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SubjectChanges to Linux/SCSI target mode infrastructure for v2.6.28
From
Date
Greetings Tomo-san and Co,

With the ongoing work in Linux/SCSI for v2.6.28 to map target mode
struct scatterlist memory directly down to struct scsi_cmnd without the
need for a intermediate struct bio as with the existing
scsi_execute_async(), I have started the porting process for the
Linux/SCSI subsystem plugin in generic target core v3.0
(lio-core-2.6.git) on v2.6.28-rc6.

So far, using struct request for ICF_SCSI_CONTROL_NONSG_IO_CDB is up
using blk_rq_map_kern(), as well as ICF_SCSI_NON_DATA_CDB ops using
struct request. In order to get the first READ_10s of type
ICF_SCSI_DATA_SG_IO_CDB to work, I had to add a temporary
EXPORT_SYMBOL_GPL() for drivers/scsi/scsi_lib.c:scsi_req_map_sg() in
lio-core-2.6.git for v2.6.28-rc6 in order to get TYPE_DISK up using an
software emulated MPT-Fusion HBA driver with struct request. I have
been looking at drivers/scsi/scsi_tgt_lib.c() (which currently uses
struct request), and I figure we need something similar for the generic
target infrastructure, although __scsi_get_command() and
__scsi_put_command() are currently used in that code.

Below is what my patch looks like so far, I will probably just end up
commiting an temporary ifdef to keep scsi_execute_async() until the
proper pieces are in place and the other issues are resolved below.
>From there I will be able to drop in the proper upstream mapping bits
for struct scatterlist in
drivers/lio-core/target_core_pscsi.c:pscsi_map_task_SG() get rid of
scsi_req_map_sg() usage all together.

So far during my initial testing, I am running into a two different
exceptions. One NULL pointer deference OOPS after half dozen Open/iSCSI
login/logouts in block/elevator.c:elv_dequeue_request(). Here is the
trace from SCSI softirq context:

http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-0.png
http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-1.png

The other one is a BUG_ON in blk/blk-timeout.c:177 in blk_add_timeout()
that happens after a few hundred MB of READ_10 traffic, which also
appears to pass through elv_dequeue_request() at some point:

http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-2.png
http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-4.png

Tomo, Boaz, Jens, any comments..?

--nab

diff --git a/drivers/lio-core/target_core_pscsi.c b/drivers/lio-core/target_core_pscsi.c
index ed9f588..5161483 100644
--- a/drivers/lio-core/target_core_pscsi.c
+++ b/drivers/lio-core/target_core_pscsi.c
@@ -37,6 +37,7 @@
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/genhd.h>
+#include <linux/cdrom.h>
#include <linux/file.h>

#include <scsi/scsi.h>
@@ -44,6 +45,7 @@
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <sd.h>
+#include <sr.h>

#include <iscsi_linux_os.h>
#include <iscsi_linux_defs.h>
@@ -763,11 +765,11 @@ extern void *pscsi_allocate_request (
se_device_t *dev)
{
pscsi_plugin_task_t *pt;
- if (!(pt = kmalloc(sizeof(pscsi_plugin_task_t), GFP_KERNEL))) {
- TRACE_ERROR("Unable to allocate pscsi_plugin_task_t\n");
+
+ if (!(pt = kzalloc(sizeof(pscsi_plugin_task_t), GFP_KERNEL))) {
+ printk(KERN_ERR "Unable to allocate pscsi_plugin_task_t\n");
return(NULL);
}
- memset(pt, 0, sizeof(pscsi_plugin_task_t));

return(pt);
}
@@ -788,7 +790,44 @@ extern void pscsi_get_evpd_sn (unsigned char *buf, u32 size, se_device_t *dev)
return;
}

-/* pscsi_do_task(): (Part of se_subsystem_api_t template)
+static int pscsi_blk_get_request (se_task_t *task)
+{
+ pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
+ pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->iscsi_dev->dev_ptr;
+
+ pt->pscsi_req = blk_get_request(pdv->pdv_sd->request_queue,
+ (pt->pscsi_direction == DMA_TO_DEVICE), GFP_KERNEL);
+ if (!(pt->pscsi_req) || IS_ERR(pt->pscsi_req)) {
+ printk(KERN_ERR "PSCSI: blk_get_request() failed: %ld\n",
+ IS_ERR(pt->pscsi_req));
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+ }
+ /*
+ * Defined as "scsi command" in include/linux/blkdev.h.
+ */
+ pt->pscsi_req->cmd_type = REQ_TYPE_BLOCK_PC;
+ /*
+ * Setup the done function pointer for struct request,
+ * also set the end_io_data pointer.to se_task_t.
+ */
+ pt->pscsi_req->end_io = pscsi_req_done;
+ pt->pscsi_req->end_io_data = (void *)task;
+ /*
+ * Load the referenced se_task_t's SCSI CDB into
+ * include/linux/blkdev.h:struct request->cmd
+ */
+ pt->pscsi_req->cmd_len = COMMAND_SIZE(pt->pscsi_cdb[0]);
+ memcpy(pt->pscsi_req->cmd, pt->pscsi_cdb, pt->pscsi_req->cmd_len);
+ /*
+ * Setup pointer for outgoing sense data.
+ */
+ pt->pscsi_req->sense = (void *)&pt->pscsi_sense[0];
+ pt->pscsi_req->sense_len = 0;
+
+ return(0);
+}
+
+/* pscsi_do_task(): (Part of se_subsystem_api_t template)
*
*
*/
@@ -796,17 +835,32 @@ extern int pscsi_do_task (se_task_t *task)
{
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->iscsi_dev->dev_ptr;
- int ret;
-
- if ((ret = scsi_execute_async((struct scsi_device *)pdv->pdv_sd,
- pt->pscsi_cdb, COMMAND_SIZE(pt->pscsi_cdb[0]), pt->pscsi_direction,
- pt->pscsi_buf, task->task_size, task->task_sg_num,
- (task->se_obj_api->get_device_type(task->se_obj_ptr) == 0) ?
- PS_TIMEOUT_DISK : PS_TIMEOUT_OTHER, PS_RETRY,
- (void *)task, pscsi_req_done, GFP_KERNEL)) != 0) {
- TRACE_ERROR("PSCSI Execute(): returned: %d\n", ret);
- return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
- }
+ struct gendisk *gd = NULL;
+ /*
+ * Grab pointer to struct gendisk for TYPE_DISK and TYPE_ROM
+ * cases (eg: cases where struct scsi_device has a backing
+ * struct block_device. Also set the struct request->timeout
+ * value based on peripheral device type (from SCSI).
+ */
+ if (pdv->pdv_sd->type == TYPE_DISK) {
+ struct scsi_disk *sdisk = dev_get_drvdata(
+ &pdv->pdv_sd->sdev_gendev);
+ gd = sdisk->disk;
+ pt->pscsi_req->timeout = PS_TIMEOUT_DISK;
+ } else if (pdv->pdv_sd->type == TYPE_ROM) {
+ struct scsi_cd *scd = dev_get_drvdata(
+ &pdv->pdv_sd->sdev_gendev);
+ gd = scd->disk;
+ pt->pscsi_req->timeout = PS_TIMEOUT_OTHER;
+ } else
+ pt->pscsi_req->timeout = PS_TIMEOUT_OTHER;
+
+ pt->pscsi_req->retries = PS_RETRY;
+ /*
+ * Queue the struct request into the struct scsi_device->request_queue.
+ */
+ blk_execute_rq_nowait(pdv->pdv_sd->request_queue, gd,
+ pt->pscsi_req, 1, pscsi_req_done);

return(PYX_TRANSPORT_SENT_TO_TRANSPORT);
}
@@ -817,7 +871,14 @@ extern int pscsi_do_task (se_task_t *task)
*/
extern void pscsi_free_task (se_task_t *task)
{
- kfree(task->transport_req);
+ pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
+
+ if (pt->pscsi_req) {
+ blk_put_request(pt->pscsi_req);
+ pt->pscsi_req = NULL;
+ }
+
+ kfree(pt);
return;
}

@@ -1099,31 +1160,65 @@ extern void __pscsi_get_dev_info (pscsi_dev_virt_t *pdv, char *b, int *bl)
return;
}

-/* pscsi_map_task_SG():
+extern int scsi_req_map_sg(struct request *, struct scatterlist *, int, unsigned , gfp_t );
+
+/* pscsi_map_task_SG():
*
*
*/
-extern void pscsi_map_task_SG (se_task_t *task)
+extern int pscsi_map_task_SG (se_task_t *task)
{
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
+ int ret = 0;
+
pt->pscsi_buf = (void *)task->task_buf;

- return;
+ if (!task->task_size)
+ return(0);
+#if 0
+ if ((ret = blk_rq_map_sg(pdv->pdv_sd->request_queue,
+ pt->pscsi_req,
+ (struct scatterlist *)pt->pscsi_buf)) < 0) {
+ printk(KERN_ERR "PSCSI: blk_rq_map_sg() returned %d\n", ret);
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+ }
+#else
+ if ((ret = scsi_req_map_sg(pt->pscsi_req,
+ (struct scatterlist *)pt->pscsi_buf,
+ task->task_sg_num, task->task_size,
+ GFP_KERNEL)) < 0) {
+ printk(KERN_ERR "PSCSI: scsi_req_map_sg() failed: %d\n", ret);
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+ }
+#endif
+ return(0);
}

/* pscsi_map_task_non_SG():
*
*
*/
-extern void pscsi_map_task_non_SG (se_task_t *task)
+extern int pscsi_map_task_non_SG (se_task_t *task)
{
iscsi_cmd_t *cmd = task->iscsi_cmd;
+ pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
+ pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->iscsi_dev->dev_ptr;
unsigned char *buf = (unsigned char *) T_TASK(cmd)->t_task_buf;
+ int ret = 0;

- pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
pt->pscsi_buf = (void *)buf;

- return;
+ if (!task->task_size)
+ return(0);
+
+ if ((ret = blk_rq_map_kern(pdv->pdv_sd->request_queue,
+ pt->pscsi_req, pt->pscsi_buf,
+ task->task_size, GFP_KERNEL)) < 0) {
+ printk(KERN_ERR "PSCSI: blk_rq_map_kern() failed: %d\n", ret);
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+ }
+
+ return(0);
}

/* pscsi_CDB_inquiry():
@@ -1135,9 +1230,11 @@ extern int pscsi_CDB_inquiry (se_task_t *task, u32 size)
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;

pt->pscsi_direction = DMA_FROM_DEVICE;
- pscsi_map_task_non_SG(task);
+
+ if (pscsi_blk_get_request(task) < 0)
+ return(-1);

- return(0);
+ return(pscsi_map_task_non_SG(task));
}

extern int pscsi_CDB_none (se_task_t *task, u32 size)
@@ -1146,7 +1243,7 @@ extern int pscsi_CDB_none (se_task_t *task, u32 size)

pt->pscsi_direction = DMA_NONE;

- return(0);
+ return(pscsi_blk_get_request(task));
}

/* pscsi_CDB_read_non_SG():
@@ -1158,9 +1255,11 @@ extern int pscsi_CDB_read_non_SG (se_task_t *task, u32 size)
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;

pt->pscsi_direction = DMA_FROM_DEVICE;
- pscsi_map_task_non_SG(task);

- return(0);
+ if (pscsi_blk_get_request(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+
+ return(pscsi_map_task_non_SG(task));
}

/* pscsi_CDB_read_SG():
@@ -1172,7 +1271,12 @@ extern int pscsi_CDB_read_SG (se_task_t *task, u32 size)
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;

pt->pscsi_direction = DMA_FROM_DEVICE;
- pscsi_map_task_SG(task);
+
+ if (pscsi_blk_get_request(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+
+ if (pscsi_map_task_SG(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);

return(task->task_sg_num);
}
@@ -1186,9 +1290,11 @@ extern int pscsi_CDB_write_non_SG (se_task_t *task, u32 size)
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;

pt->pscsi_direction = DMA_TO_DEVICE;
- pscsi_map_task_non_SG(task);

- return(0);
+ if (pscsi_blk_get_request(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+
+ return(pscsi_map_task_non_SG(task));
}

/* pscsi_CDB_write_SG():
@@ -1200,7 +1306,12 @@ extern int pscsi_CDB_write_SG (se_task_t *task, u32 size)
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;

pt->pscsi_direction = DMA_TO_DEVICE;
- pscsi_map_task_SG(task);
+
+ if (pscsi_blk_get_request(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+
+ if (pscsi_map_task_SG(task) < 0)
+ return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);

return(task->task_sg_num);
}
@@ -1386,22 +1497,25 @@ extern void pscsi_shutdown_hba (se_hba_t *hba)
*
*
*/
-//#warning FIXME: We can do some custom handling of HBA fuckups here.
-extern inline void pscsi_process_SAM_status (se_task_t *task, unsigned char *cdb, int result)
+static inline void pscsi_process_SAM_status (
+ se_task_t *task,
+ pscsi_plugin_task_t *pt)
{
- if ((task->task_scsi_status = status_byte(result))) {
+ if ((task->task_scsi_status = status_byte(pt->pscsi_result))) {
task->task_scsi_status <<= 1;
- PYXPRINT("Parallel SCSI Status Byte exception - ITT: 0x%08x Task: %p CDB: 0x%02x"
- " Result: 0x%08x\n", task->iscsi_cmd->init_task_tag, task, cdb[0], result);
+ PYXPRINT("PSCSI Status Byte exception at task: %p CDB: 0x%02x"
+ " Result: 0x%08x\n", task, pt->pscsi_cdb[0],
+ pt->pscsi_result);
}

- switch (host_byte(result)) {
+ switch (host_byte(pt->pscsi_result)) {
case DID_OK:
transport_complete_task(task, (!task->task_scsi_status));
break;
default:
- PYXPRINT("Parallel SCSI Host Byte exception - ITT: 0x%08x Task: %p CDB: 0x%02x"
- " Result: 0x%08x\n", task->iscsi_cmd->init_task_tag, task, cdb[0], result);
+ PYXPRINT("PSCSI Host Byte exception at task: %p CDB: 0x%02x"
+ " Result: 0x%08x\n", task, pt->pscsi_cdb[0],
+ pt->pscsi_result);
task->task_scsi_status = SAM_STAT_CHECK_CONDITION;
task->task_error_status = PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
task->iscsi_cmd->transport_error_status = PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
@@ -1412,21 +1526,17 @@ extern inline void pscsi_process_SAM_status (se_task_t *task, unsigned char *cdb
return;
}

-extern void pscsi_req_done (void *data, char *sense, int result, int data_len)
+extern void pscsi_req_done (struct request *req, int uptodate)
{
- se_task_t *task = (se_task_t *)data;
+ se_task_t *task = (se_task_t *)req->end_io_data;
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *)task->transport_req;
-#if 0
- printk("pscsi_req_done(): result: %08x, sense: %p data_len: %d\n",
- result, sense, data_len);
-#endif
- pt->pscsi_result = result;
- pt->pscsi_data_len = data_len;
-
- if (result != 0)
- memcpy(pt->pscsi_sense, sense, SCSI_SENSE_BUFFERSIZE);
+
+ pt->pscsi_result = req->errors;
+ pt->pscsi_resid = req->data_len;

- pscsi_process_SAM_status(task, &pt->pscsi_cdb[0], result);
+ pscsi_process_SAM_status(task, pt);
+
+ __blk_put_request(req->q, req);
+
return;
}
-
diff --git a/drivers/lio-core/target_core_pscsi.h b/drivers/lio-core/target_core_pscsi.h
index 980587d..090f0d2 100644
--- a/drivers/lio-core/target_core_pscsi.h
+++ b/drivers/lio-core/target_core_pscsi.h
@@ -90,7 +90,7 @@ extern struct scatterlist *pscsi_get_SG (se_task_t *);
extern u32 pscsi_get_SG_count (se_task_t *);
extern int pscsi_set_non_SG_buf (unsigned char *, se_task_t *);
extern void pscsi_shutdown_hba (struct se_hba_s *);
-extern void pscsi_req_done (void *, char *, int, int);
+extern void pscsi_req_done (struct request *, int);
#endif

#include <linux/device.h>
@@ -104,8 +104,9 @@ typedef struct pscsi_plugin_task_s {
unsigned char pscsi_sense[SCSI_SENSE_BUFFERSIZE];
int pscsi_direction;
int pscsi_result;
- u32 pscsi_data_len;
+ u32 pscsi_resid;
void *pscsi_buf;
+ struct request *pscsi_req;
} pscsi_plugin_task_t;

#define PDF_HAS_CHANNEL_ID 0x01
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f5d3b96..9e03a02 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -303,8 +303,8 @@ static void scsi_bi_endio(struct bio *bio, int error)
* request can be sent to the block layer. We do not trust the scatterlist
* sent to use, as some ULDs use that struct to only organize the pages.
*/
-static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
- int nsegs, unsigned bufflen, gfp_t gfp)
+int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
+ int nsegs, unsigned bufflen, gfp_t gfp)
{
struct request_queue *q = rq->q;
int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -379,6 +379,8 @@ free_bios:
return err;
}

+EXPORT_SYMBOL_GPL(scsi_req_map_sg);
+
/**
* scsi_execute_async - insert request
* @sdev: scsi device



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