From 6f9a35e2dafa0f855ab051c11bdbf739745ff6f5 Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Thu, 13 Dec 2007 13:50:53 +0200 Subject: [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 Signed-off-by: James Bottomley --- include/scsi/scsi_cmnd.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'include/scsi/scsi_cmnd.h') 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 +#include #include #include #include #include -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 */ -- cgit v1.2.3-59-g8ed1b