Fix problems relating to execution of files on GFS2
This patch fixes a couple of problems which affected the execution of files on GFS2.
The first is that there was a corner case where inodes were not always uptodate at
the point at which permissions checks were being carried out, this was resulting in
refusal of execute permission, but only on the first lookup, subsequent requests
worked correctly. The second was a problem relating to incorrect updating of file sizes
which was introduced with the write_begin/end code for GFS2 a little while back.
Signed-off-by: Steven Whitehouse <firstname.lastname@example.org>