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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: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
FUJITA Tomonori 2007-05-26 14:04:03 +09:00 committed by James Bottomley
parent 9ef3e4a452
commit 824d7b570b
2 changed files with 58 additions and 0 deletions
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38
drivers/scsi/scsi_lib.c
View File

@ -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);

20
include/scsi/scsi_cmnd.h
View File

@ -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 */