line number Diff line
@@ -2290,3 +2290,41 @@ void scsi_kunmap_atomic_sg(void *virt) 
	kunmap_atomic(virt, KM_BIO_SRC_IRQ);

}

EXPORT_SYMBOL(scsi_kunmap_atomic_sg);



/**

 * scsi_dma_map - perform DMA mapping against command's sg lists

 * @cmd:	scsi command

 *

 * Returns the number of sg lists actually used, zero if the sg lists

 * is NULL, or -ENOMEM if the mapping failed.

 */

int scsi_dma_map(struct scsi_cmnd *cmd)

{

	int nseg = 0;



	if (scsi_sg_count(cmd)) {

		struct device *dev = cmd->device->host->shost_gendev.parent;



		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),

				  cmd->sc_data_direction);

		if (unlikely(!nseg))

			return -ENOMEM;

	}

	return nseg;

}

EXPORT_SYMBOL(scsi_dma_map);



/**

 * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map

 * @cmd:	scsi command

 */

void scsi_dma_unmap(struct scsi_cmnd *cmd)

{

	if (scsi_sg_count(cmd)) {

		struct device *dev = cmd->device->host->shost_gendev.parent;



		dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),

			     cmd->sc_data_direction);

	}

}

EXPORT_SYMBOL(scsi_dma_unmap);

include/scsi/scsi_cmnd.h

+20 −0
Original line number Diff line number Diff line
@@ -135,4 +135,24 @@ extern void scsi_kunmap_atomic_sg(void *virt); 
extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);

extern void scsi_free_sgtable(struct scatterlist *, int);



extern int scsi_dma_map(struct scsi_cmnd *cmd);

extern void scsi_dma_unmap(struct scsi_cmnd *cmd);



#define scsi_sg_count(cmd) ((cmd)->use_sg)

#define scsi_sglist(cmd) ((struct scatterlist *)(cmd)->request_buffer)

#define scsi_bufflen(cmd) ((cmd)->request_bufflen)



static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)

{

	cmd->resid = resid;

}



static inline int scsi_get_resid(struct scsi_cmnd *cmd)

{

	return cmd->resid;

}



#define scsi_for_each_sg(cmd, sg, nseg, __i)			\

	for (__i = 0, sg = scsi_sglist(cmd); __i < (nseg); __i++, (sg)++)



#endif /* _SCSI_SCSI_CMND_H */