On 5/17/2018 8:22 PM, Long Li wrote:
From: Long Li <lon...@microsoft.com>

This patchset implements direct user I/O through RDMA.

In normal code path (even with cache=none), CIFS copies I/O data from
user-space to kernel-space for security reasons.

With this patchset, a new mounting option is introduced to have CIFS pin the
user-space buffer into memory and performs I/O through RDMA. This avoids memory
copy, at the cost of added security risk.

What's the security risk? This type of direct i/o behavior is not
uncommon, and can certainly be made safe, using the appropriate
memory registration and protection domains. Any risk needs to be
stated explicitly, and mitigation provided, or at least described.

Tom.


This patchset is RFC. The work is in progress, do not merge.


Long Li (9):
   Introduce offset for the 1st page in data transfer structures
   Change wdata alloc to support direct pages
   Change rdata alloc to support direct pages
   Change function to support offset when reading pages
   Change RDMA send to regonize page offset in the 1st page
   Change RDMA recv to support offset in the 1st page
   Support page offset in memory regsitrations
   Implement no-copy file I/O interfaces
   Introduce cache=rdma moutning option
  fs/cifs/cifs_fs_sb.h      |   2 +
  fs/cifs/cifsfs.c          |  19 +++
  fs/cifs/cifsfs.h          |   3 +
  fs/cifs/cifsglob.h        |   6 +
  fs/cifs/cifsproto.h       |   4 +-
  fs/cifs/cifssmb.c         |  10 +-
  fs/cifs/connect.c         |  13 +-
  fs/cifs/dir.c             |   5 +
  fs/cifs/file.c            | 351 ++++++++++++++++++++++++++++++++++++++++++----
  fs/cifs/inode.c           |   4 +-
  fs/cifs/smb2ops.c         |   2 +-
  fs/cifs/smb2pdu.c         |  22 ++-
  fs/cifs/smbdirect.c       | 132 ++++++++++-------
  fs/cifs/smbdirect.h       |   2 +-
  fs/read_write.c           |   7 +
  include/linux/ratelimit.h |   2 +-
  16 files changed, 489 insertions(+), 95 deletions(-)

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