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[SCSI] use scatter lists for all block pc requests and simplify hw handlers 

Here's the proof of concept for this one.  It converts scsi_wait_req to
do correct REQ_BLOCK_PC submission (and works nicely in my setup).

The final goal should be to eliminate struct scsi_request, but that
can't be done until the character submission paths of sg and st are also
modified.

There's some loss of functionality to this: retries are no longer
controllable (except by setting REQ_FASTFAIL) and the wait_req API needs
to be altered, but it looks very nice.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
James Bottomley 2005-06-05 02:07:14 -05:00 committed by James Bottomley
parent 31151ba2ce
commit e537a36d52
1 changed files with 59 additions and 37 deletions
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96
drivers/scsi/scsi_lib.c
View File

@ -232,23 +232,6 @@ void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
}
EXPORT_SYMBOL(scsi_do_req);
static void scsi_wait_done(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
struct request_queue *q = cmd->device->request_queue;
unsigned long flags;
req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
spin_lock_irqsave(q->queue_lock, flags);
if (blk_rq_tagged(req))
blk_queue_end_tag(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
if (req->waiting)
complete(req->waiting);
}
/* This is the end routine we get to if a command was never attached
* to the request. Simply complete the request without changing
* rq_status; this will cause a DRIVER_ERROR. */
@ -263,19 +246,36 @@ void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
unsigned bufflen, int timeout, int retries)
{
DECLARE_COMPLETION(wait);
sreq->sr_request->waiting = &wait;
sreq->sr_request->rq_status = RQ_SCSI_BUSY;
sreq->sr_request->end_io = scsi_wait_req_end_io;
scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
timeout, retries);
struct request *req;
if (bufflen)
req = blk_rq_map_kern(sreq->sr_device->request_queue,
sreq->sr_data_direction == DMA_TO_DEVICE,
buffer, bufflen, __GFP_WAIT);
else
req = blk_get_request(sreq->sr_device->request_queue, READ,
__GFP_WAIT);
req->flags |= REQ_NOMERGE;
req->waiting = &wait;
req->end_io = scsi_wait_req_end_io;
req->cmd_len = COMMAND_SIZE(((u8 *)cmnd)[0]);
req->sense = sreq->sr_sense_buffer;
req->sense_len = 0;
memcpy(req->cmd, cmnd, req->cmd_len);
req->timeout = timeout;
req->flags |= REQ_BLOCK_PC;
req->rq_disk = NULL;
blk_insert_request(sreq->sr_device->request_queue, req,
sreq->sr_data_direction == DMA_TO_DEVICE, NULL);
wait_for_completion(&wait);
sreq->sr_request->waiting = NULL;
if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
sreq->sr_result = req->errors;
if (req->errors)
sreq->sr_result |= (DRIVER_ERROR << 24);
__scsi_release_request(sreq);
blk_put_request(req);
}
EXPORT_SYMBOL(scsi_wait_req);
/*
@ -878,11 +878,12 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
return;
}
if (result) {
printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
"= 0x%x\n", cmd->device->host->host_no,
cmd->device->channel,
cmd->device->id,
cmd->device->lun, result);
if (!(req->flags & REQ_SPECIAL))
printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
"= 0x%x\n", cmd->device->host->host_no,
cmd->device->channel,
cmd->device->id,
cmd->device->lun, result);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
@ -1020,6 +1021,12 @@ static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
return -EOPNOTSUPP;
}
static void scsi_generic_done(struct scsi_cmnd *cmd)
{
BUG_ON(!blk_pc_request(cmd->request));
scsi_io_completion(cmd, cmd->result == 0 ? cmd->bufflen : 0, 0);
}
static int scsi_prep_fn(struct request_queue *q, struct request *req)
{
struct scsi_device *sdev = q->queuedata;
@ -1061,7 +1068,7 @@ static int scsi_prep_fn(struct request_queue *q, struct request *req)
* these two cases differently. We differentiate by looking
* at request->cmd, as this tells us the real story.
*/
if (req->flags & REQ_SPECIAL) {
if (req->flags & REQ_SPECIAL && req->special) {
struct scsi_request *sreq = req->special;
if (sreq->sr_magic == SCSI_REQ_MAGIC) {
@ -1073,7 +1080,7 @@ static int scsi_prep_fn(struct request_queue *q, struct request *req)
cmd = req->special;
} else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
if(unlikely(specials_only)) {
if(unlikely(specials_only) && !(req->flags & REQ_SPECIAL)) {
if(specials_only == SDEV_QUIESCE ||
specials_only == SDEV_BLOCK)
return BLKPREP_DEFER;
@ -1142,11 +1149,26 @@ static int scsi_prep_fn(struct request_queue *q, struct request *req)
/*
* Initialize the actual SCSI command for this request.
*/
drv = *(struct scsi_driver **)req->rq_disk->private_data;
if (unlikely(!drv->init_command(cmd))) {
scsi_release_buffers(cmd);
scsi_put_command(cmd);
return BLKPREP_KILL;
if (req->rq_disk) {
drv = *(struct scsi_driver **)req->rq_disk->private_data;
if (unlikely(!drv->init_command(cmd))) {
scsi_release_buffers(cmd);
scsi_put_command(cmd);
return BLKPREP_KILL;
}
} else {
memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
if (rq_data_dir(req) == WRITE)
cmd->sc_data_direction = DMA_TO_DEVICE;
else if (req->data_len)
cmd->sc_data_direction = DMA_FROM_DEVICE;
else
cmd->sc_data_direction = DMA_NONE;
cmd->transfersize = req->data_len;
cmd->allowed = 3;
cmd->timeout_per_command = req->timeout;
cmd->done = scsi_generic_done;
}
}