hp-sw-init.patch - this is a priority-group module for the HP storage works
device. I have only tested this with scsi_debug, so I know that the start_stop
is making its way to scsi and is returning safely.
diff -Naurp linux-2.6.7-rc2/drivers/md/dm-pg-hp-sw.c linux-2.6.7-rc2-pg/drivers/md/dm-pg-hp-sw.c
--- linux-2.6.7-rc2/drivers/md/dm-pg-hp-sw.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.7-rc2-pg/drivers/md/dm-pg-hp-sw.c 2004-06-04 22:31:50.882789752 -0700
@@ -0,0 +1,330 @@
+/*
+ * Basic priority group for HP Storage Works to show how to
+ * send a failover command. DM is bio based but in here we stick
+ * in the request and SCSI stuff.
+ *
+ * We are also just failing over per lun. More logic could
+ * be added to also failover at the controller level.
+ */
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "dm.h"
+#include "dm-priority-group.h"
+
+
+/* FIXME: get rid of this */
+#define PG_FAIL_COUNT 1
+
+struct path_info {
+ struct list_head list;
+ struct path *path;
+ unsigned fail_count;
+};
+
+/*
+ * bleh - we do not need this. put some sort of private memeber on the
+ * path struct along with nice accessor fns. This is only used in
+ * non critical code paths though.
+ */
+static struct path_info *path_lookup(struct list_head *head, struct path *p)
+{
+ struct path_info *pi;
+
+ list_for_each_entry (pi, head, list)
+ if (pi->path == p)
+ return pi;
+
+ return NULL;
+}
+
+struct pgroup {
+ struct priority_group *pg;
+
+ /* failover command */
+ struct request rq;
+ char sense[SCSI_SENSE_BUFFERSIZE];
+
+ spinlock_t path_lock;
+
+ struct list_head valid_paths;
+ struct list_head invalid_paths;
+};
+
+static struct pgroup *alloc_pgroup(void)
+{
+ struct pgroup *pgroup = kmalloc(sizeof(*pgroup), GFP_KERNEL);
+
+ if (pgroup) {
+ memset(pgroup, 0, sizeof(*pgroup));
+ INIT_LIST_HEAD(&pgroup->valid_paths);
+ INIT_LIST_HEAD(&pgroup->invalid_paths);
+ pgroup->path_lock = SPIN_LOCK_UNLOCKED;
+ }
+
+ return pgroup;
+}
+
+static int hpsw_ctr(struct priority_group *pg)
+{
+ struct pgroup *pgroup;
+
+ pgroup = alloc_pgroup();
+ if (!pgroup)
+ return -ENOMEM;
+
+ pgroup->pg = pg;
+ pg->context = pgroup;
+ return 0;
+}
+
+static void free_paths(struct list_head *paths)
+{
+ struct path_info *pi, *next;
+
+ list_for_each_entry_safe (pi, next, paths, list) {
+ list_del(&pi->list);
+ kfree(pi);
+ }
+}
+
+static void hpsw_dtr(struct priority_group *pg)
+{
+ struct pgroup *pgroup = (struct pgroup *)pg->context;
+ free_paths(&pgroup->valid_paths);
+ free_paths(&pgroup->invalid_paths);
+ kfree(pgroup);
+}
+
+static int hpsw_add_path(struct priority_group *pg, struct path *path,
+ int argc, char **argv, char **error)
+{
+ struct pgroup *pgroup= (struct pgroup *) pg->context;
+ struct path_info *pi;
+
+ if (argc != 0) {
+ *error = "hp-storage-works: incorrect number of arguments";
+ return -EINVAL;
+ }
+
+ pi = kmalloc(sizeof(*pi), GFP_KERNEL);
+ if (!pi) {
+ *error = "hp-storage-works: Error allocating path context";
+ return -ENOMEM;
+ }
+
+ pi->fail_count = 0;
+ pi->path = path;
+
+ spin_lock(&pgroup->path_lock);
+ list_add_tail(&pi->list, &pgroup->valid_paths);
+ spin_unlock(&pgroup->path_lock);
+
+ return 0;
+}
+
+static int hpsw_update_path(struct priority_group *pg,
+ struct path *path, int status)
+{
+ unsigned long flags;
+ int r = 0;
+ struct path_info *pi;
+ struct pgroup *pgroup = (struct pgroup *) pg->context;
+
+ spin_lock_irqsave(&pgroup->path_lock, flags);
+
+ if (status) {
+ pi = path_lookup(&pgroup->valid_paths, path);
+ if (!pi) {
+ /*
+ * This can happen if a path was marked as
+ * failed by the init function.
+ * We did not tell the ps that the path
+ * was failed becuase we wanted to give the
+ * path an extra chance.
+ */
+ r = 1;
+ goto done;
+ }
+
+ if (++pi->fail_count == PG_FAIL_COUNT) {
+ list_move(&pi->list, &pgroup->invalid_paths);
+ r = 1;
+ }
+
+ } else {
+ pi = path_lookup(&pgroup->invalid_paths, path);
+ if (!pi)
+ goto done;
+
+ list_move(&pi->list, &pgroup->valid_paths);
+ }
+
+ done:
+ spin_unlock_irqrestore(&pgroup->path_lock, flags);
+
+ return r;
+}
+
+
+static int hpsw_status(struct priority_group *pg, struct path *path,
+ status_type_t type, char *result,
+ unsigned int maxlen)
+{
+ unsigned long flags;
+ int failed = 0;
+ struct path_info *pi;
+ int sz = 0;
+ struct pgroup *pgroup = (struct pgroup *) pg->context;
+
+ if (type == STATUSTYPE_TABLE)
+ return 0;
+
+ spin_lock_irqsave(&pgroup->path_lock, flags);
+
+ pi = path_lookup(&pgroup->valid_paths, path);
+ if (!pi) {
+ failed = 1;
+ pi = path_lookup(&pgroup->invalid_paths, path);
+ }
+
+ sz = scnprintf(result, maxlen, "%s %u ", failed ? "F" : "A",
+ pi->fail_count);
+
+ spin_unlock_irqrestore(&pgroup->path_lock, flags);
+
+ return sz;
+}
+
+static int hpsw_init(struct priority_group *pg);
+
+#define rq_to_pgroup(__rq) container_of((__rq), struct pgroup, rq)
+
+static void hpsw_failover_cmd_done(struct request *rq)
+{
+ struct pgroup *pgroup = rq_to_pgroup(rq);
+ struct priority_group *pg = pgroup->pg;
+ int err = DM_PG_SUCCESS;
+
+ /* let's try another path (you can also look at the sense) */
+ if (rq->errors)
+ err = hpsw_init(pg);
+
+ /*
+ * if we are retrying the command on another path don't
+ * signal dm-mpath yet.
+ */
+ if (err != DM_PG_INITIALIZING)
+ dm_pg_init_complete(pg, err);
+}
+
+/* ??? */
+#define HPSW_FAILOVER_TIMEOUT (60 * HZ)
+
+static int hpsw_insert_cmd(struct priority_group *pg, struct path_info *pi)
+{
+ struct pgroup *pgroup = (struct pgroup *) pg->context;
+ struct request *rq = &pgroup->rq;
+ request_queue_t *q;
+ char *sense = pgroup->sense;
+ struct block_device *bdev;
+
+ bdev = dm_path_to_bdev(pi->path);
+ q = bdev_get_queue(bdev);
+ if (!q)
+ return -EINVAL;
+
+ memset(rq, 0, sizeof(*rq));
+ rq->flags = READ;
+ rq->rq_status = RQ_ACTIVE;
+ rq->ref_count = 1;
+ rq->q = q;
+ rq->errors = 0;
+ rq->bio = rq->biotail = NULL;
+ rq->buffer = NULL;
+ rq->ref_count = 2;
+ rq->rl = NULL;
+ rq->end_request = NULL;
+ rq->waiting = NULL;
+ rq->special = NULL;
+
+ memset(sense, 0, sizeof(SCSI_SENSE_BUFFERSIZE));
+ rq->sense = sense;
+ rq->sense_len = 0;
+
+ rq->cmd[0] = START_STOP;
+ rq->cmd[1] = 1; /* return immed or wait ??? */
+ rq->cmd[4] = 1; /* spin up */
+ rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+
+ rq->data = NULL;
+ rq->data_len = 0;
+
+ rq->flags |= REQ_NOMERGE | REQ_BLOCK_PC | REQ_FAILFAST;
+
+ rq->rq_disk = bdev->bd_contains->bd_disk;
+ rq->timeout = HPSW_FAILOVER_TIMEOUT;
+ rq->end_request = hpsw_failover_cmd_done;
+
+ elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
+
+ return 0;
+}
+
+static int hpsw_init(struct priority_group *pg)
+{
+ struct path_info *pi;
+ struct pgroup *pgroup = (struct pgroup *) pg->context;
+ int err = DM_PG_FAILED;
+
+ while (!list_empty(&pgroup->valid_paths)) {
+ pi = list_entry(pgroup->valid_paths.next,
+ struct path_info, list);
+
+ if (hpsw_insert_cmd(pg, pi))
+ list_move(&pi->list, &pgroup->invalid_paths);
+ else {
+ err = DM_PG_INITIALIZING;
+ break;
+ }
+ }
+
+ return err;
+}
+
+static struct priority_group_type hpsw_pg = {
+ .name = "hp-storage-works",
+ .module = THIS_MODULE,
+
+ .ctr = hpsw_ctr,
+ .dtr = hpsw_dtr,
+ .init = hpsw_init,
+ .add_path = hpsw_add_path,
+ .update_path = hpsw_update_path,
+ .status = hpsw_status,
+};
+
+static int __init init_hpsw(void)
+{
+ return dm_register_priority_group_type(&hpsw_pg);
+}
+
+static void __exit exit_hpsw(void)
+{
+ dm_unregister_priority_group_type(&hpsw_pg);
+}
+
+module_init(init_hpsw);
+module_exit(exit_hpsw);
+
+MODULE_DESCRIPTION("Manual Failover for HP Storage Works");
+MODULE_AUTHOR("Mike Christie");
+MODULE_LICENSE("GPL");
diff -Naurp linux-2.6.7-rc2/drivers/md/Kconfig linux-2.6.7-rc2-pg/drivers/md/Kconfig
--- linux-2.6.7-rc2/drivers/md/Kconfig 2004-06-04 03:52:23.000000000 -0700
+++ linux-2.6.7-rc2-pg/drivers/md/Kconfig 2004-06-04 22:31:44.518038122 -0700
@@ -206,6 +206,12 @@ config DM_MULTIPATH
---help---
Allow volume managers to support multipath hardware.
+config DM_PG_HPSW
+ tristate "DM Multipath HP Storage Works (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Manual failover support for HP Storage Works.
+
config DM_FLAKEY
tristate "Flakey target (EXPERIMENTAL)"
depends on BLK_DEV_DM && EXPERIMENTAL
diff -Naurp linux-2.6.7-rc2/drivers/md/Makefile linux-2.6.7-rc2-pg/drivers/md/Makefile
--- linux-2.6.7-rc2/drivers/md/Makefile 2004-06-04 04:04:17.000000000 -0700
+++ linux-2.6.7-rc2-pg/drivers/md/Makefile 2004-06-04 22:31:41.202181278 -0700
@@ -28,6 +28,7 @@ obj-$(CONFIG_BLK_DEV_MD) += md.o
obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o
+obj-$(CONFIG_DM_PG_HPSW) += dm-pg-hp-sw.o
obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
obj-$(CONFIG_DM_FLAKEY) += dm-flakey.o
