--- /dev/null
+/*
+ * Copyright (C) 2005 Mike Christie, All rights reserved.
+ * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
+ * Authors: Mike Christie
+ * Dave Wysochanski
+ *
+ * This file is released under the GPL.
+ *
+ * This module implements the specific path activation code for
+ * HP StorageWorks and FSC FibreCat Asymmetric (Active/Passive)
+ * storage arrays.
+ * These storage arrays have controller-based failover, not
+ * LUN-based failover. However, LUN-based failover is the design
+ * of dm-multipath. Thus, this module is written for LUN-based failover.
+ */
+#include <linux/blkdev.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "dm.h"
+#include "dm-hw-handler.h"
+
+#define DM_MSG_PREFIX "multipath hp-sw"
+#define DM_HP_HWH_NAME "hp-sw"
+#define DM_HP_HWH_VER "0.0.3"
+
+struct hp_sw_context {
+ unsigned char sense[SCSI_SENSE_BUFFERSIZE];
+};
+
+/*
+ * hp_sw_end_io - Completion handler for HP path activation.
+ * @req: path activation request
+ * @error: scsi-ml error
+ *
+ * Check sense data, free request structure, and notify dm that
+ * pg initialization has completed.
+ *
+ * Context: scsi-ml softirq
+ *
+ * Possible optimizations
+ * 1. Actually check sense data for retryable error (e.g. NOT_READY)
+ */
+static void hp_sw_end_io(struct request *req, int error)
+{
+ struct dm_path *path = req->end_io_data;
+ unsigned err_flags = 0;
+
+ if (!error)
+ DMDEBUG("%s path activation command - success",
+ path->dev->name);
+ else {
+ DMWARN("%s path activation command - error=0x%x",
+ path->dev->name, error);
+ err_flags = MP_FAIL_PATH;
+ }
+
+ req->end_io_data = NULL;
+ __blk_put_request(req->q, req);
+ dm_pg_init_complete(path, err_flags);
+}
+
+/*
+ * hp_sw_get_request - Allocate an HP specific path activation request
+ * @path: path on which request will be sent (needed for request queue)
+ *
+ * The START command is used for path activation request.
+ * These arrays are controller-based failover, not LUN based.
+ * One START command issued to a single path will fail over all
+ * LUNs for the same controller.
+ *
+ * Possible optimizations
+ * 1. Make timeout configurable
+ * 2. Preallocate request
+ */
+static struct request *hp_sw_get_request(struct dm_path *path)
+{
+ struct request *req;
+ struct block_device *bdev = path->dev->bdev;
+ struct request_queue *q = bdev_get_queue(bdev);
+ struct hp_sw_context *h = path->hwhcontext;
+
+ req = blk_get_request(q, WRITE, GFP_NOIO);
+ if (!req)
+ goto out;
+
+ req->timeout = 60 * HZ;
+
+ req->errors = 0;
+ req->cmd_type = REQ_TYPE_BLOCK_PC;
+ req->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
+ req->end_io_data = path;
+ req->sense = h->sense;
+ memset(req->sense, 0, SCSI_SENSE_BUFFERSIZE);
+
+ memset(&req->cmd, 0, BLK_MAX_CDB);
+ req->cmd[0] = START_STOP;
+ req->cmd[4] = 1;
+ req->cmd_len = COMMAND_SIZE(req->cmd[0]);
+
+out:
+ return req;
+}
+
+/*
+ * hp_sw_pg_init - HP path activation implementation.
+ * @hwh: hardware handler specific data
+ * @bypassed: unused; is the path group bypassed? (see dm-mpath.c)
+ * @path: path to send initialization command
+ *
+ * Send an HP-specific path activation command on 'path'.
+ * Do not try to optimize in any way, just send the activation command.
+ * More than one path activation command may be sent to the same controller.
+ * This seems to work fine for basic failover support.
+ *
+ * Possible optimizations
+ * 1. Detect an in-progress activation request and avoid submitting another one
+ * 2. Model the controller and only send a single activation request at a time
+ * 3. Determine the state of a path before sending an activation request
+ *
+ * Context: kmpathd (see process_queued_ios() in dm-mpath.c)
+ */
+static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed,
+ struct dm_path *path)
+{
+ struct request *req;
+ struct hp_sw_context *h;
+
+ path->hwhcontext = hwh->context;
+ h = hwh->context;
+
+ req = hp_sw_get_request(path);
+ if (!req) {
+ DMERR("%s path activation command - allocation fail",
+ path->dev->name);
+ goto fail;
+ }
+
+ DMDEBUG("%s path activation command - sent", path->dev->name);
+
+ blk_execute_rq_nowait(req->q, NULL, req, 1, hp_sw_end_io);
+ return;
+
+fail:
+ dm_pg_init_complete(path, MP_FAIL_PATH);
+}
+
+static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv)
+{
+ struct hp_sw_context *h;
+
+ h = kmalloc(sizeof(*h), GFP_KERNEL);
+ if (!h)
+ return -ENOMEM;
+
+ hwh->context = h;
+
+ return 0;
+}
+
+static void hp_sw_destroy(struct hw_handler *hwh)
+{
+ struct hp_sw_context *h = hwh->context;
+
+ kfree(h);
+}
+
+static struct hw_handler_type hp_sw_hwh = {
+ .name = DM_HP_HWH_NAME,
+ .module = THIS_MODULE,
+ .create = hp_sw_create,
+ .destroy = hp_sw_destroy,
+ .pg_init = hp_sw_pg_init,
+};
+
+static int __init hp_sw_init(void)
+{
+ int r;
+
+ r = dm_register_hw_handler(&hp_sw_hwh);
+ if (r < 0)
+ DMERR("register failed %d", r);
+ else
+ DMINFO("version " DM_HP_HWH_VER " loaded");
+
+ return r;
+}
+
+static void __exit hp_sw_exit(void)
+{
+ int r;
+
+ r = dm_unregister_hw_handler(&hp_sw_hwh);
+ if (r < 0)
+ DMERR("unregister failed %d", r);
+}
+
+module_init(hp_sw_init);
+module_exit(hp_sw_exit);
+
+MODULE_DESCRIPTION("DM Multipath HP StorageWorks / FSC FibreCat (A/P) support");
+MODULE_AUTHOR("Mike Christie, Dave Wysochanski <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DM_HP_HWH_VER);
projects / linux-2.6 / commitdiff