ocfs2: Fix a bug in direct IO read.

ocfs2 will become read-only if we try to read the bytes which pass
the end of i_size. This can be easily reproduced by following steps:
1. mkfs a ocfs2 volume with bs=4k cs=4k and nosparse.
2. create a small file(say less than 100 bytes) and we will create the file
   which is allocated 1 cluster.
3. read 8196 bytes from the kernel using O_DIRECT which exceeds the limit.
4. The ocfs2 volume becomes read-only and dmesg shows:
OCFS2: ERROR (device sda13): ocfs2_direct_IO_get_blocks:
Inode 66010 has a hole at block 1
File system is now read-only due to the potential of on-disk corruption.
Please run fsck.ocfs2 once the file system is unmounted.

So suppress the ERROR message.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/aops.c

@@ -594,7 +594,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 		goto bail;
 	}
 
-	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno) {
+	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno && create) {
 		ocfs2_error(inode->i_sb,
 			    "Inode %llu has a hole at block %llu\n",
 			    (unsigned long long)OCFS2_I(inode)->ip_blkno,