Changes since v1 :
* Fix the detection of device-dax file instances in vma_is_fsdax().
* Fix compile breakage in the FS_DAX=n and DEV_DAX=y case. (0day robot)
The vfio interface, like RDMA, wants to setup long term (indefinite)
pins of the pages backing an address range so that a guest or userspace
driver can perform DMA to the with physical address. Given that this
pinning may lead to filesystem operations deadlocking in the
filesystem-dax case, the pinning request needs to be rejected.
The longer term fix for vfio, RDMA, and any other long term pin user, is
to provide a 'pin with lease' mechanism. Similar to the leases that are
hold for pNFS RDMA layouts, this userspace lease gives the kernel a way
to notify userspace that the block layout of the file is changing and
the kernel is revoking access to pinned pages.
Dan Williams (5):
dax: fix vma_is_fsdax() helper
dax: fix dax_mapping() definition in the FS_DAX=n + DEV_DAX=y case
dax: fix S_DAX definition
dax: short circuit vma_is_fsdax() in the CONFIG_FS_DAX=n case
vfio: disable filesystem-dax page pinning
drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++---
include/linux/dax.h | 9 ++++++---
include/linux/fs.h | 6 ++++--
3 files changed, 25 insertions(+), 8 deletions(-)