Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1a3cbbc5 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: factor out bd_may_claim() 



Factor out bd_may_claim() from bd_claim(), add comments and apply a
couple of cosmetic edits.  This is to prepare for further updates to
claim path.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent afc24d49

fs/block_dev.c

+47 −18
Original line number Diff line number Diff line
@@ -661,41 +661,70 @@ void bd_forget(struct inode *inode) 
		iput(bdev->bd_inode);

}



int bd_claim(struct block_device *bdev, void *holder)

/**

 * bd_may_claim - test whether a block device can be claimed

 * @bdev: block device of interest

 * @whole: whole block device containing @bdev, may equal @bdev

 * @holder: holder trying to claim @bdev

 *

 * Test whther @bdev can be claimed by @holder.

 *

 * CONTEXT:

 * spin_lock(&bdev_lock).

 *

 * RETURNS:

 * %true if @bdev can be claimed, %false otherwise.

 */

static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,

			 void *holder)

{

	int res;

	spin_lock(&bdev_lock);



	/* first decide result */

	if (bdev->bd_holder == holder)

		res = 0;	 /* already a holder */

		return true;	 /* already a holder */

	else if (bdev->bd_holder != NULL)

		res = -EBUSY; 	 /* held by someone else */

		return false; 	 /* held by someone else */

	else if (bdev->bd_contains == bdev)

		res = 0;  	 /* is a whole device which isn't held */

		return true;  	 /* is a whole device which isn't held */



	else if (bdev->bd_contains->bd_holder == bd_claim)

		res = 0; 	 /* is a partition of a device that is being partitioned */

	else if (bdev->bd_contains->bd_holder != NULL)

		res = -EBUSY;	 /* is a partition of a held device */

	else if (whole->bd_holder == bd_claim)

		return true; 	 /* is a partition of a device that is being partitioned */

	else if (whole->bd_holder != NULL)

		return false;	 /* is a partition of a held device */

	else

		res = 0;	 /* is a partition of an un-held device */

		return true;	 /* is a partition of an un-held device */

}



	/* now impose change */

	if (res==0) {

/**

 * bd_claim - claim a block device

 * @bdev: block device to claim

 * @holder: holder trying to claim @bdev

 *

 * Try to claim @bdev.

 *

 * RETURNS:

 * 0 if successful, -EBUSY if @bdev is already claimed.

 */

int bd_claim(struct block_device *bdev, void *holder)

{

	struct block_device *whole = bdev->bd_contains;

	int res = -EBUSY;



	spin_lock(&bdev_lock);



	if (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_claim before being set to holder

		 */

		bdev->bd_contains->bd_holders ++;

		bdev->bd_contains->bd_holder = bd_claim;

		whole->bd_holders++;

		whole->bd_holder = bd_claim;

		bdev->bd_holders++;

		bdev->bd_holder = holder;

		res = 0;

	}



	spin_unlock(&bdev_lock);

	return res;

}



EXPORT_SYMBOL(bd_claim);



void bd_release(struct block_device *bdev)