Commit 9a8887a9 authored by zhangyi (F)'s avatar zhangyi (F) Committed by Xie XiuQi
Browse files

block: add info when opening a write opend block device exclusively 



euler inclusion
category: feature
bugzilla: 14367
CVE: NA
---------------------------

Just like open an exclusive opened block device for write, open a block
device exclusively which has been opened for write by some other
processes may also lead to potential data corruption. This patch record
the write openers and give a hint if that happens.

Signed-off-by: default avatarzhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: default avatarMiao Xie <miaoxie@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parent 14eae9d6

fs/block_dev.c

+18 −2
Original line number Diff line number Diff line
@@ -1563,6 +1563,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) 
	bdev->bd_openers++;

	if (for_part)

		bdev->bd_part_count++;

	if (mode & FMODE_WRITE)

		bdev->bd_write_openers++;

	mutex_unlock(&bdev->bd_mutex);

	disk_unblock_events(disk);

	/* only one opener holds refs to the module and disk */
@@ -1611,6 +1613,7 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) 
{

	struct block_device *whole = NULL;

	int res;

	char name[BDEVNAME_SIZE];



	WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
@@ -1630,6 +1633,19 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) 
	if (whole) {

		struct gendisk *disk = whole->bd_disk;



		/*

		 * Open an write opened block device exclusively, the

		 * writing process may probability corrupt the device,

		 * such as a mounted file system, give a hint here.

		 */

		if (!res && (bdev->bd_write_openers >

		    ((mode & FMODE_WRITE) ? 1 : 0)) && !bdev->bd_holders) {

			pr_info_ratelimited("VFS: Open an write opened "

				"block device exclusively %s [%d %s].\n",

				bdevname(bdev, name), current->pid,

				current->comm);

		}



		/* finish claiming */

		if (!res) {

			BUG_ON(!bd_may_claim(bdev, whole, holder));
@@ -1669,8 +1685,6 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) 
		bdput(whole);

	} else {

		if (!res && (mode & FMODE_WRITE) && bdev->bd_holders) {

			char name[BDEVNAME_SIZE];



			/*

			 * Open an exclusive opened device for write may

			 * probability corrupt the device, such as a
@@ -1805,6 +1819,8 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) 
	struct block_device *victim = NULL;



	mutex_lock_nested(&bdev->bd_mutex, for_part);

	if (mode & FMODE_WRITE)

		bdev->bd_write_openers--;

	if (for_part)

		bdev->bd_part_count--;

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -455,6 +455,7 @@ struct request_queue; 
struct block_device {

	dev_t			bd_dev;  /* not a kdev_t - it's a search key */

	int			bd_openers;

	int			bd_write_openers;

	struct inode *		bd_inode;	/* will die */

	struct super_block *	bd_super;

	struct mutex		bd_mutex;	/* open/close mutex */