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Re: [dm-devel] [RFC] HP storageworks-like hwhandler



On Fri, 2005-06-03 at 11:32, Mike Christie wrote:
> Christophe Varoqui wrote:
> > Hello,
> > 
> > I repackaged Dave Olien's scsi-start hwhandler to try to give it a wider audience.
> > It now compiles out-of-tree, and builds fine on RHEL4U1 kernel.
> > 
> > This hwhandler is targeted at a family of assymmetric arrays like HP StorageWorks and FSC FibreCat that take a START_STOP SCSI cmd as a sign of the host willing to initiate a LUN failover.
> > 
> > It would be good to have this code undusted and endorsed by HP ... before RHEL4U2 freezes.
> > Seems a good topic for the next conf call :/
> > 
> > You can find the tarball there :
> > http://christophe.varoqui.free.fr/multipath-tools/dm-scsi-start.tar.gz
> >
> 
> This looks like his old code which had several problems. I think he 
> fixed them up. Is there a new version?



This should do the same thing as Dave's code. It was modifiied from
my old patchset. The patch was built against 2.5.12-rc5. Since
I do not know any of the sense values, or specifics of the command,
or the HW or have the HW, it is pretty bare and only compile tested.
Since it does not use any of the new features in unstable I think it
should work against that patchset too.



diff -Naurp linux-2.6.12-rc5.orig//drivers/md/dm-hp-sw.c linux-2.6.12-rc5/drivers/md/dm-hp-sw.c
--- linux-2.6.12-rc5.orig//drivers/md/dm-hp-sw.c	1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.12-rc5/drivers/md/dm-hp-sw.c	2005-06-03 17:37:44.000000000 -0700
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2005 Mike Christie, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ *
+ * Basic, very basic, support for HP StorageWorks and FSC FibreCat
+ */
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "dm.h"
+#include "dm-hw-handler.h"
+
+struct hp_sw_handler {
+	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
+};
+
+static void hp_sw_endio(struct request *rq)
+{
+	struct path *path = rq->end_io_data;
+
+	/*
+	 * TODO: something.. we have the sense and scsi bytes
+	 */
+	if (rq->errors) {
+		DMINFO("hp_sw: START_STOP completed %d", rq->errors);
+		dm_pg_init_complete(path, MP_FAIL_PATH);
+	} else
+		dm_pg_init_complete(path, 0);
+
+	blk_put_request(rq);
+}
+
+static struct request *hp_sw_get_request(struct hp_sw_handler *h,
+					struct path *path)
+{
+	struct request *rq;
+	struct block_device *bdev = path->dev->bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	rq = blk_get_request(q, READ, __GFP_WAIT);
+	if (!rq)
+		return NULL;
+
+	rq->end_io = hp_sw_endio;
+	rq->end_io_data = path;
+	rq->rq_disk = bdev->bd_contains->bd_disk;
+	rq->sense = h->sense;
+	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+	rq->sense_len = 0;
+	/*
+	 * TODO: make me configurable
+	 */
+	rq->timeout = 30;
+	rq->flags |= (REQ_BLOCK_PC | REQ_FAILFAST | REQ_NOMERGE);
+
+	memset(&rq->cmd, 0, BLK_MAX_CDB);
+	rq->cmd[0] = START_STOP;
+	/* Start spin cycle */
+	rq->cmd[4] = 1;
+	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+
+	return rq;
+}
+
+static void hp_sw_pg_init(struct hw_handler *hwh, unsigned bypassed,
+			   struct path *path)
+{
+	struct request *rq;
+	struct request_queue *q = bdev_get_queue(path->dev->bdev);
+
+	/*
+	 * We can either blindly init the pg (then look at the sense),
+	 * or we can send some commands to get the state here (then
+	 * possibly send the fo cmnd), or we can also have the
+	 * initial state passed into us and then get an update here.
+	 */
+	if (!q) {
+		DMERR("hp_sw: no queue!");
+		goto fail_path;
+	}
+
+	if (blk_get_queue(q))
+		goto fail_path;
+
+	rq = hp_sw_get_request(hwh->context, path);
+	if (!rq) {
+		DMERR("hp_sw: could not allocate request for START_STOP");
+		goto rel_queue;
+	}
+
+	DMINFO("hp_sw: queueing START_STOP command");
+	elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
+	blk_put_queue(q);
+	return;
+
+rel_queue:
+	blk_put_queue(q);
+fail_path:
+	dm_pg_init_complete(path, MP_FAIL_PATH);
+}
+
+static int hp_sw_create(struct hw_handler *hwh, unsigned argc, char **argv)
+{
+	struct hp_sw_handler *h;
+
+	h = kmalloc(sizeof(*h), GFP_KERNEL);
+	if (!h) {
+		DMERR("hp_sw: could not allocate hw_handler");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void hp_sw_destroy(struct hw_handler *hwh)
+{
+	struct hp_sw_handler *h = hwh->context;
+
+	kfree(h);
+	hwh->context = NULL;
+}
+
+static struct hw_handler_type hp_sw_hwh = {
+	.name = "hp_sw",
+	.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("hp_sw: register failed %d", r);
+
+	DMINFO("hp_sw version 0.1 loaded");
+
+	return r;
+}
+
+static void __exit hp_sw_exit(void)
+{
+	int r;
+
+	r = dm_unregister_hw_handler(&hp_sw_hwh);
+	if (r < 0)
+		DMERR("hp_sw: unregister failed %d", r);
+}
+
+module_init(hp_sw_init);
+module_exit(hp_sw_exit);
+
+MODULE_DESCRIPTION("HP StorageWorks and FSC FibreCat support for dm-multipath");
+MODULE_AUTHOR("Mike Christie <michaelc cs wisc edu>");
+MODULE_LICENSE("GPL");
diff -Naurp linux-2.6.12-rc5.orig//drivers/md/Kconfig linux-2.6.12-rc5/drivers/md/Kconfig
--- linux-2.6.12-rc5.orig//drivers/md/Kconfig	2005-05-24 20:31:20.000000000 -0700
+++ linux-2.6.12-rc5/drivers/md/Kconfig	2005-06-03 16:48:59.000000000 -0700
@@ -236,5 +236,14 @@ config DM_MULTIPATH_EMC
 	---help---
 	  Multipath support for EMC CX/AX series hardware.
 
+config DM_MULTIPATH_HP_SW
+	tristate "HP StorageWorks and FSC FibreCat (EXPERIMENTAL)"
+	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
+	---help---
+	  Multipath support for HP StorageWorks and FSC FibreCat.
+          This was created with no knowledge of the HW other than
+          that it uses a START_STOP command for failover so it
+          is marked EXPERIMENTAL.
+
 endmenu
 
diff -Naurp linux-2.6.12-rc5.orig//drivers/md/Makefile linux-2.6.12-rc5/drivers/md/Makefile
--- linux-2.6.12-rc5.orig//drivers/md/Makefile	2005-05-24 20:31:20.000000000 -0700
+++ linux-2.6.12-rc5/drivers/md/Makefile	2005-06-03 16:46:16.000000000 -0700
@@ -33,6 +33,7 @@ obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
 obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o
 obj-$(CONFIG_DM_MULTIPATH_EMC)	+= dm-emc.o
+obj-$(CONFIG_DM_MULTIPATH_HP_SW) += dm-hp-sw.o
 obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
 obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o
 obj-$(CONFIG_DM_ZERO)		+= dm-zero.o






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