[dm-devel] [PATCH 2/4] scsi_dh: rdac handler: Make rdac hardware handler async
Chandra Seetharaman
sekharan at us.ibm.com
Wed Sep 30 02:08:23 UTC 2009
Batch up MODE_SELECT in rdac device handler.
LSI RDAC storage has the capability of handling mode selects for
multiple luns in a same command. Make use of that ability to send
as few MODE SELECTs as possible to the storage controller as possible.
This patch creates a work queue and queues up activate requests
when a MODE SELECT is sent down the wire. When that MODE SELECT
completes, it compiles queued up activate requests for multiple
luns into a single MODE SELECT.
This reduces the time to do failover/failback of large number of LUNS.
Signed-off-by: Babu Moger <babu.moger at lsi.com>
Signed-off-by: Chandra Seetharaman <sekharan at us.ibm.com>
---
drivers/scsi/device_handler/scsi_dh_rdac.c | 117 ++++++++++++++++++++++++++---
1 file changed, 104 insertions(+), 13 deletions(-)
Index: linux-2.6.31/drivers/scsi/device_handler/scsi_dh_rdac.c
===================================================================
--- linux-2.6.31.orig/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ linux-2.6.31/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -22,6 +22,7 @@
#include <scsi/scsi.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>
+#include <linux/workqueue.h>
#define RDAC_NAME "rdac"
#define RDAC_RETRY_COUNT 5
@@ -135,6 +136,11 @@ struct rdac_controller {
struct rdac_pg_legacy legacy;
struct rdac_pg_expanded expanded;
} mode_select;
+ spinlock_t ms_lock;
+ int ms_queued;
+ struct work_struct ms_work;
+ struct scsi_device *ms_sdev;
+ struct list_head ms_head;
};
struct c8_inquiry {
u8 peripheral_info;
@@ -195,8 +201,17 @@ static const char *lun_state[] =
"owned (AVT mode)",
};
+struct rdac_queue_data {
+ struct list_head entry;
+ struct rdac_dh_data *h;
+ activate_complete callback_fn;
+ void *callback_data;
+};
+
static LIST_HEAD(ctlr_list);
static DEFINE_SPINLOCK(list_lock);
+static struct workqueue_struct *kmpath_rdacd;
+static void send_mode_select(struct work_struct *work);
static inline struct rdac_dh_data *get_rdac_data(struct scsi_device *sdev)
{
@@ -253,7 +268,6 @@ static struct request *rdac_failover_get
rdac_pg->subpage_code = 0x1;
rdac_pg->page_len[0] = 0x01;
rdac_pg->page_len[1] = 0x28;
- rdac_pg->lun_table[h->lun] = 0x81;
} else {
struct rdac_pg_legacy *rdac_pg;
@@ -263,7 +277,6 @@ static struct request *rdac_failover_get
common = &rdac_pg->common;
rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
rdac_pg->page_len = 0x68;
- rdac_pg->lun_table[h->lun] = 0x81;
}
common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
@@ -297,6 +310,7 @@ static void release_controller(struct kr
struct rdac_controller *ctlr;
ctlr = container_of(kref, struct rdac_controller, kref);
+ flush_workqueue(kmpath_rdacd);
spin_lock(&list_lock);
list_del(&ctlr->node);
spin_unlock(&list_lock);
@@ -326,6 +340,11 @@ static struct rdac_controller *get_contr
memcpy(ctlr->slot_id, slot_id, SLOT_ID_LEN);
kref_init(&ctlr->kref);
ctlr->use_ms10 = -1;
+ ctlr->ms_queued = 0;
+ ctlr->ms_sdev = NULL;
+ spin_lock_init(&ctlr->ms_lock);
+ INIT_WORK(&ctlr->ms_work, send_mode_select);
+ INIT_LIST_HEAD(&ctlr->ms_head);
list_add(&ctlr->node, &ctlr_list);
done:
spin_unlock(&list_lock);
@@ -445,8 +464,7 @@ static int set_mode_select(struct scsi_d
return err;
}
-static int mode_select_handle_sense(struct scsi_device *sdev,
- unsigned char *sensebuf)
+static int mode_select_handle_sense(unsigned char *sensebuf)
{
struct scsi_sense_hdr sense_hdr;
int err = SCSI_DH_IO, ret;
@@ -478,7 +496,7 @@ static int mode_select_handle_sense(stru
err = SCSI_DH_RETRY;
break;
default:
- sdev_printk(KERN_INFO, sdev,
+ printk(KERN_INFO
"MODE_SELECT failed with sense %02x/%02x/%02x.\n",
sense_hdr.sense_key, sense_hdr.asc, sense_hdr.ascq);
}
@@ -487,11 +505,29 @@ done:
return err;
}
-static int send_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
+static void send_mode_select(struct work_struct *work)
{
+ struct rdac_controller *ctlr =
+ container_of(work, struct rdac_controller, ms_work);
struct request *rq;
+ struct scsi_device *sdev = ctlr->ms_sdev;
+ struct rdac_dh_data *h = get_rdac_data(sdev);
struct request_queue *q = sdev->request_queue;
int err, retry_cnt = RDAC_RETRY_COUNT;
+ struct rdac_queue_data *tmp, *qdata;
+ LIST_HEAD(list);
+ u8 *lun_table;
+
+ spin_lock(&ctlr->ms_lock);
+ list_splice_init(&ctlr->ms_head, &list);
+ ctlr->ms_queued = 0;
+ ctlr->ms_sdev = NULL;
+ spin_unlock(&ctlr->ms_lock);
+
+ if (ctlr->use_ms10)
+ lun_table = ctlr->mode_select.expanded.lun_table;
+ else
+ lun_table = ctlr->mode_select.legacy.lun_table;
retry:
err = SCSI_DH_RES_TEMP_UNAVAIL;
@@ -499,13 +535,17 @@ retry:
if (!rq)
goto done;
- sdev_printk(KERN_INFO, sdev, "%s MODE_SELECT command.\n",
+ list_for_each_entry(qdata, &list, entry) {
+ lun_table[qdata->h->lun] = 0x81;
+ }
+
+ printk(KERN_INFO "%s MODE_SELECT command.\n",
(retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");
err = blk_execute_rq(q, NULL, rq, 1);
blk_put_request(rq);
if (err != SCSI_DH_OK) {
- err = mode_select_handle_sense(sdev, h->sense);
+ err = mode_select_handle_sense(h->sense);
if (err == SCSI_DH_RETRY && retry_cnt--)
goto retry;
}
@@ -513,10 +553,45 @@ retry:
h->state = RDAC_STATE_ACTIVE;
done:
- return err;
+ list_for_each_entry_safe(qdata, tmp, &list, entry) {
+ list_del(&qdata->entry);
+ if (err == SCSI_DH_OK)
+ qdata->h->state = RDAC_STATE_ACTIVE;
+ if (qdata->callback_fn)
+ qdata->callback_fn(qdata->callback_data, err);
+ kfree(qdata);
+ }
+ return;
}
-static int rdac_activate(struct scsi_device *sdev, activate_complete fn, void *data)
+static int queue_mode_select(struct scsi_device *sdev,
+ activate_complete fn, void *data)
+{
+ struct rdac_queue_data *qdata;
+ struct rdac_controller *ctlr;
+
+ qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
+ if (!qdata)
+ return SCSI_DH_RETRY;
+
+ qdata->h = get_rdac_data(sdev);
+ qdata->callback_fn = fn;
+ qdata->callback_data = data;
+
+ ctlr = qdata->h->ctlr;
+ spin_lock(&ctlr->ms_lock);
+ list_add_tail(&qdata->entry, &ctlr->ms_head);
+ if (!ctlr->ms_queued) {
+ ctlr->ms_queued = 1;
+ ctlr->ms_sdev = sdev;
+ queue_work(kmpath_rdacd, &ctlr->ms_work);
+ }
+ spin_unlock(&ctlr->ms_lock);
+ return SCSI_DH_OK;
+}
+
+static int rdac_activate(struct scsi_device *sdev,
+ activate_complete fn, void *data)
{
struct rdac_dh_data *h = get_rdac_data(sdev);
int err = SCSI_DH_OK;
@@ -536,8 +611,11 @@ static int rdac_activate(struct scsi_dev
if (err != SCSI_DH_OK)
goto done;
}
- if (h->lun_state == RDAC_LUN_UNOWNED)
- err = send_mode_select(sdev, h);
+ if (h->lun_state == RDAC_LUN_UNOWNED) {
+ err = queue_mode_select(sdev, fn, data);
+ if (err == SCSI_DH_OK)
+ return 0;
+ }
done:
if (fn)
fn(data, err);
@@ -726,13 +804,26 @@ static int __init rdac_init(void)
int r;
r = scsi_register_device_handler(&rdac_dh);
- if (r != 0)
+ if (r != 0) {
printk(KERN_ERR "Failed to register scsi device handler.");
+ goto done;
+ }
+
+ /*
+ * Create workqueue to handle mode selects for rdac
+ */
+ kmpath_rdacd = create_singlethread_workqueue("kmpath_rdacd");
+ if (!kmpath_rdacd) {
+ scsi_unregister_device_handler(&rdac_dh);
+ printk(KERN_ERR "kmpath_rdacd creation failed.\n");
+ }
+done:
return r;
}
static void __exit rdac_exit(void)
{
+ destroy_workqueue(kmpath_rdacd);
scsi_unregister_device_handler(&rdac_dh);
}
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