[PATCH] device-mapper: multipath hardware handler for EMC

Alasdair G Kergon
2005-02-11T17:30:43Z

Outline Hardware Handler for EMC CLARiiON AX/CX-series.

Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
From: Lars Marowsky-Bree <lmb@suse.de>
--- diff/drivers/md/Kconfig 2005-02-09 14:41:52.000000000 +0000
+++ source/drivers/md/Kconfig 2005-02-09 14:42:24.000000000 +0000
@@ -233,5 +233,11 @@
---help---
Allow volume managers to support multipath hardware.

+config DM_MULTIPATH_EMC
+ tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
+ depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Multipath support for EMC CX/AX series hardware.
+
endmenu

--- diff/drivers/md/Makefile 2005-02-09 14:42:12.000000000 +0000
+++ source/drivers/md/Makefile 2005-02-09 14:42:24.000000000 +0000
@@ -32,6 +32,7 @@
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-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
obj-$(CONFIG_DM_ZERO) += dm-zero.o
--- diff/drivers/md/dm-emc.c 1970-01-01 01:00:00.000000000 +0100
+++ source/drivers/md/dm-emc.c 2005-02-09 14:42:24.000000000 +0000
@@ -0,0 +1,363 @@
+/*
+ * Copyright (C) 2004 SUSE LINUX Products GmbH. All rights reserved.
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ *
+ * Multipath support for EMC CLARiiON AX/CX-series hardware.
+ */
+
+#include "dm.h"
+#include "dm-hw-handler.h"
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+
+struct emc_handler {
+ spinlock_t lock;
+
+ /* Whether we should send the short trespass command (FC-series)
+ * or the long version (default for AX/CX CLARiiON arrays). */
+ unsigned short_trespass;
+ /* Whether or not to honor SCSI reservations when initiating a
+ * switch-over. Default: Don't. */
+ unsigned hr;
+
+ unsigned char sense[SCSI_SENSE_BUFFERSIZE];
+};
+
+#define TRESPASS_PAGE 0x22
+#define EMC_FAILOVER_TIMEOUT (60 * HZ)
+
+/* Code borrowed from dm-lsi-rdac by Mike Christie */
+
+static inline void free_bio(struct bio *bio)
+{
+ __free_page(bio->bi_io_vec[0].bv_page);
+ bio_put(bio);
+}
+
+static int emc_endio(struct bio *bio, unsigned int bytes_done, int error)
+{
+ struct path *path = bio->bi_private;
+
+ if (bio->bi_size)
+ return 1;
+
+ /* We also need to look at the sense keys here whether or not to
+ * switch to the next PG etc.
+ *
+ * For now simple logic: either it works or it doesn't.
+ */
+ if (error)
+ dm_pg_init_complete(path, MP_FAIL_PATH);
+ else
+ dm_pg_init_complete(path, 0);
+
+ /* request is freed in block layer */
+ free_bio(bio);
+
+ return 0;
+}
+
+static struct bio *get_failover_bio(struct path *path, unsigned data_size)
+{
+ struct bio *bio;
+ struct page *page;
+
+ bio = bio_alloc(GFP_ATOMIC, 1);
+ if (!bio) {
+ DMERR("dm-emc: get_failover_bio: bio_alloc() failed.");
+ return NULL;
+ }
+
+ bio->bi_rw |= (1 << BIO_RW);
+ bio->bi_bdev = path->dev->bdev;
+ bio->bi_sector = 0;
+ bio->bi_private = path;
+ bio->bi_end_io = emc_endio;
+
+ page = alloc_page(GFP_ATOMIC);
+ if (!page) {
+ DMERR("dm-emc: get_failover_bio: alloc_page() failed.");
+ bio_put(bio);
+ return NULL;
+ }
+
+ if (bio_add_page(bio, page, data_size, 0) != data_size) {
+ DMERR("dm-emc: get_failover_bio: alloc_page() failed.");
+ __free_page(page);
+ bio_put(bio);
+ return NULL;
+ }
+
+ return bio;
+}
+
+static struct request *get_failover_req(struct emc_handler *h,
+ struct bio *bio, struct path *path)
+{
+ struct request *rq;
+ struct block_device *bdev = bio->bi_bdev;
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ /* FIXME: Figure out why it fails with GFP_ATOMIC. */
+ rq = blk_get_request(q, WRITE, __GFP_WAIT);
+ if (!rq) {
+ DMERR("dm-emc: get_failover_req: blk_get_request failed");
+ return NULL;
+ }
+
+ rq->bio = rq->biotail = bio;
+ blk_rq_bio_prep(q, rq, bio);
+
+ rq->rq_disk = bdev->bd_contains->bd_disk;
+
+ /* bio backed don't set data */
+ rq->buffer = rq->data = NULL;
+ /* rq data_len used for pc cmd's request_bufflen */
+ rq->data_len = bio->bi_size;
+
+ rq->sense = h->sense;
+ memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+ rq->sense_len = 0;
+
+ memset(&rq->cmd, 0, BLK_MAX_CDB);
+
+ rq->timeout = EMC_FAILOVER_TIMEOUT;
+ rq->flags |= (REQ_BLOCK_PC | REQ_FAILFAST | REQ_NOMERGE);
+
+ return rq;
+}
+
+static struct request *emc_trespass_get(struct emc_handler *h,
+ struct path *path)
+{
+ struct bio *bio;
+ struct request *rq;
+ unsigned char *page22;
+ unsigned char long_trespass_pg[] = {
+ 0, 0, 0, 0,
+ TRESPASS_PAGE, /* Page code */
+ 0x09, /* Page length - 2 */
+ h->hr ? 0x01 : 0x81, /* Trespass code + Honor reservation bit */
+ 0xff, 0xff, /* Trespass target */
+ 0, 0, 0, 0, 0, 0 /* Reserved bytes / unknown */
+ };
+ unsigned char short_trespass_pg[] = {
+ 0, 0, 0, 0,
+ TRESPASS_PAGE, /* Page code */
+ 0x02, /* Page length - 2 */
+ h->hr ? 0x01 : 0x81, /* Trespass code + Honor reservation bit */
+ 0xff, /* Trespass target */
+ };
+ unsigned data_size = h->short_trespass ? sizeof(short_trespass_pg) :
+ sizeof(long_trespass_pg);
+
+ /* get bio backing */
+ if (data_size > PAGE_SIZE)
+ /* this should never happen */
+ return NULL;
+
+ bio = get_failover_bio(path, data_size);
+ if (!bio) {
+ DMERR("dm-emc: emc_trespass_get: no bio");
+ return NULL;
+ }
+
+ page22 = (unsigned char *)bio_data(bio);
+ memset(page22, 0, data_size);
+
+ if (h->short_trespass) {
+ memcpy(page22, short_trespass_pg, data_size);
+ } else {
+ memcpy(page22, long_trespass_pg, data_size);
+ }
+
+ /* get request for block layer packet command */
+ rq = get_failover_req(h, bio, path);
+ if (!rq) {
+ DMERR("dm-emc: emc_trespass_get: no rq");
+ free_bio(bio);
+ return NULL;
+ }
+
+ /* Prepare the command. */
+ rq->cmd[0] = MODE_SELECT;
+ rq->cmd[1] = 0x10;
+ rq->cmd[4] = data_size;
+ rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+
+ return rq;
+}
+
+static void emc_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) {
+ DMINFO("dm-emc: emc_pg_init: no queue");
+ goto fail_path;
+ }
+
+ /* FIXME: The request should be pre-allocated. */
+ rq = emc_trespass_get(hwh->context, path);
+ if (!rq) {
+ DMERR("dm-emc: emc_pg_init: no rq");
+ goto fail_path;
+ }
+
+ DMINFO("dm-emc: emc_pg_init: sending switch-over command");
+ elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 1);
+ return;
+
+fail_path:
+ dm_pg_init_complete(path, MP_FAIL_PATH);
+}
+
+static struct emc_handler *alloc_emc_handler(void)
+{
+ struct emc_handler *h = kmalloc(sizeof(*h), GFP_KERNEL);
+
+ if (h) {
+ h->lock = SPIN_LOCK_UNLOCKED;
+ }
+
+ return h;
+}
+
+static int emc_ctr(struct hw_handler *hwh, unsigned argc, char **argv)
+{
+ struct emc_handler *h;
+ unsigned hr, short_trespass;
+
+ if (argc == 0) {
+ /* No arguments: use defaults */
+ hr = 0;
+ short_trespass = 0;
+ } else if (argc != 2) {
+ DMWARN("dm-emc hwhandler: incorrect number of arguments");
+ return -EINVAL;
+ } else {
+ if ((sscanf(argv[0], "%u", &short_trespass) != 1)
+ || (short_trespass > 1)) {
+ DMWARN("dm-emc: invalid trespass mode selected");
+ return -EINVAL;
+ }
+
+ if ((sscanf(argv[1], "%u", &hr) != 1)
+ || (hr > 1)) {
+ DMWARN("dm-emc: invalid honor reservation flag selected");
+ return -EINVAL;
+ }
+ }
+
+ h = alloc_emc_handler();
+ if (!h)
+ return -ENOMEM;
+
+ memset(h, 0, sizeof(*h));
+
+ hwh->context = h;
+
+ if ((h->short_trespass = short_trespass))
+ DMWARN("dm-emc: short trespass command will be send");
+ else
+ DMWARN("dm-emc: long trespass command will be send");
+
+ if ((h->hr = hr))
+ DMWARN("dm-emc: honor reservation bit will be set");
+ else
+ DMWARN("dm-emc: honor reservation bit will not be set (default)");
+
+ return 0;
+}
+
+static void emc_dtr(struct hw_handler *hwh)
+{
+ struct emc_handler *h = (struct emc_handler *) hwh->context;
+
+ kfree(h);
+ hwh->context = NULL;
+}
+
+static unsigned emc_err(struct hw_handler *hwh, struct bio *bio)
+{
+ /* FIXME: Patch from axboe still missing */
+#if 0
+ int sense;
+
+ if (bio->bi_error & BIO_SENSE) {
+ sense = bio->bi_error & 0xffffff; /* sense key / asc / ascq */
+
+ if (sense == 0x020403) {
+ /* LUN Not Ready - Manual Intervention Required
+ * indicates this is a passive path.
+ *
+ * FIXME: However, if this is seen and EVPD C0
+ * indicates that this is due to a NDU in
+ * progress, we should set FAIL_PATH too.
+ * This indicates we might have to do a SCSI
+ * inquiry in the end_io path. Ugh. */
+ return MP_BYPASS_PG | MP_RETRY_IO;
+ } else if (sense == 0x052501) {
+ /* An array based copy is in progress. Do not
+ * fail the path, do not bypass to another PG,
+ * do not retry. Fail the IO immediately.
+ * (Actually this is the same conclusion as in
+ * the default handler, but lets make sure.) */
+ return 0;
+ } else if (sense == 0x062900) {
+ /* Unit Attention Code. This is the first IO
+ * to the new path, so just retry. */
+ return MP_RETRY_IO;
+ }
+ }
+#endif
+
+ /* Try default handler */
+ return dm_scsi_err_handler(hwh, bio);
+}
+
+static struct hw_handler_type emc_hwh = {
+ .name = "emc",
+ .module = THIS_MODULE,
+ .ctr = emc_ctr,
+ .dtr = emc_dtr,
+ .pg_init = emc_pg_init,
+ .err = emc_err,
+};
+
+static int __init dm_emc_init(void)
+{
+ int r = dm_register_hw_handler(&emc_hwh);
+
+ if (r < 0)
+ DMERR("emc: register failed %d", r);
+
+ DMINFO("dm-emc version 0.0.3 loaded");
+
+ return r;
+}
+
+static void __exit dm_emc_exit(void)
+{
+ int r = dm_unregister_hw_handler(&emc_hwh);
+
+ if (r < 0)
+ DMERR("emc: unregister failed %d", r);
+}
+
+module_init(dm_emc_init);
+module_exit(dm_emc_exit);
+
+MODULE_DESCRIPTION(DM_NAME " EMC CX/AX/FC-family multipath");
+MODULE_AUTHOR("Lars Marowsky-Bree <lmb@suse.de>");
+MODULE_LICENSE("GPL");