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authorBoaz Harrosh <bharrosh@panasas.com>2007-12-13 14:50:53 +0300
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-01-30 22:03:41 +0300
commit6f9a35e2dafa0f855ab051c11bdbf739745ff6f5 (patch)
tree5ca273c98b61a4d329653ef30faa2c0414eccd2b /include/scsi/scsi_cmnd.h
parent30b0c37b27485a9cb897bfe3824f6f517b8c80d6 (diff)
downloadlinux-6f9a35e2dafa0f855ab051c11bdbf739745ff6f5.tar.xz
[SCSI] bidirectional command support
At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'include/scsi/scsi_cmnd.h')
-rw-r--r--include/scsi/scsi_cmnd.h19
1 files changed, 18 insertions, 1 deletions
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index c6478bb6f963..de28aab820b0 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -2,12 +2,12 @@
#define _SCSI_SCSI_CMND_H
#include <linux/dma-mapping.h>
+#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/scatterlist.h>
-struct request;
struct Scsi_Host;
struct scsi_device;
@@ -158,4 +158,21 @@ static inline int scsi_get_resid(struct scsi_cmnd *cmd)
#define scsi_for_each_sg(cmd, sg, nseg, __i) \
for_each_sg(scsi_sglist(cmd), sg, nseg, __i)
+static inline int scsi_bidi_cmnd(struct scsi_cmnd *cmd)
+{
+ return blk_bidi_rq(cmd->request) &&
+ (cmd->request->next_rq->special != NULL);
+}
+
+static inline struct scsi_data_buffer *scsi_in(struct scsi_cmnd *cmd)
+{
+ return scsi_bidi_cmnd(cmd) ?
+ cmd->request->next_rq->special : &cmd->sdb;
+}
+
+static inline struct scsi_data_buffer *scsi_out(struct scsi_cmnd *cmd)
+{
+ return &cmd->sdb;
+}
+
#endif /* _SCSI_SCSI_CMND_H */