On Tue, Oct 10, 2017 at 07:49:30AM -0700, Dan Williams wrote:
> @@ -1009,6 +1019,22 @@ xfs_file_llseek(
> }
>
> /*
> + * MAP_DIRECT faults can only be serviced while the FL_LAYOUT lease is
> + * valid. See map_direct_invalidate.
> + */
> +static int
> +xfs_can_fault_direct(
> + struct vm_area_struct *vma)
> +{
> + if (!xfs_vma_is_direct(vma))
> + return 0;
> +
> + if (!test_map_direct_valid(vma->vm_private_data))
> + return VM_FAULT_SIGBUS;
> + return 0;
> +}
Better, but I'm going to be an annoying pedant here: a "can
<something>" check should return a boolean true/false.
Also, it's a bit jarring to see that a non-direct VMA that /can't/
do direct faults returns the same thing as a direct-vma that /can/
do direct faults, so a couple of extra comments for people who will
quickly forget how this code works (i.e. me) will be helpful. Say
something like this:
/*
* MAP_DIRECT faults can only be serviced while the FL_LAYOUT lease is
* valid. See map_direct_invalidate.
*/
static bool
xfs_vma_has_direct_lease(
struct vm_area_struct *vma)
{
/* Non MAP_DIRECT vmas do not require layout leases */
if (!xfs_vma_is_direct(vma))
return true;
if (!test_map_direct_valid(vma->vm_private_data))
return false;
/* We have a valid lease */
return true;
}
.....
if (!xfs_vma_has_direct_lease(vma)) {
ret = VM_FAULT_SIGBUS;
goto out_unlock;
}
....
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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