Commit 362529d9 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: split __blkdev_get 



Split __blkdev_get into one helper for the whole device, and one for
opening partitions.  This removes the (bounded) recursion when opening
a partition.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20210525061301.2242282-2-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent da7ba729

fs/block_dev.c

+57 −61
Original line number Diff line number Diff line
@@ -1290,79 +1290,69 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate) 
 */

EXPORT_SYMBOL_GPL(bdev_disk_changed);



/*

 * bd_mutex locking:

 *

 *  mutex_lock(part->bd_mutex)

 *    mutex_lock_nested(whole->bd_mutex, 1)

 */

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

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

{

	struct gendisk *disk = bdev->bd_disk;

	int ret = 0;



	if (!(disk->flags & GENHD_FL_UP))

		return -ENXIO;



	if (!bdev->bd_openers) {

		if (!bdev_is_partition(bdev)) {

			ret = 0;

			if (disk->fops->open)

	if (disk->fops->open) {

		ret = disk->fops->open(bdev, mode);

		if (ret) {

			/* avoid ghost partitions on a removed medium */

			if (ret == -ENOMEDIUM &&

			     test_bit(GD_NEED_PART_SCAN, &disk->state))

				bdev_disk_changed(bdev, true);

			return ret;

		}

	}



			if (!ret)

	if (!bdev->bd_openers) {

		set_init_blocksize(bdev);

		if (bdev->bd_bdi == &noop_backing_dev_info)

			bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);

	}

	if (test_bit(GD_NEED_PART_SCAN, &disk->state))

		bdev_disk_changed(bdev, false);

	bdev->bd_openers++;

	return 0;;

}



			/*

			 * If the device is invalidated, rescan partition

			 * if open succeeded or failed with -ENOMEDIUM.

			 * The latter is necessary to prevent ghost

			 * partitions on a removed medium.

			 */

			if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&

			    (!ret || ret == -ENOMEDIUM))

				bdev_disk_changed(bdev, ret == -ENOMEDIUM);

static int blkdev_get_part(struct block_device *part, fmode_t mode)

{

	struct gendisk *disk = part->bd_disk;

	struct block_device *whole;

	int ret;



			if (ret)

				return ret;

		} else {

			struct block_device *whole = bdgrab(disk->part0);

	if (part->bd_openers)

		goto done;



	whole = bdgrab(disk->part0);

	mutex_lock_nested(&whole->bd_mutex, 1);

			ret = __blkdev_get(whole, mode);

	ret = blkdev_get_whole(whole, mode);

	if (ret) {

		mutex_unlock(&whole->bd_mutex);

				bdput(whole);

				return ret;

		goto out_put_whole;

	}

	whole->bd_part_count++;

	mutex_unlock(&whole->bd_mutex);



			if (!bdev_nr_sectors(bdev)) {

	ret = -ENXIO;

	if (!bdev_nr_sectors(part))

		goto out_blkdev_put;



	set_init_blocksize(part);

	if (part->bd_bdi == &noop_backing_dev_info)

		part->bd_bdi = bdi_get(disk->queue->backing_dev_info);

done:

	part->bd_openers++;

	return 0;



out_blkdev_put:

	__blkdev_put(whole, mode, 1);

out_put_whole:

	bdput(whole);

				return -ENXIO;

			}

			set_init_blocksize(bdev);

		}



		if (bdev->bd_bdi == &noop_backing_dev_info)

			bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);

	} else {

		if (!bdev_is_partition(bdev)) {

			if (bdev->bd_disk->fops->open)

				ret = bdev->bd_disk->fops->open(bdev, mode);

			/* the same as first opener case, read comment there */

			if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&

			    (!ret || ret == -ENOMEDIUM))

				bdev_disk_changed(bdev, ret == -ENOMEDIUM);

			if (ret)

	return ret;

}

	}

	bdev->bd_openers++;

	return 0;

}



struct block_device *blkdev_get_no_open(dev_t dev)

{
@@ -1448,7 +1438,13 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) 
	disk_block_events(disk);



	mutex_lock(&bdev->bd_mutex);

	ret =__blkdev_get(bdev, mode);

	ret = -ENXIO;

	if (!(disk->flags & GENHD_FL_UP))

		goto abort_claiming;

	if (bdev_is_partition(bdev))

		ret = blkdev_get_part(bdev, mode);

	else

		ret = blkdev_get_whole(bdev, mode);

	if (ret)

		goto abort_claiming;

	if (mode & FMODE_EXCL) {