Commit 0e345826 authored by Jan Beulich's avatar Jan Beulich Committed by Jens Axboe
Browse files

blkfront: fixes for 'xm block-detach ... --force' 



Prevent prematurely freeing 'struct blkfront_info' instances (when the
xenbus data structures are gone, but the Linux ones are still needed).

Prevent adding a disk with the same (major, minor) [and hence the same
name and sysfs entries, which leads to oopses] when the previous
instance wasn't fully de-allocated yet.

This still doesn't address all issues resulting from forced detach:
I/O submitted after the detach still blocks forever, likely preventing
subsequent un-mounting from completing. It's not clear to me (not
knowing much about the block layer) how this can be avoided.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 203fd61f

drivers/block/xen-blkfront.c

+81 −7
Original line number Diff line number Diff line
@@ -105,6 +105,10 @@ struct blkfront_info 


static DEFINE_SPINLOCK(blkif_io_lock);



static unsigned int nr_minors;

static unsigned long *minors;

static DEFINE_SPINLOCK(minor_lock);



#define MAXIMUM_OUTSTANDING_BLOCK_REQS \

	(BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)

#define GRANT_INVALID_REF	0
@@ -139,6 +143,55 @@ static void add_id_to_freelist(struct blkfront_info *info, 
	info->shadow_free = id;

}



static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)

{

	unsigned int end = minor + nr;

	int rc;



	if (end > nr_minors) {

		unsigned long *bitmap, *old;



		bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),

				 GFP_KERNEL);

		if (bitmap == NULL)

			return -ENOMEM;



		spin_lock(&minor_lock);

		if (end > nr_minors) {

			old = minors;

			memcpy(bitmap, minors,

			       BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));

			minors = bitmap;

			nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;

		} else

			old = bitmap;

		spin_unlock(&minor_lock);

		kfree(old);

	}



	spin_lock(&minor_lock);

	if (find_next_bit(minors, end, minor) >= end) {

		for (; minor < end; ++minor)

			__set_bit(minor, minors);

		rc = 0;

	} else

		rc = -EBUSY;

	spin_unlock(&minor_lock);



	return rc;

}



static void xlbd_release_minors(unsigned int minor, unsigned int nr)

{

	unsigned int end = minor + nr;



	BUG_ON(end > nr_minors);

	spin_lock(&minor_lock);

	for (; minor < end; ++minor)

		__clear_bit(minor, minors);

	spin_unlock(&minor_lock);

}



static void blkif_restart_queue_callback(void *arg)

{

	struct blkfront_info *info = (struct blkfront_info *)arg;
@@ -417,9 +470,14 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 
	if ((minor % nr_parts) == 0)

		nr_minors = nr_parts;



	err = xlbd_reserve_minors(minor, nr_minors);

	if (err)

		goto out;

	err = -ENODEV;



	gd = alloc_disk(nr_minors);

	if (gd == NULL)

		goto out;

		goto release;



	offset = minor / nr_parts;
@@ -450,7 +508,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 


	if (xlvbd_init_blk_queue(gd, sector_size)) {

		del_gendisk(gd);

		goto out;

		goto release;

	}



	info->rq = gd->queue;
@@ -470,6 +528,8 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 


	return 0;



 release:

	xlbd_release_minors(minor, nr_minors);

 out:

	return err;

}
@@ -924,6 +984,7 @@ static void blkfront_connect(struct blkfront_info *info) 
static void blkfront_closing(struct xenbus_device *dev)

{

	struct blkfront_info *info = dev_get_drvdata(&dev->dev);

	unsigned int minor, nr_minors;

	unsigned long flags;



	dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
@@ -946,7 +1007,10 @@ static void blkfront_closing(struct xenbus_device *dev) 
	blk_cleanup_queue(info->rq);

	info->rq = NULL;



	minor = info->gd->first_minor;

	nr_minors = info->gd->minors;

	del_gendisk(info->gd);

	xlbd_release_minors(minor, nr_minors);



 out:

	xenbus_frontend_closed(dev);
@@ -1004,7 +1068,10 @@ static int blkfront_remove(struct xenbus_device *dev) 


	blkif_free(info, 0);



	if(info->users == 0)

		kfree(info);

	else

		info->is_ready = -1;



	return 0;

}
@@ -1013,18 +1080,22 @@ static int blkfront_is_ready(struct xenbus_device *dev) 
{

	struct blkfront_info *info = dev_get_drvdata(&dev->dev);



	return info->is_ready;

	return info->is_ready > 0;

}



static int blkif_open(struct block_device *bdev, fmode_t mode)

{

	struct blkfront_info *info = bdev->bd_disk->private_data;

	int ret = 0;



	lock_kernel();

	if (info->is_ready < 0)

		ret = -ENODEV;

	else

		info->users++;

	unlock_kernel();



	return 0;

	return ret;

}



static int blkif_release(struct gendisk *disk, fmode_t mode)
@@ -1039,7 +1110,10 @@ static int blkif_release(struct gendisk *disk, fmode_t mode) 
		struct xenbus_device *dev = info->xbdev;

		enum xenbus_state state = xenbus_read_driver_state(dev->otherend);



		if (state == XenbusStateClosing && info->is_ready)

		if(info->is_ready < 0) {

			blkfront_closing(dev);

			kfree(info);

		} else if (state == XenbusStateClosing && info->is_ready)

			blkfront_closing(dev);

	}

	unlock_kernel();

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