[dm-devel] [2.6.24 PATCH 22/25] dm mpath: add hp handler
Alasdair G Kergon
agk at redhat.com
Fri Oct 12 17:23:05 UTC 2007
From: Dave Wysochanski <dwysocha at redhat.com>
This patch adds the most basic dm-multipath hardware support for the
HP active/passive arrays.
Signed-off-by: Dave Wysochanski <dwysocha at redhat.com>
Signed-off-by: Mike Christie <michaelc at cs.wisc.edu>
Acked-by: Chandra Seetharaman <sekharan at us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk at redhat.com>
---
drivers/md/Kconfig | 6 +
drivers/md/Makefile | 2
drivers/md/dm-mpath-hp-sw.c | 206 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 214 insertions(+)
Index: linux-2.6.23/drivers/md/Kconfig
===================================================================
--- linux-2.6.23.orig/drivers/md/Kconfig 2007-10-12 12:36:14.000000000 +0100
+++ linux-2.6.23/drivers/md/Kconfig 2007-10-12 15:03:29.000000000 +0100
@@ -267,6 +267,12 @@ config DM_MULTIPATH_RDAC
---help---
Multipath support for LSI/Engenio RDAC.
+config DM_MULTIPATH_HP
+ tristate "HP MSA multipath support (EXPERIMENTAL)"
+ depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Multipath support for HP MSA (Active/Passive) series hardware.
+
config DM_DELAY
tristate "I/O delaying target (EXPERIMENTAL)"
depends on BLK_DEV_DM && EXPERIMENTAL
Index: linux-2.6.23/drivers/md/Makefile
===================================================================
--- linux-2.6.23.orig/drivers/md/Makefile 2007-10-12 12:36:14.000000000 +0100
+++ linux-2.6.23/drivers/md/Makefile 2007-10-12 15:03:29.000000000 +0100
@@ -8,6 +8,7 @@ dm-multipath-objs := dm-hw-handler.o dm-
dm-snapshot-objs := dm-snap.o dm-exception-store.o
dm-mirror-objs := dm-log.o dm-raid1.o
dm-rdac-objs := dm-mpath-rdac.o
+dm-hp-sw-objs := dm-mpath-hp-sw.o
md-mod-objs := md.o bitmap.o
raid456-objs := raid5.o raid6algos.o raid6recov.o raid6tables.o \
raid6int1.o raid6int2.o raid6int4.o \
@@ -35,6 +36,7 @@ obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
obj-$(CONFIG_DM_DELAY) += dm-delay.o
obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o
obj-$(CONFIG_DM_MULTIPATH_EMC) += dm-emc.o
+obj-$(CONFIG_DM_MULTIPATH_HP) += dm-hp-sw.o
obj-$(CONFIG_DM_MULTIPATH_RDAC) += dm-rdac.o
obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
Index: linux-2.6.23/drivers/md/dm-mpath-hp-sw.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.23/drivers/md/dm-mpath-hp-sw.c 2007-10-12 15:03:29.000000000 +0100
@@ -0,0 +1,206 @@
+/*
+ * 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 at redhat.com>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DM_HP_HWH_VER);
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