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Commit 1bab0de0 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by James Bottomley
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dm-mpath, scsi_dh: don't let dm detach device handlers 



While allowing dm-mpath to attach device handlers is a functionality we need
for backwards compatibility reason there is no reason to reference count
them and detach them if dm-mpath stops using the device for some reason.

If the device handler works for the given device it can just stay attached,
and we can take the retain_hw_handler codepath.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Acked-by: default avatarHannes Reinecke <hare@Suse.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
parent 36dd5acd

drivers/md/dm-mpath.c

+6 −15
Original line number Diff line number Diff line
@@ -159,12 +159,9 @@ 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);

	}
@@ -580,6 +577,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps 
		q = bdev_get_queue(p->path.dev->bdev);



	if (m->retain_attached_hw_handler) {

retain:

		attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);

		if (attached_handler_name) {

			/*
@@ -599,20 +597,14 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps 
	}



	if (m->hw_handler_name) {

		/*

		 * Increments scsi_dh reference, even when using an

		 * already-attached handler.

		 */

		r = scsi_dh_attach(q, m->hw_handler_name);

		if (r == -EBUSY) {

			/*

			 * Already attached to different hw_handler:

			 * try to reattach with correct one.

			 */

			scsi_dh_detach(q);

			r = scsi_dh_attach(q, m->hw_handler_name);

		}

			char b[BDEVNAME_SIZE];



			printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",

				bdevname(p->path.dev->bdev, b));

			goto retain;

		}

		if (r < 0) {

			ti->error = "error attaching hardware handler";

			dm_put_device(ti, p->path.dev);
@@ -624,7 +616,6 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps 
			if (r < 0) {

				ti->error = "unable to set hardware "

							"handler parameters";

				scsi_dh_detach(q);

				dm_put_device(ti, p->path.dev);

				goto bad;

			}

drivers/scsi/device_handler/scsi_dh.c

+22 −74
Original line number Diff line number Diff line
@@ -100,14 +100,6 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev, 
{

	struct scsi_dh_data *d;



	if (sdev->scsi_dh_data) {

		if (sdev->scsi_dh_data->scsi_dh != scsi_dh)

			return -EBUSY;



		kref_get(&sdev->scsi_dh_data->kref);

		return 0;

	}



	if (!try_module_get(scsi_dh->module))

		return -EINVAL;
@@ -120,7 +112,6 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev, 
	}



	d->scsi_dh = scsi_dh;

	kref_init(&d->kref);

	d->sdev = sdev;



	spin_lock_irq(sdev->request_queue->queue_lock);
@@ -129,12 +120,14 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev, 
	return 0;

}



static void __detach_handler (struct kref *kref)

/*

 * scsi_dh_handler_detach - Detach a device handler from a device

 * @sdev - SCSI device the device handler should be detached from

 */

static void scsi_dh_handler_detach(struct scsi_device *sdev)

{

	struct scsi_dh_data *scsi_dh_data =

		container_of(kref, struct scsi_dh_data, kref);

	struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;

	struct scsi_device_handler *scsi_dh = scsi_dh_data->scsi_dh;

	struct scsi_device *sdev = scsi_dh_data->sdev;



	scsi_dh->detach(sdev);
@@ -146,30 +139,6 @@ static void __detach_handler (struct kref *kref) 
	module_put(scsi_dh->module);

}



/*

 * scsi_dh_handler_detach - Detach a device handler from a device

 * @sdev - SCSI device the device handler should be detached from

 * @scsi_dh - Device handler to be detached

 *

 * Detach from a device handler. If a device handler is specified,

 * only detach if the currently attached handler matches @scsi_dh.

 */

static void scsi_dh_handler_detach(struct scsi_device *sdev,

				   struct scsi_device_handler *scsi_dh)

{

	if (!sdev->scsi_dh_data)

		return;



	if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)

		return;



	if (!scsi_dh)

		scsi_dh = sdev->scsi_dh_data->scsi_dh;



	if (scsi_dh)

		kref_put(&sdev->scsi_dh_data->kref, __detach_handler);

}



/*

 * Functions for sysfs attribute 'dh_state'

 */
@@ -198,7 +167,7 @@ store_dh_state(struct device *dev, struct device_attribute *attr, 
			/*

			 * Detach from a device handler

			 */

			scsi_dh_handler_detach(sdev, scsi_dh);

			scsi_dh_handler_detach(sdev);

			err = 0;

		} else if (!strncmp(buf, "activate", 8)) {

			/*
@@ -290,7 +259,8 @@ static int scsi_dh_notifier(struct notifier_block *nb, 
			err = scsi_dh_handler_attach(sdev, devinfo);

	} else if (action == BUS_NOTIFY_DEL_DEVICE) {

		device_remove_file(dev, &scsi_dh_state_attr);

		scsi_dh_handler_detach(sdev, NULL);

		if (sdev->scsi_dh_data)

			scsi_dh_handler_detach(sdev);

	}

	return err;

}
@@ -335,7 +305,8 @@ static int scsi_dh_notifier_remove(struct device *dev, void *data) 


	sdev = to_scsi_device(dev);



	scsi_dh_handler_detach(sdev, scsi_dh);

	if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh == scsi_dh)

		scsi_dh_handler_detach(sdev);



	put_device(dev);
@@ -517,45 +488,22 @@ int scsi_dh_attach(struct request_queue *q, const char *name) 
		err = -ENODEV;

	spin_unlock_irqrestore(q->queue_lock, flags);



	if (!err) {

		err = scsi_dh_handler_attach(sdev, scsi_dh);

		put_device(&sdev->sdev_gendev);

	}

	if (err)

		return err;

}

EXPORT_SYMBOL_GPL(scsi_dh_attach);



/*

 * scsi_dh_detach - Detach device handler

 * @q - Request queue that is associated with the scsi_device

 *      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) {

		scsi_dh = sdev->scsi_dh_data->scsi_dh;

		scsi_dh_handler_detach(sdev, scsi_dh);

		if (sdev->scsi_dh_data->scsi_dh != scsi_dh)

			err = -EBUSY;

		goto out_put_device;

	}



	err = scsi_dh_handler_attach(sdev, scsi_dh);



out_put_device:

	put_device(&sdev->sdev_gendev);

	return err;

}

EXPORT_SYMBOL_GPL(scsi_dh_detach);

EXPORT_SYMBOL_GPL(scsi_dh_attach);



/*

 * scsi_dh_attached_handler_name - Get attached device handler's name

include/scsi/scsi_device.h

+0 −1
Original line number Diff line number Diff line
@@ -221,7 +221,6 @@ struct scsi_device_handler { 
struct scsi_dh_data {

	struct scsi_device_handler *scsi_dh;

	struct scsi_device *sdev;

	struct kref kref;

};



#define	to_scsi_device(d)	\

include/scsi/scsi_dh.h

+0 −5
Original line number Diff line number Diff line
@@ -59,7 +59,6 @@ enum { 
extern int scsi_dh_activate(struct request_queue *, activate_complete, void *);

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 *);

extern const char *scsi_dh_attached_handler_name(struct request_queue *, gfp_t);

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

#else
@@ -77,10 +76,6 @@ 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;

}

static inline const char *scsi_dh_attached_handler_name(struct request_queue *q,

							gfp_t gfp)

{