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Commit 7ccd0791 authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe
Browse files

loop: Push loop_ctl_mutex down into loop_clr_fd() 



loop_clr_fd() has a weird locking convention that is expects
loop_ctl_mutex held, releases it on success and keeps it on failure.
Untangle the mess by moving locking of loop_ctl_mutex into
loop_clr_fd().

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a2505b79

drivers/block/loop.c

+29 −20
Original line number Diff line number Diff line
@@ -1027,15 +1027,22 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 


static int __loop_clr_fd(struct loop_device *lo)

{

	struct file *filp = lo->lo_backing_file;

	struct file *filp = NULL;

	gfp_t gfp = lo->old_gfp_mask;

	struct block_device *bdev = lo->lo_device;

	int err = 0;



	if (WARN_ON_ONCE(lo->lo_state != Lo_rundown))

		return -ENXIO;

	mutex_lock(&loop_ctl_mutex);

	if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) {

		err = -ENXIO;

		goto out_unlock;

	}



	if (filp == NULL)

		return -EINVAL;

	filp = lo->lo_backing_file;

	if (filp == NULL) {

		err = -EINVAL;

		goto out_unlock;

	}



	/* freeze request queue during the transition */

	blk_mq_freeze_queue(lo->lo_queue);
@@ -1082,6 +1089,7 @@ static int __loop_clr_fd(struct loop_device *lo) 
	if (!part_shift)

		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;

	loop_unprepare_queue(lo);

out_unlock:

	mutex_unlock(&loop_ctl_mutex);

	/*

	 * Need not hold loop_ctl_mutex to fput backing file.
@@ -1089,14 +1097,22 @@ static int __loop_clr_fd(struct loop_device *lo) 
	 * lock dependency possibility warning as fput can take

	 * bd_mutex which is usually taken before loop_ctl_mutex.

	 */

	if (filp)

		fput(filp);

	return 0;

	return err;

}



static int loop_clr_fd(struct loop_device *lo)

{

	if (lo->lo_state != Lo_bound)

	int err;



	err = mutex_lock_killable_nested(&loop_ctl_mutex, 1);

	if (err)

		return err;

	if (lo->lo_state != Lo_bound) {

		mutex_unlock(&loop_ctl_mutex);

		return -ENXIO;

	}

	/*

	 * If we've explicitly asked to tear down the loop device,

	 * and it has an elevated reference count, set it for auto-teardown when
@@ -1113,6 +1129,7 @@ static int loop_clr_fd(struct loop_device *lo) 
		return 0;

	}

	lo->lo_state = Lo_rundown;

	mutex_unlock(&loop_ctl_mutex);



	return __loop_clr_fd(lo);

}
@@ -1447,14 +1464,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
		mutex_unlock(&loop_ctl_mutex);

		break;

	case LOOP_CLR_FD:

		err = mutex_lock_killable_nested(&loop_ctl_mutex, 1);

		if (err)

			return err;

		/* loop_clr_fd would have unlocked loop_ctl_mutex on success */

		err = loop_clr_fd(lo);

		if (err)

			mutex_unlock(&loop_ctl_mutex);

		break;

		return loop_clr_fd(lo);

	case LOOP_SET_STATUS:

		err = -EPERM;

		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
@@ -1690,7 +1700,6 @@ static int lo_open(struct block_device *bdev, fmode_t mode) 
static void lo_release(struct gendisk *disk, fmode_t mode)

{

	struct loop_device *lo;

	int err;



	mutex_lock(&loop_ctl_mutex);

	lo = disk->private_data;
@@ -1701,12 +1710,12 @@ static void lo_release(struct gendisk *disk, fmode_t mode) 
		if (lo->lo_state != Lo_bound)

			goto out_unlock;

		lo->lo_state = Lo_rundown;

		mutex_unlock(&loop_ctl_mutex);

		/*

		 * In autoclear mode, stop the loop thread

		 * and remove configuration after last close.

		 */

		err = __loop_clr_fd(lo);

		if (!err)

		__loop_clr_fd(lo);

		return;

	} else if (lo->lo_state == Lo_bound) {

		/*