On 09/22/2010 08:08 AM, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch updates the TCM/pSCSI plugin to support BIDI-COMMAND passthrough to the
> Linux/SCSI MidLayer using struct se_task->task_sg_bidi[] from commit 2f2e67d85860,
> and the setup of the extra struct request for the BIDI SCSI READ payload.
>
> This patchturns the original pscsi_map_task_SG() into a wrapper call for the
> new __pscsi_map_task_SG() which now accepts struct scatterlist *task_sg and u32 task_sg_num
> for struct se_task -> struct bio allocation, map and blk_make_request() calls.
>
> It also updates pscsi_blk_init_request() which now gets called twice for BIDI-COMMAND
> case. This includes the pscsi_blk_init_request() change to perform the assignment of
> 'req->cmd = &pt->pscsi_cdb[0]' and drop the original CDB memcpy() of pt->pscsi_cdb[]
> into struct request->cmd[] -> struct request->__cmd[MAX_BLK_CDB].
>
> Tested with scsi_debug w/ XDWRITE_READ32 and TCM_Loop w/ TCM/pSCSI backstores
> using 'sgv4_xdwriteread -e'.
>
> Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_pscsi.c | 111 +++++++++++++++++++++++++++--------
> drivers/target/target_core_pscsi.h | 1 +
> 2 files changed, 86 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
> index beca807..60f825d 100644
> --- a/drivers/target/target_core_pscsi.c
> +++ b/drivers/target/target_core_pscsi.c
> @@ -727,29 +727,37 @@ static void *pscsi_allocate_request(
>
> static inline void pscsi_blk_init_request(
> struct se_task *task,
> - struct pscsi_plugin_task *pt)
> + struct pscsi_plugin_task *pt,
> + struct request *req,
> + int bidi_read)
> {
> /*
> * Defined as "scsi command" in include/linux/blkdev.h.
> */
> - pt->pscsi_req->cmd_type = REQ_TYPE_BLOCK_PC;
> + req->cmd_type = REQ_TYPE_BLOCK_PC;
> + /*
> + * For the extra BIDI-COMMAND READ struct request we do not
> + * need to setup the remaining structure members
> + */
> + if (bidi_read)
> + return;
I think that if you embed this pscsi_blk_init_request() inside it's
caller it would be more clear.
But if the caller becomes too big, and this is a logical separation
then do the bidi_req->cmd_type = REQ_TYPE_BLOCK_PC in the caller
and call this one only for the main request, as before.
(BTW: Bidi does not even need cmd_type = REQ_TYPE_BLOCK_PC but
just to make sure it's safer to do it.)
> /*
> * Setup the done function pointer for struct request,
> * also set the end_io_data pointer.to struct se_task.
> */
> - pt->pscsi_req->end_io = pscsi_req_done;
> - pt->pscsi_req->end_io_data = (void *)task;
> + req->end_io = pscsi_req_done;
> + req->end_io_data = (void *)task;
> /*
> * Load the referenced struct se_task's SCSI CDB into
> * include/linux/blkdev.h:struct request->cmd
> */
> - pt->pscsi_req->cmd_len = scsi_command_size(pt->pscsi_cdb);
> - memcpy(pt->pscsi_req->cmd, pt->pscsi_cdb, pt->pscsi_req->cmd_len);
> + req->cmd_len = scsi_command_size(pt->pscsi_cdb);
> + req->cmd = &pt->pscsi_cdb[0];
> /*
> * Setup pointer for outgoing sense data.
> */
> - pt->pscsi_req->sense = (void *)&pt->pscsi_sense[0];
> - pt->pscsi_req->sense_len = 0;
> + req->sense = (void *)&pt->pscsi_sense[0];
> + req->sense_len = 0;
> }
>
> /*
> @@ -771,7 +779,7 @@ static int pscsi_blk_get_request(struct se_task *task)
> * Setup the newly allocated struct request for REQ_TYPE_BLOCK_PC,
> * and setup rq callback, CDB and sense.
> */
> - pscsi_blk_init_request(task, pt);
> + pscsi_blk_init_request(task, pt, pt->pscsi_req, 0);
> return 0;
> }
>
> @@ -1051,11 +1059,11 @@ static inline struct bio *pscsi_get_bio(struct pscsi_dev_virt *pdv, int sg_num)
> #define DEBUG_PSCSI(x...)
> #endif
>
> -/* pscsi_map_task_SG():
> - *
> - *
> - */
> -static int pscsi_map_task_SG(struct se_task *task)
> +static int __pscsi_map_task_SG(
> + struct se_task *task,
> + struct scatterlist *task_sg,
> + u32 task_sg_num,
> + int bidi_read)
> {
> struct pscsi_plugin_task *pt = (struct pscsi_plugin_task *) task->transport_req;
> struct pscsi_dev_virt *pdv = (struct pscsi_dev_virt *) task->se_dev->dev_ptr;
> @@ -1063,7 +1071,7 @@ static int pscsi_map_task_SG(struct se_task *task)
> struct page *page;
> struct scatterlist *sg;
> u32 data_len = task->task_size, i, len, bytes, off;
> - int nr_pages = (task->task_size + task->task_sg[0].offset +
> + int nr_pages = (task->task_size + task_sg[0].offset +
> PAGE_SIZE - 1) >> PAGE_SHIFT;
OK, I'm begining to suspect task->task_size is the size of what?
See below (below)
> int nr_vecs = 0, ret = 0;
> int rw = (TASK_CMD(task)->data_direction == DMA_TO_DEVICE);
> @@ -1083,7 +1091,7 @@ static int pscsi_map_task_SG(struct se_task *task)
> */
> DEBUG_PSCSI("PSCSI: nr_pages: %d\n", nr_pages);
>
> - for_each_sg(task->task_sg, sg, task->task_sg_num, i) {
> + for_each_sg(task_sg, sg, task_sg_num, i) {
> page = sg_page(sg);
> off = sg->offset;
> len = sg->length;
OK this code goes off and I don't see the rest of it. But from below with the
local use of hbio I'm assuming you are building the hbio here right?
So I had a wild thought! instead of having a page_list ==> sg_list ==> bio
could you keep bios at the task level? that is instead of sg_list.
So you do page_list ==> bio directly. Then in some places where you later
need an actual sg_list for DMA. The block layer supplies an easy bio ==> sg_list
conversion.
(Just a wild idea)
> @@ -1155,20 +1163,44 @@ static int pscsi_map_task_SG(struct se_task *task)
> }
> }
> /*
> - * Starting with v2.6.31, call blk_make_request() passing in *hbio to
> - * allocate the pSCSI task a struct request.
> + * Setup the primary pt->pscsi_req used for non BIDI and BIDI-COMMAND
> + * primary SCSI WRITE poayload mapped for struct se_task->task_sg[]
> */
> - pt->pscsi_req = blk_make_request(pdv->pdv_sd->request_queue,
> - hbio, GFP_KERNEL);
> - if (!(pt->pscsi_req)) {
> - printk(KERN_ERR "pSCSI: blk_make_request() failed\n");
> - goto fail;
> + if (!(bidi_read)) {
> + /*
> + * Starting with v2.6.31, call blk_make_request() passing in *hbio to
> + * allocate the pSCSI task a struct request.
> + */
> + pt->pscsi_req = blk_make_request(pdv->pdv_sd->request_queue,
> + hbio, GFP_KERNEL);
> + if (!(pt->pscsi_req)) {
> + printk(KERN_ERR "pSCSI: blk_make_request() failed\n");
> + goto fail;
> + }
> + /*
> + * Setup the newly allocated struct request for REQ_TYPE_BLOCK_PC,
> + * and setup rq callback, CDB and sense.
> + */
> + pscsi_blk_init_request(task, pt, pt->pscsi_req, 0);
> +
> + return task->task_sg_num;
> }
> /*
> - * Setup the newly allocated struct request for REQ_TYPE_BLOCK_PC,
> - * and setup rq callback, CDB and sense.
> + * Setup the secondary pt->pscsi_req_bidi used for the extra BIDI-COMMAND
> + * SCSI READ paylaod mapped for struct se_task->task_sg_bidi[]
> */
> - pscsi_blk_init_request(task, pt);
> + pt->pscsi_req_bidi = blk_make_request(pdv->pdv_sd->request_queue,
> + hbio, GFP_KERNEL);
> + if (!(pt->pscsi_req_bidi)) {
> + printk(KERN_ERR "pSCSI: blk_make_request() failed for BIDI\n");
> + goto fail;
> + }
> + pscsi_blk_init_request(task, pt, pt->pscsi_req_bidi, 1);
> + /*
> + * Setup the magic BIDI-COMMAND ->next_req pointer to the original
> + * pt->pscsi_req.
> + */
> + pt->pscsi_req->next_rq = pt->pscsi_req_bidi;
>
> return task->task_sg_num;
OK Now I'm sure!
You have completely missed the fact that bidi entails two sg_list(s)
two sg_num(s) and two io_byte_count(s).
The use of sg_table will clear that confusion a bit, though I wanted it
to carry an io_byte_count as well, but never came to do that.
> fail:
> @@ -1181,6 +1213,27 @@ fail:
> return ret;
> }
>
> +static int pscsi_map_task_SG(struct se_task *task)
> +{
> + int ret;
> + /*
> + * Setup the main struct request for the task->task_sg[] payload
> + */
> +
> + ret = __pscsi_map_task_SG(task, task->task_sg, task->task_sg_num, 0);
> + if (ret < 0)
> + return ret;
> +
> + if (!(task->task_sg_bidi))
> + return ret;
> + /*
> + * If present, set up the extra BIDI-COMMAND SCSI READ
> + * struct request and payload.
> + */
> + return __pscsi_map_task_SG(task, task->task_sg_bidi,
> + task->task_sg_num, 1);
What? the task->task_sg_bidi as the same sg_num as the above
task->task_sg. (See you should use sg_table to remove these
bugs.
(I wrote this comment before I wrote the above one ;-))
> +}
> +
> /* pscsi_map_task_non_SG():
> *
> *
> @@ -1438,6 +1491,12 @@ static void pscsi_req_done(struct request *req, int uptodate)
> pt->pscsi_resid = req->resid_len;
>
> pscsi_process_SAM_status(task, pt);
> +
> + if (req->next_rq != NULL) {
> + __blk_put_request(req->q, req->next_rq);
req->next_rq = NULL;
> + pt->pscsi_req_bidi = NULL;
> + }
> +
> __blk_put_request(req->q, req);
> pt->pscsi_req = NULL;
> }
> diff --git a/drivers/target/target_core_pscsi.h b/drivers/target/target_core_pscsi.h
> index 086e6f1..d3c8972 100644
> --- a/drivers/target/target_core_pscsi.h
> +++ b/drivers/target/target_core_pscsi.h
> @@ -34,6 +34,7 @@ struct pscsi_plugin_task {
> int pscsi_result;
> u32 pscsi_resid;
> struct request *pscsi_req;
> + struct request *pscsi_req_bidi;
You don't really need to, you know. You have it right here at
pscsi_req->next_rq. But it's your call
> } ____cacheline_aligned;
>
> #define PDF_HAS_CHANNEL_ID 0x01
Cheers (life is hard)
Boaz
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