Re: [PATCH v2 2/5] dax: fallback from pmd to pte on error

Jeff Moyer
2016-04-15T14:55:47Z

Vishal Verma <vishal.l.verma@intel.com> writes:

> From: Dan Williams <dan.j.williams@intel.com>
>
> In preparation for consulting a badblocks list in pmem_direct_access(),
> teach dax_pmd_fault() to fallback rather than fail immediately upon
> encountering an error. The thought being that reducing the span of the
> dax request may avoid the error region.
>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>

> ---
> fs/dax.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 90322eb..ec6417b 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -945,8 +945,8 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> long length = dax_map_atomic(bdev, &dax);
>
> if (length < 0) {
> - result = VM_FAULT_SIGBUS;
> - goto out;
> + dax_pmd_dbg(&bh, address, "dax-error fallback");
> + goto fallback;
> }
> if (length < PMD_SIZE) {
> dax_pmd_dbg(&bh, address, "dax-length too small");