[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>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index a2e0c1032491..53e170586c26 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -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 */