[PATCH] [Target_Core_Mod/PSCSI]: Remove usage of scsi_req_map_sg()for v2.6.28-FINAL

From: Nicholas A. Bellinger
Date: Sat Dec 13 2008 - 23:17:59 EST

Greetings all,

For those following along, this patch is made against lio-core-2.6.git/master
and tested on v2.6.28-rc7. The lio-core-2.6.git tree can be located at:
http://git.kernel.org/?p=linux/kernel/git/nab/lio-core-2.6.git

Subject: [PATCH] [Target_Core_Mod/PSCSI]: Remove usage of scsi_req_map_sg() for v2.6.28-FINAL

This patch removes the usage of the soon to be defunct drivers/scsi/scsi_lib.c:scsi_req_map_sg().
It adds similar logic to pscsi_map_task_SG(), which just like the scsi_req_map_sg()
still depends upon BIOs when sending struct scatterlist memory into Linux/SCSI using
struct request into struct scsi_device->request_queue using block/blk-exec.c:blk_execute_rq_nowait()

This code will be changing against during v2.6.29, at which time pscsi_map_task_SG() will
be converted to get rid of BIO and use the yet-to-be-determined Linux/SCSI passthrough that accepts
struct scatterlist, struct scatterlist->page_link, or struct page.

Also, this patch removes pscsi_plugin_task_t->pscsi_buf, which was used as void * pointer
for se_task_->task_sg (for scatterlists) or T_TASK(se_cmd_t)->t_task_buf. It also removes
the last remaining references to iSCSI.

Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/lio-core/target_core_pscsi.c | 175 ++++++++++++++++++++++++----------
drivers/lio-core/target_core_pscsi.h | 3 +-
2 files changed, 125 insertions(+), 53 deletions(-)

diff --git a/drivers/lio-core/target_core_pscsi.c b/drivers/lio-core/target_core_pscsi.c
index e8a2c95..d417b1e 100644
--- a/drivers/lio-core/target_core_pscsi.c
+++ b/drivers/lio-core/target_core_pscsi.c
@@ -1,7 +1,7 @@
/*********************************************************************************
* Filename: target_core_pscsi.c
*
- * This file contains the iSCSI <-> Parallel SCSI transport specific functions.
+ * This file contains the generic target mode <-> Linux SCSI subsystem plugin.
*
* Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
* Copyright (c) 2005, 2006, 2007 SBE, Inc.
@@ -69,9 +69,6 @@

#define ISPRINT(a) ((a >=' ')&&(a <= '~'))

-#warning FIXME: Obtain via IOCTL for Initiator Drivers
-#define INIT_CORE_NAME "SBE, Inc. iSCSI Initiator Core"
-
extern se_global_t *se_global;
extern struct block_device *linux_blockdevice_claim(int, int, void *);
extern int linux_blockdevice_release(int, int, struct block_device *);
@@ -592,7 +589,7 @@ extern void pscsi_free_device (void *p)

pdv->pdv_sd = NULL;
}
-
+
kfree(pdv);
return;
}
@@ -605,19 +602,18 @@ extern int pscsi_transport_complete (se_task_t *task)
{
pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
struct scsi_device *sd = (struct scsi_device *) pdv->pdv_sd;
- void *pscsi_buf;
int result;
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
unsigned char *cdb = &pt->pscsi_cdb[0];

result = pt->pscsi_result;
- pscsi_buf = pt->pscsi_buf;

# ifdef LINUX_EVPD_PAGE_CHECK
if ((cdb[0] == INQUIRY) && host_byte(result) == DID_OK) {
u32 len = 0;
- unsigned char *dst = (unsigned char *)pscsi_buf, *iqn = NULL;
- unsigned char buf[EVPD_BUF_LEN];
+ unsigned char *dst = (unsigned char *)
+ T_TASK(task->task_se_cmd)->t_task_buf;
+ unsigned char buf[EVPD_BUF_LEN], *iqn = NULL;
se_hba_t *hba = task->se_dev->se_hba;

/*
@@ -699,7 +695,8 @@ extern int pscsi_transport_complete (se_task_t *task)
goto after_mode_sense;

if (TASK_CMD(task)->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY) {
- unsigned char *buf = (unsigned char *)pscsi_buf;
+ unsigned char *buf = (unsigned char *)
+ T_TASK(task->task_se_cmd)->t_task_buf;

if (cdb[0] == MODE_SENSE_10) {
if (!(buf[3] & 0x80))
@@ -724,7 +721,7 @@ after_mode_sense:
if (((cdb[0] == MODE_SELECT) || (cdb[0] == MODE_SELECT_10)) &&
(status_byte(result) << 1) == SAM_STAT_GOOD) {
unsigned char *buf;
- struct scatterlist *sg = (struct scatterlist *)pscsi_buf;
+ struct scatterlist *sg = task->task_sg;
u16 bdl;
u32 blocksize;

@@ -872,6 +869,10 @@ extern int pscsi_do_task (se_task_t *task)
extern void pscsi_free_task (se_task_t *task)
{
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
+ /*
+ * We do not release the bio(s) here associated with this task, as this is
+ * handled by bio_put() and pscsi_bi_endio().
+ */
kfree(pt);
return;
}
@@ -1089,7 +1090,7 @@ extern void pscsi_get_hba_info (se_hba_t *hba, char *b, int *bl)
{
struct Scsi_Host *sh = (struct Scsi_Host *) hba->hba_ptr;

- *bl += sprintf(b+*bl, "iSCSI Host ID: %u SCSI Host ID: %u\n",
+ *bl += sprintf(b+*bl, "Core Host ID: %u SCSI Host ID: %u\n",
hba->hba_id, sh->host_no);
*bl += sprintf(b+*bl, " Parallel SCSI HBA: %s <local>\n",
(sh->hostt->name) ? (sh->hostt->name) : "Unknown");
@@ -1154,7 +1155,29 @@ extern void __pscsi_get_dev_info (pscsi_dev_virt_t *pdv, char *b, int *bl)
return;
}

-extern int scsi_req_map_sg(struct request *, struct scatterlist *, int, unsigned , gfp_t );
+static void pscsi_bi_endio (struct bio *bio, int error)
+{
+ bio_put(bio);
+}
+
+static inline struct bio *pscsi_get_bio (int sg_num)
+{
+ struct bio *bio;
+
+ if (!(bio = bio_alloc(GFP_KERNEL, sg_num))) {
+ printk(KERN_ERR "PSCSI: bio_alloc() failed\n");
+ return(NULL);
+ }
+ bio->bi_end_io = pscsi_bi_endio;
+
+ return(bio);
+}
+
+#if 1
+#define DEBUG_PSCSI(x...) printk(x)
+#else
+#define DEBUG_PSCSI(x...)
+#endif

/* pscsi_map_task_SG():
*
@@ -1163,26 +1186,98 @@ extern int scsi_req_map_sg(struct request *, struct scatterlist *, int, unsigne
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_sg;
+ struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
+ struct page *page;
+ struct request *rq = pt->pscsi_req;
+ struct scatterlist *sg;
+ u32 data_len = task->task_size, i, len, bytes, off;
+ int nr_pages = (task->task_size + task->task_sg[0].offset +
+ PAGE_SIZE - 1) >> PAGE_SHIFT;
+ int nr_vecs = 0, ret = 0;

if (!task->task_size)
return(0);
-#if 0
- if ((ret = blk_rq_map_sg(pdv->pdv_sd->request_queue,
- pt->pscsi_req, task->task_sg)) < 0) {
- printk(KERN_ERR "PSCSI: blk_rq_map_sg() returned %d\n", ret);
- return(PYX_TRANSPORT_LOGICAL_UNIT_COMMUNICATION_FAILURE);
+ /*
+ * For SCF_SCSI_DATA_SG_IO_CDB, Use fs/bio.c:bio_add_page() to setup
+ * the bio_vec maplist from LIO-SE se_mem_t -> task->task_sg ->
+ * struct scatterlist memory. The se_task_t->task_sg[] currently needs
+ * to be attached to struct bios for submission to Linux/SCSI using
+ * struct request to struct scsi_device->request_queue.
+ *
+ * Note that this will be changing post v2.6.28 as Target_Core_Mod/pSCSI
+ * is ported to upstream SCSI passthrough functionality that accepts
+ * struct scatterlist->page_link or struct page as a paraemeter.
+ */
+ DEBUG_PSCSI("PSCSI: nr_pages: %d\n", nr_pages);
+
+ for_each_sg(task->task_sg, sg, task->task_sg_num, i) {
+ page = sg_page(sg);
+ off = sg->offset;
+ len = sg->length;
+
+ DEBUG_PSCSI("PSCSI: i: %d page: %p len: %d off: %d\n", i,
+ page, len, off);
+
+ while (len > 0 && data_len > 0) {
+ bytes = min_t(unsigned int, len, PAGE_SIZE - off);
+ bytes = min(bytes, data_len);
+
+ if (!(bio)) {
+ nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
+ nr_pages -= nr_vecs;
+
+ if (!(bio = pscsi_get_bio(nr_vecs)))
+ goto fail;
+
+ DEBUG_PSCSI("PSCSI: Allocated bio: %p, nr_vecs: %d\n",
+ bio, nr_vecs);
+ tbio = tbio->bi_next = bio;
+ }
+
+ DEBUG_PSCSI("PSCSI: Calling bio_add_page() i: %d bio: %p"
+ " page: %p len: %d off: %d\n", i, bio, page,
+ len, off);
+
+ if ((ret = bio_add_page(bio, page, bytes, off)) != bytes)
+ goto fail;
+
+ DEBUG_PSCSI("PSCSI: bio->bi_vcnt: %d nr_vecs: %d\n",
+ bio->bi_vcnt, nr_vecs);
+
+ if (bio->bi_vcnt >= nr_vecs) {
+ bio->bi_flags &= ~(1 << BIO_SEG_VALID);
+ if (rq_data_dir(rq) == WRITE)
+ bio->bi_rw |= (1 << BIO_RW);
+ blk_queue_bounce(rq->q, &bio);
+
+ DEBUG_PSCSI("PSCSI: Calling blk_rq_append_bio(): i: %d"
+ " bio: %p\n", i, bio);
+ if ((ret = blk_rq_append_bio(rq->q, rq, bio)) < 0)
+ goto fail;
+
+ bio = NULL;
+ }
+
+ page++;
+ len -= bytes;
+ data_len -= bytes;
+ off = 0;
+
+ }
}
-#else
- if ((ret = scsi_req_map_sg(pt->pscsi_req, task->task_sg,
- 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);
+
+ rq->buffer = rq->data = NULL;
+ rq->data_len = task->task_size;
+
+ return(task->task_sg_num);
+fail:
+ while (hbio) {
+ bio = hbio;
+ hbio = hbio->bi_next;
+ bio->bi_next = NULL;
+ bio_endio(bio, 0);
}
-#endif
- return(0);
+ return(ret);
}

/* pscsi_map_task_non_SG():
@@ -1193,17 +1288,14 @@ extern int pscsi_map_task_non_SG (se_task_t *task)
{
se_cmd_t *cmd = TASK_CMD(task);
pscsi_plugin_task_t *pt = (pscsi_plugin_task_t *) task->transport_req;
- unsigned char *buf = (unsigned char *) T_TASK(cmd)->t_task_buf;
pscsi_dev_virt_t *pdv = (pscsi_dev_virt_t *) task->se_dev->dev_ptr;
int ret = 0;

- pt->pscsi_buf = (void *)buf;
-
if (!task->task_size)
return(0);

if ((ret = blk_rq_map_kern(pdv->pdv_sd->request_queue,
- pt->pscsi_req, pt->pscsi_buf,
+ pt->pscsi_req, T_TASK(cmd)->t_task_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);
@@ -1416,25 +1508,6 @@ extern u32 pscsi_get_queue_depth (se_device_t *dev)

extern void pscsi_shutdown_hba (se_hba_t *hba)
{
- struct Scsi_Host *sh = (struct Scsi_Host *)hba->hba_ptr;
-
- if (strcmp(sh->hostt->name, INIT_CORE_NAME)) {
- /*
- * Perhaps we could force a host-reset here if outstanding tasks
- * have not come back..
- */
- return;
- }
-#warning FIXME: iscsi_global breakage in iscsi_target_pscsi.c
-#if 0
- if (!iscsi_global->ti_forcechanoffline)
- return;
-
- /*
- * Notify the iSCSI Initiator to perform pause/forcechanoffline operations
- */
- iscsi_global->ti_forcechanoffline(hba->hba_ptr);
-#endif
return;
}

diff --git a/drivers/lio-core/target_core_pscsi.h b/drivers/lio-core/target_core_pscsi.h
index c70bb65..929fbb9 100644
--- a/drivers/lio-core/target_core_pscsi.h
+++ b/drivers/lio-core/target_core_pscsi.h
@@ -1,7 +1,7 @@
/*********************************************************************************
* Filename: target_core_pscsi.h
*
- * This file contains the iSCSI <-> Parallel SCSI transport
+ * This file contains the generic target mode <-> Linux SCSI subsystem plugin.
* specific definitions and prototypes.
*
* Copyright (c) 2003, 2004, 2005 PyX Technologies, Inc.
@@ -101,7 +101,6 @@ typedef struct pscsi_plugin_task_s {
int pscsi_direction;
int pscsi_result;
u32 pscsi_resid;
- void *pscsi_buf;
struct request *pscsi_req;
} pscsi_plugin_task_t;

--
1.5.4.1



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/