Commit ffdf637a authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman Committed by Xponential31
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Revert "block/loop: Use global lock for ioctl() operation." 



This reverts commit a17189a0e107ee316b3fff61217f5a037357d65e which is
commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream.

Jan Kara has reported seeing problems with this patch applied, as has
Salvatore Bonaccorso, so let's drop it for now.

Reported-by: default avatarSalvatore Bonaccorso <carnil@debian.org>
Reported-by: default avatarJan Kara <jack@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8cdc7ee9

drivers/block/loop.c

+23 −24
Original line number Diff line number Diff line
@@ -81,7 +81,6 @@ 


static DEFINE_IDR(loop_index_idr);

static DEFINE_MUTEX(loop_index_mutex);

static DEFINE_MUTEX(loop_ctl_mutex);



static int max_part;

static int part_shift;
@@ -1013,7 +1012,7 @@ static int loop_clr_fd(struct loop_device *lo) 
	 */

	if (lo->lo_refcnt > 1) {

		lo->lo_flags |= LO_FLAGS_AUTOCLEAR;

		mutex_unlock(&loop_ctl_mutex);

		mutex_unlock(&lo->lo_ctl_mutex);

		return 0;

	}
@@ -1062,12 +1061,12 @@ static int loop_clr_fd(struct loop_device *lo) 
	lo->lo_flags = 0;

	if (!part_shift)

		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;

	mutex_unlock(&loop_ctl_mutex);

	mutex_unlock(&lo->lo_ctl_mutex);

	/*

	 * Need not hold loop_ctl_mutex to fput backing file.

	 * Calling fput holding loop_ctl_mutex triggers a circular

	 * Need not hold lo_ctl_mutex to fput backing file.

	 * Calling fput holding lo_ctl_mutex triggers a circular

	 * lock dependency possibility warning as fput can take

	 * bd_mutex which is usually taken before loop_ctl_mutex.

	 * bd_mutex which is usually taken before lo_ctl_mutex.

	 */

	fput(filp);

	return 0;
@@ -1301,7 +1300,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
	struct loop_device *lo = bdev->bd_disk->private_data;

	int err;



	mutex_lock_nested(&loop_ctl_mutex, 1);

	mutex_lock_nested(&lo->lo_ctl_mutex, 1);

	switch (cmd) {

	case LOOP_SET_FD:

		err = loop_set_fd(lo, mode, bdev, arg);
@@ -1310,7 +1309,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
		err = loop_change_fd(lo, bdev, arg);

		break;

	case LOOP_CLR_FD:

		/* loop_clr_fd would have unlocked loop_ctl_mutex on success */

		/* loop_clr_fd would have unlocked lo_ctl_mutex on success */

		err = loop_clr_fd(lo);

		if (!err)

			goto out_unlocked;
@@ -1341,7 +1340,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
	default:

		err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;

	}

	mutex_unlock(&loop_ctl_mutex);

	mutex_unlock(&lo->lo_ctl_mutex);



out_unlocked:

	return err;
@@ -1474,16 +1473,16 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 


	switch(cmd) {

	case LOOP_SET_STATUS:

		mutex_lock(&loop_ctl_mutex);

		mutex_lock(&lo->lo_ctl_mutex);

		err = loop_set_status_compat(

			lo, (const struct compat_loop_info __user *) arg);

		mutex_unlock(&loop_ctl_mutex);

		mutex_unlock(&lo->lo_ctl_mutex);

		break;

	case LOOP_GET_STATUS:

		mutex_lock(&loop_ctl_mutex);

		mutex_lock(&lo->lo_ctl_mutex);

		err = loop_get_status_compat(

			lo, (struct compat_loop_info __user *) arg);

		mutex_unlock(&loop_ctl_mutex);

		mutex_unlock(&lo->lo_ctl_mutex);

		break;

	case LOOP_SET_CAPACITY:

	case LOOP_CLR_FD:
@@ -1514,9 +1513,9 @@ static int lo_open(struct block_device *bdev, fmode_t mode) 
		goto out;

	}



	mutex_lock(&loop_ctl_mutex);

	mutex_lock(&lo->lo_ctl_mutex);

	lo->lo_refcnt++;

	mutex_unlock(&loop_ctl_mutex);

	mutex_unlock(&lo->lo_ctl_mutex);

out:

	mutex_unlock(&loop_index_mutex);

	return err;
@@ -1526,7 +1525,7 @@ static void __lo_release(struct loop_device *lo) 
{

	int err;



	mutex_lock(&loop_ctl_mutex);

	mutex_lock(&lo->lo_ctl_mutex);



	if (--lo->lo_refcnt)

		goto out;
@@ -1548,7 +1547,7 @@ static void __lo_release(struct loop_device *lo) 
	}



out:

	mutex_unlock(&loop_ctl_mutex);

	mutex_unlock(&lo->lo_ctl_mutex);

}



static void lo_release(struct gendisk *disk, fmode_t mode)
@@ -1594,10 +1593,10 @@ static int unregister_transfer_cb(int id, void *ptr, void *data) 
	struct loop_device *lo = ptr;

	struct loop_func_table *xfer = data;



	mutex_lock(&loop_ctl_mutex);

	mutex_lock(&lo->lo_ctl_mutex);

	if (lo->lo_encryption == xfer)

		loop_release_xfer(lo);

	mutex_unlock(&loop_ctl_mutex);

	mutex_unlock(&lo->lo_ctl_mutex);

	return 0;

}
@@ -1678,7 +1677,7 @@ static int loop_add(struct loop_device **l, int i) 
	if (!part_shift)

		disk->flags |= GENHD_FL_NO_PART_SCAN;

	disk->flags |= GENHD_FL_EXT_DEVT;

	mutex_init(&loop_ctl_mutex);

	mutex_init(&lo->lo_ctl_mutex);

	lo->lo_number		= i;

	lo->lo_thread		= NULL;

	init_waitqueue_head(&lo->lo_event);
@@ -1790,19 +1789,19 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd, 
		ret = loop_lookup(&lo, parm);

		if (ret < 0)

			break;

		mutex_lock(&loop_ctl_mutex);

		mutex_lock(&lo->lo_ctl_mutex);

		if (lo->lo_state != Lo_unbound) {

			ret = -EBUSY;

			mutex_unlock(&loop_ctl_mutex);

			mutex_unlock(&lo->lo_ctl_mutex);

			break;

		}

		if (lo->lo_refcnt > 0) {

			ret = -EBUSY;

			mutex_unlock(&loop_ctl_mutex);

			mutex_unlock(&lo->lo_ctl_mutex);

			break;

		}

		lo->lo_disk->private_data = NULL;

		mutex_unlock(&loop_ctl_mutex);

		mutex_unlock(&lo->lo_ctl_mutex);

		idr_remove(&loop_index_idr, lo->lo_number);

		loop_remove(lo);

		break;

drivers/block/loop.h

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ struct loop_device { 
	struct bio_list		lo_bio_list;

	unsigned int		lo_bio_count;

	int			lo_state;

	struct mutex		lo_ctl_mutex;

	struct task_struct	*lo_thread;

	wait_queue_head_t	lo_event;

	/* wait queue for incoming requests */