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dm-mpath, scsi_dh: don't let dm detach device handlers

Browse source 
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: Christoph Hellwig <[email protected]>
Acked-by: Mike Snitzer <[email protected]>
Acked-by: Hannes Reinecke <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
This commit is contained in:
Christoph Hellwig 2015-08-27 14:16:54 +02:00 • committed by James Bottomley
commit 1bab0de027
4 changed files with 28 additions and 95 deletions
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98
drivers/scsi/device_handler/scsi_dh.c
View file

@ -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);
@ -517,46 +488,23 @@ 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;
if (sdev->scsi_dh_data) {
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_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);
}
put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL_GPL(scsi_dh_detach);
/*
* scsi_dh_attached_handler_name - Get attached device handler's name
* @q - Request queue that is associated with the scsi_device