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Commit 6a027eff authored by Tejun Heo's avatar Tejun Heo
Browse files

block: reorganize claim/release implementation 



With claim/release rolled into blkdev_get/put(), there's no reason to
keep bd_abort/finish_claim(), __bd_claim() and bd_release() as
separate functions.  It only makes the code difficult to follow.
Collapse them into blkdev_get/put().  This will ease future changes
around claim/release.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent e525fd89

fs/block_dev.c

+48 −79
Original line number Diff line number Diff line
@@ -772,79 +772,6 @@ static struct block_device *bd_start_claiming(struct block_device *bdev, 
	}

}



/* releases bdev_lock */

static void __bd_abort_claiming(struct block_device *whole, void *holder)

{

	BUG_ON(whole->bd_claiming != holder);

	whole->bd_claiming = NULL;

	wake_up_bit(&whole->bd_claiming, 0);



	spin_unlock(&bdev_lock);

	bdput(whole);

}



/**

 * bd_abort_claiming - abort claiming a block device

 * @whole: whole block device returned by bd_start_claiming()

 * @holder: holder trying to claim @bdev

 *

 * Abort a claiming block started by bd_start_claiming().  Note that

 * @whole is not the block device to be claimed but the whole device

 * returned by bd_start_claiming().

 *

 * CONTEXT:

 * Grabs and releases bdev_lock.

 */

static void bd_abort_claiming(struct block_device *whole, void *holder)

{

	spin_lock(&bdev_lock);

	__bd_abort_claiming(whole, holder);		/* releases bdev_lock */

}



/* increment holders when we have a legitimate claim. requires bdev_lock */

static void __bd_claim(struct block_device *bdev, struct block_device *whole,

					void *holder)

{

	/* note that for a whole device bd_holders

	 * will be incremented twice, and bd_holder will

	 * be set to bd_may_claim before being set to holder

	 */

	whole->bd_holders++;

	whole->bd_holder = bd_may_claim;

	bdev->bd_holders++;

	bdev->bd_holder = holder;

}



/**

 * bd_finish_claiming - finish claiming a block device

 * @bdev: block device of interest (passed to bd_start_claiming())

 * @whole: whole block device returned by bd_start_claiming()

 * @holder: holder trying to claim @bdev

 *

 * Finish a claiming block started by bd_start_claiming().

 *

 * CONTEXT:

 * Grabs and releases bdev_lock.

 */

static void bd_finish_claiming(struct block_device *bdev,

				struct block_device *whole, void *holder)

{

	spin_lock(&bdev_lock);

	BUG_ON(!bd_may_claim(bdev, whole, holder));

	__bd_claim(bdev, whole, holder);

	__bd_abort_claiming(whole, holder); /* not actually an abort */

}



static void bd_release(struct block_device *bdev)

{

	spin_lock(&bdev_lock);

	if (!--bdev->bd_contains->bd_holders)

		bdev->bd_contains->bd_holder = NULL;

	if (!--bdev->bd_holders)

		bdev->bd_holder = NULL;

	spin_unlock(&bdev_lock);

}



#ifdef CONFIG_SYSFS

static int add_symlink(struct kobject *from, struct kobject *to)

{
@@ -1223,10 +1150,30 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) 
	res = __blkdev_get(bdev, mode, 0);



	if (whole) {

		if (res == 0)

			bd_finish_claiming(bdev, whole, holder);

		else

			bd_abort_claiming(whole, holder);

		/* finish claiming */

		spin_lock(&bdev_lock);



		if (res == 0) {

			BUG_ON(!bd_may_claim(bdev, whole, holder));

			/*

			 * Note that for a whole device bd_holders

			 * will be incremented twice, and bd_holder

			 * will be set to bd_may_claim before being

			 * set to holder

			 */

			whole->bd_holders++;

			whole->bd_holder = bd_may_claim;

			bdev->bd_holders++;

			bdev->bd_holder = holder;

		}



		/* tell others that we're done */

		BUG_ON(whole->bd_claiming != holder);

		whole->bd_claiming = NULL;

		wake_up_bit(&whole->bd_claiming, 0);



		spin_unlock(&bdev_lock);

		bdput(whole);

	}



	return res;
@@ -1272,6 +1219,7 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) 
		bdev->bd_part_count--;



	if (!--bdev->bd_openers) {

		WARN_ON_ONCE(bdev->bd_holders);

		sync_blockdev(bdev);

		kill_bdev(bdev);

	}
@@ -1303,10 +1251,31 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) 
int blkdev_put(struct block_device *bdev, fmode_t mode)

{

	if (mode & FMODE_EXCL) {

		bool bdev_free;



		/*

		 * Release a claim on the device.  The holder fields

		 * are protected with bdev_lock.  bd_mutex is to

		 * synchronize disk_holder unlinking.

		 */

		mutex_lock(&bdev->bd_mutex);

		bd_release(bdev);

		if (!bdev->bd_holders)

		spin_lock(&bdev_lock);



		WARN_ON_ONCE(--bdev->bd_holders < 0);

		WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);



		/* bd_contains might point to self, check in a separate step */

		if ((bdev_free = !bdev->bd_holders))

			bdev->bd_holder = NULL;

		if (!bdev->bd_contains->bd_holders)

			bdev->bd_contains->bd_holder = NULL;



		spin_unlock(&bdev_lock);



		/* if this was the last claim, holder link should go too */

		if (bdev_free)

			bd_unlink_disk_holder(bdev);



		mutex_unlock(&bdev->bd_mutex);

	}

	return __blkdev_put(bdev, mode, 0);