[PATCH v2 0/4] Assigning NULL to gfn of dax_direct_access if useless

[Huaisheng Ye <yehs2007@zoho.com>]

From: Huaisheng Ye <yehs1@lenovo.com>

Changes since v1 [1]:
* Collect Jan's reviewed-by.
* According to Dan's suggestion, update the unit test infrastructure
  tools/testing/nvdimm/pmem-dax.c for checking the validity of gfn.

[1]: https://lkml.org/lkml/2018/7/4/81

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Some functions within fs/dax don't need to get gfn from direct_access.
Assigning NULL to gfn of dax_direct_access is more intuitive and simple
than offering a useless local variable.

So all direct_access need to check the validity of pointer pfn for NULL
assignment. If pfn equals to NULL, it doesn't need to calculate its value.

---

Huaisheng Ye (4):
  nvdimm/pmem: check the validity of the pointer pfn
  nvdimm/pmem-dax: check the validity of the pointer pfn
  s390/block/dcssblk: check the validity of the pointer pfn
  fs/dax: Assign NULL to gfn of dax_direct_access if useless

 drivers/nvdimm/pmem.c           | 3 ++-
 drivers/s390/block/dcssblk.c    | 3 ++-
 fs/dax.c                        | 9 +++------
 tools/testing/nvdimm/pmem-dax.c | 6 ++++--
 4 files changed, 11 insertions(+), 10 deletions(-)

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