Fix tracefs mount options:

The commit 78ff64081949 ("vfs: Convert tracefs to use the new mount API")
broke the gid setting when set by fstab or other mount utility.
It is ignored when it is set. Fix the code so that it recognises the
option again and will honor the settings on mount at boot up.

Update the internal documentation and create a selftest to make sure
it doesn't break again in the future.

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
tracefs/fixes

Head SHA1: 8b55572e51805184353ee7d587c720a51818fb82


Kalesh Singh (3):
      tracing: Fix tracefs mount options
      tracing: Document tracefs gid mount option
      tracing/selftests: Add tracefs mount options test

----
 fs/tracefs/inode.c                                 |  12 ++-
 kernel/trace/trace.c                               |   4 +
 .../ftrace/test.d/00basic/mount_options.tc         | 101 +++++++++++++++++++++
 .../ftrace/test.d/00basic/test_ownership.tc        |  16 +---
 tools/testing/selftests/ftrace/test.d/functions    |  25 +++++
 5 files changed, 142 insertions(+), 16 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc