From 1bab0de0274fbe8c8ac92179e6705584c55ed169 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 27 Aug 2015 14:16:54 +0200 Subject: 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: Christoph Hellwig Acked-by: Mike Snitzer Acked-by: Hannes Reinecke Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 96 ++++++++--------------------------- 1 file changed, 22 insertions(+), 74 deletions(-) (limited to 'drivers/scsi/device_handler') diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index 1efebc9eedfb..869b5bd1ad25 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -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); - } - 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 (err) + return err; 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 -- cgit v1.2.3