NFS: Remove redundant waits for O_DIRECT in fsync() and write_begin()

We're now waiting immediately after taking the locks, so waiting
in fsync() and write_begin() is either redundant or potentially
subject to livelock (if not holding the lock).
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/file.c

@@ -276,7 +276,6 @@ nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 
 	trace_nfs_fsync_enter(inode);
 
-	inode_dio_wait(inode);
 	do {
 		ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
 		if (ret != 0)
@@ -361,11 +360,6 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
 		file, mapping->host->i_ino, len, (long long) pos);
 
 start:
-	/*
-	 * Wait for O_DIRECT to complete
-	 */
-	inode_dio_wait(mapping->host);
-
 	page = grab_cache_page_write_begin(mapping, index, flags);
 	if (!page)
 		return -ENOMEM;