[PATCH v2 0/2] Use exclusive lock for file_remove_privs

[Bernd Schubert <bschubert@ddn.com>]

While adding shared direct IO write locks to fuse Miklos noticed
that file_remove_privs() needs an exclusive lock. I then
noticed that btrfs actually has the same issue as I had in my patch,
it was calling into that function with a shared lock.
This series adds a new exported function file_needs_remove_privs(),
which used by the follow up btrfs patch and will be used by the
DIO code path in fuse as well. If that function returns any mask
the shared lock needs to be dropped and replaced by the exclusive
variant.

Note: Compilation tested only.

v2:
Already check for IS_NOSEC in btrfs_direct_write before the first
lock is taken.
Slight modification to make the code easier to read (boolean pointer
is passed to btrfs_write_check, instead of flags).

Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Dharmendra Singh <dsingh@ddn.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org


Bernd Schubert (2):
  fs: Add and export file_needs_remove_privs
  btrfs: file_remove_privs needs an exclusive lock

 fs/btrfs/file.c    | 37 +++++++++++++++++++++++++++++--------
 fs/inode.c         |  8 ++++++++
 include/linux/fs.h |  1 +
 3 files changed, 38 insertions(+), 8 deletions(-)

-- 
2.39.2