[dm-devel] RE: [PATCH 2/4] scsi_dh: Make rdac hardware handler's activate() async
Moger, Babu
Babu.Moger at lsi.com
Thu Oct 22 23:30:18 UTC 2009
I have tested this patch on LSI rdac storage. It works pretty well..
> -----Original Message-----
> From: linux-scsi-owner at vger.kernel.org [mailto:linux-scsi-
> owner at vger.kernel.org] On Behalf Of Chandra Seetharaman
> Sent: Wednesday, October 21, 2009 11:23 AM
> To: linux-scsi at vger.kernel.org
> Cc: dm-devel at redhat.com; Moger, Babu; michaelc at cs.wisc.edu;
> Benoit_Arthur at emc.com; Eddie.Williams at steeleye.com;
> berthiaume_wayne at emc.com; Chandra Seetharaman
> Subject: [PATCH 2/4] scsi_dh: Make rdac hardware handler's activate()
> async
>
> 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>
Tested-by: Babu Moger <babu.moger at lsi.com>
>
> ---
> drivers/scsi/device_handler/scsi_dh_rdac.c | 108
> +++++++++++++++++++++++++++--
> 1 file changed, 100 insertions(+), 8 deletions(-)
>
> Index: linux-2.6.32-rc5/drivers/scsi/device_handler/scsi_dh_rdac.c
> ===================================================================
> --- linux-2.6.32-rc5.orig/drivers/scsi/device_handler/scsi_dh_rdac.c
> 2009-10-20 18:26:14.000000000 -0700
> +++ linux-2.6.32-rc5/drivers/scsi/device_handler/scsi_dh_rdac.c 2009-
> 10-20 18:26:29.000000000 -0700
> @@ -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
> @@ -138,7 +139,13 @@
> } mode_select;
> u8 index;
> u8 array_name[ARRAY_LABEL_LEN];
> + 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;
> u8 page_code; /* 0xC8 */
> @@ -198,8 +205,17 @@
> "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);
>
> /*
> * module parameter to enable rdac debug logging.
> @@ -281,7 +297,6 @@
> 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;
>
> @@ -291,7 +306,6 @@
> 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;
> @@ -325,6 +339,7 @@
> 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);
> @@ -363,6 +378,11 @@
>
> 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);
> @@ -490,7 +510,7 @@
> }
>
> static int mode_select_handle_sense(struct scsi_device *sdev,
> - unsigned char *sensebuf)
> + unsigned char *sensebuf)
> {
> struct scsi_sense_hdr sense_hdr;
> int err = SCSI_DH_IO, ret;
> @@ -533,11 +553,29 @@
> 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;
> @@ -545,6 +583,10 @@
> if (!rq)
> goto done;
>
> + list_for_each_entry(qdata, &list, entry) {
> + lun_table[qdata->h->lun] = 0x81;
> + }
> +
> RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
> "%s MODE_SELECT command",
> (char *) h->ctlr->array_name, h->ctlr->index,
> @@ -565,7 +607,41 @@
> }
>
> 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 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,
> @@ -578,8 +654,11 @@
> 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);
> @@ -793,13 +872,26 @@
> 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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