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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: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Omar Sandoval 2018-03-26 21:39:12 -07:00 committed by Jens Axboe
parent 2d1d4c1e59
commit 3148ffbdb9
1 changed files with 19 additions and 10 deletions
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29
drivers/block/loop.c
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@ -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);
mutex_unlock(&lo->lo_ctl_mutex);
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);
/* loop_get_status() unlocks lo_ctl_mutex */
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);