Attachment 314159 Details for Bug 438761 – Changes in dm layer to use SCSI Hardware Handler

Changes in dm layer to use SCSI Hardware Handler

05-use_scsi_dh_in_multipath.patch (text/plain), 9.76 KB, created by IBM Bug Proxy on 2008-08-13 00:51:28 UTC

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Creator: IBM Bug Proxy

Created: 2008-08-13 00:51:28 UTC

Size: 9.76 KB

patch

obsolete

>Subject: scsi_dh: Use SCSI device handler in dm-multipath
>
>From: Chandra Seetharaman <sekharan@us.ibm.com>
>
>This patch converts dm-mpath to use scsi device handlers instead of 
>dm's hardware handlers.
>
>This patch does not add any new functionality. Old behaviors remain and
>userspace tools work as is except that arguments supplied with hardware
>handler are ignored.
>
>One behavioral exception is: Activation of a path is synchronous in this
>patch, opposed to the older behavior of being asynchronous (changed in
>patch 07: scsi_dh: Add a single threaded workqueue for initializing a path)
>
>Note: There is no need to get a reference for the device handler module
>(as it was done in the dm hardware handler case) here as the reference
>is held when the device was first found. Instead we check and make sure
>that support for the specified device is present at table load time.
>
>Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
>Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
>---
> drivers/md/Kconfig    |    1 	1 +	0 -	0 !
> drivers/md/dm-mpath.c |  226 	111 +	115 -	0 !
> 2 files changed, 112 insertions(+), 115 deletions(-)
>
>Index: linux-2.6.18.ppc64/drivers/md/dm-mpath.c
>===================================================================
>--- linux-2.6.18.ppc64.orig/drivers/md/dm-mpath.c
>+++ linux-2.6.18.ppc64/drivers/md/dm-mpath.c
>@@ -20,6 +20,7 @@
> #include <linux/slab.h>
> #include <linux/time.h>
> #include <linux/workqueue.h>
>+#include <scsi/scsi_dh.h>
> #include <asm/atomic.h>
> 
> #define DM_MSG_PREFIX "multipath"
>@@ -61,7 +62,7 @@ struct multipath {
> 
> 	spinlock_t lock;
> 
>-	struct hw_handler hw_handler;
>+	const char *hw_handler_name;
> 	unsigned nr_priority_groups;
> 	struct list_head priority_groups;
> 	unsigned pg_init_required;	/* pg_init needs calling? */
>@@ -109,6 +110,7 @@ static kmem_cache_t *_mpio_cache;
> struct workqueue_struct *kmultipathd;
> static void process_queued_ios(void *data);
> static void trigger_event(void *data);
>+static void pg_init_done(struct path *, int);
> 
> 
> /*-----------------------------------------------
>@@ -149,9 +151,12 @@ static struct priority_group *alloc_prio
> static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
> {
> 	struct pgpath *pgpath, *tmp;
>+	struct multipath *m = (struct multipath *) ti->private;
> 
> 	list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
> 		list_del(&pgpath->list);
>+		if (m->hw_handler_name)
>+			scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev));
> 		dm_put_device(ti, pgpath->path.dev);
> 		free_pgpath(pgpath);
> 	}
>@@ -196,18 +201,13 @@ static struct multipath *alloc_multipath
> static void free_multipath(struct multipath *m)
> {
> 	struct priority_group *pg, *tmp;
>-	struct hw_handler *hwh = &m->hw_handler;
> 
> 	list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
> 		list_del(&pg->list);
> 		free_priority_group(pg, m->ti);
> 	}
> 
>-	if (hwh->type) {
>-		hwh->type->destroy(hwh);
>-		dm_put_hw_handler(hwh->type);
>-	}
>-
>+	kfree(m->hw_handler_name);
> 	mempool_destroy(m->mpio_pool);
> 	kfree(m);
> }
>@@ -219,12 +219,10 @@ static void free_multipath(struct multip
> 
> static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
> {
>-	struct hw_handler *hwh = &m->hw_handler;
>-
> 	m->current_pg = pgpath->pg;
> 
> 	/* Must we initialise the PG first, and queue I/O till it's ready? */
>-	if (hwh->type && hwh->type->pg_init) {
>+	if (m->hw_handler_name) {
> 		m->pg_init_required = 1;
> 		m->queue_io = 1;
> 	} else {
>@@ -404,7 +402,6 @@ static void dispatch_queued_ios(struct m
> static void process_queued_ios(void *data)
> {
> 	struct multipath *m = (struct multipath *) data;
>-	struct hw_handler *hwh = &m->hw_handler;
> 	struct pgpath *pgpath = NULL;
> 	unsigned init_required = 0, must_queue = 1;
> 	unsigned long flags;
>@@ -433,8 +430,11 @@ static void process_queued_ios(void *dat
> out:
> 	spin_unlock_irqrestore(&m->lock, flags);
> 
>-	if (init_required)
>-		hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path);
>+	if (init_required) {
>+		struct path *path = &pgpath->path;
>+		int ret = scsi_dh_activate(bdev_get_queue(path->dev->bdev));
>+		pg_init_done(path, ret);
>+	}
> 
> 	if (!must_queue)
> 		dispatch_queued_ios(m);
>@@ -545,6 +545,7 @@ static struct pgpath *parse_path(struct 
> {
> 	int r;
> 	struct pgpath *p;
>+	struct multipath *m = (struct multipath *) ti->private;
> 
> 	/* we need at least a path arg */
> 	if (as->argc < 1) {
>@@ -563,6 +564,15 @@ static struct pgpath *parse_path(struct 
> 		goto bad;
> 	}
> 
>+	if (m->hw_handler_name) {
>+		r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev),
>+				   m->hw_handler_name);
>+		if (r < 0) {
>+			dm_put_device(ti, p->path.dev);
>+			goto bad;
>+		}
>+	}
>+
> 	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
> 	if (r) {
> 		dm_put_device(ti, p->path.dev);
>@@ -647,35 +657,27 @@ static struct priority_group *parse_prio
> static int parse_hw_handler(struct arg_set *as, struct multipath *m,
> 			    struct dm_target *ti)
> {
>-	int r;
>-	struct hw_handler_type *hwht;
> 	unsigned hw_argc;
> 
> 	static struct param _params[] = {
> 		{0, 1024, "invalid number of hardware handler args"},
> 	};
> 
>-	r = read_param(_params, shift(as), &hw_argc, &ti->error);
>-	if (r)
>+	if (read_param(_params, shift(as), &hw_argc, &ti->error))
> 		return -EINVAL;
> 
> 	if (!hw_argc)
> 		return 0;
> 
>-	hwht = dm_get_hw_handler(shift(as));
>-	if (!hwht) {
>+	m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
>+	request_module("scsi_dh_%s", m->hw_handler_name);
>+	if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
> 		ti->error = "unknown hardware handler type";
>+		kfree(m->hw_handler_name);
>+		m->hw_handler_name = NULL;
> 		return -EINVAL;
> 	}
> 
>-	r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
>-	if (r) {
>-		dm_put_hw_handler(hwht);
>-		ti->error = "hardware handler constructor failed";
>-		return r;
>-	}
>-
>-	m->hw_handler.type = hwht;
> 	consume(as, hw_argc - 1);
> 
> 	return 0;
>@@ -749,6 +751,7 @@ static int multipath_ctr(struct dm_targe
> 	}
> 
> 	m->ti = ti;
>+	ti->private = m;
> 
> 	r = parse_features(&as, m, ti);
> 	if (r)
>@@ -790,8 +793,6 @@ static int multipath_ctr(struct dm_targe
> 		goto bad;
> 	}
> 
>-	ti->private = m;
>-
> 	return 0;
> 
>  bad:
>@@ -1061,14 +1062,74 @@ void dm_pg_init_complete(struct path *pa
> 	spin_unlock_irqrestore(&m->lock, flags);
> }
> 
>+static void pg_init_done(struct path *path, int errors)
>+{
>+	struct pgpath *pgpath = path_to_pgpath(path);
>+	struct priority_group *pg = pgpath->pg;
>+	struct multipath *m = pg->m;
>+	unsigned long flags;
>+
>+	/* device or driver problems */
>+	switch (errors) {
>+	case SCSI_DH_OK:
>+		break;
>+	case SCSI_DH_NOSYS:
>+		if (!m->hw_handler_name) {
>+			errors = 0;
>+			break;
>+		}
>+		DMERR("Cannot failover device because scsi_dh_%s was not "
>+		      "loaded.", m->hw_handler_name);
>+		/*
>+		 * Fail path for now, so we do not ping pong
>+		 */
>+		fail_path(pgpath);
>+		break;
>+	case SCSI_DH_DEV_TEMP_BUSY:
>+		/*
>+		 * Probably doing something like FW upgrade on the
>+		 * controller so try the other pg.
>+		 */
>+		bypass_pg(m, pg, 1);
>+		break;
>+	/* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
>+	case SCSI_DH_RETRY:
>+	case SCSI_DH_IMM_RETRY:
>+	case SCSI_DH_RES_TEMP_UNAVAIL:
>+		if (pg_init_limit_reached(m, pgpath))
>+			fail_path(pgpath);
>+		errors = 0;
>+		break;
>+	default:
>+		/*
>+		 * We probably do not want to fail the path for a device
>+		 * error, but this is what the old dm did. In future
>+		 * patches we can do more advanced handling.
>+		 */
>+		fail_path(pgpath);
>+	}
>+
>+	spin_lock_irqsave(&m->lock, flags);
>+	if (errors) {
>+		DMERR("Could not failover device. Error %d.", errors);
>+		m->current_pgpath = NULL;
>+		m->current_pg = NULL;
>+	} else if (!m->pg_init_required) {
>+		m->queue_io = 0;
>+		pg->bypassed = 0;
>+	}
>+
>+	m->pg_init_in_progress = 0;
>+	queue_work(kmultipathd, &m->process_queued_ios);
>+	spin_unlock_irqrestore(&m->lock, flags);
>+}
>+
> /*
>  * end_io handling
>  */
> static int do_end_io(struct multipath *m, struct bio *bio,
> 		     int error, struct mpath_io *mpio)
> {
>-	struct hw_handler *hwh = &m->hw_handler;
>-	unsigned err_flags = MP_FAIL_PATH;	/* Default behavior */
> 	unsigned long flags;
> 
> 	if (!error)
>@@ -1095,19 +1156,8 @@ static int do_end_io(struct multipath *m
> 	}
> 	spin_unlock_irqrestore(&m->lock, flags);
> 
>-	if (hwh->type && hwh->type->error)
>-		err_flags = hwh->type->error(hwh, bio);
>-
>-	if (mpio->pgpath) {
>-		if (err_flags & MP_FAIL_PATH)
>-			fail_path(mpio->pgpath);
>-
>-		if (err_flags & MP_BYPASS_PG)
>-			bypass_pg(m, mpio->pgpath->pg, 1);
>-	}
>-
>-	if (err_flags & MP_ERROR_IO)
>-		return -EIO;
>+	if (mpio->pgpath)
>+		fail_path(mpio->pgpath);
> 
>       requeue:
> 	dm_bio_restore(&mpio->details, bio);
>@@ -1192,7 +1242,6 @@ static int multipath_status(struct dm_ta
> 	int sz = 0;
> 	unsigned long flags;
> 	struct multipath *m = (struct multipath *) ti->private;
>-	struct hw_handler *hwh = &m->hw_handler;
> 	struct priority_group *pg;
> 	struct pgpath *p;
> 	unsigned pg_num;
>@@ -1212,12 +1261,10 @@ static int multipath_status(struct dm_ta
> 			DMEMIT("pg_init_retries %u ", m->pg_init_retries);
> 	}
> 
>-	if (hwh->type && hwh->type->status)
>-		sz += hwh->type->status(hwh, type, result + sz, maxlen - sz);
>-	else if (!hwh->type || type == STATUSTYPE_INFO)
>+	if (!m->hw_handler_name || type == STATUSTYPE_INFO)
> 		DMEMIT("0 ");
> 	else
>-		DMEMIT("1 %s ", hwh->type->name);
>+		DMEMIT("1 %s ", m->hw_handler_name);
> 
> 	DMEMIT("%u ", m->nr_priority_groups);
> 
>Index: linux-2.6.18.ppc64/drivers/md/Kconfig
>===================================================================
>--- linux-2.6.18.ppc64.orig/drivers/md/Kconfig
>+++ linux-2.6.18.ppc64/drivers/md/Kconfig
>@@ -240,6 +240,11 @@ config DM_ZERO
> config DM_MULTIPATH
> 	tristate "Multipath target (EXPERIMENTAL)"
> 	depends on BLK_DEV_DM && EXPERIMENTAL
>+	# nasty syntax but means make DM_MULTIPATH independent
>+	# of SCSI_DH if the latter isn't defined but if
>+	# it is, DM_MULTIPATH must depend on it.  We get a build
>+	# error if SCSI_DH=m and DM_MULTIPATH=y otherwise.
>+	depends on SCSI_DH || !SCSI_DH
> 	---help---
> 	  Allow volume managers to support multipath hardware.
>

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Attachments on bug 438761: 314153 | 314154 | 314155 | 314156 | 314157 | 314158 | 314159 | 314160 | 314161 | 314162 | 314163 | 314339 | 314426 | 314828 | 314829 | 316641