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Commit 89f97496 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block: fix __blkdev_get() for removable devices 



Commit 0762b8bd moved disk_get_part()
in front of recursive get on the whole disk, which caused removable
devices to try disk_get_part() before rescanning after a new media is
inserted, which might fail legit open attempts or give the old
partition.

This patch fixes the problem by moving disk_get_part() after
__blkdev_get() on the whole disk.

This problem was spotted by Borislav Petkov.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Tested-by: default avatarBorislav Petkov <petkovbb@gmail.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 561920a0

fs/block_dev.c

+11 −12
Original line number Diff line number Diff line
@@ -986,7 +986,6 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); 
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)

{

	struct gendisk *disk;

	struct hd_struct *part = NULL;

	int ret;

	int partno;

	int perm = 0;
@@ -1004,24 +1003,25 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
		return ret;

	}



	ret = -ENXIO;



	lock_kernel();



	ret = -ENXIO;

	disk = get_gendisk(bdev->bd_dev, &partno);

	if (!disk)

		goto out_unlock_kernel;

	part = disk_get_part(disk, partno);

	if (!part)

		goto out_unlock_kernel;



	mutex_lock_nested(&bdev->bd_mutex, for_part);

	if (!bdev->bd_openers) {

		bdev->bd_disk = disk;

		bdev->bd_part = part;

		bdev->bd_contains = bdev;

		if (!partno) {

			struct backing_dev_info *bdi;



			ret = -ENXIO;

			bdev->bd_part = disk_get_part(disk, partno);

			if (!bdev->bd_part)

				goto out_clear;



			if (disk->fops->open) {

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

				if (ret)
@@ -1049,18 +1049,17 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
			bdev->bd_contains = whole;

			bdev->bd_inode->i_data.backing_dev_info =

			   whole->bd_inode->i_data.backing_dev_info;

			bdev->bd_part = disk_get_part(disk, partno);

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

			    !part || !part->nr_sects) {

			    !bdev->bd_part || !bdev->bd_part->nr_sects) {

				ret = -ENXIO;

				goto out_clear;

			}

			bd_set_size(bdev, (loff_t)part->nr_sects << 9);

			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);

		}

	} else {

		disk_put_part(part);

		put_disk(disk);

		module_put(disk->fops->owner);

		part = NULL;

		disk = NULL;

		if (bdev->bd_contains == bdev) {

			if (bdev->bd_disk->fops->open) {
@@ -1080,6 +1079,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
	return 0;



 out_clear:

	disk_put_part(bdev->bd_part);

	bdev->bd_disk = NULL;

	bdev->bd_part = NULL;

	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
@@ -1091,7 +1091,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
 out_unlock_kernel:

	unlock_kernel();



	disk_put_part(part);

	if (disk)

		module_put(disk->fops->owner);

	put_disk(disk);