From: Huaisheng Ye <yehs1@xxxxxxxxxx> Changes since v1 [1]: * Involve the previous patches for pfn can be NULL. * Reword the patch descriptions according to Christian's comment. * According to Ross's suggestion, replace local pointer dummy_addr with NULL within md/dm-writecache for direct_access. [1]: https://lkml.org/lkml/2018/7/24/199 Some functions within fs/dax, dax/super and md/dm-writecache don't need to get local pointer kaddr or variable pfn from direct_access. Assigning NULL to kaddr or pfn to ->direct_access() is more straightforward and simple than offering a useless local pointer or variable. So all ->direct_access() need to check the validity of pointer kaddr and pfn for NULL assignment. If either of them is equal to NULL, that is to say callers may have no need for kaddr or pfn, so this series of patch are prepared for allowing them to pass in NULL instead of having to pass in a local pointer or variable that they then just throw away. Huaisheng Ye (6): libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access() s390, dcssblk: kaddr and pfn can be NULL to ->direct_access() tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access() dax/super: Do not request a pointer kaddr when not required md/dm-writecache: Don't request pointer dummy_addr when not required filesystem-dax: Do not request kaddr and pfn when not required drivers/dax/super.c | 3 +-- drivers/md/dm-writecache.c | 3 +-- drivers/nvdimm/pmem.c | 7 +++++-- drivers/s390/block/dcssblk.c | 8 +++++--- fs/dax.c | 13 ++++--------- tools/testing/nvdimm/pmem-dax.c | 12 ++++++++---- 6 files changed, 24 insertions(+), 22 deletions(-) -- 1.8.3.1
