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Commit 3148ffbd authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe
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loop: use killable lock in ioctls 



Even after the previous patch to drop lo_ctl_mutex while calling
vfs_getattr(), there are other cases where we can end up sleeping for a
long time while holding lo_ctl_mutex. Let's avoid the uninterruptible
sleep from the ioctls.

Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2d1d4c1e

drivers/block/loop.c

+19 −10
Original line number Diff line number Diff line
@@ -1360,7 +1360,10 @@ 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(&lo->lo_ctl_mutex, 1);

	err = mutex_lock_killable_nested(&lo->lo_ctl_mutex, 1);

	if (err)

		goto out_unlocked;



	switch (cmd) {

	case LOOP_SET_FD:

		err = loop_set_fd(lo, mode, bdev, arg);
@@ -1545,16 +1548,20 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 


	switch(cmd) {

	case LOOP_SET_STATUS:

		mutex_lock(&lo->lo_ctl_mutex);

		err = loop_set_status_compat(

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

		err = mutex_lock_killable(&lo->lo_ctl_mutex);

		if (!err) {

			err = loop_set_status_compat(lo,

						     (const struct compat_loop_info __user *)arg);

			mutex_unlock(&lo->lo_ctl_mutex);

		}

		break;

	case LOOP_GET_STATUS:

		mutex_lock(&lo->lo_ctl_mutex);

		err = loop_get_status_compat(

			lo, (struct compat_loop_info __user *) arg);

		err = mutex_lock_killable(&lo->lo_ctl_mutex);

		if (!err) {

			err = loop_get_status_compat(lo,

						     (struct compat_loop_info __user *)arg);

			/* loop_get_status() unlocks lo_ctl_mutex */

		}

		break;

	case LOOP_SET_CAPACITY:

	case LOOP_CLR_FD:
@@ -1959,7 +1966,9 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd, 
		ret = loop_lookup(&lo, parm);

		if (ret < 0)

			break;

		mutex_lock(&lo->lo_ctl_mutex);

		ret = mutex_lock_killable(&lo->lo_ctl_mutex);

		if (ret)

			break;

		if (lo->lo_state != Lo_unbound) {

			ret = -EBUSY;

			mutex_unlock(&lo->lo_ctl_mutex);