If filesystem was aborted we will return success
due to (sb->s_flags & MS_RDONLY) which is incorrect and
results in data loss.
In order to handle fs abort correctly we have to check
fs state once we discover that it is in MS_RDONLY state

Test case: http://patchwork.ozlabs.org/patch/244297/
Changes from V1:
 - fix spelling
 - fix smp_rmb()/debug order
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>