I have found the issue.
in kernel prior to RHEL 6.0 blk_pc_request(rq) is define as:
#define blk_pc_request(rq) ((rq)->flags & REQ_BLOCK_PC)
while in RHEL 6.0 it is define as:
#define blk_pc_request(rq) ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
So, the issue was adding I was REQ_NOMERGE flag in cmd_type field of the request. This was making blk_pc_request(rq) to return false and thats why IOs were not going to scsi layer.
thanks,
ajit
On Wed, Apr 20, 2011 at 6:06 PM, ajit jain <ajit4mail@xxxxxxxxx> wrote:
Hi All,
I have written a func to send a CDB on a scsi device from the kernel. For that I am getting a request and queueing for execution.
But blk_execute_rq() func is setting errors field of request to 65536 and sense length is set but all the fields in sense header is
0.
I dont know what I am missing, any suggestion would be great help.
snippet of the code
===========================
rq = blk_get_request(q, rw, __GFP_WAIT);
if(!rq){
goto out;
}
if (buflen && blk_rq_map_kern(q, rq, buf, buflen, __GFP_WAIT)){
goto out;
}
rq->cmd_len = cmdlen;
memcpy(rq->cmd, cmd, cmdlen);
memset(sense, 0, sizeof(sense));
rq->sense_len = 0;
rq->sense = sense;
rq->cmd_type |= REQ_TYPE_BLOCK_PC;
rq->cmd_type |= REQ_NOMERGE;
rq->timeout = WRITE_SCSI_TIMEOUT; //WRITE_SCSI_TIMEOUT is set to 60 sec
blk_execute_rq(q, bd_disk, rq, 0);
error = rq->errors;
if( error ){
dbg("error in blk_execute_rq error %d",error);
}
if(rq->sense_len){
process_sense_info(rq->sense);
} else {
info("no sense available");
}
==========================================
thanks,
ajit
PS:We can not use sg_ioctl interface because code expects user space application only to invoke sg_ioctl that the reason it does a copyin.
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