[RFC PATCH v3 0/5] UBIFS: add ACL support

[Sheng Yong]

Hi, folks,
These patches add ACL support for UBIFS.

UBIFS ACL is based on xattr, which simplifies the implementation without
considering budget and sync.

New kernel/mount options, CONFIG_UBIFS_FS_POSIX_ACL and `-o acl', are
introduced to enable or disable UBIFS ACL.

`acl.c' provides format conversion between in-memory ACL and on-flash ACL.
Each time a new inode is created, the correspondng ACL xattr is built
(except for the inode of an xattr dent). 

Testcases (adjusted to mount an UBI volume) in LTP [1] are passed.

Any comment is appreciated. More test is appreciated.

V3:
* Use POSIX generic ACL structures and functions to do the conversions
  between in-memory and on-flash ACL. Thanks Dongsheng Yang for pointing
  this out.
* Remove ACL if size is 0 when setting ACL.
* Clear cached ACL when ACL xattr is removed.

V2:
* Do not set ACL-xattr-handler, and call generic ACL handler in xattr
  functions.
http://lists.infradead.org/pipermail/linux-mtd/2015-September/061672.html

V1:
http://lists.infradead.org/pipermail/linux-mtd/2015-March/058452.html

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/fs/acl/tacl_xattr.sh

thanks,
Sheng

Sheng Yong (5):
  UBIFS: ACL: introduce init/set/get functions for ACL
  UBIFS: ACL: set ACL interfaces in inode_operations
  UBIFS: ACL: handle ACL through xattr
  UBIFS: ACL: introduce ACL mount options
  UBIFS: ACL: add ACL config option

 fs/ubifs/Kconfig  |  11 +++
 fs/ubifs/Makefile |   1 +
 fs/ubifs/acl.c    | 141 +++++++++++++++++++++++++++++++
 fs/ubifs/dir.c    |  20 +++++
 fs/ubifs/file.c   |  14 ++++
 fs/ubifs/super.c  |  15 ++++
 fs/ubifs/ubifs.h  |  14 ++++
 fs/ubifs/xattr.c  | 243 ++++++++++++++++++++++++++++++++++--------------------
 8 files changed, 369 insertions(+), 90 deletions(-)
 create mode 100644 fs/ubifs/acl.c

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1.9.1