ocfs2: implement ocfs2_direct_IO_write

ocfs2: implement ocfs2_direct_IO_write

Implement ocfs2_direct_IO_write.  Add the inode to orphan dir first, and
then delete it once append O_DIRECT finished.

This is to make sure block allocation and inode size are consistent.

[[email protected]: fix it for "block: Add discard flag to blkdev_issue_zeroout() function"]
Signed-off-by: Joseph Qi <[email protected]>
Cc: Weiwei Wang <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Xuejiufei <[email protected]>
Cc: alex chen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>