staging/lustre/llite: fix O_TMPFILE/O_LOV_DELAY_CREATE conflict

staging/lustre/llite: fix O_TMPFILE/O_LOV_DELAY_CREATE conflict

In kernel 3.11 O_TMPFILE was introduced, but the open flag value
conflicts with the O_LOV_DELAY_CREATE flag 020000000 previously used
by Lustre-aware applications.  O_LOV_DELAY_CREATE allows applications
to defer file layout and object creation from open time (the default)
until it can instead be specified by the application using an ioctl.

Instead of trying to find a non-conflicting O_LOV_DELAY_CREATE flag
or define a Lustre-specific flag that isn't of use to most/any other
filesystems, use (O_NOCTTY|FASYNC) as the new value.  These flags
are not meaningful for newly-created regular files and should be
OK since O_LOV_DELAY_CREATE is only meaningful for new files.

I looked into using O_ACCMODE/FMODE_WRITE_IOCTL, which allows calling
ioctl() on the minimally-opened fd and is close to what is needed,
but that doesn't allow specifying the actual read or write mode for
the file, and fcntl(F_SETFL) doesn't allow O_RDONLY/O_WRONLY/O_RDWR
to be set after the file is opened.

Lustre-change: http://review.whamcloud.com/8312
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4209
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>