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 --- drivers/scsi/scsi_error.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/scsi/scsi_error.c') diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 4f4edc388c0..045a0868fc7 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -618,9 +618,11 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses, memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd)); ses->data_direction = scmd->sc_data_direction; ses->sdb = scmd->sdb; + ses->next_rq = scmd->request->next_rq; ses->result = scmd->result; memset(&scmd->sdb, 0, sizeof(scmd->sdb)); + scmd->request->next_rq = NULL; if (sense_bytes) { scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE, @@ -673,6 +675,7 @@ void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses) memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd)); scmd->sc_data_direction = ses->data_direction; scmd->sdb = ses->sdb; + scmd->request->next_rq = ses->next_rq; scmd->result = ses->result; } EXPORT_SYMBOL(scsi_eh_restore_cmnd); -- cgit v1.2.3-18-g5258