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Commit ae11b1b3 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by James Bottomley
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[SCSI] scsi_dh: attach to hardware handler from dm-mpath 



multipath keeps a separate device table which may be
more current than the built-in one.
So we should make sure to always call ->attach whenever
a multipath map with hardware handler is instantiated.
And we should call ->detach on removal, too.

[sekharan: update as per comments from agk]
Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarChandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 057ea7c9

drivers/md/dm-mpath.c

+13 −0
Original line number Diff line number Diff line
@@ -147,9 +147,12 @@ static struct priority_group *alloc_priority_group(void) 
static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)

{

	struct pgpath *pgpath, *tmp;

	struct multipath *m = 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);

	}
@@ -548,6 +551,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 
{

	int r;

	struct pgpath *p;

	struct multipath *m = ti->private;



	/* we need at least a path arg */

	if (as->argc < 1) {
@@ -566,6 +570,15 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 
		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);

drivers/scsi/device_handler/scsi_dh.c

+64 −0
Original line number Diff line number Diff line
@@ -369,6 +369,70 @@ int scsi_dh_handler_exist(const char *name) 
}

EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);



/*

 * scsi_dh_handler_attach - Attach device handler

 * @sdev - sdev the handler should be attached to

 * @name - name of the handler to attach

 */

int scsi_dh_attach(struct request_queue *q, const char *name)

{

	unsigned long flags;

	struct scsi_device *sdev;

	struct scsi_device_handler *scsi_dh;

	int err = 0;



	scsi_dh = get_device_handler(name);

	if (!scsi_dh)

		return -EINVAL;



	spin_lock_irqsave(q->queue_lock, flags);

	sdev = q->queuedata;

	if (!sdev || !get_device(&sdev->sdev_gendev))

		err = -ENODEV;

	spin_unlock_irqrestore(q->queue_lock, flags);



	if (!err) {

		err = scsi_dh_handler_attach(sdev, scsi_dh);



		put_device(&sdev->sdev_gendev);

	}

	return err;

}

EXPORT_SYMBOL_GPL(scsi_dh_attach);



/*

 * scsi_dh_handler_detach - Detach device handler

 * @sdev - sdev the handler should be detached from

 *

 * This function will detach the device handler only

 * if the sdev is not part of the internal list, ie

 * if it has been attached manually.

 */

void scsi_dh_detach(struct request_queue *q)

{

	unsigned long flags;

	struct scsi_device *sdev;

	struct scsi_device_handler *scsi_dh = NULL;



	spin_lock_irqsave(q->queue_lock, flags);

	sdev = q->queuedata;

	if (!sdev || !get_device(&sdev->sdev_gendev))

		sdev = NULL;

	spin_unlock_irqrestore(q->queue_lock, flags);



	if (!sdev)

		return;



	if (sdev->scsi_dh_data) {

		/* if sdev is not on internal list, detach */

		scsi_dh = sdev->scsi_dh_data->scsi_dh;

		if (!device_handler_match(scsi_dh, sdev))

			scsi_dh_handler_detach(sdev, scsi_dh);

	}

	put_device(&sdev->sdev_gendev);

}

EXPORT_SYMBOL_GPL(scsi_dh_detach);



static struct notifier_block scsi_dh_nb = {

	.notifier_call = scsi_dh_notifier

};

include/scsi/scsi_dh.h

+10 −0
Original line number Diff line number Diff line
@@ -58,6 +58,8 @@ enum { 
#if defined(CONFIG_SCSI_DH) || defined(CONFIG_SCSI_DH_MODULE)

extern int scsi_dh_activate(struct request_queue *);

extern int scsi_dh_handler_exist(const char *);

extern int scsi_dh_attach(struct request_queue *, const char *);

extern void scsi_dh_detach(struct request_queue *);

#else

static inline int scsi_dh_activate(struct request_queue *req)

{
@@ -67,4 +69,12 @@ static inline int scsi_dh_handler_exist(const char *name) 
{

	return 0;

}

static inline int scsi_dh_attach(struct request_queue *req, const char *name)

{

	return SCSI_DH_NOSYS;

}

static inline void scsi_dh_detach(struct request_queue *q)

{

	return;

}

#endif